Publications

Chao, LW; Zelinka, MD; Dessler, AE (2024). Evaluating Cloud Feedback Components in Observations and Their Representation in Climate Models. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 129(2), e2023JD039427.

Abstract
This study quantifies the contribution of individual cloud feedbacks to the total short-term cloud feedback in satellite observations over the period 2002-2014 and evaluates how they are represented in climate models. The observed positive total cloud feedback is primarily due to positive high-cloud altitude, extratropical high- and low-cloud optical depth, and land cloud amount feedbacks partially offset by negative tropical marine low-cloud feedback. Seventeen models from the Atmosphere Model Intercomparison Project of the sixth Coupled Model Intercomparison Project are analyzed. The models generally reproduce the observed moderate positive short-term cloud feedback. However, compared to satellite estimates, the models are systematically high-biased in tropical marine low-cloud and land cloud amount feedbacks and systematically low-biased in high-cloud altitude and extratropical high- and low-cloud optical depth feedbacks. Errors in modeled short-term cloud feedback components identified in this analysis highlight the need for improvements in model simulations of the response of high clouds and tropical marine low clouds. Our results suggest that skill in simulating interannual cloud feedback components may not indicate skill in simulating long-term cloud feedback components. Cloud feedback-the radiative response of clouds to changes in temperature-is determined by the contributions from various cloud types and exhibits large uncertainty. Here, we use satellite observations to evaluate how the individual cloud feedback components in response to interannual variability are represented in the latest generation of climate models. The total cloud feedback is positive in the observations, mainly driven by changes in the altitude of high clouds, changes in the cloud cover over land, and changes in the reflectivity of high and low clouds over extratropical regions. The climate models were driven by observed sea-surface temperature, sea-ice conditions, and radiative forcing, so they can be directly compared to the observations. We found the models simulate a total cloud feedback that agrees with the observed positive total cloud feedback in general. However, the models consistently overestimate the decrease of cloud amount over land and in oceanic regions of tropical descent and consistently underestimate the increase of high-cloud altitude and the decrease of extratropical high- and low-cloud optical depth. Models that better simulate cloud feedback in response to short-term fluctuations do not perform better in simulating long-term cloud feedback under global warming. Individual short-term cloud feedback components in climate models are assessed by comparing against satellite observations Model biases are mainly driven by tropical marine low-cloud, high-cloud altitude, and extratropical high-cloud optical depth feedbacks Skill in simulating short-term cloud feedbacks is not correlated with skill in simulating long-term cloud feedbacks

DOI:
2169-8996

ISSN:
10.1029/2023JD039427