National Centre for Medium Range Weather Forecasting

About: National Centre for Medium Range Weather Forecasting is a government organization based out in Noida, India. It is known for research contribution in the topics: Monsoon & Weather Research and Forecasting Model. The organization has 176 authors who have published 368 publications receiving 4749 citations.

Response of tropical cyclone Phailin (2013) in the Bay of Bengal to climate perturbations

Abstract: Tropical cyclones in the Bay of Bengal (BoB) are the major source of loss of properties and lives in the adjacent coastal regions during post-monsoon (October–November) season. This study explores the impact of large-scale environmental change on tropical cyclone (TC) Phailin (2013) in the Bay of Bengal. An ensemble simulation with a regional atmospheric model using different physics and initial conditions is able to capture the observed track of Phailin. The cyclone intensity, however, is underestimated due to the coarse resolution (10 km) of the model. To explore Phailin’s response to a warming climate, a global climate model change signal is added to the cyclone environment using the pseudo-global warming approach, and the ensemble is run again. It is found that changes in the track of Phailin would be small, except around the time of landfall, when Phailin shifts southward in its track. The cyclone becomes more intense and larger, but the translation speed remains nearly unchanged. An analysis of physical processes indicates a deeper TC core due to enhanced latent heating. The vertical distribution of temperature and wind indicates that the eye of Phailin would have a greater vertical extent in the future climate. The expanded size is found to be due to an increase in environmental humidity and temperature in the lower-troposphere leading to an increase in environmental convective available potential energy. The translation speed remains nearly unchanged due to insignificant changes in the steering flow. The result suggests that Phailin, under a warmer climate, may have higher damage potential (~ 22%) compared to the present at the time of landfall.

Past and future trends of hydroclimatic intensity over the Indian monsoon region

Abstract: The hydroclimatic intensity index (HY-INT) is a single index that quantitatively combines measures of precipitation intensity and dry spell length, thus providing an integrated response of the hydrological cycle to global warming. The HY-INT index is a product of the precipitation intensity (PINT, intensity during wet days) and dry spell length (DSL). Using the observed gridded rainfall data sets of 1951–2010 period, the changes in HY-INT, PINT, and DSL over the Indian monsoon region have been examined in addition to changes in maximum consecutive dry days (MCD). We have also considered 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models for examining the changes in these indices during the present-day and future climate change scenarios. For climate change projections, the Representative Concentration Pathway (RCP) 4.5 scenario was considered. The analysis of observational data during the period 1951–2010 suggested an increase in DSL and MCD over most of central India. Further, statistically significant (95% level) increase in HY-INT is also noted during the period of 1951–2010, which is mainly caused due to significant increase in precipitation intensity. The CMIP5 model projections of future climate also suggest a statistically significant increase in HY-INT over the Indian region. Out of the 10 models considered, seven models suggest a consistent increase in HY-INT during the period of 2010–2100 under the RCP4.5 scenario. However, the projected increase in HY-INT is mainly due to increase in the precipitation intensity, while dry spell length (DSL) showed little changes in the future climate.

Role of the Himalayan Orography in Simulation of the Indian Summer Monsoon using RegCM3

Abstract: In this study, sensitivity of the Indian summer monsoon simulation to the Himalayan orography representation in a regional climate model (RegCM) is examined. The prescribed height of the Himalayan orography is less in the RegCM model than the actual height of the Himalayas. Therefore, in order to understand the impact of the Himalayan orography representation on the Indian summer monsoon, the height of the Himalayan orography is increased (decreased) by 10 % from its control height in the RegCM model. Three distinct monsoon years such as deficit (1987), excess (1988) and normal rainfall years are considered for this study. The performance of the RegCM model is tested with the use of a driving force from the reanalysis data and a global model output. IMD gridded rainfall and the reanalysis-2 data are used as verification analysis to validate the model results. The RegCM model has the potential to represent mean rainfall distribution over India as well as the upper air circulation patterns and some of the semi-permanent features during the Indian summer monsoon season. The skill of RegCM is reasonable in representing the variation in circulation and precipitation pattern and intensity during two contrasting rainfall years. The simulated seasonal mean rainfall over many parts of India especially, the foothills of the Himalaya, west coast of India and over the north east India along with the whole of India are more when the orography height is increased. The low level southwesterly wind including the Somali jet stream as well as upper air circulation associated with the tropical easterly jet stream become stronger with the enhancement of the Himalayan orography. Statistical analysis suggests that the distribution and intensity of rainfall is represented better with the increased orography of RegCM by 10 % from its control height. Thus, representation of the Himalayan orography in the model is close to actual and may enhance the skill in seasonal scale simulation of the Indian summer monsoon.

Influence of North Atlantic Oscillation on Indian Summer Monsoon Rainfall in Relation to Quasi-Binneal Oscillation

Abstract: The aim of the present study is to find out the possible linkage between the North Atlantic Oscillation (NAO), a major ocean–atmosphere coupled phenomena believed to be responsible for the variability of Indian Summer Monsoon Rainfall (ISMR) and its relation with Quasi-Biennial Oscillation (QBO) using 60 years (1953–2012) period. Spring North Atlantic Oscillation Index (NAOI) has been found to be inversely correlated with the ISMR, which has been highly enhanced during the east years when the NAOI data have been stratified according to the phases of QBO. The effect of NAOI on the ISMR is shown to be strengthening significant in the later years of the study as compared to that of the initial years of the study. This interesting result provides an input to use it as a predictor of the ISMR.

Improvements in medium range weather forecasting system of India

Abstract: Medium range weather forecasts are being generated in real time using Global Data Assimilation Forecasting System (GDAFS) at NCMRWF since 1994. The system has been continuously upgraded in terms of data usage, assimilation and forecasting system. Recently this system was upgraded to a horizontal resolution of T574 (about 22 km) with 64 levels in vertical. The assimilation scheme of this upgraded system is based on the latest Grid Statistical Interpolation (GSI) scheme and it has the provision to use most of available meteorological and oceanographic satellite datasets besides conventional meteorological observations. The new system has an improved procedure for relocating tropical cyclone to its observed position with the correct intensity. All these modifications have resulted in improvement of skill of medium range forecasts by about 1 day.