18 Oct 2023
 | 18 Oct 2023
Status: this preprint is currently under review for the journal AMT.

Retrievals of aerosol optical depth over the western North Atlantic Ocean during ACTIVATE

Leong Wai Siu, Joseph S. Schlosser, David Painemal, Brian Cairns, Marta A. Fenn, Richard A. Ferrare, Johnathan W. Hair, Chris A. Hostetler, Longlei Li, Mary M. Kleb, Amy Jo Scarino, Taylor J. Shingler, Armin Sorooshian, Snorre A. Stamnes, and Xubin Zeng


Aerosol optical depth was retrieved from two airborne remote sensing instruments, the Research Scanning Polarimeter (RSP) and Second Generation High Spectral Resolution Lidar (HSRL-2), during the NASA Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE). The field campaign offers a unique opportunity to evaluate an extensive 3-year dataset under a wide range of meteorological conditions from two instruments on the same platform. However, a longstanding issue in atmospheric field studies is that there is a lack of reference datasets for properly validating field measurements and estimating their uncertainties. Here we address this issue by using the triple collocation method, in which a third collocated satellite dataset from the Moderate Resolution Imaging Spectroradiometer (MODIS) is introduced for comparison. HSRL-2 is found to provide a more accurate retrieval than RSP over the study region. The error standard deviation of HSRL-2 with respect to the ground truth is 0.027. Moreover, this approach enables us to develop a simple, yet efficient, quality control criterion for RSP data. The physical reasons for the differences in two retrievals are determined to be cloud contamination, aerosols near surface, multiple aerosol layers, absorbing aerosols, non-spherical aerosols, and simplified retrieval assumptions. These results demonstrate the pathway for optimal aerosol retrievals by combining information from both lidar and polarimeter for future airborne and satellite missions.

Leong Wai Siu et al.

Status: open (until 24 Dec 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Leong Wai Siu et al.

Data sets

Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) NASA/LARC/SD/ASDC

MODIS/Terra Aerosol 5-Min L2 Swath 3km MODIS Science Team

MODIS/Aqua Aerosol 5-Min L2 Swath 3km MODIS Science Team

CALIPSO Lidar Level 3 Stratospheric Aerosol Profiles Standard V1-00 NASA/LARC/SD/ASDC

CALIPSO Lidar Level 3 Stratospheric Aerosol Profiles Standard V1-01 NASA/LARC/SD/ASDC

Leong Wai Siu et al.


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Short summary
A comprehensive 3-year aerosol dataset was collected from a recent field campaign, which offers a special opportunity to evaluate two remote sensing instruments, one lidar and the other polarimeter, on the same aircraft.  Special attention was paid to validate field data and their uncertainties when no reference dataset is available. A simple filter was developed to better quality control the polarimeter aerosol data. Physical reasons for the disagreement between two instruments were discussed.