scholarly journals Medium range prediction of tropical cyclogenesis of intense vortices over Indian Seas by a Global Spectral Model

MAUSAM ◽  
2021 ◽  
Vol 49 (3) ◽  
pp. 331-344
Author(s):  
AKHILESH GUPTA ◽  
K. J. RAMESH ◽  
U. C. MOHANTY
Keyword(s):  
Weather Forecasting ◽  
Spectral Model ◽  
Tropical Cyclogenesis ◽  
New Delhi ◽  
Atmospheric Conditions ◽  
Global Spectral Model ◽  
Quantitative Estimates ◽  
National Centre ◽  
Medium Range ◽  
Indian Seas

The performance of a Global Spectral Model (T-80) operational at the National Centre for Medium Range Weather Forecasting (NCMRWF), New Delhi in predicting the cyclogenesis of six tropical cyclones over Indian Seas formed during 1995-96 has been evaluated. It has been found that the model has the capability to predict cyclogenesis in wind field at least 72 hours in advance although the positions of predicted vortices are seen to be displaced from those of analysed ones in some cases. The quantitative estimates of the atmospheric conditions favourable for cyclogenesis also confirm the conclusions drawn from the qualitative analysis of cyclogenesis predictions of the model in terms of appearance of cyclonic circulation. It also follows from this analysis that the predicted circulations at the cyclogenesis stage are in general more intense and stronger as compared to the corresponding analysis in terms of wind and mass fields. On examining the model systematic errors of prediction it is found that the model has a clear bias for predicting more intense vortex during genesis and weakening stages. On the order hand it predicts relatively less intense vortex during intensification process.

scholarly journals Diurnal Variation in Precipitation over India during the Summer Monsoon Season: Observed and Model Predicted

2007 ◽  
Vol 135 (6) ◽  
pp. 2155-2167 ◽  
Author(s):  
B. K. Basu
Keyword(s):  
Diurnal Variation ◽  
Summer Monsoon ◽  
Weather Forecasting ◽  
Monsoon Season ◽  
Summer Monsoon Season ◽  
Global Spectral Model ◽  
Sea Breezes ◽  
Hourly Precipitation ◽  
Medium Range ◽  
Variance Explained

Abstract Satellite-derived hourly precipitation values over India and neighboring areas are examined during the summer monsoon season of 2004 to determine the observed patterns of diurnal variations. These are compared with the patterns found in the forecasts from the global spectral model in operation at the National Centre for Medium Range Weather Forecasting in India. The observed hourly precipitation shows that maximum amounts are recorded over most areas of India during the afternoon hours, coinciding with the maximum in surface temperature. This pattern is modified in areas where local mesoscale events like katabatic winds or land–sea breezes produce strong convergence patterns and associated convection. The model forecasts weaken the mesoscale effects on precipitation and the convection due to ground heating seems to start in the model 2–3 h before the time it is observed by the satellites. The frequency and amount of precipitation increases with the forecast length but the hour of maximum precipitation remains almost the same. Harmonic analysis of the frequency of observed precipitation shows that the diurnal cycle predominates in both magnitude and the amount of variance explained. The semidiurnal cycle is considerably smaller in magnitude and explains significant variance only over a small area. Other cycles of smaller periodicity are unimportant in the diurnal variation of precipitation. A similar result is also obtained for the model forecasts except that the spatial distributions of amplitude and variance explained are different from that obtained from the observed data. The spatial distribution and values remain almost the same with forecast length.

scholarly journals Dynamic downscaling of the ERA-40 data using a mesoscale meteorological model

2011 ◽  
Vol 12 (1) ◽  
pp. 183 ◽  
Author(s):  
A. PAPADOPOULOS ◽  
G. KORRES ◽  
P. KATSAFADOS ◽  
D. BALLAS ◽  
L. PERIVOLIOTIS ◽  
...  
Keyword(s):  
Dynamical Downscaling ◽  
Weather Forecasting ◽  
Quantitative Estimation ◽  
Three Dimensional ◽  
Atmospheric Model ◽  
Hydrological Models ◽  
Atmospheric Conditions ◽  
Meteorological Model ◽  
Medium Range ◽  
Forecasting System

A sophisticated downscaling procedure that was applied to reproduce high resolution historical records of the atmospheric conditions across the Mediterranean region is presented in this paper. This was accomplished by the dynamical downscaling of the European Center for Medium-Range Forecasts ERA-40 reanalyses with the aid of the atmospheric model of the POSEIDON weather forecasting system. The full three dimensional atmospheric fields with 6 hours of temporal resolution and the surface meteorological parameters at hourly intervals were produced for a 10-year period (1995-2004). The meteorological variables are readily available at 10 km resolution and may constitute the atmospheric forcing to drive wave, ocean hydrodynamic and hydrological models, as well as the baseline data for environmental impact assessment studies. A brief overview of the procedure and a quantitative estimation of the benefit of the new dynamical downscaling dataset are presented.

scholarly journals Technical and operational characteristics of GPS radiosounding system in the upper air network of IMD

MAUSAM ◽  
2021 ◽  
Vol 62 (3) ◽  
pp. 403-416
Author(s):  
GAJENDRA KUMAR ◽  
RANJU MADAN ◽  
K.C. SAIKRISHNAN ◽  
S.K. KUNDU ◽  
P.K. JAIN
Keyword(s):  
Global Positioning System ◽  
Weather Forecasting ◽  
Quality Change ◽  
Weather Forecasts ◽  
National Centre ◽  
Operational Characteristics ◽  
Global Positioning ◽  
Medium Range ◽  
Black List

In recent years, the upper air radiosounding system based on Global Positioning System (GPS) is used as an effective method. GPS receiving device in a Radiosonde improves observation accuracy, allowing simplification of ground equipment. To get improved quality of upper air data, ten stations have been upgraded with new upper air systems based on GPS. This paper describes the upper air radiosounding system that adopts the GPS. After the introduction of GPS Radiosonde in the network at 10 places, data quality has improved substantially at these stations, which has been validated by National Centre for Medium Range Weather Forecasting (NCMRWF) and European Centre for Medium-Range Weather Forecasts (ECMWF). In all cases the quality change has been remarkable and as a result black list tag is removed by ECMWF for the Indian GPS stations.

scholarly journals Ship-Mounted Real-Time Surface Observational System on board Indian Vessels for Validation and Refinement of Model Forcing Fields*

2013 ◽  
Vol 30 (3) ◽  
pp. 626-637 ◽  
Author(s):  
R. Harikumar ◽  
T. M. Balakrishnan Nair ◽  
G. S. Bhat ◽  
Shailesh Nayak ◽  
Venkat Shesu Reddem ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Ocean ◽  
Real Time ◽  
Weather Forecasting ◽  
Ocean Model ◽  
Weather Forecasts ◽  
European Centre ◽  
National Centre ◽  
Medium Range ◽  
Weather Stations

Abstract A network of ship-mounted real-time Automatic Weather Stations integrated with Indian geosynchronous satellites [Indian National Satellites (INSATs)] 3A and 3C, named Indian National Centre for Ocean Information Services Real-Time Automatic Weather Stations (I-RAWS), is established. The purpose of I-RAWS is to measure the surface meteorological–ocean parameters and transmit the data in real time in order to validate and refine the forcing parameters (obtained from different meteorological agencies) of the Indian Ocean Forecasting System (INDOFOS). Preliminary validation and intercomparison of analyzed products obtained from the National Centre for Medium Range Weather Forecasting and the European Centre for Medium-Range Weather Forecasts using the data collected from I-RAWS were carried out. This I-RAWS was mounted on board oceanographic research vessel Sagar Nidhi during a cruise across three oceanic regimes, namely, the tropical Indian Ocean, the extratropical Indian Ocean, and the Southern Ocean. The results obtained from such a validation and intercomparison, and its implications with special reference to the usage of atmospheric model data for forcing ocean model, are discussed in detail. It is noticed that the performance of analysis products from both atmospheric models is similar and good; however, European Centre for Medium-Range Weather Forecasts air temperature over the extratropical Indian Ocean and wind speed in the Southern Ocean are marginally better.

scholarly journals District level value-added dynamical-synoptic forecast system for rainfall

MAUSAM ◽  
2021 ◽  
Vol 57 (2) ◽  
pp. 209-220
Author(s):  
B. LAL ◽  
O. P. SINGH ◽  
ONKARI PRASAD ◽  
S. K. ROY BHOWMIK ◽  
S. R. KALSI ◽  
...  
Keyword(s):  
Weather Forecasting ◽  
Value Added ◽  
India Meteorological Department ◽  
Southwest Monsoon ◽  
District Level ◽  
New Delhi ◽  
Weather Forecasts ◽  
Synoptic Weather ◽  
Mm5 Model ◽  
Medium Range

Lkkj & bl ’kks/k&Ik= esa o"kkZ ls lacaf/kr ftyk Lrjh; ekuksa ij vk/kkfjr xfrdh; flukfIVd iwokZuqeku dh Ik)fr vkSj mlds iz;ksxkRed ifj.kkeksa dks izLrqr fd;k x;k gSA blds igys bl rduhd dk mi;ksx o"kZ 2005 dh ekulwu iwoZ dh _rq] nf{k.kh if’peh ekulwu _rq vkSj ekulwu ds Ik’pkr dh _rq ds nkSjku gqbZ ftysokj o"kkZ dk iwokZuqeku yxkus ds fy, fd;k x;k FkkA mDr 2005 ds iwokZuqeku ds fy, Vh-&80],e- ,e- 5] jk"Vªh; e/; vof/k ekSle iwokZuqeku dsUnz ¼,u- lh- ,e- vkj- MCY;w- ,Q-½ ds- bZ- Vh- ,- vkSj Hkkjr ekSle foKku foHkkx esa dk;Z’khy ,e- ,e- 5 xfrdh; fun’kksZa dk lefUor #Ik ls mi;ksx fd;k x;k FkkA iwokZuqeku esa lefUor #Ik ls ;ksxnku nsus okys lHkh fun’kksZa ds ekuksa dk vyx&vyx ewY;kadu djds muls izkIr gq, o"kkZ ds iwokZuqekuksa dk mi;ksx djds xfrdh; iwokZuqeku rS;kj fd;k x;k gSA ifjpkyu y{k.kksa] m/okZ/kj osx] mixzg ls izkIr lwpuk flukfIVd pkVksZa vkSj tyok;q foKku vkfn tSls vU; fun’kksZa dk vkdyu djds xfrdh; iwokZuqekuksa dks eku vk/kkfjr ¼osY;w ,fMM ½ flukfIVd ekSle iwokZuqekuksa esa ifjofrZr fd;k x;k gSA o"kZ 2005 esa fd, x, iwokZuqeku ds vuqHko ls ;g irk pyk gS fd lefUor #Ik ls ;ksxnku nsus okys fun’kksZa ls vyx&vyx izkIr gq, o"kkZ ds iwokZuqekuksa dh fuiq.krk dh rqyuk esa eku&vk/kkfjr ¼osY;w ,fMM ½ xfrdh; flukfIVd iz.kkyh ds 24, 48, 72 ?kaVksa ds ftyk Lrjh; o"kkZ ds iwokZuqeku dgha vf/kd fuiq.krk ls rS;kj fd, tk ldrs gSaA The paper presents the methodology and trial results of the district level value-added dynamical-synoptic forecast for rainfall. The technique was tried for forecasting districtwise rainfall during Pre-monsoon, Southwest Monsoon and Post monsoon seasons of 2005. The constituent dynamical models were T-80, MM5, ETA of the National Centre for Medium Range Weather Forecasting (NCMRWF) and the MM5 model operational at India Meteorological Department, New Delhi. The dynamical predictions were prepared using the rainfall predictions of the constituent models by assigning different weights. The dynamical predictions were converted into value-added synoptic-weather forecasts by taking into account other inputs like circulation features, vertical velocity, satellite information, synoptic charts and climatology etc. The experience during 2005 has shown that the value-added dynamical-synoptic system can produce 24, 48, 72 hours district level rainfall forecast of greater skill than the skills of the constituent models.

scholarly journals Impact of AMDAR observations from Lufthansa aircraft on Global Analysis - Forecast System

MAUSAM ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 213-220
Author(s):  
SURYA K. DUTTA ◽  
MUNMUN DAS GUPTA ◽  
V. S. PRASAD
Keyword(s):  
Weather Forecasting ◽  
Positive Impact ◽  
Global Analysis ◽  
India Meteorological Department ◽  
Forecasting Model ◽  
Forecast System ◽  
National Centre ◽  
Medium Range ◽  
Special Arrangement

     AMDAR observations from Lufthansa and Lufthansa cargo aircrafts in BUFR format (with header IUADOI EGGR and IUAHOI EGRR) were made available to India Meteorological Department (IMD) and in turn to National Centre for Medium Range Weather Forecasting (NCMRWF) under special arrangement for a period of two weeks w.e.f. 14th May 2008. These data have been assimilated at NCMRWF (National Centre for Medium Range Weather Forecasting) model for the period 14th - 31st May, 2008 to assess its impact on NWP. Use of these observations gave some positive impact on NWP systems.

scholarly journals Tropical cyclone simulations over Bangladesh at convection permitting 4.4 km & 1.5 km resolution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hamish Steptoe ◽  
Nicholas Henry Savage ◽  
Saeed Sadri ◽  
Kate Salmon ◽  
Zubair Maalick ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Tropical Cyclones ◽  
Weather Forecasting ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Level Pressure ◽  
Medium Range ◽  
Gust Speed

AbstractHigh resolution simulations at 4.4 km and 1.5 km resolution have been performed for 12 historical tropical cyclones impacting Bangladesh. We use the European Centre for Medium-Range Weather Forecasting 5th generation Re-Analysis (ERA5) to provide a 9-member ensemble of initial and boundary conditions for the regional configuration of the Met Office Unified Model. The simulations are compared to the original ERA5 data and the International Best Track Archive for Climate Stewardship (IBTrACS) tropical cyclone database for wind speed, gust speed and mean sea-level pressure. The 4.4 km simulations show a typical increase in peak gust speed of 41 to 118 knots relative to ERA5, and a deepening of minimum mean sea-level pressure of up to −27 hPa, relative to ERA5 and IBTrACS data. The downscaled simulations compare more favourably with IBTrACS data than the ERA5 data suggesting tropical cyclone hazards in the ERA5 deterministic output may be underestimated. The dataset is freely available from 10.5281/zenodo.3600201.

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