Modulation of thermal structure in the upper troposphere and lower stratosphere (UTLS) region by inertia gravity waves: A case study inferred from simultaneous MST radar and GPS sonde observations

The observations of multiple layer structures in the MST radar backscattering echoes in the upper troposphere and lower stratosphere (UTLS) region are discussed in this paper. The fact remains same that the enhanced echoes seen in the radar backscattering are due to the strong positive and negative thermal gradients. Simultaneous observations of MST radar (1 hourly) and GPS sonde (6 hourly) over a tropical station Gadanki (13.5°N, 79.2°E) reveal the presence of 1.5-2 km vertical wavelength in the winds, temperature and radar backscattering echoes in the UTLS region during Indian summer monsoon (ISM). The analysis also reveals that the presence of inertia gravity wave (IGW) triggered due to tropical easterly jet (TEJ) associated with ISM is the prime candidate for the observed thermal gradients in the UTLS region.