Long-term trend of tropopause Original Research Article

Due to the depletion of O3, less heat would be absorbed in the stratosphere and due to the increase in CO2 content, more heat would be trapped in the atmosphere. These effects may change the thermal structure of the tropopause region. Radiosonde observations taken during the past 9–32 years at four stations in India have been analysed to examine the long-term trend of tropopause height (TPH) and tropopause temperature (TPT). These stations are New Delhi (28°N, 77°E), Thiruvananthapuram (8°N, 76°E), Patna (25°N, 85°E) and Ahmedabad (24°N, 72°E). The results show that these parameters are changing over the years. The trend of change is not same throughout the period of study. Before and after around 1972, the trends are found to be different. Considering the whole period of data we find that TPH changes from +0.57 to + 3.25 %/decade, TPT has a decreasing trend for New Delhi (−0.57%/decade) and Thiruvananthapuram (−0.94%/decade) and an increasing trend for Patna (+2.12%/decade) and Ahmedabad (+1.22%/decade).