Space-Borne Dual Frequency Radar Observations of Precipitation Microphysics of Extremely Severe and Long Lived Cyclonic Storm ‘BIPARJOY’
摘要
Observations of Dual-frequency Precipitation Radar (DPR) on-board Global Precipitation Measurement (GPM) over an extremely severe cyclonic storm that formed over the Arabian Sea in the month of June 2023 are used to investigate the spatial pattern of microphysical processes of precipitating clouds embedded in the eye-wall, inner and outer rainband regions of the cyclone. The diameter of the eye of the cyclone is observed to be around 50 km with echo tops reaching as high as 15 km near the eye-wall region. The spatial and vertical distribution of radar reflectivity (Ze), median drop diameter (Dm), drop concentration (NW) and latent heating during various stages of the cyclone are explored. The structural and microphysical differences in the eyewall, inner and outer rainbands are investigated using composite analysis. The contour frequency by altitude diagram analysis revealed that the Dm of about 1.75–2 mm dominates at the lower altitude levels (below 5 km) in the inner rainband region of the cyclone whereas Dm of about 1.5–1.75 mm (1.25–1.5 mm) found to be dominant in the eye wall (outer rainband) regions. It is also noted that the precipitation clouds embedded in the eye-wall region has relatively large drop concentration followed by inner and outer rainbands. Results indicate that the maximum deviation of weighted number concentration is 4(5) % higher in the inner (outer) rainband at 6 km, compared to the eyewall region in the case of the ‘BIPARJOY’ cyclone. The mean values of Dm in the eyewall, inner and outer rainband at the near-surface level (at 2 km) are found to be around 1.5, 1.75, and 1.25 mm, respectively. The mean latent heating profiles have shown the bimodal distribution with a primary peak around 4 km in both eye-wall and inner rain band regions. It is noted that the magnitude of latent heating in the eye-wall region is ~ 2.5 times that of the inner rainband region. The analysis of microphysical processes revealed that the coalescence is the dominant process in the eyewall and inner rainband regions, whereas the simultaneous presence of coalescence and break-up processes are observed in the outer rainband region. The significance of the present study lies in bringing out the spatial pattern of microphysical processes in the different regions such as eye-wall, inner and outer rainband of the cyclone and in discussing the potential physical mechanisms governing these processes.