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 ◽  
...  
2021 ◽  
Vol 7 (23) ◽  
pp. eabg3848
Author(s):  
Steven C. Clemens ◽  
Masanobu Yamamoto ◽  
Kaustubh Thirumalai ◽  
Liviu Giosan ◽  
Julie N. Richey ◽  
...  

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.


2016 ◽  
Vol 37 (1) ◽  
pp. 94-108 ◽  
Author(s):  
Ruiqing Li ◽  
Shihua Lv ◽  
Bo Han ◽  
Yanhong Gao ◽  
Xianhong Meng

2020 ◽  
Author(s):  
Laura Wilcox ◽  
Zhen Liu ◽  
Bjørn Samset ◽  
Ed Hawkins ◽  
Marianne Lund ◽  
...  

<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>


2020 ◽  
Author(s):  
Laura J. Wilcox ◽  
Zhen Liu ◽  
Bjørn H. Samset ◽  
Ed Hawkins ◽  
Marianne T. Lund ◽  
...  

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.


2020 ◽  
Vol 20 (20) ◽  
pp. 11955-11977 ◽  
Author(s):  
Laura J. Wilcox ◽  
Zhen Liu ◽  
Bjørn H. Samset ◽  
Ed Hawkins ◽  
Marianne T. Lund ◽  
...  

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.


2021 ◽  
Author(s):  
Dipanjan Dey ◽  
Kristofer Döös

<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>


2015 ◽  
Vol 28 (8) ◽  
pp. 3400-3419 ◽  
Author(s):  
Rui Mei ◽  
Moetasim Ashfaq ◽  
Deeksha Rastogi ◽  
L. Ruby Leung ◽  
Francina Dominguez

Abstract This paper analyzes a suite of global climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) archives to understand the mechanisms behind a net increase in the South Asian summer monsoon precipitation in response to enhanced radiative forcing during the twenty-first century. An increase in radiative forcing fuels an increase in the atmospheric moisture content through warmer temperatures, which overwhelms the weakening of monsoon circulation and results in an increase of moisture convergence and therefore summer monsoon precipitation over South Asia. Moisture source analysis suggests that both regional (local recycling, the Arabian Sea, the Bay of Bengal) and remote (including the south Indian Ocean) sources contribute to the moisture supply for precipitation over South Asia during the summer season that is facilitated by the monsoon dynamics. For regional moisture sources, the effect of excessive atmospheric moisture is offset by weaker monsoon circulation and uncertainty in the response of the evapotranspiration over land, so anomalies in their contribution to the total moisture supply are either mixed or muted. In contrast, weakening of the monsoon dynamics has less influence on the moisture supply from remote sources that not only is a dominant moisture contributor in the historical period but is also the net driver of the positive summer monsoon precipitation response in the twenty-first century. The results also indicate that historic measures of the monsoon dynamics may not be well suited to predict the nonstationary moisture-driven South Asian summer monsoon precipitation response in the twenty-first century.


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