西北干旱区大气水分循环要素变化研究进展

西北干旱区是对全球气候变化响应最敏感的地区之一。全球变暖加剧水循环,引起大气水分循环要素发生明显变化。借助最新资料对过去50 a西北干旱区大气水分循环要素变化特征和相关科学问题进行了梳理总结,其主要结论:(1)西北干旱区水汽和降水量有一致性变化趋势,在20世纪80年代中后期突变型增多,21世纪初有微弱的减小态势。受季风强度减弱的影响,西北东部地区水汽和降水量减小明显。(2)降水量增加站点占到95.9%,形成了天山、祁连山等增湿中心,具有明显的增湿海拔依赖性特征。(3)实际蒸散发量呈微弱的减小趋势,天山山区明显减少,而祁连山地区明显增加。(4)干旱区西部夏季降水以西风带水汽输送为主,但大尺度大降水过程发生时,低纬水汽输送尤为重要。全球气候变暖在影响着大气水分循环要素明显变化的同时,也加剧了干旱区水循环过程和水资源的不确定性。     

新疆北部地区春夏季干旱的区域性和持续性特征

基于1961-2007年36站的逐日降水资料,分析新疆北部地区春、夏季干旱的区域性和持续性特征。结果表明：新疆北部春、夏季干旱发生较为频繁,尤其在北疆西北部地区,春旱平均3 a一遇,夏旱为4~5 a一遇。季节间的连旱概率较低,不足10%,主要以月际间的连旱为主,其中2个月的持续干旱次数占干旱总次数的20%左右。进一步的分析表明,春夏之交的5~6月,是2个月连续干旱发生次数相对频繁的时期,北疆西北部地区此类连续干旱事件最多。伊犁河谷、北天山地区和北疆北部春旱较夏旱频繁,春旱以北疆北部发生最多;夏旱3个区域发生频次相似,但北天山地区大旱发生频数较高。3个区域的春、夏季干旱程度均呈减弱趋势,春旱在20世纪90年代中后期、夏旱在80年代中后期处在一个较低的发生期。     

近51年新疆S干旱指数变化特征分析

利用新疆地区52个气象站1960-2010年月降水量和无雨日数资料,定义了S干旱指数,采用EOF、REOF、Morlet小波分析、Mann-Kendall分析、分布函数等方法,分析了近51年来新疆干旱指数的时空分布特征。结果表明:EOF分解得出,新疆干旱指数存在三种主要的空间分布,即全区一致变化型、南北反向变化型和东西反向变化型;根据REOF前四个旋转荷载向量场高载荷区分布,将新疆干旱指数分成四个区,即新疆北部地区、新疆南部地区、天山中西部地区和天山东部地区;新疆北部地区、天山中西部地区和天山东部地区干旱指数有增大的总趋势,新疆南部地区干旱指数有减小的总趋势。     

基于标准化前期降水蒸散指数的新疆干旱时空演变特征

标准化前期降水蒸散指数(Standardized antecedent precipitation evapotranspiration index,SAPEI)是一种新的日尺度干旱指数,相对标准化降水蒸散指数(SPEI)而言,它不仅考虑当日的降水和蒸散情况,还考虑了早期水分平衡对当天干湿条件的影响,在描述和监测干旱方面更为稳健。本文根据新疆地区42个气象站2000—2019年气象要素数据计算SAPEI,利用线性趋势、M-K检验和反距离插值等方法,研究了21世纪以来新疆地区SAPEI时空变化特征,并基于SAPEI的分区和分代际比较分析了新疆地区干旱强度的时空变化,进而对新疆干旱发生的区域性和广泛程度的四季变化以及不同干旱等级发生频率的空间分布格局进行了探讨。结果表明：新疆气候整体呈湿润化,近年来干湿差异扩大,空间上存在部分相对湿润地区显著变干的现象;新疆春季变干,夏、秋、冬季变湿,夏冬两季在时间和空间上的干湿变化差异截然相反;20年来全疆和分区的干旱强度均显著降低,空间上东北部高、中部和西南部低;新疆干旱范围呈缩减趋势,近年来存在干旱等级提升风险,春季干旱范围扩大;新疆不同干旱等级的发...     

中国西北地区冰雹的气候特征

利用1971-2000年西北185个站3～9月逐月和年冰雹次数,分析了西北冰雹的空间分布特征和时间演变规律.西北年冰雹次数有3个高值中心,一个在青海的曲麻莱,为19.6次,另一个在新疆西部的昭苏,为17.6次,第3个在青海的刚察,为12.7次.185个站冰雹的月变化呈单峰型,主要出现在6～8月.西北185个站冰雹的历年变化呈现出下降的趋势.从春季到秋季,冰雹强中心先起于新疆的昭苏这一中心有很强的持续性.青海南部的冰雹强中心5月在斑马,6月西伸到曲玛莱,7月再西移到托托河,8月东退到清水河,9月又南退到杂多,10月又东退到久治,然后基本消失.     

新疆气候变化影响的观测事实及其对农牧业生产的影响

在近几年新疆气候变化事实的基础上,重点讨论了气候变化对新疆农牧业生产的影响,并有针对性地提出了相应的应对策略。结果表明:虽然目前的一致结论是认为新疆气候是向暖湿转化,即气温升高而降水量增加。但降水量的分布不均,加之春季倒春寒、夏季高温极端天气增加,导致新疆近几年大旱、冰雪的灾害天气频繁出现,对农牧业生产造成不良影响。应对策略主要是要加强水利设施建设,确保旱涝保收。另外要积极采取多种措施防止气候变化给农业带来的负面影响。     

天山山区及周边地区水汽含量的计算与特征分析

利用1976-2009年天山山区周边伊宁、库车和乌鲁木齐3个探空站实测资料,计算逐月平均水汽含量,并建立了与地面水汽压的关系式;利用这个关系式计算了天山山区及周边地区1961-2009年44个站水汽含量,分析了水汽的时空分布特征及其与降水量的关系。结果表明：①天山山区及周边地区水汽含量有3个高值区,主要分布在天山北麓的河谷平原地带和吐鲁番盆地,水汽含量在12~21 mm;南天山及东部的阿克苏地区、库尔勒地区和东天山南部的哈密地区是水汽含量的次高值区,水汽含量在5~13 mm;而中天山和东天山是水汽的低值中心,水汽含量在4~8 mm。② 水汽含量的月际变化呈单峰型,夏季最大,冬季最小,季节变化非常明显;其中2-7月为增长期,3月增长率最大,7月最小,增长率分别为65.8%和17.6%,而8月到次年1月为递减期,12月减少率最大,8月最小,分别为38.5%和7.8%。 天山山区内部月均水汽（7.83 mm）低于全区平均水平(10.51 mm),其中西天山月均和夏季水汽含量均最高,分别为9.88 mm和18.94 mm。③ 49 a间水汽含量年代际变化较小,1986年以后变化波动大且上升趋势明显。④ 水汽和降水量并不具有很好的对应关系,而呈现区域差异。
     

Spatio-temporal patterns of drought in North Xinjiang,China, 1961–2012 based on meteorological drought index

Drought, which is one of the most frequently occurring severe hazards with long time scales and covering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang(NX) shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961–2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter(with rates of –0.26 month/10 a and –15.46%, respectively), and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in "Shihezi-Urumqi-Changji", which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions(severe drought region, moderate drought region and mild drought region), which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOI(Southern Oscillation Index), AOI(Arctic Oscillation Index), AAOI(Antarctic Oscillation Index), PAOI(Pacific/North American Oscillation Index) and NAOI(North Atlantic Oscillation Index) have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer.     

亚洲中部干旱区绿洲水热匹配与生物、农业技术适应性分析

亚洲中部干旱区"中亚天山北坡-新疆天山北坡-甘肃祁连山北坡"山前平原,在古丝绸之路和现代丝绸之路经济带时期均为社会、经济、文化最繁荣的重要地区。而一个地区某生物的生长发育除与降水、气温有关外,还与当地的水热匹配特征密切相关。中亚天山北坡区段水热不同步-新疆天山北坡区段水热较同步-甘肃祁连山北坡河西走廊区段水热同步的生态环境,深刻地影响着当地的天然动植物种类及其生长发育,使某些生物在研究区内各区段间形成了发生中心区、扩散区及无发生区的规律性分布;不同区段多项绿洲农业技术的差异性也反映出其对当地水热匹配特征的适应性。     

中国西北地区夏季降水的气候特征

利用西北地区119个气象站1961-2000年夏季降水资料,分析其空间分布特征和时间变化规律.选择典型多雨与少雨年,对美国NCEP/NCAR高空流、地气系统射出的长波辐射(OLR)场、赤道北太平洋海温(SST)与西北夏季降水的关系进行对比分析.结果表明:西北地区夏季降水具有明显的空间差异,最少的是新疆的吐鲁番气象站,为6.7 mm,最多的是陕西的佛坪气象站,为446.9 mm.多雨年北半球500 hPa极涡明显浅,西太平洋副热带高压强,700 hPa矢量风距平场中国西北地区为辐合区,700 hPa比湿距平中心位于中国西北地区,OLR主要负距平中心在西北地区,SST负距平主要在赤道太平洋东部.少雨年500 hPa极涡深,西太平洋副热带高压很弱,700 hPa矢量风距平场中国西北地区为辐散区,700 hPa比湿距正中心位于孟加拉湾西部,OLR主要正距平中心在西北地区;SST正距平主要在赤道太平洋东部.     

Long-term oscillation of drought conditions in the western China:an analysis of PDSI on a decadal scale

Water resource availability is one of the primary limiting factors with regard to ecosystems in the western China.Having a clear understanding of multi-scale drought patterns in this region is a key step for adaption and mitigation to climate change.The Palmer drought severity index(PDSI) is a widely applied index to assess drought conditions.In this study,long-term monthly self-calibrated PDSI data from 1951 to 2012 were examined for drought spatiotemporal variations in the western China.The results clearly indicated that apparent spatial heterogeneities were evidenced between two sub-regions(arid land with annual precipitation less than 200 mm and semiarid land with annual precipitation between 200 to 500 mm) as well as in the entire region of the western China.Ensemble empirical mode decomposition(EEMD) analyses on monthly PDSI and other atmospheric variable time-series obtained from the Department of Civil and Environmental Engineering,Princeton University revealed that all monthly time-series of variables could be completely decomposed into eight intrinsic mode functions(IMFs) and a trend(residual).This indicates that the monthly PDSI and atmospheric variables of the semiarid area in the western China contain eight quasi-period oscillations on various timescale spanning,seasonal to decadal cycles and a trend of a larger timescale from 1951–2012.The multi-scale drought patterns identified in this research could be powerful supports for decision-making regarding coping with droughts in this region.     

太行山前平原冬小麦生育期干旱分析——以保定市为例

对冬小麦生育期干旱进行精细分析,可以为农业生产和水资源管理提供参考信息,为降水、地下水动态以及作物耗水关系提供研究基础。采用有效降水和综合气象干旱指数(CI)方法,分析了太行山前平原冬小麦56个生育期及各生育阶段(苗期、越冬期、返青期、拔节～成熟期)的平均有效降水和气象干旱发生频率。研究发现冬小麦生育期平均有效降水为55.43 mm,分别占年有效降水和生育期降水量的13.6％和52.5％。其中,5月和10月是生育期有效降水的主要贡献月,平均有效降水量分别占到生育期有效降水量的35.7％、27.1％。生育期平均缺水350 mm以上,并且有效降水的月际、年际间差异明显。逐月旱涝级别和频率分布显示,生育期干旱平均发生频率为58.5％,逐月发生干旱的频率均在50％以上。12月易发生轻旱,2、3月易发生中旱,4月易发生重旱。总体上,太行山前平原冬小麦生育期及各生育阶段的有效降水都表现出非稳定性,逐月平均有效降水量均不同程度小于需水量,干旱发生频率冬后大于冬前。     

天山南北气候变化特征比较

根据新疆天山南北典型气象站1951～2008年气温、降水资料,运用回归分析和趋势分析,比较天山南北近58年的气候变化趋势和特征,结果表明：近58年来,天山北部气候总体呈暖湿趋势,年平均气温均升高,年降水量也不断增加;天山南部气候总体呈暖湿趋势,各站点气候因地而异,表现出不同的变化趋势和特征。总体来说,新疆气候趋于暖湿变...     

西北干旱区近50a旱涝时空变化及其防御措施研究

本文选取近50a西北干旱区21个代表站点降水量数据,采用Z指数法确定西北干旱区旱涝等级,分析近50a来西北干旱区旱涝时空变化。结果表明,从90年代起,旱涝灾害交替发生。干旱比多雨发生多,尤其在新疆的西部和南部旱灾发生频繁,但严重多雨比严重干旱更多发生。最后针对旱涝灾害提出防御措施。     

Agricultural irrigation requirements under future climate scenarios in China

 Projecting future water demand, especially in terms of agricultural irrigation demand, as well as identifying high-risk areas and establishing appropriate water demand management has become increasingly important in China. Climate scenarios provide opportunities to predict future irrigation requirements (IRs). We examined changes in IRs and agricultural drought in response to rising greenhouse gas concentrations in China using eight global climate models from the Intergovernmental Panel on Climate Change Fourth Assessment Report. In this research, Northeast China, the North China Plain and the Yarlung Tsangpo River Valley area in southeastern Tibet were estimated to receive more precipitation in the future, whereas Southeast and Northwest China, especially the Junggar and Tarim basins in Xinjiang Uygur autonomous region, will receive less precipitation. IRs will undergo a significant increase in summer (June–August), especially in July, whereas the smallest increase was predicted to occur in autumn (September–November). Middle rice was identified as the greatest contributor to the increase in total IRs. The areas predicted to experience significant increases in IRs include Northwest China (the Tarim and Junggar basins in Xinjiang Uygur autonomous region, the Hexi Corridor in Gansu province and the Guanzhong Plain in Shaanxi province), Southeast China (especially Fujian province), and Southwest China (Yarlung Tsangpo River Valley area in Tibet and the Sichuan Basin).     

基于CRU资料的中亚地区气候特征

基于中亚地区1971-2000年的CRU资料,利用一元线性回归法,分析中亚地区30 a的气候变化特征。结果表明：土库曼斯坦和乌兹别克斯坦的沙漠地区是中亚最为干旱的地区,也是气温最高的地区。塔吉克斯坦和吉尔吉斯斯坦冬季和春季降水多,夏季和秋季降水少,气温变化幅度相对较小。哈萨克斯坦的降水呈现西多东少,且主要集中在夏季,气温变化幅度较大,且西暖东冷。中亚地区气温年较差较小。新疆与中亚五国的气候有明显差异,新疆降水主要集中在夏季的天山山区,气温增暖明显,最高和最低气温与中亚西部的变化趋势相反。     

近50年来新疆天山南北坡典型流域冰川与冰川水资源的变化

冰川是大自然修筑的"固体水库",在水资源的构成中占有重要地位。新疆地处内陆干旱区,是我国现代冰川面积分布最广的地区之一。冰川和冰川融水为新疆灌溉农业发展提供了可靠的水资源保障。本文根据中国冰川编目及近年来其它冰川研究成果和监测资料,对1960年以来新疆,主要是天山山区的冰川与冰川径流的变化进行了分析。分析表明,受全球气候变暖的影响,上世纪60年代以来至本世纪初,天山冰川的变化整体上以退缩为主,1963-2000年冰川面积平均减少12.5%。但受地理位置和地势条件的影响,不同流域的冰川变化存在着较大的区域性差异。随着冰川的强烈退缩和冰川融水的增加,使得近十余年来新疆天山地区大部分冰川补给河流径流量呈增加的趋势。     

新疆天山北麓典型绿洲城市的水资源模糊综合评价研究

本文主要采用模糊评价法对新疆天山北麓的乌鲁木齐、石河子、克拉玛依三个绿洲城市的水资源利用程度进行评价分析,认为这三个城市的水资源开发利用虽处于开发利用的起步阶段,水资源开发规模较小,开发程度较低,利用率不高且对水资源的利用发展缓慢,制约了其水资源的可持续开发利用。最后提出解决新疆天山北麓城镇所面临的水资源问题的有效措施。     

近50a西北干旱区降水量变化差异分析

利用近50a西北干旱区21个代表站点的逐月降水量资料,通过逐月降水量趋势系数和对西北干旱区降水量变化贡献最大的月份的比较,深入分析近50a西北干旱区降水量变化的差异,从而得到以下结论:(1)降水量变化具有明显的季节差异。西北干旱区春季降水量变化较为复杂;夏季除了新疆西北部降水量减少趋势外,其他地区降水量都以增加为主;秋季形成了从南到北降水量依次增加的格局;冬季在新疆东部、南部和河西走廊的降水量有减少趋势,新疆西北部和柴达木盆地降水量以增加为主。(2)对夏半年降水量增加贡献最大的月份主要在7月,在新疆东部、南部和柴达木盆地。冬半年降水量增加贡献最大的月份主要在3月,在新疆西部、南部地区、河西走廊和柴达木盆地。     

Drought fluctuations based on dendrochronology since 1786 for the Lenglongling Mountains at the northwestern fringe of the East Asian summer monsoon region

The Lenglongling Mountains(LLM)located in northeastern part of the Tibet Plateau,belong to a marginal area of the East Asian summer monsoon(EASM)and are sensitive to monsoon dynamics.Two tree-ring width chronologies developed from six sites of Picea crassifolia in the LLM were employed to study the regional drought variability.Correlation and temporal correlation analyses showed that relationships between the two chronologies and self-calibrated Palmer Drought Severity Index(sc_PDSI)were significant and stable across time,demonstrating the strength of sc_PDSI in modeling drought conditions in this region.Based on the relationships,the mean sc_PDSI was reconstructed for the period from 1786 to 2013.Dry conditions prevailed during 1817–1819,1829–1831,1928–1931 and 1999–2001.Relatively wet periods were identified for 1792–1795 and 1954–1956.Spatial correlations with other fourteen precipitation/drought reconstructed series in previous studies revealed that in arid regions of Northwest China,long-term variability of moisture conditions was synchronous before the 1950 s at a decadal scale(1791–1954).In northwestern margin of the EASM,most of all selected reconstructions had better consistency in low-frequency variation,especially during dry periods,indicating similar regional moisture variations and analogous modes of climate forcing on tree growth in the region.