Tropical Tropopause Dynamics

In recent years “Tropical Tropopause” has been receiving immense scientific interest because of its sensitivity to anthropogenic activities leading to climate change. The focus is mainly on chemistry, dynamics, radiation as well as transport within the Tropical Tropopause region/layer (TTL). There is an immediate need to link the TTL processes to climate, which requires the inclusion of radiation and chemistry in the conceptual framework. Convection in the tropics plays a key role in redistributing trace gases and aerosols in the upper Troposphere–lower stratosphere (UTLS) region, and the interaction between cloud dynamics, radiation and microphysics is of fundamental importance in these processes. Among these the convective detrainment and the effect of overshooting convection on the heat balance of the TTL remain elusive. With a view to address this important and complex interplay, particularly over Indian region, a focused field experiment “Tropical Tropopause Dynamics (TTD)” has been formulated under the CAWSES-India program of ISRO since 2004. The science objectives being addressed are:

(i) Temporal evolution of TTL on shorter time scales and its association with convection
(ii) Characteristics of turbulence structure in the troposphere/TTL at shorter time scales
(iii) Effect of cirrus in modulating the thermal structure of TTL
(v) Association between cirrus, convection and turbulence
(iv) Role of waves in modulating cirrus and thermal structure.

As part of this program, SPL and NARL jointly conducted scientific experiments at Trivandrum [8.5°N, 77°E] and Gadanki [13.5°N, 79.2°E] using balloons, lidar and radars during the period December 2010 to March 2014 [40 campaigns]. Simultaneous radiosonde soundings were carried out from both stations, at 3 h interval for three consecutive days in each month at 02:30, 05:30, 08:30, 11:30, 14:30, 17:30, 20:30 and 23:30 IST.

For further details on the data, please contact: Dr. S. V. Sunilkumar ( This email address is being protected from spambots. You need JavaScript enabled to view it.)