Plateau Meteorology

Current Issue

28 April 2021, Volume 40 Issue 2   
  • Response of Thermal-Moisture Condition within Active Layer in the Hinterland of the Qinghai-Xizang Plateau to Climate Change
  • Hongliang XU;Juan CHANG;Linmao GUO;Wenjun SUN
  • 2021 Vol. 40 (2): 229-243.  DOI:10.7522/j.issn.1000-0534.2020.00071
  • Abstract ( ) HTML ( ) PDF (3993KB) ( )
  • As the energy-water exchange channel between permafrost-atmosphere system， the thermal-moisture conditions of the active layer are the main factors that control the hydrological cycle and surface energy balance， and directly affect the ecological environment， hydrological processes and stability of the permafrost in cold regions.The temperature and moisture contents within the active layer at Fenghuoshan station were simulated by one-dimensional water-heat coupling model CoupModel.The simulation efficiency parameters showed that the simulation results well reflected the thermal-moisture conditions of the active layer of permafrost in the study area.Based on the verified model， a variety of different climate change scenarios were set to analyze the response of the thermal-moisture conditions in the active layer to global climate change.Results showed that： （1） There was a positive correlation between soil temperature and air temperature， and the average temperature of active layer increased by about 0.78 ℃ for every 1 ℃ increment of air temperature， but the increment of soil temperature decreased as the soil depth increased； （2） The rising air temperature caused changes in the process of freezing and thawing of the active layer， and the impact by the latter is significantly greater than the former； （3） As the temperature rises， the soil water content at each depth of the active layer increased， and the increment increased with the increase of soil depth； （4） During the complete melted period， the increase in precipitation reduced the temperature of the shallow soil， but increased the temperature of the deep soil， while the temperature of each soil layer during the complete frozen period increased with the increase in precipitation； （5） The increase in precipitation caused an increase in the water content of the active layer， with the most obvious change in soil water content during the complete melted period.Therefore， climate warming and wetting will have a greater impact on the soil temperature and moisture of the active layer and the freezing-thawing cycles process in the permafrost regions of the Qinghai-Xizang Plateau， which may not be conducive to the development of frozen soil.
  • The Research on Characteristics of Dry-Wet Abrupt Alternation and the Response with Urbanization in Kunming of Yunnan Plateau
  • Ping HE;Pan WANG;Jinxiao LI;Shuhua LIU
  • 2021 Vol. 40 (2): 272-280.  DOI:10.7522/j.issn.1000-0534.2020.00018
  • Abstract ( ) HTML ( ) PDF (3331KB) ( )
  • Based on the daily precipitation data of Kunming from 1965 to 2016， the index of the long-term drought-flood abrupt alternations index （LDFAI） in flood season （from May to October）， short-term drought-flood abrupt alternations index （SDFAI） and the intensity of drought-flood abrupt alternations are calculated in this study.The characteristics of the drought-flood abrupt alternations in Kunming， and the correlation between the characteristics of drought-flood abrupt alternations and urbanization are analyzed by using the methods which include the wavelet analysis， Mann-Kendall （M-K） mutation test， grey correlation degree and other methods.The results indicate that the LDFAI shows the declining trend （-0.066 per 10 years） from 1965 to 2016， which means the decrement of drought-to-flood events but the increasement of flood-to-drought events in Kunming.Besides， LDFAI shows two mutation points in Kunming， but they are not significant.There is an 18-year main period of LDFAI in Kunming.On the other hand， according to the results of SDFAI， there is an increasement of drought-to-flood events， but a decrement of flood-to-drought events from May to July and from August to September.However， the opposite results are appeared from July to August and from September to October in Kunming.According to the correlation between the drought-flood abrupt alternations and urbanization， the six factors of urbanization index have effect of varying degrees on the drought-flood abrupt alternations at the resolution ratio of 0.5， All the correlation degree indexes are above 0.6， the urbanization index is significantly related to the drought-flood abrupt alternation.The most significant factors are smoke and dust emission， while the least important one is the total output value of non-agricultural economy， and their correlation coefficients are 0.909 and 0.630 respectively.
  • Vegetation Changes and Its Response to Climate Change in China Since 2000
  • Qianqian ZHAO;Jingpeng ZHANG;Tianbao ZHAO;Jianhua LI
  • 2021 Vol. 40 (2): 292-301.  DOI:10.7522/j.issn.1000-0534.2020.00025
  • Abstract ( ) HTML ( ) PDF (7023KB) ( )
  • Climate change is the main driving factor of vegetation change.It is of great significance to study the vegetation change and its response to climate change in China under the background of global warming for the country to carry out major ecological restoration assessment and future vegetation protection policy formulation.Using MODIS vegetation index NDVI dataset during 2000-2016 and statistical analysis method， this paper systematically analyzes the regional vegetation change and its response to climate change in China since 2000 from the aspects of average state， linear trend， time series， correlation， etc.The results show that the spatial distribution of climate mean of NDVI in China is decreasing from southeast to northwest， and vegetation index in the East is significantly larger due to the influence of precipitation during the growing season.NDVI shows an increasing trend in most areas of China， especially in humid and semi-humid areas， the growth rate of NDVI reaches 0.037·（10a）-1， while in arid and semi-arid areas， the change of NDVI is relatively small.In the southeast coastal areas， eastern northeast area， and northern Qinghai Tibet Plateau， NDVI has a significant positive correlation with the temperature， with the rising speed of 0.02 ℃-1， while NDVI has a weak negative correlation with the temperature in the south of Qinghai-Tibetan Plateau， with the decreasing speed of more than -0.015 ℃-1.Similarly， NDVI is positively correlated with precipitation in Sichuan Basin and Inner Mongolia， and NDVI increases by more than 0.03 for every 100 mm increase in precipitation， NDVI is weakly negatively correlated with precipitation in Qinghai-Tibetan Plateau， Tarim Basin and other areas， that is， the change of precipitation has no obvious impact on NDVI.For the NDVI variation associating to climate change， the response of vegetation change to climate driving factor also shows obvious regional difference.In the southeast coast of China， the east of Yunnan Guizhou Plateau， Sichuan Basin and other southern areas， as well as the middle and lower reaches of the Yellow River， the east of northeast and other parts of the region， the change of NDVI is the most sensitive to temperature.In the most arid and semi-arid areas of northern China， the change of NDVI has very significant response to precipitation.In general， the precipitation is the driver factor for most of southern China while the air temperature is the dominator for most of northern China.
  • Impact of Mongolian High and Polar Vortex Mid-term Synoptic Activity on Continuous Blizzard in North Xinjiang in 2010
  • Liyun MA;Jian RAO;Xiaojuan SUN;Suxing ZHU;Chunhua SHI;Changsheng CHEN;Dong GUO
  • 2021 Vol. 40 (2): 302-313.  DOI:10.7522/j.issn.1000-0534.2020.00040
  • Abstract ( ) HTML ( ) PDF (7008KB) ( )
  • Based on the NCEP1 reanalysis of daily， monthly geopotential height， sea level pressure， wind， temperature， relative humidity data and daily precipitation data of China's surface climate data multi-day data set V3.0（SURF_CLI_CHN_MUL_DAY）， the mid-term synoptic process characteristics of the 5 continuous snowfall episodes in northern Xinjiang province during January to February in 2010 and the influences of the surface Mongolian high pressure and the upper troposphere polar vortex on them are analyzed.The results show that the strong and continuous outbreak of Mongolian high pressure under abundant water vapor conditions is an important cause of extreme snowfall in 2010.In this year， the average intensity of Mongolian high pressure was the strongest in the historical data.During this continuous snowfall processes， there were 5 times north-south direction movements of the surface Mongolian high pressure’s center and 5 times oscillations of its intensity and area.In addition， before each snowfall and cooling process， the center of Mongolian high pressure at surface moved southward， and the area of Mongolian high pressure expanded and the intensity of Mongolian high pressure increased.Lead/lag correlation between the latitude of the surface Mongolian high pressure center and the daily average temperature of Xinjiang area is significant， and the number of days of leading is 1~3 days.Lead/lag correlation between the intensity of the surface Mongolian high pressure and the daily average temperature of Xinjiang area is significant， the number of days of leading is 1~3 days.Lead/lag correlation between the area of the surface Mongolian high pressure and the daily average temperature of Xinjiang area is significant as well， and the number of days of leading is 1~4 days.The article also selects the years of abnormal large snowfall in the historical records to study the lead-lag correlation between the upper troposphere polar vortex circulation index and the surface Mongolian high pressure circulation index， study found that the characteristics of the multi-year synthesis results are basically similar to the exceptional year 2010.The synthesis results further verify the correlation between the surface Mongolian high pressure and the upper troposphere polar vortex， that is， the enhancement of the intensity and the northward movement of the center of polar vortex at the upper troposphere in the early stage， which was conducive to the enhancement of the intensity， the expansion of the area and the northward movement of the center of the Mongolian high pressure at surface in the later stage.
  • Impact of Flow around and Flow over in Sudden Rainstorm on Mountains
  • Yan JIN;Guoping LI
  • 2021 Vol. 40 (2): 314-323.  DOI:10.7522/j.issn.1000-0534.2020.00041
  • Abstract ( ) HTML ( ) PDF (7806KB) ( )
  • Using ERA5 reanalysis data and CMORPH data， for a sudden rainstorm that occurred in the southwestern Sichuan Basin in China from May 21 to 22， 2018， first the correlation analysis of its rainfall intensity and weather profile was carried out， and then the flow field was decomposed into flow around and flow over components through the flows around and over equations， further investigating the influence of flow around and flow over caused by terrain on rainstorm.The results indicate that due to the combined effects of the northwest airflow guiding the cold air southward and southwest vortex eastward， a heavy rainfall process occurred in the mountainous area in the southwest of the Sichuan Basin.This precipitation had a wide range， high intensity and concentrated precipitation time， which was a typical sudden mountain rainstorm event.Due to the blocking effect of the terrain， the airflow from the northeast direction rotates， generating the flow around and forming a local vortex in the basin.At the same time， the terrain height difference between the basin and the mountain forced the over-the-air flow to generate the flow over， resulting in increased vertical ascent.Under the combined effects of flow around and flow over， it provided favorable flow field conditions for the occurrence and development of this sudden rainstorm.Further analysis showed that the flow over component in the terrain area was slightly larger than the flow around component， that is， the response of the airflow to terrain at such altitudes as mountainous terrain was dominated by flow over and secondary flow around， and the vertical ascending motion caused by flow over was closely related to the distribution of rain belts.
  • Land Monsoon and Non-monsoon Regions under Climate Change Comparison of Extreme Precipitation Characteristics
  • Jing HE;Guangzhou FAN;Yongli ZHANG;Xin LAI
  • 2021 Vol. 40 (2): 324-332.  DOI:10.7522/j.issn.1000-0534.2020.00077
  • Abstract ( ) HTML ( ) PDF (7115KB) ( )
  • This article uses the monthly precipitation and monthly daily average temperature data from the monthly average surface climate element data set （CRU TS 4.02）， and uses linear trend analysis， moving average and correlation analysis methods to study the background of climate change from 1901 to 2017 The characteristics of extreme precipitation in the global terrestrial monsoon and non-monsoon regions.The results show that the frequency distribution of extreme precipitation in the Asian monsoon region where China is located is relatively stable， and only large-scale and small-value areas appear during the warming slowing period； the non-monsoon area shows a polarization in the frequency distribution of extreme precipitation during the Sharply accelerated warming period.The small value area and the large value area coexist in the monsoon area， which is not easy to occur.The average change of extreme precipitation frequency in monsoon and non-monsoon regions basically tends to be the same， and only differs during periods of accelerated warming.Monsoon and non-monsoon extreme precipitation frequency changes in the proportion of grid points in the small value area tend to be consistent， and only differ in the two accelerated warming periods.For the large value area， excluding the periods of 1921 -1949 and 1950 -1972， the monsoon area is larger.The proportion of grid points in the value area is lower than that in the non-monsoon area.The distribution of extreme precipitation in monsoon and non-monsoon regions is relatively less affected by climate change， but no matter which period of cold or warm， the extreme precipitation in monsoon regions is much higher than that in non-monsoon regions.The correlation between extreme precipitation frequency and temperature in non-monsoon regions is better than that in monsoon regions.When temperature trends are superimposed， most areas of mid-to-high latitudes are positively correlated.After detrending， the correlation weakens.
  • Numerical Studies on Effects by Different Initial Fields on a Rainstorm in Northwest China
  • Zifei HAN;Xiao LONG;Siyi WANG;Qian WEI;Xiaoyan CHEN
  • 2021 Vol. 40 (2): 333-342.  DOI:10.7522/j.issn.1000-0534.2020.00017
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  • Effects of different initial fields from global data such as GRAPES_GFS， FNL and ERA-interim on a rainstorm process which occurred in the Northwest of China from 6 to 7 August 2017 were studied with Meso-scale model WRF V3.8.1 Synoptic analyses show that the formation and evolution of the rainstorm was caused by the strengthen of the South Asia High associated with the upper jet at 200 hPa， westwards extending and northwards moving of the subtropical high as well as development of the plateau trough at 500 hPa and low-level shear line at 700 hPa.Comparative analyses indicate that only easterly low-level jet at 700 hPa was appeared in the GRAPES_GFS data among three kinds of data， which may be the mainly synoptic system for difference of simulated distribution of precipitation with different initial fields.There are some differences at middle and low levels of troposphere in simulated results with three initial fields， which are not obvious at upper levels.A deep trough was appeared in the southeast part of Gansu province in simulated output by initial field from GRAPES-GFS data at 500 hPa， which was a closed low system by initial field from FNL data， while no obvious low systems by initial field from ERA-interim data； At level of 700 hPa， development of easterly low-level jet stream and cyclonic circulation systems can be simulated with three initial fields and there are slightly difference in intensity of simulated systems.According to the distribution of precipitation， simulated results have obvious differences by three initial fields， the location of precipitation center and the regional average precipitation rate simulated by initial field from FNL data were the best among three different initial fields， according to evaluation indexes such as TS， FAR and POD， initial filed from GRAPES_GFS data was the best but the rate of vacancy forecast of rainfall below 20 mm level was relatively larger； Simulated results with initial field from ERA-interim data were the worst in this case.
  • Variation Characteristics of the Date of First Frost and Last Frost and the Frost-Free Period in North China in Recent 58 Years
  • Wenhui JIAO;Bo ZHANG;Bin MA;Yanqiang CUI;Liting XING;Xiaodan WANG;Hao HUANG
  • 2021 Vol. 40 (2): 343-352.  DOI:10.7522/j.issn.1000-0534.2020.00085
  • Abstract ( ) HTML ( ) PDF (5811KB) ( )
  • Frost will seriously affect normal agricultural activities.It is of great significance to know and grasp the changing characteristics of the first frost and last frost and the frost-free period to guide agricultural production practices， improve the prevention and early warning capabilities of frost disasters.Based on the ground 0 cm daily minimum temperature and average temperature data of 90 stations （1961 -2018） in over North China， using the methods of linear regression， inverse distance weighted， Mann-Kendal test and cumulative anomaly to analyze the variation characteristics of the first frost and last frost and the frost-free period in North China.The results show that： （1） In terms of time changes， the first frost date， the last frost date and the frost-free period showing the significant trends in delay， advance and extension， respectively， which gradually became obvious from the 1980s； The changing characteristics of the frost reflects the climate warming.（2） Along with the decrease of the latitude and the altitude， the first frost date， the last frost date and the frost-free period show trends of delay， advance and extension， respectively.And if the average temperature at the station raised significantly， the rate of delay， advance and extension of the initial， final and frost-free periods is also significant； The first frost date， the last frost date and the frost-free period in the mountain are earlier， later and shorter than those in the plain， respectively.（3） The mutation years of first frost date， last frost date and the frost-free period were 1986， 1995 and 1995， respectively.And the mutation years of the frost in the three sub-regions all occurred in the 1980s and 1990s.（4） Based on different climatic reference periods and different decadal， The locations of the contour lines of the first frost date， the last frost date and the frost-free period all gradually moving northward.（5） The changes in the predicted frost period are roughly the delay of the first frost date， the advance of the last frost date， and the prolonged frost-free period.But there is a slight difference in the magnitude of the change with the descending order of frost-free period， last frost date and first frost date.
  • Analysis on Effect of Tropical Indian Ocean Dipole Inter-Annual Oscillation on Annual Variation of Runoff in the Upper Reaches of Yangtze River
  • Yishu PANG;Ningsheng QIN;Yu LUO;Chunxue WANG;Bin ZHOU
  • 2021 Vol. 40 (2): 353-366.  DOI:10.7522/j.issn.1000-0534.2020.00045
  • Abstract ( ) HTML ( ) PDF (9191KB) ( )
  • In this paper， the influence of Tropical Indian Ocean Dipole （TIOD） oscillation in autumn on the annual runoff in the upper reaches of the Yangtze river in the following year and the corresponding physical mechanism were analyzed by means of interannual increment， wavelet analysis and regression analysis.The results show that both the autumn TIOD and annual runoff of the upper Yangtze River have significant interannual oscillation characteristics， especially before the 1980s and after the 1990s.Their hysteresis correlation coefficient is 0.42， passing the significance test of 99.9%.In other words， autumn TIOD was strengthened （weakened） compared with the previous year， which is conducive to the increase （decrease） of runoff in the upper reaches of the Yangtze river in the next year.Such a relationship can be realized through the modulation of autumn TIOD on precipitation， especially the summer precipitation.When TIOD is strengthened in autumn， the SST of the equatorial Indian Ocean shows an east-west "-+" distribution， in which the warmer zone extends to 20°N/S， and the colder zone stretches to the western Pacific Ocean.An enhanced Walker circulation is stimulated over the equatorial Indian Ocean to the western Pacific Ocean， centered directly over the Indian Ocean.With the development of time， the warm Kelvin wave generates and propagates to the east， and the center of the warm and cold sea temperature difference in the Indian Ocean moves to the east.In the following summer， the warm SST center of the western Indian Ocean moves to the edge of the eastern Indian Ocean to the South China Sea， while the cold area retreats to date line.The enhanced Walker circulation over Indian Ocean disappeared while the westerly of its upper layer turns to easterly and links to enhanced climbing airflow near 105°E.At the same time， the Walker Cell over the east of 105°E is strengthened， of which the upper level is westerly and the region below 400 hPa is easterly airflow.With the Coupling of high- and low-level circulation and cooperation with the Coriolis force， the negative vorticity increases in the subtropical zone of Northern Hemisphere， which lead to a larger and stronger West Pacific Subtropical High and northward expansion of corresponding anomalous anticyclone accordingly.Southwest airflow around this circulation system strengthens the water vapor transportation from the South China Sea and Bay of Bengal to the whole upper reaches of the Yangtze River in summer.Water vapor convergence rises and the precipitation significantly is more， which affects the variation of annual runoff in the upper reaches of the Yangtze River.
  • Impact of Aerosol on the Summer Wind Speed at the Lower Layer in the Mid-Latitude of China
  • Xiaohong XU;Xing YU;Yannian ZHU;Jin DAI;Zipeng DONG
  • 2021 Vol. 40 (2): 367-373.  DOI:10.7522/j.issn.1000-0534.2020.00037
  • Abstract ( ) HTML ( ) PDF (3250KB) ( )
  • Based on the fact that the turning point of aerosol variation has occurred since 2012， two time series of climatological data were set by the period last to 2011 and that to 2018 from the available.The used data is daily of 14:00 （Beijing Time） in summer season last more than 40 years from selected unmigrated 133 meteorological stations.The annual variability of wind speed， temperature and sea-level pressure in the mid-latitude of China were analyzed and compared between two time series.Also the spatial distribution and annual variability of AOD were analyzed and were correlated with that of wind speed， temperature and pressure with the data of MODIS aerosol optical thickness （AOD） product from 2002 to 2018.The results show that： （1） AOD was small over the Qinghai-Xizang plateau （QXP）， and was large over the Qing-ba mountainous area and inland plain with increasing trend from 2002 to 2011 and turning decrease from 2002 to 2018， which suggests the effectiveness of air-pollution control after 2012.（2） Before 2012， the temperature increased in QXP and the western Qing-ba mountainous area， and declined in the eastern Qing-ba mountainous area and the inland plain and with maximum decreasing around 114°E.Compared with that of time series to 2018， the extent of temperature decrease and pressure increases lightly declined during AOD decreasing， which reflects the respondence of temperature and pressure to AOD.（3） The wind speed in summer was generally decreasing， especially in the inland plain with the largest annual reduction rate of -0.06~-0.02 m·s-1.Also the annual variability of wind speed was reverse to that of AOD distribution.It was shown that the decreasing extent of wind speed was modulated by declination of average AOD by the comparison of two time series， which suggests the sensitivity of wind speed to aerosol variation.
  • Characteristics of Surface-layer Turbulence Spectra in Xiaoxing’an Mountains
  • Pengfei SUN;Guangzhou FAN;Zhe QU;Xingguang LIU;Yinjun WANG;Chao YUAN
  • 2021 Vol. 40 (2): 374-383.  DOI:10.7522/j.issn.1000-0534.2020.00099
  • Abstract ( ) HTML ( ) PDF (2727KB) ( )
  • Based on the turbulence data obtained from eddy covariance system at the height of 50 m in Wuying over the Xiaoxing'an Mountains， the spectra and cospectra of turbulence under different atmospheric stability are analyzed.The results indicate that the peaks of the normalized spectra of velocity （u， v， w） moves to the high frequency with the increased of atmospheric stability.The characteristics of the normalized spectra of temperature （θ） and humidity （q） are similar to those of the velocity （u， v， w） spectra， but the spectral density curves are dispersed under different stability conditions.The normalized cospectra of the vertical wind component （w） and u-wind component （u） are similar to those of the spectra of velocity （u， v， w）， which are same as the normalized cospectra of the vertical wind component （w） and temperature （θ）.The normalized spectra of velocity （u， v， w） and temperature （θ） and humidity （q） follow the -2/3 law in the higher frequency.The normalized cospectra of uw and θw and qw do not completely follow the -4/3 law in the higher frequency， especially the slopes of fitting line for uw-cospectra is closer to -1.The peak wavelength of u-spectra is about 130~1820 m， and the spectra of w and θ and q are about 49~113 m， 149~260 m and 198~455 m， respectively.The peak wavelength of the cospectra of uw and θw and qw are about 228~455 m， 172~260 m and 172~346 m， respectively.The v-spectra conforms the local isotropy in the higher frequency， and the w-spectra does not satisfy the local isotropy， which may be attributed to the fragmentation of the vertical turbulent vortex in forest underlying surface.
  • A Study on Radar Echo Nowcasting Based on Convolutional Gated Recurrent Unit Neural Network
  • Xunlai CHEN;Jun LIU;Qunfeng ZHEN;Xutao LI;Jia LIU;Xiyang JI;Yuanzhao CHEN;Yunming YE
  • 2021 Vol. 40 (2): 411-423.  DOI:10.7522/j.issn.1000-0534.2020.00023
  • Abstract ( ) HTML ( ) PDF (12357KB) ( )
  • At present， the extrapolation forecast based on radar echoes is the mainstay of disaster weather 0~2 hours nowcasting.This paper proposes a convolutional gated recurrent unit neural network （ConvGRU） by using radar mosaics at 6 min intervals obtained from the radar images provided by 11 doppler radars in Guangdong Province from 2015 to 2018.Through the automatic learning of massive data， the inherent characteristics of the data and the contained physical laws can be discovered using the proposed network.A multi-loss function weighting and hierarchical weighting strategy are proposed.Based on the ConvGRU framework， a three-layer self-encoding model （Encoder-Decoder） is built for training to establish a radar echo prediction model which predicts radar echoes for 20 consecutive frames in the next 2 hours by 6 minutes.The results are compared with the operationally applied methods including tracking radar echoes by correlation （TREC）， optical flow， and particle filter using typical case analysis and long-term verification.All the subjective and objective evaluation results indicate that the proposed ConvGRU method shows better forecasting performance in severe convective weather systems in predicting radar echo position， intensity and shape than other methods.These results indicate that the deep learning method can better grasp the characteristics of the strong echo area， and predict the strong echo accurately to a certain extent by automatic learning of time-series radar echo data.For the long-term evaluation results， the ConvGRU method has higher critical success index （CSI） and probability of detection （POD） scores than those of the traditional TREC， optical flow and particle filtering methods， and has the lowest false alarm rate （FAR） scores among all methods， suggesting it could be widely used in operational applications.However， the deep learning-based method has the limitation of losing spatial detail information in radar echoes due to the up-sampling and down-sampling operators， and the prediction performance of stratiform cloud precipitation is relatively poor.
  • Variation and Source Analysis of Water-Soluble Ions in the Atmospheric Particles of Mogao Grottoes at Dunhuang
  • Xiaoju YANG;Fasi WU;Ruihong XU;Dongpeng HE;Guobin ZHANG;Shichang KANG;Chaoliu LI;Wanfu WANG
  • 2021 Vol. 40 (2): 436-447.  DOI:10.7522/j.issn.1000-0534.2020.00033
  • Abstract ( ) HTML ( ) PDF (5600KB) ( )
  • With the purpose of exploring the characteristics of atmospheric particulate pollution at the Mogao Grottoes， the samples of PM2.5 and PM10~2.5 were collected in Cave 16 and exterior environment of Cave 72 from April to December， 2014.The researcher conducted contrastive analysis on the variation and influence factors of the water-soluble ions in the samples， and studied their main sources by the approach of Principal Component Analysis （PCA）.The results are as follows： （1） The main wind direction at Mogao Grottoes area is south wind and the frequency of wind with sand is only 0.01%， which is unfavorable to the diffusion of pollutants.（2） The total concentration of water-soluble ions of PM2.5 and PM10~2.5 in the exterior environment of Cave 72 are 6.1±4.0 μg·m-3 and 12.2±9.1 μg·m-3， while in the interior environment of Cave 16 are 3.7±0.8 μg·m-3 and 7.5±1.6 μg·m-3.SO42-， Ca2+， NO3-， Na+， and Cl- are the main components of water-soluble ions.As for the proportion of water-soluble ions of PM2.5 and PM10~2.5 in the exterior environment， SO42-， NO3-， and Ca2+ together account for 79.24% and 76.81%.In the interior environment， the number is 80.61% and 77.74%.The Secondary ions originate mainly from stationary pollution sources.（3） The ratio of each ion concentration in PM2.5 and PM10~2.5 are 0.33~0.88 （outside the cave） and 0.25~0.94 （inside the cave）.9 water-soluble ions are different in terms of their concentration degrees in different particle sizes.Sand storms from March to May， rainfalls from July to September， straw burning in rural areas in November， and coal burning for heating in winter have some effects on water-soluble ions.The number of touristsinside the caves has certain correlation with NH4+ and NO3- from the perspective of PM2.5 （R2=0.27， 0.35）， and with NH4+ （R2=0.31） from PM10~2.5.（4） Owing to the sand and dust weathers， the concentration of Cl-， SO42-， Na+， K+ and Ca2+ increase in the PM2.5 and PM10-2.5 inside and outside the cave.The results indicate that micro-environment at the Mogao Grottoes is mainly influenced by the regional meteorological factors.Therefore， the caves should be closed during inclement weather.（5） The atmospheric environment at Mogao Grottoes area is alkaline.（6） The main resources causing the increase of PM2.5 and PM10~2.5 are crop burning in local areas， secondary pollution sources， sand and dust， and dried-out Daquan River.

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