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基于青海高原1961 - 2018年47个气象站昼夜雨量数据， 分析了青海高原及各生态功能区的昼夜雨量及雨日的时空变化特征。结果表明： 近58年来， 青海高原昼夜雨量空间分布基本一致， 总体表现为东南向西北减少， 夜雨日多于昼雨日分布。青海高原昼夜雨量总体均呈增多趋势， 昼雨量的增加速率大于夜雨量； 从空间分布来看， 柴达木盆地西部、 东部农业区大部及青南牧区南部少数地区昼夜雨量呈减少趋势， 而柴达木盆地东部、 环青海湖地区、 青南牧区大部昼夜雨量均呈增多趋势。青海高原昼雨日略有增加， 夜雨日有减少趋势； 在地域上， 柴达木盆地昼夜雨日增多趋势明显， 而东部农业区昼夜雨日减少趋势明显。青海高原昼夜雨量分别呈2 a、 3 a的周期。近58年来， 青海高原、 东部农业区、 环青海湖地区、 柴达木地区昼雨量均无明显的突变现象， 仅青南牧区昼雨量在2003年前后存在明显突变现象； 青海高原、 东部农业区、 青南牧区夜雨量无明显突变现象， 环青海湖地区、 柴达木盆地夜雨量分别在1979年、 2003年出现了突变现象。 相似文献
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利用SPOT VGT NDVI数据对石羊河流域1999—2010年期间植被覆盖的时空变化进行了研究,并基于像元二分模型求算植被覆盖度,以植被覆盖度为指标对研究区荒漠化程度进行定量监测与评价。结果表明:12年来石羊河流域植被覆盖度整体呈增加的趋势,增加速率为0.003 2 a-1。植被改善的面积远大于植被退化的面积,植被改善区域的面积为11 130 km2,占研究区总面积的26.45%,主要分布在金昌、永昌、民勤、武威东部以及古浪的西北部地区;植被退化区域的面积为3 546 km2,占研究区总面积的8.43%,主要分布在天祝藏族自治县的东部和古浪南部的乌鞘岭地区。荒漠化土地面积整体呈下降的趋势,极重度荒漠化土地明显减少,转化为重度荒漠化;非荒漠化土地的增加主要以绿洲的扩张为主。 相似文献
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西北地区空中水汽时空分布及变化趋势分析 总被引：69，自引：11，他引：58
使用NCEP/NCAR1958%D2000年再分析格点资料,分析了西北地区空中水汽和水汽输送的时空分布特征和变化趋势.结果表明:1)西北地区空中水汽地域分布主要集中在西北地区东部和西部的天山北部以及塔里木河流域盆地,而西北地区中部水汽含量较少,尤以青海的西部和北部为最;2)西北地区空中水汽主要来自印度洋孟加拉湾、南海以及阿拉伯海的水汽输送,北面还有一支来自西伯利亚和蒙古方向的水汽输送;3)西北地区空中水汽含量自50年代末至80年代中期呈明显下降趋势,而从80年代后期开始水汽又呈波动上升趋势.水汽增加地区主要在新疆北部沿河西走廊至甘肃中部祁连山区中段以及南疆盆地西部,而其它地区近年来水汽明显减少,其中减少幅度最大的地方位于西北中部的甘肃、青海、新疆交界处以及东部的陕西省;4)从空中水汽年代际变化趋势看,60～70年代西北大部分地区呈现减少趋势,而80～90年代全区普遍呈现增多趋势,以西北地区西部水汽增多趋势最为明显.最后讨论了影响西北地区水汽分布及输送的气候动力因子. 相似文献
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20世纪西北地区降水量变化特征 总被引：143，自引：17，他引：126
利用英国东安哥拉大学气候研究中心(CRU)的Hulme最新的1900-1998年的全球降水量资料,分析了20世纪西北地区降水量的变化特征.结果表明,20世纪西北地区降水量处于下降通道中,后期略有回升;西北地区东部和西部降水量的年代际变化有相反的趋势;20世纪后期西北地区中西部降水量有明显的增多趋势,东部降水量持续偏少,干旱连年发生. 相似文献
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中国东部土壤温度、湿度变化的长期趋势及其与气候背景的联系 总被引：14，自引：0，他引：14
利用1971-2000年中国722站逐月的土壤温度资料和1981-1998年178站逐旬的土壤湿度观测资料,分析了中国东部土壤温度、湿度变化的长期趋势及其与气温、降水变化的关系.结果表明:①我国东部土壤温度的变化在年际一年代际时间尺度上存在明显的区域性差异,其中东北地区表现为持续上升型,而西北东部一华北、江淮和西南一华南地区均为先降后升型;②1970-2000年代,土壤温度的变化在东北以及西北东部一华北地区有显著的上升趋势,而在江淮和西南一华南地区,总体而言变化趋势不显著.此外,1980-1990年代,各区域土壤湿度的变化趋势均不显著;③在年际一年代际尺度上,各区域土壤温度和气温的变化具有显著的正相关关系,而土壤湿度与土壤温度的变化普遍呈负相关关系,其中尤以西北东部-华北地区最为显著.而在较长的时间尺度上,土壤湿度与降水的变化仍然存在较好的正相关关系. 相似文献
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利用1971-2010年青海省境内43个气象站的降水量和水汽压月资料, 运用整层大气可降水量经验公式, 计算了青海高原东部农业区、环青海湖区、三江源区和柴达木盆地4个不同生态功能区的可降水量和降水转化率. 结果表明: 不同生态功能区可降水量均呈单峰形态分布, 均在夏季达到最大值; 降水转化率在三江源区和东部农业区呈双峰分布, 柴达木盆地和环青海湖地区呈单峰分布. 不同生态功能区年可降水量近40 a均呈上升趋势, 其中, 柴达木盆地和环青海湖区上升趋势显著; 不同生态功能区年可降水量均发生了突变, 东部农业区发生在1983年, 柴达木盆地发生在1996年, 三江源区和环青海湖区发生在1993年. 可降水量自西向东呈逐渐增加趋势, 降水转化率形成以青海湖区为中心的马鞍形场. 相似文献
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利用美国国家环境保护委员会/国家大气研究中心(NCEP/NCAR)再分析气候资料,分析了西风带与季风对我国西北地区水汽输送的作用。分析表明,大气水汽输送在西北地区的3个分区特征非常明显:高原切变线以南,主要是来自西南季风的水汽输送;高原切变线以北,主要是来自西风带的水汽输送;高原切变线向东北方向的延长部位是一鞍型区,为西风带与西南季风的共同影响区。青藏高原东部的西南季风气流有绕行和向北翻越青藏高原的水汽输送;而在青藏高原中西部地区,主要是由青藏高原周边向主体的水汽输送,没有明显的翻越青藏高原的水汽输送。在青藏高原以北的大部分地区以对流层中层的水汽输送为主;在青藏高原南部以低层水汽输送为主。在青藏高原以北的大部分地区,水汽输送为辐散,即输入的水汽又被扩散出去了;在青藏高原主体和我国西北地区东部为水汽输送的辐合区。西风带的水汽输送为我国西北大部分地区提供了基本的水汽来源,西风变化对其水汽输送通量散度年际变化有直接的作用;南亚夏季风通过西南季风气流水汽输送直接影响我国西北地区南部和东部,并且,其变化通过环流结构调整影响西风带的波动,进而影响西风带对西北地区的水汽输送。 相似文献
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利用1982—2006年的GIMMS-NDVI数据,应用RS与GIS技术,结合水资源的形成与转化规律分析了准噶尔盆地植被的时空演化特征与水文地质因素的关系。结果表明:植被指数较高地区分别对应径流消耗和强烈转化区及径流形成区,即平原绿洲和山区林草地;植被指数较低地区主要为荒漠生态系统,即缺水区。研究区植被指数年际变化整体呈弱增加趋势,与降水的相关性存在明显的地域分异特性,与海拔700~1 650 m的低山半荒漠和砾质戈壁地区相关性最大。植被指数空间变化呈现明显的地域分异特性,径流形成区NDVI显著减少,主要为山区林草地;径流消耗与强烈转化区和径流排泄蒸散区NDVI显著增加,主要为人工绿洲。以典型剖面为例,径流变化与植被显著增加的山区荒漠和绿洲生态系统的NDVI变化呈显著正相关,体现为冰川雪地转化为荒漠,平原林草地、水域和荒漠转化为耕地;径流变化与植被显著减少的山地生态系统中的山区林草地的NDVI变化呈显著负相关,山地生态系统涵养水资源的能力下降。研究成果可为干旱半干旱区生态环境治理及水资源开发利用提供依据。 相似文献
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近50a西北地区年径流变化反映的区域气候差异 总被引：10，自引：6，他引：4
应用我国西部主要河流1951-2000年年径流资料,分析径流变化的区域特征.结果表明:中国西部地区大部分河流径流呈增加趋势,特别是天山南坡逐河流增加最为显著,最高达14%·(10a)-1,其年径流的变化过程相关分析和差积曲线显示,西北地区西部新疆地区与东部的黄河上游年径流变化呈反相变化特征,而西北地区东部河流径流变化则与黄河上游的径流呈正相关关系.西北地区东部黄河年径流和西北太平洋夏季季风指数及其差积曲线表现出一致的变化过程,这表明了黄河上游径流变化主要受东亚季风的影响,同时由于东亚季风与西风在西北地区的相互作用,间接的影响到了新疆地区的径流和降水.这从一个侧面反映的西风带、东亚季风和高原季风的相互作用. 相似文献
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1981-2006年西北干旱区NDVI时空分布变化对水热条件的响应 总被引：5，自引：1，他引：4
气候是植被变化的重要驱动因子. 利用1981-2006年GIMMS归一化植被指数（NDVI）时间序列数据,结合68个气象站降水、气温数据和DEM地形数据等资料,研究分析了西北干旱区植被活动的年、季变化和空间差异. 结果显示：在1981-2006年的26 a,西北干旱区植被的覆盖率增加了4.5%,年平均NDVI增加了3.2%;植被的生长季延长,主要表现在生长季的推迟. 从总体来说,植被覆盖率、生长季和NDVI值在2000年以前显著增加,而在2000年以后都呈现减小的趋势;其中,减少明显的区域是在伊犁河谷、中天山及平原区,在河流上游山区或源头以及部分河流两岸呈现增加态势;在年际变化上,大部分区域的气温、降水与NDVI相关性不强. 而年平均气温在4.58 ℃以下低温区和年降水在180 mm以上的相对湿润区,气温和降水都呈现正相关;在季节变化上,NDVI值在春季和秋季与温度相关显著,而夏季与降水相关性强. 2000年以后,植被覆盖率和NDVI值开始出现降低趋势与气温持续升高、降水量增幅下降有关. 相似文献
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The relationship between drought activity and vegetation cover in Northwest China from 1982 to 2013 总被引：1，自引：0，他引：1
Yelin Jiang Ranghui Wang Qing Peng Xiaoquan Wu Husen Ning Cheng Li 《Natural Hazards》2018,92(1):145-163
We investigated drought activity and the relationship between drought and vegetation in Northwest China over the period 1982–2013 using the standardized precipitation evapotranspiration index (SPEI) and the normalized difference vegetation index (NDVI). The indexes were, respectively, calculated from ground-based meteorological data and from remotely sensed satellite data. The spatial and temporal distributions of drought (SPEI) and of vegetation cover (NDVI) were compared using annual trends, and the relationships between these trends were analyzed. The results are: (1) Overall, Northwest China had a drought trend during the study period, although some a few regions show a significant wetness trend; (2) the mean annual NDVI fluctuates, but overall shows an increasing trend, particularly in some mountainous areas that have at least adequate water and vegetation cover, while unused land becomes degraded; (3) most regions show a positive correlation between SPEI and NDVI, although the western parts of the Tarim basin, Qaidam basin, and some regions in the southeastern part of study area show a negative correlation; and (4) the various regions respond differently to global climate change, but in general regions with more vegetation cover show increased vegetation growth, while regions with less vegetation cover are becoming degraded and thus more vulnerable to the adverse effects of climate change. 相似文献
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青藏高原高寒草地植被指数变化与地表温度的相互关系 总被引：3，自引：1，他引：2
为了解脆弱的高原生态环境对升温过程的响应, 利用1982-2006年国家标准地面气象站地表温度和GIMMS-NDVI数据集, 探讨了青藏高原高寒草地植被指数和地表温度的变化特征及其相互关系. 结果表明:1982-2006年, 高寒草地NDVI、地表温度整体均呈现增加趋势, 年均NDVI、生长季NDVI、年最大NDVI(NDVImax)与年均地表温度、生长季地表温度的上升趋势分别为0.007 (10a)-1、0.011 (10a)-1、0.007 (10a)-1与0.60 ℃·(10a)-1、0.43 ℃·(10a)-1; NDVImax与地表温度显著相关的地区达70.49%. 但是高原地形、气候、水文环境的空间差异性导致高寒草地NDVI与地表温度的相关关系十分复杂. NDVImax与年均地表温度的相关性最为显著; 在返青期和枯萎期, NDVI与地表温度均为显著正相关. 不同的植被覆盖条件下, NDVI对地表温度的响应不同:植被覆盖差以及退化严重的地区, NDVImax与地表温度呈负相关性; 反之, NDVImax与地表温度主要表现为正相关. 相似文献
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基于遥感和地理信息系统技术,利用NOAA-AVHRR数据对我国最近18年(1982～1999)来的植被覆盖的动态变化进行了分析.结果表明:我国植被覆盖的动态变化受气候波动的影响十分显著,并且这种变化的区域性差异明显.18年来,NDVI减小的地区主要分布在西北地区和青藏高原,而NDVI增加的地区主要发生在东部地区;20世纪80年代和90年代的NDVI变化趋势之间存在较大差异;90年代NDVI减小的区域明显地比80年代增加,特别是西北干旱地区NDVI的下降趋势明显.我国珠江三角洲和长江三角洲地区是18年来植被覆盖下降趋势最明显的地区,表明快速城市化的影响. 相似文献
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Assessing vegetation dynamics in the Three-North Shelter Forest region of China using AVHRR NDVI data 总被引：1，自引：1，他引：0
Hanchen Duan Changzhen Yan Atsushi Tsunekawa Xiang Song Sen Li Jiali Xie 《Environmental Earth Sciences》2011,64(4):1011-1020
The Three-North Shelter Forest Programme (TNSFP) covers 551 Chinese counties and an area of 4,069,000 km2 mostly in arid and semi-arid regions. In this paper, we discuss the temporal and spatial changes in value of the normalized-difference
vegetation index (NDVI) in this region, and the relationships between NDVI and climatic factors (temperature and precipitation)
based on NOAA Advanced Very High Resolution Radiometer Global Inventory Modeling and Mapping Studies NDVI data with 8-km resolution
from 1982 to 2006. During the past 25 years, the vegetation cover has generally increased in eastern regions of China and
the oasis in the north piedmont of Tianshan Mountains, but has decreased northwest of Xinjiang and in the Hulunbeier Plateau.
The multi-year monthly average NDVI distribution map showed that NDVI increased from April to August, but in the western and
northern plateau areas, the lower temperatures and high altitude created a shorter growing season (1 or 2 months). The vegetation
of the study area has generally increased in the regions covered by the TNSFP. Linear regression analysis of the vegetation
cover showed an increasing trend over large areas. The largest annual growth rate per pixel (the slope of the regression)
was 0.009; the largest negative annual change was −0.004. The correlation between NDVI and precipitation was higher than that
between NDVI and temperature, suggesting that precipitation is the most important factor that affects NDVI changes in the
study area, especially for temperate desert vegetation in northwestern China. 相似文献
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The water resource and its change of mountainous area are very important to the oasis economic system and ecosystem in the arid areas of northwest China. Accurately understanding the water transfer and circulation process among vegetation, soil, and atmosphere over different hydrological units in mountainous areas such as snow and ice, cold desert, forest and grassland is the basic scientific issue of water research in cold and arid regions, which is also the basis of water resource delicacy management and regulation. There are many research results on the hydrological function of different land covers in mountain areas, basin hydrological processes, however, there are only very limited studies on the water internal recycle at basin scale. The quantitative study on the mechanism of water internal recycle is still at the starting stage, which faces many challenges. The key project “Study on water internal recycle processes and mechanism in typical mountain areas of inland basins, Northwest China” funded by National Natural Science Foundation of China will select the Aksu River and Shule River Basin, which have better observation basis, as study area. The internal mechanism of moisture transfer and exchange process of different land cover and atmosphere, the internal mechanism of water cycle in the basin, and water transfer paths in atmosphere will be studied through enhancing runoff plot experiments on different land cover, analyzing the mechanism of water vapor transfer and exchange between different land covers in the watershed by isotope tracing on the water vapor flux of vegetation water, soil moisture and atmospheric moisture, improving the algorithms of remote sensing inversion and ground verification on land surface evapotranspiration on different land cover, and analyzing the water vapor flux from reanalysis data, and the coupling modeling of regional climate model and land surface process model. At last, the effect of different land cover in hydrological process of mountain area, and the impact of land cover on downstream oasis will be systematically analyzed. 相似文献
18.
Trends and variation in vegetation greenness related to geographic controls in middle and eastern Inner Mongolia,China 总被引：1，自引：1，他引：0
Extensive studies have investigated the relationships between climate change and vegetation dynamics. However, the geographic
controls on vegetation dynamics are rarely studied. In this study, the geographic controls on the trends and variation of
vegetation greenness in middle and eastern Inner Mongolia, China (mid-eastern Inner Mongolia) were investigated. The SPOT
VEGETATION 10-day period synthesis archive of normalized difference vegetation index (NDVI) from 1999 to 2007 was used for
this study. First, the maximum value compositing (MVC) method was applied to derive monthly maximum NDVI (MNDVI), and then
yearly mean NDVI (YMNDVI) was calculated by averaging the MNDVIs. The greenness rate of change (GRC) and the coefficient of
variation (CV) were used to monitor the trends and variation in YMNDVI at each raster grid for different vegetation types,
which were determined from a land use dataset at a scale of 1:100,000, interpreted from Landsat TM images in 2000. The possible
effects of geographic factors including elevation, slope and aspect on GRC and CV for three main vegetation types (cropland,
forest and steppe) were analyzed. The results indicate that the average NDVI values during the 9-year study period for steppe,
forest and cropland were 0.26, 0.41 and 0.32, respectively; while the GRC was 0.008, 0.042 and 0.033 per decade, respectively;
and CVs were 10.2, 4.8 and 7.1%, respectively. Cropland and steppe shared a similar trend in NDVI variation, with both decreasing
initially and then increasing over the study period. The forest YMNDVI increased throughout the study period. The GRCs of
the forest also increased, although GRCs for cropland and steppe decreased with increasing elevation. The GRCs of cropland
and steppe increased with increasing slope, but the forest GRCs were not as closely related to slope. All three vegetation
types exhibited the same effects in that the GRC was larger on north-facing (shady) slopes than south-facing slopes due to
differences in water conditions. The CVs of the three vegetation types showed different features to the GRC. The CVs for all
three vegetation types were not affected by aspect. The CVs for forest and cropland showed minor effects with changes in elevation
and slope, but the CV for steppe decreased with increasing slope, and increased with increasing elevations to 1,200 m, before
decreasing at higher elevations. Our findings suggest that the role of geographic factors in controlling GRC should also be
considered alongside climate factors. 相似文献
19.
Shulin Liu Tao Wang Jian Guo Jianjun Qu Peijun An 《Environmental Earth Sciences》2010,60(7):1459-1466
Dynamic change of vegetation in northern China from 1998–2007 was explored, based on SPOT-VGT data. The results showed that
the NDVI can effectively monitor vegetation change, but also the mean multi-year NDVI maximum of 0.10 basically can be considered
as the threshold of vegetation cover in northern China, and those places with smaller than or equal to the threshold value
mainly were covered by deserts, Gobi and lakes, salinization lands, glaciers, snow patches and bare mountains, etc. The change
trends of vegetation where sub-region C and D were affected by east-Asia monsoon were similar with the characteristics of
first decreasing, later increasing and finally slowly decreasing; the difference lies in that sub-region C maintained a lower
vegetation state, and sub-region D reached a higher state. The vegetation change of sub-region A was anomalous with smaller
fluctuation. The change trend of vegetation of sub-region B was not only extremely unstable, but also the change extent was
huge. As far as the whole of northern China is concerned, vegetation has not demonstrated obvious improvement since these
ecological construction and protection projects, and the area of vegetation degradation still is much larger than that of
vegetation improvement from 1998 to 2007, but there was a bigger spatial difference. Field investigation and remote sensing
monitoring reveal that vegetation has obviously been improved in the agro-grazing mixing zone and to the south, as well as
many oases in the northwestern arid zone, while vegetation still has worsened in the steppes, especially the Ulanqab steppe,
Hunshandake Sandy Land, the region along the Sino–Mongolia border within Xilingol Meng, Hulunbeir Sandy Land and the northern
Tianshan mountain region in Xinjiang. Human activities only obviously showed success in local regions. The compelling challenges
of restoring the eco-environment are still immense, especially in the northern grazing zone of China. 相似文献
20.
为了解森林退化的原因,利用2000-2015年的MODIS NDVI数据,在分析贵州省植被变化趋势的基础上识别了归一化植被指数（NDVI)显著下降的区域,并在NDVI显著下降区选取面积大于10 km2的森林图斑为兴趣区,分析其内气候变化趋势及对森林NDVI值的影响。研究表明:197个兴趣区主要分布在贵州省西北部的赤水—习水、东北部的梵净山和东南部的非喀斯特区域;区内春、夏季NDVI变化趋势与年NDVI值变化趋势一致,下降速率达到-0.01·yr-1,冬季与其他季节变化趋势相反,呈不显著升高趋势;区内春季和夏季气温升高显著,降水和日照时间无明显变化,整体气候变化呈暖干趋势;夏季温度升高是NDVI降低的主要驱动因素。 相似文献