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

Bollasina, Massimo; Nigam, Sumant; Lau, K.-M.

doi:10.1175/2007jcli2094.1

Cited by 150 publications

(155 citation statements)

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“…However, a recent study of Li and Leung (2013) showed that the interdecadal summer precipitation variability in China is related to the Arctic spring warming. It has been also recently reported that the rainfall over the Indian monsoon rainfall, particularly over the northeast part, and northern China has a declining trend (Bollasina and Nigam 2008;Bollasina et al 2011) but that over the Yangzte-Huai River valley and South Korea has an increasing trend Choi et al 2010;Preethi et al 2016).…”

Section: Interannual To Interdecadal Linkages: a Reviewmentioning

confidence: 92%

Linkages between the South and East Asian summer monsoons: a review and revisit

Seo

Lee

et al. 2017

Clim Dyn

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with decaying El Niño and developing Indian Ocean sea surface temperature (SST) warming anomalies; the other is the negative inter-correlation, resulting from developing El Niño and western Pacific SST cooling. The IODM mode also has a delayed impact on the negative connection by modulating Eurasian snow cover. The observed evidence reveals that the recent intensification of the negative relationship is attributable to the strengthening of the zonal SST gradient along the Indian Ocean, western Pacific, and eastern Pacific. Analysis of experiments in the fifth phase of the Coupled Model Intercomparison Project further indicates a possibility for the negative linkage to be further enhanced under anthropogenic global warming with considerable interdecadal modulation in mid and late twentyfirst century.

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Section: Interannual To Interdecadal Linkages: a Reviewmentioning

confidence: 92%

Linkages between the South and East Asian summer monsoons: a review and revisit

Seo

Lee

et al. 2017

Clim Dyn

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“…These reasons provide a comprehensive motivation to quantify the 8272 A.-P. Hyvärinen et al: Part 1: PM and BC concentrations effect of the monsoon on aerosols in the area. In addition, it's well known that aerosols can modulate the monsoon and thus the whole water cycle (Lau and Kim, 2006;Bollasina et al, 2008;Meehl et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Effect of the summer monsoon on aerosols at two measurement stations in Northern India – Part 1: PM and BC concentrations

et al. 2011

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Abstract. Particulate matter (PM) and equivalent black carbon (BCe) concentrations were measured at two locations in northern India during [2006][2007][2008][2009][2010]. The first measurement station was a background site in Mukteshwar, about 350 km northeast of New Delhi, in the foothills of the Indian Himalayas. The second measurement site was located in Gual Pahari, about 25 km south of New Delhi. Here we focused on resolving the effects of the Indian summer monsoon on the particulate matter and equivalent black carbon concentrations at two stations. The average monsoon time concentrations were decreased by 55-70 % compared to the premonsoon average concentrations at both stations, decreasing as a function of the total local rainfall during the monsoon season. In Mukteshwar during the monsoon, the 24 h PM 2.5 concentrations were nearly always below the Indian National Air Quality Standard of 60 µg m −3 . In Gual Pahari, 13 % of days exceeded this level during the monsoon season. However, the 24 h guideline of 25 µg m −3 given by the World Health Organization was more difficult to meet. In addition to loss processes, aerosol concentrations during the early monsoon were found to be affected by primary emissions, most likely from dust events from the Thar Desert. This resulted in elevated fractions of the coarse mode, PM 2.5−10 at both stations. In Mukteshwar, additional dust contribution came from east of the station, from the Himalayan region. We also determined the characteristic transition times beCorrespondence to: A.-P. Hyvärinen (antti.hyvarinen@fmi.fi) tween the pre-monsoon, monsoon and post-monsoon. The onset and withdrawal transitions occurred faster in Mukteshwar than in Gual Pahari, both being typically less than 10 days. Transition periods in Gual Pahari took between 17 and 31 days. The shorter transition times in Mukteshwar were probably related to the more intense rains due to the mountain location, and the fact that the station was most of the time in the free troposphere.

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“…Thus, during a break, aerosol concentration builds up in central and north India through local emissions and long range transports while the north Indian Ocean remains relatively pristine. As a large fraction of these aerosols is of absorbing type (Menon 2004;Chakraborty et al 2004;Bollasina et al 2008), they would cool the surface but warm the atmospheric layer between 1 and 3 km. Such warming of the lower atmosphere over central and north India and lack of it over the north Indian Ocean would lead to a north-south temperature gradient at this level and convergence of moisture to central and north India.…”

Section: Introductionmentioning

confidence: 99%

Absorbing aerosols facilitate transition of Indian monsoon breaks to active spells

et al. 2010

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While some long breaks of monsoon intraseasonal oscillations (MISOs) are followed by active spells (BFA), some others are not (BNFA). The circulation during BFA (BNFA) cases helps (prevents) accumulation of absorbing aerosols over central India (CI) resulting in almost three times larger Aerosol Index (AI) over CI, during BFA cases compared to BNFA cases. A seminal role played by the absorbing aerosols in the transition from break to active spells is unraveled through modification of the north-south temperature gradient at lower levels. The meridional gradient of temperature at low level (DT) between aerosol-rich CI and pristine equatorial Indian Ocean is large ([6°C) and sustains for long time ([10 days) during BFA leading to significant moisture convergence to CI. The stability effect arising from surface cooling by the aerosols is overcome by the enhanced moisture convergence creating a moist static unstable atmosphere conducive for the large-scale organized convection over the CI region leading to the resurgence of active spells. The moisture convergence induced by DT was also able to overcome possible aerosol indirect effect (Twomey effect) and initiate deep convection and transition to active condition. During BNFA cases, however the maximum DT, which was weaker than the BFA cases by more than 1.5°C, could not sustain required moisture convergence and failed to lead to a sustained active spell. Using data from MODIS (MODerate resolution Imaging Spectroradiometer) onboard Terra and several other input parameters from various satellites for the period 2000-2009, the aerosol induced radiative forcing representative of two regions-the CI to the north and the pristine ocean to the south-were estimated and support the differences in observed DT during the two cases. Our results highlight the need for proper inclusion of absorbing aerosols in dynamical models for simulation of the observed variability of MISOs and their extended range prediction.

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

Cited by 150 publications

References 50 publications

Linkages between the South and East Asian summer monsoons: a review and revisit

Linkages between the South and East Asian summer monsoons: a review and revisit

Effect of the summer monsoon on aerosols at two measurement stations in Northern India – Part 1: PM and BC concentrations

Absorbing aerosols facilitate transition of Indian monsoon breaks to active spells

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