Applying the Betts-Miller-Janjic scheme of convection in prediction of the Indian monsoon

The performance of the Betts-Miller-Janjic scheme of convection has been investigated for prediction of the Indian monsoons. For this purpose a limited area numerical weather prediction model with two schemes of convection, one with the Betts-Miller scheme and other with the Betts-Miller-Janjic scheme, is run for five cases of monsoon depression that made landfall over the Indian coast. The results from the two schemes are compared. Detailed analyses of mean sea level pressure, wind, and rainfall have shown that the Betts-Miller-Janjic scheme has considerably improved the rainfall prediction over the Indian landmass and improvement is also seen in the mean sea level pressure fields and cyclonic circulation associated with the depression at the 850-hPa level. The forecast results are further verified by computing the root-mean-square errors, and the difference in the skill scores between the two model runs are tested for their statistical significance. It is found that the Betts-Miller-Janjic scheme has a statistically significant effect on the model skill beyond 24 h, with maximum impact on mean sea level pressure and geopotential height. The performance of the Betts-Miller-Janjic scheme of convection has been investigated for prediction of the Indian monsoons. For this purpose a limited area numerical weather prediction model with two schemes of convection, one with the Betts-Miller scheme and other with the Betts-Miller-Janjic scheme, is run for five cases of monsoon depression that made landfall over the Indian coast. The results from the two schemes are compared. Detailed analyses of mean sea level pressure, wind, and rainfall have shown that the Betts-Miller-Janjic scheme has considerably improved the rainfall prediction over the indian landmass and improvement is also seen in the mean sea level pressure fields and cyclonic circulation associated with the depression at the 850-hPa level. The forecast results are further verified by computing the root-mean-square errors, and the difference in the skill scores between the two model runs are tested for their statistical significance. It is found that the Betts-Miller-Janjic scheme has a statistically significant effect on the model skill beyond 24 h, with maximum impact on mean sea level pressure and geopotential height

Thermodynamic adjustment parameters in the Betts-Miller scheme of convection

The sensitivity of the prediction of a monsoon depression to the adjustment parameters in a Betts-Miller scheme of deep convection is examined and an optimum parameter set is identified for the monsoon depression. For this purpose, a number of experiments have been carried out with a limited area model by assigning different values to the adjustment parameters, namely, the saturation pressure departure, the stability weight, and the adjustment time period. When one parameter is varied, the other two are kept constant. Results indicate that the depression track is sensitive to all three adjustment parameters. The upper-tropospheric temperature is sensitive to the stability weight and the rainfall rates are sensitive to the saturation pressure departure values. The rainfall shows minor sensitivity to the stability weight and the adjustment time period. A set of adjustment parameters that produced the best forecasts is taken as the optimum parameter set for the monsoon depression

Malignant Melanoma of Nose and Paranasal Sinuses: 2 Case Reports

Malignant melanoma is one of the rare and highly aggressive diseases of the sinonasal cavity. High index of suspicion is required for diagnosis as the patient usually presents with non specific signs and symptoms. In the natural course of the disease, higher rate of loco regional recurrences and distant metastasis are seen making the overall prognosis of disease very poor. In reviewing the various treatment modalities used in the past, surgical resection of the tumour with postoperative radiotherapy is preferred one. Advances in surgery, radiotherapy and chemotherapy don’t have any impact on improved survival, which remains poor in this disease. We report two cases of malignant melanoma, which were treated at our institute

Application of semi-implicit scheme of integration to barotropic prediction

Application of a semi-implicit version of primitive equation barotropic model to predict monsoon depressions is proposed. Forecasts upto 48 hr have been quite satisfactory. The results are compared with those obtained from an explicit version of primitive equation barotropic model developed earlier. The flow patterns from these two versions are similar with few exceptions in isolated pockets, however, the forecast movement obtained from the semi-implicit version is comparable or slightly superior to those obtained from the explicit version. The computational time in semi-implicit and explicit schemes is approximately in the ratio of 1:2

Aggressive Fibromatosis in Neck.

Aggressive fibromatosis (AF) is a locally aggressive infiltrative low-grade benign tumor that accounts for approximately less than 3% of all soft tissue tumors. In the head and neck region this tumor tends to be more aggressive and associated with significant morbidity. Aggressive surgery is a viable management option and may be successfully used as a single modality treatment, or in combination with radiotherapy. We report a rare case of AF in a 38 year old female, who presented with a painless mass over the left supraclavicular fossa, extending inferiorly into the thoracic inlet, which was excised successfully in toto with the help of cardiothoracic vascular surgeon (CTVS)

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

Numerical simulations are performed using the Penn State University/ National Center for Atmospheric Research Mesoscale Model (MM5) to study the impact of initial conditions on the super cyclone which hit the coast of Orissa in 1999. Because analysis of the cyclone's circulation was inadequate in the initial fields owing to the coarse resolution of the operational analysis systems and sparse oceanic data coverage, synthetic vortex data were generated using empirical relations and used in the analysis. Four-dimensional data assimilation is performed in order to assimilate the synthetic vortex in the initial stage to the model. Considerable improvement in the track is obtained by using the synthetic vortex. With better specification of the initial vortex structure, the model successfully simulated the typical tropical cyclone characteristics, such as asymmetries in the wind field: the strongest winds occurred in the east and close to the cyclone's centre, strong wind gradients were found between the centre and the maximum wind region, and there was a slow decrease in wind speed up to the middle troposphere. Despite failing to produce the intense pressure drop observed for this cyclone, the model shows much better cyclone development with enhanced initial condition than the analysis

On some aspects of initialization and forecasts in the Indian monsoon region.

Application of a dynamic initialization scheme for balancing initial wind and pressure fields for a one-level primitive equation model in the Indian region has been investigated. For this purpose, the model equations are integrated forward and backward around the initial time following the Euler backward time-difference scheme without restoration of any variable. For comparison, the initial wind-pressure balance has also been constructed from the observed horizontal motion field by a hierarchy of models of increasing complexity, using the geostrophic relation, the linear balance equation and the nonlinear balance equation. Furthermore, the 48 h forecasts are prepared using the balanced initial data derived from the static nonlinear balance equation and the dynamic initialization scheme. The forecast results from both initialization schemes are compared and discussed. The results obtained from the dynamic initialization scheme are found to be either slightly superior or comparable to those based on the static initialization scheme

Harmonic analysis of summer mean wind at 200 mbar level during contrasting monsoon years over India

Summer (June-August) mean zonal and meridional wind components at 200 mbar level are subjected to harmonic analysis for the years 1970, 1971, 1972 and 1979. It is found that the small scale disturbances are intense during normal monsoon years. The westerlies in the belt 10°S to 30°S are stronger during drought years. During normal monsoon years (1970, 1971) the northward transport of westerly momentum by wave number 1 at 19.6°N is large as compared to drought years (1972, 1979). The transport of westerly momentum by standing eddies is northward for all the years between 5°S and 28.7°N but large during the normal monsoon years

Intra-seasonal variations of kinetic energy of lower tropospheric zonal waves during northern summer monsoon

Space spectral analysis of zonal (u) and meridional (v) components of wind and time spectral analysis of kinetic energy of zonal waves at 850 hPa during monsoon 1991 (1st June 1991 to 31st August 1991) for the global belt between equator and 40°N are investigated. Space spectral analysis shows that long waves (wavenumbers 1 and 2) dominate the energetics of Region 1 (equator to 20°N) while over Region 2 (20°N to 40°N) the kinetic energy of short waves (wavenumbers 3 to 10) is more than kinetic energy of long waves. It has been found that kinetic energy of long waves is dominated by zonal component while both (zonal and meridional) the components of wind have almost equal contribution in the kinetic energy of short waves. Temporal variations of kinetic energy of wavenumber 2 over Region 1 and Region 2 are almost identical. The correlation matrix of different time series shows that (i) wavenumber 2 over Regions 1 and 2 might have the same energy source and (ii) there is a possibility of an exchange of kinetic energy between wavenumber 1 over Region 1 and short waves over Region 2. Wave to wave interactions indicate that short waves over Region 2 are the common source of kinetic energy to wavenumber 2 over Regions 1 and 2 and wavenumber 1 over Region 1. Time spectral analysis of kinetic energy of zonal waves indicates that wavenumber 1 is dominated by 30-45 day and bi-weekly oscillations while short waves are dominated by weekly and bi-weekly oscillations. The correlation matrix, wave to wave interaction and time spectral analysis together suggest that short period oscillations of kinetic energy of wavenumber 1 might be one of the factors causing dominant weekly (5-9 day) and bi-weekly (10-18 day) oscillations in the kinetic energy of short waves

Impact of modified physics in limited area model forecasts

A number of physical factors have been introduced to improve limited area model forecasts. The factors include land surface fluxes, shallow convection and radiation. The model including these additional physical factors (modified physics) is run for five cases of monsoon depression which made landfall over the Indian coast, and the results are compared with those of the control run. The forecasts are verified by computing the root mean square and mean errors. The differences in these skill scores between the two model runs are tested for their statistical significance. It is found that the modified physics has a statistically significant effect on the model skill with the maximum impact on the mean sea level pressure and the temperature. Detailed analyses of mean sea level pressure, wind, rainfall and temperature further confirm that the modified physics has maximum impact on mean sea level pressure and temperature and marginal impact on wind and rainfall. Furthermore, analyses of some model parameters related to physics at a grid point for one case of depression were done. The results show that the inclusion of the land surface physics, shallow convection and radiative processes have produced a better precipitation forecast over the grid point