Influence of processes in stratosphere upon the temperature at the tropopause and below

Abstract:

Both total contents and vertical profiles of stratospheric aerosol and ozone are negatively correlated, which is caused by radiative processes that directly influence the temperature above the tropopause - an important climatic characteristic. The described interaction of the processes illustrating the influence of the stratospheric aerosol upon air temperature is under consideration in the presentation focused on climate changes in the temperature of the tropopause and below provided by balloon-borne radiosonde observations.

Changes in mean annual tropopause temperatures measured by radiosondes at 1200Z and 0000Z GMT at more than 200 stations show that the day and night temperatures typically differing more than 0.5 degree for the 25 years (1977 through 1992) begin converging in the Post-Pinatubo period from 20mb down to the 500 or 700 MB level becoming equal to each other. For example, the convergence took place over the largest part of the United States in approximately 1993 (slightly later in Alaska and Western Canada) and in most cases 0000Z and 1200Z GMT temperatures remain equal till present time.

The phenomenon of converging day and night temperatures felt deep in the atmosphere is very interesting and somewhat surprising, but there is a logical explanation for the convergence. The day temperature at 100 mb was higher than the night temperature because of radiative heating due to the joint influence of stratospheric aerosol and ozone absorbing radiation from the Sun. The merge of two temperatures means cooling of the daytime temperature when excessive heating due to stratosphere aerosol has gone away .

When the daytime temperature at the tropopause decreases, the air temperature in the upper part of the troposphere adjusts to lower temperature at 100 mb due to mixing spreading the convergence to 500 - 700 mb. In some cases mixing in the troposphere reaches at least the lowest level of observations at 850 mb. This can explain that the surface temperature in Greenland and its vicinity does not follow a predominant warming climate trend in air surface temperature.

If our atmosphere is entering a new and unknown era of climate change, where will it go from here?

Figure. Alaska and Western Canada 00z and 12z Temperature Differences.