CLIMATE IMPLICATIONS OF OBSERVED CHANGES IN OZONE VERTICAL DISTRIBUTIONS AT MIDDLE AND HIGH-LATITUDES OF THE NORTHERN-HEMISPHERE

Ozone soundings at middle and high latitudes of the Northern Hemispher e during recent decades indicate a decreasing trend in the lower strat osphere and an increasing trend in the troposphere especially at the u pper troposphere. Changes in the O3 vertical distribution can change t he radiative forcing (solar and longwave radiation) to the troposphere -surface system with climate implications. Here, we use the O3 soundin gs at seven middle and high latitudes stations to study its variations in the last few decades and discuss the climate implications in the c ontext of increasing other greenhouse gases CO2, CH4, CFC-11, CFC-12 a nd N2O. The results suggest that changes in O3 vertical distribution c an perturb substantially the radiative forcing, in particular at the m iddle latitudes where the tropospheric increases can induce a positive radiative forcing (warming) with magnitude comparable to that due to increasing these other greenhouse gases.