Tracking ABL Height With 205 MHz VHF Radar: Diurnal and Seasonal Variability with Its Link to Convection.

This study demonstrates the potential of high-temporal-resolution VHF radar observations for capturing atmospheric boundary layer height (ABLH) variability that is difficult to resolve using conventional radiosonde profiles. A novel Normalised Standard Deviation Method (NSDM) was applied to radar observations from 2018–2024 over Cochin, India, using signal-to-noise ratio, wind variability and spectral width to characterise turbulence and estimate ABLH. The observations reveal clear diurnal and seasonal variability, with the deepest ABL development occurring during the pre-monsoon season and enhanced turbulence associated with daytime convection. Radar-derived ABLH estimates were compared with MERRA-2, IMDAA and ERA5 reanalysis datasets to assess their reliability and consistency. A strong inverse relationship between surface density and ABLH also indicates the potential of surface density as a useful proxy when profile observations are unavailable. The results demonstrate the value of VHF radar observations for investigating ABL and convective processes and for providing a high-resolution observational benchmark for the evaluation of numerical models and reanalysis products.