Atmospheric turbulence characteristics in the troposphere and lower stratosphere of core monsoon zone

The geographical location of Central India (CI) is often under the influence of a variety of weather phenomena, viz., the Indian Summer Monsoon (ISM) and its associated low-pressure systems, heat waves, cold waves, and western disturbances. The present study investigates the Vertical Structure of atmospheric Turbulence (VST) in terms of the refractive index structure parameter (Cn2), in the troposphere and lower stratosphere over the core monsoon zone in the CI. Ten years (2011−2020) of GPS-radiosonde (GPS-RS) measurements and reanalysis datasets are employed to bring out the turbulence characteristics over the study region. The strong turbulence values below 12 km during the monsoon season are due to the frequent convective instabilities and higher vertical velocities, whereas contrasting VST is noted during non-monsoon seasons with significant turbulence intensities reaching up to the upper levels. The frequent convective instabilities and updrafts make the monsoon season's VST more homogeneous isotropic turbulence in character. Observed seasonal variability in VST is attributed mainly to moisture availability, thermal structure, presence of tri-model clouds, and a flip-flop pattern of mid-tropospheric wind circulation conditions. The early signature of the ISM onset with the higher cold cloud fraction is responsible for the observed weak turbulence zone centered at 14 km altitude. This striking weak Cn2 < 10−17 m−2/3 over the monsoon core zone VST is one of the most intriguing features observed in the present study. The signatures of various weather conditions such as heat waves, depressions, and cold waves are reflected in the observed variations of the VST during summer, monsoon, and winter, respectively. The variations in the pre/post VST and during specific weather events are attributed to the remarkable difference in relative humidity and temperature conditions. The present results provide a quantitative assessment of VST, including its seasonal evolution over Bhopal, using GPS-RS observations for the first time. The impact of better temporal/height sampling of GPS-RS data is evidenced by implementing the Thorpe method to estimate the outer scale of turbulence. The present analysis will also assist in designing experimental specifications for the proposed wind profiler in CI's Atmospheric Research Testbed for all-weather scale applications. •Predominent Gaussian (non-Gaussian) nature of VST is evident during monsoon (non-monsoon) season.•The large