新疆气候“湿干转折”的信号和影响探讨

新疆是对全球变化响应最敏感地区之一,分析全球变暖背景下新疆干湿气候变化及其影响,对应对和适应未来气候变化带来的影响具有重要意义。基于气象水文观测资料,对新疆区域干湿气候变化及其影响评估进行了探讨。结果表明：① 20世纪80年代中后期以来新疆气温升高,降水量增加,呈“暖湿化”特征;但1997年之后,干旱变化趋势、干旱频率、干旱发生月份等均有明显增加,导致70%以上的区域变干,新疆气候出现了从“暖湿化”向“暖干化”转折的强烈信号,即发生了“湿干转折”;② 新疆气候转折对区域生态和水资源造成明显的影响,归一化植被指数（Normalized Difference Vegetation Index, NDVI）经历了先增后减的变化过程,1982—1997年植被趋于“变绿”,但1997年之后植被长势迟滞,土壤水分明显下降,生态逆转,生态负效应凸显;③ 新疆河流径流变化出现明显的区域差异,对干湿气候转折响应复杂,受冰雪融水对径流补给比例的影响,发源于天山的河流径流对区域干湿变化有正响应,但发源于昆仑山的河流径流响应不明显。研究结果表明气候“湿干转折”和极端气候事件加剧背景下新疆干旱化急剧增加,水循环系统和生态系统不稳定性加剧,相关成果可为区域干旱灾害防灾减灾和风险管理提供有价值的决策参考。     

新疆极端降水的气候变化

采用1961～2000年55个气象台站的逐日降水观测资料,分析近40年来新疆极端降水的气候变化、发展趋势和空间分布差异。用Mann-Kendall法对年极端降水量进行突变检验。研究表明：(1) 只有天山北麓经济带和天山南麓国家级棉花基地阿克苏地区极端降水量和频次有显著增多,尤以80年代以后明显,年极端降水量于1980年发生了气候突变,这种气候变化是由夏半年极端降雨量和频次增多导致的。(2) 新疆极端降水强度无显著变化,极端降水频次的显著增多导致极端降水量的显著增多。(3) 极端降水对年总降水量的贡献天山山区占年降水量的41.9%,北疆北部与和田区域极端降水的贡献为17.2%和21.9%,其它区域在25%~31.3%。年极端降水量距平与年降水量距平有好的相关关系 (除阿克苏地区和焉耆盆地外),说明极端降水量的变化导致年降水量的变化。     

新疆夏季0 oC 层高度变化对河流年径流量的影响

按气候特点和河流径流情况把新疆划分为阿尔泰- 塔城、天山山区和昆仑山北坡3 个研究区域。采用1960~2002 年新疆12 个探空站逐日观测资料和34 个水文站的年径流资料, 利用经过5 点平滑处理的曲线趋势对比和线性相关的研究方法, 定性与定量相结合分析了43 年来新疆夏季0 ^oC 层平均高度变化和河流径流变化趋势及空间分布差异, 并建立了二者的定量关系式。研究表明: 新疆夏季0 ^oC层平均高度与河流年径流量变化具有较好的一致性, 尤其是1970 年代以来, 两者的变化趋势更加亦步亦趋。各区变化不尽相同, 阿尔泰- 塔城和天山山区为1990 年代初以来夏季0 ^oC层平均高度为显著升高地区, 昆仑山北坡为下降区。与之相对应, 同期前两个地区的河流径流量也显著增大, 后一个区域的径流量略为减少。就相关 性而言, 新疆全区和分区的天山山区以及昆仑山北坡等地的夏季0 ^oC层高度与河流径流量均有较好的相关性, 均通过了0.01 显著水平的统计检验。表明新疆近年来不仅近地面发生了气候变化, 高空也同样发生了类似的变化, 并直接导致了夏季0 o^oC层高度的升降。气候变暖, 新疆夏季0 ^oC层升高, 山区的冰雪消融加快, 河流径流量相应增多, 进入丰水期。反之, 进入枯水期。夏季0 ^oC层高度的升降直接影响新疆河流径流量, 在新疆气候暖湿化过程中, 高空的增温也是一个较直接的因子。     

Hydrology and water resources variation and its response to regional climate change in Xinjiang

Based on the surface runoff, temperature and precipitation data over the last 50 years from eight representative rivers in Xinjiang, using Mann-Kendall trend and jump detection method, the paper investigated the long-term trend and jump point of time series, the surface runoff, mean annual temperature and annual precipitation. Meanwhile, the paper analyzed the relationship between runoff and temperature and precipitation, and the flood frequency and peak flow. Results showed that climate of all parts of Xinjiang conformably has experienced an increase in temperature and precipitation since the mid-1980s. Northern Xinjiang was the area that changed most significantly followed by southern and eastern Xinjiang. Affected by temperature and precipitation variation, river runoff had changed both inter- annually and intra-annually. The surface runoff of most rivers has increased significantly since the early 1990s, and some of them have even witnessed the earlier spring floods, later summer floods and increasing flood peaks. The variation characteristics were closely related with the replenishment types of rivers. Flood frequency and peak flow increased all over Xinjiang. Climate warming has had an effect on the regional hydrological cycle.     

气候变暖对新疆降水和径流影响分析

全球气候变暖对新疆气候产生了较大的影响，在升温的背景下从20世纪80年代以来本区的降水量、冰川储量、地表径流、地下水资源发生了较大的变化：全区降水总量增加，冰川物质平衡以负平衡为主，局部地区地表径流量明显增加。对比分析不同地区降水量的变化情况，发现新疆不同地区的降水量变化情况存在明显差异，且尚难判断全区降水量是否有稳定增加的趋势。通过对已有资料的分析计算，对比冰川加速消融和降水量增加对本区地表径流增大的贡献，表明引起局部地区地表径流显著增加的主要原因是冰川加速消融。气候变暖打乱了本地的水平衡，使本地洪水和干旱灾害有加剧趋势。     

新疆水文水资源变化及对区域气候变化的响应

Based on the surface runoff, temperature and precipitation data over the last 50 years from eight representative rivers in Xinjiang, using Mann-Kendall trend and jump detection method, the paper investigated the long-term trend and jump point of time series, the surface runoff, mean annual temperature and annual precipitation. Meanwhile, the paper analyzed the relationship between runoff and temperature and precipitation, and the flood frequency and peak flow. Results showed that climate of all parts of Xinjiang conformably has experienced an increase in temperature and precipitation since the mid-1980s. Northern Xinjiang was the area that changed most significantly followed by southern and eastern Xinjiang. Affected by temperature and precipitation variation, river runoff had changed both inter-annually and intra-annually. The surface runoff of most rivers has increased significantly since the early 1990s, and some of them have even witnessed the earlier spring floods, later summer floods and increasing flood peaks. The variation characteristics were closely related with the replenishment types of rivers. Flood frequency and peak flow increased all over Xinjiang. Climate warming has had an effect on the regional hydrological cycle.     

新疆河流径流量三十余年来的变化

本文利用新疆河流地表径流量统计资料，分析了全疆范围地表径流量３０多年来的年际变化，年内变化以及引起水量变化的原因。     

新疆水文水资源变化及对区域气候变化的响应

基于全疆8条代表性河流近50年的地表径流、气温和降水数据,采用Mann-Kendall趋势检验和突变检测法,对各条河流地表径流、年均气温和年降水进行了长期趋势检验和突变滗分析,同时对径流与气温、降水之间的变化关系以及水文极端事件洪水的发生频次和洪峰流量进行了分析.结果表明,20世纪80年代中期以来伞疆各地气候一致表现为气温升高和降水增多,其中北疆地区变化最为显著,南疆其次,东疆最小.受气温、降水变化影响,河流径流发生年际和年内分布变化.大部分河流自20世纪90年代初水量显著增多,有春汛提前、夏汛推后和洪峰流量增大的现象,其变化特征与河流补给类型密切相关.全疆洪水发生频次增多、洪峰流最增大.气候变暖已对区域水文循环产生重要影响.     

Climate transformation to warm-humid and its effect on river runoff in the source region of the Yellow River

The change characteristics and trends of the regional climate in the source region of the Yellow River, and the response of runoff to climate change, are analyzed based on observational data of air temperature, precipitation, and runoff at 10 main hydrological and weather stations in the region. Our results show that a strong signal of climate shift from warm-dry to warm-humid in the western parts of northwestern China （Xinjiang） and the western Hexi Corridor of Gansu Province occurred in the late 1980s, and a same signal of climate change occurred in the mid-2000s in the source region of the Yellow River located in the eastern part of northwestern China. This climate changeover has led to a rapid increase in rainfall and stream runoff in the latter region. In most of the years since 2004 the average annual precipitation in the source region of the Yellow River has been greater than the long-term average annual value, and after 2007 the runoff measured at all of the hydrologic sections on the main channel of the Yellow River in the source region has also consistently exceeded the long-term average annual because of rainfall increase. It is difficult to determine the prospects of future climate change until additional observations and research are conducted on the rate and temporal and spatial extents of climate change in the region. Nevertheless, we predict that the climate shift from warm-dry to warm-humid in the source region of the Yellow River is very likely to be in the decadal time scale, which means a warming and rainy climate in the source region of the Yellow River will continue in the coming decades.     

The response of annual runoff to the height change of the summertime 0℃ level over Xinjiang

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960–2002, the variance of the summertime 0℃ level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0℃ level height in Xinjiang correlates well with that of the annual river runoff, especially since the early 1990s, but it differs from region to region, with both the average height of the 0℃ level and runoff quantity significantly increasing over time in the Altay- Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0℃ level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0℃ level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

新疆河流年径流量对夏季0C层高度变化的响应

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960-2002, the variance of the summertime 0℃ level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0℃ level height in Xinjiang correlates well with that of the annual river runoff,especially since the early 1990s, but it differs from region to region, with both the average height of the 0℃ level and runoff quantity significantly increasing over time in the Altay-Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0℃ level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0℃ level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

宁夏植被覆盖动态变化及与气候因子的关系

利用1999-2009年的SPOT-VGT NDVI数据,计算出宁夏近11 a来的植被覆盖度,对其变化特征进行了研究,结合同期气象观测资料,从空间上分析了植被覆盖度与区域气候因子之间的关系。结果表明,南部六盘山区和北部引黄灌区植被覆盖度高,而中部干旱带等地区的植被覆盖度较低,但中部干旱带却有较高的绝对变化率;从时间变化来看,近11 a来宁夏大部分地区的植被覆盖度在逐年增加。植被覆盖度的变化与气候因子有关,除引黄灌区和六盘山林区外,中部干旱带等地的植被覆盖度与降水呈正相关,区域气候的干湿波动,影响了植被覆盖度的高低;在有灌溉保障条件的农业垦殖区,植被覆盖度还与气温呈正相关,即有效积温的增加,会促进农作物生长,从而导致区域植被的覆盖度提高。     

2000-2012年祁连山植被覆盖变化及其与气候因子的相关性

研究祁连山地区植被覆盖变化及其与气候因子的响应关系对这一地区土地利用总体特征以及对区域及全球气候和环境变化都将产生深远的意义。利用2000-2012年美国国家航空航天局提供的MODIS NDVI数据并结合相应的气候资料,通过对逐像元信息的提取和分析,运用均值法、斜率分析法、相关分析法,研究了2000-2012年不同季节祁连山植被覆盖的时空变化及其与气候因子的相关性。结果表明:13 a来祁连山植被覆盖整体上呈增加趋势,其中春季植被改善最为明显,秋季次之;植被覆盖变化在不同季节都存在明显的空间差异;不同季节植被与气温、降水的时滞效应不尽相同;祁连山春季大部分地区NDVI与气温呈显著正相关,夏季NDVI与降水呈显著正相关,秋、冬季NDVI与降水、气温的相关性不明显。     

Assessment of meteorological disasters based on information diffusion theory in Xinjiang,Northwest China

Data of flood, drought, hailstorms, and low temperature events in Xinjiang from 1949 to 2012 were analyzed with the diffusion method to assess the risk of the most common types of disasters in Xinjiang. It was proved that the frequency and intensity of meteorological disasters of the study area showed an increasing trend associated with global warming. Among the four types of disasters, surpass probability of drought was the largest, followed by hailstorm, low temperature and flood in turn. Moreover, the wavelet method analysis revealed that greater oscillations had occurred since 2000, which may be associated with the occurrence of extreme climatic changes. The spatial distribution of frequencies reveals that the northern slope of Tianshan Mountains is a multiple disaster area, the southern slope of Tianshan is the area where more floods and hailstorms occur, and the west of Turpan-Hami Basin is the area wind is prevalent. The relationships between disaster-affected areas and corresponding meteorological and socio-economic indexes were also analyzed. It indicated that there were significant positive correlations between the areas affected and the most meteorological and socio-economic indicators except the grain acreage.     

气候转暖及人类活动对北疆中小河流降水-径流关系的影响

利用近40 a来的水文气象资料,分析北疆20世纪80~90年代气候转暖及人类活动对北疆不同地区的中小河流降水-径流关系的影响,主要结论如下:①北疆西部的哈拉依灭勒河、卡琅古尔河,在1980年以后气候转暖的背景下,它们的自然降水-径流关系并无明显改变。②北部额尔齐斯河流域东部产流区平均高程较高的大青河,在90年代气候显著转暖的背景下,其自然降水-径流关系并无明显改变;而位于大青河东侧、流域平均高程较低、山区流域降水量较小的小青河,在90年代气候明显转暖的背景下,其自然降水径流关系发生了变化,所形成的自然地表径流量明显减少。③天山中部北坡的乌鲁木齐河,在80~90年代气候转暖的背景下,其自然降水-径流关系发生了变化,产流量明显偏多。④天山东部北坡的开垦河,在80~90年代气候转暖及人类活动影响的背景下,其自然降水-径流关系发生了变化,产流量减少。⑤乌鲁木齐近郊低山丘陵区的水磨河,在近40 a来的增温及人类活动影响的背景下,其自然降水-径流关系发生了变化,尽管乌鲁木齐年降水量有增加趋势,而其径流却是减少的。     

1999—2010年中国西北地区植被覆盖对气候变化和人类活动的响应

中国西北地区气候干旱,频繁出现沙尘天气,属于生态脆弱区域,而植被变化是生态系统对气候变化响应的指示器,研究其变化对改善西北生态环境具有重要意义.本文利用1999—2010年归一化植被指数(NDVI)以及气象数据研究中国西北地区植被覆盖时空变化,以Sen趋势度结合Mann-Kendall检验、相关和偏相关分析以及残差法分析人类活动和气候变化对植被覆盖变化的影响.结果表明:西北地区植被覆盖整体呈增加趋势,但在局部地区气候干旱少雨和人类活动抑制植被生长.植被变化强度空间差异是人类活动和气候要素共同作用的结果:气温高,降水少,大部分地区植被覆盖与气候要素相关显著,并且植被变化对气温和降水的响应存在一定滞后时间;蒸发量大于降水量,人类引水灌溉弥补降水不足,使得农业植被呈增长趋势.新疆北部地区植被覆盖呈下降趋势,原因是气候干旱、沙漠化严重会抑制植被生长,人类活动频繁、城市扩建同样会破坏植被生长.     

The response of annual runoff to the height change of the summertime 0°C level over Xinjiang

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960–2002, the variance of the summertime 0°C level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0°C level height in Xinjiang correlates well with that of the annual river runoff, especially since the early 1990s, but it differs from region to region, with both the average height of the 0°C level and runoff quantity significantly increasing over time in the Altay-Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0°C level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0°C level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

A study on environmental aridity over northern and southern to Qinling Mountains under climate warming

1 Introduction With progressive researches on global climate change, an integrated study of various disciplines tends to be inevitable. Mr. Moore III, chairman of IGBP, holds that the key to integration is to synthesize scientific findings so as to get new ideas and to chance cognition up to a new high[1]. Micro-study, rather than macro-study focuses on regional change[2-5]. To strengthen the global perspective in the study, "to research on typical regions and to deepen the regional divide…     

A study on environmental aridity over northern and southern to Qinling Mountains under climate warming

Based on the data up to 1999 from hydroclimatological departments, this paper analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the grades of dryness/wetness (GDW) in 100 years show that the northern region has entered a drought period, while the southern is a humid period. In a course of ten years, the D-value of annual average air temperature over southern Shaanxi (the Hanjiang Valley) and the Central Shaanxi Plain (the Guanzhong Plain) has narrowed, i.e., the former with a slight change and the latter with rapid increase in temperature. Both regions were arid with the decrease in precipitation D-value, namely the plain became warmer while the south was drier. The Qinling Mountains play a pronounced role in the climatic divide. The runoff coefficient (RC) of the Weihe River decreases synchronously with that of the Hanjiang due to climate warming. The RC of Weihe dropped from 0.2 in the 1950s to less than 0.1 in the 1990s. The Weihe Valley (the Guanzhong Plain) is practically an arid area due to shortage of water. The successive 0.5, 1.0 oC temperature anomaly over China marks, perhaps, the important transition period in which the environment becomes more vulnerable than before.The study shows the obvious trend of environmental aridity, which is of help to the understanding of regional response to global climate change.     

Correlation analysis between vegetation coverage and climate drought conditions in North China during 2001–2013

Climate change is one of the most important factors that affect vegetation distribution in North China. Among all climatic factors, drought is considered to have the most significant effect on the environment. Based on previous studies, the climate drought index can be used to assess the evolutionary trend of the ecological environment under various arid climatic conditions. It is necessary for us to further explore the relationship between vegetation coverage (index) and climate drought conditions. Therefore, in this study, based on MODIS-NDVI products and meteorological observation data, the Palmer Drought Severity Index (PDSI) and vegetation coverage in North China were first calculated. Then, the interannual variations of PDSI and vegetation coverage during 2001–2013 were analyzed using a Theil-Sen slope estimator. Finally, an ecoregion perspective of the correlation between them was discussed. The experimental results demonstrated that the PDSI index and vegetation coverage value varied over different ecoregions. During the period 2001–2013, vegetation coverage increased in the southern and northern mountains of North China, while it showed a decreasing trend in the Beijing-Tianjin-Tangshan City Circle area and suburban agricultural zone located in Hebei Province and Henan Province). Over 13 years, the climate of the northeastern part of North China became more humid, while in the southern part of North China, it tended to be dry. According to the correlation analysis results, 73.37% of North China showed a positive correlation between the vegetation coverage and climate drought index. A negative correlation was observed mainly in urban and suburban areas of Beijing, Tianjin, Hebei Province, and Henan Province. In most parts of North China, drought conditions in summer and autumn had a strong influence on vegetation coverage.