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Nat Hazards (2017) 85:267282
DOI 10.1007/s11069-016-2561-0
ORIGINAL PAPER
J. Pal1 P. P. Debnath1 S. Guhathakuran1 S. Chaudhuri1
Received: 26 May 2014 / Accepted: 28 August 2016 / Published online: 3 September 2016 Springer Science+Business Media Dordrecht 2016
Abstract The cloudburst is dened as a heavy downpour at a very high rainfall rate over small spatio-temporal scale. The Indian states of Uttarakhand (30150N; 79150E) and
Himachal Pradesh (32290N; 75100E) are prone to cloudburst due to its geographical setup. The large-scale monsoon ow along with elevated orography makes cloudburst phenomena frequent a well as severe over the regions. However, cloudburst and the heavy rainfall events occasionally, become difcult to distinguish. The present study attempts to identify the processes associated with cloudburst over elevated orography and compare it with one of the most debated event of 2013 which was reported as heavy rainfall but, not a cloudburst by Indian Meteorological Department (IMD). The temporal variations of rainfall and cloud-top pressure (CTP) are considered to identify the genesis of the event. The vertical developments of the system along with large-scale circulation pattern are estimated in the present study. The result of the study reveals that the mid-tropospheric dry entrainment, low-level temperature inversion and cloud height clearly distinguish the cloudburst and heavy rainfall events and conrms that the system of 2013 was indeed a heavy rainfall event and not a cloudburst.
Keywords Cloudburst Dynamics Scale interaction Monsoon Uttarakhand
Himachal Pradesh
1 Introduction
A cloudburst is characterized by a very heavy rainfall over a small localized area at a very high rainfall rate of order of 100 mm per hour along with strong winds and lightning (Srivastava and Bhardwaj 2014). The affected area does not exceed 2030 square km. The
& S. Chaudhuri [email protected]
1 Department of Atmospheric Science, University of Calcutta, 51/2, Hazra Road, Kolkata 700025,
India
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western Himalayan region experiences the cloudburst during summer monsoon season due to strong monsoon circulation as well as the interaction of monsoon circulation with mid-latitude westerly system. The cloudburst is also likely to occur when monsoon clouds associated with low-pressure area...