Designating Airsheds in India for Urban and Regional Air Quality Management

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is well written and is relevant for Air Quality Management in Indian region. I have a few comments though that are needed to be addressed.

1.      Urban region as of 30 x 30 or 80 x 80 rectangular grid boxes (section 3.1): Given the nature of airflow in the area, is it the optimal way to define it in real world or the approach was only used to make analysis computationally efficient? It is neither based on administrative control or on pollutant flow patterns based on local topography.

2.    L126-127: “…Any of the contributions from outside these limits can be accounted for via boundary conditions in the chemical transport modeling…” how do author account for errors resulting from sudden change in spatial resolution (interpolation errors/limits) from global model output (~1 deg) to local CTM (0.01 deg) when doing airshed delineation?

3.    Seasonal nature of air pollution problem and its impact on airshed boundaries is not discussed in the manuscript.

Author Response

See the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study named "Designating Airsheds in India for Urban and Regional Air Quality Management" is very well written and addresses important issues that are strongly relevant to the scientific community. In particular, the author defines objectively airsheds for Indian cities, which are also extendable worldwide. I have only minor English corrections to suggest, and after those, the manuscript is recommended for acceptance.

Lines 40, 44 and 46: instead of commas, I suggest using ";".
Line 51: add AND in "... spatial, temporal, and judicial scales".
Line 104: replace "effect" with "affect"

 

 

Comments on the Quality of English Language

I have only minor English corrections to suggest, and after those, the manuscript is recommended for acceptance.

Lines 40, 44 and 46: instead of commas, I suggest using ";".
Line 51: add AND in "... spatial, temporal, and judicial scales".
Line 104: replace "effect" with "affect"

Author Response

See the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript describes an approach for constructing a system of airsheds for air quality management across India.  It builds on previous work covering urban-scale airsheds to come up with a manageable set of regional airsheds, considering meteorology, source type and distribution, and existing administrative units.  To strengthen their conclusions, the author could consider adding some of the technical details currently referenced in other manuscripts, but the tone is appropriate for this paper and audience.

 

In addition to these overall comments, I have some specific comments for the author to consider:

 

1. L114: 30 km x 30 km grids are somewhat small for air quality modeling, so it would be good to point out here that specification of boundary conditions is important, as stated in L127.

 

2. L264: Figure 3 is a good representation of differences across the airsheds.  To assist with interpretation, please add airshed numbers to one or both maps.

 

3. L311: These are not airsheds as defined in this paper, by meteorological and emissions factors, but rather administrative units based on multiple environmental characteristics.

 

Author Response

See the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Coordination and harmonization of air pollution control procedures are necessary to achieve realistic and effective results in terms of environmental protection. India is a large country divided into several states and districts. The main problem in harmonizing pollution control actions is the coordination of activities within states with different administrations, which are often controlled by different political groups or parties.

This work is valuable because it begins with a description of the current situation in India and describes 15 regional air sheds. According to the data reported in Figure 3, most PM2.5 pollution is attributed to residential and industrial power activities. Their control requires strong political and economic efforts, which may cause problems between different administrative bodies.

In the introduction, it is useful to provide some technical details about the models used and/or proposed. Because models are affected by uncertainty, the non-linearity of processes leading to PM2,5 could cause problems. Models are intended for emissions and transport, and they also include chemical transformation. Therefore, it is important to clarify the accuracy of the results obtained so far.

In addition, monitoring and assessment should follow common evaluation methods within and outside the designed airsheds. These are based on frequent quality control and quality assurance activities that are necessary at all levels.

At the end of introduction, the Author excludes notes on operational and legal aspects. However, these are crucial, so some paragraphs on that topic could be useful.

Although the major pollutant was PM2.5, other pollutants should also be mentioned. In the opinion of the referee, nitrogen dioxide and ozone should also be properly cited in the paper. Nitrogen oxides generate particulate matter and ozone.

A problem that should be considered is the effect of air pollution on the population. Some pollutants like nitrogen dioxide and primary PM2.5, show important concentration gradients; thus, models and observations should be oriented to a full protection of public health.

Lines 83-89 should recognize that models should be carefully checked for consensus among different administrative bodies. Otherwise, there is a strong risk that different results may lead to different control plans. It is suggested to include a brief description of the intended models with, possibly, uncertainty levels. These details should be provided on line 111.

Author should strongly reinforce the need for harmonization from national to local levels in terms of models, assessment and action plans.

Author Response

See the attached file.

Author Response File: Author Response.pdf