Cloud and radiation feedbacks resulting from changes in midlatitude storms
Abstract
Cloud-climate feedback is considered a major reason for the large range of uncertainty in model simulations of climate warming. Since cloud and radiation feedbacks derive from the interactions between clouds and atmospheric dynamic and thermodynamic processes, the construction of observational constraints related to cloud feedback processes should concentrate on cloud and radiation changes with dynamic and thermodynamic conditions. Recent studies find pronounced shifts in the distribution and strength of midlatitude dynamic regimes in both current-climate observations and GCM climate simulations. Such shifts would produce strong signatures in the properties of the cloud and radiation fields leading to potentially significant cloud and radiation climate feedbacks. In this study, satellite retrievals of cloud properties and radiation fields are combined with meteorological observations of midlatitude storm properties to examine changes in midlatitude cloud and radiation with atmospheric dynamics. The results show that in the summer season the shortwave radiation differences between strong and weak midlatitude storms can reach values as high as 180 W/m2. These differences are due to large cloud cover and cloud optical depth shifts with storm strength. The longwave radiation differences between strong and weak storms are smaller but still significant and are of similar strength in both the summer and winter seasons. These results indicate that even small shifts in the distrubution of midlatitude dynamic regimes with ciimate change would produce large cloud and radiation feedbacks.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....2055T