On the relationship between Indian summer monsoon withdrawal and Indo-Pacific SST anomalies before and after 1976/1977 climate shift

Abstract The biennial variability is a large component of year-to-year variations in the Indian summer monsoon (ISM). Previous studies have shown that El Niño–Southern Oscillation (ENSO) plays an important role in the biennial variability of the ISM. The present study investigates the role of the Indian Ocean in the biennial transition of the ISM when the Pacific ENSO is absent. The influence of the Indian and Pacific Oceans on the biennial transition between the ISM and the Australian summer monsoon (ASM) is also examined. Controlled numerical experiments with a coupled general circulation model (CGCM) are used to address the above two issues. The CGCM captures the in-phase ISM to ASM transition (i.e., a wet ISM followed by a wet ASM or a dry ISM followed by a dry ASM) and the out-of-phase ASM to ISM transition (i.e., a wet ASM followed by a dry ISM or a dry ASM followed by a wet ISM). These transitions are more frequent than the out-of-phase ISM to ASM transition and the in-phase ASM to ISM transition in the coupled model, consistent with observations. The results of controlled coupled model experiments indicate that both the Indian and Pacific Ocean air–sea coupling are important for properly simulating the biennial transition between the ISM and ASM in the CGCM. The biennial transition of the ISM can occur through local air–sea interactions in the north Indian Ocean when the Pacific ENSO is suppressed. The local sea surface temperature (SST) anomalies induce the Indian monsoon transition through low-level moisture convergence. Surface evaporation anomalies, which are largely controlled by surface wind speed changes, play an important role for SST changes. Different from local air–sea interaction mechanisms proposed in previous studies, the atmospheric feedback is not strong enough to reverse the SST anomalies immediately at the end of the monsoon season. Instead, the reversal of the SST anomalies is accomplished in the spring of the following year, which in turn leads to the Indian monsoon transition.

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Relationship between Indian summer monsoon rainfall and sea surface temperature anomalies over equatorial central and eastern Pacific

MAUSAM ◽

10.54302/mausam.v49i2.3623 ◽

2021 ◽

Vol 49 (2) ◽

pp. 229-234

Author(s):

V. THAPLIYAL ◽

M. RAJEEVAN ◽

S. R. PATIL

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Monsoon Rainfall ◽

Indian Summer Monsoon Rainfall ◽

Monsoon Season ◽

Summer Monsoon Rainfall ◽

Sea Surface ◽

Sst Anomalies

Sea surface temperature (SST) variations over the three key regions over equatorial Pacific, viz., Nino (1+2), Nino 3 and Nino 4 and their relationships with Indian summer monsoon rainfall have been examined in this study. On monthly scale, SST anomalies over the three key regions show an oscillatory type of lagged correlations with Indian monsoon rainfall, positive correlations almost one year before the monsoon season (CC's are of the order of 0.3) which gradually change to significant negative correlation peaking in September/October during/after the monsoon season. The variations on seasonal scale also exhibit the same pattern of monthly variations but more smooth in nature. Composites of similar monsoon years show that during deficient (excess) monsoon years SST anomalies over all the three regions have warmer (cooler) trend which starts about 6 months prior to monsoon season. Tendencies of SST anomalies from previous winter (DJF) to summer (MAM) seasons over Nino 3 and Nino 4 regions are better predictors than EI-Nino categories currently being used in IMD's operational LRF model. By using tendency of SST over EI- Nino -4 region, in place of the category of EI-Nino, the 16 parameter operational Power Regression Model of IMD has been modified. The new forecast model shows better reduction in the forecast error.

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Sensitivity of Soil Water in Community Atmosphere Model (CAM3) for Indian Summer Monsoon (ISM)

International Journal of Environment and Climate Change ◽

10.9734/ijecc/2020/v10i1230317 ◽

2020 ◽

pp. 397-410

Author(s):

Sukanta Kumar Das

Keyword(s):

Soil Water ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Soil Conditions ◽

Community Atmosphere Model ◽

Accumulated Rainfall ◽

Dry Soil ◽

Atmosphere Model ◽

The Impact ◽

The Relationship

The study has been attempted to investigate the relationship between the soil-water and the Indian summer monsoon (ISM) rainfall through the simulation of a global climate model named Community Atmosphere Model (CAM3). Two sets of simulation have been done during monsoon season for the years 2009 to 2012 using the pre-monsoon (May) and the previous winter season (December of previous year) state of soil-water as the model initial conditions. The control simulation and four sensitivity cases assuming 25% and 50% dryer and wetter soil-water respectively have been considered for all the aforesaid four years and for both the set of experiments. It has been observed that the impact of upper level soil-water persist for 15 to 20 days of simulation during the summer monsoon; the middle and lower layer soil state persist for a longer period of time due to its slow-varying nature with time. The daily surface temperature shows strong coupling with the upper layer of soil-water. When taken into comparison with the wet soil conditions, the dry soil state in most of the circumstances causes less rainfall. The Pearson correlation coefficient (PCC) and partial correlation technique have been implied to demonstrate the relationship between the daily soil-water columns, subsequent 30-days accumulated rainfall and past 21-days accumulated rainfall. Strong negative correlation has been reported between the soil-water and subsequent 30-days accumulated (All-India Rainfall) AIR for different simulation cases with dry soil conditions; however, the relation weakened and turned positive over some parts of the region for the simulations with wet soil conditions.

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The fidelity of a regional coupled model in capturing the relationship between intraseasonal variability and the onset/demise of the Indian summer monsoon

Climate Dynamics ◽

10.1007/s00382-020-05252-z ◽

2020 ◽

Vol 54 (11-12) ◽

pp. 4693-4710

Author(s):

Nirupam Karmakar ◽

Vasubandhu Misra

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Intraseasonal Variability ◽

Coupled Model ◽

The Relationship ◽

Regional Coupled Model

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Teleconnection of OLR and SST anomalies over Atlantic Ocean with Indian summer monsoon

Geophysical Research Letters ◽

10.1029/2001gl013837 ◽

2002 ◽

Vol 29 (8) ◽

pp. 125-1-125-4 ◽

Cited By ~ 23

Author(s):

A. K. Srivastava ◽

M. Rajeevan ◽

R. Kulkarni

Keyword(s):

Atlantic Ocean ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Sst Anomalies

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The Influence of Tropical Indian Ocean SST on the Indian Summer Monsoon

Journal of Climate ◽

10.1175/jcli4161.1 ◽

2007 ◽

Vol 20 (13) ◽

pp. 3083-3105 ◽

Cited By ~ 49

Author(s):

Annalisa Cherchi ◽

Silvio Gualdi ◽

Swadhin Behera ◽

Jing Jia Luo ◽

Sebastien Masson ◽

...

Keyword(s):

Pacific Ocean ◽

Indian Ocean ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Tropical Indian Ocean ◽

Tropical Pacific Ocean ◽

Sst Variability ◽

The Indian Ocean ◽

Sst Anomalies ◽

The Tropical Pacific

Abstract The Indian summer monsoon (ISM) is one of the main components of the Asian summer monsoon. It is well known that one of the starting mechanisms of a summer monsoon is the thermal contrast between land and ocean and that sea surface temperature (SST) and moisture are crucial factors for its evolution and intensity. The Indian Ocean, therefore, may play a very important role in the generation and evolution of the ISM itself. A coupled general circulation model, implemented with a high-resolution atmospheric component, appears to be able to simulate the Indian summer monsoon in a realistic way. In particular, the features of the simulated ISM variability are similar to the observations. In this study, the relationships between the ISM and tropical Indian Ocean (TIO) SST anomalies are investigated, as well as the ability of the coupled model to capture those connections. The recent discovery of the Indian Ocean dipole mode (IODM) may suggest new perspectives in the relationship between ISM and TIO SST. A new statistical technique, the coupled manifold, is used to investigate the TIO SST variability and its relation with the tropical Pacific Ocean (TPO). The analysis shows that the SST variability in the TIO contains a significant portion that is independent from the TPO variability. The same technique is used to estimate the amount of Indian rainfall variability that can be explained by the tropical Indian Ocean SST. Indian Ocean SST anomalies are separated in a part remotely forced from the tropical Pacific Ocean variability and a part independent from that. The relationships between the two SSTA components and the Indian monsoon variability are then investigated in detail.

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