Revealing differences in GCM representations of low clouds

By B. Medeiros, Bjorn Stevens. 2011

148 citations recorded by the source corpus.

Aquaplanet configurations of four atmospheric general circulation models (GCMs) are compared with standard, Earth-like configurations and observations. The focus here is on tropical, low-level clouds, which have been identified as important for estimates of climate sensitivity. Investigating the distribution of the monthly mean vertical velocity and lower-tropospheric stability, the aquaplanets are seen to capture the core of the distribution of the more Earth-like configurations, whose distributions are, in turn, similar to that of reanalysis data. By conditionally sampling over these distributions, low-cloud regimes are defined, separating shallow cumulus convection from stratocumulus. Within each regime, the GCMs produce similar large-scale environments, yet disparate depictions of the clouds. Aquaplanets lack stratocumulus because of their zonally symmetric boundary conditions, but produce extensive trade-wind regions populated by shallow cumulus clouds just like those in the Earth-like setting. The analysis shows that aquaplanets can be compared with observations, just as well as the Earth-like configuration, with the added ability to focus on particular regimes without complications from geographical or temporal biases.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/4c53d36ed72ccf215f0767c4c9d1af278a3160d2

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Citations in the corpus

The Evolution of Climate Sensitivity and Climate Feedbacks in the Community Atmosphere Model (2012, background): “%) is smaller than reanalyses (6%), consistent with model biases that result in breakup of stratocumulus too quickly (Medeiros and Stevens 2011).”
On Constraining Estimates of Climate Sensitivity with Present-Day Observations through Model Weighting (2011, background): “In nature, boundary layer clouds in subsiding regions over the oceans are further correlated (Medeiros and Stevens 2011) with lower-tropospheric thermodynamic stability (LTS) (see Bretherton and Wyant 1997; Klein and Hartmann 1993), here defined as the difference in the potential temperature at…”
Some issues in uncertainty quantification and parameter tuning: a case study of convective parameterization scheme in the WRF regional climate model (2011, methodology): “…applied MVFSA to optimize six parameters related to the cloud process in a Global Climate Model (GCM) because cloud processes play a critical role in the hydrological cycle and uncertainty of climate response to doubling of CO2 forcing (Colman, 2003; Webb et al., 2006; Medeiros and Stevens, 2011).”
Higher-Order Turbulence Closure and Its Impact on Climate Simulations in the Community Atmosphere Model (2013, methodology): “Sampling criteria used to segregate stratocumulus, transitional clouds, and trade wind cumulus based on that of Medeiros and Stevens (2011).”