Spatio-temporal distribution and evolution trend of evapotranspiration in Xinjiang based on MOD16 data
ADILAIWufu, YUSUFUJIANGRusuli, REYILAIKadeer, JIANGHong Institute of Geographical Science and Tourism, Laboratory of Information Integration and Eco-Security,Xinjiang Normal University, Xinjiang Key Laboratory of Lake Environment and Resource in Arid Zone, Urumqi 830054, China 通讯作者:通讯作者:玉素甫江·如素力(1975- ),男,新疆喀什人,博士,教授,主要从事流域水文与生态系统、3S技术及其应用。E-mail: Yusupjan@xjnu.edu.cn 收稿日期:2017-01-4 修回日期:2017-05-6 网络出版日期:-- 版权声明:2017《地理研究》编辑部《地理研究》编辑部 基金资助:新疆研究生科研创新项目(XJGRI2016101)自治区青年科技创新人才培养工程项目(QN2015YX009)国家自然科学基金项目(41161007,41461006)新疆维吾尔自治区重点实验室专项资金资助项目(2014KL016) 作者简介: -->作者简介:阿迪来·乌甫(1992- ),女,新疆库车人,硕士,主要从事资源环境遥感。E-mail: Adilagupur@126.com
关键词:MOD16产品;地表 ET、PET;时空分布;变化趋势;新疆 Abstract Evapotranspiration (ET) plays an important role in the hydrological process as it is a major part in the ecological water balance. The surface ET can substantially influence on a regional scale the amount and spatial distribution of water resources. In arid lands like Xinjiang Uygur Autonomous Region located in Northwest China, ET is the main loss variable in water budget. It varies with land surface and local meteorological conditions. Quantitative estimation of spatio-temporal distribution and evolution of surface ET is essential for understanding the hydrological cycle and water resources management. Based on the measured data from MOD16 evapotranspiration product and meteorological stations, the spatio-temporal distribution and the evolution trend of land surface ET and potential evapotranspiration (PET) in Xinjiang during 2000-2014 were analyzed to further reveal the relationship between ET and PET. Results showed that: (1) the accuracy of the MOD16-ET (R2=0.83) in Xinjiang can meet the requirements, and can be used to examine the spatio-temporal distribution of surface ET; (2) the mean annual ET and PET were 364.29 mm and 1584.06 mm, respectively; the annual distribution was a unimodal pattern with an increase first then a decrease, the difference between ET and PET was the largest in summer, when there was a water shortage in the study area; (3) the mean ET and PET in northern Xinjiang are bigger than in southern Xinjiang, and that they are bigger in the west than in the east. The spatial distribution of PET was opposite to that of ET. The Altai Mountains, west shore of the Ili River Valley and western Tianshan Mountains had sufficient water supply, while the north and south of the Junggar Basin, the outer margin of eastern and western Xinjiang suffered from drought and water shortage; (4) during 2000-2014, ET was in a decreasing trend, and PET was in an increasing trend, which suggested that the drought was aggravated in Xinjiang in the past 15 years.
Keywords:MOD16;surface ET &;surface PET;spatio-temporal distribution;evolution trend;Xinjiang -->0 PDF (1329KB)元数据多维度评价相关文章收藏文章 本文引用格式导出EndNoteRisBibtex收藏本文--> 阿迪来·乌甫, 玉素甫江·如素力, 热伊莱·卡得尔, 姜红. 基于MODIS数据的新疆地表蒸散量时空分布及变化趋势分析[J]. 地理研究, 2017, 36(7): 1245-1256 https://doi.org/10.11821/dlyj201707005 ADILAIWufu, YUSUFUJIANGRusuli, REYILAIKadeer, JIANGHong. Spatio-temporal distribution and evolution trend of evapotranspiration in Xinjiang based on MOD16 data[J]. Geographical Research, 2017, 36(7): 1245-1256 https://doi.org/10.11821/dlyj201707005
新疆地处亚欧大陆中心、中国西北边陲,地处73°45′~96°39′E、34°34′~49°17′N,总面积约1.66万km2,是中国面积最大的省级行政区。北部为阿尔泰山脉,南部为昆仑山脉,天山山脉横亘中部,把新疆分隔为北疆和南疆两大区域,北疆的准葛尔盆地和南疆的塔里木盆地与此三座高山环抱构成了“三山夹二盆”的独特地域结构(图1)。 显示原图|下载原图ZIP|生成PPT 图1研究区土地利用/覆被和气象观测站分布图 -->Fig.1The spatial distribution of land use/cover and meteorological stations of the study area -->
为了验证MOD16蒸散产品在新疆地区地表ET时空反演的准确性,选取研究区内的21个代表性气象观测站(图1)的2000-2008年月时间序列的小型蒸发皿ET数据在“点”尺度上进行精度验证。蒸发皿ET是水分充足的条件下,蒸发皿所在区域自由水体的最大蒸发状况[40];在干旱半干旱区,实际ET主要是由水分和能量所决定,而蒸发皿ET不受水分的影响,决定其大小的主要因子是能量,因此蒸发皿ET与实际ET具有相反关系[41]。PET表示的是充分供水情况下的某一固定下垫面最大蒸散量[42,43]。可知蒸发皿ET与MOD16-PET相比蒸发皿ET与MOD16-ET更接近,可通过蒸发皿ET与MOD16-PET的相关性来检验MOD16蒸散产品在新疆地区的可行性。 结果表明(图2),蒸发皿实测ET与MOD16-PET之间具有较高的相关性,相关系数达到R2=0.83,MOD16蒸散产品在该地区验证精度良好。MOD16蒸散产品中的PET精度验证满足要求,说明MOD16产品在新疆地区具有适用性,可以用于该研究区地表ET的时空分布特征研究。图2显示,蒸发皿实测ET与MOD16-PET数据构成的散点图的趋势线往蒸发皿实测ET(x轴)一边倾斜,说明实测ET比MOD16-PET偏大。主要的原因在于蒸发皿中水体的反射率和不同下垫面的反射率是不同的,再加上白天存储在蒸发皿的热量,使蒸发皿在夜间也有蒸发过程,而PET仅仅发生在白天,夜间没有PET。因此,蒸发皿实测ET与PET之间必然有差异,即蒸发皿实测ET大于MOD16-PET。 显示原图|下载原图ZIP|生成PPT 图2气象站月实测ET和MOD16-PET的关系 -->Fig.2Relationship between MOD16 PET product and monthly ET at meteorological stations -->
3.2 平均ET、PET的时间分布特征
2000-2014年期间新疆地表ET、PET年际波动不大,ET波动范围为335.86~385 mm之间,多年平均ET为364.29 mm;PET波动范围为1516.84~1655.97 mm,多年平均PET为1584.06 mm。年ET波动最为突出的年份是2005年和2009年,相对变化率分别为5.38%和-8.46%。年PET波动最为突出的年份是2007年和2003年,相对变化率分别为4.34%和-4.43%(图3a)。ET为地表实际蒸散量,PET为一定气象条件下水分供应不受限制时的最大蒸发蒸腾量,ET与PET的差距可以说明地表的缺水情况,也就是干旱程度。从图3可以看出,新疆地表ET与PET有较大的差距,说明新疆整体上缺水、干旱。 新疆地表ET、PET的年内分布处于先增大后减少的单峰型变化趋势,峰值位于7月(图3b)。月平均ET约23.96 mm,PET约78.48 mm,ET、PET都比较集中在5-9月,5-7月处于快速增长趋势,7月达到最高值,分别为89.95 mm和217.35 mm,8月开始迅速下降,1月处于最小值,分别为22.10 mm和61.39 mm,从10月到次年2月的ET、PET波动比较平缓。8月ET与PET之间的差距最大,说明新疆在8月处于最干旱状态。按季节来看,春季(3-5月)ET与PET处于增加趋势,3月开始气温慢慢升高、降水量逐渐增多、植被返青,因此ET、PET也随之升高;夏季(6-8月)气温达到最高值、受西风气流的影响,水汽来源充沛,使得降雨量大、太阳辐射强烈、不同地貌类型的ET、PET达到最大值,因此在夏季ET、PET比其他季节最大;秋季(9-11月)气温逐渐下降,雨量减少、植被开始枯竭,ET、PET随之急剧减少;冬天(12月-次年2月)气温低、降水量少、太阳辐射较弱,ET、PET保持最低值,无明显的变化。夏季ET、PET之间的差距最大,说明此时新疆最干旱、最缺水。 显示原图|下载原图ZIP|生成PPT 图32000-2014 年新疆ET、PET不同年月变化 -->Fig.3Annual and monthly variations of ET and PET in Xinjiang during 2000-2014 -->
3.3 平均ET、PET的空间分布特征
根据ET的分布情况,将新疆分为北疆、南疆、天山等三个区域进行ET、PET的空间分布分析。如图4a所示,2000-2014年新疆地表ET、PET的空间分布存在明显的差异,两者整体上呈现出北疆大于南疆、西部大于东部的分布特征,且两者的空间分布状况正好相反。多年平均ET波动范围为48~786.6 mm,PET波动范围为626.0~2630.9 mm。北疆阿尔泰山一带、伊犁河谷以及天山西段植被覆盖区ET值比其他区域显著高,在248~786.6 mm之间,PET值比较低,在626.0~1454.5 mm之间。北疆的准噶尔盆地南部和北部、哈密以及南疆塔里木盆地外缘 ET值均比较低,在48~248 mm之间,PET值较高,在1454.5~2630.9 mm之间。由于MOD16产品覆盖范围为有植被区域,所以在图中南疆的塔克拉玛干沙漠腹地和喀喇昆仑山山脉带状山麓地带、东部大范围荒漠戈壁区等没有植被区域为空白,没有数据。 显示原图|下载原图ZIP|生成PPT 图4新疆年平均与季节平均ET、PET空间分布 -->Fig.4The spatial distribution of annual and seasonal ET and PET in Xinjiang -->
图5a表示近15年来新疆地表ET、PET变化趋势空间分布情况。从图5a中可以看出,ET在准噶尔盆地南部、塔城和博州部分地区有明显增加趋势,面积约占总面积的10%;准噶尔盆地北部和南疆塔里木盆地外缘水资源较丰富的绿洲区域轻微增加或者基本不变趋势,面积分别占29%和42%;阿尔泰山脉一带、伊犁河谷及其西边的天山中段有减少趋势,轻微减少和严重减少区域面积约占总面积的16%和3%。PET在天山中段的伊犁草原、巴音布勒克草原以及哈密巴里坤草原等区域有明显增加趋势,面积约占总面积的4%;准噶尔盆地北部、博州、伊犁西部等区域有轻微增加或者基本不变趋势,约占总面积的17%和26%;在南疆环塔里木盆地的库尔勒市—阿克苏市—喀什市—和田市沿线绿洲和昆仑山北坡山前荒漠草原等区域主要有轻微减少趋势,约占总面积的32%。新疆多年ET总体上处于基本不变趋势,基本不变的区域面积约占总面积的42%;PET处于轻微增加趋势,约占总面积的32%。按增加或减少的趋势所占的面积来看,ET处于增加趋势的区域面积小于减少趋势的区域面积,PET处于增加趋势的区域面积明显大于减少趋势的区域面积。 显示原图|下载原图ZIP|生成PPT 图5新疆年际与不同季节ET、PET变化趋势 -->Fig.5The change trend of annual and seasonal ET and PET in Xinjiang during 2000-2014 -->
新疆已有的蒸散量的研究主要基于长期的气象观测资料,针对PET时空变化特征及原因进行分析。董煜等[46]基于Penman-Monteith公式和气象资料分析新疆PET时空变化特征及变化原因,并对未来PET变化趋势进行了预测。张山清等[34]利用逐月实测气象资料与Penman-Monteith公式,通过Mann-kendall检测和空间插值技术,分析了新疆1961-2008年PET时空变化特征。而本文在利用高分辨率遥感产品和连续时间段的气象观测数据,分析ET、PET时空分布特征的基础上,深入讨论两者的关系和多年变化趋势,从而反映区域干旱时空分布状况。由此得到的研究成果,能够弥补已有研究的不足,并指出以后的结合遥感技术和地面观测资料,由简单到复杂的发展方向。由于区域地表ET、PET的变化过程十分复杂,受制于多种气象要素和地理环境的综合影响,而且这些要素对不同区域的影响机理不尽相同。因此,在本文的基础上,结合研究区地表和实际情况,进一步深入探讨不同要素对ET、PET的贡献将是下一步的研究重点。 The authors have declared that no competing interests exist.
[YangDong, GuoPanpan, YiFengjia, et al.The spatio-temporal characteristics of evaporation change and its influence in Gannan Prefecture in recent 35 years. , 2011, 25(6): 147-153.]URL [本文引用: 1]
[PangZhonghe.Mechanism of water cycle changes and implications on water resources regulation in Xinjiang Uygur Autonomous Region. , 2014, 34(5): 907-917.] [本文引用: 1]
[ZhouYanzhao, ZhouJian, LiYan, et al.Simulating the evapotranspiration with SEBAL and Modified SEBAL (M-SEBAL) models over the desert and oasis of the middle reaches of the Heihe River. , 2014, 36(6): 1526-1537.] [本文引用: 1]
[ZhangChangchun, WeiJiahua, WangGuangqian, et al.Survey and headway of study on remote sensing regional evaporation. , 2004, 18(2): 174-177.] [本文引用: 1]
[ZhangRenhua,SunXiaomin,LiuJiyuan,et al.Determination of regional distribution of crop transpiration and soil water use efficiency using quantitative remote sensing data through inversion. , 2001, 31(11): 959-968.] [本文引用: 1]
[GaoYanchun, LongDi.Progress in models for evapotranspiration estimation using remotely sensed data. , 2008, 12(3): 515-528.] [本文引用: 1]
[12]
Moran MS, Rahman AF, Washburne JC, et al.Combining the Penman-Monteith equation with measurements of surface temperature and reflectance to estimate evaporation rates of semiarid grassland. , 1996, 80(2-4): 87-109. [本文引用: 1]
[13]
JiangL, IslamS.A methodology for estimation of surface evapotranspiration over large areas using remote sensing observations. , 1999, 26(17): 2773-2776. [本文引用: 1]
[14]
BastiaanssenW, PelgrumH, WangJ, et al.A remote sensing surface energy balance algorithm for land . , 1998, 212-213(1-4): 198-212. [本文引用: 1]
[15]
SuZ, SchmuggeT, Kustas WP, et al.Two models for estimation of the roughness height for heat transfer between the land surface and the atmosphere. , 2001, 40(11): 1933-1951. [本文引用: 1]
[16]
Kustas WP, Norman JM.Evaluation of soil and vegetation heat flux predictions using a simple two-source model with radiometric temperatures for partial canopy cover. , 1999, 94(1): 13-29. [本文引用: 1]
[LiuYuan, WangYing, YangXiaoguang.Trends in reference crop evapotranspiration and possible climatic factors in the North China Plain. , 2010, 30(4): 923-932.] [本文引用: 1]
[LiBaofu, ChenYaning, LiWeihong, et al.Remote sensing and the SEBAL model for estimating evapotranspiration in the Tarim River. , 2011, 66(9): 1230-1238.] [本文引用: 1]
[WuXuejiao, ZhouJian, LiYan, et al.Estimating the evapotranspiration in the middle reaches of the Heihe River by SEBS model based on the eddy covariance system. , 2014, 36(6): 1538-1547.] [本文引用: 1]
[20]
Mu QZ, Zhao MS, Running SW.Improvements to a MODIS global terrestrial evapotranspiration algorithm. , 2011, 115(8): 1781-1800. [本文引用: 1]
[21]
Mu QZ, Heinsch FA, ZhaoM,et al.Development of a global evapotranspiration algorithm based on MODIS and global meteorology data. , 2007, 111(4): 519-536. [本文引用: 1]
[WuGuiping, LiuYuanbo, ZhaoXiaosong, et al.Spatio-temporal variations of evapotranspiration in Poyang Lake Basin using MOD16 products. , 2013, 32(4): 617-627.] [本文引用: 1]
[FanJianzhong, LiDengke, GaoMaosheng.Spatio-temporal variations of evapotranspiration in Shaanxi province using MOD16 product . , 2014, 23(9): 1536-1543.] [本文引用: 1]
[WeiHejie, ZhangYanfang, ZhuNi, et al.Spatial and temporal characteristic of ET in the Weihe River Basin based on MOD16 data. , 2015, 35(2): 414-422.] [本文引用: 1]
[YangXiuqin, WangLei, WangKai.Spatio-temporal distribution of terrestrial evapotranspiration in Huaihe River Basin based on MOD16 ET data. , 2015, 37(5): 1343-1352.] [本文引用: 1]
[HeTian, ShaoQuanqin.Spatial-temporal variation of terrestrial evapotranspiration in China from 2001 to 2010 using MOD16 products. Journal of , 2014, 16(6): 979-988.] [本文引用: 1]
[ChengWeiming, ChaiHuixia, ZhouChenghu, et al.The spatial distribution patterns of digital geomorphology in Xinjiang. , 2009, 28(5): 1157-1169.] [本文引用: 1]
[28]
ChenY, TakeuchiK, XuC, et al.Regional climate change and its effects on river runoff in the Tarim Basin, China. , 2006, 20(10): 2207-2216. [本文引用: 1]
[29]
ChenY, XuC, HaoX, et al.Fifty-year climate change and its effect on annual runoff in the Tarim River Basin, China. , 2009, 208(1-2): 53-61. [本文引用: 1]
[CiHui, ZhangQiang, ZhangJianghui, et al.Spatio-temporal variations of extreme precipitation events within Xinjiang during 1961-2010. , 2014, 33(10): 1881-1891.] [本文引用: 1]
[DongYu, HaimitiYimiti.Spatio-temporal variability and trend of potential evapotranspiration in Xinjiang from 1961 to 2013. , 2015, 31(1): 153-161.] [本文引用: 1]
[ShiXin, WuPute, WangYubao, et al.Analysis of temporal-spatial characteristics of reference evapotranspiration in Xinjiang province during 1960-2009. , 2012, 32(1): 10-14.] [本文引用: 1]
[HuShunjun, TianChangyan, SongYudong, et al.Conversion coefficient of water surface evaporation in Tarim River Basin. , 2005, 25(5): 649-651.] [本文引用: 1]
[DuanChunfeng, MiaoQilong, CaoWen, et al.Estimation of reference crop evapotranspiration by Chinese pan evaporation in Northwest China. , 2012, 28(4): 94-99.] [本文引用: 1]
[YangXiuqin, WangGuojie, YeJinyin, et al.Spatial and temporal changing analysis of terrestrial evapotranspiration in Huai River Basin based on GLEAM data. , 2015, 31(9): 133-139.] [本文引用: 1]
[WeiFengying. Beijing: China Meteorological Press, 1999.] [本文引用: 1]
[40]
Allan RG, Pereira LS, RaesD, et al.Crop evapotranspiration-Guidelines for computing crop water requirements-FAO Irrigation and Drainage Paper 56. , 1998, 56. [本文引用: 1]
[LiuBo, XiaoZiniu, MaZhuguo, et al.Relationship between pan evaporation and actual evaporation in different humid and arid regions of China. , 2010, 29(3): 629-636.] [本文引用: 1]
[42]
Cheng YF, Wang GX, Xi HY, et al.Variations of land evapotranspiration in the plain of the middle reaches of Heihe River in the recent 35 years. , 2007, 29(3): 406-412. [本文引用: 1]
[43]
Yin YH, Wu SH, ZhengD, et al.The regional differences of dry-wet change in China in recent 30 years. , 2005, 50(15): 1636-1642. [本文引用: 1]
[44]
Roderick ML, Farquhar GD.The cause of decreased pan evaporation over the past 50 years. , 2002, 298(5597): 1410-1411. [本文引用: 1]
[DongYu,ChenXuegang, HuJiangling.Spatio-temporal variability of potential evapotranspiration in Xinjiang and estimation of future trend. , 2015, (9): 90-94.] [本文引用: 1]