Aerosol indirect effects from ground‐based retrievals over the rain shadow region in Indian subcontinent

Harikishan, G.; Padmakumari, B.; Maheskumar, R. S.; Pandithurai, G.; Min, Qilong

doi:10.1002/2015jd024577

Cited by 16 publications

(13 citation statements)

References 58 publications

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“…Based on equation 1, values of the FIE at the SGP site in Figure 4 e phenomenon that increases in FIE as LWP increases at the SGP site is not consistent with that at the SACOL site. For current studies, the dependence of FIE on the LWP over California coast [64], the East China Sea [65], southeast Pacific [66], Nordic Countries [67], and Indian subcontinent [68] showed positive correlations, but it showed negative correlations at Pt. Reyes, California [69], and Azores [20].…”

Section: Aerosol Impact On Cloud Droplet Sizementioning

confidence: 67%

“…For comparison purpose, all values are converted to the form (−z ln r e /z ln α) LWP , which is equivalent to ((1/3)(z ln N d /z ln α)) [72]. Different CCN proxies, such as aerosol number concentration, aerosol index, AOD, and aerosol scattering coefficient, would also bring discrepancy in FIE values, which were seldom considered in previous works [68,70,72]. In Figure 5, different CCN proxies are marked with different symbols.…”

Section: Aerosol Impact On Cloud Droplet Sizementioning

confidence: 99%

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Ten Years of Aerosol Effects on Single-Layer Overcast Clouds over the US Southern Great Plains and the China Loess Plateau

Yan

Wang

2020

Advances in Meteorology

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Using almost 10 years of observations of clouds and aerosols from the US Southern Great Plains (SGP) atmospheric observatory and the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) in China, the impact of aerosols on single-layer overcast clouds over continental land for different regimes were investigated. Atmospheric conditions at the two sites were first compared in an attempt to isolate the influence of aerosols on cloud properties from dynamic and thermodynamic influences. Cloud types and amounts are similar at the two sites. The dominant aerosol types at the SGP and SACOL sites are sulphate and dust, respectively, with greater aerosol optical depths (AODs) and absorption at the SACOL site. Aerosol first indirect effect (FIE) ranges from 0.021 to 0.152 and from −0.078 to 0.047 at the SGP and SACOL sites, respectively, when using the AOD below cloud base as CCN proxy. Although differences exist, the influence of meteorological conditions on the FIE at the two sites is consistent. FIEs are easily detected under descending motion and dry condition. The FIE at the SGP site is larger than that at the SACOL site, which suggests that the cloud albedo effect is more sensitive under relatively cleaner atmospheric conditions and the dominating aerosol at the SACOL site has less hygroscopicity. The radiative forcing of the FIE over the SGP site is −3.2 W m−2 for each 0.05 increment in FIE. Cloud durations generally prolong as aerosol loading increases, which is consistent with the hypothesis of the aerosol second indirect effect. The negative relationship between cloud duration time and aerosol loading when aerosol loading reaches a large value further might suggest a semidirect effect.

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Section: Aerosol Impact On Cloud Droplet Sizementioning

confidence: 67%

Section: Aerosol Impact On Cloud Droplet Sizementioning

confidence: 99%

Ten Years of Aerosol Effects on Single-Layer Overcast Clouds over the US Southern Great Plains and the China Loess Plateau

Yan

Wang

2020

Advances in Meteorology

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“…Under high-aerosol conditions, LWP changes little as LTS increases. A likely reason is inhibited cloud droplet sedimentation due to the reduced cloud droplet size, enhancing evaporation and entrainment at the cloud top and reducing LWP (Kaufman et al, 2005;Hill et al, 2009;Zhao and Garrett, 2015;Liu et al, 2016). There are similar variations in DER with increasing LTS under low-and high-aerosol conditions (bottom panels of Fig.…”

Section: Aerosol Effects On the Dependence Of Cloud Properties On Metmentioning

confidence: 73%

Aerosol properties and their influences on low warm clouds during the Two-Column Aerosol Project

2019

Atmos. Chem. Phys.

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Abstract. Twelve months of measurements collected during the Two-Column Aerosol Project field campaign at Cape Cod, Massachusetts, which started in the summer of 2012, were used to investigate aerosol physical, optical, and chemical properties and their influences on the dependence of cloud development on thermodynamic (i.e., lower tropospheric stability, LTS) conditions. Relationships between aerosol loading and cloud properties under different dominant air-mass conditions and the magnitude of the first indirect effect (FIE), as well as the sensitivity of the FIE to different aerosol compositions, are examined. The seasonal variation in aerosol number concentration (Na) was not consistent with variations in aerosol optical properties (i.e., scattering coefficient, σs, and columnar aerosol optical depth). Organics were found to have a large contribution to small particle sizes. This contribution decreased during the particle growth period. Under low-aerosol-loading conditions, the liquid water path (LWP) and droplet effective radius (DER) significantly increased with increasing LTS, but, under high-aerosol-loading conditions, LWP and DER changed little, indicating that aerosols significantly weakened the dependence of cloud development on LTS. The reduction in LWP and DER from low- to high-aerosol-loading conditions was greater in stable environments, suggesting that clouds under stable conditions are more susceptible to aerosol perturbations than those under more unstable conditions. High aerosol loading weakened the increase in DER as LWP increased and strengthened the increase in cloud optical depth (COD) with increasing LWP, resulting in changes in the interdependence of cloud properties. Under both continental and marine air-mass conditions, high aerosol loading can significantly increase COD and decrease LWP and DER, narrowing their distributions. Magnitudes of the FIE estimated under continental air-mass conditions ranged from 0.07±0.03 to 0.26±0.09 with a mean value of 0.16±0.03 and showed an increasing trend as LWP increased. The calculated FIE values for aerosols with a low fraction of organics are greater than those for aerosols with a high fraction of organics. This implies that clouds over regions dominated by aerosol particles containing mostly inorganics are more susceptible to aerosol perturbations, resulting in larger climate forcing, than clouds over regions dominated by organic aerosol particles.

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“…Over the Indian region, previous studies have compared MODIS-observed cloud microphysical properties between low-and high-aerosol loading to demonstrate the aerosol microphysical effect and its linkage to interannual variations in seasonal rainfall (Abish and Mohanakumar, 2011;Panicker et al, 2010;Ramachandran and Kedia, 2013). Aerosol impacts on cloud microphysics over central India based on ground-based measurements are also evident (Harikishan et al, 2016;Tripathi et al, 2007). Aircraft measurements during the CAIPEEX campaign over the ISMR have provided unprecedented evidence of the aerosol microphysical effect on cloud droplet distribution and warm rainfall suppression over the ISMR (Konwar et al, 2012;Pandithurai et al, 2012;Prabha et al, 2011).…”

Section: The Effect Of Underrepresentation Of the Wet-scavenging Effementioning

confidence: 97%

Investigation of the aerosol–cloud–rainfall association over the Indian summer monsoon region

et al. 2017

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Abstract. Monsoonal rainfall is the primary source of surface water in India. Using 12 years of in situ and satellite observations, we examined the association of aerosol loading with cloud fraction, cloud top pressure, cloud top temperature, and daily surface rainfall over the Indian summer monsoon region (ISMR). Our results showed positive correlations between aerosol loading and cloud properties as well as rainfall. A decrease in outgoing longwave radiation and an increase in reflected shortwave radiation at the top of the atmosphere with an increase in aerosol loading further indicates a possible seminal role of aerosols in the deepening of cloud systems. Significant perturbation in liquid-and icephase microphysics was also evident over the ISMR. For the polluted cases, delay in the onset of collision-coalescence processes and an enhancement in the condensation efficiency allows for more condensate mass to be lifted up to the mixed colder phases. This results in the higher mass concentration of larger-sized ice-phase hydrometeors and, therefore, implies that the delayed rain processes eventually lead to more surface rainfall. A numerical simulation of a typical rainfall event case over the ISMR using a spectral bin microphysical scheme coupled with the Weather Research Forecasting (WRF-SBM) model was also performed. Simulated microphysics also illustrated that the initial suppression of warm rain coupled with an increase in updraft velocity under high aerosol loading leads to enhanced super-cooled liquid droplets above freezing level and ice-phase hydrometeors, resulting in increased accumulated surface rainfall. Thus, both observational and numerical analysis suggest that high aerosol loading may induce cloud invigoration, thereby increasing surface rainfall over the ISMR. While the meteorological variability influences the strength of the observed positive association, our results suggest that the persistent aerosol-associated deepening of cloud systems and an intensification of surface rain amounts was applicable to all the meteorological sub-regimes over the ISMR. Hence, we believe that these results provide a step forward in our ability to address aerosol-cloud-rainfall associations based on satellite observations over the ISMR.

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Aerosol indirect effects from ground‐based retrievals over the rain shadow region in Indian subcontinent

Cited by 16 publications

References 58 publications

Ten Years of Aerosol Effects on Single-Layer Overcast Clouds over the US Southern Great Plains and the China Loess Plateau

Ten Years of Aerosol Effects on Single-Layer Overcast Clouds over the US Southern Great Plains and the China Loess Plateau

Aerosol properties and their influences on low warm clouds during the Two-Column Aerosol Project

Investigation of the aerosol–cloud–rainfall association over the Indian summer monsoon region

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