Preprints
https://doi.org/10.5194/amt-2021-7
https://doi.org/10.5194/amt-2021-7

  10 Feb 2021

10 Feb 2021

Review status: this preprint is currently under review for the journal AMT.

Evaluation of satellite retrievals of liquid clouds from the GOES-13 Imager and MODIS over the midlatitude North Atlantic during NAAMES campaign

David Painemal1,2, Douglas Spangenberg1,2, William L. Smith Jr.2, Patrick Minnis1,2, Brian Cairns3, Richard H. Moore2, Ewan Crosbie1,2, Claire Robinson1,2, Kenneth L. Thornhill1,2, Edward L. Winstead1,2, and Luke Ziemba2 David Painemal et al.
  • 1Science Systems and Application Systems, Inc.
  • 2NASA Langley Research Center
  • 3NASA Goddard Institute for Space Studies

Abstract. Satellite retrievals of cloud droplet effective radius (re) and optical depth (t) from the Thirteenth Geostationary Operational Environmental Satellite (GOES-13), and the MOderate resolution Imaging Spectroradiometer (MODIS) onboard Aqua and Terra are evaluated with airborne data collected over the midlatitude boundary layer during the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES). The airborne dataset comprises in-situ re from the Cloud Droplet Probe (CDP) and remotely sensed re and t from the airborne Research Scanning Polarimeter (RSP). GOES-13 and MODIS (Aqua and Terra) re values are systematically greater than those from the CDP and RSP by at least 4.8 um (GOES-13) and 1.7 um (MODIS) despite relatively high linear correlations coefficients (r = 0.52–0.68). In contrast, the satellite t underestimates its RSP counterpart by −3.0, with r = 0.76–077. Overall, MODIS yields better agreement with airborne data than GOES-13, with biases consistent with those reported for subtropical stratocumulus clouds. While the negative bias in satellite t is mostly due to the retrievals having been collected in highly heterogeneous cloud scenes, the causes for the positive bias in satellite re, especially for GOES-13, are more complex. Although the high viewing zenith angle (~65°) and coarser pixel resolution for GOES-13 could explain a re bias of at least 0.7 um, the higher GOES-13 re bias relative to that from MODIS is likely rooted in other factors. In this regard, a near monotonic increase was also observed in GOES-13 re up to 1.0 um with satellite scattering angle (ϴ) over the angular range 116°–165°, that is, re increases toward the backscattering direction. Understanding the variations of re with ϴ will require the combined use of theoretical computations along with inter-comparisons of satellite retrievals derived from sensors with dissimilar viewing geometry.

David Painemal et al.

Status: open (until 09 Apr 2021)

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

David Painemal et al.

David Painemal et al.

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