Atmosphere

26 pages, 2375 KiB

Open AccessArticle

Contributions of Atmospheric Transport and Rain–Vapor Exchange to Near-Surface Water Vapor in the Zhanjiang Mangrove Reserve, Southern China: An Isotopic Perspective

by Xiang Lai, Jonathon S. Wright, Wenyu Huang, Jie Liang, Guanghui Lin and Shanxian Zhu

Atmosphere 2018, 9(9), 365; https://doi.org/10.3390/atmos9090365 - 19 Sep 2018

Cited by 6 | Viewed by 4745

Abstract

Coastal mangroves are increasingly recognized as valuable natural resources and important sites of water and carbon exchange. In this study, we examine atmospheric water cycling in the boundary layer above a coastal mangrove forest in southern China. We collected site observations of isotopic [...] Read more.

Coastal mangroves are increasingly recognized as valuable natural resources and important sites of water and carbon exchange. In this study, we examine atmospheric water cycling in the boundary layer above a coastal mangrove forest in southern China. We collected site observations of isotopic ratios in water vapor and precipitation along with core meteorological variables during July 2017. Our evaluation of these data highlights the influences of large-scale atmospheric transport and rain–vapor exchange in the boundary layer water budget. Rain–vapor exchange takes different forms for different types of rainfall events. The evolution of isotopic ratios in water vapor suggests that substantial rain recycling occurs during the passage of large-scale organized convective systems, but that this process is much weaker during rainfall associated with less organized events of local origin. We further examine the influences of large-scale transport during the observation period using a Lagrangian trajectory-based moisture source analysis. More than half (63%) of the boundary layer moisture during the study period traced back to the South China Sea, consistent with prevailing southerly to southwesterly flow. Other important moisture sources included mainland Southeast Asia and the Indian Ocean, local land areas (e.g., Hainan Island and the Leizhou Peninsula), and the Pacific Ocean. Together, these five regions contributed more than 90% of the water vapor. The most pronounced changes in isotopic content due to large-scale transport during the study period were related to the passage of Tropical Storm Talas. The outer rain bands of this tropical cyclone passed over the measurement site on 15–17 July, causing a sharp reduction in the heavy isotopic content of boundary layer water vapor and a substantial increase in deuterium excess. These changes are consistent with extensive isotopic distillation and rain–vapor exchange in downdrafts associated with the intense convective systems produced by this storm. Full article

(This article belongs to the Section Biosphere/Hydrosphere/Land–Atmosphere Interactions)

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19 pages, 2885 KiB

Open AccessArticle

Single Scattering Albedo’s Spectral Dependence Effect on UV Irradiance

by Ioannis-Panagiotis Raptis, Stelios Kazadzis, Kostas Eleftheratos, Vassilis Amiridis and Ilias Fountoulakis

Atmosphere 2018, 9(9), 364; https://doi.org/10.3390/atmos9090364 - 19 Sep 2018

Cited by 16 | Viewed by 6094

Abstract

The absorbing and scattering nature of aerosols affects the total radiative forcing and is quantified by single scattering albedo (SSA), which is defined as the absorption to total extinction ratio. There are limited measurements of SSA in the ultraviolet (UV) irradiance spectrum, hence, [...] Read more.

The absorbing and scattering nature of aerosols affects the total radiative forcing and is quantified by single scattering albedo (SSA), which is defined as the absorption to total extinction ratio. There are limited measurements of SSA in the ultraviolet (UV) irradiance spectrum, hence, the influence of SSA on incoming UV irradiance has not been explored in great depth. In the present study, UV irradiance was calculated and compared using different SSA datasets retrieved at Athens, Greece during 2009–2014; including SSA time series from Ultraviolet Multi-Filter Radiometer (UVMFR) at 332 and 368 nm, SSA from AERONET at 440 nm, from OMI satellite at 342.5 nm and AeroCom climatological database at 300 nm. Irradiances were estimated using a radiative transfer model (RTM). Comparisons of these results revealed that relative differences of UVA and UVB could be as high as 20%, whilst average relative differences varied from 2% to 8.7% for the entire experimental period. Both UVA and UVB drop by a rate of ~12% for 0.05 aerosol absorption optical depth in comparison to ones estimated with the use of SSA at visible range. Brewer irradiance measurements at 324 nm were used to validate modeled monochromatic irradiances and a better agreement was found when UVMFR SSAs were used with an average difference of 0.86%. However, when using visible or climatological input, relative differences were estimated +4.91% and +4.15% accordingly. Full article

(This article belongs to the Section Aerosols)

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25 pages, 4581 KiB

Open AccessArticle

Impact of Air Mass Conditions and Aerosol Properties on Ice Nucleating Particle Concentrations at the High Altitude Research Station Jungfraujoch

by Larissa Lacher, Martin Steinbacher, Nicolas Bukowiecki, Erik Herrmann, Assaf Zipori and Zamin A. Kanji

Atmosphere 2018, 9(9), 363; https://doi.org/10.3390/atmos9090363 - 19 Sep 2018

Cited by 21 | Viewed by 6112

Abstract

Ice nucleation is the source of primary ice crystals in mixed-phase clouds. Only a small fraction of aerosols called ice nucleating particles (INPs) catalyze ice formation, with their nature and origin remaining unclear. In this study, we investigate potential predictor parameters of meteorological [...] Read more.

Ice nucleation is the source of primary ice crystals in mixed-phase clouds. Only a small fraction of aerosols called ice nucleating particles (INPs) catalyze ice formation, with their nature and origin remaining unclear. In this study, we investigate potential predictor parameters of meteorological conditions and aerosol properties for INP concentrations at mixed-phase cloud condition at 242 K. Measurements were conducted at the High Altitude Research Station Jungfraujoch (Switzerland, 3580 m a.s.l.), which is located predominantly in the free troposphere (FT) but can occasionally receive injections from the boundary layer (BLI). Measurements are taken during a long-term study of eight field campaigns, allowing for the first time an interannual (2014–2017) and seasonal (spring, summer, and winter) distinction of high-time-resolution INP measurements. We investigate ranked correlation coefficients between INP concentrations and meteorological parameters and aerosol properties. While a commonly used parameterization lacks in predicting the observed INP concentrations, the best INP predictor is the total available surface area of the aerosol particles, with no obvious seasonal trend in the relationship. Nevertheless, the predicting capability is less pronounced in the FT, which might be caused by ageing effects. Furthermore, there is some evidence of anthropogenic influence on INP concentrations during BLI. Our study contributes to an improved understanding of ice nucleation in the free troposphere, however, it also underlines that a knowledge gap of ice nucleation in such an environment exists. Full article

(This article belongs to the Special Issue Ice Nucleation in the Atmosphere)

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20 pages, 16175 KiB

Open AccessArticle

Extreme Rainfall Forecast with the WRF-ARW Model in the Central Andes of Peru

by Aldo S. Moya-Álvarez, José Gálvez, Andrea Holguín, René Estevan, Shailendra Kumar, Elver Villalobos, Daniel Martínez-Castro and Yamina Silva

Atmosphere 2018, 9(9), 362; https://doi.org/10.3390/atmos9090362 - 18 Sep 2018

Cited by 36 | Viewed by 8222

Abstract

The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated in this study, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. [...] Read more.

The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated in this study, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. The evaluation analyzes the synoptic conditions averaged over 40 extreme event cases, and considers model simulations organized in 4 nested domains. We first establish that atypical events in the region are those with more than 27 mm of rainfall per day when averaging over all the stations. More than 50% of the selected cases occurred during January, February, and April, with the most extreme occurring during February. The average synoptic conditions show negative geopotential anomalies and positive humidity anomalies in 700 and 500 hPa. At 200 hPa, the subtropical upper ridge or “Bolivian high” was present, with its northern divergent flank over the Mantaro basin. Simulation results show that the Weather Research and Forecasting (WRF) model underestimates rainfall totals in approximately 50–60% of cases, mainly in the south of the basin and in the extreme west along the mountain range. The analysis of two case studies shows that the underestimation by the model is probably due to three reasons: inability to generate convection in the upstream Amazon during early morning hours, apparently related to processes of larger scales; limitations on describing mesoscale processes that lead to vertical movements capable of producing extreme rainfall; and limitations on the microphysics scheme to generate heavy rainfall. Full article

(This article belongs to the Section Meteorology)

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18 pages, 4196 KiB

Open AccessReview

Current Challenges in Orographic Flow Dynamics: Turbulent Exchange Due to Low-Level Gravity-Wave Processes

by Simon B. Vosper, Andrew N. Ross, Ian A. Renfrew, Peter Sheridan, Andrew D. Elvidge and Vanda Grubišić

Atmosphere 2018, 9(9), 361; https://doi.org/10.3390/atmos9090361 - 18 Sep 2018

Cited by 25 | Viewed by 6116

Abstract

This paper examines current understanding of the influence of orographic flow dynamics on the turbulent transport of momentum and scalar quantities above complex terrain. It highlights three key low-level orographic flow phenomena governed by gravity-wave dynamics: Foehn flow, atmospheric rotors and gravity-wave modulation [...] Read more.

This paper examines current understanding of the influence of orographic flow dynamics on the turbulent transport of momentum and scalar quantities above complex terrain. It highlights three key low-level orographic flow phenomena governed by gravity-wave dynamics: Foehn flow, atmospheric rotors and gravity-wave modulation of the stable boundary layer. Recent observations and numerical simulations are used to illustrate how these flows can cause significant departures from the turbulent fluxes, which occur over flat terrain. Orographically forced fluxes of heat, moisture and chemical constituents are currently unaccounted for in numerical models. Moreover, whilst turbulent orographic drag parameterisation schemes are available (in some models), these do not represent the large gravity-wave scales associated with foehn dynamics; nor do they account for the spatio-temporal heterogeneity and non-local turbulence advection observed in wave-rotor dynamics or the gravity waves, which modulate turbulence in the boundary layer. The implications for numerical models, which do not resolve these flows, and for the parametrisation schemes, which should account for the unresolved fluxes, are discussed. An overarching need is identified for improved understanding of the heterogeneity in sub-grid-scale processes, such as turbulent fluxes, associated with orographic flows, and to develop new physically-based approaches for parameterizing these processes. Full article

(This article belongs to the Special Issue Atmospheric Processes over Complex Terrain)

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30 pages, 4544 KiB

Open AccessArticle

Influence of Disdrometer Type on Weather Radar Algorithms from Measured DSD: Application to Italian Climatology

by Elisa Adirosi, Nicoletta Roberto, Mario Montopoli, Eugenio Gorgucci and Luca Baldini

Atmosphere 2018, 9(9), 360; https://doi.org/10.3390/atmos9090360 - 18 Sep 2018

Cited by 35 | Viewed by 4769

Abstract

Relations for retrieving precipitation and attenuation information from radar measurements play a key role in radar meteorology. The uncertainty in such relations highly affects the precipitation and attenuation estimates. Weather radar algorithms are often derived by applying regression methods to precipitation measurements and [...] Read more.

Relations for retrieving precipitation and attenuation information from radar measurements play a key role in radar meteorology. The uncertainty in such relations highly affects the precipitation and attenuation estimates. Weather radar algorithms are often derived by applying regression methods to precipitation measurements and radar observables simulated from datasets of drop size distributions (DSD) using microphysical and electromagnetic assumptions. DSD datasets can be derived from theoretical considerations or obtained from experimental measurements collected throughout the years by disdrometers. Although the relations obtained from experimental disdrometer datasets can be generally considered more representative of a specific climatology, the measuring errors, which depend on the specific type of disdrometer used, introduce an element of uncertainty to the final retrieval algorithms. Eventually, data quality checks and filtering procedures applied to disdrometer measurements play an important role. In this study, we pursue two main goals: (i) evaluate two different techniques for establishing weather radar algorithms from measured DSD, and (ii) investigate to what extent dual-polarization radar algorithms derived from experimental DSD datasets are influenced by the different error structures introduced by the various disdrometer types (namely 2D video disdrometer, first and second generation of OTT Parsivel disdrometer, and Thies Clima disdrometer) used to collect the data. Furthermore, weather radar algorithms optimized for Italian climatology are presented and discussed. Full article

(This article belongs to the Special Issue Precipitation: Measurement and Modeling)

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16 pages, 4364 KiB

Open AccessArticle

Characteristics of Atmospheric Boundary Layer Structure during PM_2.5 and Ozone Pollution Events in Wuhan, China

by Yassin Mbululo, Jun Qin, Jun Hong and Zhengxuan Yuan

Atmosphere 2018, 9(9), 359; https://doi.org/10.3390/atmos9090359 - 18 Sep 2018

Cited by 10 | Viewed by 4434

Abstract

In this study, we investigated six air pollutants from 21 monitoring stations scattered throughout Wuhan city by analyzing meteorological variables in the atmospheric boundary layer (ABL) and air mass backward trajectories from HYSPLIT during the pollution events. Together with this, ground meteorological variables [...] Read more.

In this study, we investigated six air pollutants from 21 monitoring stations scattered throughout Wuhan city by analyzing meteorological variables in the atmospheric boundary layer (ABL) and air mass backward trajectories from HYSPLIT during the pollution events. Together with this, ground meteorological variables were also used throughout the investigation period: 1 December 2015 to 30 November 2016. Analysis results during this period show that the city was polluted in winter by PM_2.5 (particulate matter with aerodynamics of less than 2.5 microns) and in summer by ozone (O₃). The most polluted day during the investigation period was 25 December 2015 with an air quality index (AQI) of 330 which indicates ‘severe pollution’, while the cleanest day was 26 August 2016 with an AQI of 27 indicating ‘excellent’ air quality. The average concentration of PM_2.5 (O₃) on the most polluted day was 265.04 (135.82) µg/m³ and 9.10 (86.40) µg/m³ on the cleanest day. Moreover, the percentage of days which exceeded the daily average limit of NO₂, PM₁₀, PM_2.5, and O₃ for the whole year was 2.46%, 14.48%, 23.50%, and 39.07%, respectively, while SO₂ and CO were found to be below the set daily limit. The analysis of ABL during PM_2.5 pollution events showed the existence of a strong inversion layer, low relative humidity, and calm wind. These observed conditions are not favorable for horizontal and vertical dispersion of air pollutants and therefore result in pollutant accumulation. Likewise, ozone pollution events were accompanied by extended sunshine hours, high temperature, a calm wind, a strongly suspended inversion layer, and zero recorded rainfall. These general characteristics are favorable for photochemical production of ozone and accumulation of pollutants. Apart from the conditions of ABL, the results from backward trajectories suggest trans-boundary movement of air masses to be one of the important factors which determines the air quality of Wuhan. Full article

(This article belongs to the Special Issue Air Quality in China: Past, Present and Future)

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16 pages, 1909 KiB

Open AccessArticle

Environmentally-Related Cherry Root Cambial Plasticity

by Mirjana Ljubojević, Ivana Maksimović, Branislava Lalić, Ljiljana Dekić, Tijana Narandžić, Nenad Magazin, Jovana Dulić, Maja Miodragović, Goran Barać and Vladislav Ognjanov

Atmosphere 2018, 9(9), 358; https://doi.org/10.3390/atmos9090358 - 17 Sep 2018

Cited by 6 | Viewed by 4038

Abstract

The general aim of this research was to determine whether the cherry root cambium possesses similar water-stress adaptation abilities as the scion. Specifically, this study aimed to determine whether there is a shift in root xylem structure due to precipitation fluctuations and temperature [...] Read more.

The general aim of this research was to determine whether the cherry root cambium possesses similar water-stress adaptation abilities as the scion. Specifically, this study aimed to determine whether there is a shift in root xylem structure due to precipitation fluctuations and temperature increase during the growing season in two cherry species. Oblačinska sour cherry and European ground cherry roots with secondary structure were anatomically surveyed in detail, and correlated with meteorological conditions occurring during the vegetation when the roots were formed. Under environmental signals, both investigated species altered their radial root growth imprinting stops and starts in a cambial activity that resulted in the occurrence of intra-annual false growth rings. Changing environmental conditions triggered the shifts of large and small vessels throughout the false growth rings, but their size seemed to be mainly genetically controlled. Taking into consideration all the above, genotypes with moderate vessel lumen area—lesser or around 1200 μm² in the inner zone, as well as no greater than 1500 μm² in the outer zone—are presumed to be both size-controlling and stable upon the drought events. Thus, further field trials will be focused on the SV2 European ground cherry genotype, and OV13, OV32, and OV34 Oblačinska sour cherry genotypes. Full article

(This article belongs to the Special Issue Weather and Climate Change Challenges in Agricultural and Forest Meteorology)

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13 pages, 2674 KiB

Open AccessArticle

Development, Characterization, and Validation of a Cold Stage-Based Ice Nucleation Array (PKU-INA)

by Jie Chen, Xiangyu Pei, Hong Wang, Jingchuan Chen, Yishu Zhu, Mingjin Tang and Zhijun Wu

Atmosphere 2018, 9(9), 357; https://doi.org/10.3390/atmos9090357 - 17 Sep 2018

Cited by 19 | Viewed by 4500

Abstract

A drop-freeze array (PeKing University Ice Nucleation Array, PKU-INA) was developed based on the cold-stage method to investigate heterogeneous ice nucleation properties of atmospheric particles in the immersion freezing mode from −30 to 0 °C. The instrumental details as well as characterization and [...] Read more.

A drop-freeze array (PeKing University Ice Nucleation Array, PKU-INA) was developed based on the cold-stage method to investigate heterogeneous ice nucleation properties of atmospheric particles in the immersion freezing mode from −30 to 0 °C. The instrumental details as well as characterization and performance evaluation are described in this paper. A careful temperature calibration protocol was developed in our work. The uncertainties in the reported temperatures were found to be less than 0.4 °C at various cooling rates after calibration. We also measured the ice nucleation activities of droplets containing different mass concentrations of illite NX, and the results obtained in our work show good agreement with those reported previously using other instruments with similar principles. Overall, we show that our newly developed PKU-INA is a robust and reliable instrument for investigation of heterogeneous ice nucleation in the immersion freezing mode. Full article

(This article belongs to the Special Issue Aerosol-Cloud Interactions)

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16 pages, 2787 KiB

Open AccessArticle

Comparison of Closed Chamber and Eddy Covariance Methods to Improve the Understanding of Methane Fluxes from Rice Paddy Fields in Japan

by Nongpat Chaichana, Sonoko Dorothea Bellingrath-Kimura, Shujiro Komiya, Yoshiharu Fujii, Kosuke Noborio, Ottfried Dietrich and Tiwa Pakoktom

Atmosphere 2018, 9(9), 356; https://doi.org/10.3390/atmos9090356 - 15 Sep 2018

Cited by 23 | Viewed by 6116

Abstract

Greenhouse gas flux monitoring in ecosystems is mostly conducted by closed chamber and eddy covariance techniques. To determine the relevance of the two methods in rice paddy fields at different growing stages, closed chamber (CC) and eddy covariance (EC) methods were used to [...] Read more.

Greenhouse gas flux monitoring in ecosystems is mostly conducted by closed chamber and eddy covariance techniques. To determine the relevance of the two methods in rice paddy fields at different growing stages, closed chamber (CC) and eddy covariance (EC) methods were used to measure the methane (CH₄) fluxes in a flooded rice paddy field. Intensive monitoring using the CC method was conducted at 30, 60 and 90 days after transplanting (DAT) and after harvest (AHV). An EC tower was installed at the centre of the experimental site to provide continuous measurements during the rice cropping season. The CC method resulted in CH₄ flux averages that were 58%, 81%, 94% and 57% higher than those measured by the EC method at 30, 60 and 90 DAT and after harvest (AHV), respectively. A footprint analysis showed that the area covered by the EC method in this study included non-homogeneous land use types. The different strengths and weaknesses of the CC and EC methods can complement each other, and the use of both methods together leads to a better understanding of CH₄ emissions from paddy fields. Full article

(This article belongs to the Special Issue C and N Cycling and Greenhouse Gases Emission in Agroecosystem)

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19 pages, 3625 KiB

Open AccessEditor’s ChoiceArticle

Spatio-Temporal Characteristics of Tropospheric Ozone and Its Precursors in Guangxi, South China

by Yapeng Wang, Chao Yu, Jinhua Tao, Zifeng Wang, Yidan Si, Liangxiao Cheng, Hongmei Wang, Songyan Zhu and Liangfu Chen

Atmosphere 2018, 9(9), 355; https://doi.org/10.3390/atmos9090355 - 14 Sep 2018

Cited by 10 | Viewed by 5138

Abstract

The temporal and spatial distributions of tropospheric ozone and its precursors (NO₂, CO, HCHO) are analyzed over Guangxi (GX) in South China. We used tropospheric column ozone (TCO) from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) onboard the [...] Read more.

The temporal and spatial distributions of tropospheric ozone and its precursors (NO₂, CO, HCHO) are analyzed over Guangxi (GX) in South China. We used tropospheric column ozone (TCO) from the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) onboard the Aura satellite (OMI/MLS), NO₂ and HCHO from OMI and CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument in the period 2005–2016. The TCO shows strong seasonality, with the highest value in spring and the lowest value observed in the monsoon season. The seasonal variation of HCHO is similar to that of TCO, while NO₂ and CO show slightly different patterns with higher values in spring and winter compared to lower values in autumn and summer. The surface ozone, NO₂ and CO observed by national air quality monitoring network sites are also compared with satellite-observed TCO, NO₂ and CO, showing good agreement for NO₂ and CO but a different seasonal pattern for ozone. Unlike TCO, surface ozone has the highest value in autumn and the lowest value in winter. To reveal the difference, the vertical profiles of ozone and CO from the measurement of ozone and water vapor by airbus in-service aircraft (MOZAIC) observations over South China are also examined. The seasonal averaged vertical profiles of ozone and CO show obvious enhancements at 2–6 km altitudes in spring. Furthermore, we investigate the dependence of TCO and surface ozone on meteorology and transport in detail along with the ECMWF reanalysis data, Tropical Rainfall Measuring Mission (TRMM) 3BV42 dataset, OMI ultraviolet index (UV index) dataset, MODIS Fire Radiative Power (FRP) and back trajectory. Our results show that the wind pattern at 800 hPa plays a significant role in determining the seasonality of TCO over GX, especially for the highest value in spring. Trajectory analysis, combined with MODIS FRP suggests that the air masses that passed through the biomass burning (BB) region of Southeast Asia (SEA) induced the enhancement of TCO and CO in the upper-middle troposphere in spring. However, the seasonal cycle of surface ozone is associated with wind patterns at 950 hPa, and the contribution of the photochemical effect is offset by the strong summer monsoon, which results in the maximum surface ozone concentration in post-monsoon September. The variations in the meteorological conditions at different levels and the influence of transport from SEA can account for the vertical distribution of ozone and CO. We conclude that the seasonal distribution of TCO results from the combined impact of meteorology and long-term transport. Full article

(This article belongs to the Special Issue Air Quality in China: Past, Present and Future)

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10 pages, 2631 KiB

Open AccessArticle

Future-Year Ozone Isopleths for South Coast, San Joaquin Valley, and Maryland

by Susan Collet, Toru Kidokoro, Prakash Karamchandani and Tejas Shah

Atmosphere 2018, 9(9), 354; https://doi.org/10.3390/atmos9090354 - 14 Sep 2018

Cited by 6 | Viewed by 5346

Abstract

Many areas of the United States are working toward achieving the 2015 ozone National Ambient Air Quality Standard (NAAQS) attainment level. The objective of this study was to develop future-year (2030) volatile organic compounds and nitrogen oxides (VOC-NO_x) isopleth diagrams of [...] Read more.

Many areas of the United States are working toward achieving the 2015 ozone National Ambient Air Quality Standard (NAAQS) attainment level. The objective of this study was to develop future-year (2030) volatile organic compounds and nitrogen oxides (VOC-NO_x) isopleth diagrams of the 4th highest maximum daily 8-h average ozone design value concentrations at monitors of interest in the South Coast Air Basin (SoCAB) and San Joaquin Valley (SJV) in California, and in Maryland. The simulation results showed there would be attainment of the 2015 ozone NAAQS in 2030 without further controls at the selected monitors: 27% in SoCAB, 57% in SJV, and 100% in Maryland. The SoCAB ozone isopleths developed in this study were compared with those reported in the South Coast Air Quality Management District 2016 Air Quality Management Plan. There are several differences between the two modeling studies, the results are qualitatively similar for most of the monitors in the relative amounts of additional emission reductions needed to achieve the ozone NAAQS. The results of this study provide insight into designing potential control strategies for ozone attainment in future years for areas currently in non-attainment. Additional photochemical modeling using these strategies can then provide confirmation of the effectiveness of the controls. Full article

(This article belongs to the Special Issue Air Quality Prediction)

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20 pages, 6891 KiB

Open AccessEditor’s ChoiceArticle

Quantifying the Effect of Different Urban Planning Strategies on Heat Stress for Current and Future Climates in the Agglomeration of The Hague (The Netherlands)

by Sytse Koopmans, Reinder Ronda, Gert-Jan Steeneveld, Albert A.M. Holtslag and Albert M.G. Klein Tank

Atmosphere 2018, 9(9), 353; https://doi.org/10.3390/atmos9090353 - 13 Sep 2018

Cited by 19 | Viewed by 6706

Abstract

In the Netherlands, there will be an urgent need for additional housing by the year 2040, which mainly has to be realized within the existing built environment rather than in the spatial extension of cities. In this data-driven study, we investigated the effects [...] Read more.

In the Netherlands, there will be an urgent need for additional housing by the year 2040, which mainly has to be realized within the existing built environment rather than in the spatial extension of cities. In this data-driven study, we investigated the effects of different urban planning strategies on heat stress for the current climate and future climate scenarios (year 2050) for the urban agglomeration of The Hague. Heat stress is here expressed as the number of days exceeding minimum temperatures of 20 °C in a year. Thereto, we applied a diagnostic equation to determine the daily maximum urban heat island based on routine meteorological observations and straightforward urban morphological properties including the sky-view factor and the vegetation fraction. Moreover, we utilized the Royal Netherlands Meteorological Institute’s (KNMI) climate scenarios to transform present-day meteorological hourly time series into the future time series. The urban planning strategies differ in replacing low- and mid-rise buildings with high-rise buildings (which reduces the sky-view factor), and constructing buildings on green areas (which reduces the vegetation fraction). We found that, in most cases, the vegetation fraction is a more critical parameter than the sky-view factor to minimize the extra heat stress incurred when densifying the neighbourhood. This means that an urban planning strategy consisting of high-rise buildings and preserved green areas is often the best solution. Still, climate change will have a larger impact on heat stress for the year 2050 than the imposed urban densification. Full article

(This article belongs to the Special Issue Impacts of Climate Change on Human Health)

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14 pages, 3968 KiB

Open AccessEditor’s ChoiceArticle

Effects of El-Niño, Indian Ocean Dipole, and Madden-Julian Oscillation on Surface Air Temperature and Rainfall Anomalies over Southeast Asia in 2015

by M. Amirul Islam, Andy Chan, Matthew J. Ashfold, Chel Gee Ooi and Majid Azari

Atmosphere 2018, 9(9), 352; https://doi.org/10.3390/atmos9090352 - 12 Sep 2018

Cited by 27 | Viewed by 7380

Abstract

The Maritime Continent (MC) is positioned between the Asian and Australian summer monsoons zone. The complex topography and shallow seas around it are major challenges for the climate researchers to model and understand it. It is also the centre of the tropical warm [...] Read more.

The Maritime Continent (MC) is positioned between the Asian and Australian summer monsoons zone. The complex topography and shallow seas around it are major challenges for the climate researchers to model and understand it. It is also the centre of the tropical warm pool of Southeast Asia (SEA) and therefore the MC gets extra attention of the researchers. The monsoon in this area is affected by inter-scale ocean-atmospheric interactions such as the El-Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Madden-Julian Oscillation (MJO). Monsoon rainfall in the MC (especially in Indonesia and Malaysia) profoundly exhibits its variability dependence on ocean-atmospheric phenomena in this region. This monsoon shift often introduces to dreadful events like biomass burning (BB) in Southeast Asia (SEA) in which some led to severe trans-boundary haze pollution events in the past. In this study, the BB episode of 2015 in the MC is highlighted and discussed. Observational satellite datasets are tested by performing simulations with the numerical weather prediction (NWP) model WRF-ARW (Weather Research and Forecast—Advanced research WRF). Observed and model datasets are compared to study the surface air temperature and precipitation (rainfall) anomalies influenced by ENSO, IOD, and MJO. Links amongst these influences have been recognised and the delayed precipitation of the regular monsoon in the MC due to their influence during the 2015 BB episode is explained and accounted for, which eventually led to the intensification of fire and a severe haze. Full article

(This article belongs to the Special Issue Monsoons)

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12 pages, 247 KiB

Open AccessArticle

Exposure to Outdoor Particles (PM_2.5) and Associated Child Morbidity and Mortality in Socially Deprived Neighborhoods of Nairobi, Kenya

by Thaddaeus Egondi, Remare Ettarh, Catherine Kyobutungi, Nawi Ng and Joacim Rocklöv

Atmosphere 2018, 9(9), 351; https://doi.org/10.3390/atmos9090351 - 11 Sep 2018

Cited by 21 | Viewed by 5498

Abstract

Exposure to air pollution is associated with adverse health outcomes. However, the health burden related to ambient outdoor air pollution in sub-Saharan Africa remains unclear. This study examined the relationship between exposure to outdoor air pollution and child health in urban slums of [...] Read more.

Exposure to air pollution is associated with adverse health outcomes. However, the health burden related to ambient outdoor air pollution in sub-Saharan Africa remains unclear. This study examined the relationship between exposure to outdoor air pollution and child health in urban slums of Nairobi, Kenya. We conducted a semi-ecological study among children under 5 years of age from two slum areas and exposure measurements of particulate matter (PM_2.5) at the village level were aligned to data from a retrospective cohort study design. We used logistic and Poisson regression models to ascertain the associations between PM_2.5 exposure level and child morbidity and mortality. Compared to those in low-pollution areas (PM_2.5 < 25 µg/m³), children in high-pollution areas (PM_2.5 ≥ 25 µg/m³) were at significantly higher risk for morbidity in general (odds ratio (OR) = 1.25, 95% confidence interval (CI): 1.11–1.41) and, specifically, cough (OR = 1.38, 95% CI: 1.20–1.48). Exposure to high levels of pollution was associated with a high child mortality rate from all causes (IRR = 1.22, 95% CI: 1.08–1.39) and respiratory causes (IRR = 1.12, 95% CI: 0.88–1.42). The findings indicate that there are associated adverse health outcomes with air pollution in urban slums. Further research on air pollution health impact assessments in similar urban areas is required. Full article

(This article belongs to the Special Issue Impacts of Air Pollution on Human Health)

20 pages, 4327 KiB

Open AccessArticle

Abrupt Climate Shift in the Mature Rainy Season of the Philippines in the Mid-1990s

by Lyndon Mark Olaguera, Jun Matsumoto, Hisayuki Kubota, Tomoshige Inoue, Esperanza O. Cayanan and Flaviana D. Hilario

Atmosphere 2018, 9(9), 350; https://doi.org/10.3390/atmos9090350 - 9 Sep 2018

Cited by 12 | Viewed by 7393

Abstract

A robust climate shift around 1993/1994 from early August to early September, which corresponds to the mature rainy season of the Philippines, was identified in stations located over the western coast of the country. The convection in the mature rainy season during 1994–2008 [...] Read more.

A robust climate shift around 1993/1994 from early August to early September, which corresponds to the mature rainy season of the Philippines, was identified in stations located over the western coast of the country. The convection in the mature rainy season during 1994–2008 (E2) was suppressed compared with 1979–1993 (E1). The possible role of the changes in the large-scale conditions and tropical cyclone (TC) activity were analyzed. The results show that the western North Pacific Subtropical High has extended further westward in E2 leading to an enhanced lower-level divergence and less moisture transport over the Philippines. The changes in the large-scale conditions, which featured a mid-tropospheric descent, a decrease in low-level relative humidity, an enhanced vertical zonal wind shear, and a decrease in the perturbation kinetic energy, also inhibited the synoptic-scale disturbances in the vicinity of the Philippines. In particular, fewer TCs developed and made landfall over the Philippines in E2. We also found inconsistent climate shifts in May, June, July, and September between the rainfall data from the stations and the Climate Prediction Center Merged Analysis of Precipitation, which highlights the importance of sub-seasonal analysis in decadal-to-interdecadal climate change studies. Full article

(This article belongs to the Special Issue Monsoons)

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16 pages, 1755 KiB

Open AccessArticle

Analysis and Estimation of Geographical and Topographic Influencing Factors for Precipitation Distribution over Complex Terrains: A Case of the Northeast Slope of the Qinghai–Tibet Plateau

by Weicheng Liu, Qiang Zhang, Zhao Fu, Xiaoyan Chen and Hong Li

Atmosphere 2018, 9(9), 349; https://doi.org/10.3390/atmos9090349 - 7 Sep 2018

Cited by 17 | Viewed by 3699

Abstract

Due to the complex terrain, sparse precipitation observation sites, and uneven distribution of precipitation in the northeastern slope of the Qinghai–Tibet Plateau, it is necessary to establish a precipitation estimation method with strong applicability. In this study, the precipitation observation data from meteorological [...] Read more.

Due to the complex terrain, sparse precipitation observation sites, and uneven distribution of precipitation in the northeastern slope of the Qinghai–Tibet Plateau, it is necessary to establish a precipitation estimation method with strong applicability. In this study, the precipitation observation data from meteorological stations in the northeast slope of the Qinghai–Tibet Plateau and 11 geographical and topographic factors related to precipitation distribution were used to analyze the main factors affecting precipitation distribution. Based on the above, a multivariate linear regression precipitation estimation model was established. The results revealed that precipitation is negatively related to latitude and elevation, but positively related to longitude and slope for stations with an elevation below 1700 m. Meanwhile, precipitation shows positive correlations with both latitude and longitude, and negative correlations with elevation for stations with elevations above 1700 m. The established multivariate regression precipitation estimating model performs better at estimating the mean annual precipitation in autumn, summer, and spring, and is less accurate in winter. In contrast, the multivariate regression mode combined with the residual error correction method can effectively improve the precipitation forecast ability. The model is applicable to the unique natural geographical features of the northeast slope of the Qinghai–Tibet Plateau. The research results are of great significance for analyzing the temporal and spatial distribution pattern of precipitation in complex terrain areas. Full article

(This article belongs to the Section Meteorology)

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14 pages, 4411 KiB

Open AccessArticle

Characteristic Analysis of the Downburst in Greely, Colorado on 30 July 2017 Using WPEA Method and X-Band Radar Observations

by Hao Wang, Venkatachalam Chandrasekar, Jianxin He, Zhao Shi and Lijuan Wang

Atmosphere 2018, 9(9), 348; https://doi.org/10.3390/atmos9090348 - 6 Sep 2018

Cited by 6 | Viewed by 3820

Abstract

As a manifestation of low-altitude wind shear, a downburst is a localized, strong downdraft that can lead to disastrous wind on the ground surface. For effective pre-warning and forecasting of downbursts, it is particularly critical to understand relevant weather features that occur before [...] Read more.

As a manifestation of low-altitude wind shear, a downburst is a localized, strong downdraft that can lead to disastrous wind on the ground surface. For effective pre-warning and forecasting of downbursts, it is particularly critical to understand relevant weather features that occur before and during a downburst process. It is important to identify the macroscopic features associated with the downburst weather process before considering fine-scale observations because this would greatly increase the accuracy and timeliness of forecasts. Therefore, we applied the wind-vector potential-temperature energy analysis (WPEA) method and CSU-CHILL X-band dual-polarization radar to explore the features of the downburst process. Here it was found that prior to the occurrence of the downburst of interest, the specific areas that should be monitored in future events could be determined by studying the atmospherically unstable areas using the WPEA method. Combining the WPEA method with dual-polarization radar observations, we can better distinguish the phase distribution of the hydrometeor in the process and greatly enhance the judgment of the possibility of the downburst. From exploration of the microphysical features of the downburst, we further found that ‘Z_dr (differential reflectivity) column’ can be regarded as an important early warning indicator of the location of the downburst. Finally, a schematic of the formation process of the downburst according to the analyses was produced. Full article

(This article belongs to the Section Meteorology)

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21 pages, 10188 KiB

Open AccessArticle

The Effect of Aerosol Radiative Heating on Turbulence Statistics and Spectra in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study

by Cheng Liu, Jianping Huang, Evgeni Fedorovich, Xiao-Ming Hu, Yongwei Wang and Xuhui Lee

Atmosphere 2018, 9(9), 347; https://doi.org/10.3390/atmos9090347 - 5 Sep 2018

Cited by 9 | Viewed by 9883

Abstract

Turbulence statistics and spectra in a radiatively heated convective boundary layer (CBL) under aerosol pollution conditions are less investigated than their counterparts in the clear CBL. In this study, a large-eddy simulation (LES) coupled with an aerosol radiative transfer model is employed to [...] Read more.

Turbulence statistics and spectra in a radiatively heated convective boundary layer (CBL) under aerosol pollution conditions are less investigated than their counterparts in the clear CBL. In this study, a large-eddy simulation (LES) coupled with an aerosol radiative transfer model is employed to determine the impact of aerosol radiative heating on CBL turbulence statistics. One-dimensional velocity spectra and velocity–temperature cospectra are invoked to characterize the turbulence flow in the CBL with varying aerosol pollution conditions. The results show that aerosol heating makes the profiles of turbulent heat flux curvilinear, while the total (turbulent plus radiative) heat flux profile retains the linear relationship with height throughout the CBL. The horizontal and vertical velocity variances are reduced significantly throughout the radiatively heated CBL with increased aerosol optical depth (AOD). The potential temperature variance is also reduced, especially in the entrainment zone and near the surface. The velocity spectral density tends to be smaller overall, and the peak of the velocity spectra is shifted toward larger wavenumbers as AOD increases. This shift reveals that the energy-containing turbulent eddies become smaller, which is also supported by visual inspection of the vertical velocity pattern over horizontal planes. The modified CBL turbulence scales for velocity and temperature are found to be applicable for normalizing the corresponding profiles, indicating that a correction factor for aerosol radiative heating is needed for capturing the general features of the CBL structure in the presence of aerosol radiative heating. Full article

(This article belongs to the Special Issue Large-Eddy Simulations (LES) of Atmospheric Boundary Layer Flows)

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30 pages, 8604 KiB

Open AccessArticle

A Comparison between 3DVAR and EnKF for Data Assimilation Effects on the Yellow Sea Fog Forecast

by Xiaoyu Gao, Shanhong Gao and Yue Yang

Atmosphere 2018, 9(9), 346; https://doi.org/10.3390/atmos9090346 - 3 Sep 2018

Cited by 15 | Viewed by 6646

Abstract

The data assimilation method to improve the sea fog forecast over the Yellow Sea is usually three-dimensional variational assimilation (3DVAR), whereas ensemble Kalman filter (EnKF) has not yet been applied to this weather phenomenon. In this paper, two sea fog cases over the [...] Read more.

The data assimilation method to improve the sea fog forecast over the Yellow Sea is usually three-dimensional variational assimilation (3DVAR), whereas ensemble Kalman filter (EnKF) has not yet been applied to this weather phenomenon. In this paper, two sea fog cases over the Yellow sea, one spread widely and the other spread narrowly along the coastal area, are studied in detail by a series of numerical experiments with 3DVAR and EnKF based on the Grid-point Statistical Interpolation (GSI) system and the Weather Research and Forecasting (WRF) model. The results show that the assimilation effect of EnKF outperforms that of 3DVAR: for the widespread-fog case, the probability of detection and equitable threat scores of the forecasted sea fog area are improved respectively by ~57.9% and ~55.5%; the sea fog formation of the other case completely mis-forecasted by 3DVAR was produced successfully by EnKF. These improvements of EnKF relative to 3DVAR benefit from its flow-dependent background error covariances, resulting in more realistic depiction of sea surface wind for the widespread-fog case and better moisture distribution for the other case in the initial conditions. More importantly, the correlation between temperature and humidity in the background error covariances of EnKF plays a vital role in the response of moisture to the assimilation of temperature, which leads to a great improvement in the initial moisture conditions for sea fog forecast. Extra sensitivity experiments of EnKF indicate that the forecast result is sensitive to ensemble inflation and localization factors, in particular, highly sensitive to the latter. Full article

(This article belongs to the Special Issue Storms, Jets and Other Meteorological Phenomena in Coastal Seas)

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18 pages, 11897 KiB

Open AccessArticle

Numerical Study on the Effect of Urbanization and Coastal Change on Sea Breeze over Qingdao, China

by Shangfei Hai, Yucong Miao, Lifang Sheng, Linbo Wei and Qing Chen

Atmosphere 2018, 9(9), 345; https://doi.org/10.3390/atmos9090345 - 3 Sep 2018

Cited by 15 | Viewed by 5431

Abstract

During the past few decades, rapid economic development occurred in Qingdao. Inevitably, human activities have caused great changes to the underlying surface, including urbanization and coastal change. Coastal change mainly refers to the expansion of the coastline to increase coastal land area. Sea-land [...] Read more.

During the past few decades, rapid economic development occurred in Qingdao. Inevitably, human activities have caused great changes to the underlying surface, including urbanization and coastal change. Coastal change mainly refers to the expansion of the coastline to increase coastal land area. Sea-land breeze (SLB) is important for local weather and the transport of air pollutant. However, the impact of human activities on the SLB over Qingdao is not yet clear. Thus, the weather research and forecasting (WRF) model is applied to study the effect of urbanization and coastal change on SLB. The study shows that urbanization strengthens the urban heat island (UHI) effect. Due to the expansions of urban area during past decades, sea breeze is strengthened before it passes through the urban areas. When it penetrates into the city, the inland progress of sea breeze is slowed down due to the UHI effect and stronger frictional force. Besides, the expansions of coastline can delay the SLB conversion time, lead to the changes in the sea breeze penetration path and the weakening of SLB intensity. Full article

(This article belongs to the Section Meteorology)

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18 pages, 8960 KiB

Open AccessArticle

How Sea Fog Influences Inland Visibility on the Southern China Coast

by Jianxiang Sun, Huijun Huang, Suping Zhang and Weikang Mao

Atmosphere 2018, 9(9), 344; https://doi.org/10.3390/atmos9090344 - 3 Sep 2018

Cited by 7 | Viewed by 6564

Abstract

Sea fog can lead to inland fog on the southern China coast, affecting visibility on land. To better understand how such fog influences inland visibility, we observed two sea-fog cases at three sites (over sea, at coast, and inland) and analyzed the results [...] Read more.

Sea fog can lead to inland fog on the southern China coast, affecting visibility on land. To better understand how such fog influences inland visibility, we observed two sea-fog cases at three sites (over sea, at coast, and inland) and analyzed the results here. Our analysis suggests four factors may be key: (1) The synoptic pattern is the decisive factor determining whether fog forms inland. First, sea fog and low clouds form when the synoptic pattern involves warm, moist air moving from a warmer sea-surface temperature (SST) region to a colder SST region near the coast. Then, inland fog tends to occur under this low-cloud background with relatively large horizontal-vapor transport. A greater horizontal-vapor transport results in denser fog with higher liquid-water content. Conversely, a strong horizontal advection of temperature with less horizontal-vapor transport can hinder inland-fog formation. (2) Local cooling (including ground radiative cooling) helps promote inland fog formation. (3) Fog formation requires low wind speed and small turbulent kinetic energy (TKE). The small TKE helps the vapor accumulate close to the surface and maintain the local cooling effect. (4) Fog formation is promoted by having the energy flux downward at night with the land surface cooling the atmosphere as well as having lower soil temperature and higher soil humidity. Full article

(This article belongs to the Special Issue Storms, Jets and Other Meteorological Phenomena in Coastal Seas)

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25 pages, 7815 KiB

Open AccessArticle

The Characteristics and Contributing Factors of Air Pollution in Nanjing: A Case Study Based on an Unmanned Aerial Vehicle Experiment and Multiple Datasets

by Shudao Zhou, Shuling Peng, Min Wang, Ao Shen and Zhanhua Liu

Atmosphere 2018, 9(9), 343; https://doi.org/10.3390/atmos9090343 - 2 Sep 2018

Cited by 37 | Viewed by 6176

Abstract

Unmanned aerial vehicle (UAV) experiments, multiple datasets from ground-based stations and satellite remote sensing platforms, and backward trajectory models were combined to investigate the characteristics and influential mechanisms of the air pollution episode that occurred in Nanjing during 3–4 December 2017. Before the [...] Read more.

Unmanned aerial vehicle (UAV) experiments, multiple datasets from ground-based stations and satellite remote sensing platforms, and backward trajectory models were combined to investigate the characteristics and influential mechanisms of the air pollution episode that occurred in Nanjing during 3–4 December 2017. Before the experiments, the position of the detector mounted on a UAV that was minimally disturbed by the rotation of the rotors was analyzed based on computational fluid dynamics (CFD) simulations. The combined analysis indicated that the surface meteorological conditions—high relative humidity, low wind speed, and low temperature—were conducive to the accumulation of PM_2.5. Strongly intense temperature inversion layers and the low thickness of the atmospheric mixed layer could have resulted in elevated PM_2.5 mass concentrations. In the early stage, air pollution was affected by the synoptic circulation of the homogenous pressure field and low wind speeds, and the pollutants mainly originated from emissions from surrounding areas. The aggravated pollution was mainly attributed to the cold front and strong northwesterly winds above 850 hPa, and the pollutants mostly originated from the long-distance transport of emissions with northwesterly winds, mainly from the Beijing‒Tianjin‒Hebei (BTH) region and its surrounding areas. This long-distance transport predominated during this event. The air pollution level and aerosol optical depth (AOD) were positively correlated with respect to their spatial distributions; they could reflect shifts in areas of serious pollution. Pollution was concentrated in Anhui Province when it was alleviated in Nanjing. Polluted dust, polluted continental and smoke aerosols were primarily observed during this process. In particular, polluted dust aerosols accounted for a major part of the transport stage, and existed between the surface and 4 km. Moreover, the average extinction coefficient at lower altitudes (<1 km) was higher for aerosol deposition. Full article

(This article belongs to the Special Issue Atmospheric Measurements with Unmanned Aerial Systems (UAS))

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19 pages, 5055 KiB

Open AccessArticle

Symmetry of Energy Divergence Anomalies Associated with the El Niño-Southern Oscillation

by Evan Kutta, Jason A. Hubbart, Timothy P. Eichler and Anthony R. Lupo

Atmosphere 2018, 9(9), 342; https://doi.org/10.3390/atmos9090342 - 1 Sep 2018

Cited by 1 | Viewed by 5050

Abstract

The El Niño-Southern Oscillation (ENSO) is a dominant source of global climate variability. The effects of this phenomenon alter the flow of heat from tropical to polar latitudes, resulting in weather and climate anomalies that are difficult to forecast. The current work quantified [...] Read more.

The El Niño-Southern Oscillation (ENSO) is a dominant source of global climate variability. The effects of this phenomenon alter the flow of heat from tropical to polar latitudes, resulting in weather and climate anomalies that are difficult to forecast. The current work quantified two components of the vertically integrated equation for the total energy content of an atmospheric column, to show the anomalous horizontal redistribution of surface heat flux anomalies. Symmetric and asymmetric components of the vertically integrated latent and sensible heat flux divergence were quantified using ERA-Interim atmospheric reanalysis output on 30 model layers between 1979 and 2016. Results indicate that asymmetry is a fundamental component of ENSO-induced weather and climate anomalies at the global scale, challenging the common assumption that each phase of ENSO is equal and opposite. In particular, a substantial asymmetric component was identified in the relationship between ENSO and patterns of extratropical climate variability that may be proportional to differences in sea surface temperature anomalies during each phase of ENSO. This work advances our understanding of the global distributions of source and sink regions, which may improve future predictions of ENSO-induced precipitation and surface temperature anomalies. Future studies should apply these methods to advance understanding and to validate predictions of ENSO-induced weather and climate anomalies. Full article

(This article belongs to the Section Meteorology)

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14 pages, 7673 KiB

Open AccessArticle

Tracking Jianghuai Cyclones in China and Their Climate Characteristics

by Lan Xia and Yue Zhou

Atmosphere 2018, 9(9), 341; https://doi.org/10.3390/atmos9090341 - 30 Aug 2018

Cited by 2 | Viewed by 3594

Abstract

A Jianghuai cyclone is an extratropical cyclone, which influences the middle and lower reaches of the Yangtze River and Huai River basins in China. According to the definition of Jianghuai cyclones, statistics of their climate characteristics from 1979 to 2010 are obtained by [...] Read more.

A Jianghuai cyclone is an extratropical cyclone, which influences the middle and lower reaches of the Yangtze River and Huai River basins in China. According to the definition of Jianghuai cyclones, statistics of their climate characteristics from 1979 to 2010 are obtained by an objective detection and tracking algorithm using ERA-Interim reanalysis data. The results show that the frequency of Jianghuai cyclones has a strong year-to-year variability but no obvious trend. Jianghuai cyclones are most frequent in May but fewest in December. As the cold air is active in spring, which interacts with the warm air from the southwest of the subtropical high at the Yangtze-Huai River region, it makes Jianghuai cyclones occur more frequently in this season. The main origins of Jianghuai cyclones are located in the Poyang Lake region, Dongting Lake region, and Dabie Mountain area. The maximum deepening rate of 0–2 hPa/6h is featured in 66.4% of Jianghuai cyclones. Over 40% of Jianghuai cyclones have a mean deepening rate of 0–1 hPa/6h. The lifetime of Jianghuai cyclones is short, mainly lasting for one to two days. In addition, background characteristics are compared between the formation, climax, and decaying periods of Jianghuai cyclones. Full article

(This article belongs to the Special Issue Storms, Jets and Other Meteorological Phenomena in Coastal Seas)

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13 pages, 929 KiB

Open AccessArticle

Size Distribution, Bioaccessibility and Health Risks of Indoor/Outdoor Airborne Toxic Elements Collected from School Office Room

by Zhi-Jie Tang, Xin Hu, Jun-Qin Qiao and Hong-Zhen Lian

Atmosphere 2018, 9(9), 340; https://doi.org/10.3390/atmos9090340 - 29 Aug 2018

Cited by 11 | Viewed by 3402

Abstract

20 sets of indoor and outdoor size-segregated aerosol (SSA) samples (180 foils) were collected synchronously by using two 8 Stage Non-Viable Cascade Impactor from an office room in the central region of the megacity-Nanjing, China in winter and spring in 2016. The mass [...] Read more.

20 sets of indoor and outdoor size-segregated aerosol (SSA) samples (180 foils) were collected synchronously by using two 8 Stage Non-Viable Cascade Impactor from an office room in the central region of the megacity-Nanjing, China in winter and spring in 2016. The mass size distribution of SSAs was bimodal for outdoor SSAs and unimodal for indoor in both winter and spring. The crustal elements, such as K, Ca, Mg and Fe, were mainly distributed in the coarse fractions of SSAs while toxic elements such as As, Cd, Pb and Sb were enriched more in the fine fractions in both winter and spring. Moreover, indoor/outdoor (I/O) concentration ratios of SSAs and inorganic elements indicated the penetration of outdoor fine fractions of SSAs into indoor air. As, Pb, V and Mn showed higher inhalation bioaccessibility extracted by the artificial lysosomal fluid (ALF); while V, As, Sr and Cd showed higher inhalation bioaccessibility using the simulated lung fluid (SLF), suggesting differences in elemental inhalation bioaccessibility between ALF and SLF extraction. There were similar potential carcinogenic and accumulative non-carcinogenic risks via inhalation exposure to indoor and outdoor particle-bound toxic elements based on their bioaccessible concentrations. Therefore, the potential health risks to human posed by toxic elements in office rooms cannot be neglected via inhalation exposure of the fine airborne particles. Full article

(This article belongs to the Section Air Quality)

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25 pages, 20471 KiB

Open AccessArticle

Dynamic Ensemble Analysis of Frontal Placement Impacts in the Presence of Elevated Thunderstorms during PRECIP Events

by Joshua Kastman, Patrick Market and Neil Fox

Atmosphere 2018, 9(9), 339; https://doi.org/10.3390/atmos9090339 - 29 Aug 2018

Cited by 2 | Viewed by 4872

Abstract

The Program for Research on Elevated Convection with Intense Precipitation (PRECIP) field campaign sampled 10 cases of elevated convection during 2014 and 2015. These intense observing periods (IOP) mostly featured well-defined stationary or warm frontal zones, over whose inversion elevated convection would form. [...] Read more.

The Program for Research on Elevated Convection with Intense Precipitation (PRECIP) field campaign sampled 10 cases of elevated convection during 2014 and 2015. These intense observing periods (IOP) mostly featured well-defined stationary or warm frontal zones, over whose inversion elevated convection would form. However, not all frontal zones translated as expected, with some poleward motions being arrested and even returning equatorward. Prior analyses of the observed data highlighted the downdrafts in these events, especially diagnostics for their behavior: the downdraft convective available potential energy (DCAPE) and the downdraft convective inhibition (DCIN). With the current study, the DCAPE and DCIN are examined for four cases: two where frontal motion proceeded poleward, as expected, and two where the frontal motions were slowed significantly or stalled altogether. Using the Weather Research and Forecasting (WRF) model, a multi-model ensemble was created for each of the four cases, and the best performing members were selected for additional deterministic examination. Analyses of frontal motions and surface cold pools are explored in the context of DCAPE and DCIN. These analyses further establish the DCAPE and DCIN, not only as a means to classify elevated convection, but also to aid in explaining frontal motions in the presence of elevated convection. Full article

(This article belongs to the Special Issue Precipitation: Measurement and Modeling)

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14 pages, 6308 KiB

Open AccessEditor’s ChoiceArticle

In-Cabin Vehicle Carbon Monoxide Concentrations under Different Ventilation Settings

by Kim N. Dirks, Nicholas Talbot, Jennifer A. Salmond and Seosamh B. Costello

Atmosphere 2018, 9(9), 338; https://doi.org/10.3390/atmos9090338 - 28 Aug 2018

Cited by 12 | Viewed by 4757

Abstract

This paper explores the impact of choice of ventilation setting (“window open”, “new (external) air” and “recirculate”) on in-vehicle carbon monoxide exposures for commuters travelling by car at different times of the day (morning, midday, and evening) and different seasons (warm and cool) [...] Read more.

This paper explores the impact of choice of ventilation setting (“window open”, “new (external) air” and “recirculate”) on in-vehicle carbon monoxide exposures for commuters travelling by car at different times of the day (morning, midday, and evening) and different seasons (warm and cool) in Auckland, New Zealand. Three near-identical vehicles travelled in close proximity to each other on the same three “loops” out and into the city three times a day, each with a different ventilation setting. Concentrations of carbon monoxide were recorded using portable monitors placed inside each of the vehicles. The season was not found to be a significant factor. However, mean concentrations varied across ventilation settings by the time of day, typically peaking during the morning commute. The mean concentrations were significantly different between ventilation settings, with the recirculate setting found to result in a higher in-vehicle concentration than either new air or windows open but also heavily dependent on the initial in-vehicle concentration. However, this setting was the most effective at avoiding concentration spikes, especially when idling at intersections; an isolated peak event reaching 170 ppm was observed with the “new air” setting when following immediately behind an old, poorly-tuned, and visibly-emitting vehicle. This study suggests that having the windows open is the best setting for maintaining low in-cabin air pollution levels but that recirculate should be used in anticipation of congested conditions. Full article

(This article belongs to the Special Issue Impacts of Air Pollution on Human Health)

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16 pages, 5607 KiB

Open AccessReview

The Concept of Large-Scale Conditioning of Climate Model Simulations of Atmospheric Coastal Dynamics: Current State and Perspectives

by Hans Von Storch, Leone Cavicchia, Frauke Feser and Delei Li

Atmosphere 2018, 9(9), 337; https://doi.org/10.3390/atmos9090337 - 27 Aug 2018

Cited by 3 | Viewed by 5378

Abstract

We review the state of dynamical downscaling with scale-constrained regional and global models. The methodology, in particular spectral nudging, has become a routine and well-researched tool for hindcasting climatologies of sub-synoptic atmospheric disturbances in coastal regions. At present, the spectrum of applications is [...] Read more.

We review the state of dynamical downscaling with scale-constrained regional and global models. The methodology, in particular spectral nudging, has become a routine and well-researched tool for hindcasting climatologies of sub-synoptic atmospheric disturbances in coastal regions. At present, the spectrum of applications is expanding to other phenomena, but also to ocean dynamics and to extended forecasting. Additionally, new diagnostic challenges are appearing such as spatial characteristics of small-scale phenomena such as Low Level Jets. Full article

(This article belongs to the Special Issue Storms, Jets and Other Meteorological Phenomena in Coastal Seas)

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16 pages, 1274 KiB

Open AccessReview

Traffic-Related Particulate Matter and Cardiometabolic Syndrome: A Review

by C. M. Sabbir Ahmed, Huanhuan Jiang, Jin Y. Chen and Ying-Hsuan Lin

Atmosphere 2018, 9(9), 336; https://doi.org/10.3390/atmos9090336 - 27 Aug 2018

Cited by 30 | Viewed by 7155

Abstract

Traffic-related particulate matter (PM) is a major source of outdoor air pollution worldwide. It has been recently hypothesized to cause cardiometabolic syndrome, including cardiovascular dysfunction, obesity, and diabetes. The environmental and toxicological factors involved in the processes, and the detailed mechanisms remain to [...] Read more.

Traffic-related particulate matter (PM) is a major source of outdoor air pollution worldwide. It has been recently hypothesized to cause cardiometabolic syndrome, including cardiovascular dysfunction, obesity, and diabetes. The environmental and toxicological factors involved in the processes, and the detailed mechanisms remain to be explored. The objective of this study is to assess the current scientific evidence of traffic-related PM-induced cardiometabolic syndrome. We conducted a literature review by searching the keywords of “traffic related air pollution”, “particulate matter”, “human health”, and “metabolic syndrome” from 1980 to 2018. This resulted in 25 independent research studies for the final review. Both epidemiological and toxicological findings reveal consistent correlations between traffic-related PM exposure and the measured cardiometabolic health endpoints. Smaller sizes of PM, particularly ultrafine particles, are shown to be more harmful due to their greater concentrations, reactive compositions, longer lung retention, and bioavailability. The active components in traffic-related PM could be attributed to metals, black carbon, elemental carbon, polyaromatic hydrocarbons, and diesel exhaust particles. Existing evidence points out that the development of cardiometabolic symptoms can occur through chronic systemic inflammation and increased oxidative stress. The elderly (especially for women), children, genetically susceptible individuals, and people with pre-existing conditions are identified as vulnerable groups. To advance the characterization of the potential health risks of traffic-related PM, additional research is needed to investigate the detailed chemical compositions of PM constituents, atmospheric transformations, and the mode of action to induce adverse health effects. Furthermore, we recommend that future studies could explore the roles of genetic and epigenetic factors in influencing cardiometabolic health outcomes by integrating multi-omics approaches (e.g., genomics, epigenomics, and transcriptomics) to provide a comprehensive assessment of biological perturbations caused by traffic-related PM. Full article

(This article belongs to the Special Issue Impacts of Air Pollution on Human Health)

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