Holocene climate variability and Indian Summer Monsoon: An overview

The Holocene ◽  
2020 ◽  
Vol 30 (5) ◽  
pp. 744-773 ◽  
Author(s):  
Upasana S Banerji ◽  
P Arulbalaji ◽  
D Padmalal
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
Ice Age ◽  
Interglacial Period ◽  
Northern Indian Ocean ◽  
The Holocene ◽  
Indian Landmass ◽  
Holocene Period

The response of the Indian Summer Monsoon (ISM) to forcing factors and climate variables has not yet fully explored, even though the ISM plays a pivotal role in the socio-economics of the Indian subcontinent and nearby areas. The ISM progression over Indian landmass is a manifestation of the Intertropical Convergence Zone (ITCZ) migration over the northern Indian Ocean and the Indian subcontinent. The recent anomalous behaviour of ISM raises the need for a better understanding of its spatio-temporal changes during the ongoing interglacial period termed as the Holocene period. The Holocene period has been classified further based on the globally observed abrupt climatic events at 8.2 and 4.2 ka. The 8.2 ka global cooling events have been recorded from northern Indian Ocean marine archives but limited records from the continental archives of the Indian landmass has demonstrated the 8.2 ka event. At the same time, the 4.2 ka dry climate has been endorsed by both marine as well as continental records and agrees with the global studies. During the ‘Little Ice Age’ (LIA), in the India subcontinent, wet conditions prevailed in the northern, central and western regions while a dry climate existed over the greater part of peninsular India. The present review offers an account of ISM signatures and possible mechanisms associated with the monsoon variability in the Indian subcontinent and the northern Indian Ocean during the Holocene period.

scholarly journals Impact of Indian Summer Monsoon Change on Ancient Indian Civilizations During the Holocene

2021 ◽  
Vol 9 ◽  
Author(s):  
Amzad Hussain Laskar ◽  
Archna Bohra
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Global Climate ◽  
Interglacial Period ◽  
Human Settlement ◽  
Indus Civilization ◽  
The Holocene ◽  
Climate Event ◽  
Ancient Civilizations

A large part of South Asia receives rainfall mainly during the Indian Summer Monsoon (ISM) season of the year (Jun–Sep). The socioeconomic conditions of most of the developing countries in this region largely depend on the ISM rains. It also played important roles in rise and collapse of ancient civilizations in this region. However, the influence of the ISM on Indian ancient civilizations has not yet been fully explored though there were some attempts to correlate monsoon variation with their rise and fall. For example, in the mid to late Holocene period, Indus Valley or Harappan Civilization flourished in the western part of India from its early development, through its urbanization and eventual transformation into a rural society. Probably a prolonged decrease in the ISM rainfall caused the decline in the urban phase of the Indus Civilization around the 4.2 kyr BP global climate event. Another well-recorded early Holocene global climate event is the 8.2 kyr BP cooling event which also reportedly influenced ISM significantly, but its impact on human settlement is not clear in this region. The present study is a comprehensive review of the archaeological and climatological researches carried out on the role of ISM variability on the rise and fall of ancient Indian civilizations for the most part of the ongoing interglacial period, the Holocene. The review covers the studies on the period of the last 10 kyr as evidence suggests that human settlement and cultural developments in this region started around the beginning of this period. We have noted that the existing studies are mostly restricted to vague qualitative analysis of the weakening/strengthening of the ISM, and researches related to quantitative estimations of changes of the monsoon strengths and durations of drought events that caused collapse of civilizations are limited. Therefore, in the present analysis, emphasis has also been given on the requirement of estimating the absolute changes that might have caused cultural shifts. Some possible ways to quantitatively estimate the changes of some climate parameters are discussed.

scholarly journals Indian Ocean and Indian summer monsoon: relationships without ENSO in ocean–atmosphere coupled simulations

2016 ◽  
Vol 49 (4) ◽  
pp. 1429-1448 ◽  
Author(s):  
Julien Crétat ◽  
Pascal Terray ◽  
Sébastien Masson ◽  
K. P. Sooraj ◽  
Mathew Koll Roxy
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Ocean Atmosphere

scholarly journals A Central Indian Ocean Mode and Heavy Precipitation during the Indian Summer Monsoon

2017 ◽  
Vol 30 (6) ◽  
pp. 2055-2067 ◽  
Author(s):  
Lei Zhou ◽  
Raghu Murtugudde ◽  
Dake Chen ◽  
Youmin Tang
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Critical Role ◽  
Western Indian Ocean ◽  
Heavy Precipitation ◽  
Central Indian Ocean ◽  
Monsoonal Precipitation ◽  
Monsoon System ◽  
The Indian Ocean

A central Indian Ocean (CIO) mode is found to play a critical role in driving the heavy precipitation during the Indian summer monsoon (ISM). It is typically denoted with a combination of intraseasonal sea surface temperature (SST) anomalies and intraseasonal wind anomalies over the central Indian Ocean, and it preserves the mechanistic links among various dynamic and thermodynamic fields. Like a T junction, it controls the propagation direction of the intraseasonal variabilities (ISVs) originating in the western Indian Ocean. During the ISM, the CIO mode creates an environment favorable for the northward-propagating mesoscale variabilities. These results unveil the relation between the subseasonal monsoonal precipitation and the CIO mode in the ocean–atmosphere system in the Indian Ocean. The identification of the CIO mode deepens our understanding of the coupled monsoon system and brightens the prospects for better simulation and prediction of monsoonal precipitation in the affected countries.

scholarly journals The ENSO teleconnections to the Indian summer monsoon climate through the Last Millennium as simulated by the PMIP3

2018 ◽  
Author(s):  
Charan Teja Tejavath ◽  
Karumuri Ashok ◽  
Supriyo Chakraborty ◽  
Rengaswamy Ramesh
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Little Ice Age ◽  
Walker Circulation ◽  
Summer Monsoon Rainfall ◽  
Ice Age ◽  
Boreal Summer ◽  
Last Millennium ◽  
Enso Teleconnections ◽  
The Mean

Abstract. Using seven model simulations from the PMIP3, we study the mean summer (June–September) climate and its variability in India during the Last Millennium (LM; CE 850–1849) with emphasis on the Medieval Warm Period (MWP) and Little Ice Age (LIA), after validation of the simulated current day climate and trends. We find that the above (below) LM-mean summer global temperatures during the MWP (LIA) are associated with relatively higher (lower) number of concurrent El Niños as compared to La Niñas. The models simulate higher (lower) Indian summer monsoon rainfall (ISMR) during the MWP (LIA). This is notwithstanding a strong simulated negative correlation between the timeseries of NINO3.4 index and that of the area-averaged ISMR, Interestingly, the percentage of strong El Niños (La Niñas) causing negative (positive) ISMR anomalies is higher in the LIA (MWP), a non-linearity that apparently is important for causing higher ISMR in the MWP. Distribution of simulated boreal summer velocity potential at 850 hPa during MWP in models, in general, shows a zone of anomalous convergence in the central tropical Pacific flanked by two zones of divergence, suggesting a westward shift in the Walker circulation as compared to the simulations for LM as well as and a majority of historical simulations, and current day observed signal. The anomalous divergence centre in the west also extends into the equatorial eastern Indian Ocean, resulting in an anomalous convergence zone over India and therefore excess rainfall during the MWP as compared to the LM; the results are qualitative, given the inter-model spread.

scholarly journals Meridionally Extending Anomalous Wave Train over Asia During Breaks in the Indian Summer Monsoon

2019 ◽  
Vol 3 (3) ◽  
pp. 353-366 ◽  
Author(s):  
Uppara Umakanth ◽  
Ramesh K. Vellore ◽  
R. Krishnan ◽  
Ayantika Dey Choudhury ◽  
Jagat S. H. Bisht ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
General Circulation ◽  
Wave Train ◽  
Eastern China ◽  
Circulation Model ◽  
Cyclonic Circulation ◽  
The Arctic ◽  
Indian Landmass ◽  
Central Eastern

Abstract Anomalous interactions between the Indian summer monsoon (ISM) circulation and subtropical westerlies are known to trigger breaks in the ISM on subseasonal time-scales, characterised by a pattern of suppressed rainfall over central-north India, and enhanced rainfall over the foothills of the central–eastern Himalayas (CEH). An intriguing feature during ISM breaks is the formation of a mid-tropospheric cyclonic circulation anomaly extending over the subtropical and mid-latitude areas of the Asian continent. This study investigates the mechanism of the aforesaid Asian continental mid-tropospheric cyclonic circulation (ACMCC) anomaly using observations and simplified model experiments. The results of our study indicate that the ACMCC during ISM breaks is part of a larger meridional wave train comprising of alternating anticyclonic and cyclonic anomalies that extend poleward from the monsoon region to the Arctic. A lead–lag analysis of mid-tropospheric circulation anomalies suggests that the meridional wave-train generation is linked to latent heating (LH) anomalies over the CEH foothills, Indo-China, and the Indian landmass during ISM breaks. By conducting sensitivity experiments using a simplified global atmospheric general circulation model forced with satellite-derived three-dimensional LH, it is demonstrated that the combined effects of the enhanced LH over the CEH foothills and Indo-China and decreased LH over the Indian landmass during ISM breaks are pivotal for generating the poleward extending meridional wave train and the ACMCC anomaly. At the same time, the spatial extent of the mid-latitude cyclonic anomaly over Far-East Asia is also influenced by the anomalous LH over central–eastern China. While the present findings provide interesting insights into the role of LH anomalies during ISM breaks on the poleward extending meridional wave train, the ACMCC anomaly is found to have important ramifications on the daily rainfall extremes over the Indo-China region. It is revealed from the present analysis that the frequency of extreme rainfall occurrences over Indo-China shows a twofold increase during ISM break periods as compared to active ISM conditions.

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