Quantifying the wave driving of the stratosphere

Abstract

The zonal-mean eddy heat flux is directly proportional to the wave activity that propagates from the troposphere into the stratosphere. This quantity is a simple eddy diagnostic which is calculated from conventional meteorological analyses. Because this "wave driving" of the stratosphere has a strong impact on the stratospheric temperature, it is necessary to compare the impact of the flux with respect to stratospheric radiative changes caused by greenhouse gas changes. Hence we must understand the precision and accuracy of the heat flux derived from our global meteorological analyses. Herein we quantify the stratospheric heat flux using five different meteorological analyses and show that there are 15% differences, on average, between these analyses during the disturbed conditions of the Northern Hemisphere winter. Such large differences result from the planetary differences in the stationary temperature and meridional wind fields. In contrast, planetary transient waves show excellent agreement among these five analyses, and this transient heat flux appears to have a long-term downward trend. Copyright 2000 by the American Geophysical Union.