Summer monsoon over northeastern India during the last millennium

Ashok, Karumuri; Soraisam, Bidyabati; Tejavath, Charan Teja; Cubasch, Ulrich

doi:10.1002/joc.7332

Cited by 5 publications

(1 citation statement)

References 47 publications

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“…Thus, an increased (reduced) gradient of land–sea thermal contrast strengthens (weakens) ISMR over the corresponding landmass (Lindzen and Nigam, 1987; Man and Zhou, 2014). The influence of EXFs on the Tibetan High may also cause decadal changes in the intensity of ISMR covering most of India over the LM by modulating the 100‐hPa tropical easterly jet (Ashok et al , 2022).…”

Section: Discussionmentioning

confidence: 99%

Causes of decadal distributions of Indian summer monsoon rainfall during the last 1500 years

Wang

Shi

et al. 2022

J Quaternary Science

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Understanding the distribution of Indian summer monsoon rainfall (ISMR) and the relationships with external forcing factors (EXFs) and internal climate variability (ICV) is crucial for improving the prediction accuracy of ISMR. Here, we explore and quantify the influence of EXFs and ICV on the distribution of ISMR at decadal timescales over the past 1500 years using the Community Earth System Model (CESM). We identified the major ICV and EXF modes of ISMR distributions in simulations from 501 to 1850 ad and 1851 to 2000 ad. The results show that ICV plays a dominant role in decadal ISMR changes during the pre‐industrial and the current periods. Simulations show east–west contrasts over the Indian subcontinent, with a center of rainfall variability in the high‐latitude regions around 28°N. The EXF mode, calculated from the leading mode of the singular value decomposition analysis, exhibits a nearly uniform increase (or decrease) in the distribution of ISMR over the study region. From 501 to 1850 ad, the signals of greenhouse gases (GHGs), and land use and land cover (LULC) in the ISMR at the decadal timescale are weak and difficult to isolate from the ICV. Our numerical analyses show that natural forcing was a dominant contribution (~64.1%) to the forced ISMR distribution. From 1851 to 2000 ad, natural forcing, GHGs and LULC all contributed to the forced ISMR distribution. GHGs represent a key external forcing factor affecting the distribution of ISMR and could explain 22.3% of the total variance. LULC and natural forcing factors contribute 17.5 and 16.4% to the total variance, respectively. Our results contribute to a better understanding of the mechanisms controlling decadal variability of the Indian summer monsoon.

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Section: Discussionmentioning

confidence: 99%

Causes of decadal distributions of Indian summer monsoon rainfall during the last 1500 years

Wang

Shi

et al. 2022

J Quaternary Science

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Proxy Response in Various Climatic Conditions

Mishra

2023

SpringerBriefs in Environmental Science

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Investigating the Atlantic-Indian monsoon teleconnection pathways in PMIP3 last millennium simulations

Dutta,

Sivankutty,

Neena

2023

Clim Dyn

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The Atlantic multidecadal oscillation (AMO) is considered as one of the major drivers of Indian Summer monsoon (ISM) multidecadal variability, but the exact mechanism of teleconnection remains elusive. AMO can impact the ISM dominantly by two pathways -by generating upperlevel circulation and heating responses across Eurasia and via the Pacific through the atmospheric bridge mechanism and associated modulations of Hadley-Walker circulations in the Indo-Pacific. Using the PMIP3 Last millennium (LM) simulations, the current study investigates the AMO-ISM teleconnection in the context of these pathways of interaction. A significant positive correlation is observed between AMO and ISM in five of the eight models. While the models display only limited skill in simulating the upper-level circulation and tropospheric temperature responses involved in the Eurasian pathway, they exhibit better skill in capturing the Pacific SST responses induced by the AMO. Four of the five models capture the AMO modulation of summer North Atlantic Oscillation (SNAO), but major discrepancies are observed in the SNAO downstream responses. CCSM4 and MPI exhibit better skill in simulating the AMO forced upper-level circulation responses across Eurasia, while CSIRO, GISS and MRI-CGCM3 exhibit better skill in simulating the AMO modulation of extra tropical-tropical SST gradient over the Pacific. Reliability of decadal climate predictions of ISM largely depends on the fidelity of current generation global models in simulating the teleconnection mechanisms which modulate the ISM multidecadal variability, and results from the current study helps in highlighting some of the main deficiencies in model simulated teleconnection processes.

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Summer monsoon over northeastern India during the last millennium

Cited by 5 publications

References 47 publications

Causes of decadal distributions of Indian summer monsoon rainfall during the last 1500 years

Causes of decadal distributions of Indian summer monsoon rainfall during the last 1500 years

Proxy Response in Various Climatic Conditions

Investigating the Atlantic-Indian monsoon teleconnection pathways in PMIP3 last millennium simulations

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