Analysis of variations of cloud and aerosol properties associated with active and break spells of Indian summer monsoon using MODIS data

Kiran, V. Ravi; Rajeevan, M.; Rao, S. Vijaya Bhaskara; Rao, N. Kameswara

doi:10.1029/2008gl037135

Cited by 45 publications

(17 citation statements)

References 14 publications

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“…Thus there exists a great range of spatial asymmetry of AOD across the country. A maximum value of AOD (of the order of 1.0 or more; Ravi Kiran et al 2009) is observed over the IGP region. Furthermore it is interesting to note that the location of the maximum loading of aerosols during break monsoon condition is located north of but parallel to the climatological position of the monsoon trough.…”

Section: Aerosol Loading and Its Anomalies During Bfa Casesmentioning

confidence: 99%

“…The red dotted lines represent trajectories at 500 m, the green ones at 1,500 m and the blue lines portray those at 3,000 m. Furthermore, all the three trajectories are originating from the two different locations mentioned above. Thus it can be attributed that the anomalous aerosol loading is due to long range transport plus amplification by local input in a large-scale subsidence backdrop (Ravi Kiran et al 2009). …”

Section: Source Region Of Aerosolsmentioning

confidence: 99%

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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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Section: Aerosol Loading and Its Anomalies During Bfa Casesmentioning

confidence: 99%

Section: Source Region Of Aerosolsmentioning

confidence: 99%

Absorbing aerosols facilitate transition of Indian monsoon breaks to active spells

et al. 2010

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“…Our speculation is that the type of aerosols and aerosol loading in 2009 as compared to 2008 also played an important role, affecting cloud formation and in turn suppressing precipitation. There is a strong debate that, aerosols cannot play the role of initiators that could trigger long breaks (which accumulate to drought like situation), and that the aerosols and their variability is only an after-effect of the monsoon (aerosol wash out or persistence of aerosol plumes in the absence of precipitation) (Kiran et al, 2009). Though it is true that the drought like conditions cause the observed aerosol variability, it is subject to the time period of study, i.e., if the aerosol variability is investigated after the onset of the monsoon, this assumption is applicable.…”

Section: Discussionmentioning

confidence: 99%

Aerosol-Cloud-Interaction Variability Induced by Atmospheric Brown Clouds during the 2009 Indian Summer Monsoon Drought

Bhawar

Rahul

2013

Aerosol Air Qual. Res.

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Contrasting monsoons of 2008 and 2009 provided a test bed to enhance the understanding of the aerosol variability and aerosol-cloud interaction. Vertical aerosol profiles derived from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) are used to delineate the aerosol properties during the two contrasting Indian summer monsoons. We observed a 30-40% increase in the aerosol occurrence frequency (AOF) in lower altitudes (below 6 km) in 2009 and a 5-8% enhancement in AOF at higher altitudes in 2008. The cloud occurrence frequency also showed more deep convective clouds in 2008 (13-15%) than in 2009. Cloud Fraction, Aerosol Optical Depth and TRMM precipitation data sets have been also used to investigate the aerosol-cloud interaction. We define the microphysical effect as the increase in cloud fraction with increase in aerosols (CCN) and the radiative effect as the decrease of cloud fraction with increase in aerosol loading. We observe a stronger microphysical effect than the radiative effect in 2008 as compared to 2009. In 2009, atmospheric brown clouds were observed from March to September, which slowed down the microphysical effect and enhanced the radiative effect. This resulted in a 30% reduction in the total cloud fraction that may have reduced precipitation, and invigorated the drought conditions during 2009.

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“…Over the Indian region, only a limited number of studies have been done on the aerosol indirect effects. Using MODerate resolution Imaging Spectroradiometer (MODIS) data these studies both qualitatively and quantitatively suggest that there exists a significant positive aerosol indirect effect over IGP and is one of the factors that modulate the Indian summer monsoon (Patra et al, 2005;Ravi Kiran et al, 2009;Panicker et al, 2010). However, it is still uncertain how much the accumulation of aerosols in the non-monsoon months affects the onset and progress of succeeding monsoon season.…”

Section: Introductionmentioning

confidence: 99%

Role of fine mode aerosols in modulating cloud properties over industrial locations in north India

Abish

Mohanakumar

2011

Ann. Geophys.

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Abstract. The influence of aerosols on cloud properties over North India which includes the Indo-Gangetic Plain has been investigated for the years 2000 to 2010. During the years 2004, 2009 and 2010 there has been an abrupt increase in fine mode aerosol optical depth (AOD) inducing a sharp decline in cloud effective radius (CER) in the month of January. The following monsoon during these years was a failure in the region considered for the study. In the year 2010, a highest AOD value of 0.35 was recorded in the month of January. In accordance with the aerosol indirect effect, this large increase in AOD resulted in a significant reduction in CER. The monsoon season in that year was deficient in the study region even though the rest of the country received above normal rainfall. For the years when CER diminished below 12 microns in the month of May, a delay in the advancement of monsoon towards North India is noted even after a normal or early onset in southern peninsula. Meanwhile, a rapid progression took place when it was 12 microns or above. During non-monsoon months an inverse relationship existed between cloud effective radius and liquid water path and a strong positive association occurred in the monsoon months. Present analysis suggests that the excessive aerosol loading and the associated aerosol indirect effects in the months prior to the monsoon season has an effect on the propagation and onset of the south west monsoon over the region.

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Analysis of variations of cloud and aerosol properties associated with active and break spells of Indian summer monsoon using MODIS data

Cited by 45 publications

References 14 publications

Absorbing aerosols facilitate transition of Indian monsoon breaks to active spells

Absorbing aerosols facilitate transition of Indian monsoon breaks to active spells

Aerosol-Cloud-Interaction Variability Induced by Atmospheric Brown Clouds during the 2009 Indian Summer Monsoon Drought

Role of fine mode aerosols in modulating cloud properties over industrial locations in north India

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