Preprints
https://doi.org/10.5194/amt-2021-392
https://doi.org/10.5194/amt-2021-392

  23 Dec 2021

23 Dec 2021

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

The Surface Longwave Cloud Radiative Effect derived from Space Lidar Observations

Assia Arouf1, Hélène Chepfer1, Thibault Vaillant de Guélis2,3, Marjolaine Chiriaco4, Matthew D. Shupe5,6, Rodrigo Guzman1, Artem Feofilov1, Patrick Raberanto7, Tristan S. L’Ecuyer8, Seiji Kato3, and Michael R. Gallagher5,6 Assia Arouf et al.
  • 1LMD/IPSL, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris, ENS, PSL Université, CNRS, Palaiseau France
  • 2Science Systems and Applications, Inc., Hampton, Virginia, USA
  • 3NASA Langley Research Center, Hampton, Virginia, USA
  • 4LATMOS/IPSL, UVSQ, Université Paris-Saclay, Sorbonne Université, CNRS, 78280, Guyancourt, France
  • 5Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
  • 6NOAA Physical Sciences Laboratory, Boulder, Colorado, USA
  • 7LMD/IPSL, CNRS, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris, ENS, PSL Université, Palaiseau France
  • 8Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, USA

Abstract. Clouds warm the surface in the longwave (LW) and this warming effect can be quantified through the surface LW cloud radiative effect (CRE). The global surface LW CRE is estimated using long-term observations from space-based radiometers (2000–2021) but has some bias over continents and icy surfaces. It is also estimated globally using the combination of radar, lidar and space-based radiometer over the 5–year period ending in 2011. To develop a more reliable long time series of surface LW CRE over continental and icy surfaces, we propose new estimates of the global surface LW CRE from space-based lidar observations. We show from 1D atmospheric column radiative transfer calculations, that surface LW CRE linearly decreases with increasing cloud altitude. These computations allow us to establish simple relationships between surface LW CRE, and five cloud properties that are well observed by the CALIPSO space-based lidar: opaque cloud cover and altitude, and thin cloud cover, altitude, and emissivity. We use these relationships to retrieve the surface LW CRE at global scale over the 2008–2020 time period (27 Wm−2). We evaluate this new surface LW CRE product by comparing it to existing satellite-derived products globally on instantaneous collocated data at footprint scale and on global averages, as well as to ground-based observations at specific locations. Our estimate appears to be an improvement over others as it appropriately capture the surface LW CRE annual variability over bright polar surfaces and it provides a dataset of more than 13 years long.

Assia Arouf et al.

Status: open (until 28 Jan 2022)

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Assia Arouf et al.

Assia Arouf et al.

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Short summary
We proposed new estimates of the surface longwave (LW) cloud radiative effect (CRE) derived from observations collected by a space-based lidar on board of CALIPSO satellite and radiative transfer computations. Our estimate appears to be an improvement over others as it appropriately capture the surface LW CRE annual variability over bright polar surfaces and it provides a dataset of more than 13 years long.