Applying the Dark Target aerosol algorithm with Advanced Himawari Imager observations during the KORUS-AQ field campaign

• Main Authors: Gupta, Pawan, Levy, Robert C., Mattoo, Shana, Remer, Lorraine A., Holz, Robert E., Heidinger, Andrew K.
• Format: Text
• Language: unknown
• Published: EGU 2019
• Subjects: Aerosol Robotic Network
• Online Access: https://dx.doi.org/10.13016/m2gklw-btre; http://mdsoar.org/handle/11603/17225

Acknowledgements: This work was supported by the NASA ROSES program NNH17ZDA001N: Making Earth System Data Records for Use in Research Environments and NASA’s EOS program managed by Hal Maring. We thank the Space Science and Engineering Center (SSEC), University of Wisconsin-Madison for providing Himawari-8 data. We thank MCST for their efforts to maintain and improve the radiometric quality of MODIS data and LAADS/MODAPS for the continued processing of the MODIS products. The AERONET team (GSFC and site PIs) is thanked for the creation and continued stewardship of the sun photometer data record, which is available from http://aeronet.gsfc.nasa.gov (last access: 20 November 2019). Financial support: This research has been supported by the NASA (grant no. NNH17ZDA001N). : For nearly 2 decades we have been quantitatively observing the Earth's aerosol system from space at one or two times of the day by applying the Dark Target family of algorithms to polar-orbiting satellite sensors, particularly MODIS and VIIRS. With the launch of the Advanced Himawari Imager (AHI) and the Advanced Baseline Imagers (ABIs) into geosynchronous orbits, we have the new ability to expand temporal coverage of the traditional aerosol optical depth (AOD) to resolve the diurnal signature of aerosol loading during daylight hours. The Korean–United States Air Quality (KORUS-AQ) campaign taking place in and around the Korean peninsula during May–June 2016 initiated a special processing of full-disk AHI observations that allowed us to make a preliminary adoption of Dark Target aerosol algorithms to the wavelengths and resolutions of AHI. Here, we describe the adaptation and show retrieval results from AHI for this 2-month period. The AHI-retrieved AOD is collocated in time and space with existing AErosol RObotic NETwork stations across Asia and with collocated Terra and Aqua MODIS retrievals. The new AHI AOD product matches AERONET, and the standard MODIS product does as well, and the agreement between AHI and MODIS retrieved AOD is excellent, as can be expected by maintaining consistency in algorithm architecture and most algorithm assumptions. Furthermore, we show that the new product approximates the AERONET-observed diurnal signature. Examining the diurnal patterns of the new AHI AOD product we find specific areas over land where the diurnal signal is spatially cohesive. For example, in Bangladesh the AOD increases by 0.50 from morning to evening, and in northeast China the AOD decreases by 0.25. However, over open ocean the observed diurnal cycle is driven by two artifacts, one associated with solar zenith angles greater than 70° that may be caused by a radiative transfer model that does not properly represent the spherical Earth and the other artifact associated with the fringes of the 40° glint angle mask. This opportunity during KORUS-AQ provides encouragement to move towards an operational Dark Target algorithm for AHI. Future work will need to re-examine masking including snow mask, re-evaluate assumed aerosol models for geosynchronous geometry, address the artifacts over the ocean, and investigate size parameter retrieval from the over-ocean algorithm.