Study on the Effect of Hydrometeors on the Track and Intensity of Tropical Cyclone using WRF-ARW Model

Abstract

In this research microphysical and cumulus parameterization schemes on Weather Research and Forecasting (WRF-ARW core) model have been used to study the effects of hydrometeors on the prediction of track and intensity of tropical cyclones Mala (2006), Sidr (2007) and Phailin (2013) which formed over the Bay of Bengal and hit Myanmar, Bangladesh and eastern coast of India respectively. The hydrometeors are cloud water, rain water, graupel, snow, ice and water vapor mixing ratio. The initial and boundary conditions are drawn from the global operational analysis and forecast products of National Center for Environmental Prediction (NCEP-GFS) available for the public at 1°×1° resolution. The model was run by using Kessler, Lin et al., WSM 3-class simple ice, Ferrier (New Eta), WSM 6-class graupel and Thomson graupel microphysics (MP) coupling with different cumulus parameterization (CP) schemes. The CP schemes used to simulate the Tropical Cyclone are Kain-Fritsch (KF) and Betts-Miller-Janjic (BMJ). The model domain consists of 8-24°N and 77-96°E and has 12 km horizontal resolution with 28 vertical sigma levels. The model was run for 96 and 72-h using initial data at 0000 UTC of 26 and 27 April 2006 for TC Mala, at 0000 UTC of 8 and 9 October 2013 for TC Phailin and at 0000 UTC of 11 and 12 November 2007 for TC Sidr. In order to examine the effect of hydrometeors on the movement of tropical cyclones space-averaged vertical profiles of water vapor, cloud water, rain water, graupel, snow, ice mixing ratio (g kg-1 ), vorticity and relative humidity have been calculated once every three hours. For the analysis of effects of cloud hydrometeors the model domain has been divided into 5 different regions. The different regions are Dl (22oN-26oN and 87°E-93oE), D2 (18oN-22°N and 81oE-87°E), D3 (14oN- 18°N and 78-84°E), D4 (12oN-22oN and 84cE-94°E) and D5 (17°N-22°N and 94oE-97°E). The tracks and intensity are compared with those provided by the operational centers like JTWC and IMD. The simulated result suggests that the hydrometeors and vorticity have impact on the track of tropical cyclones. The amount of hydrometeors are started to increase 2 to 3 days before in a direction where the tropical cyclone moves. In all combination of MP and CP the area and time average of water vapor mixing ratio (g/kg) provides similar results. Water vapor mixing ratio has not change significantly during the period of movement of tropical cyclones.