scholarly journals Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions

2021 ◽  
Vol 7 (23) ◽  
pp. eabg3848
Author(s):  
Steven C. Clemens ◽  
Masanobu Yamamoto ◽  
Kaustubh Thirumalai ◽  
Liviu Giosan ◽  
Julie N. Richey ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
South Asian ◽  
Summer Monsoon ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Precipitation Amount ◽  
Monsoon Precipitation ◽  
Orbital Eccentricity ◽  
South Asian Summer Monsoon ◽  
Asian Summer

South Asian precipitation amount and extreme variability are predicted to increase due to thermodynamic effects of increased 21st-century greenhouse gases, accompanied by an increased supply of moisture from the southern hemisphere Indian Ocean. We reconstructed South Asian summer monsoon precipitation and runoff into the Bay of Bengal to assess the extent to which these factors also operated in the Pleistocene, a time of large-scale natural changes in carbon dioxide and ice volume. South Asian precipitation and runoff are strongly coherent with, and lag, atmospheric carbon dioxide changes at Earth’s orbital eccentricity, obliquity, and precession bands and are closely tied to cross-equatorial wind strength at the precession band. We find that the projected monsoon response to ongoing, rapid high-latitude ice melt and rising carbon dioxide levels is fully consistent with dynamics of the past 0.9 million years.

scholarly journals Interannual Variability in the Large-Scale Dynamics of the South Asian Summer Monsoon

2015 ◽  
Vol 28 (9) ◽  
pp. 3731-3750 ◽  
Author(s):  
Jennifer M. Walker ◽  
Simona Bordoni ◽  
Tapio Schneider
Keyword(s):  
Interannual Variability ◽  
South Asian ◽  
Summer Monsoon ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Sea Breeze ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Near Surface ◽  
Asian Summer

Abstract This study identifies coherent and robust large-scale atmospheric patterns of interannual variability of the South Asian summer monsoon (SASM) in observational data. A decomposition of the water vapor budget into dynamic and thermodynamic components shows that interannual variability of SASM net precipitation (P − E) is primarily caused by variations in winds rather than in moisture. Linear regression analyses reveal that strong monsoons are distinguished from weak monsoons by a northward expansion of the cross-equatorial monsoonal circulation, with increased precipitation in the ascending branch. Interestingly, and in disagreement with the view of monsoons as large-scale sea-breeze circulations, strong monsoons are associated with a decreased meridional gradient in the near-surface atmospheric temperature in the SASM region. Teleconnections exist from the SASM region to the Southern Hemisphere, whose midlatitude poleward eddy energy flux correlates with monsoon strength. Possible implications of these teleconnection patterns for understanding SASM interannual variability are discussed.

scholarly journals Suppression of south Asian summer monsoon precipitation in the 21st century

2009 ◽  
Vol 36 (1) ◽  
Author(s):  
Moetasim Ashfaq ◽  
Ying Shi ◽  
Wen-wen Tung ◽  
Robert J. Trapp ◽  
Xueijie Gao ◽  
...  
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
21St Century ◽  
Asian Summer Monsoon ◽  
Monsoon Precipitation ◽  
South Asian Summer Monsoon ◽  
Asian Summer

Projections of South Asian summer monsoon precipitation based on 12 CMIP5 models

2016 ◽  
Vol 37 (1) ◽  
pp. 94-108 ◽  
Author(s):  
Ruiqing Li ◽  
Shihua Lv ◽  
Bo Han ◽  
Yanhong Gao ◽  
Xianhong Meng
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Cmip5 Models ◽  
Monsoon Precipitation ◽  
South Asian Summer Monsoon ◽  
Asian Summer

scholarly journals Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions

2020 ◽  
Author(s):  
Laura Wilcox ◽  
Zhen Liu ◽  
Bjørn Samset ◽  
Ed Hawkins ◽  
Marianne Lund ◽  
...  
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Relative Magnitude ◽  
Monsoon Precipitation ◽  
South Asian Summer Monsoon ◽  
Anthropogenic Aerosol ◽  
Asian Summer ◽  
Aerosol Emissions ◽  
The Impact

<div> <div> <div> <p>There is large uncertainty in future aerosol emissions scenarios explored in the Shared Socioeconomic Pathways (SSPs), with plausible pathways spanning a range of possibilities from large global reductions in emissions to 2050 to moderate global increases over the same period. Diversity in emissions across the pathways is particularly large over Asia. CMIP6 models indicate that rapid anthropogenic aerosol and precursor emission reductions between the present day and the 2050s lead to enhanced increases in global and Asian summer monsoon precipitation relative to scenarios with weak air quality policies. However, the effects of aerosol reductions don’t persist in precipitation to the end of the 21st century, when response to greenhouse gases dominates differences across the SSPs. The relative magnitude and spatial distribution of aerosol changes is particularly important for South Asian summer monsoon precipitation changes. Precipitation increases here are initially suppressed in SSPs 2-4.5 and 5-8.5 relative to SSP 1-1.9 and 3-7.0 when the impact of East Asian emission decreases is counteracted by that due to continued increases in South Asian emissions.</p> </div> </div> </div>

scholarly journals Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions

2020 ◽  
Author(s):  
Laura J. Wilcox ◽  
Zhen Liu ◽  
Bjørn H. Samset ◽  
Ed Hawkins ◽  
Marianne T. Lund ◽  
...  
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Relative Magnitude ◽  
Monsoon Precipitation ◽  
South Asian Summer Monsoon ◽  
Anthropogenic Aerosol ◽  
Asian Summer ◽  
Aerosol Emissions ◽  
The Impact

Abstract. There is large uncertainty in future aerosol emissions scenarios explored in the Shared Socioeconomic Pathways (SSPs), with plausible pathways spanning a range of possibilities from large global reductions in emissions to 2050 to moderate global increases over the same period. Diversity in emissions across the pathways is particularly large over Asia. Rapid anthropogenic aerosol and precursor emission reductions between the present day and the 2050s lead to enhanced increases in global and Asian summer monsoon precipitation relative to scenarios with weak air quality policies. However, the effects of aerosol reductions don't persist in precipitation to the end of the 21st century, when response to greenhouse gases dominates differences across the SSPs. The relative magnitude and spatial distribution of aerosol changes is particularly important for South Asian summer monsoon precipitation changes. Precipitation increases here are initially suppressed in SSPs 2–4.5 and 5–8.5 relative to SSP 1–1.9 and 3–7.0 when the impact of East Asian emission decreases is counteracted by that due to continued increases in South Asian emissions.

scholarly journals Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions

2020 ◽  
Vol 20 (20) ◽  
pp. 11955-11977 ◽  
Author(s):  
Laura J. Wilcox ◽  
Zhen Liu ◽  
Bjørn H. Samset ◽  
Ed Hawkins ◽  
Marianne T. Lund ◽  
...  
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Relative Magnitude ◽  
Monsoon Precipitation ◽  
South Asian Summer Monsoon ◽  
Anthropogenic Aerosol ◽  
Asian Summer ◽  
Aerosol Emissions ◽  
The Impact

Abstract. There is a large range of future aerosol emissions scenarios explored in the Shared Socioeconomic Pathways (SSPs), with plausible pathways spanning a range of possibilities from large global reductions in emissions by 2050 to moderate global increases over the same period. Diversity in emissions across the pathways is particularly large over Asia. Rapid reductions in anthropogenic aerosol and precursor emissions between the present day and the 2050s lead to enhanced increases in global and Asian summer monsoon precipitation relative to scenarios with weak air quality policies. However, the effects of aerosol reductions do not persist to the end of the 21st century for precipitation, when instead the response to greenhouse gases dominates differences across the SSPs. The relative magnitude and spatial distribution of aerosol changes are particularly important for South Asian summer monsoon precipitation changes. Precipitation increases here are initially suppressed in SSPs 2-4.5, 3-7.0, and 5-8.5 relative to SSP1-1.9 when the impact of remote emission decreases is counteracted by continued increases in South Asian emissions.

Lagrangian tracing and analysis of the South Asian summer monsoon precipitation

2021 ◽  
Author(s):  
Dipanjan Dey ◽  
Kristofer Döös
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Water Masses ◽  
Monsoon Precipitation ◽  
South Asian Summer Monsoon ◽  
The South ◽  
South Indian Ocean ◽  
South Indian ◽  
Asian Summer

<p>The water-mass sources and their variability responsible for the South Asian summer monsoon precipitation were investigated using Lagrangian atmospheric water-mass trajectories. The results indicated that water-masses from the Central and South Indian Ocean are the dominant contributors to the total South Asian summer monsoon rainfall, followed by the contribution from the local recycling, the Arabian Sea, remote sources and the Bay of Bengal. It was also found that although the direct contribution originating from the Bay of Bengal is small, it still provides a route for the water-masses that come from other regions. The outcomes further revealed that the water-masses originating from the Central and South Indian Ocean are responsible for the net precipitation over the coastal regions of the Ganges-Brahmaputra-Meghna Delta, Northeast India, Myanmar, the foothills of the Himalayas and Central-East India. Water-masses from the Arabian sea are mainly contributing to the rainfall over the Western coast and West-Central India. Summer monsoon precipitation due to the local recycling is primarily restricted to the Indo-Gangetic plain. No recycled precipitation was observed over the mountain chain along the West coast of India (Western Ghats). The inter-annual variability of the South Asian summer monsoon precipitation was found to be mainly controlled by the water-masses from the Central and South Indian Ocean.</p>

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