气象因子对青藏高原高寒草甸参考蒸散的驱动特征
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摘要
青藏高原被誉为"中华水塔",在全球气候变化的大背景下,青藏高原的水热平衡发生了一系列变化,研究青藏高原蒸散与气候变化关系,对于揭示气候变化对高原水文过程影响具有重要意义。基于2011-2016年6年自动观测连续数据,选取净辐射总量、气温、饱和水汽压差、降水、风速、相对湿度、日照时数7个主要气象因子,采用随机森林分析方法,分析了参考蒸散的季节及年际变化趋势,评估各气象因子对青藏高原参考蒸散的贡献。结果表明:1)在季节尺度上,参考蒸散总体表现为单峰曲线,即1-7月呈增加趋势,7月份达到最大值(132.48mm),7-12月开始逐渐下降;在年际尺度上,参考蒸散总体呈现递增的趋势,平均为1 023.03mm,且每年以29.61mm增加趋势上升。2)净辐射是影响参考蒸散年内变异最重要的气象因子,其他气象因子对其影响强弱排序为饱和水汽压差>最高气温>日照时数>平均气温;对于生长季参考蒸散,气象因子对其影响强弱依次排序为净辐射>日照时数>饱和水汽压差>最高气温。而降水、风速、最低气温和平均气温对年内参考蒸散和生长季参考蒸散影响较小。对非生长季参考蒸散,其所受气象因子强弱排序为净辐射>饱和水汽压差>风速>最高气温>平均气温,而相对湿度、日照时数、降水和最低气温对非生长季参考蒸散贡献较小。本研究表明,青藏高原矮嵩草(Kobresia humilis)草甸参考蒸散主要受净辐射驱动,且相比于平均温和最低气温,最高气温对其参考蒸散影响更大,这对于明晰高寒草甸水循环过程具有重要意义。
The Qinghai-Tibet Plateau,also known as"China's water tower",has undergone a series of changes in the water-heat balance in its alpine meadows,which are attributed to global climate change.Therefore,it is vital to examine the effects of climate change on the hydrological processes on the plateau by analyzing the relationship between evapotranspiration and meteorological factors.In the present study,based on automatically observed meteorological data from 2011-2016,random forest analysis was applied to quantitatively evaluate the relative importance of seven major meteorological factors(e.g.,net radiation,temperature,apor pressure deficit,rainfall,wind speed,relative humidity,and sunshine hours)on the reference evapotranspiration(ET0)to explore the key meteorological factors affecting variation in ET0.In addition,the seasonal and interannual variation in ET0 from 2011-2016 were also analyzed.The results show that 1)at the seasonal scale,ET0 could be characterized by a unimodal relationship that increases from January to July,with the maximum value occurring in July(132.48 mm),then decreases from July to December.At the interannual scale,the ET0 increased significantly from 2011-2016 with an average of 1 023.03 m2)The net radiation was the most important factor affecting the annual variation in ET0,followed by vapor pressure deficit,maximum air temperature,sunshine hours,and mean air temperature.The impact of meteorological factors on the growing season ET0 was ranked in the following order:net radiation > sunshine hours> vapor pressure deficit> maximum air temperature;rainfall,wind speed,minimum air temperature,and mean air temperature had little impact.The impact of meteorological factors on the non-growing season ET0 was ranked in the following order:net radiation > vapor pressure deficit> wind speed > maximum air temperature> mean air temperature;relative humidity,sunshine hours,rainfall,and the minimum air temperature had little impact.Our results indicated that the ET0 of an alpine Kobresia meadowin the northern Qinghai-Tibet Plateau was dominated by net radiation.Moreover,the maximum air temperature had stronger effects on the ET0 than did mean air temperature or minimum air temperature,which could provide a new insight for the appropriate management of plateau water resources.
The Qinghai-Tibet Plateau,also known as"China's water tower",has undergone a series of changes in the water-heat balance in its alpine meadows,which are attributed to global climate change.Therefore,it is vital to examine the effects of climate change on the hydrological processes on the plateau by analyzing the relationship between evapotranspiration and meteorological factors.In the present study,based on automatically observed meteorological data from 2011-2016,random forest analysis was applied to quantitatively evaluate the relative importance of seven major meteorological factors(e.g.,net radiation,temperature,apor pressure deficit,rainfall,wind speed,relative humidity,and sunshine hours)on the reference evapotranspiration(ET0)to explore the key meteorological factors affecting variation in ET0.In addition,the seasonal and interannual variation in ET0 from 2011-2016 were also analyzed.The results show that 1)at the seasonal scale,ET0 could be characterized by a unimodal relationship that increases from January to July,with the maximum value occurring in July(132.48 mm),then decreases from July to December.At the interannual scale,the ET0 increased significantly from 2011-2016 with an average of 1 023.03 m2)The net radiation was the most important factor affecting the annual variation in ET0,followed by vapor pressure deficit,maximum air temperature,sunshine hours,and mean air temperature.The impact of meteorological factors on the growing season ET0 was ranked in the following order:net radiation > sunshine hours> vapor pressure deficit> maximum air temperature;rainfall,wind speed,minimum air temperature,and mean air temperature had little impact.The impact of meteorological factors on the non-growing season ET0 was ranked in the following order:net radiation > vapor pressure deficit> wind speed > maximum air temperature> mean air temperature;relative humidity,sunshine hours,rainfall,and the minimum air temperature had little impact.Our results indicated that the ET0 of an alpine Kobresia meadowin the northern Qinghai-Tibet Plateau was dominated by net radiation.Moreover,the maximum air temperature had stronger effects on the ET0 than did mean air temperature or minimum air temperature,which could provide a new insight for the appropriate management of plateau water resources.
引文
[1]张建财,张丽,郑艺,田向军,周宇.基于LPJ模型的中亚地区植被净初级生产力与蒸散模拟.草业科学,2015,32(11):1721-1729.ZHANG J C,ZHANG L,ZHENG Y,TIAN X J,ZHOU Y.Simulation of vegetation net primary productivity and evapotranspiration based on LPJ model in Central Asia.Pratacultural Science,2015,32(11):1721-1729.
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[3]QIU X F,LIU C M,ZENG Y.Changes of pan evaporation in the recent 40years over the Yellow River Basin.Journal of Natural Resources,2003,18(4):437-442.
[4]RODERICK M L,HOBBINS M T,FARQUHAR G D.Panevaporation trends and the terrestrial water balance.Ⅱ.energybalance and interpretation.Geography Compass,2009,3(2):761-780.
[5]ESPADAFOR M,LORITE I J,GAVILN P,BERENGENA J.An analysis of the tendency of reference evapotranspiration estimates and other climate variables during the last 45years in Southern Spain.Agricultural Water Management,2011,98(6):1045-1061.
[6]RAZYASEEF N,YAKIR D,SCHILLER G,COHEN S.Dynamics of evapotranspiration partitioning in a semi-arid forest as affected by temporal rainfall patterns.Agricultural&Forest Meteorology,2012,157(2):77-85.
[7]SERRAT-CAPDEVILA A,SCOTT R L,SHUTTLEWORTH W J,VALDS J B.Estimating evapotranspiration under warmer climates:Insights from a semi-arid riparian system.Journal of Hydrology,2011,399(1):1-11.
[8]LIU X,ZHENG H,ZHANG M,LIU C.Identification of dominant climate factor for pan evaporation trend in the Tibetan Plateau.Journal of Geographical Sciences,2011,21(4):594-608.
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[10]李斌,李丽娟,覃驭楚,李九一,柳玉梅,曾宏伟.澜沧江流域潜在蒸散发敏感性分析.资源科学,2011,33(7):1256-1263.LI B,LI L J,QIN Y C,LI J Y,LIU Y M,ZENG H W.Sensitivity analysis of potential evapotranspiration in the Lancang River Basin.Resources Science,2011,33(7):1256-1263.
[11]刘小莽,郑红星,刘昌明,曹英杰.海河流域潜在蒸散发的气候敏感性分析.资源科学,2009,31(9):1470-1476.LIU X M,ZHENG H X,LIU C M,CAO Y J.Sensitivity of the potential evapotranspiration to key climatic variables in the Haihe River Basin.Resources Science,2009,31(9):1470-1476.
[12]SOLOMON S,QIN D,MANNING M,MARQUIS M,AVERYT K,TIGNOR M,MILLER H,CHEN Z.The physical science basis.Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC).Computational Geometry,2013,18(2):95-123.
[13]MCAFEE S A.Methodological differences in projected potential evapotranspiration.Climatic Change,2013,120(4):915-930.
[14]WANG X H,GUO M H,XU X Y,WEN J.Changingtrends of reference crop evapotranspiration and impact factors in Yunnan Mengzhi Plain in recent 50years.Procedia Earth&Planetary Science,2012,5(32):326-334.
[15]王顺久.青藏高原积雪变化及其对中国水资源系统影响研究进展.高原气象,2017,36(5):1153-1164.WANG S J.Progresses in variability of snow cover over the Qinghai-Tibetan Plateau and its impact on water resources in China.Plateau Meteorology,2017,36(5):1153-1164.
[16]段春锋,缪启龙,曹雯.塔克拉玛干沙漠周边地区潜在蒸散时空演变特征及其主要影响因素.中国沙漠,2012,32(6):1723-1730.DUAN C F,MIAO Q L,CAO W.Spatio-temporal variations ofpotential evapotranspiration around Taklimakan desert and the main influencing factors.Journal of Desert Research,2012,32(6):1723-1730.
[17]ZHANG C G,SHEN Y J,LIU F G,MENG L.Changes in reference evapotranspiration over an agricultural region in the Qinghai-Tibetan plateau,China.Theoretical&Applied Climatology,2014,123(1/2):1-9.
[18]WANG Y,JIANG T,BOTHE O,FRAEDRICH K.Changes of pan evaporation and reference evapotranspiration in the Yangtze River basin.Theoretical&Applied Climatology,2007,90(1/2):13-23.
[19]郭小伟,杜岩功,林丽,李以康,张法伟,李茜,刘淑丽,欧阳经政,曹广民.青藏高原北缘3种高寒草地的CH4、CO2和N2O通量特征的初步研究.草业科学,2016,33(1):27-37.GUO X W,DU Y G,LI L,LI Y K,ZHANG F W,LI Q,LIU S L,OUYANG J Z,CAO G M.CH4,CO2and N2O flux among three types of alpine meadow in the north regions of Qinghai-Tibetan Plateau.Pratacultural Science,2016,33(1):27-37.
[20]罗久富,周金星,赵文霞,董林水,郑景明.围栏措施对青藏高原高寒草甸群落结构和稳定性的影响.草业科学,2017,34(3):565-574.LUO J F,ZHOU J X,ZHAO W X,DONG L S,ZHENG J M.Effect of fences on functional groups and stability of the alpine meadow plant community in the Qinghai-Tibet Plateau.Pratacultural Science,2017,34(3):565-574.
[21]BREIMAN L.Randomforests.Machine Learning,2001,45(1):5-32.
[22]李念,孙维君,秦翔,杜文涛,陈记祖,郑昭佩.2010-2014年祁连山老虎沟流域高寒草甸蒸散发变化特征.中国科技论文,2017,12(9):1015-1023.LI N,SUN W J,QIN X,DU W T,CHEN J Z,ZHENG Z P.Characteristics of evapotranspiration in an alpine meadow in the Laohugou catchment in Qilian Mountains from 2010to 2014.China Science Paper,2017,12(9):1015-1023.
[23]王利辉,何晓波,丁永建.青藏高原中部高寒草甸蒸散发特征及其影响因素.冰川冻土,2018,39(6):1-6.WANG L H,HE X B,DING Y J.Characteristics and influence factors of the evaportranspiration from a alpine meadow in central Qinghai Tibet Plateau.Journal of Glaciology and Geocryology,2018,39(6):1-6.
[24]张娜,金建新,佟长福,张红玲,屈忠义.西藏参考作物蒸散量时空变化特征与影响因素.干旱区研究,2017,34(5):1027-1034.ZHANG N,JIN J X,TONG C F,ZHANG H L,QU Z Y.Spatio temporal variation of evapotranspiration of referred crops and the affecting factors in Tibet.Arid Zone Research,2017,34(5):1027-1034.
[25]白虎志,董文杰,马振锋.青藏高原及邻近地区的气候特征.高原气象,2004,23(6):890-897.BAI H Z,DONG W J,MA Z F.Climatic characteristics of Qinghai-Xizang Plateau and its surrounding.Plateau Meteorology,2004,23(6):890-897.
[26]李生辰,徐亮,郭英香,钱维宏,张国庆,李川.近34年青藏高原年气温变化.中国沙漠,2006,26(1):27-34.LI S C,XU L,GUO Y X,QIAN W H,ZHANG G Q,LI C.Change of annual air temperature over Qinghai-Tibet Plateau during recent 34years.Journal of Desert Research,2006,26(1):27-34.
[27]刘晓英,李玉中,钟秀丽,曹金峰,袁小环.基于称重式蒸渗仪实测日值评价16种参考作物蒸散量(ET0)模型.中国农业气象,2017,38(5):278-291.LIU X Y,LI Y Z,ZHONG X L,CAO J F,YUAN X H.Evaluation of 16models for reference crop evapotranspiration(ET0)based on daily values of weighing lysimeter measurements.Chinese Journal of Agrometeorology,2017,38(5):278-291.
[28]HUPET F,VANCLOOSTER M.Effect of the sampling frequency of meteorological variables on the estimation of the reference evapotranspiration.Journal of Hydrology,2001,243(3):192-204.
[2]ALLAN R G,PEREIRA L S,RAES D,SMITH M.Crop evapotranspiration:Guidelines for computing crop water requirements.Rome:FAO Irrigation&Drainage Paper,1998:56.
[3]QIU X F,LIU C M,ZENG Y.Changes of pan evaporation in the recent 40years over the Yellow River Basin.Journal of Natural Resources,2003,18(4):437-442.
[4]RODERICK M L,HOBBINS M T,FARQUHAR G D.Panevaporation trends and the terrestrial water balance.Ⅱ.energybalance and interpretation.Geography Compass,2009,3(2):761-780.
[5]ESPADAFOR M,LORITE I J,GAVILN P,BERENGENA J.An analysis of the tendency of reference evapotranspiration estimates and other climate variables during the last 45years in Southern Spain.Agricultural Water Management,2011,98(6):1045-1061.
[6]RAZYASEEF N,YAKIR D,SCHILLER G,COHEN S.Dynamics of evapotranspiration partitioning in a semi-arid forest as affected by temporal rainfall patterns.Agricultural&Forest Meteorology,2012,157(2):77-85.
[7]SERRAT-CAPDEVILA A,SCOTT R L,SHUTTLEWORTH W J,VALDS J B.Estimating evapotranspiration under warmer climates:Insights from a semi-arid riparian system.Journal of Hydrology,2011,399(1):1-11.
[8]LIU X,ZHENG H,ZHANG M,LIU C.Identification of dominant climate factor for pan evaporation trend in the Tibetan Plateau.Journal of Geographical Sciences,2011,21(4):594-608.
[9]曹雯,申双和,段春锋.西北地区生长季参考作物蒸散变化成因的定量分析.地理学报,2011,66(3):407-415.CAO W,SHEN S H,DUAN C F.Quantification of the causes for reference crop eapotranspirationchanges in growing season in northwest China.Acta Ecologica Sinica,2011,66(3):407-415.
[10]李斌,李丽娟,覃驭楚,李九一,柳玉梅,曾宏伟.澜沧江流域潜在蒸散发敏感性分析.资源科学,2011,33(7):1256-1263.LI B,LI L J,QIN Y C,LI J Y,LIU Y M,ZENG H W.Sensitivity analysis of potential evapotranspiration in the Lancang River Basin.Resources Science,2011,33(7):1256-1263.
[11]刘小莽,郑红星,刘昌明,曹英杰.海河流域潜在蒸散发的气候敏感性分析.资源科学,2009,31(9):1470-1476.LIU X M,ZHENG H X,LIU C M,CAO Y J.Sensitivity of the potential evapotranspiration to key climatic variables in the Haihe River Basin.Resources Science,2009,31(9):1470-1476.
[12]SOLOMON S,QIN D,MANNING M,MARQUIS M,AVERYT K,TIGNOR M,MILLER H,CHEN Z.The physical science basis.Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC).Computational Geometry,2013,18(2):95-123.
[13]MCAFEE S A.Methodological differences in projected potential evapotranspiration.Climatic Change,2013,120(4):915-930.
[14]WANG X H,GUO M H,XU X Y,WEN J.Changingtrends of reference crop evapotranspiration and impact factors in Yunnan Mengzhi Plain in recent 50years.Procedia Earth&Planetary Science,2012,5(32):326-334.
[15]王顺久.青藏高原积雪变化及其对中国水资源系统影响研究进展.高原气象,2017,36(5):1153-1164.WANG S J.Progresses in variability of snow cover over the Qinghai-Tibetan Plateau and its impact on water resources in China.Plateau Meteorology,2017,36(5):1153-1164.
[16]段春锋,缪启龙,曹雯.塔克拉玛干沙漠周边地区潜在蒸散时空演变特征及其主要影响因素.中国沙漠,2012,32(6):1723-1730.DUAN C F,MIAO Q L,CAO W.Spatio-temporal variations ofpotential evapotranspiration around Taklimakan desert and the main influencing factors.Journal of Desert Research,2012,32(6):1723-1730.
[17]ZHANG C G,SHEN Y J,LIU F G,MENG L.Changes in reference evapotranspiration over an agricultural region in the Qinghai-Tibetan plateau,China.Theoretical&Applied Climatology,2014,123(1/2):1-9.
[18]WANG Y,JIANG T,BOTHE O,FRAEDRICH K.Changes of pan evaporation and reference evapotranspiration in the Yangtze River basin.Theoretical&Applied Climatology,2007,90(1/2):13-23.
[19]郭小伟,杜岩功,林丽,李以康,张法伟,李茜,刘淑丽,欧阳经政,曹广民.青藏高原北缘3种高寒草地的CH4、CO2和N2O通量特征的初步研究.草业科学,2016,33(1):27-37.GUO X W,DU Y G,LI L,LI Y K,ZHANG F W,LI Q,LIU S L,OUYANG J Z,CAO G M.CH4,CO2and N2O flux among three types of alpine meadow in the north regions of Qinghai-Tibetan Plateau.Pratacultural Science,2016,33(1):27-37.
[20]罗久富,周金星,赵文霞,董林水,郑景明.围栏措施对青藏高原高寒草甸群落结构和稳定性的影响.草业科学,2017,34(3):565-574.LUO J F,ZHOU J X,ZHAO W X,DONG L S,ZHENG J M.Effect of fences on functional groups and stability of the alpine meadow plant community in the Qinghai-Tibet Plateau.Pratacultural Science,2017,34(3):565-574.
[21]BREIMAN L.Randomforests.Machine Learning,2001,45(1):5-32.
[22]李念,孙维君,秦翔,杜文涛,陈记祖,郑昭佩.2010-2014年祁连山老虎沟流域高寒草甸蒸散发变化特征.中国科技论文,2017,12(9):1015-1023.LI N,SUN W J,QIN X,DU W T,CHEN J Z,ZHENG Z P.Characteristics of evapotranspiration in an alpine meadow in the Laohugou catchment in Qilian Mountains from 2010to 2014.China Science Paper,2017,12(9):1015-1023.
[23]王利辉,何晓波,丁永建.青藏高原中部高寒草甸蒸散发特征及其影响因素.冰川冻土,2018,39(6):1-6.WANG L H,HE X B,DING Y J.Characteristics and influence factors of the evaportranspiration from a alpine meadow in central Qinghai Tibet Plateau.Journal of Glaciology and Geocryology,2018,39(6):1-6.
[24]张娜,金建新,佟长福,张红玲,屈忠义.西藏参考作物蒸散量时空变化特征与影响因素.干旱区研究,2017,34(5):1027-1034.ZHANG N,JIN J X,TONG C F,ZHANG H L,QU Z Y.Spatio temporal variation of evapotranspiration of referred crops and the affecting factors in Tibet.Arid Zone Research,2017,34(5):1027-1034.
[25]白虎志,董文杰,马振锋.青藏高原及邻近地区的气候特征.高原气象,2004,23(6):890-897.BAI H Z,DONG W J,MA Z F.Climatic characteristics of Qinghai-Xizang Plateau and its surrounding.Plateau Meteorology,2004,23(6):890-897.
[26]李生辰,徐亮,郭英香,钱维宏,张国庆,李川.近34年青藏高原年气温变化.中国沙漠,2006,26(1):27-34.LI S C,XU L,GUO Y X,QIAN W H,ZHANG G Q,LI C.Change of annual air temperature over Qinghai-Tibet Plateau during recent 34years.Journal of Desert Research,2006,26(1):27-34.
[27]刘晓英,李玉中,钟秀丽,曹金峰,袁小环.基于称重式蒸渗仪实测日值评价16种参考作物蒸散量(ET0)模型.中国农业气象,2017,38(5):278-291.LIU X Y,LI Y Z,ZHONG X L,CAO J F,YUAN X H.Evaluation of 16models for reference crop evapotranspiration(ET0)based on daily values of weighing lysimeter measurements.Chinese Journal of Agrometeorology,2017,38(5):278-291.
[28]HUPET F,VANCLOOSTER M.Effect of the sampling frequency of meteorological variables on the estimation of the reference evapotranspiration.Journal of Hydrology,2001,243(3):192-204.