Understanding the dynamic coupling between the stratosphere and troposphere and the exchange of water vapour, momentum, energy, and trace gases between these two layers have much significance in climate studies (Dessler et al., 2013; Solomon et al., 2010). Recent studies indicate that stratospheric water vapour and its variability play an important role in climate (Wang et al., 2017; Banerjee et al., 2019). Water vapour variability in the upper troposphere and lower stratosphere (UTLS) is closely related to the dynamics and thermo- dynamics of deep convective systems. Here, we focus on the stratosphere-troposphere exchange (STE) processes occurring through the tropical tropopause layer (TTL), the region between zero net radiative heating level to the highest level where convection reaches. Quantification of trace gases and mass flux through this region is a challenging task but is essential for understanding the chemistry and dynamics of STE. The different small-scale processes associated with TTL are also significant in STE. Turbulence in the atmosphere influences many processes such as mixing, cloud physics and dynamics, waves, general circulation of the atmosphere etc. Turbulence also impacts telecommunications, remote sensing, laser propagation, aviation etc and thus human activities are affected. The principal sources of turbulence in the troposphere are instabilities generated by wind shear, wave breaking, thermal convection etc. Turbulent kinetic energy dissipation rate (∈) and eddy diffusion coefficient (Km) are usually used as turbulence intensity measures. ∈ can be defined as the rate at which the amount of turbulence kinetic energy (TKE) is dissipated into heat by viscous forces at the Kolomogorov scale. In general, the estimation of turbulent parameters is not easy due to difficulties in measurements in the atmosphere. VHF radars are commonly used for studies of turbulence in the lower and middle atmosphere. The unique and novel stratosphere-troposphere (ST) wind profiler radar operating at 205 MHz at Kochi (10.04°N, 76.33°E), India provides accurate three-dimensional wind profiles for an altitude range of 315 m to 20 km, which is used to study the turbulence in the troposphere and lower stratosphere.

Team