A novel method of estimating atmospheric boundary layer height using a 205 MHz VHF radar

The present study proposes a novel methodology for the estimation of atmospheric boundary layer height (ABLH) using data from a 205 MHz VHF (very high frequency) radar installed at the Advanced Centre for Atmospheric Radar Research, Cochin University of Science and Technology, India. Using a year-long dedicated experimental campaign involving collocated, concurrent radar and radiosonde operations in 2021, clear-sky days were identified for the analysis in order to avoid any further ambiguity in the results. The reference ABLH is derived from the mixing ratio and its gradient profiles from the radiosonde data. A new method has been devised to estimate the boundary layer height using the dataset from radar by combining three parameters, viz., signal-to-noise ratio, wind speed and wind direction. The ABLH is identified as that height at which the sum of the normalized standard deviations of three parameters peaks and subsequently decreases abruptly and substantially above it. This method has been verified against the ABLH estimated from four other variables from the radiosonde data, and a strong correlation (r = 0.91 at 99 % confidence level) between the ABLH derived from both methods has been obtained. This study extends ample opportunity to explore the high temporal variability such as the diurnal cycle of ABLH from the radar, unlike sparsely available radiosonde measurements.