Evaluation of MODIS and Himawari‐8 Low Clouds Retrievals Over the Southern Ocean With In Situ Measurements From the SOCRATES Campaign

• Published in: Earth and Space Science
• Main Authors: Litai Kang, Roger Marchand, William Smith
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2021
• Subjects: clouds; himawari‐8; MODIS; remote sensing; SOCRATES; southern ocean; Astronomy; QB1-991; Geology; QE1-996.5; Southern Ocean
• Online Access: https://doi.org/10.1029/2020EA001397; https://doaj.org/article/89c8e0c6fb304948ab5b12c711956a8f

Abstract Aircraft observations collected during the Southern Ocean Cloud Radiation Aerosol Transport Experimental Study in January‐February of 2018 are used to evaluate cloud properties from three satellite‐imager datasets: (1) the Moderate Resolution Imaging Spectroradiometer level 2 (collection 6.1) cloud product, (2) the CERES‐MODIS Edition 4 cloud product, and (3) the NASA SatCORPS Himawari‐8 cloud product. Overall the satellite retrievals compare well with the in situ observations, with little bias and modest to good correlation coefficients when considering all aircraft profiles for which there are coincident MODIS observations. The Himawari‐8 product does, however, show a statistically significant mean bias of about 1.2 μm for effective radius (re) and 2.6 for optical depth (τ) when applied to a larger set of profiles with coincident Himawari‐8 observations. The low overall mean‐bias in the re retrievals is due in part to compensating errors between cases that are non‐ or lightly precipitating, with cases that have heavier precipitation. re is slightly biased high (by about 0.5–1.0 μm) for non‐ and lightly precipitating cases and biased low by about 3–4 μm for heavily precipitating cases when precipitation exits near cloud top. The bias in non‐ and lightly precipitating conditions is due to (at least in part) having assumed a drop size distribution in the retrieval that is too broad. These biases in the re ultimately propagate into the retrieved liquid water path and number concentration.