scholarly journals Relationship between tropospheric thickness anomalies and Indian summer monsoon rainfall

MAUSAM ◽  
2021 ◽  
Vol 47 (4) ◽  
pp. 377-382
Author(s):  
DHANNA SINGH ◽  
C.V.V. BHADRAM ◽  
G.S. MANDAL
Keyword(s):  
Multiple Regression ◽  
Long Range ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Indian Summer Monsoon Rainfall ◽  
Summer Monsoon Rainfall ◽  
Indian Monsoon Rainfall ◽  
Linear Correlations

ABSTRACT .The tropospheric mean monthly thickness anomalies of northern Indian stations of selected layers for the months April to July for a 28 years (1968-95) period have been analysed. The thickness anomalies of April and May exhibit significant persistence through July. Also the thickness anomalies of different layers for the months May-July are found to have generally significant (5% to 0.1% level) linear correlations with the succeeding all India seasonal monsoon rainfall. Out of different layers and all the months analysed, the thickness anomalies of 850-300 and 850-100 hPa layers for May are found to have maximum correlations (significant at 0.1% level). From linear and multiple regression results, 850-300 hPa thickness anomaly is seen to be a useful predictor for long range prediction of Indian monsoon rainfall.  

scholarly journals The Role of the Western Arabian Sea Upwelling in Indian Monsoon Rainfall Variability

2008 ◽  
Vol 21 (21) ◽  
pp. 5603-5623 ◽  
Author(s):  
Takeshi Izumo ◽  
Clémentde Boyer Montégut ◽  
Jing-Jia Luo ◽  
Swadhin K. Behera ◽  
Sébastien Masson ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Indian Summer Monsoon Rainfall ◽  
Summer Monsoon Rainfall ◽  
Indian Monsoon Rainfall ◽  
Precipitation Anomalies

Abstract The Indian summer monsoon rainfall has complex, regionally heterogeneous, interannual variations with huge socioeconomic impacts, but the underlying mechanisms remain uncertain. The upwelling along the Somalia and Oman coasts starts in late spring, peaks during the summer monsoon, and strongly cools the sea surface temperature (SST) in the western Arabian Sea. They restrict the westward extent of the Indian Ocean warm pool, which is the main moisture source for the monsoon rainfall. Thus, variations of the Somalia–Oman upwelling can have significant impacts on the moisture transport toward India. Here the authors use both observations and an advanced coupled atmosphere–ocean general circulation model to show that a decrease in upwelling strengthens monsoon rainfall along the west coast of India by increasing the SST along the Somalia–Oman coasts, and thus local evaporation and water vapor transport toward the Indian Western Ghats (mountains). Further observational analysis reveals that such decreases in upwelling are caused by anomalously weak southwesterly winds in late spring over the Arabian Sea that are due to warm SST/increased precipitation anomalies over the Seychelles–Chagos thermocline ridge of the southwestern Indian Ocean (and vice versa for years with strong upwelling/weak west Indian summer monsoon rainfall). The latter SST/precipitation anomalies are often related to El Niño conditions and the strength of the Indonesian–Australian monsoon during the previous winter. This sheds new light on the ability to forecast the poorly predicted Indian monsoon rainfall on a regional scale, helped by a proper ocean observing/forecasting system in the western tropical Indian Ocean.

scholarly journals Relationship between lower stratospheric circulation and Indian summer monsoon rainfall : Implication for long range forecasts

MAUSAM ◽  
2021 ◽  
Vol 59 (2) ◽  
pp. 173-184
Author(s):  
ANIL KUMAR ROHILLA ◽  
D. S. PAI ◽  
M. RAJEEVAN
Keyword(s):  
Long Range ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
Multiple Linear Regression Model ◽  
Summer Monsoon Rainfall ◽  
Prediction Scheme ◽  
Good Potential ◽  
Stratospheric Circulation

In this study teleconnections between monthly northern hemisphere lower stratospheric geopotential heights (100, 50, 30 hPa) and seasonal Indian Summer Monsoon Rainfall (ISMR) have been established through the correlation analysis. Stable and consistent precursory signals for the ensuing monsoon were identified from the significant teleconnections. The usefulness of the precursory signals for the prediction of ISMR was also tested using a simple multiple linear regression model. These precursory signals show a good potential in the long range prediction scheme of Indian Summer Monsoon Rainfall.

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