Analysis on temporal and spatial variations of groundwater hydrochemical characteristics in the past decade in southern plain of Beijing, China

Groundwater utilization and protection are crucial for sustainable urban development. This is especially true for Beijing, where groundwater is an important source for urban water supply. In this study, statistical methods, including descriptive statistics, correlation analysis, principal component analysis, and Piper-Tri-linear diagram, were used in analyzing the temporal and spatial variations of the hydrochemical characteristics of groundwater based on monitored data from the southern plain of Beijing, China. Results indicated consistent changes of groundwater's hydrochemical characteristics in different aquifers in the study area. The percentage of HCO_3^-in total anion increased significantly in the groundwater, and hydrochemical water type evolved gradually from Ca-Mg-Cl-SO_4 based to Ca-Mg-HCO_3 based from period 2005-2007 to period 2013-2015. In shallow groundwater, the concentration of Na^+, Ca^(2+), SO_4^(2-), HCO_3^-, and total dissolved solids(TDS) increased from period 2005-2007 to period 2013-2015, and the greatest change came from HCO_3^-, rising from 428.93 to 528.96 mgL^(-1). The changes of main ionic concentrations in the deep groundwater were consistent with those in the shallow groundwater for both periods. However, the variations in deep groundwater were less than those in shallow groundwater. The temporal and spatial variations of hydrochemical characteristics reflect the groundwater quality in the study area. This study could facilitate decision-making process on the protection of groundwater resources to ensure its sustainable utilization.

Spatial and Temporal Variation Characteristics of Gale Days in China from 1961 to 2016

Based on data of hail days at 2 481 stations during 1961-2016,the temporal and spatial distribution characteristics and periodic variation of gale days in China and seven geographical regions were analyzed by using a variety of statistical methods. The results showed that: in time,the gale days in China and the seven geographical areas all showed a decreasing trend from 1961 to 2016. In the Tibet( Southeast China and Southwest China) region,the annual number of single-station gale days was the most( least),but the decrease ratio was the least( most). In the significance oscillation period,it was 14 years in the whole country,60 years in Northeastern China,Northern China and east part of Northwestern China,7,14 and 60 years in the west of Northwestern China,Southwestern China and Southeastern China,7 and 60 years in the Tibet region. The mutation of gale days generally occurred in 1991,1993,1989,1997,1986,1997,1992 and 1984 in the whole country,Northeastern China,Northern China,east part of Northwestern China,west part of Northwestern China,Tibet,Southwestern China and Southeastern China,but only the east of Northwestern China and Tibet region passed 0. 05 of significance test. In space,the annual average gale days showed the pattern of southeast low and northwest high in China from 1961 to 2016. The annual average gale days were more abundant in the central and western Tibet,the southern Qinghai,eastern Xinjiang,western Sichuan,northern Inner Mongolia and northern Gansu. These regions were dominated by positive anomaly in the 1970 s and the 1980 s,but negative in other decades. Annual gale days in most regions of China showed a decreasing trend during 1961-2016,and fluctuation presented high in east region and low in west region beside " Hu Huanyong line".

Study on Temporal and Spatial Characteristics of Climate Variation in Hebei Area during 1956-2007

[Objective] The research aimed to study temporal and spatial characteristics of climate variation in Hebei area during 1956-2007. [Method] Based on the data from 23 weather stations evenly distributed over Hebei area (included Beijing and Tianjin) during 1956-2007, by using statistical analytic method, the temporal and spatial variation characteristics of main meteorological factors (temperature and precipitation, etc.) in the area were analyzed. The variation fact and evolution rule of climate in the area in 52 years were discussed. [Result] In Hebei area during 1956-2007, the annual and four-season temperatures both presented wavy rise trends. The temperature increment in winter was the maximum, contributing the most to the annual temperature elevation in this area. The temperatures in the whole district all presented rise trends, and the variation difference had regularity. The annual and four-season rainfalls both had large fluctuation amplitudes, following different linear variation trends. The annual rainfall overall presented wavy decrease trends. The spatial difference of rainfall variation was significant. The rainfalls in the whole district all presented decrease trends. The decrease amplitude presented low-high-low pattern from the northeast to the southwest. The potential evaporation capacity over the whole district was the highest in the 1960s, and decreased ever since instead of increasing with the temperature. The potential evaporation capacities of each season also presented decline trends. Except in Fengning and Yuxian, the evaporation capacities of other stations in the whole district all presented decline trends. The relative humidity slightly decreased as time, with the exception of Chengde, Qinhuangdao and Nangong. The sunshine hours had a clear decrease trends. [Conclusion] The research provided scientific basis for realizing regional sustainable development, improving ecological environment and people’s life quality.

Temporal-spatial Variation Characteristics of the Extreme Precipitation Days over South China from 1961 to 2010

[ Objective] The research aimed to analyze temporal-spatial variation characteristics of the extreme precipitation days over South China from 1961 to 2010. [ Method] Based on the daily precipitation data in meteorological stations over South China, extreme precipitation thresholds were determined according to the percentiles distribution for different stations. Temporal-spatial variation characteristics of the extreme precipitation days over South China were studied by the methods of fuzzy clustering, trend coefficient, wavelet analysis and cross spectrum analysis, etc. [ Re- suit] Four sub-regions were identified over South China. They were respectively Nanling area, west Guangxi area, Coast area and Hainan area. Occurrence seasons of the extreme precipitations in each sub-region were significantly different. Extreme precipitation clays in four sub-regions all had increase trends, and those of Nanling area and Coast area were significant. From wavelet analysis and cress spectrum analysis, there were significant periodic variation characteristics. Extreme precipitation days in each sub-region all had significant same-phase evolution trends at the peri- od of 2 -5 years, but backward time length was different. [ Conclusion] The research provided background materials for forecast and influence as- sessment of the extremely heavy precipitation over South China.

Spatial and temporal variation of water mass mixing characteristic in the East China Sea

On the basis of the observation data of Kuroshio since 1984 and relative historical data in the East China Sea, spatial and temporal variation of water mass mixing characteristic in the observation area is analysed. The main results are as follows.

Effects of Normalized Difference Vegetation Index and Related Wavebands′ Characteristics on Detecting Spatial Heterogeneity Using Variogram-based Analysis

Spatial heterogeneity is widely used in diverse applications, such as recognizing ecological process, guiding ecological restoration, managing land use, etc. Many researches have focused on the inherent scale multiplicity of spatial heterogeneity by using various environmental variables. How these variables affect their corresponding spatial heterogeneities, however, have received little attention. In this paper, we examined the effects of characteristics of normalized difference vegetation index （NDVI） and its related bands variable images, namely red and near infrared （NIR）, on their corresponding spatial heterogeneity detection based on variogram models. In a coastal wetland region, two groups of study sites with distinct fractal vegetation cover were tested and analyzed. The results show that： l） in high fractal vegetation cover （H-FVC） area, NDV! and NIR variables display a similar ability in detecting the spatial he- terogeneity caused by vegetation growing status structure; 2） in low fractal vegetation cover （L-FVC） area, the NIR and red variables outperform NDVI in the survey of soil spatial heterogeneity; and 3） generally, NIR variable is ubiquitously applicable for vegetation spatial heterogeneity investigation in different fractal vegetation covers. Moreover, as variable selection for remote sensing applications should fully take the characteristics of variables and the study object into account, the proposed variogram analysis method can make the variable selection objectively and scientifically, especially in studies related to spatial heterogeneity using remotely sensed data.

Intermonthly Difference of Multi-attribute Characteristics of Rainstorm in China Based on Spatial-temporal Differentiation

Based on the daily precipitation data of 545 meteorological stations in China from 1961 to 2016, the spatial-temporal variation characteristics of rainstorm rainfall and rainy days in different months of China were diagnosed from three aspects: climatic characteristics, variation trend and interannual variation. The results showed that:(1) Rainstorm rainfall and rainy days in different months of China from 1961 to 2016 had similar spatial characteristics in corresponding months. From January to July, the high-value areas of rainstorm rainfall and rainy days gradually expanded from southeast coast to northwest inland, but mainly distributed in the east area of Hu Huanyong Line. From August to December, it shrank from northwest to southeast coastal areas. Rainstorm rainfall and rainy days were less distributed in different months in the west area of Hu Huanyong Line;(2) From 1961 to 2016, the spatial-temporal variation characteristics of rainstorm rainfall in different months in China were basically consistent with that of rainy days. May to August was the most significant month for the variation trend of rainstorm rainfall and rainy days in China. It mainly distributed in the southeast monsoon area, and was mainly increasing trend. The trend of rainstorm rainfall and rainy days in northwest China changed slightly in different months;(3) The interannual variability of rainstorm rainfall in different months in China from 1961 to 2016 was similar to that of rainy days. The fluctuation characteristics from April to October were larger in the northern region. The southern region fluctuated greatly from November to December in January to March. With the development of the month, the high-value areas with large daily fluctuations of rainstorm rainfall and rainy days gradually expanded from southeast to northwest, northeast and southwest, and the fluctuations in southeast tended to decrease, then shrank from northwest, northeast and southwest to southeast, with the increasing fluctuations in southeast. The study has certain reference significance for flood control and disaster reduction and water resources planning and utilization.

Spatial-temporal Variation of Extreme Precipitation Events in Northwest China During 1961-2010

Using the daily precipitation data of 118 meteorological stations in Northwest China from January 1, 1961 to December 31,2010, we analyzed extreme precipitation events from prime precipitation data by applying R-language Climate Index （RClimDex）. The spatial-temporal change characteristics in the past 50 years have been examined using the method of trend analysis, Mann-Kendall and the spatial analysis module of Arcgis9.2. The results show that the spatial distribution of the indices for extreme precipitation in Northwest China is greatly influenced by geographic location, atmospheric circulation and topography, and the spatial difference of extreme precipitation events is very evident, while the indices reduce from the southeast to the northwest except Consecutive Dry Days （CDD）. In Xinjiang region, high values appear in Tianshan Mountains and decrease towards the south and north respectively. In the past 50 years, the temporal variation tendency of the indices for extreme precipitation in Northwest China has a great spatial distinction. It shows that the variation tendency is opposite between the east （decrease） and the west （increase）, and CDD has a decreasing tendency while other indices increase. For each region, it is found that the indices for extreme precipitation in Xinjiang and Qinghai Province shows an increasing trend, and it is remarkable in Tianshan Mountains, the north of Xinjiang and the northeast of Qinghai Province. The temporal variation tendency of the indices for extreme precipitation in Ningxia, Shaanxi and Gansu has a large spatial distinction. The stations which have an increasing tend are mainly found in the north of Ningxia, south of Shaanxi and Hexi Corridor of Gansu. However, the south of Ningxia, north of Shaanxi and Longnan of Gansu Province mainly present a decreasing trend. The temporal variation tendency of the indices for extreme precipitation in Inner Mongolia is not obvious. Overall, the east part of Northwest China has a dry tendency, while the west part has an opposite trend.

Comparison of temporal and Spatial Characteristics of Ozone Pollution at Ground Level in the Eastern China

Monitoring data from ozone（O3） automatic stations in three typical cities with different climatic areas in the southern and northern parts of eastern China are used to analyze temporal and spatial characteristics of ozone pollution at ground level. The results show that ozone pollution level has distinct regional differences and the concentration in the suburbs is higher than that in the urban areas. The seasonal variation of ozone concentration in different climatic areas is greatly affected by the variation of precipitation. Ozone concentration in Shenyang and Beijing , in the temperate zone, has one perennial peak concentration, occurring in early summer, May or June. Ozone concentration in Guangzhou, in sub-tropical zone, has two peak values year round. The highest values occur in October and the secondary high value in June. The ozone season in the south is longer than that in the north. The annual average daily peak value of ozone concentrations in different climates usually occur around 3 pm. The diurnal variation range of ozone concentration declines with the increase of latitude. Ozone concentration does not elevate with the increase of traffic flow. Ozone concentration in Guangzhou has a distinct reverse relation to CO and NOx. This complicated non-linearity indicates that the equilibrium of ozone photochemical reaction has regional differences. Exceeding the rate of Beijing＇s lh ozone concentration is higher than that of Guangzhou, whereas the average 8h ozone level is lower than that of Guangzhou, indicating that areas in low latitude are more easily affected by moderate ozone concentrations and longer exposure. Thus, China should work out standards for 8h ozone concentration.

County scale spatial differential characteristics of cultivated land use grade: A case of Binchuan County

Land resource is the material foundation of human survival and economic development, and the cultivated land is the essence of land resources. This paper takes the county scale, by using the method of GIS spatial analysis and statistical analysis unifies, to explore the quality of cultivated land in Binchuan County using level, and explain the utilization level of county cultivated land quality spatial differentiation characteristics. The results showed that:(1) in the quantity of cultivated land quality and utilization level, the average utilization of paddy land was greater than that of dry land, and the comprehensive utilization of cultivated land and so on. Among them, the paddy land ranged from grade 6 to 15, the average utilization was grade 11.6; dry land ranged from grade 2 to 11, the average utilization was grade 5.9; comprehensive range of cultivated land is grade 2 to 15, the average utilization was grade 8.1;(2) the quality of cultivated land utilization spatial differentiation. Paddy field, dry land and cultivated land and large value distribution in the central and southern, inverted V shape distribution; the smaller the value distribution in the East and West, a dumbbell shaped distribution. Among them, they don't use a larger value of paddy land distributed in the central, South and southwest, the maximum value is 14.3, the smaller the value distribution in the West and East, the minimum value is grade 7; the larger the value distribution by the dry land in the South and West, the maximum value is grade 10.2, the smaller the value distribution in the West and East. The minimum value is grade 2.3; the comprehensive utilization of cultivated land don't distributed larger value in the central, South and south-west, the maximum value is grade 12.7, the smaller the value distribution in the West and East, the minimum value is grade 3.5. This paper can provide scientific basis for the dynamic monitoring of cultivated land quality, the transformation of low yield farmland and the early warning of cultivated land pressure.

Relationship between catchment characteristics and nitrogen forms in Cao-E River Basin, Eastern China

The distribution of different nitrogen forms and their spatial and temporal variations in different pollution types of tributaries or reaches were investigated. Based on the catchments characteristics the tributaries or reaches can be classified into 4 types, including headwater in mountainous areas （type Ⅰ）, agricultural non-point source （NPS） pollution in rural areas （type Ⅱ）, municipal and industrial pollution in urban areas （type Ⅲ）, and combined pollution in main stream （type IV）. Water samples were collected monthly from July 2003 to June 2006 in the Cao-E River Basin in Zhejiang, eastern China. The concentrations of NO3^--N, NH4^＋ -N, and total nitrogen （TN） were measured. The mean concentrations of NO3^- -N were decreased in the sequence type IV 〉 type Ⅱ〉 type Ⅲ 〉 type Ⅰ, whereas, NH4^＋-N, total organic nitrogen （TON）, and TN were in the sequence： type Ⅲ〉 type Ⅳ 〉 type Ⅱ〉 type Ⅰ. In headwater and rural reaches, CNO^-2-N was much higher than Crea^＋ 4-N. In urban reaches, TON and NH4^＋ -N were the main forms, accounting for 54.7% and 32.1% of TN, respectively. In the whole river system, Crea^＋ 4--N decreased with increasing distance from cities, and CNo^-3 -N increased with the increasing area of farmland in the catchments. With increased river flow, CNO^-3 N increased and Crea4^＋-N decreased in all types of reaches, while the variations of CTON and CTN were different. For TN, the concentration may be decreased with the increase of river flow, but the export load always increased.

Analysis on the Gale Climate Characteristics and Circulation Situation in Jinzhou Area

Based on the gale observation data in 5 observation stations in Jinzhou area from 1973 to 2007,the gale trend and the periodic change in Jinzhou area were analyzed by using the linear trend estimation method and the spectral analysis method. Meanwhile,the circulation situation characteristics and the spatial-temporal distribution characteristics of gale in four seasons were discussed by surveying generally the weather charts. The results showed that the gale in Jinzhou area presented the fluctuation decline trend and had 3.5,7.0 years periodic changes. The gale in spring is the most and in summer was the least. It was less in winter and autumn. Seen from the analysis on the circulation situation,the gale circulation situation in Jinzhou area was similar to in Liaoning. The circulation situation in spring was basically consistent with in autumn,winter. The main situations had 3 kinds:north high south low(west high east low) ,two high clipping low,south high north low(east high west low) . In summer,the regional gale weather was mainly caused by the meso-micro scale system.

Fine Particulate Pollution Characteristics in Jinan City

The characteristics of fine particulate pollution(PM10 and PM2.5) were measured at urban and suburban sites in Jinan during the 2008-2009 heating and non-heating seasons.The results showed that PM10 and PM2.5 pollution was quite serious,and PM mass concentration was higher during the heating season than the non-heating season.PM was the highest in the chemical factory and lowest in the development zone.The mass concentrations of PM10 and PM2.5 were linearly related,and the mass concentration ratio of PM2.5/PM10 was up to 0.59 in urban areas.PM pollution in Jinan was related to local meteorological factors:PM2.5 mass concentration and humidity were positively correlated,and PM2.5 mass concentration was negatively correlated with both click on the temperature and wind speed,although wind speed varied more.

Asymmetrical Change Characteristics of Maximum and Minimum Temperatures in Shangqiu in Recent 50 Years

[Objective] The research aimed to analyze temporal and spatial variation characteristics of temperature in Shangqiu City during 1961-2010.[Method] Based on temperature data in eight meteorological stations of Shangqiu during 1961-2010,by using trend analysis method,the temporal and spatial evolution characteristics of annual average temperature,annual average maximum and minimum temperatures,annual extreme maximum and minimum temperatures,daily range of annual average temperature in Shangqiu City were analyzed.M-K method was used to determine mutation year of temperature.[Result] The annual average temperature,annual average minimum temperature and annual extreme minimum temperature respectively rose at 0.122,0.255 and 0.488 ℃/10 a.The variation trend of annual average maximum temperature wasn’t obvious.The daily range of annual average temperature and annual extreme maximum temperature respectively declined at-0.217 and-0.292 ℃/10 a.Seen from spatial distribution,the increase amplitudes of annual average temperature,annual average minimum temperature and annual extreme minimum temperature were all large in the east and small in the west.The decrease amplitude of daily range of annual average temperature was large in the east and small in the west.The decrease amplitude of annual extreme maximum temperature was large in the west and small in the east.The annual average maximum temperature had trends of increase and decrease.The annual average temperature,annual average minimum temperature and daily range of annual average temperature all mutated in 1997.The annual average maximum temperature didn’t have obvious mutation point.The annual extreme maximum temperature mutated in 1973.The annual extreme minimum temperature respectively mutated in 1989 and 1999.[Conclusion] The research played important guidance significances in adjustment of agricultural production structure,regional climate planning,reasonably using climate resource and replying climate change in Shangqiu City.

Spatial-temporal characteristics of lake area variations in Hoh Xil region from 1970 to 2011

As one of the areas with numerous lakes on the Tibetan Plateau, the Hoh Xil region plays an extremely important role in the fragile plateau eco-environment. Based on topographic maps in the 1970s and Landsat TM/ETM＋ remote sensing images iin the 1990s and the period from 2000 to 2011, the data of 83 lakes with an area above 10 km2 each were obtained by digitization method and artificial visual interpretation technology, and the causes for lake variations were also analyzed. Some conclusions can be drawn as follows. （1） From the 1970s to 2011, the lakes in the Hoh Xil region firstly shrank and then expanded, in particular, the area of lakes generally decreased during the 1970s-1990s. Then the lakes expanded from the 1990s to 2000 and the area was slightly higher than that in the 1970s. The area of lakes dramatically increased after 2000. （2） From 2000 to 2011, the lakes with different area ranks in the Hoh Xil region showed an overall expansion trend. Meanwhile, some regional differences were also discovered. Most of the lakes expanded and were widely distributed in the northern, central and western parts of the region. Some lakes were merged together or overflowed due to their rapid expansion. A small number of lakes with the trend of area decrease or strong fluctuation were scattered in the central and southern parts of the study area. And their variations were related to their own supply conditions or hydraulic connection with the downstream lakes or rivers. （3） The increase in precipitation was the dominant factor resulting in the expansion of lakes in the Hoh Xil region. The secondary factor was the increase in meltwater from glaciers and frozen soil due to climate warming.

成都平原经济区城市空气质量时空变化特征

基于2016—2020年成都平原经济区城市空气质量监测数据,应用空气质量综合指数评价法、Pearson相关分析法,对成都平原经济区空气质量时空变化特征、成都市主要污染物变化特征进行了研究.结果表明:1)2016—2020年,成都平原经济区城市群中空气质量指数出现了2个高值和2个低值中心,高值中心分别位于成都市、德阳市,2个低值中心分别位于雅安市、遂宁市,即成都市和德阳市空气质量最差,雅安市和遂宁市的空气质量最优;对于不同季节,1—12月,成都平原经济区的空气质量综合指数呈U字型变化,即空气质量6—10月较好,11月—次年2月较差.2)2016—2020年,成都市PM_(2.5)质量浓度值皆超过了国家二级标准限值,并且以PM_(2.5)为首要污染物出现频率最高,而O_(3)、CO、SO_(2)年均质量浓度在研究时段内均低于国家二级标准质量浓度限值.3)2016—2020年,成都市PM_(2.5)质量浓度与能见度呈显著负相关;年尺度上,成都市PM_(2.5)质量浓度与平均气温呈低度负相关,与风速、降水量呈弱负相关;季尺度上,除气温在春、夏、冬季节与PM_(2.5)质量浓度呈弱正相关外,4个季节中PM_(2.5)质量浓度与风速、降水量皆呈弱负相关.4)影响成都市PM_(2.5)质量浓度的社会经济因子主要是汽车尾气、工业烟(粉)尘排放.PM_(2.5)与地区生产总值、工业增加值、机动车保有量呈高度负相关,与工业烟(粉)尘排放量呈高度正相关.

SPATIAL AND TEMPORAL VARIATIONS OF THE KINEMATIC CHARACTERISTICS IN THE PROPAGATION OF ATMOSPHERIC STATIONARY WAVES

Time-mean global general circulation data are employed to analyze the temporal and spatial variations of the meridional gradient of zonal mean potential vorticity,the critical wavenumber n_s for horizontal wave- propagation,and the critical wavenumber K_c for vertical wave-propagation.Thereby the kinematic charac- teristics in the propagation of atmospheric stationary waves and their annual variations are studied.Results show that in the troposphere n_s and K_c usually decrease with the increase of either latitude or altitude. Synoptic and near-resonant Rossby waves could be trapped during their upward and meridional propagations. These characteristics possess prominent annual variations,especially in the Northern Hemisphere.It is found that the spatial and temporal variations of these kinematic characteristics are in good agreement with those of the atmospheric wave patterns.

山西省秋季降水的时空变化特征及成因分析

利用山西省1961-2021年秋季降水资料、NCEP/NCAR再分析资料和海温资料,分析山西省秋季降水的时空变化特征。结果表明:山西省秋季降水在20世纪70年代中期前偏多,之后减少,21世纪00年代中期又开始增多。进一步从大气环流角度探讨这种年代际变化的成因可知,在降水偏多时期,200 hPa纬向风场东亚西风急流位置偏北,有利于山西地区上升运动增强;500 hPa位势高度场上欧亚大陆上空呈现出显著的正-负-正异常分布,有利于高纬冷空气向南爆发;850 hPa风场有利于低纬水汽向山西输送,在这样的高低空环流配置下,有利于山西省降水增加。同时山西省秋季降水量与海温异常存在密切关系,当前期3-5月北太平洋中部海温偏高,热带中东太平洋海温偏低时,山西省南部秋季降水易偏多。

南平烤烟大田生长期气候要素时空变化特征

气候对于烤烟生长发育和烟叶品质有重要影响,为明确南平烟区烤烟大田期气候要素的变化特征,利用南平气象局提供的1971—2019年烟草大田生长期(1月中旬—7月中旬)旬气候资料,采用Mann-Kendall方法进行突变检测,分析了气温、降水量及日照时数等典型气候要素的时间及空间变化特征。结果表明,烤烟大田生长期逐年日照时数趋于减少,气温和降水量趋于增加,时间拐点在1995年。气候突变主要发生在春烟的气温和日照时数要素上,分别发生在1970s中期和2000s前期,降水量要素未发生突变。早春烟和春烟大田生长期气温在北部较低,南部及中部气温较高;降水量北部较高,南部及中部较低;日照时数整体表现为自西向东或东南逐渐增加。随着烤烟生育期进行,大田生长期气温逐渐升高,日照时数自6月下旬快速增加,强降水主要集中在6月,早春烟和春烟各生育期日照时数差异主要在伸根期和成熟期。研究结果对合理利用气候资源、趋利避害、提高烟叶产质量有重要的宏观指导意义。

1998—2020年若尔盖地区植被NDVI变化特征及驱动因子分析

【目的】植被是陆地碳汇的主体,利用归一化植被指数(Normalized difference vegetation index,NDVI)分析时空变化特征与驱动因子的关系在区域生态稳定研究中具有重要意义。【方法】基于若尔盖地区植被NDVI、气候、土壤、植被类型和地形数据,运用一元线性回归分析、变异系数和地理探测器方法,分析了1998—2020年若尔盖地区植被NDVI时空变化特征及其驱动因子。【结果】结果表明:(1)1998—2020年若尔盖地区植被总体呈波动上升趋势,多年平均植被NDVI为0.79,年均增速为0.004 3,植被改善趋势明显;空间分布整体呈东南高西北低的格局,多年平均植被NDVI在0.7以上的区域面积比例为96%。(2)1998—2020年若尔盖地区植被NDVI年际变化率较低,平均值为0.001 0,表现为稳定区域的面积比例为99.5%;23年平均变异系数为16.50%,植被状态总体较平稳,变异系数低于20%的面积比例为85%。(3)海拔和气温是若尔盖地区植被NDVI变化的主导自然地理因子,坡度和坡向对植被NDVI影响较小;各自然地理因子之间对植被NDVI的相互作用主要为双因子增强(11.11%)和非线性增强(88.89%)。【结论】若尔盖地区植被在近23年来整体得到了改善,其植被保护和恢复的措施及模式选择应充分考虑海拔、气温等自然地理因子的影响。