Ocean Sci. Discuss., https://doi.org/10.5194/os-2018-133 Manuscript under review for journal Ocean Sci. Discussion started: 28 January 2019 c Author(s) 2019. CC BY 4.0 License. 1 Eddy-induced Track Reversal and Upper Ocean Physical- 2 Biogeochemical Response of Tropical Cyclone Madi in the 3 Bay of Bengal 4 Riyanka Roy Chowdhury1, S. Prasanna Kumar2, Arun Chakraborty1 5 1Centre for Oceans, Rivers, Atmosphere and Land Sciences, Indian Institute of Technology Kharagpur, 6 Kharagpur721302, West Bengal, India 7 2CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India 8 Correspondence to: S. Prasanna Kumar (
[email protected]) 9 Abstract. The life cycle of the tropical cyclone Madi in the southwestern Bay of Bengal (BoB) during 6th to 12th 10 December 2013 was studied using a suite of ocean and atmospheric data. Madi formed as a depression on 6th 11 December and intensified into a very severe cyclonic storm by 8th December. What was distinct about Madi was 12 its (1) swift weakening from very severe cyclone to a severe cyclone while moving towards north on 9th, (2) 13 abrupt track reversal close to 180-degree in a southwestward direction on 10th, and (3) rapid decay in the open 14 ocean by 12th December while still moving southwestward. Using both in situ and remote sensing data, we show 15 that oceanic cyclonic eddies played a leading role in the ensuing series of events that followed its genesis. The 16 sudden weakening of the cyclone before its track reversal was facilitated by an oceanic cyclonic (cold-core) 17 eddy, which reduced the ocean heat content and cooled the upper ocean through upward eddy-pumping of 18 subsurface waters.