Observations and Simulation of the Variability of the Stratosphere and Troposphere in January

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  • 1 National Center for Atmospheric Research, Boulder, CO 80307
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Abstract

A sufficiently long record of satellite data is now available for the upper stratosphere to make preliminary estimates of the interannual variability of the circulation possible. Global analyses from the lower troposphere to the stratopause for 7 Januaries (1979–85) are used to calculate the ensemble means of the geopotential height field and the zonally averaged temperature and zonal wind fields, together with their daily and interannual variability. These statistics are compared with corresponding statistics from a general circulation model experiment.

The model generally simulates the ensemble mean fields reasonably well although several differences are found when the variability of the model is compared to the observations. In particular, the interannual variability of the model is considerably larger than observed in the high latitude winter stratosphere. This excessive variability may be related to the perpetual January methodology used in the model simulation. Statistical significance testing of the differences between the model and the observations is not performed because of uncertainties in the quality of the observational interannual variability estimates.

Abstract

A sufficiently long record of satellite data is now available for the upper stratosphere to make preliminary estimates of the interannual variability of the circulation possible. Global analyses from the lower troposphere to the stratopause for 7 Januaries (1979–85) are used to calculate the ensemble means of the geopotential height field and the zonally averaged temperature and zonal wind fields, together with their daily and interannual variability. These statistics are compared with corresponding statistics from a general circulation model experiment.

The model generally simulates the ensemble mean fields reasonably well although several differences are found when the variability of the model is compared to the observations. In particular, the interannual variability of the model is considerably larger than observed in the high latitude winter stratosphere. This excessive variability may be related to the perpetual January methodology used in the model simulation. Statistical significance testing of the differences between the model and the observations is not performed because of uncertainties in the quality of the observational interannual variability estimates.

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