Experimental Proof of Concept for the Hurricane Imaging Radiometer (HIRAD) Measurement of a Hurricane Ocean Surface Wind Speed Field

Round 1

Reviewer 1 Report

This is a necessary and useful attempt at extracting results from a less than perfect dataset; it should be published as being of importance to hurricane characterization and forecasting.

I have references that may improve the authors' perspective:  

- Scaling up: molecular to meteorological via symmetry breaking and statistical multifractality. Meteorology 2022, 1(1), 4-28;  doi:10.3390/meteorology1010003 
- Lovejoy, S; Schertzer, D. The Weather and Climate: Emergent Laws and Multifractal Cascades. Cambridge University Press, 2013.
- Schertzer, D; Lovejoy, S. Physical modeling and analysis of rain and clouds by anisotropic scaling multiplicative processes. J Geophys Res D, 92, 9693-9714 (1987).
- Davis, AB; Marshak, A; Catalan, RF; Wiscombe, WJ. Solar and laser beams in stratus clouds, fractals and multifractals in climate and remote sensing studies. Fractals - Interdiscipl J Complex Geom Nat 5, 129-166 (1997).

References 19 and 28 therein refer to analyses of GPS dropsondes over the ocean. My concern is that I cannot tell from reading the paper what kind of statistics they have used. Gaussians won't be accurate. Winds, temperatures and spectral lineshapes will all be affected. If the authors access the NASA ACCENT mission from 1999/2000, they will see that the WB57F flew over hurricane Floyd in September 2000. It climbed to avoid the cloud shield, which was well into the stratosphere. The ER-2 flew over Usha in 1994, and there was clear evidence from tracer observations that tropospheric air reached 20 km altitude above the hurricane (aka typhoon as it was in the Pacific).

 

Author Response

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Reviewer 2 Report

HIRAD is a new type of airborne remote sensor for hurricane wind speed and rainfall observation, has proved the great application potential of HIRAD through the research carried out in this paper. It shows the excellent performance of HIRAD and has more efficient observation ability than SFMR. HIRAD will be the preferred remote sensing equipment for high-precision hurricane wind speed observation in the future. However, the article still needs to be further considered and appropriately modified. The main modification suggestions are as follows:

1. A parameter x is omitted in fig.18 (a), such as y=0.9+3.4.

2. On October 17, the wind speed predicted by NHC was 50-60m/s, while in line 394, it was mentioned that the maximum wind speed obtained was 46m/s. Does it mean that the result in the text is too small?

3.In line 579, it is mentioned that the dynamic range 20 to>45m/s of wind speed retrieved by HIRAD has been tested, but in Section 2.5, It is recommended to provide a description of the algorithm dynamic range.

4. It can be seen from figure 8 (b) that a poor statistical registration has been improved after calibration. It is suggested to make a comparison between figure 8 (b) and the improved results.

5. In line 377, is it figure15a and figure15b, or figure13 and figure14?

6. In order to evaluate the observation accuracy of HIRAD more intuitively, it is recommended to list the absolute error, distance, observation time and other information between HIRAD and 13 dropsondes in the table.

7. In order to comprehensively measure the observation ability of the inversion algorithm during hurricanes, it is suggested to add more hurricane examples to further evaluate the algorithm.

8. During the hurricane, the wind speed is within 20m/s, or even lower. It is recommended to evaluate the observation accuracy of HIRAD under medium and low wind speed, so as to have a more comprehensive evaluation of HIRAD.

Author Response

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Reviewer 3 Report

Airborne hurricane surveillance is crucial to warnings issued by the NHC for ships at sea and for coastal regions of the Caribbean Sea, and the Atlantic and Pacific Oceans. This paper describes a new sensor technology known as HIRAD, which has the potential to be the next generation replacement for the SFMR. And authors present a reanalysis of HIRAD measurements over Hurricane Gonzalo on October 17, 2014, which demonstrates remarkable results. The paper is easy to read and gives a well-presented overview of related work. There are some minor concerns in the paper that need to be revised.

my concerns as follows:

1. Does HIRAD Instrument have a picture? This is helpful for readers to understand.

2. There is usually a conclusion at the end of the paper, which is suggested to be added.

Author Response

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