Improvement in Track and Intensity Prediction of Indian Seas Tropical Cyclones with Vortex Assimilation - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 216

(GFDL) long wave and short wave radiation schemes are incorporated in the
model. The details of the model configuration used in the present study are
provided in Table 1.

Table 1: Model configuration for the present study

Model NCEP Mesoscale model WRF

Dynamics Non-hydrostatic with 3-D Coriolis force

Map projection Rotated Lat-Lon

Resolution 9 km

No of vertical levels 51

Horizontal grid scheme Arakawa E grid

Time integration scheme Runge-kutta 2 nd and 3 rd order time splitting

technique with ' t = 20 sec.

Lateral boundary condition NCEP/NCAR GFS forecast

Radiation scheme GFDL LW/SW

PBL scheme YSU

Cumulus parameterization scheme Simplified Arakawa Schubert

Microphysics Ferrier

Two sets of numerical experiments i.e. (i) control simulation (CNTL) and
(ii) data assimilation (DA) is carried out with WRF-NMM model. The model
is integrated up to 72 hrs for Aila case and 96 hrs for Gonu case with the
horizontal resolution of 9 km and 51 vertical levels up to a height of 30 km. A
total of eight cases (three different initial condition for Aila starting from 12
UTC 23 May 2009; five different initial conditions for Gonu starting from 00
UTC 02 June 2007) at every 00 and 12 hr are selected for an enhanced
assessment on the vortex initialization technique along with WRF-NMM
modelling system. For case 1 i.e. for the Bay of Bengal cyclone Aila, the model
is integrated with three different initial conditions i.e. 12 UTC 23 May 2009,
00 UTC 24 May 2009 and 12 UTC 24 May 2009. For case 2 i.e. for the Arabian
Sea cyclone Gonu, the model is integrated with five different initial conditions
i.e. 00 UTC 02 June 2007, 12 UTC 02 June 2007, 00 UTC 03 June 2007, 12
UTC 03 June 2007 and 00 UTC 04 June 2007. The initial and lateral boundary
conditions to a limited area model are usually provided from the large scale
analysis and forecasts available at different NWP centres in the world. The
NCEP Global Forecast System (GFS) analyses and forecasts are used to provide
the initial and lateral boundary conditions to the model respectively.
In order to improve the initial analysis fields for the model integration, an
attempt has been made to initialize WRF-NMM model with WRF-VAR system.
Hence, in the second experiment, i.e. in the data assimilation (DA), the impact
of the observational data sets has been investigated by incorporating the
available conventional and non-conventional data sets over Indian region.
Hence, the model is integrated with three different initial conditions for Aila
and five different initial conditions for Gonu, as mentioned above with the
improved initial conditions through WRF-VAR system.