Numerical simulation of a super cyclonic storm, Orissa 1999: impact of initial conditions

Trivedi, D.K.; Sanjay, J.; Singh, S. S.

doi:10.1017/s1350482702003109

Cited by 21 publications

(9 citation statements)

References 19 publications

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“…Recently, the MM5 has been used extensively over the Indian region to study a variety of mesoscale phenomena (e.g. Trivedi et al 2002Trivedi et al , 2006Mohanty et al 2004;Rao and Prasad 2005). A version of MM5 is also being used at the National Center for Medium Range Weather Forecasts (NCMRWF), India in realtime for providing numerical forecasting guidance (Das et al 2003).…”

mentioning

confidence: 99%

Assessment of Atmospheric Boundary-Layer Processes Represented in the Numerical Model MM5 for a Clear Sky Day Using LASPEX Observations

Sanjay

2008

Boundary-Layer Meteorol

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Data collected during the Land Surface Processes Experiment (LASPEX) in a semi-arid region of the state of Gujarat in north-west India for a clear sky day (16 May 1997) are used to assess the performance of the atmospheric boundary-layer (ABL) and landsurface parameterizations in the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5). The ABL turbulence parameterizations examined are the Blackadar scheme coupled to a simple soil slab model (SSM), and the Troen-Mahrt scheme coupled to SSM or to the more sophisticated Noah land-surface model (NSM). The comparison of several two-way nested high resolution (9-km) MM5 short term 24-h simulations indicate that, although the model is able to capture the trend in the observed data, the computed results deviate from observations. The NSM with a modest treatment of vegetation outperforms the SSM in capturing the observed daily variations in surface heat fluxes and aspects of ABL structure over the tropical land surface at local scales. Detailed analysis showed that, with the incorporation of observed local vegetation and soil characteristics, the NSM reproduced a realistic surface energy balance and near-surface temperature. It is further found that the coupling of the NSM with the Troen-Mahrt ABL scheme leads to excessive ABL mixing and a dry bias in the model simulations.

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mentioning

confidence: 99%

Assessment of Atmospheric Boundary-Layer Processes Represented in the Numerical Model MM5 for a Clear Sky Day Using LASPEX Observations

Sanjay

2008

Boundary-Layer Meteorol

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“…Also, the simulations with synthetic vortex till 72 h reveal the existence of strong gradients both inside and outside the region of maximum winds. The gradual decrease in wind speed up to the middle and upper troposphere as simulated by Trivedi et al (2002) is with the synthetic vortex after 24 h shows that the wind asymmetries are still present but with maximum wind speeds to the west of the center. The above behavior can be explained from the fact that the tropical cyclone in the run with synthetic vortex shows a south-westward movement from around 13 November 2003 18 UTC.…”

Section: Resultsmentioning

confidence: 76%

“…These figures show the MM5 simulations with and without synthetic vortex. Trivedi et al (2002) included a synthetic vortex in the MM5 for the 1999 Orissa super cyclone and successfully simulated the following typical features of a tropical cyclone, such as asymmetries in the wind field with the strongest winds occurring to the east and close to the cyclone's center. Also their results indicate that strong wind gradients were found between the center and the maximum wind region and there was a slow decrease in wind speed up to the middle troposphere.…”

Section: Resultsmentioning

confidence: 99%

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Impact of modification of initial cyclonic structure on the prediction of a cyclone over the Arabian Sea

2006

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Most tropical cyclones have very few observations in their vicinity. Hence either they go undetected in standard analyses or are analyzed very poorly, with ill defined centres and locations. Such initial errors obviously have major impact on the forecast of cyclone tracks using numerical models. One way of overcoming the above difficulty is to remove the weak initial vortex and replace it with a synthetic vortex (with the correct size, intensity and location) in the initial analysis. The objective of this study is to investigate the impact of introducing NCAR-AFWA synthetic vortex scheme in the regional model MM5 on the simulation of a tropical cyclone formed over the Arabian Sea during November 2003. Two sets of numerical experiments are conducted in this study. While the first set utilizes the NCEP reanalysis as the initial and lateral boundary conditions, the second set utilizes the NCAR-AFWA synthetic vortex scheme. The results of the two sets of MM5 simulations are compared with one another as well as with the observations and the NCEP reanalysis. It is found that inclusion of the synthetic vortex has resulted in improvements in the simulation of wind asymmetries, warm temperature anomalies, stronger vertical velocity fields and consequently in the overall structure of the tropical cyclone. The time series of the minimum sea level pressure and maximum wind speed reveal that the model simulations are closer to observations when synthetic vortex was introduced in the model. The central minimum pressure reduces by 17 hPa while the maximum wind speed associated with the tropical cyclone enhances by 17 m s -1 with the introduction of the synthetic vortex. While the lowest central pressure estimated from the satellite image is 988 hPa, the corresponding value in the synthetic vortex simulated cyclone is 993 hPa. Improvements in the overall structure and initial location of the center of the system have contributed to considerable reduction in the vector track

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“…A collection of research papers on the simulation of the Orissa super-cyclone of 29 October 1999 was published (Mausam 2006, special issue). Earlier, Trivedi et al (2002) and Mohanty et al (2004) had also reported on the simulation of the Orissa cyclone using mesoscale models. The monsoon season of 2005 witnessed an unprecedented heavy rainfall over Mumbai (Santa Cruz) that produced a 94 cm 24 h accumulated rainfall measured at 0300 Coordinated Universal Time (UTC) on 27 July 2005.…”

Section: Introductionmentioning

confidence: 98%

The use and performance of mesoscale models over the Indian region for two high-impact events

Sikka¹,

Rao²

2007

Nat Hazards

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High-impact mesoscale weather events, occurring in different parts of India in all seasons, lead to major weather-and climate-related disasters. Several research groups and operational weather forecasting centres in India have adopted mesoscale models for research and operational usage. This paper reviews the work done by different groups with respect to two specific events, (1) unprecedented locally heavy rainfall near Mumbai (Santa Cruz) on 26 and 27 July 2005 and (2) the Orissa super-cyclone of 29 and 30 October 1999 from its incipient stage on 24 and 25 October 1999. Considerable variability in the prediction of the intensity and location of mesoscale heavy rainfall, as well as in the intensity and path of the super-cyclone, are found. In order to reduce uncertainty in dynamical prediction, it is necessary that the model dynamics, physics, resolution, boundary conditions and availability of data on land-ocean surface processes are tuned separately to the specific event types, such as heavy monsoon rainfall, tropical cyclone genesis and movement and severe local thunderstorms, as the processes controlling such types of events may require suitable treatments for their proper simulations through appropriate dynamics, physics and resolution.

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Numerical simulation of a super cyclonic storm, Orissa 1999: impact of initial conditions

Cited by 21 publications

References 19 publications

Assessment of Atmospheric Boundary-Layer Processes Represented in the Numerical Model MM5 for a Clear Sky Day Using LASPEX Observations

Assessment of Atmospheric Boundary-Layer Processes Represented in the Numerical Model MM5 for a Clear Sky Day Using LASPEX Observations

Impact of modification of initial cyclonic structure on the prediction of a cyclone over the Arabian Sea

The use and performance of mesoscale models over the Indian region for two high-impact events

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