Journal of Conference Abstracts

What is the Role of Adiabatic Mechanism in the Short Term Climate Variations?

Roman Bekryaev (bekryaev@aari.nw.ru)

Arctic and Antarctic Research Institute, 38 Bering str., St.-Petersburg, 199397, Russia

The general point of view connect all of the variation of the atmosphere global mean surface temperature with fluctuation of the heat fluxes. We assume that such short term variation may be partly a result of adiabatic vertical mixing.

A long-term (205 years) numerical integration of the MGO global atmospheric model T10-L14 and the analysis of experimental results were performed. Our main goal was to investigate the mechanisms of the low-frequency variability of the model global mean surface temperature.

Based on Walles et al. (1995) approach we have revealed the structures of the temperature on AT-1000 level and outgoing long-wave radiation fields on the top of the atmosphere. By the using of the monthly average data we have discovered COWL (Cold Ocean Warm Land) structures in the temperature fields well correlated to the global mean temperature r=0.7. In the outgoing long-wave radiation fields we have revealed Hadley structure that describe approximately 25% of the global mean temperature variability.

The enhance of the Hadley cell means (besides the radiation space redistribution) the grow of the vertical large-scale mixing. Such kind of mixing in turn may lead to the adiabatic grow of temperature in the low troposphere. We have found a good agreement between the theoretical results (sensitivity parameters for the adiabatic processes) and GCM long-term integration. In the moderate and high latitudes such agreement is especially well pronounced. Integration of the much more sophisticated T30-L14 model by using see surface temperature from 1979 to 1993 as bottom boundary conditions allows us to conclude that adiabatic mixing is a sufficient part the atmosphere global mean surface temperature variability.