Direct radiative effects of anthropogenic aerosols on Indian summer monsoon circulation

Das, Someshwar; Dey, Sagnik; Dash, S. K.

doi:10.1007/s00704-015-1444-8

Cited by 23 publications

(19 citation statements)

References 51 publications

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“…Therefore, we discuss the RF aci for both the anthropogenic and natural fraction of aerosol for a period of 6 years (2008-2013) for three different regions of south Asia ( Fig. 1; Arabian Sea (AS; 63-72 • E, 7-19 • N), Bay of Bengal (BOB; 85-94 • E, 7-19 • N) and Central India (CI; 75-84 • E, 20-30 • N)), having significantly distinct aerosol environments as a result of variations in aerosol sources and transport pathways (Cherian et al, 2013;Das et al, 2015;Tiwari et al, 2015). Additionally, we also discuss the uncertainties of the results in the following sections.…”

Section: Introductionmentioning

confidence: 99%

A new statistical approach to improve the satellite-based estimation of the radiative forcing by aerosol–cloud interactions

2017

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Abstract. In a previous study of Quaas et al. (2008) the radiative forcing by anthropogenic aerosol due to aerosol–cloud interactions, RFaci, was obtained by a statistical analysis of satellite retrievals using a multilinear regression. Here we employ a new statistical approach to obtain the fitting parameters, determined using a nonlinear least square statistical approach for the relationship between planetary albedo and cloud properties and, further, for the relationship between cloud properties and aerosol optical depth. In order to verify the performance, the results from both statistical approaches (previous and present) were compared to the results from radiative transfer simulations over three regions for different seasons. We find that the results of the new statistical approach agree well with the simulated results both over land and ocean. The new statistical approach increases the correlation by 21–23 % and reduces the error compared to the previous approach.

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Section: Introductionmentioning

confidence: 99%

A new statistical approach to improve the satellite-based estimation of the radiative forcing by aerosol–cloud interactions

2017

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“…Earlier version of the model (RegCM3) has been used to study the characteristics of summer monsoon such as precipitation and mean wind field at 850 hPa and 200 hPa [ Dash et al ., ], where aerosol field was not interactive. The RegCM4.1 model was successfully coupled to both natural and anthropogenic aerosols to examine the aerosol transport [ Nair et al ., ; Das et al ., ] and dynamical responses of Indian summer monsoon circulation to aerosol DRE [ Das et al ., , ].…”

Section: Introductionmentioning

confidence: 99%

Dust aerosol feedback on the Indian summer monsoon: Sensitivity to absorption property

et al. 2015

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We examine the sensitivity of dust radiative feedback to the dust absorption property during the Indian summer monsoon (June–September) season from 2005 to 2010 using the Regional Climate Model version 4.1. The dust direct radiative forcing at top of atmosphere switches from cooling to warming for absorbing dust over the Indian subcontinent. The dust‐induced low pressure anomaly plays a crucial role in building up large‐scale convergence particularly over the Arabian Peninsula, which strengthens the monsoon circulation leading to enhanced precipitation over India. The intensity of precipitation and wind field at 850 hPa increases over India by considering more absorbing dust. Air temperature and cloud fraction change by 20–50% in the lower to middle troposphere as a result of dynamic response due to modification in dust absorptive characteristics. Our results demonstrate that the response of monsoon circulation to dust radiative feedback is highly sensitive to dust absorption; and hence, it should be accurately represented in the models for improved simulation of monsoon precipitation. The results have important implications in case of break‐to‐active transition within the Indian summer monsoon season.

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“…Modeling study conducted by Das et al . 53 reported increase in moisture divergence with increased absorbing aerosols. Guo et al .…”

Section: Resultsmentioning

confidence: 98%

Aerosols cause intraseasonal short-term suppression of Indian monsoon rainfall

Dave

Bhushan

Venkataraman

2017

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Aerosol abundance over South Asia during the summer monsoon season, includes dust and sea-salt, as well as, anthropogenic pollution particles. Using observations during 2000–2009, here we uncover repeated short-term rainfall suppression caused by coincident aerosols, acting through atmospheric stabilization, reduction in convection and increased moisture divergence, leading to the aggravation of monsoon break conditions. In high aerosol-low rainfall regions extending across India, both in deficient and normal monsoon years, enhancements in aerosols levels, estimated as aerosol optical depth and absorbing aerosol index, acted to suppress daily rainfall anomaly, several times in a season, with lags of a few days. A higher frequency of prolonged rainfall breaks, longer than seven days, occurred in these regions. Previous studies point to monsoon rainfall weakening linked to an asymmetric inter-hemispheric energy balance change attributed to aerosols, and short-term rainfall enhancement from radiative effects of aerosols. In contrast, this study uncovers intraseasonal short-term rainfall suppression, from coincident aerosol forcing over the monsoon region, leading to aggravation of monsoon break spells. Prolonged and intense breaks in the monsoon in India are associated with rainfall deficits, which have been linked to reduced food grain production in the latter half of the twentieth century.

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Direct radiative effects of anthropogenic aerosols on Indian summer monsoon circulation

Cited by 23 publications

References 51 publications

A new statistical approach to improve the satellite-based estimation of the radiative forcing by aerosol–cloud interactions

A new statistical approach to improve the satellite-based estimation of the radiative forcing by aerosol–cloud interactions

Dust aerosol feedback on the Indian summer monsoon: Sensitivity to absorption property

Aerosols cause intraseasonal short-term suppression of Indian monsoon rainfall

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