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Vertical structure and evolution of monsoon circulation as observed by 205-MHz wind profiler radar

  • Ajil KottayilEmail author
  • Prince Xavier
  • K. Satheesan
  • K. Mohanakumar
  • V. Rakesh
Original Paper
  • 16 Downloads

Abstract

A wind profiler radar at 205 MHz is operational since January 2017, at Cochin (\(10.04^\circ \hbox {N}\); \(76.33^\circ \hbox {E}\)), a region lying in the west coast of Southern Peninsular India, which also is the entry point of the Indian summer monsoon. Using the radar wind profiles obtained during April to September, the detailed vertical structure of wind during the pre-monsoon and monsoon period was studied for the years 2017 and 2018. The gradual transition from pre-monsoon to monsoon season as manifested by the development of monsoon circulations in the lower and upper troposphere is well captured by the radar observations. Parameters which characterize the strength of monsoon circulations have been derived which are shown to be potential predictors for declaring the monsoon onset over Kerala in an objective manner. The monsoon circulation during the year 2018 was studied in detail in the backdrop of extreme heavy rainfall over Kerala. It is observed that there is an anomalous decrease in the core height, but with high core speed in the Low-level Jet stream (LLJ) during 2018 as compared to year 2017. Owing to this unique placement of LLJ, it can be concluded that intense orographic lifting could have played a role in causing heavy rainfall over Kerala in 2018. The transitions in LLJ prior to heavy rainfall over south-west coast are aptly captured by the radar observations which opens up the possibility of predicting heavy rainfall events through continuous monitoring of monsoon circulation using radar.

Notes

Acknowledgements

We sincerely acknowledge and thank the Science and Engineering Research Board (SERB), Department of Science and Technology (DST), Government of India, for providing the grant and for their assistance in the design and conception of the ST-radar facility at CUSAT. K. Mohanakumar would like to acknowledge the University Grants Commission for providing UGC BSR Faculty Fellowship.

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Copyright information

© Springer-Verlag GmbH Austria, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Advanced Centre for Atmospheric Radar ResearchCochin University of Science and TechnologyCochinIndia
  2. 2.Met Office Hadley CentreExeterUK
  3. 3.Department of Atmospheric SciencesCochin University of Science and TechnologyCochinIndia

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