Atmospheric physics

1. Sensitivity of physical parameterizations on prediction of tropical cyclone Nargis over the Bay
of Bengal using WRF model.
PREPARE BY : Surendra Singh
Course : M.sc(AP)
Semester : 3rd
Amity University Jaipur
Submitted to : Dr. P.V.S. Raju

2. INTRODUCTION
 This paper is prepared by P. V. S. Raju , Jayaraman Potty and U. C.
Mohanty.
 This paper was published in springer- verlag
 Springer Science+Business Media, commonly known as Springer, is a
German multinational publishing company of books, e-books and
peer-reviewed journals in science, humanities, technical and medical
publishing.
 In this paper the sensitivity of the parameterizations for Tropical
cyclones using the WRF modal is observed.

3.  We have used this modal here to predict nargis cyclones. Which hit
the Myanmar coast on 2 May 2008.
 The effectiveness of this modal is good when the cyclone
approaches the coast.
 The distribution and intensity of rainfall are also well simulated by
the model and comparable with the TRMM estimates.
 The main objective of this paper is twofolds. Primarily, to identify a
suitable combination of parameterization schemes of WRF model
for prediction of tropical cyclones in terms of track and intensity.
Secondarily, by using selected combination of physics schemes,
critically evaluate the performance of WRF core with different initial
conditions starting from 28 April 2008 to 01 May 2008.

4. TROPICAL CYCLONE - NARGIS
 A tropical cyclone is a rapidly rotating storm system characterized by
a low-pressure center, a closed low-level atmospheric circulation,
strong winds, and a spiral arrangement of thunderstorms that
produce heavy rain or squalls.
 We know that cyclones are economically and humanly harmful.
 For example, a cyclone named neamann came in the North Indian
Ocean in 1993. Which led to the loss of 5000 people. And due to the
Nargis cyclone in 2008, 1,30,000 people lost their lives.
 Tropical cyclone formation in the North Indian Ocean is between
April and November.

5.  The India Meteorological Department (IMD) categorizes the cyclonic
storms formed over Bay of Bengal and Arabian Sea is as follows:

6.  Tropical cyclone nargis which changed into a severe cyclonic storm on
28 April 2008, was located 13.0⁰ N, 85.5⁰ E.
 When it hit the Myanmar coast, its position was 16.0⁰ N, 94.0⁰ E.
 A number of parameterization schemes have been developed by
various researchers based on different assumptions.
 Here MM5 and WRF modal are used to predict nargis cyclone. The
accuracy of the MM5 is slightly lower than the wrf modal.

7. WRF MODAL (Weather Research and Forecasting )
 The WRF modal developed by National Center for Atmospheric
Research (NCAR) in 1990s.
 Partnership - National Oceanic and Atmospheric
Administration, National Centers for Environmental Prediction,
Forecast Systems Laboratory, Air Force Weather Agency, Naval
Research Laboratory etc.
 The Weather Research and Forecasting (WRF) model is a numerical
weather prediction (NWP) system designed to serve both atmospheric
research and operational forecasting needs. NWP refers to the
simulation and prediction of the atmosphere with a computer model,
and WRF is a set of software for this.

8.  The model serves a wide range of
meteorological applications across
scales ranging from meters to
thousands of kilometers.
 The WRF model is a non-hydrostatic
mesoscale model designed for
simulation and prediction of fine-scale
atmospheric phenomena.

9. Data and experiment
 The initial boundary condition of the Nargis cyclone was first observed.
 After every 6 hours, the data was taken and analyzed.
 We found out about its estimation intensity and position by JTWC.
 A total of 11 experiments are performed with different parameterization
schemes of cumulus convection, Planetary Boundary Layer (PBL) and
microphysics in order to find out the suitable combination of physical
processes

11. RESULT AND examination
 It is difficult to accurately predict the intensity of any cyclone and the
timing of landfall. It is not possible to make geographically accurate
predictions. If there is even a slight error in the prediction made by us,
then it can cause us great harm.
 Cumulus convection parameterization
 the contributions from the cumulus convection to the large scale moisture
and heat are: Cumulus parameterization schemes are designed to
represent the convective fluxes and the associated condensation or
evaporation.

12.  Here the GD scheme of both PBL scheme
fails to predict the landfall time of nargis
cyclone.
 KF convection and YSU boundary layer
schemes shows better skill in order to
predict the track, intensity and time of
landfall as compared with the other
schemes.

13. Structure of the Tropical Cyclone
 The cyclone had weakened to tropical storm strength. While the spiral
structure is still evident, the eye is poorly defined, and clouds fill the
space the between spiral arms—characteristics of a less-powerful
tropical storm. The typhoon lost strength before coming costal on May 2,
but it still carried very powerful winds and heavy rain.
 The variation in height with its potential temperature (ᶿ e) was observed
by various types of convection scheme.
 The KF scheme with the combination of YSU and MYJ show high (ᶿ e)
value and strong vertical mixing upto 500 hPa,

15. Experiments with microphysics schemes
 In this section 5 types of microphysics scheme have been used with the
help of tracking the TC nargis.
 five microphysics parameterization schemes, namely, Kessler, Lin et al.,
Ferrier, WSM6, Thompson scheme.
 YSU–KF–Ferrier schemes shows less track error during the landfall time
as compared with the remaining microphysics schemes.
 The results of 5 microphysics parameterization schemes influence the
cyclone track prediction and the convective scheme contributes to the
intensity of the tropical cyclone.

17. CONCLUSION
 The prediction of tropical cyclone track, intensity and time of landfall is
still a challenging task.
 Improve the various parameterization schemes and initial conditions.
 Improve the satellite technic and other observation.

18. THANK YOU