Study of seasonal climatology and interannual variability over India and its subregions using a regional climate model (RegCM3)

Abstract

The temporal and spatial variability of the various meteorological parameters over India and its different subregions is high. The Indian subcontinent is surrounded by the complex Himalayan topography in north and the vast oceans in the east, west and south. Such distributions have dominant influence over its climate and thus make the study more complex and challenging. In the present study, the climatology and interannual variability of basic meteorological fields over India and its six homogeneous monsoon subregions (as defined by Indian Institute of Tropical Meteorology (IITM) for all the four meteorological seasons) are analysed using the Regional Climate Model Version 3 (RegCM3). A 22year (1980-2001) simulation with RegCM3 is carried out to develop such understanding. The National Centre for Environmental Prediction/National Centre for Atmospheric Research, US (NCEP-NCAR) reanalysis 2 (NNRP2) is used as the initial and lateral boundary conditions. The main seasonal features and their variability are represented in model simulation. The temporal variation of precipitation, i.e., the mean annual cycle, is captured over complete India and its homogenous monsoon subregions. The model captured the contribution of seasonal precipitation to the total annual precipitation over India. The model showed variation in the precipitation contribution for some subregions to the total and seasonal precipitation over India. The correlation coefficient (CC) and difference between the coefficient of variation between model fields and the corresponding observations in percentage (COV) is calculated and compared. In most of the cases, the model could represent the magnitude but not the variability. The model processes are found to be more important than in the corresponding observations defining the variability. The model performs quite well over India in capturing the climatology and the meteorological process. The model shows good skills over the relevant subregions during a season.

Isotopic composition of daily precipitation along southern foothills of the Himalayas: impact of marine and continental sources of atmospheric moisture

“…Western Disturbances are eastward moving synoptic low-pressure systems embedded in the lower to mid-tropospheric 15 westerlies in subtropics and originate from the Mediterranean Sea or mid-West Atlantic Ocean (Dimri et al, 2004;Dimri et al 2015;Maharana and Dimri, 2014;Madhura et al, 2015, Rao andSrinivasan, 1969;Pisharoty and Desai, 1956). At times, secondary system of winds with embedded troughs develop over the Persian Gulf and the Black Sea either directly or as a result of the arrival of low-pressure systems from southwest Arabia (Dimri et al, 2004).…”

Assessment of two versions of regional climate model in simulating the Indian Summer Monsoon over South Asia CORDEX domain

“…Mostly, regional models are tuned and evaluated according to their ability to simulate temperature and precipitation (e.g., Giorgi et al 2012;Pattnayak et al 2013a;Maharana and Dimri 2014;Dash et al 2015) over a specific region. However, the role of other climatological parameters such as radiative and moisture fluxes should also be included in the evaluation procedure of regional models Alexandri et al 2015).…”

Isotopic composition of daily precipitation along the southern foothills of the Himalayas: impact of marine and continental sources of atmospheric moisture

“…Western disturbances are eastward moving synoptic lowpressure systems embedded in the lower to mid-tropospheric westerlies in the subtropics and originate from the Mediterranean Sea or mid-West Atlantic Ocean (Dimri et al, 2004(Dimri et al, , 2015Maharana and Dimri, 2014;Madhura et al, 2015;Rao and Srinivasan, 1969;Pisharoty and Desai, 1956). At times, secondary systems of winds with embedded troughs develop over the Persian Gulf and the Black Sea either directly or as a result of the arrival of low-pressure systems from southwest Arabia (Dimri et al, 2004).…”