气候变化领域集成服务门户

Recent studies have focused on the role of cloud radiative effects (CRE) in governing the mean atmospheric circulation and its response to climate change. This study instead examines the role of CRE in climate variability in the extratropics. Cloud locking experiments are performed using the Community Earth System Model. In these experiments, CRE are scrambled, such that they maintain the same climatology but no longer match the model's dynamical fields. The results of these experiments indicate that high-frequency interactions between CRE and dynamics have a small (<= 5-10%) but statistically significant damping effect on the intensity of the extratropical storm tracks, particularly in the Southern Hemisphere. Individual midlatitude cyclones have decreased intensity and shorter lifetime. These effects arise largely from clouds' radiative modification of static stability below 700 hPa. The coupling among clouds, radiation, and dynamics thus has a modest but potentially important influence on the extratropical storm tracks.

Plain Language Summary Clouds are one of the largest sources of uncertainty in properly simulating Earth's climate system. Recent studies have shown that biases in clouds not only affect temperature but also can affect the representation of weather systems. This study focuses on the linkages between clouds and weather systems in the extratropics (poleward of 30 degrees latitude). The results show that if clouds are not properly represented, they can introduce small biases in the number, strength, and lifetime of the low-pressure systems that drive much of the precipitation at midlatitudes. Consequently, improving the representation of clouds in computer models may help to provide more accurate future projections of midlatitude weather systems.