28 Mar 2023
 | 28 Mar 2023

Examining cloud vertical structure and radiative effects from satellite retrievals and evaluation of CMIP6 scenarios

Hao Luo, Johannes Quaas, and Yong Han

Abstract. Clouds exhibit a wide range of vertical morphologies that are regulated by distinct atmospheric dynamics/thermodynamics and are related to a diversity of microphysical properties and radiative effects. In this study, the new CERES-CloudSat-CALIPSO-MODIS (CCCM) RelD1 dataset is used to investigate the morphology and spatial distribution of different CVS types during 2007–2010. The combined active and passive satellites provide a more precise CVS than only based on passive imagers or microwave radiometers. We group the clouds into 12 CVS classes based on how they are located or overlapping in three standard atmospheric layers with pressure thresholds of 440 and 680 hPa. For each of the 12 CVS types, the global average cloud radiative effects (CREs) at the top of the atmosphere, within the atmosphere and at the surface, as well as the cloud heating rate (CHR) profiles are examined. The observations are subsequently used to evaluate the variations in total, high-, middle- and low-level cloud fractions in CMIP6 models. The ‘historical’ experiment during 1850–2014 and two scenarios (ssp245 and ssp585) during 2015–2100 are analysed. The observational results show a substantial variance in the spatial pattern among different CVS types, with the greatest contrast between high and low clouds. Single-layer cloud fraction is almost four times larger on average than multi-layer cloud, with significant geographic differences associated with clearly distinguishable regimes, showing that overlapping clouds are regionally confined. The global average CREs reveal that four types of CVS warm the planet while eight of them cool it. The longwave component drives the net CHR profile, and the CHR profiles of multi-layer clouds are more curved and intricate than those of single-layer clouds, resulting in complex thermal stratifications. According to the long-term analysis from CMIP6, the projected total cloud fraction decreases faster over land than over the ocean. The high clouds over the ocean increase significantly, but other types of clouds over land and ocean continue to decrease, helping to offset the decrease in oceanic total cloud fraction. Moreover, it is concluded that the spatial pattern of CVS types may not be significantly altered by climate change, and only the cloud fraction is influenced. Our findings suggest that long-term observed CVS should be emphasized in the future to better understand CVS responses to anthropogenic forcing and climate change.

Hao Luo et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-453', Anonymous Referee #1, 18 Apr 2023
  • RC2: 'Comment on egusphere-2023-453', Anonymous Referee #2, 20 Apr 2023

Hao Luo et al.


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Short summary
Clouds exhibit a wide range of vertical structures with varying microphysical and radiative properties. We show a global survey of spatial distribution, vertical extent, and radiative effect of various classified cloud vertical structures using joint satellite observations from the new CCCM datasets during 2007–2010. Moreover, the long-term trends in CVS are investigated based on different CMIP6 future scenarios to capture the cloud variations with different, increasing anthropogenic forcings.