Seasonal characteristics of storms over the Indian subcontinent

Abstract

AbstractStorms are convective cells responsible for the major fraction of convective precipitation. Here, the pre-monsoon and monsoon season characteristics of storms are reported at Lucknow, Patna, Bhopal, and Nagpur in India using equivalent radar reflectivity factor ($$\hbox {Z}_e$$ Z e ) given at these radar locations. It is observed that the lifetime, speed of propagation, area, volume, echo top height and thickness lie in ranges 0.3–3 h, 5–60 km $$\hbox {h}^{-1}$$ h - 1 , 4–184 $$\hbox {km}^2$$ km 2 , 8–1600 $$\hbox {km}^3$$ km 3 , 2–14 km, and 0.5–16 km respectively. For both seasons, the relationships between radar estimated rain volume (RERV; range $$10^4$$ 10 4 –$$10^7$$ 10 7 $$\hbox {m}^3$$ m 3 ) and area-time integral (ATI; range 1–100 $$\hbox {km}^2$$ km 2 h) are established which are considered as a representative of total precipitation resulted from an individual storm during its life cycle. The results from statistical analysis of RERV-ATI pairs suggest that storms at Lucknow have similar seasonal characteristics at 87% confidence interval while other locations exhibit dissimilarities. In addition, the vertical profiles of radar reflectivity (VPRRs) of storms are constructed at their life phases, namely cumulus, mature and dissipation. It is concluded that the vertical $$\hbox {Z}_e$$ Z e gradient in mixed-phase region (5–8 km) is lower (2–2.9 dBZ $$\hbox {km}^{-1}$$ km - 1 ) at cumulus and dissipation phases than at mature phase (3.6–4.4 dBZ $$\hbox {km}^{-1}$$ km - 1 ) in monsoon season. For pre-monsoon season, this gradient lies between 3.3–5.2 dBZ $$\hbox {km}^{-1}$$ km - 1 at mature phase. Our results are of great importance for advancing knowledge about storm-scale, which has implications in short-range weather forecasting as well as developing new convective parametrization schemes.