Estimating the Wind Dependency of Aerosol Optical Depth at Remote Oceanic Regions

Abstract

In this article, the applicability of India’s indigenously developed scatterometer, Scatsat-1 for marine aerosol characterization and wind dependency of aerosol optical depth (AOD) was investigated using 3 years of satellite data. Wind data from Scatsat-1 and AOD with its size fraction from SNPP VIIRS from 2017 to 2019 were used for the investigation. A technique has been demonstrated for identifying remote oceanic regions with mostly marine aerosol using certain criteria like distance from land, higher fraction of coarse AOD, lower variation of AOD with wind direction, and so forth. Daily wind and AOD from 2017 to 2019 were used for studying the relationship between wind speed and AOD at remote oceanic locations away from terrestrial and anthropogenic influence. Five regions of interest (ROIs) of 5° by 5° were identified in different oceanic regions for carrying out the regression analysis. A linear increase of coarse mode AOD and total AOD with an increase in wind speed was observed for all five remote locations while fine mode AOD was unrelated. The slope of the linear relation agreed with Kiliyanpilakkil and Meskhidze (2011) for intermediate wind values. The remote regions also had a lower variation of AOD with change in wind direction implying less transport of aerosol from nearby landmasses.

Keywords:

• Aerosol optical depth
• coarse mode AOD
• marine aerosol
• scatterometer

Acknowledgements

The authors express their gratitude to MOSDAC, Space Applications Centre, and NASA LAADS for Scatsat-1 and SNPP VIIRS data, respectively. The authors would like to take this opportunity to thank Director, Space Applications Centre for his active support and keen interest in this study.

Authors’ contributions

Debojyoti Ganguly did the conceptualization, methodology, analysis, investigation, and write up of manuscript. Dr. Mini Raman helped in the review and editing of the manuscript along with suggestions.

Disclosure statement

The authors report that there is no conflict of interest.

Data availability statement

Scatsat-1 wind data are available at www.mosdac.gov.in and SNPP VIIRS AOD and size fraction are available at www. earthdata.nasa.gov.