Estimation of uncertainty in surface air temperature climatic trends related to the internal dynamics of the atmosphere

Abstract

The variability of zonal trends of surface air temperature for the period 1979–2012 is analyzed using ensemble simulations with a general atmospheric circulation model (AGCM) with identical prescribed conditions at the lower boundary of the atmosphere and different initial conditions. It is shown that the dependence of the variability of intra-ensemble zonal temperature trends on the variability of zonal fluctuations of temperature anomalies (associated with the internal variability of atmospheric circulation in the AGCM) is described quite well in terms of the stationary stochastic process model. In such a model, the dependence of the standard deviation of intra-ensemble trends can be approximated by a linear function of the standard deviation of temperature fluctuations, which agrees well with the AGCM results.