scholarly journals Reexamining the Indian Summer Monsoon Rainfall–ENSO relationship from its recovery in the 21st century:role of the Indian Ocean basin‐wide SST anomaly

2021 ◽  
Author(s):  
Shiyun Yu ◽  
Lei Fan ◽  
Yu Zhang ◽  
Xiao‐Tong Zheng ◽  
Ziguang Li
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
Ocean Basin ◽  
Summer Monsoon Rainfall ◽  
The Indian Ocean ◽  
Sst Anomaly

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 Indian Ocean Dipole : Assessing its impacts on the Indian Summer Monsoon Rainfall (ISMR) across North East India

MAUSAM ◽  
2021 ◽  
Vol 72 (4) ◽  
pp. 821-834
Author(s):  
PARTHAPRATIM SARKAR ◽  
PRASHANTH JANARDHAN ◽  
PARTHAJIT ROY
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
Summer Monsoon Rainfall ◽  
Moisture Movement ◽  
North East India ◽  
North East ◽  
Wind Circulation ◽  
The Indian Ocean

The Indian Ocean Dipole (IOD), a climatic anomaly, results in sustained sea surface temperature (SST) variations between tropical western and eastern Indian Ocean temperatures. In this study, we studied the variations to inculcate the teleconnections between IOD and Indian summer monsoon rainfall (ISMR) distribution across the country for the period 1960-2020 for all the three phases of ISMR. We analyzed rainfall, SST and low-level wind circulation anomalies for the above mentioned time horizon. Positive IOD events noticeably resulted in increase in summer monsoon rainfall distribution across the country respectively while its negative counterpart led to decrease in rainfall except for the commencement phase of ISMR. The variations in SST, wind circulation and moisture movement processes across the Indian Ocean characterize significant changes in rainfall during the positive and negative phases of IOD especially during the recent decades (1991-2020). The recent time horizon also witnesses enhanced low-level equatorial jets (LEJ) across the equatorial Indian Ocean and the Arabian Sea during the positive IOD events as compared to the prior decades (1960-1990). The effect of moisture convergence zone is also analyzed which results in above rainfall conditions across northeastern and central India. Conversely, negative IOD events were found to subdue any such moisture movement mechanisms. Furthermore, and additional investigation to analyze the effect of IOD on the retreating/withdrawal monsoon across northeast India has been done and it has been observed that a stronger positive IOD is detrimental to the seasonal rainfall (May- September) over North East India (-0.7 one month lag correlation). Furthermore, the DMI index of April-May presented a clear indication of monsoon activity over the area during the withdrawal or retreating phase of the summer monsoon, i.e., during September.

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