Print Email Facebook Twitter A first comparison of TROPOMI aerosol layer height (ALH) to CALIOP data Title A first comparison of TROPOMI aerosol layer height (ALH) to CALIOP data Author Nanda, S. (TU Delft Atmospheric Remote Sensing) de Graaf, M. (Royal Netherlands Meteorological Institute (KNMI)) Veefkind, j. Pepijn (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)) Sneep, Maarten (Royal Netherlands Meteorological Institute (KNMI); S&T Corporation) Sun, J. (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)) Levelt, Pieternel Felicitas (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)) Date 2020 Abstract The TROPOspheric Monitoring Instrument (TROPOMI) level-2 aerosol layer height (ALH) product has now been released to the general public. This product is retrieved using TROPOMI's measurements of the oxygen A-band, radiative transfer model (RTM) calculations augmented by neural networks and an iterative optimal estimation technique. The TROPOMI ALH product will deliver ALH estimates over cloud-free scenes over the ocean and land that contain aerosols above a certain threshold of the measured UV aerosol index (UVAI) in the ultraviolet region. This paper provides background for the ALH product and explores its quality by comparing ALH estimates to similar quantities derived from spaceborne lidars observing the same scene. The spaceborne lidar chosen for this study is the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission, which flies in formation with NASA's A-train constellation since 2006 and is a proven source of data for studying ALHs. The influence of the surface and clouds is discussed, and the aspects of the TROPOMI ALH algorithm that will require future development efforts are highlighted. A case-by-case analysis of the data from the four selected cases (mostly around the Saharan region with approximately 800 co-located TROPOMI pixels and CALIOP profiles in June and December 2018) shows that ALHs retrieved from TROPOMI using the operational Sentinel-5 Precursor Level-2 ALH algorithm is lower than CALIOP aerosol extinction heights by approximately 0.5km. Looking at data beyond these cases, it is clear that there is a significant difference when it comes to retrievals over land, where these differences can easily go over 1km on average. To reference this document use: http://resolver.tudelft.nl/uuid:b0bb4a45-958a-4a46-811f-a50e8e9e65ab DOI https://doi.org/10.5194/amt-13-3043-2020 ISSN 1867-1381 Source Atmospheric Measurement Techniques, 13 (6), 3043-3059 Part of collection Institutional Repository Document type journal article Rights © 2020 S. Nanda, M. de Graaf, j. Pepijn Veefkind, Maarten Sneep, J. Sun, Pieternel Felicitas Levelt Files PDF amt_13_3043_2020.pdf 19.33 MB Close viewer /islandora/object/uuid:b0bb4a45-958a-4a46-811f-a50e8e9e65ab/datastream/OBJ/view