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.

Impact of Coupling with an Ice–Ocean Model on Global Medium-Range NWP Forecast Skill

2018 ◽  
Vol 146 (4) ◽  
pp. 1157-1180 ◽  
Author(s):  
Gregory C. Smith ◽  
Jean-Marc Bélanger ◽  
François Roy ◽  
Pierre Pellerin ◽  
Hal Ritchie ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Large Scale ◽  
Weather Forecasting ◽  
Positive Impact ◽  
Weather Prediction ◽  
Ocean Model ◽  
Forecast Skill ◽  
Medium Range ◽  
Forecasting System ◽  
The Impact

The importance of coupling between the atmosphere and the ocean for forecasting on time scales of hours to weeks has been demonstrated for a range of physical processes. Here, the authors evaluate the impact of an interactive air–sea coupling between an operational global deterministic medium-range weather forecasting system and an ice–ocean forecasting system. This system was developed in the context of an experimental forecasting system that is now running operationally at the Canadian Centre for Meteorological and Environmental Prediction. The authors show that the most significant impact is found to be associated with a decreased cyclone intensification, with a reduction in the tropical cyclone false alarm ratio. This results in a 15% decrease in standard deviation errors in geopotential height fields for 120-h forecasts in areas of active cyclone development, with commensurate benefits for wind, temperature, and humidity fields. Whereas impacts on surface fields are found locally in the vicinity of cyclone activity, large-scale improvements in the mid-to-upper troposphere are found with positive global implications for forecast skill. Moreover, coupling is found to produce fairly constant reductions in standard deviation error growth for forecast days 1–7 of about 5% over the northern extratropics in July and August and 15% over the tropics in January and February. To the authors’ knowledge, this is the first time a statistically significant positive impact of coupling has been shown in an operational global medium-range deterministic numerical weather prediction framework.

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.

Impact of the Different Components of 4DVAR on the Global Forecast System of the Meteorological Service of Canada

2007 ◽  
Vol 135 (6) ◽  
pp. 2355-2364 ◽  
Author(s):  
Stéphane Laroche ◽  
Pierre Gauthier ◽  
Monique Tanguay ◽  
Simon Pellerin ◽  
Josée Morneau
Keyword(s):  
Data Assimilation ◽  
Positive Impact ◽  
Weather Forecast ◽  
Forecast Model ◽  
Variational Data Assimilation ◽  
Global Forecast System ◽  
Forecast System ◽  
Medium Range Weather Forecast ◽  
Medium Range ◽  
The Impact

Abstract A four-dimensional variational data assimilation (4DVAR) scheme has recently been implemented in the medium-range weather forecast system of the Meteorological Service of Canada (MSC). The new scheme is now composed of several additional and improved features as compared with the three-dimensional variational data assimilation (3DVAR): the first guess at the appropriate time from the full-resolution model trajectory is used to calculate the misfit to the observations; the tangent linear of the forecast model and its adjoint are employed to propagate the analysis increment and the gradient of the cost function over the 6-h assimilation window; a comprehensive set of simplified physical parameterizations is used during the final minimization process; and the number of frequently reported data, in particular satellite data, has substantially increased. The impact of these 4DVAR components on the forecast skill is reported in this article. This is achieved by comparing data assimilation configurations that range in complexity from the former 3DVAR with the implemented 4DVAR over a 1-month period. It is shown that the implementation of the tangent-linear model and its adjoint as well as the increased number of observations are the two features of the new 4DVAR that contribute the most to the forecast improvement. All the other components provide marginal though positive impact. 4DVAR does not improve the medium-range forecast of tropical storms in general and tends to amplify the existing, too early extratropical transition often observed in the MSC global forecast system with 3DVAR. It is shown that this recurrent problem is, however, more sensitive to the forecast model than the data assimilation scheme employed in this system. Finally, the impact of using a shorter cutoff time for the reception of observations, as the one used in the operational context for the 0000 and 1200 UTC forecasts, is more detrimental with 4DVAR. This result indicates that 4DVAR is more sensitive to observations at the end of the assimilation window than 3DVAR.

Unravelling the mechanism of extreme (more than 30 sigma) precipitation during August 2018 and 2019 over Kerala, India

2021 ◽  
Author(s):  
Parthasarathi Mukhopadhyay ◽  
Peter Bechtold ◽  
Yuejian Zhu ◽  
R. Phani Murali Krishna ◽  
Siddharth Kumar ◽  
...  
Keyword(s):  
Large Scale ◽  
Moisture Convergence ◽  
Mountain Range ◽  
Shallow Convection ◽  
Forecast System ◽  
Medium Range Weather Forecast ◽  
National Centre ◽  
Medium Range ◽  
Rainfall Anomalies ◽  
Rain Events

AbstractDuring August 2018 and 2019 the southern state of India, Kerala received unprecedented heavy rainfall which led to widespread flooding. We aim to characterize the convective nature of these events and the large-scale atmospheric forcing, while exploring their predictability by three state of the art global prediction systems, the National Centre for Environmental Prediction (NCEP) based India Meteorological Department (IMD) operational Global Forecast System (GFS), the European Centre for Medium Range Weather Forecast (ECMWF) integrated forecast system (IFS) and the Unified Model based NCUM being run at the National Centre for Medium Range Weather Forecasting (NCMRWF).Satellite, radar and lightning observations suggest that these rain events were dominated by cumulus congestus and shallow convection with strong zonal flow leading to orographically enhanced rainfall over the Ghats mountain range, sporadic deep convection was also present during the 2019 event. A moisture budget analyses using the ERA5 (ECMWF Reanalyses version 5) reanalyses and forecast output revealed significantly increased moisture convergence below 800 hPa during the main rain events compared to August climatology. The total column integrated precipitable water tendency, however is found to be small throughout the month of August, indicating a balance between moisture convergence and drying by precipitation. By applying a Rossby wave filter to the rainfall anomalies it is shown that the large-scale moisture convergence is associated with westward propagating barotropic Rossby waves over Kerala, leading to increased predictability of these events, especially for 2019.Evaluation of the deterministic and ensemble rainfall predictions revealed systematic rainfall differences over the Ghats mountains and the coastline. The ensemble predictions were more skilful than the deterministic forecasts, as they were able to predict rainfall anomalies (>3 standard deviations from climatology) beyond day 5 for August 2019 and up to day 3 for 2018.

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 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.

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