Aerosol optical depth over the Tibetan Plateau and its relation to aerosols over the Taklimakan Desert

Abstract. The Tibetan Plateau (TP) is representative of typical clean atmospheric conditions. Aerosol optical depth (AOD) retrieved by Multi-angle Imaging SpectroRadiometer (MISR) is higher over Qaidam Basin than the rest of the TP all the year. Different monthly variation patterns of AOD are observed over the southern and northern TP, whereby the aerosol load is usually higher in the northern TP than in the southern part. The aerosol load over the northern part increases from April to June, peaking in May. The maximum concentration of aerosols over the southern TP occurs in July. Aerosols appear to be more easily transported over the main body of the TP across the northeastern edge rather than the southern edge. This is may be because the altitude is much lower at the northeastern edge than that of the Himalayas located along the southern edge of the TP. Three-dimensional distributions of dust, polluted dust, polluted continental and smoke are also investigated based on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Dust is found to be the most prominent aerosol type on the TP, and other types of aerosols affect the atmospheric environment slightly. A natural boundary seems to extend to an altitude of 6–8 km a.s.l., which may act as a dividing line of higher dust occurrence in the northern TP and lower dust occurrence in the southern TP, especially in spring and summer. This boundary appears around 33–35° N in the middle of the plateau, and it is possibly associated with the high altitude terrain in the same geographic location. Comparisons of CALIPSO and MISR data show that this natural boundary extending to upper troposphere is consistent with the spatial pattern of aerosol loading. The whole TP blocks the atmospheric aerosols transported from surrounding regions, and the extreme high mountains on the TP also cause an obstruction to the transport of aerosols. The aerosol distribution patterns are primarily driven by atmospheric circulation. Northerly winds prevail above the TP in spring, which also facilitates the transport of aerosols from the Tarim Basin and Qaidam Basin to the main body of the TP. Nevertheless, aerosols above the TP can originate from both the northern and southern sides of the TP during summer.

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Aerosol optical depth (AOD): spatial and temporal variations and association with meteorological covariates in Taklimakan desert, China

PeerJ ◽

10.7717/peerj.10542 ◽

2021 ◽

Vol 9 ◽

pp. e10542

Author(s):

Jinglong Li ◽

Xiangyu Ge ◽

Qing He ◽

Alim Abbas

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Environmental Variables ◽

Vegetation Index ◽

Meteorological Factors ◽

Meteorological Data ◽

Detection Methods ◽

Taklimakan Desert ◽

The Taklimakan Desert ◽

Modis Aod

Aerosol optical depth (AOD) is a key parameter that reflects aerosol characteristics. However, research on the AOD of dust aerosols and various environmental variables is scarce. Therefore, we conducted in-depth studies on the distributions and variations of AOD in the Taklimakan Desert and its margins, China. We examined the correlation characteristics between AOD and meteorological factors combined with satellite remote sensing detection methods using MCD19A2-MODIS AOD products (from 2000, 2005, 2010, and 2015), MOD13Q1-MODIS normalized difference vegetation index products, and meteorological data. We analyzed the temporal and spatial distributions of AOD, periodic change trends, and important impacts of meteorological factors on AOD in the Taklimakan Desert and its margins. To explore the relationships between desert aerosols and meteorological factors, a random forest model was used along with environmental variables to predict AOD and rank factor contributions. Results indicated that the monthly average AOD exhibited a clear unimodal curve that reached its maximum in April. The AOD values followed the order spring (0.28) > summer (0.27) > autumn (0.18) > winter (0.17). This seasonality is clear and can be related to the frequent sandstorms occurring in spring and early summer. Interannual AOD showed a gradually increasing trend to 2010 then large changes to 2015. AOD tends to increase from south to north. Based on the general trend, the maximum value of AOD is more dispersed and its low-value area is always stable. The climatic index that has the most significant effect on AOD is relative humidity.

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The regional distribution characteristics of aerosol optical depth over the Tibetan Plateau

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-12065-2015 ◽

2015 ◽

Vol 15 (20) ◽

pp. 12065-12078 ◽

Cited By ~ 31

Author(s):

C. Xu ◽

Y. M. Ma ◽

C. You ◽

Z. K. Zhu

Keyword(s):

Tibetan Plateau ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Qaidam Basin ◽

Regional Distribution ◽

Atmospheric Environment ◽

Main Body ◽

The Tibetan Plateau ◽

Variation Patterns ◽

Northern Edge

Abstract. The Tibetan Plateau (TP) is representative of typical clean atmospheric conditions. Aerosol optical depth (AOD) retrieved by the Multi-angle Imaging SpectroRadiometer (MISR) is higher over Qaidam Basin than the rest of the TP throughout the year. Different monthly variation patterns of AOD are observed over the southern and northern TP, whereby the aerosol load is usually higher in the northern TP than in the southern part. The aerosol load over the northern part increases from April to June, peaking in May. The maximum concentration of aerosols over the southern TP occurs in July. Aerosols appear to be more easily transported to the main body of the TP across the northern edge rather than the southern edge. This is maybe partly because the altitude is lower at the northern edge than that of the Himalayas located along the southern edge of the TP. Three-dimensional distributions of dust, polluted dust, polluted continental aerosol and smoke are also investigated, based on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Dust is found to be the most prominent aerosol type on the TP, and other types of aerosols affect the atmospheric environment slightly. A dividing line of higher dust occurrence in the northern TP and lower dust occurrence in the southern TP can be observed clearly at an altitude of 6–8 km above sea level, especially in spring and summer. This demarcation appears around 33–35° N in the middle of the plateau, and it is possibly associated with the high-altitude terrain in the same geographic location. Comparisons of CALIPSO and MISR data show that the vertical dust occurrences are consistent with the spatial patterns of AOD. The different seasonal variation patterns between the northern and southern TP are primarily driven by atmospheric circulation, and are also related to the emission characteristics over the surrounding regions.

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Validation of aerosol optical depth and climatology of aerosol vertical distribution in the Taklimakan Desert

Atmospheric Pollution Research ◽

10.5094/apr.2015.028 ◽

2015 ◽

Vol 6 (2) ◽

pp. 239-244 ◽

Cited By ~ 12

Author(s):

Xuemei Zong ◽

Xiangao Xia ◽

Huizheng Che

Keyword(s):

Vertical Distribution ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Taklimakan Desert ◽

The Taklimakan Desert

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Spatiotemporal variation of aerosol and potential long-range transport impact over the Tibetan Plateau, China

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-14637-2019 ◽

2019 ◽

Vol 19 (23) ◽

pp. 14637-14656 ◽

Cited By ~ 6

Author(s):

Jun Zhu ◽

Xiangao Xia ◽

Huizheng Che ◽

Jun Wang ◽

Zhiyuan Cong ◽

...

Keyword(s):

Tibetan Plateau ◽

South Asia ◽

Long Range ◽

Long Range Transport ◽

Back Trajectory ◽

Taklimakan Desert ◽

The Tibetan Plateau ◽

The Taklimakan Desert ◽

Aerosol Pollution ◽

Range Transport

Abstract. The long-term temporal–spatial variations in the aerosol optical properties over the Tibetan Plateau (TP) and the potential long-range transport from surrounding areas to the TP were analyzed in this work, by using multiple years of sun photometer measurements (CE318) at five stations in the TP, satellite aerosol products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), back-trajectory analysis from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) and model simulations from the Goddard Earth Observing System (GEOS)-Chem chemistry transport model. The results from the ground-based observations showed that the annual aerosol optical depth (AOD) at 440 nm at most TP sites increased in recent decades with trends of 0.001±0.003 yr−1 at Lhasa, 0.013±0.003 yr−1 at Mt_WLG, 0.002±0.002 yr−1 at NAM_CO and 0.000±0.002 yr−1 at QOMS_CAS. The increasing trend was also found for the aerosol extinction Ångström exponent (EAE) at most sites with the exception of the Mt_WLG site. Spatially, the AOD at 550 nm observed from MODIS showed negative trends at the northwest edge close to the Taklimakan Desert and to the east of the Qaidam Basin and slightly positive trends in most of the other areas of the TP. Different aerosol types and sources contributed to a polluted day (with CE318 AOD at 440 nm > 0.4) at the five sites on the TP: dust was the dominant aerosol type in Lhasa, Mt_WLG and Muztagh with sources in the Taklimakan Desert, but fine-aerosol pollution was dominant at NAM_CO and QOMS_CAS with transport from South Asia. A case of aerosol pollution at Lhasa, NAM_CO and QOMS_CAS during 28 April–3 May 2016 revealed that the smoke aerosols from South Asia were lifted up to 10 km and transported to the TP, while the dust from the Taklimakan Desert could climb the north slope of the TP and then be transported to the central TP. The long-range transport of aerosol thereby seriously impacted the aerosol loading over the TP.

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Modeling study on the transport of summer dust and anthropogenic aerosols over the Tibetan Plateau

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-12581-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 12581-12594 ◽

Cited By ~ 34

Author(s):

Y. Liu ◽

Y. Sato ◽

R. Jia ◽

Y. Xie ◽

J. Huang ◽

...

Keyword(s):

Tibetan Plateau ◽

Radiation Transport ◽

Eastern China ◽

Taklimakan Desert ◽

The Tibetan Plateau ◽

Northern Slope ◽

Southern Slope ◽

Anthropogenic Aerosols ◽

Anthropogenic Aerosol ◽

Dust Aerosols

Abstract. The Tibetan Plateau (TP) is located at the juncture of several important natural and anthropogenic aerosol sources. Satellites have observed substantial dust and anthropogenic aerosols in the atmosphere during summer over the TP. These aerosols have distinct effects on the earth's energy balance, microphysical cloud properties, and precipitation rates. To investigate the transport of summer dust and anthropogenic aerosols over the TP, we combined the Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS) with a non-hydrostatic regional model (NHM). The model simulation shows heavily loaded dust aerosols over the northern slope and anthropogenic aerosols over the southern slope and the east of the TP. The dust aerosols are primarily mobilized around the Taklimakan Desert, where a portion of the aerosols are transported eastward due to the northwesterly current; simultaneously, a portion of the particles are transported southward when a second northwesterly current becomes northeasterly because of the topographic blocking of the northern slope of the TP. Because of the strong upward current, dust plumes can extend upward to approximately 7–8 km a.s.l. over the northern slope of the TP. When a dust event occurs, anthropogenic aerosols that entrained into the southwesterly current via the Indian summer monsoon are transported from India to the southern slope of the TP. Simultaneously, a large amount of anthropogenic aerosol is also transported from eastern China to the east of the TP by easterly winds. An investigation on the transport of dust and anthropogenic aerosols over the plateau may provide the basis for determining aerosol impacts on summer monsoons and climate systems.

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Modeling study on the transport of summer dust and anthropogenic aerosols over the Tibetan Plateau

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-15005-2015 ◽

2015 ◽

Vol 15 (10) ◽

pp. 15005-15037 ◽

Cited By ~ 2

Author(s):

Y. Liu ◽

Y. Sato ◽

R. Jia ◽

Y. Xie ◽

J. Huang ◽

...

Keyword(s):

Tibetan Plateau ◽

Radiation Transport ◽

Model Simulation ◽

Eastern China ◽

Taklimakan Desert ◽

The Tibetan Plateau ◽

Northern Slope ◽

Southern Slope ◽

Anthropogenic Aerosols ◽

Dust Aerosols

Abstract. The Tibetan Plateau (TP) is located at the juncture of several important natural and anthropogenic aerosol sources. Satellites have observed substantial dust and anthropogenic aerosols in the atmosphere during summer over the TP. These aerosols have distinct effects on the earth's energy balance, microphysical cloud properties, and precipitation rates. To investigate the transport of summer dust and anthropogenic aerosols over the TP, we combined the Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS) with a non-hydrostatic regional model (NHM). The model simulation shows heavily loaded dust aerosols over the northern slope and anthropogenic aerosols over the southern slope and to the east of the TP. The dust aerosols are primarily mobilized around the Taklimakan Desert, where a portion of the aerosols are transported eastward due to the northwesterly current; simultaneously, a portion of the particles are transported northward when a second northwesterly current becomes northeasterly because of the topographic blocking of the northern slope of the TP. Because of the strong upward current, dust plumes can extend upward to approximately 7–8 km a.s.l. over the northern slope of the TP. When a dust event occurs, anthropogenic aerosols that entrain into the southwesterly current via the Indian summer monsoon are transported from India to the southern slope of the TP. Simultaneously, a large amount of anthropogenic aerosols is also transported from eastern China to east of the TP by easterly winds. An investigation on the transport of dust and anthropogenic aerosols over the plateau may provide the basis for determining aerosol impacts on summer monsoons and climate systems.

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Long-term aerosol optical depth datasets over China retrieved from satellite data

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-6643-2011 ◽

2011 ◽

Vol 4 (6) ◽

pp. 6643-6678 ◽

Cited By ~ 7

Author(s):

Y. Xue ◽

H. Xu ◽

Y. Li ◽

L. Yang ◽

L. Mei ◽

...

Keyword(s):

Aerosol Optical Depth ◽

Optical Depth ◽

Dust Storms ◽

The Tibetan Plateau ◽

Hysplit Model ◽

The North ◽

Moderate Resolution ◽

Dust Weather ◽

Moderate Resolution Imaging Spectroradiometer

Abstract. Nine years of daily aerosol optical depth (AOD) measurements have been derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data using the Synergetic Retrieval of Aerosol Properties (SRAP) method over China for the period from August 2002 to August 2011, comprising AODs at 470, 550, and 660 nm. Then, the variation over China over the nine years was determined from the derived AOD data. Preliminary daily results show the agreement between the Aerosol Robotic Network (AERONET) AOD data and the derived AOD data. From 1219 daily collocations, representing mutually cloud-free conditions, we find that more than 54% of SRAP-MODIS retrieved AOD values comparing with AERONET-observed values within an expected error envelop of 20%. From 222 monthly averaged collocations, representing mutually cloud-free conditions, we find that more than 63% of SRAP-MODIS retrieved AOD values comparing with AERONET-observed values within an expected error envelop of 15% and more than 70% within an expected error envelop of 20%. In addition, the long-term SRAP AOD dataset has been implemented in analysing case studies involving dust storms, haze and the characteristics of AOD variation over China over the past nine years. It was found that areas in China with high AOD values generally appear in the Inner Mongolia, the North China Plain, Tarim Basin, the Sichuan Basin, the Tibetan Plateau and the middle and lower reaches of the Yangtze River and area with low AOD values generally appear in the Fujian Province, the Yungui Plateau, and northeast plain. The seasonal averaged AOD results indicate that AOD values generally reach their maximum in spring and their minimum in winter. The yearly mean and monthly mean SRAP AOD were also used to study the spatial and temporal aerosol distributions over China. The results indicate that the AOD over China exhibited no obvious change. Monthly averaged AOD in August in Beijing experienced one decreasing processes from 2006 to 2010, especially after 2007. The monthly mean AOD decreased from 0.46 in 2007 to 0.29 in 2010. SRAP AODs were used to study one haze case and dust case. Combining AOD data from the SRAP AOD dataset and HYSPLIT model can forecast the transport of haze. SRAP AOD data are also sensitive enough to reflect the occurrence and intensity of dust weather. Thus, the SRAP AOD dataset can be used to precisely reflect the spatial distribution, concentration distribution and transmission path of dust.

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Elevated large-scale dust veil originated in the Taklimakan Desert: intercontinental transport and 3-dimensional structure captured by CALIPSO and regional and global models

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-14453-2009 ◽

2009 ◽

Vol 9 (4) ◽

pp. 14453-14481 ◽

Cited By ~ 1

Author(s):

K. Yumimoto ◽

K. Eguchi ◽

I. Uno ◽

T. Takemura ◽

Z. Liu ◽

...

Keyword(s):

Transport Model ◽

Asia Pacific ◽

Dust Particles ◽

Taklimakan Desert ◽

The Tibetan Plateau ◽

Free Troposphere ◽

The Taklimakan Desert ◽

The Pacific ◽

Blowing Up ◽

Intercontinental Transport

Abstract. An intense dust storm occurred during 19–20 May 2007 over the Taklimakan Desert in northwestern China. In the following days, the space-borne lidar CALIOP tracked an optically thin, highly elevated, horizontally extensive dust veil that was transported intercontinentally over the eastern Asia, Pacific Ocean, North America, and Atlantic Ocean. A global aerosol transport model (SPRINTARS) also simulated the dust veil quite well and provided a 3-D view of the dust intercontinental transport. The SPRINTARS simulation revealed that the dust veil travels at 4–10 km altitudes with a thickness of 1–4 km along the isentropic surface between 310 K and 340 K. The transport speed is about 1500 km/d. The estimated dust amounts exported to the Pacific is 30.8 Gg, of which 65% is deposited in the Pacific and 18% is transported to the North Atlantic. These results imply that the dust veil can fertilize the open oceans, provide background dust to the atmosphere remote from the sources. The entrainment mechanism that injects dust particles into the free atmosphere is important for understanding the formation of the dust veil and the subsequent long-range transport. We used a regional dust transport model (RC4) to analyze the dust emission and entrainment over the source region. The RC4 analysis revealed that strong northeasterly surface winds associated with a low pressure invade into the Taklimakan Desert through the east side corridor and form a strong up-slope wind along the high and steep mountainside of the Tibetan Plateau, blowing up large amounts of dust into the air. The updraft further brings the lofted dust particles up to the free troposphere (about 9 km MSL) where the westerly generally blows. The peculiar terrain surrounding the Taklimakan Desert plays the key role in the entrainment of dust to the free troposphere to form the dust veil.

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