Proposals for an Indian standard tropical atmosphere up to 50 km

In an earlier report 1] the authors proposed an Indian Standard Tropical Atmosphere (ISTA1) from mean sea level to 20 km. This proposal describes adequately the mean conditions from 0° to about 30°N. The present work extends ISTA1 to the higher altitude of 50 km based oni. World Data Center A reports on Rocket firings 2],ii. M-100 rocket data for Thumba, India 3],iii. Northern Reference Atmospheres data of Cole and Kantor 4], andiv. Southern Reference Atmospheres data of Koshelkov 5].The proposed atmosphere, called ISTA7, has a sea level temperature of 30°C and a constant lapse rate of 6.5°C/km up to 16 km, as in ISTA1; from a temperature of -74°C at this altitude, there is a constant lapse rate of -2.3°C/km up to 46 km where the temperature is -5°C; the temperature remains constant thereafter up to 50 km. The fact that variations with longitude are weak except at very high latitudes 4], together with the fact that around 50 km, the temperature increases from low to high latitudes, lead us to propose a constant temperature of -5°C between 46 and 50 km, even though this temperature is slightly higher (by about 5°C) than the Thumba data.$\text{1}$/