Simulation of Cyclone ‘Aila-2009’ by Using WRF-ARW Model and Numerical Storm Surge Model - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 259

phenomena ranging from metres to thousands of kilometres. Advance Research
WRF (ARW) is a dynamic solver (Skamarock, 2005), which is compatible
with the WRF system to simulate broad spectrum of meteorological phenomena.
WRF-ARW Model integrates the compressible, non-hydrostatics Euler
equations, which are cast in flux form (Ooyama, 1990) with terrain-following
mass vertical coordinates (Laprise, 1992).
2.1.1 Experimental Setup
The Model was run at 9 km horizontal resolution with 27 vertical terrain
following eta levels in order to simulate the cyclone Aila-2009. Kain-Fritch
cumulus parameterization scheme and WRF-Single Moment 3-class (WSM 3-
class scheme), Hong, Dudhia and Chen (2004) micro-physics (simple ice and
snow scheme) were used for simulating the events. Surface layer was treated
using Monin-Obukhov with Carslon-Bolan viscous sub-layer option and
boundary layer was treated with Yonsei University scheme. Noah 4-layer Land
Surface Model (LSM) was utilized with the above combination. Long and
short wave radiations were treated with Rapid Radiative Transfer Model
(RRTM) and Dudhia schemes, respectively. Time step of integration was set to
50 seconds for maintaining the computational stability (so called CFL
condition). The model uses 3 rd order Runge-Kutta time integration scheme.
2.1.2 Simulation of Pressure, Wind and Rainfall Associated with
Cyclone Aila-2009 by using WRF-ARW Model
WRF-ARW model is utilized to simulate movement and structure of the above
tropical cyclone. National Center for Environment Prediction (NCEP) Final
Analysis (FNL) data is utilized as initial and lateral boundary conditions (LBCs)
at six hourly intervals. WRF-ARW model was run for 48 hrs to simulate track
and structure of the tropical cyclone Aila (2009) formed in the Bay of Bengal.
The model is initialized at 0000 UTC (24 May 2009). Maximum sustained
wind, central pressure and position of the tropical cyclone were extracted from
the simulated outputs. Analysis domain was 02-27°N, 73-104°E to well capture
the scenarios of the cyclone Aila. Maximum sustained wind, central sea level
pressure, 24 hours rainfall, and track positions associated with the cyclones
are calculated and investigated for understanding behaviour of the systems.
Grid Analysis and Display System ( GrADS ) software is used for visualization.
2.2 Numerical/Hydro-dynamical Storm Surge Model
with Air Bubble Entrainment
The numerical/hydro-dynamical storm surge model with air bubble entrainment
is developed at the SAARC Meteorological Research Centre (SMRC), Dhaka
by S.K. Debsarma in 2009 based on the Indian Institute of Technology Delhi
(IITD) Model. The basic hydrodynamic equations of continuity and momentum
were integrated vertically. Air-Bubble Entrainment is made by introducing