scholarly journals Association between mid-latitude circulation and Indian monsoon rainfall

MAUSAM ◽  
2021 ◽  
Vol 50 (1) ◽  
pp. 37-42
Author(s):  
R. BHATLA ◽  
J. CHATTOPADHYAY
Keyword(s):  
Summer Monsoon ◽  
General Circulation ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Geographical Area ◽  
Zonal Flow ◽  
Summer Monsoon Rainfall ◽  
Indian Monsoon Rainfall ◽  
Northwest India ◽  
Latitudinal Band

The statistical relationship between the summer monsoon rainfall over India and mid-latitude general calculation at the 500 hPa level was investigated for the period 1971-1989. The index used to characterise general circulation feature is the perturbation of the zonal flow (ratio of meridional to zonal index) for the latitudinal band 35°N - 70°N over different geographical area and the hemisphere. It was found that the perturbation of the zonal flow during preceding January over the geographical sector 1 (45°W - 90°E) shows significant relationship with the subsequent Indian summer monsoon rainfall in an inverse manner. Thus, the perturbation of the mid-latitude circulation during preceding January over the geographical sector seems to be a useful predictor of the subsequent Indian monsoon rainfall. Significant simultaneous inverse relationship also exists between perturbation of mid-latitude zonal flow during July to September over Sector 2 (90°E- 160°W) and summer monsoon rainfall over northwest India.

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 Consistent increase in Indian monsoon rainfall and its variability across CMIP-5 models

2013 ◽  
Vol 4 (1) ◽  
pp. 1-24 ◽  
Author(s):  
A. Menon ◽  
A. Levermann ◽  
J. Schewe ◽  
J. Lehmann ◽  
K. Frieler
Keyword(s):  
Global Warming ◽  
Interannual Variability ◽  
Summer Monsoon ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Indian Monsoon Rainfall ◽  
Wide Range ◽  
The Future ◽  
Rcp 8.5 ◽  
Consistent Increase

Abstract. The possibility of an impact of global warming on the Indian monsoon is of critical importance for the large population of this region. Future projections within the Coupled Model Intercomparison Project Phase 3 (CMIP-3) showed a wide range of trends with varying magnitude and sign across models. Here the Indian summer monsoon rainfall is evaluated in 20 CMIP-5 models for the period 1850 to 2100. In the new generation of climate models a consistent increase in seasonal mean rainfall during the summer monsoon periods arises. All models simulate stronger seasonal mean rainfall in the future compared to the historic period under the strongest warming scenario RCP-8.5. Increase in seasonal mean rainfall is the largest for the RCP-8.5 scenario compared to other RCPs. The interannual variability of the Indian monsoon rainfall also shows a consistent positive trend under unabated global warming. Since both the long-term increase in monsoon rainfall as well as the increase in interannual variability in the future is robust across a wide range of models, some confidence can be attributed to these projected trends.

scholarly journals Consistent increase in Indian monsoon rainfall and its variability across CMIP-5 models

2013 ◽  
Vol 4 (2) ◽  
pp. 287-300 ◽  
Author(s):  
A. Menon ◽  
A. Levermann ◽  
J. Schewe ◽  
J. Lehmann ◽  
K. Frieler
Keyword(s):  
Global Warming ◽  
Interannual Variability ◽  
Summer Monsoon ◽  
Monsoon Rainfall ◽  
Indian Monsoon ◽  
Indian Monsoon Rainfall ◽  
Historic Period ◽  
Wide Range ◽  
Rcp 8.5 ◽  
Consistent Increase

Abstract. The possibility of an impact of global warming on the Indian monsoon is of critical importance for the large population of this region. Future projections within the Coupled Model Intercomparison Project Phase 3 (CMIP-3) showed a wide range of trends with varying magnitude and sign across models. Here the Indian summer monsoon rainfall is evaluated in 20 CMIP-5 models for the period 1850 to 2100. In the new generation of climate models, a consistent increase in seasonal mean rainfall during the summer monsoon periods arises. All models simulate stronger seasonal mean rainfall in the future compared to the historic period under the strongest warming scenario RCP-8.5. Increase in seasonal mean rainfall is the largest for the RCP-8.5 scenario compared to other RCPs. Most of the models show a northward shift in monsoon circulation by the end of the 21st century compared to the historic period under the RCP-8.5 scenario. The interannual variability of the Indian monsoon rainfall also shows a consistent positive trend under unabated global warming. Since both the long-term increase in monsoon rainfall as well as the increase in interannual variability in the future is robust across a wide range of models, some confidence can be attributed to these projected trends.

scholarly journals Observed and model simulated inter-annual variability of the Indian monsoon

MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 133-150
Author(s):  
V. KRISHNAMURTHY ◽  
J. SHUKLA
Keyword(s):  
Interannual Variability ◽  
Summer Monsoon ◽  
General Circulation ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
Circulation Model ◽  
Summer Monsoon Rainfall ◽  
Monsoon Circulation ◽  
Global Response ◽  
Tropical Sst Anomalies

The Center for Ocean-Land-Atmosphere (COLA) general circulation model has been integrated seven times with observed global sea surface temperature (SST) for the years 1979-98. The model-simulated annual cycle, the seasonal mean and the interannual variability of the summer monsoon rainfall and circulation over the Indian region are compared with the corresponding observations. It if found that, although this model has shown remarkable success in simulating the local and global response of tropical SST anomalies, the model shows poor skill in simulating the interannual variability of monsoon rainfall over India. While it is true that the correlation between the observed tropical Pacific SST and the Indian summer monsoon rainfall for the most recent 20 years itself is considerably over India is largely related to the systematic errors of the model in simulating the climatological mean monsoon circulation and rainfall, especially over the oceanic regions.

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