Effect of Aerosols on the Ice Cloud Properties Over the Tibetan Plateau

et al. 2020

Remote Sensing

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Although some studies reported the impact of black carbon (BC) on the climate over the Tibetan Plateau (TP), the contribution and mechanisms of BC affecting the water vapor transport to Tibet are not fully understood yet. Here, utilizing the satellite observations and reanalysis data, the effects of BC on the climate over the TP and water vapor transport to the Tibet were investigated by the Community Earth System Model (CESM 2.1.0). Due to the addition of BC, a positive net heat forcing (average is 0.39 W/m2) is exerted at the surface, which induces a pronounced warming effect over the TP and consequently intensifies the East Asian Summer monsoon (EASM). However, significant cooling effects in northern India, Pakistan, Afghanistan and Iran are induced due to the BC and related feedbacks, which reduces significantly the meridional land–sea thermal contrast and finally weakens the South Asian summer monsoon (SASM). Consequently, the water vapor transport to the south border is decreased due to addition of BC. Moreover, through affecting the atmospheric circulation, the BC could induce an increase in the imported water vapor from the west and east borders of the TP, and an increase outflowing away from the north border of the TP. Overall, due to the BC, the annual mean net importing water vapor over TP is around 271 Gt, which could enhance the precipitation over the TP. The results show that the mean increase in the precipitation over TP is about 0.56 mm/day.

Section: Introductionmentioning

confidence: 99%

Role and Mechanisms of Black Carbon Affecting Water Vapor Transport to Tibet

et al. 2020

Remote Sensing

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“…As observational evidence, Liu et al . () found that aerosols have a dominant influence on the daytime ice cloud droplet radius, nocturnal ice water path and ice cloud optical depth. Furthermore, Li et al .…”

Section: Introductionmentioning

confidence: 99%

Inconsistent aerosol indirect effects on water clouds and ice clouds over the Tibetan Plateau

Intl Journal of Climatology

et al. 2019

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Recently, satellites have observed that dust events are occurring more frequently over the Tibetan Plateau (TP), which implies a new issue of aerosols influencing cloud properties and presents a new challenge in research on the role of the TP in climate change. In this study, combining satellite observations with Climate Model Intercomparison Project Phase 5 (CMIP5) model simulations, the inconsistent aerosol indirect effects on the properties of water clouds and ice clouds over the TP are compared and quantified. Analyses of satellite observations show that, compared with water clouds, ice clouds are observed more frequently and are more significantly correlated with aerosols over the TP. Correspondingly, the aerosol effect on the radiative forcing of ice clouds is more significant than that on the forcing of water clouds, in which the aerosol indirect effect is dominated by the effect on the shortwave radiative forcing of ice clouds. Both observations and CMIP5 model simulation results show that, due to the variation of aerosols, changes in the ice cloud radiative forcing cover most of the TP, while changes in the water cloud radiative forcing mainly appear over the southern edge of the TP. The CMIP5 simulation results suggest that the aerosol indirect effect on the total radiative forcing of water clouds over the TP is −0.34 (±0.03) W⋅m−2, while that on the forcing of ice clouds is −0.73 (±0.03) W⋅m−2. Overall, both the model simulations and satellite results show that the indirect effect of aerosols on ice clouds is more pronounced than that on water clouds.

“…For Central Asia, Klein et al (2013) evaluated the cloud water using medium-resolution remote sensing data. Additionally, there are some studies on cloud properties over other regions, such as the Tibetan Plateau (Zhao et al, 2014;Hua et al, 2018;Liu et al, 2019a;2019b) and China (Liu et al, 2004;Shang et al, 2017) in CEA. Under the background of global warming, some researchers have focused heavily on cloud property responses.…”

Section: Introductionmentioning

confidence: 99%

Cloud ability to produce precipitation over arid and semiarid regions of Central and East Asia

Intl Journal of Climatology

et al. 2019

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Distributed across Central and East Asia (CEA) is the largest arid and semiarid (ASA) region where the air water resources are highly significant. In this study, the cloud water resources and ability of clouds to produce precipitation over the ASA region in CEA are analysed in detail. The findings of this study indicate that both the regional liquid water path (LWP) and ice water path (IWP) tend to increase over the ASA region in CEA from 1982 to 2015, where the IWP increases more significantly at a rate of 8.61 g⋅m−2⋅decade−1. Especially, the increases in LWP and IWP indicate much more significant over the semiarid area in CEA. Simultaneously, the precipitation increases slightly, except for a weak decreasing trend over the semiarid region in East Asia from 1982 to 2015. Consequently, the clouds show a decreased precipitation efficiency over most areas of the CEA region. Over the semiarid region, especially in East Asia, the precipitation amount tends to slightly decrease from 1982 to 2015, and a decreased precipitation efficiency is found over there. Overall, the precipitation efficiency of cloud indicates maximum decrease over the semiarid area, and a minimum decrease is found over the arid area of CEA during 1982–2015. A possible mechanism relating to the consequence of aerosols suppressing precipitation may exist. In future studies, more focus should be placed on the cloud precipitation mechanism over the ASA region in CEA.