Seasonal and vertical distributions of aerosol type extinction coefficients with an emphasis on the impact of dust aerosol on the microphysical properties of cirrus over the Taklimakan Desert in Northwest China

Abstract. The direct radiative forcing efficiency of dust aerosol (DRFEdust) is an important indicator to measure the climate effect of dust. The DRFEdust is determined by the microphysical properties of dust, which vary with dust source regions. However, there are only sparse in situ measurements of them, such as the distribution of the dust aerosol particle size and the complex refractive index in the main dust source regions. Furthermore, recent studies have shown that the non-spherical effect of the dust particle is not negligible. The DRFEdust is often evaluated by estimating given microphysical properties of the dust aerosols in the radiative transfer model (RTM). However, considerable uncertainties exist due to the complex and variable dust properties, including the complex refractive index and the shape of the dust. The DRFEdust over the Taklimakan Desert and Sahara is derived from the satellite observations in this paper. The advantage of the proposed satellite-based method is that there is no need to consider the microphysical properties of the dust aerosols in estimating the DRFEdust. For comparison, the observed DRFEdust is compared with that simulated by the RTM. The differences in the dust microphysical properties in these two regions and their impacts on DRFEdust are analyzed. The DRFEdust derived from the satellite observation is -39.6±10.0 W m-2τ-1 in March 2019 over Tamanrasset in the Sahara and -48.6±13.7 W m-2τ-1 in April 2019 over Kashi in the Taklimakan Desert. According to the analyses of their microphysical properties and optical properties, the dust aerosols from the Taklimakan Desert (Kashi) scatter strongly. The RTM-simulated results (−41.5 to −47.4 W m-2τ-1 over Kashi and −32.2 to −44.3 W m-2τ-1 over Tamanrasset) are in good agreement with the results estimated by satellite observations. According to previous studies, the results in this paper are proven to be reasonable and reliable. The results also show that the microphysical properties of the dust can significantly influence the DRFEdust. The satellite-derived results can represent the influence of the dust microphysical properties on the DRFEdust, which can also validate the direct radiative effect of the dust aerosol and the DRFEdust derived from the numerical model more directly.

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Solar radiative forcing of aerosol particles near the Taklimakan desert during the Dust Aerosol Observation-Kashi campaign in Spring 2019

10.5194/acp-2020-60 ◽

2020 ◽

Author(s):

Li Li ◽

Zhengqiang Li ◽

Wenyuan Chang ◽

Yang Ou ◽

Philippe Goloub ◽

...

Keyword(s):

Land Surface ◽

Radiative Forcing ◽

Surface Albedo ◽

Dust Aerosol ◽

Dust Particles ◽

Taklimakan Desert ◽

Aerosol Radiative Forcing ◽

Microphysical Properties ◽

The Taklimakan Desert ◽

Cooling Effects

Abstract. The Taklimakan desert is a main and continuous source of Asian dust particles causing a significant direct aerosol solar radiative forcing (ASRF). In order to improve the accuracy of the estimation of dust radiative forcing effects, the Dust Aerosol Observation-Kashi (DAO-K) campaign was carried out near the Taklimakan desert in April 2019. The objective of the campaign is to provide comprehensive parameters such as: dust optical and microphysical properties, vertical distribution and surface albedo, for the calculation of ASRF. The measurements were employed in radiative transfer (RT) simulations and the estimations are improved by considering the actual measured atmospheric profiles and diurnal variations of land surface albedo in addition to reliable aerosol parameters. The RT model estimates the ASRF results in average daily mean cooling effects of −19 W m−2 at the top of atmosphere and −36 W m−2 at the bottom of atmosphere during the DAO-K campaign. The Weather Research and Forecasting model with Chemistry (WRF-Chem) with assimilations of the aerosol optical depth and PM2.5 and PM10 concentrations measurements is prone to overestimate the radiative forcing effects of dust aerosols. The percent difference of daily mean ASRF between the two simulations are greater than 50 % in heavy dust episode. Ground-based observations of downward irradiances have validated that the RT simulations are in good agreement with simultaneous observations, whereas the WRF-Chem estimations exhibit obvious discrepancy with these independent measurements. Data assimilations can partly reduce the discrepancy, but there is still room for improving the WRF-Chem simulation of dust aerosol radiative forcing.

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Aerosol solar radiative forcing near the Taklimakan Desert based on radiative transfer and regional meteorological simulations during the Dust Aerosol Observation-Kashi campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-10845-2020 ◽

2020 ◽

Vol 20 (18) ◽

pp. 10845-10864 ◽

Cited By ~ 1

Author(s):

Li Li ◽

Zhengqiang Li ◽

Wenyuan Chang ◽

Yang Ou ◽

Philippe Goloub ◽

...

Keyword(s):

Radiative Transfer ◽

Solar Irradiance ◽

Radiative Forcing ◽

Surface Albedo ◽

Dust Aerosol ◽

Dust Particles ◽

Taklimakan Desert ◽

Microphysical Properties ◽

The Taklimakan Desert ◽

Aerosol Parameters

Abstract. The Taklimakan Desert is a main and continuous source of Asian dust particles causing significant direct radiative effects, which are commonly quantified by the aerosol solar radiative forcing (ASRF). To improve the accuracy of estimates of dust ASRF, the Dust Aerosol Observation-Kashi (DAO-K) campaign was carried out near the Taklimakan Desert in April 2019. The objective of the DAO-K campaign is to provide crucial parameters needed for the calculation of ASRF, such as dust optical and microphysical properties, vertical distribution, and surface albedo. The ASRF was calculated using radiative transfer (RT) simulations based on the observed aerosol parameters, additionally considering the measured atmospheric profiles and diurnal variations of surface albedo. As a result, daily average values of ASRF of −19 W m−2 at the top of the atmosphere and −36 W m−2 at the bottom of the atmosphere were derived from the simulations conducted during the DAO-K campaign. Furthermore, the Weather Research and Forecasting model with Chemistry (WRF-Chem), with assimilation of measurements of the aerosol optical depth and particulate matter (PM) mass concentrations of particles with aerodynamic diameter smaller than 2.5 µm (PM2.5) and 10 µm (PM10), is employed to estimate the dust ASRF for comparison. The results of the ASRF simulations (RT and WRF-Chem) were evaluated using ground-based downward solar irradiance measurements, which have confirmed that the RT simulations are in good agreement with simultaneous observations, whereas the WRF-Chem estimations reveal obvious discrepancies with the solar irradiance measurements.

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Estimating Radiative Forcing Efficiency of Dust Aerosol Based on Direct Satellite Observations: Case Studies over the Sahara Desert and Taklimakan Desert

10.5194/acp-2020-1113 ◽

2021 ◽

Author(s):

Lin Tian ◽

Lin Chen ◽

Peng Zhang ◽

Lei Bi

Keyword(s):

Radiative Forcing ◽

Complex Refractive Index ◽

Satellite Observations ◽

Dust Aerosol ◽

Taklimakan Desert ◽

Sahara Desert ◽

Dust Aerosols ◽

Microphysical Properties ◽

Source Regions ◽

The Taklimakan Desert

Abstract. The direct radiative forcing efficiency of the dust aerosol (DRFEdust) is an important indicator to measure the climate effect of the dust. The DRFEdust is determined by the microphysical properties of the dust, which vary with the dust source regions. However, there are only sparse in-situ measurements of them, such as the distribution of the dust aerosol particle size and the complex refractive index in the main dust source regions. Furthermore, recent studies have shown that the non-spherical effect of the dust particle is not negligible. The DRFEdust is often evaluated by estimating given microphysical properties of the dust aerosols in the radiative transfer model (RTM). However, considerable uncertainties exist due to the complex and variable dust properties, including the complex refractive index and the shape of the dust. The DRFEdust over the Taklimakan Desert and the Sahara Desert is derived from the satellite observations in this paper. The advantage of the proposed satellite-based method is that there is no need to consider the microphysical properties of the dust aerosols in estimating the DRFEdust. For comparison, the observed DRFEdust is compared with that simulated by the RTM. The differences in the dust microphysical properties in these two regions and their impacts on DRFEdust are analyzed. The DRFEdust derived from the satellite observation is −39.6 ± 10.0 W m−2 τ−1 in March 2019 over Tamanrasset and −48.6 ± 13.7 W m−2 τ−1 in April 2019 over Kashi. According to the analyses of their microphysical properties and optical properties, the dust aerosols from the Taklimakan desert (Kashi) scatter strongly. The RTM simulated results (−41.5 to −47.4 W m−2 τ−1 in the Taklimakan Desert and −32.2 to −44.3 W m−2 τ−1 in the Sahara Desert) are in good agreement with the results estimated by satellite observations. According to previous studies, the results in this paper are proved to be reasonable and reliable. The results also show that the microphysical properties of the dust can significantly influence the DRFEdust. The satellite-derived results can represent the influence of the dust microphysical properties on the DRFEdust, which can also validate the direct radiative effect of the dust aerosol and the DRFEdust derived from the numerical model more directly.

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Spatial and temporal variation of the near-surface wind regimes in the Taklimakan Desert, Northwest China

Theoretical and Applied Climatology ◽

10.1007/s00704-019-02824-w ◽

2019 ◽

Vol 138 (1-2) ◽

pp. 433-447 ◽

Cited By ~ 1

Author(s):

Zhengyao Liu ◽

Zhibao Dong ◽

Zhengcai Zhang ◽

Xujia Cui ◽

Nan Xiao

Keyword(s):

Temporal Variation ◽

Surface Wind ◽

Northwest China ◽

Spatial And Temporal Variation ◽

Taklimakan Desert ◽

Near Surface ◽

The Taklimakan Desert ◽

Wind Regimes

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The Impacts of Taklimakan Dust Events on Chinese Urban Air Quality in 2015

Atmosphere ◽

10.3390/atmos9070281 ◽

2018 ◽

Vol 9 (7) ◽

pp. 281 ◽

Cited By ~ 2

Author(s):

Xiaoyu Li ◽

Xiaodong Liu ◽

Zhi-Yong Yin

Keyword(s):

Air Quality ◽

Dust Storm ◽

Northwest China ◽

Urban Air Quality ◽

Urban Air ◽

Taklimakan Desert ◽

The Taklimakan Desert ◽

Pm10 And Pm2.5 ◽

Dust Events ◽

Mass Concentrations

Aerosols are an important factor affecting air quality. As the largest source of dust aerosol of East Asia, the Taklimakan Desert in Northwest China witnesses frequent dust storm events, which bring about significant impacts on the downstream air quality. However, the scope and timing of the impacts of Taklimakan dust events on Chinese urban air quality have not yet been fully investigated. In this paper, based on multi-source dust data including ground observations, satellite monitoring, and reanalysis products, as well as air quality index (AQI) and the mass concentrations of PM10 and PM2.5 at 367 urban stations in China for 2015, we examined the temporal and spatial characteristics of the impacts of the Taklimakan dust events on downstream urban air quality in China. The results show that the Taklimakan dust events severely affected the air quality of most cities in Northwest China including eastern Xinjiang, Hexi Corridor and Guanzhong Basin, and even northern Southwest China, leading to significant increases in mass concentrations of PM10 and PM2.5 in these cities correlating with the occurrence of dust events. The mass concentrations of PM10 on dust days increased by 11–173% compared with the non-dust days, while the mass concentration of PM2.5 increased by 21–172%. The increments of the mass concentrations of PM10 and PM2.5 on dust days decreased as the distances increased between the cities and the Taklimakan Desert. The influence of the Taklimakan dust events on the air quality in the downstream cities usually persisted for up to four days. The mass concentrations of PM10 and PM2.5 increased successively and the impact duration shortened gradually with increasing distances to the source area as a strong dust storm progressed toward the southeast from the Taklimakan Desert. The peaks of the PM10 concentrations in the downstream cities of eastern Xinjiang, the Hexi Corridor and the Guanzhong Basin occurred on the second, third and fourth days, respectively, after the initiation of the Taklimakan dust storm.

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The Performance of a Scale-Aware Nonlocal PBL Scheme for the Subkilometer Simulation of a Deep CBL over the Taklimakan Desert

Advances in Meteorology ◽

10.1155/2018/8759594 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Hongxiong Xu ◽

Yinjun Wang ◽

Minzhong Wang

Keyword(s):

Boundary Layer ◽

Wrf Model ◽

Northwest China ◽

Taklimakan Desert ◽

Convective Boundary ◽

Eddy Simulation ◽

The Taklimakan Desert ◽

Realistic Representation ◽

Pbl Scheme ◽

Convective Cells

Although realistic representation of the convective boundary layer (CBL) in the desert region in Northwest China is important for weather forecasts and climate simulations, evaluations of the performance of various planetary boundary layer (PBL) schemes in simulating the CBL in the region are rare. In this study, the performance of a scale-aware PBL scheme newly implemented into the Weather Research and Forecasting (WRF) model in simulating the CBL in the Taklimakan desert is evaluated based on a comparison with both the WRF-LES simulations and observations, with the focus on scale dependencies of the simulations compared to the conventional PBL scheme. A series of simulations are performed with a scale-aware PBL scheme (Shin-Hong) and the conventional PBL scheme (YSU) for a deep CBL observed at Tazhong station in the central Taklimakan on 1 July 2016. The CBL was over 5000 m deep with wider and deeper rolls than in a shallow boundary layer. The results showed that the vertical structure simulated with the Shin-Hong scheme was closer to that in both the WRF-LES (large-eddy-simulation) and observations than that simulated with the YSU. The simulation with the scale-aware scheme reproduced cellular rolls similar to those in the WRF-LES, while the conventional PBL scheme struggled to trigger intense convective cells rather than cellular rolls. The results strongly suggest that the scale-aware nonlocal PBL scheme can be used to adequately reproduce the scale and evolution of the observed rolls in the deep CBL in Taklimakan desert at subkilometer resolutions.

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