Measurements of Raindrop Size Distribution Using Collocated X- and Ka-Band Radars in the Western Ghats

Multifrequency radar retrievals of precipitation characteristics are more accurate than single-frequency radars. This study focuses on retrieving the raindrop size distribution parameters (e.g., median volume drop diameter;
$D_{\mathbf {0}}$
and normalized intercept parameter,
$N_{\mathbf {w}}$
) from X- and Ka-band radars using the dual-frequency ratio (DFR) technique and quantitatively assesses the retrieved parameter with co-located Joss-Waldvogel Disdrometer (JWD) and global precipitation measurement (GPM) observations. Both radars are collocated at Mandhardev (
$18.04~^{\circ }$
N,
$73.86~^{\circ }$
E, ~1.3 km AMSL), a high-altitude site in the Western Ghats (WGs), India. The T-matrix scattering simulations are performed at X- and Ka-band to establish the relationship between DFR and
$D_{\mathbf {0}}$
. Using
$D_{\mathbf {0}}$
, an iterative calculation is performed to calculate the
$N_{\mathbf {w}}$
. The
$D_{\mathbf {0}}$
values derived from DFR demonstrate good agreement with the disdrometer measurements, while compared to GPM observations, they reveal similar vertical variations but differing magnitudes.