Coastal circulation along the central west coast of India during cyclone Phyan: measurements and numerical simulations

Measurements and numerical simulations carried out off Mumbai coast for the period 22 October–22 November 2009 showed significant variations in water level and currents during cyclone Phyan. Changes in the meridional component of the current velocity were found to be highly significant during Phyan. The strong southward flow due to the cyclone resulted in a complete nullification of a flood current and continued the net flow towards south for approximately 18 h. This enhanced the ebb flow by about 0.12 m/s off Worli and 0.16 m/s off Satpati. The shift in the cyclone generated currents towards north resulted in an enhancement of flood current by 0.3 m/s off Worli and 0.2 m/s off Satpati. During the first 7 h of Phyan, a strong current system associated with an anti-cyclonic eddy was formed off Mangalore, which propagated towards north up to Ratnagiri and disappeared while the cyclone entered the land. Water level variations of 0.38 and 0.44 m were observed due to Phyan off Worli and Satpati, respectively. Positive and negative surges, that is, a fall in water level up to −20 cm and a rise up to 20 cm, were observed during Phyan and these were associated with shift in the wind direction.