Irrigation-Induced Land–Atmosphere Feedbacks and Their Impacts on Indian Summer Monsoon

From the 1980s, Indian summer monsoon rainfall (ISMR) shows a decreasing trend over north and northwest India, and there was a significant observed reduction in July over central and south India in 1982–2003. The key drivers of the changed ISMR, however, remain unclear. It was hypothesized that the large-scale irrigation development that started in the 1950s has resulted in land surface cooling, which slowed large-scale atmospheric circulation, exerting significant influences on ISMR. To test this hypothesis, a fully coupled model, the CESM v1.0.3, was used with a global irrigation dataset. In this study, spatially varying irrigation-induced feedback mechanisms are investigated in detail at different stages of the monsoon. Results show that soil moisture and evapotranspiration increase significantly over India throughout the summertime because of the irrigation. However, 2-m air temperature shows a significant reduction only in a limited region because the temperature change is influenced simultaneously by surface incoming shortwave radiation and evaporative cooling resulting from the irrigation, especially over the heavily irrigated region. Irrigation also induces a 925-hPa northeasterly wind from 30°N toward the equator. This is opposite to the prevailing direction of the Indian summer monsoon (ISM) wind that brings moist air to India. The modeled rainfall in the irrigated case significantly decreases up to 1.5 mm day−1 over central and north India from July to September. This paper reveals that the irrigation can contribute to both increasing and decreasing the surface temperature via multiple feedback mechanisms. The net effect is to weaken the ISM with the high spatial and temporal heterogeneity.

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Absorbing Aerosols and Summer Monsoon Evolution over South Asia: An Observational Portrayal

Journal of Climate ◽

10.1175/2007jcli2094.1 ◽

2008 ◽

Vol 21 (13) ◽

pp. 3221-3239 ◽

Cited By ~ 112

Author(s):

Massimo Bollasina ◽

Sumant Nigam ◽

K-M. Lau

Keyword(s):

Summer Monsoon ◽

Land Surface ◽

Large Scale ◽

Cloud Amount ◽

Shortwave Radiation ◽

Monsoon Circulation ◽

Gangetic Plain ◽

Surface Warming ◽

Absorbing Aerosols

Abstract The South Asian haze builds up from December to May, is mostly of anthropogenic origin, and absorbs part of the solar radiation. The influence of interannual variations of absorbing aerosols over the Indo-Gangetic Plain in May on the Indian summer monsoon is characterized by means of an observational analysis. Insight into how the aerosol impact is generated is also provided. It is shown that anomalous aerosol loading in late spring leads to remarkable and large-scale variations in the monsoon evolution. Excessive aerosols in May lead to reduced cloud amount and precipitation, increased surface shortwave radiation, and land surface warming. The June (and July) monsoon anomaly associated with excessive May aerosols is of opposite sign over much of the subcontinent (although with a different pattern) with respect to May. The monsoon strengthens in June (and July). The analysis suggests that the significant large-scale aerosol influence on monsoon circulation and hydroclimate is mediated by the heating of the land surface, pursuant to reduced cloudiness and precipitation in May. The finding of the significant role of the land surface in the realization of the aerosol impact is somewhat novel.

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Oceanic factors controlling the Indian summer monsoon onset in a coupled model

Climate Dynamics ◽

10.1007/s00382-014-2200-y ◽

2014 ◽

Vol 44 (3-4) ◽

pp. 977-1002 ◽

Cited By ~ 30

Author(s):

Chloé Prodhomme ◽

Pascal Terray ◽

Sébastien Masson ◽

Ghyslaine Boschat ◽

Takeshi Izumo

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Coupled Model ◽

Monsoon Onset ◽

Summer Monsoon Onset

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Large-scale extreme rainfall producing synoptic systems of the Indian summer monsoon

10.1002/essoar.10502887.1 ◽

2020 ◽

Author(s):

Akshaya C Nikumbh ◽

Arindam Chakraborty ◽

G S Bhat ◽

Dargan M. W. Frierson

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Large Scale ◽

Extreme Rainfall

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Theoretical aspects of the onset of Indian summer monsoon from perturbed orography simulations in a GCM

Annales Geophysicae ◽

10.5194/angeo-24-2075-2006 ◽

2006 ◽

Vol 24 (8) ◽

pp. 2075-2089 ◽

Cited By ~ 56

Author(s):

A. Chakraborty ◽

R. S. Nanjundiah ◽

J. Srinivasan

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

General Circulation ◽

Large Scale ◽

Vertical Motion ◽

Circulation Model ◽

Threshold Value ◽

The Earth ◽

Static Energy ◽

The Impact

Abstract. A theory is proposed to determine the onset of the Indian Summer Monsoon (ISM) in an Atmospheric General Circulation Model (AGCM). The onset of ISM is delayed substantially in the absence of global orography. The impact of orography over different parts of the Earth on the onset of ISM has also been investigated using five additional perturbed simulations. The large difference in the date of onset of ISM in these simulations has been explained by a new theory based on the Surface Moist Static Energy (SMSE) and vertical velocity at the mid-troposphere. It is found that onset occurs only after SMSE crosses a threshold value and the large-scale vertical motion in the middle troposphere becomes upward. This study shows that both dynamics and thermodynamics play profound roles in the onset of the monsoon.

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Global Extratropical Response to Diabatic Heating Variability of the Asian Summer Monsoon

Journal of the Atmospheric Sciences ◽

10.1175/2009jas3008.1 ◽

2009 ◽

Vol 66 (9) ◽

pp. 2697-2713 ◽

Cited By ~ 73

Author(s):

Hai Lin

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

North Pacific ◽

Western North Pacific ◽

Large Scale ◽

Asian Summer Monsoon ◽

Convective Activity ◽

Mean Flow ◽

Asian Summer ◽

Circulation Anomalies

Abstract Global teleconnections associated with the Asian summer monsoon convective activities are investigated based on monthly data of 29 Northern Hemisphere summers defined as June–September (JJAS). Two distinct teleconnection patterns are identified that are associated respectively with variabilities of the Indian summer monsoon and the western North Pacific summer monsoon. The Indian summer monsoon convective activity is associated with a global pattern that has a far-reaching connection in both hemispheres, whereas the western North Pacific summer monsoon convective activity is connected to a Southern Hemisphere wave train that influences the high-latitude South Pacific and South America. A global primitive equation model is utilized to assess the cause of the global circulation anomalies. The model responses to anomalous heatings of both monsoon systems match the general features of the observed circulation anomalies well, and they are mainly controlled by linear processes. The response patterns are largely determined by the summertime large-scale background mean flow and the location of the heating anomaly relative to the upper easterly jet in the monsoon region.

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Role of the Indian Ocean in the Biennial Transition of the Indian Summer Monsoon

Journal of Climate ◽

10.1175/jcli4127.1 ◽

2007 ◽

Vol 20 (10) ◽

pp. 2147-2164 ◽

Cited By ~ 19

Author(s):

Renguang Wu ◽

Ben P. Kirtman

Keyword(s):

Indian Ocean ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Indian Monsoon ◽

Coupled Model ◽

The Pacific ◽

The Indian Ocean ◽

Biennial Variability ◽

Sst Anomalies

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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Impact of stratospheric aerosol intervention geoengineering on surface air temperature in China: A surface energy budget perspective

10.5194/acp-2021-503 ◽

2021 ◽

Author(s):

Zhaochen Liu ◽

Xianmei Lang ◽

Dabang Jiang

Keyword(s):

Spatial Pattern ◽

Air Temperature ◽

Land Surface ◽

Surface Albedo ◽

Surface Air Temperature ◽

Stratospheric Aerosol ◽

Surface Energy Budget ◽

Shortwave Radiation ◽

Surface Cooling ◽

Temperature Changes

Abstract. Stratospheric aerosol intervention (SAI) geoengineering is a rapid, effective, and promising means to counteract anthropogenic global warming, but the climate response to SAI, with great regional disparities, remains uncertain. In this study, we use Geoengineering Model Intercomparison Project G4 experiment simulations from three models (HadGEM2-ES, MIROC-ESM, and MIROC-ESM-CHEM) that offset anthropogenic forcing under medium-low emissions (RCP4.5) by injecting a certain amount of SO2 into the stratosphere every year, to investigate the surface air temperature response to SAI geoengineering over China. It has been shown that the SAI leads to surface cooling over China over the last 40 years of injection simulation (2030–2069), which varies among models, regions and seasons. The spatial pattern of SAI-induced temperature changes over China is mainly due to net surface shortwave radiation changes. We find that changes in solar radiation modification strength, surface albedo, atmospheric water vapor and cloudiness affect surface shortwave radiation. In summer, the increased cloud cover in some regions reduces net surface shortwave radiation, causing strong surface cooling. In winter, both the strong cooling in all three models and the abnormal warming in MIROC-ESM are related to surface albedo changes. Our results suggest that cloud and land surface processes in models may dominate the spatial pattern of SAI-induced surface air temperature changes over China.

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Regionalization of seasonal precipitation over the Tibetan Plateau and associated large-scale atmospheric systems

Journal of Climate ◽

10.1175/jcli-d-20-0521.1 ◽

2020 ◽

pp. 1-45

Author(s):

Hui-Wen Lai ◽

Hans W. Chen ◽

Julia Kukulies ◽

Tinghai Ou ◽

Deliang Chen

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Indian Summer Monsoon ◽

Large Scale ◽

Late Summer ◽

Early Summer ◽

The Tibetan Plateau ◽

Summer Peak ◽

Precipitation Seasonality ◽

Winter Peak

AbstractPrecipitation over the Tibetan Plateau (TP) has major societal impacts in South and East Asia, but its spatiotemporal variations are not well understood mainly because of the sparsely distributed in-situ observation sites. With help of the Global Precipitation Measurement satellite product IMERG and ERA5 reanalysis, distinct precipitation seasonality features over the TP were objectively classified using a self-organizing map algorithm fed with ten-day averaged precipitation from 2000 to 2019. The classification reveals three main precipitation regimes with distinct seasonality of precipitation: winter peak, centered at the western plateau; early summer peak, found on the eastern plateau; and late summer peak, mainly located on the southwestern plateau. On a year-to-year basis, the winter peak regime is relatively robust, while the early summer and late summer peak regimes tend to shift mainly between the central and northern TP, but are robust in the eastern and southwestern TP. A composite analysis shows that the winter peak regime experiences larger amounts of precipitation in winter and early spring when the westerly jet is anomalously strong to the north of the TP. Precipitation variations in the late summer peak regime are associated with intensity changes in the South Asian High and Indian summer monsoon. The precipitation in the early summer peak regime is correlated with the Indian summer monsoon together with anticyclonic circulation over the western North Pacific. The results provide a basic understanding of precipitation seasonality variations over the TP and associated large-scale conditions.

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