The severe sandstorm process in Ulanqab,Inner Mongolia on March 15,2021 was analyzed and discussed from the aspects of weather facts,weather causes and dynamic diagnosis.The results show that the strong cold air in We...The severe sandstorm process in Ulanqab,Inner Mongolia on March 15,2021 was analyzed and discussed from the aspects of weather facts,weather causes and dynamic diagnosis.The results show that the strong cold air in West Siberia rapidly moved eastward,and the surface cold front moved eastward to Ulanqab with significant warming in the previous period,resulting in gale and sandstorm weather.This severe sandstorm process occurred in basically stable atmospheric stratification.During the strong sandstorm and extremely strong sandstorm process on March 15,the strong warming in the early period near the surface led to the surface thermal instability,and sand was generated by the upward movement of the Mongolian cyclone.Over the upper northwest air stream,barocline disturbance developed unsteadily,and the upper cold advection stimulated the secondary circulation of front perpendicular to the surface;the surface cyclone turned into strong cold front,and then strong sandstorm weather occurred in Ulanqab.展开更多
Based on the data of sandstorm at 11 stations in Ulanqab City from 1990 to 2021,the spatial and temporal variation characteristics of sand-storm weather were analyzed firstly,and then the conceptual models of cold fro...Based on the data of sandstorm at 11 stations in Ulanqab City from 1990 to 2021,the spatial and temporal variation characteristics of sand-storm weather were analyzed firstly,and then the conceptual models of cold front and Mongolian cyclone sandstorm were obtained by analyzing sandstorm cases.Finally,the forecast points of the two types of sandstorm weather were given to provide some scientific basis and reference for the prediction of local sandstorm weather in the future.展开更多
[Objectives]To explore the distribution characteristics of soil organic carbon in degraded forest land in the sandstorm area of Jingbian County,Shaanxi Province.[Methods]The distribution characteristics and abundance ...[Objectives]To explore the distribution characteristics of soil organic carbon in degraded forest land in the sandstorm area of Jingbian County,Shaanxi Province.[Methods]The distribution characteristics and abundance of 0-20 cm shallow soil organic carbon in 5 towns in the sandstorm area in the north of Jingbian County were studied by field sampling and indoor detection.[Results]The average soil organic carbon contents in Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town and Dongkeng Town were 2.93,3.21,2.53,2.54 and 4.08 g/kg,respectively,which were all lower than the national background value(31.00 g/kg).The coefficients of variation of soil organic carbon content in Hongdunjie Town,Huanghaojie Town and Dongkeng Town were 59.04%,35.97%and 47.55%,respectively,with higher coefficients of variation and larger differences in spatial distribution.The organic carbon content of Haizetan Town and Dongkeng Town was above the abundance,accounting for 70%and 50%,which were relatively rich,while the soil organic carbon content of Hongdunjie was relatively scarce.The average content of soil organic carbon in the sandstorm area was 3.03 g/kg,which was also lower than the national background value.The coefficient of variation was 46.53%,showing high coefficient of variation and large difference in spatial distribution.In addition,20.41%of the average content of soil organic carbon in the sandstorm area was in the deficient level,and 79.59%were in the medium or above level.[Conclusions]The study of distribution characteristics of soil organic carbon in degraded forest land in the sandstorm area of Jingbian County will better serve the precise management of soil resources.展开更多
In this paper,we present a tensor least square based model for sand/sandstorm removal in images.The main contributions of this paper are as follows.First,an important intrinsic natural feature of outdoor scenes free o...In this paper,we present a tensor least square based model for sand/sandstorm removal in images.The main contributions of this paper are as follows.First,an important intrinsic natural feature of outdoor scenes free of sand/sandstorm is found that the outlines in RGB channels are somewise similar,which discloses the physical validation using the tensor instead of the matrix.Second,a tensor least square optimization model is presented for the decomposition of edge-preserving base layers and details.This model not only decomposes the color image(taken as an inseparable indivisibility)in X,Y directions,but also in Z direction,which meets the statistical feature of natural scenes and can physically disclose the intrinsic color information.The model’s advantages are twofold:one is the decomposition of edgepreserving base layers and details that can be employed for contrast enhancement without artificial halos,and the other one is the color driving ability that makes the enhanced images as close to natural images as possible via the inherent color structure.Thirdly,the tensor least square optimization model based image enhancement scheme is discussed for the sandstorm weather images.Finally,the experiments and comparisons with the stateof-the-art methods on real degraded images under sandstorm weather are shown to verify our method’s efficiency.展开更多
Climate change influences both ecosystems and ecosystem services.The impacts of climate change on ecosystems and ecosystem services have been separately documented.However,it is less well known how ecosystem changes d...Climate change influences both ecosystems and ecosystem services.The impacts of climate change on ecosystems and ecosystem services have been separately documented.However,it is less well known how ecosystem changes driven by climate change will influence ecosystem services,especially in climate-sensitive regions.Here,we analyzed future climate trends between 2040 and 2100 under four Shared Socioeconomic Pathway(SSP) scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5) from the Coupled Model Intercomparison Project 6(CMIP6).We quantified their impacts on ecosystems patterns and on the ecosystem service of sandstorm prevention on the Qinghai-Tibet Plateau(QTP),one of the most climate-sensitive regions in the world,using Random Forest model(RF) and Revised Wind Erosion Equation(RWEQ).Strong warming(0.04℃/yr) and wetting(0.65 mm/yr) trends were projected from 2015 to 2100.Under these trends,there will be increased interspersion in the pattern of grassland and sparse vegetation with meadow and swamp vegetation,although their overall area will remain similar,while the areas of shrub and needleleaved forest classes will increase and move toward higher altitudes.Driven by the changes in ecosystem patterns caused by climate change indirectly,grassland will play an irreplaceable role in providing sandstorm prevention services,and sandstorm prevention services will increase gradually from 2040 to 2100(1.059-1.070 billion tons) on the QTP.However,some areas show a risk of deterioration in the future and these should be the focus of ecological rehabilitation.Our research helps to understand the cascading relationship among climate change,ecosystem patterns and ecosystem services,which provides important spatio-temporal information for future ecosystem service management.展开更多
Sandstorm is a frequently occurred disastrous weather in northern China. The increasing occurrence frequency recently, especially the much more frequently occurred sandstorms with high intensity in the spring of 2000 ...Sandstorm is a frequently occurred disastrous weather in northern China. The increasing occurrence frequency recently, especially the much more frequently occurred sandstorms with high intensity in the spring of 2000 have caused great loss to national economy. The combination of strong wind, exposed sandy soil on ground surface and unstable air current constitutes the necessary conditions for the sandstorms. However, the accelerated desertification process resulting from irrational human economic activities is responsible for the accelerated sandstorms. The effective measures to mitigate sandstorm lie in strengthening desertification control and eco-environmental protection.展开更多
Dominated by an arid and semiarid continental climate,the Beijing-Tianjin Sandstorm Source Region(BTSSR)is a typical ecologically fragile region with frequently occurring droughts.To provide information for regional v...Dominated by an arid and semiarid continental climate,the Beijing-Tianjin Sandstorm Source Region(BTSSR)is a typical ecologically fragile region with frequently occurring droughts.To provide information for regional vegetation protection and drought prevention,we assessed the relations between vegetation cover change(measured by the Normalized Difference Vegetation Index,NDVI)and the Standardized Precipitation Evapotranspiration Index(SPEI)at different time-scales,in different growth stages,in different subregions and for different vegetation types based on the Pearson's correlation coefficient in the BTSSR from 2000 to 2017.Results showed that 88.19%of the vegetated areas experienced increased NDVI in the growing season;48.3%of the vegetated areas experi-enced significantly increased NDVI(P<0.05)and were mainly in the south of the BTSSR.During the growing season,a wetter climate contributed to the increased vegetation cover from 2000 to 2017,and NDVI anomalies were closely related to SPEI.The maximum correlation coefficient in the growing season(Rmax)was significantly positive(P<0.05)in 97.84%of the total vegetated areas.In the vegetated areas with significantly positive Rmax,pixels with short time-scales(1-3 mon)accounted for the largest proportion(33.9%).The sensitivity of vegetation to the impact of drought rose first and then decreased in the growing season,with a peak in July.Compared with two subregions in the south,subregions in the north of the BTSSR were more sensitive to the impacts of drought variations,especially in the Xilingol Plateau and Wuzhumuqin Basin.All four major vegetation types were sensitive to the effects of drought variations,especially grasslands.The time-scales of the most impacting droughts varied with growth stages,regions,and vegetation types.These results can help us understand the relations between vegetation and droughts,which are important for ecological restoration and drought prevention.展开更多
Based on the observational data, NCEP 1°×1° reanalysis data and potential vorticity theory, the occurrence mechanism of a strong sandstorm occurring in Inner Mongolia during March 14-15 was studied. The...Based on the observational data, NCEP 1°×1° reanalysis data and potential vorticity theory, the occurrence mechanism of a strong sandstorm occurring in Inner Mongolia during March 14-15 was studied. The results show that the large potential vortex area in the upper troposphere moved eastward and downward, and a structure similar to a "funnel" appeared;the cyclone moved eastward and developed;the high potential vortex region always matched the region where the cyclone developed;the development of the cyclone was closely related to the cold air activity, and there was an obvious interaction between high-and low-altitude systems. The potential vorticity at 500 hPa had obvious significance for the influencing system of this sandstorm. The 0.5 PVU contour line can be used as the boundary of sandstorm weather area. On the potential temperature profile, the occurrence process of this sandstorm was the process of the expansion of cold air from high latitudes to low latitudes. When the high-value potential vorticity system slide along the isentropic surface, the lower vertical vorticity increased due to the increasing slope of the isentropic surface and the conservation of potential vorticity, leading to the development of the surface cyclone circulation and the enhancement of wind speed, and further causing the occurrence of this sandstorm.展开更多
The aim of the study is to classify the Sandstorms according to year seasons as well as their spatial variation in Saudi Arabia. Factor analysis has been used for data collection. Three factors have been presented: th...The aim of the study is to classify the Sandstorms according to year seasons as well as their spatial variation in Saudi Arabia. Factor analysis has been used for data collection. Three factors have been presented: the first factor related to Spring as a prime Season for Dust Sandstorms. Factor two shows that Samar months concern as ascend season for Sandstorms, while the Autumn Season comes as a third period for Dust Sandstorms. With regard to spatial variation, Al-Ahsa station came as the most closely related station in the spring season, followed by Hafr Elbatten, Jazan and Al-Jouf stations, while Jazan and Yenbo stations were the most connected stations in the summer season, Turaif is more closely related, to Fall season. By the end of the study several results and recommendations have been addressed.展开更多
The main causes of the heavysandstorms ravaging north Chinathis spring are abnormal climateand the encroachment ofdesertification, says a CAS reportreleased in Beijing on May 15.
The purpose of this present study is to investigate the frequency and variation of sandstorm in Minqin Oasis. Using daily observational data of sandstorm and other meteorologic data from 1954 to 2000, we have illumina...The purpose of this present study is to investigate the frequency and variation of sandstorm in Minqin Oasis. Using daily observational data of sandstorm and other meteorologic data from 1954 to 2000, we have illuminated the relationship between sandstorm, meteorological parameters and human activities. The results of the analysis show that the highest frequency of sandstorms occurrence and their duration mainly focus on March, April and May, especially in April. Most of sandstorms occur from midday to nightfall, but relative few appear from midnight to forenoon, which apparently correlates to the daily variations of atmospheric thermal stability within atmospheric boundary layer. Monthly mean and annual mean duration of sandstorms coincide well with the frequencies of sandstorm occurrence.展开更多
Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series o...Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series of paired-field experiments, we estimated the effects of revegetation types and environmental conditions on SOC stock and vertical distribution after replacement of cropland with poplar(Populus tomentosa) and korshinsk peashrub(Caragana korshinskii) in three climate regions(Chifeng City, Fengning City and Datong City of the ′Beijing-Tianjin Sandstorm Source Control′(BTSSC) program area. The results show that SOC sequestration rate ranges from 0.15 Mg/(ha·yr) to 3.76 Mg/(ha·yr) in the soil layer of 0–100 cm in early stage after cropland afforestation in the BTSSC program area. The SOC accumulation rates are the highest in Fengning for both the two vegetation types. Compared to C. korshinskii, P. tomentosa has greater effects on SOC accumulation in the three climate regions, but significantly greater effect only appears in Datong. The SOC density increases by 20%–111% and 15%–59% for P. tomentosa and 9%–63% and 0–73% for C. korshinskii in the 0–20 cm and 20–100 cm soil layers, respectively. Our results indicate that cropland afforestation not only affects SOC stock in the topsoil, but also has some effects on subsoil carbon. However, the effect of cropland afforestation on SOC accumulation varied with climate regions and revegetation types. Considering the large area of revegetation and relatively high SOC accumulation rate, SOC sequestration in the BTSSC program should contribute significantly to decrease the CO2 concentration in the atmosphere.展开更多
“Ejin Section” found in a typical vegetation-covered sand dune in Ejin Oasis was investigated. In this study, 263 samples were taken from the section for grain-size analysis, 25 for chemical analysis, 11 for 14C dat...“Ejin Section” found in a typical vegetation-covered sand dune in Ejin Oasis was investigated. In this study, 263 samples were taken from the section for grain-size analysis, 25 for chemical analysis, 11 for 14C dating and 6 for scanning electron microscope (SEM). The results of the study indicate that 3 types of the sediments in the section can be identified, YS, LS and ST. YS, homogeneous yellow-brown dune sands, is equal to those of inland deserts, LS, loess-like sandy soils, is the same as the sandy loess in the middle Yellow River and modern falling dusts, and ST, sandy sediments interbeded with the deadwood and defoliation of Tamarix spp, represents the depositional process of the section interrupted by abrupt changes in climate. The Ejin Section has recorded the repeated dust-storms or sandstorms since 2500 yr BP and the peak periods of the dust-storms or sandstorms revealed by the section are consistent with the records of “dust rains” in historical literatures, indicating that the change of climate is a key factor to increase sandstorms or dust-storms, whereas, “artificial” factor may only be an accelerating one for desertification.展开更多
ALASHAN AND ORDOS,Inner Mongolia-Dust,five centimeters thick, and rat holes cover the landscape of the Shilekai village,about 300 kilometers from the city of Ordos, Inner Mongolia.
During the course of a major sandstorm from April 17 to April 23,2008 in the Taklimakan Desert,data pertaining to the mass concentrations of different-sized atmospheric particulate matter were observed continuously wi...During the course of a major sandstorm from April 17 to April 23,2008 in the Taklimakan Desert,data pertaining to the mass concentrations of different-sized atmospheric particulate matter were observed continuously with Grimm 1.108,Thermo RP 1400a,TSP,and CAWS-600 instruments.The results showed that:(1) during the entire sandstorm process there were some differences between the daily mean particle concentration peaks and the hourly mean particle concentration peaks because the actual sandstorm lasted for only about 4 hr,whereas more particles were accumulated in the floating dust days before and after the actual sandstorm;(2) the intensity of the sandstorm was enhanced with the increase of wind speed,and this was related to the peak mass concentrations of atmospheric particulate matter;the wind speed directly affected the concentration of atmospheric particulate matter:the higher the wind speed,the higher the mass concentration(>0.23 μm was 39,496.5 μg/m 3,and >20.0 μm was 5,390.7 μg/m 3);(3) the concentration changes of PM 10 and TSP were also related to the course and intensity of the sandstorm;and(4) the mass concentration of atmospheric particulate matter had the following sequence during the dust weather:clear day < floating dust < floating and blowing dust < sandstorm.Temperature,relative humidity,and barometric pressure are important factors affecting the strength of storms,which could also indirectly affect the concentration change of atmospheric particulate matter.展开更多
The strong sandstorm weather process analysis has been done with the information digital diagrams method and times extended observation information on 23rd May,2004 in Gansu Province. The research results reveal the u...The strong sandstorm weather process analysis has been done with the information digital diagrams method and times extended observation information on 23rd May,2004 in Gansu Province. The research results reveal the unique mechanism structure of sandstorm disaster weather and the signification of irregular information,approve that the region digital diagrams has the capability to forecast the character and intension of transition disaster weather,and explain certainly that the meteorological problem is transformation problem of evolvement science.展开更多
Systematical analyses of spring sandstorms in 2000 affecting Beijing area are carried out. Results revealed the key dynamic mechanisms of dust storm during its mobilization, lifting, horizontal advection and depositio...Systematical analyses of spring sandstorms in 2000 affecting Beijing area are carried out. Results revealed the key dynamic mechanisms of dust storm during its mobilization, lifting, horizontal advection and deposition processes. It turns out that in the processes of sandstorms influencing Beijing area in March-April 2000, the dynamic conditions for dust mobilization are significantly correlated with phenomena, such as cold air-related climatic activities,clay soils area of North China and surface friction velocity anomaly. The characteristics of sandstorm can be described by composite mode of dust particles mobilization-lifting-long-range transport. This paper will provide scientific evidences for further studies,prediction and harness of sandstorms in China.展开更多
The favourable synoptic situation and climate background for a sandstorm process,which occurred in theperiod 9—16 April 1988,have been studied through analyzing weather maps,meteorological elements,satellitecloud pic...The favourable synoptic situation and climate background for a sandstorm process,which occurred in theperiod 9—16 April 1988,have been studied through analyzing weather maps,meteorological elements,satellitecloud pictures and sandstorm trajectories.The sand dust origin area,the directions and the paths of sanddust transport,and the extent the sand dust reached are also investigated.The results of measurments andanalysis indicate that the concentration of sand dust particles is 10 times greater than the normal.It is also shownthat the elements in the sand dust are lithophylic and come from natural source through the chemical composi-tion analysis of the sand dust,so that the sand dust has not been polluted by human activities.展开更多
文摘The severe sandstorm process in Ulanqab,Inner Mongolia on March 15,2021 was analyzed and discussed from the aspects of weather facts,weather causes and dynamic diagnosis.The results show that the strong cold air in West Siberia rapidly moved eastward,and the surface cold front moved eastward to Ulanqab with significant warming in the previous period,resulting in gale and sandstorm weather.This severe sandstorm process occurred in basically stable atmospheric stratification.During the strong sandstorm and extremely strong sandstorm process on March 15,the strong warming in the early period near the surface led to the surface thermal instability,and sand was generated by the upward movement of the Mongolian cyclone.Over the upper northwest air stream,barocline disturbance developed unsteadily,and the upper cold advection stimulated the secondary circulation of front perpendicular to the surface;the surface cyclone turned into strong cold front,and then strong sandstorm weather occurred in Ulanqab.
文摘Based on the data of sandstorm at 11 stations in Ulanqab City from 1990 to 2021,the spatial and temporal variation characteristics of sand-storm weather were analyzed firstly,and then the conceptual models of cold front and Mongolian cyclone sandstorm were obtained by analyzing sandstorm cases.Finally,the forecast points of the two types of sandstorm weather were given to provide some scientific basis and reference for the prediction of local sandstorm weather in the future.
基金Supported by the Scientific Research Project of Shaanxi Provincial Land Engineering Construction Group(DJNY2022-21)Shaanxi Province Youth Talent Promotion Program(YKJ202228).
文摘[Objectives]To explore the distribution characteristics of soil organic carbon in degraded forest land in the sandstorm area of Jingbian County,Shaanxi Province.[Methods]The distribution characteristics and abundance of 0-20 cm shallow soil organic carbon in 5 towns in the sandstorm area in the north of Jingbian County were studied by field sampling and indoor detection.[Results]The average soil organic carbon contents in Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town and Dongkeng Town were 2.93,3.21,2.53,2.54 and 4.08 g/kg,respectively,which were all lower than the national background value(31.00 g/kg).The coefficients of variation of soil organic carbon content in Hongdunjie Town,Huanghaojie Town and Dongkeng Town were 59.04%,35.97%and 47.55%,respectively,with higher coefficients of variation and larger differences in spatial distribution.The organic carbon content of Haizetan Town and Dongkeng Town was above the abundance,accounting for 70%and 50%,which were relatively rich,while the soil organic carbon content of Hongdunjie was relatively scarce.The average content of soil organic carbon in the sandstorm area was 3.03 g/kg,which was also lower than the national background value.The coefficient of variation was 46.53%,showing high coefficient of variation and large difference in spatial distribution.In addition,20.41%of the average content of soil organic carbon in the sandstorm area was in the deficient level,and 79.59%were in the medium or above level.[Conclusions]The study of distribution characteristics of soil organic carbon in degraded forest land in the sandstorm area of Jingbian County will better serve the precise management of soil resources.
基金supported by the National Natural Science Foundation of China(61771020,61471412,2019KD0AC02)。
文摘In this paper,we present a tensor least square based model for sand/sandstorm removal in images.The main contributions of this paper are as follows.First,an important intrinsic natural feature of outdoor scenes free of sand/sandstorm is found that the outlines in RGB channels are somewise similar,which discloses the physical validation using the tensor instead of the matrix.Second,a tensor least square optimization model is presented for the decomposition of edge-preserving base layers and details.This model not only decomposes the color image(taken as an inseparable indivisibility)in X,Y directions,but also in Z direction,which meets the statistical feature of natural scenes and can physically disclose the intrinsic color information.The model’s advantages are twofold:one is the decomposition of edgepreserving base layers and details that can be employed for contrast enhancement without artificial halos,and the other one is the color driving ability that makes the enhanced images as close to natural images as possible via the inherent color structure.Thirdly,the tensor least square optimization model based image enhancement scheme is discussed for the sandstorm weather images.Finally,the experiments and comparisons with the stateof-the-art methods on real degraded images under sandstorm weather are shown to verify our method’s efficiency.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (Grant No.2019QZKK0307)。
文摘Climate change influences both ecosystems and ecosystem services.The impacts of climate change on ecosystems and ecosystem services have been separately documented.However,it is less well known how ecosystem changes driven by climate change will influence ecosystem services,especially in climate-sensitive regions.Here,we analyzed future climate trends between 2040 and 2100 under four Shared Socioeconomic Pathway(SSP) scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5) from the Coupled Model Intercomparison Project 6(CMIP6).We quantified their impacts on ecosystems patterns and on the ecosystem service of sandstorm prevention on the Qinghai-Tibet Plateau(QTP),one of the most climate-sensitive regions in the world,using Random Forest model(RF) and Revised Wind Erosion Equation(RWEQ).Strong warming(0.04℃/yr) and wetting(0.65 mm/yr) trends were projected from 2015 to 2100.Under these trends,there will be increased interspersion in the pattern of grassland and sparse vegetation with meadow and swamp vegetation,although their overall area will remain similar,while the areas of shrub and needleleaved forest classes will increase and move toward higher altitudes.Driven by the changes in ecosystem patterns caused by climate change indirectly,grassland will play an irreplaceable role in providing sandstorm prevention services,and sandstorm prevention services will increase gradually from 2040 to 2100(1.059-1.070 billion tons) on the QTP.However,some areas show a risk of deterioration in the future and these should be the focus of ecological rehabilitation.Our research helps to understand the cascading relationship among climate change,ecosystem patterns and ecosystem services,which provides important spatio-temporal information for future ecosystem service management.
基金Under the auspices of National Natural Science Foundation of China (49894170)
文摘Sandstorm is a frequently occurred disastrous weather in northern China. The increasing occurrence frequency recently, especially the much more frequently occurred sandstorms with high intensity in the spring of 2000 have caused great loss to national economy. The combination of strong wind, exposed sandy soil on ground surface and unstable air current constitutes the necessary conditions for the sandstorms. However, the accelerated desertification process resulting from irrational human economic activities is responsible for the accelerated sandstorms. The effective measures to mitigate sandstorm lie in strengthening desertification control and eco-environmental protection.
基金Under the auspices of National Natural Science Foundation of China(No.41807177,41701017)the Pioneer‘Hundred Talents Program’of Chinese Academy of Sciences。
文摘Dominated by an arid and semiarid continental climate,the Beijing-Tianjin Sandstorm Source Region(BTSSR)is a typical ecologically fragile region with frequently occurring droughts.To provide information for regional vegetation protection and drought prevention,we assessed the relations between vegetation cover change(measured by the Normalized Difference Vegetation Index,NDVI)and the Standardized Precipitation Evapotranspiration Index(SPEI)at different time-scales,in different growth stages,in different subregions and for different vegetation types based on the Pearson's correlation coefficient in the BTSSR from 2000 to 2017.Results showed that 88.19%of the vegetated areas experienced increased NDVI in the growing season;48.3%of the vegetated areas experi-enced significantly increased NDVI(P<0.05)and were mainly in the south of the BTSSR.During the growing season,a wetter climate contributed to the increased vegetation cover from 2000 to 2017,and NDVI anomalies were closely related to SPEI.The maximum correlation coefficient in the growing season(Rmax)was significantly positive(P<0.05)in 97.84%of the total vegetated areas.In the vegetated areas with significantly positive Rmax,pixels with short time-scales(1-3 mon)accounted for the largest proportion(33.9%).The sensitivity of vegetation to the impact of drought rose first and then decreased in the growing season,with a peak in July.Compared with two subregions in the south,subregions in the north of the BTSSR were more sensitive to the impacts of drought variations,especially in the Xilingol Plateau and Wuzhumuqin Basin.All four major vegetation types were sensitive to the effects of drought variations,especially grasslands.The time-scales of the most impacting droughts varied with growth stages,regions,and vegetation types.These results can help us understand the relations between vegetation and droughts,which are important for ecological restoration and drought prevention.
基金Supported by the Project of Ulanqab Meteorological Bureau (20180709)。
文摘Based on the observational data, NCEP 1°×1° reanalysis data and potential vorticity theory, the occurrence mechanism of a strong sandstorm occurring in Inner Mongolia during March 14-15 was studied. The results show that the large potential vortex area in the upper troposphere moved eastward and downward, and a structure similar to a "funnel" appeared;the cyclone moved eastward and developed;the high potential vortex region always matched the region where the cyclone developed;the development of the cyclone was closely related to the cold air activity, and there was an obvious interaction between high-and low-altitude systems. The potential vorticity at 500 hPa had obvious significance for the influencing system of this sandstorm. The 0.5 PVU contour line can be used as the boundary of sandstorm weather area. On the potential temperature profile, the occurrence process of this sandstorm was the process of the expansion of cold air from high latitudes to low latitudes. When the high-value potential vorticity system slide along the isentropic surface, the lower vertical vorticity increased due to the increasing slope of the isentropic surface and the conservation of potential vorticity, leading to the development of the surface cyclone circulation and the enhancement of wind speed, and further causing the occurrence of this sandstorm.
文摘The aim of the study is to classify the Sandstorms according to year seasons as well as their spatial variation in Saudi Arabia. Factor analysis has been used for data collection. Three factors have been presented: the first factor related to Spring as a prime Season for Dust Sandstorms. Factor two shows that Samar months concern as ascend season for Sandstorms, while the Autumn Season comes as a third period for Dust Sandstorms. With regard to spatial variation, Al-Ahsa station came as the most closely related station in the spring season, followed by Hafr Elbatten, Jazan and Al-Jouf stations, while Jazan and Yenbo stations were the most connected stations in the summer season, Turaif is more closely related, to Fall season. By the end of the study several results and recommendations have been addressed.
文摘The main causes of the heavysandstorms ravaging north Chinathis spring are abnormal climateand the encroachment ofdesertification, says a CAS reportreleased in Beijing on May 15.
基金The Knowledge Innovation Programof the Chinese Academy of Sciences(No. KZCX3-SW-341) and the Cold and Arid Environmental and EngineeringResearchInstitute(No.2004105)
文摘The purpose of this present study is to investigate the frequency and variation of sandstorm in Minqin Oasis. Using daily observational data of sandstorm and other meteorologic data from 1954 to 2000, we have illuminated the relationship between sandstorm, meteorological parameters and human activities. The results of the analysis show that the highest frequency of sandstorms occurrence and their duration mainly focus on March, April and May, especially in April. Most of sandstorms occur from midday to nightfall, but relative few appear from midnight to forenoon, which apparently correlates to the daily variations of atmospheric thermal stability within atmospheric boundary layer. Monthly mean and annual mean duration of sandstorms coincide well with the frequencies of sandstorm occurrence.
基金Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05060600)Knowledge Innovation Programs of Chinese Academy of Sciences(No.KSCX2-EW-J-5)National Key Technology Research and Development Program of China(No.2011BAD31B02)
文摘Land use change is one of the major factors that affect soil organic carbon(SOC) variation and global carbon balance. However, the effects of land use change on SOC are always variable. In this study, using a series of paired-field experiments, we estimated the effects of revegetation types and environmental conditions on SOC stock and vertical distribution after replacement of cropland with poplar(Populus tomentosa) and korshinsk peashrub(Caragana korshinskii) in three climate regions(Chifeng City, Fengning City and Datong City of the ′Beijing-Tianjin Sandstorm Source Control′(BTSSC) program area. The results show that SOC sequestration rate ranges from 0.15 Mg/(ha·yr) to 3.76 Mg/(ha·yr) in the soil layer of 0–100 cm in early stage after cropland afforestation in the BTSSC program area. The SOC accumulation rates are the highest in Fengning for both the two vegetation types. Compared to C. korshinskii, P. tomentosa has greater effects on SOC accumulation in the three climate regions, but significantly greater effect only appears in Datong. The SOC density increases by 20%–111% and 15%–59% for P. tomentosa and 9%–63% and 0–73% for C. korshinskii in the 0–20 cm and 20–100 cm soil layers, respectively. Our results indicate that cropland afforestation not only affects SOC stock in the topsoil, but also has some effects on subsoil carbon. However, the effect of cropland afforestation on SOC accumulation varied with climate regions and revegetation types. Considering the large area of revegetation and relatively high SOC accumulation rate, SOC sequestration in the BTSSC program should contribute significantly to decrease the CO2 concentration in the atmosphere.
基金National Basic Research Program of China, No.2004CB720206 Knowledge Innovation Project of CAS, No.KZCX2-SW-118
文摘“Ejin Section” found in a typical vegetation-covered sand dune in Ejin Oasis was investigated. In this study, 263 samples were taken from the section for grain-size analysis, 25 for chemical analysis, 11 for 14C dating and 6 for scanning electron microscope (SEM). The results of the study indicate that 3 types of the sediments in the section can be identified, YS, LS and ST. YS, homogeneous yellow-brown dune sands, is equal to those of inland deserts, LS, loess-like sandy soils, is the same as the sandy loess in the middle Yellow River and modern falling dusts, and ST, sandy sediments interbeded with the deadwood and defoliation of Tamarix spp, represents the depositional process of the section interrupted by abrupt changes in climate. The Ejin Section has recorded the repeated dust-storms or sandstorms since 2500 yr BP and the peak periods of the dust-storms or sandstorms revealed by the section are consistent with the records of “dust rains” in historical literatures, indicating that the change of climate is a key factor to increase sandstorms or dust-storms, whereas, “artificial” factor may only be an accelerating one for desertification.
文摘ALASHAN AND ORDOS,Inner Mongolia-Dust,five centimeters thick, and rat holes cover the landscape of the Shilekai village,about 300 kilometers from the city of Ordos, Inner Mongolia.
基金supported by Natural Science Foundation of China (Nos. 41175017,41175140)Public Service sectors (meteorology) research and special funds by the Ministry of Science and Technology (Nos.GYHY201006012,GYHY201106025)
文摘During the course of a major sandstorm from April 17 to April 23,2008 in the Taklimakan Desert,data pertaining to the mass concentrations of different-sized atmospheric particulate matter were observed continuously with Grimm 1.108,Thermo RP 1400a,TSP,and CAWS-600 instruments.The results showed that:(1) during the entire sandstorm process there were some differences between the daily mean particle concentration peaks and the hourly mean particle concentration peaks because the actual sandstorm lasted for only about 4 hr,whereas more particles were accumulated in the floating dust days before and after the actual sandstorm;(2) the intensity of the sandstorm was enhanced with the increase of wind speed,and this was related to the peak mass concentrations of atmospheric particulate matter;the wind speed directly affected the concentration of atmospheric particulate matter:the higher the wind speed,the higher the mass concentration(>0.23 μm was 39,496.5 μg/m 3,and >20.0 μm was 5,390.7 μg/m 3);(3) the concentration changes of PM 10 and TSP were also related to the course and intensity of the sandstorm;and(4) the mass concentration of atmospheric particulate matter had the following sequence during the dust weather:clear day < floating dust < floating and blowing dust < sandstorm.Temperature,relative humidity,and barometric pressure are important factors affecting the strength of storms,which could also indirectly affect the concentration change of atmospheric particulate matter.
文摘The strong sandstorm weather process analysis has been done with the information digital diagrams method and times extended observation information on 23rd May,2004 in Gansu Province. The research results reveal the unique mechanism structure of sandstorm disaster weather and the signification of irregular information,approve that the region digital diagrams has the capability to forecast the character and intension of transition disaster weather,and explain certainly that the meteorological problem is transformation problem of evolvement science.
基金This work was supported by Key Projects of National Fundamental Research Planning (Grant No. G1999045700).
文摘Systematical analyses of spring sandstorms in 2000 affecting Beijing area are carried out. Results revealed the key dynamic mechanisms of dust storm during its mobilization, lifting, horizontal advection and deposition processes. It turns out that in the processes of sandstorms influencing Beijing area in March-April 2000, the dynamic conditions for dust mobilization are significantly correlated with phenomena, such as cold air-related climatic activities,clay soils area of North China and surface friction velocity anomaly. The characteristics of sandstorm can be described by composite mode of dust particles mobilization-lifting-long-range transport. This paper will provide scientific evidences for further studies,prediction and harness of sandstorms in China.
文摘The favourable synoptic situation and climate background for a sandstorm process,which occurred in theperiod 9—16 April 1988,have been studied through analyzing weather maps,meteorological elements,satellitecloud pictures and sandstorm trajectories.The sand dust origin area,the directions and the paths of sanddust transport,and the extent the sand dust reached are also investigated.The results of measurments andanalysis indicate that the concentration of sand dust particles is 10 times greater than the normal.It is also shownthat the elements in the sand dust are lithophylic and come from natural source through the chemical composi-tion analysis of the sand dust,so that the sand dust has not been polluted by human activities.
