Turbulent kinetic energy dissipation rate in the lower troposphere using the 205 MHz radar at Kochi, India

Abstract

The Stratosphere–Troposphere (S–T) radar at Kochi (10.04° N, 76.33° E), India is the first radar operating at 205 MHz. At this location, the atmospheric background parameters such as atmospheric wind, temperature, and humidity show distinct changes from monsoon to winter season in the lower atmosphere. The general wind patterns differ significantly during different seasons, giving rise to differences in the characteristics of atmospheric turbulence parameters. S–T radar estimates of the Turbulence Kinetic Energy dissipation rate (ɛ) from ∼0.35–5 km for 722 days (2017–2019) are presented in this study to explain the seasonal variability of turbulence in terms of the background atmospheric conditions. Doppler spectral width measurements made by the S–T Radar are utilized to estimate ɛ. Non-turbulent contributions to the spectral broadening are calculated and separated from the observed spectral width before estimating ɛ. Turbulence in the planetary boundary layer is stronger and it generally decreases with height. Turbulence is highest during the monsoon season and lowest during winter. Under strong wind conditions, turbulence is stronger, and it is highly variable under weak wind conditions. Stronger turbulence is observed during monsoon season and is associated with higher wind speeds.