Temporal and Spatial Distribution Characteristics of Potential Evapotranspiration and Its Sensitivity to Meteorological Factors in Guizhou Province

[Objective] The study aims to discuss the changes of potential evapotran- spiration and its sensitivity to meteorological factors in Guizhou Province, so as to provide important references for assessment of water resources, research of agri- cultural water conservancy and climate change. [Method] Temporal and spatial dis- tribution characteristics of potential evapotranspiration in Guizhou Province from 1961 to 2010 were analyzed, and the sensitivity of potential evapotranspiration to meteo- rological factors in Guizhou Province was studied through correlation analysis. [Re- sult] On the whole, potential evapotranspiration in Guizhou Province was higher in the southwest and the west compared with the northeast and the east. In various seasons, it was the highest in summer, followed by spring and autumn, while it was the lowest in winter. In recent 40 years, annual potential evapotranspiration showed an obvious decreasing trend in most stations of Guizhou Province. The main meteo- rological factors influencing changes of potential evapotranspiration in Guizhou Province were sunshine duration, daily maximum temperature, and daily average relative humidity. [Conclusion] Daily average temperature was not the main meteoro- logical factor affecting changes of potential evapotranspiration in Guizhou Province, while sunshine duration, daily maximum temperature, and daily average relative hu- midity had important effects on potential evapotranspiration in Guizhou Province.

Spatial and temporal variations and controlling factors of potential evapotranspiration in China:1956-2000

Based on the climatic data of 580 stations in China during 1956 and 2000, potential evapotranspiration are calculated using the Penman-Monteith Method recommended by FAO. The spatial and temporal distributions of the potential evapotranspiration over China and the temporal trends of the regional means for 10 major river basins and whole China are analyzed. Through a partial correlation analysis, the major climate factors which affect the temporal change of the potential evapotranspiration are analyzed. Major results are drawn as follows： 1） The seasonal and annual potential evapotranspiration for China as a whole and for most basins show decline tendencies during the past 45 years; for the Songhua River Basin there appears a slightly increasing trend. 2） Consequently, the annual potential evapotranspirations averaged over 1980-2000 are lower than those for the first water resources assessment （1956-1979） in most parts of China. Exceptions are found in some areas of Shandong Peninsula, western and middle basins of the rivers in Southwest China, Ningxia Hui Autonomous Region as well as the source regions of the Yangtze and Yellow rivers, which may have brought about disadvantages to the exploration and utilization of water resources. 3） Generally, sunshine duration, wind speed and relative humidity have greater impact on the potential evapotranspiration than temperature. Decline tendencies of sunshine duration and/or wind speed in the same period appear to be the major causes for the negative trend of the potential evapotranspiration in most areas.

Sensitivity of Potential Evapotranspiration Estimation to the Thornthwaite and Penman–Monteith Methods in the Study of Global Drylands

Drylands are among those regions most sensitive to climate and environmental changes and human-induced perturbations.The most widely accepted definition of the term dryland is a ratio,called the Surface Wetness Index(SWI),of annual precipitation to potential evapotranspiration(PET)being below 0.65.PET is commonly estimated using the Thornthwaite(PET Th)and Penman–Monteith equations(PET PM).The present study compared spatiotemporal characteristics of global drylands based on the SWI with PET Th and PET PM.Results showed vast differences between PET Th and PET PM;however,the SWI derived from the two kinds of PET showed broadly similar characteristics in the interdecadal variability of global and continental drylands,except in North America,with high correlation coefficients ranging from 0.58 to 0.89.It was found that,during 1901–2014,global hyper-arid and semi-arid regions expanded,arid and dry sub-humid regions contracted,and drylands underwent interdecadal fluctuation.This was because precipitation variations made major contributions,whereas PET changes contributed to a much lesser degree.However,distinct differences in the interdecadal variability of semi-arid and dry sub-humid regions were found.This indicated that the influence of PET changes was comparable to that of precipitation variations in the global dry–wet transition zone.Additionally,the contribution of PET changes to the variations in global and continental drylands gradually enhanced with global warming,and the Thornthwaite method was found to be increasingly less applicable under climate change.

Analysis on Temporal and Spatial Variation Characteristics of Potential Evapotranspiration in Guizhou Province

[Objective] The aim was to analyze temporal and spatial variation charac- teristics of potential evapotranspiration in Guizhou Province. [Method] According to information from 19 meteorological stations of Guizhou Province from 1960 to 2007, with the formulas of optimizational Penman-Monteith and SEBAL net radiation mod- el, the reference crop evapotranspiration ETo was calculated. Also with the spatial interpolation method of Arcgis 9.3, climate tendency rate statistics, K-M test, wavelet analysis and so on, the related regional differentiation and spatial and temporal change characteristics between meteorological factors from each monitoring station and ETo were analyzed. [Result] The results show that the correlation of potential evapotranspiration and meteorological factors in Guizhou Province demonstrates re- gional differentiation; there was no direct connection between the correlation of po- tential evapotranspiration and meteorological factors and the amount of meteorologi- cal factors in the year; there were 3 cycles in potential evapotranspiration, namely, 1 year, 5 years and 10 years, with 3 mutation points, respectively, in 1965, 1984 and 1999, mainly affected by air temperature, precipitation and solar radiation. [Conclusion] The research is of great significance in developing irrigation approach- es, adjusting agricultural structure and ecological construction.

Comparison of Ten Potential Evapotranspiration Models and Their Attribution Analyses for Ten Chinese Drainage Basins

Potential evapotranspiration(EPET)is usually calculated by empirical methods from surface meteorological variables,such as temperature,radiation and wind speed.The in-situ measured pan evaporation(ETpan)can also be used as a proxy for EPET.In this study,EPET values computed from ten models are compared with observed ETpan data in ten Chinese river basins for the period 1961−2013.The daily observed meteorological variables at 2267 stations are used as the input to those models,and a ranking scheme is applied to rank the statistical quantities(ratio of standard deviations,correlation coefficient,and ratio of trends)between ETpan and modeled EPET in different river basins.There are large deviations between the modeled EPET and the ETpan in both the magnitude and the annual trend at most stations.In eight of the basins(except for Southeast and Southwest China),ETpan shows decreasing trends with magnitudes ranging between−0.01 mm d−1 yr−1 and−0.03 mm d−1 yr−1,while the decreasing trends in modeled EPET are less than−0.01 mm d−1 yr−1.Inter comparisons among different models in different river basins suggest that PETHam1 is the best model in the Pearl River basin,PETHam2 outperforms other models in the Huaihe River,Yangtze River and Yellow River basins,and PETFAO is the best model for the remaining basins.Sensitivity analyses reveal that wind speed and sunshine duration are two important factors for decreasing EPET in most basins except in Southeast and Southwest China.The increasing EPET trend in Southeast China is mainly attributed to the reduced relative humidity.

Future changes of global potential evapotranspiration simulated from CMIP5 to CMIP6 models

This research evaluated the ability of different coupled climate models to simulate the historical variability of potential evapotranspiration(PET)for the time period 1979–2017 in phases 5 and 6 of the Coupled Model Intercomparison Project(CMIP5 and CMIP6,respectively).Their projected future changes of PET under two emission scenarios for the 21st century were also compared.Results show that PET has an increasing trend of 0.2–0.6 mm d-1/50 yr over most land surfaces and that there are clear regional differences.The future value of PET is higher in the CMIP6 multi-model simulations than in the CMIP5 ones under the same emissions scenario,possibly because CMIP6 models simulate stronger warming for a given forcing or scenario.The contributions of each individual climate driver to future changes in PET were examined and revealed that the surface vapor pressure deficit makes a major contribution to changes in PET.Shortwave radiation increases PET in most terrestrial regions,except for northern Africa,East Asia,South Asia,and Australia;the effect of longwave radiation is the opposite to that of shortwave radiation.The contribution of surface wind speed to PET is small,but results in a slight reduction.

Calculation of Forest Potential Evapotranspiration of Okinawa in Japan Using the Penman Equation

The northern area of Okinawa Island is a unique forest area in Japan, with a distinctive ecosystem and subtropical climate. The area is a central region of forestry in Okinawa Prefecture. However, quantitative evaluation of the effects of the forest environment is inadequate. The authors began meteorological observation of this forested area to address this situation by setting up a weather station in 2009. In this study, we performed research on one of the major factors of the water cycle in forest ecosystems, evapotranspiration. We calculate seasonal changes in potential evapotranspiration through analysis of data from our weather station in 2013, because all measurement elements were assembled. To calculate potential evapotranspiration, we used the Penman equation. We found that the potential evapotranspiration in this forest area was 1170.5 mm in 2013. The mean temperature in 2013 was 20.7°C, yearly average relative humidity was 84.7%, and average wind speed was 1.40 m/s. Regarding the amount of evapotranspiration in the forests of northern Okinawa Island, which has not been previously obtained, it has become possible to calculate the amount of potential evapotranspiration using the Penman equation.

Effect of Temporal Resolution of NDVI on Potential Evapotranspiration Estimation and Hydrological Model Performance

Normalized difference vegetation index (NDVI) data, obtained from remote sensing information, are essential in the Shuttleworth-Wallace (S-W) model for estimation of evapotranspiration. In order to study the effect of temporal resolution of NDVI on potential evapotranspiration (PET) estimation and hydrological model performance, monthly and 10-day NDVI data set were used to estimate potential evapotranspiration from January 1985 to December 1987 in Huangnizhuang catchment, Anhui Province, China. The differences of the two calculation results were analyzed and used to drive the block-wise use of the TOPMODEL with the Muskingum-Cunge routing (BTOPMC) model to test the effect on model performance. The results show that both annual and monthly PETs estimated by 10-day NDVI are lower than those estimated by monthly NDVI. Annual PET from the vegetation root zone (PETr) lowers 9.77%-13.64% and monthly PETr lowers 3.28%-17.44% in the whole basin. PET from the vegetation interception (PETi) shows the same trend as PETr. In addition, temporal resolution of NDVI has more effect on PETr in summer and on PETi in winter. The correlation between PETr as estimated by 10-day NDVI and pan measurement (R2= 0.835) is better than that between monthly NDVI and pan measurement (R2 = 0.775). The two potential evapotranspiration estimates were used to drive the BTOPMC model and calibrate parameters, and model performance was found to be similar. In summary, the effect of temporal resolution of NDVI on potential evapotranspiration estimation is significant, but trivial on hydrological model performance.

Assessing the spatiotemporal distributions of evapotranspiration in the Three Gorges Reservoir Region of China using remote sensing data

Evapotranspiration(ET) is a critical component of the global hydrological cycle, and it has a large impact on water resource management as it affects the availability of freshwater resources. It is important to understand the hydrological cycle for the water resources planning and management. This study used Moderate Resolution Imaging Spectroradiometer(MODIS) satellite derived ET, and potential evapotranspiration(PET) and Tropical Rainfall Measuring Mission(TRMM) satellite derived precipitation datasets to assess the spatial and temporal distributions of ET, PET, and precipitation during the study period at Three Gorges Reservoir(TGR) region. Based on the topographic variations and land-use/land-cover distributions, the study region which includes five counties of Hubei Province and nineteen counties of Chongqing Municipality was divided into four study zones. The ET and precipitation data were evaluated using in situ observations. The ET, PET, and precipitation data were compared to analyze the spatial and long-term(2001-2016) temporal distributions of average annual ET, PET, and precipitation, and to understand the relationships between them in the study region. The results showed that each selected zone had highest ET at the counties with the Yangtze River passing through whereas lowest at the counties which were located away from the river. Results also showed increasing trends in ET and PET from south-west to north-east in the study region. Analysis showed TGR had a significant impact on spatial and temporal distributions of ET and PET in the study region. Therefore, this study helps to understand the impact of TGR on spatial and temporal distributions of ET and PET during and after the construction.

Future changes in rainfall, temperature and reference evapotranspiration in the central India by least square support vector machine

Climate change affects the environment and natural resources immensely. Rainfall, temperature and evapotranspiration are major parameters of climate affecting changes in the environment. Evapotrans- piration plays a key role in crop production and water balance of a region, one of the major parameters affected by climate change. The reference evapotranspiration or ETo is a calculated parameter used in this research. In the present study, changes in the future rainfall, minimum and maximum temperature, and ETo have been shown by downscaling the HadCM3 （Hadley Centre Coupled Model version 3） model data. The selected study area is located in a part of the Narmada river basin area in Madhya Pradesh in central India. The downscaled outputs of projected rainfall, ETo and temperatures have been shown for the 21st century with the HADCM3 data of A2 scenario by the Least Square Support Vector Machine （LS-SVM） model. The efficiency of the LS-SVM model was measured by different statistical methods. The selected predictors show considerable correlation with the rainfall and temperature and the application of this model has been done in a basin area which is an agriculture based region and is sensitive to the change of rainfall and temperature. Results showed an increase in the future rainfall, temperatures and ETo. The temperature increase is projected in the high rise of minimum temperature in winter time and the highest increase in maximum temperature is projected in the pre-monsoon season or from March to May. Highest increase is projected in the 2080s in 2081-2091 and 2091-2099 in maximum temperature and 2091-2099 in minimum temperature in all the stations. Winter maximum temperature has been observed to have increased in the future. High rainfall is also observed with higher ETo in some decades. Two peaks of the increase are observed in ETo in the April-May and in the October. Variation in these parameters due to climate change might have an impact on the future water resource of the study area, which is mainly an agricultural based region, and will help in proper planning and management.

Effect of Sustained Deficit Irrigation on Stem Water Potential of Navel Oranges in Jordan Valley

Research was conducted to find the relationship between deficit irrigation treatments （DIT） and stems water potential. The study was conducted on 14 years old navel orange trees grafted on sour oranges for the growing season 2006/2007 at a private farm in the Northern part of Jordan Valley （latitude： 32° 50′ N, longitude： 32° 50′ E, altitude： -254 m）. Three levels of irrigation treatments （IT） were applied; namely 100%, 75% and 50% of reference evapotranspiration, representing over irrigation （OIT）, full irrigation （FIT）, and deficit irrigation （DIT）, respectively. A drip irrigation using one irrigation source line with drippers spaced 0.5 m having average discharge of 2.3 L/hr at pressure 1.5 bar, was used. Stem water potential （SWP） at 100% over irrigation treatment （OIT） of navel orange trees had less negative value during the irrigation seasons （-1.57 MPa）, whereas the highest negative value （-2.17 MPa） occurred at 50% deficit irrigation treatment （DIT）.

Division of desertification climate types and determination of potential range of desertification in China

Distribution of desertification climate types in China was analyzed using Thornthwaite's method on calculating potential evapotranspiration (PE), according to the definition provided by the United Nations Convention, by employing meteorological records from 1864 stations in China. The annual PE and the humidity indices were calculated for every station, based on which a distribution map of HI was constructed. The potential range of desertification in China was obtained for the first time, about 3.32 million km2 and makes up about 34.6 percent of the country. The distribution map of HI was compared with the vegetation map of China and the precipitation map of China respectively. In eastern and northern China, the distribution of climate types is basically acceptable, but for QinghaiTibetan Plateau, where Thornthwaite's method on calculating PE is not quite suitable, the isopleths are deviated to the northern side and the potential range of desertification is smaller than expected.

Shortwave radiation balance modulates potential evapotranspiration over China

Shortwave radiation is an influential driver of global hydrological cycle,as its variation will alter evapotranspiration(ET).While climate change discussion extensively examined ET response to temperature,wind speed and land use/cover variations,little is known about the contribution of shortwave radiation balance on ET partly because of data availability.In this study,we applied the newly-released Global LAnd Surface Satellite(GLASS)products to detect changes in shortwave radiation and albedo for 2003–2018 over China,and quantified their contributions on potential evapotranspiration(PET)which is the upper limit of ET and generally the basis to estimate it.The results showed that downward shortwave radiation declined,together with a slight decrease in albedo,causing a decrease of net shortwave radiation.While climate change affected PET,the decreased net shortwave radiation reduced PET during the period.We identified a hotspot area in the north China plain that is one of the main agricultural production regions,as the radiation balance induced a contrasting effect on PET for the warm and the cold seasons.Our study indicates that it is important to consider shortwave radiation balance when estimating PET and ET to make reliable evaluation of climate change on hydrological cycle and ecosystem response.

2005-2020年亚洲中部干旱区生态站月潜在蒸散量数据集

潜在蒸散表征大气蒸发能力,是衡量区域蒸发能力的重要指标,也是评价气候干旱程度变化、水资源供需平衡、植被耗水量等的关键参数。在收集中亚生态系统监测网络12个生态站和中国生态系统研究网络(CERN)11个位于西北干旱区生态站的气象观测数据基础上,经过数据质量控制与插补,采用Penman-Monteith模型计算潜在蒸散量,生成了2005-2020年亚洲中部干旱区生态站月潜在蒸散量数据集。本数据集时间序列较长、覆盖多种生态系统类型,可作为亚洲中部干旱问题研究的基础数据、模型输入数据、模拟结果验证数据等,也可为该区域水资源的合理开发与利用、生态环境保护等方面研究提供数据支撑。

多源潜在蒸散发产品在雅鲁藏布江流域的适用性评估与融合

基于2001—2018年监测站点观测的蒸发皿数据,分别在站点尺度和流域尺度上对GLEAM、MOD16A2、GLDAS_Noah和ERA5共4种遥感潜在蒸散发产品进行评估,选出适应性较好的3种遥感产品,运用Triple Collocation方法进行融合,并分析其时空变化特征。结果表明:在站点尺度上,ERA5遥感产品相关性较为显著(相关系数CC=0.72),精确度最高(相对偏差Bias=-22.48%,均方根误差RMSE=39.24 mm/月),更适用于雅鲁藏布江流域,MOD16A2和GLDAS_Noah次之;MOD16A2、GLDAS_Noah和ERA5分别占融合数据PET_(TC)的31.12%、30.64%和38.24%,对比PET_(TC)与3种遥感产品,PET_(TC)融合数据在流域内精度有所提高;融合数据PET_(TC)的潜在蒸散发峰值出现在2009年,雅鲁藏布江流域多年平均潜在蒸散发呈现从中部向上、下游逐渐减小的趋势,在流域东南角出现潜在蒸散发量最大值。在雅鲁藏布江流域内获得更精准的潜在蒸散发并揭示其变化规律,可为研究流域水资源的供需平衡和生态系统的稳定性提供数据支撑。

1979—2021年新疆昆仑山北坡潜在蒸散时空变化研究

蒸散是陆面水循环的重要环节,在高寒干旱环境中表现更加复杂。新疆昆仑山北坡位于青藏高原北缘,山区实地气象观测匮乏,对潜在蒸散的认识也有待加强。通过Mann-Kendall检验和经验正交函数分析了1979—2021年新疆昆仑山北坡潜在蒸散的时空变化特征,比较了各流域的变化趋势,并且分析了潜在蒸散与其他气象要素的关系。结果表明:(1)新疆昆仑山北坡年均潜在蒸散为733.5 mm,从塔里木盆地南缘向南呈现出逐渐减小的空间变化趋势。(2)1979—2021年潜在蒸散总体呈波动上升趋势,线性变化率为8.7 mm·(10a)^(-1),其中2007年以前呈上升趋势,2007年后有下降趋势。(3)在喀什噶尔河流域、叶尔羌河流域、和田河流域、克里雅河流域、车尔臣河流域以及库木库里盆地6个流域中,车尔臣河流域年均潜在蒸散最高(810.8 mm),其线性变化率也最大(11.4 mm·(10a)^(-1)),和田河流域和克里雅河流域潜在蒸散的升高趋势相对较小,线性变化率分别为4.9 mm·(10a)^(-1)和5.0 mm·(10a)^(-1)。未来仍应加强新疆昆仑山北坡高海拔区域的水文气象观测,以便明确全球变化背景下的水文不确定性。

六盘山华北落叶松和白桦林日蒸腾对环境因子的响应差异

【目的】准确量化半干旱区典型人工林的蒸腾特征及其对气象因子和土壤水分的响应规律,探究其水分利用策略的差异,为该区域的林水综合管理提供理论依据。【方法】2022年5—10月,在六盘山半干旱区叠叠沟小流域选取当地主要的造林树种华北落叶松和白桦,各布设1个面积30 m×30 m的固定样地,每个样地选取12株不同胸径的样树,连续测定树干液流密度、气象因子和0~60 cm土层的土壤含水量,分析华北落叶松和白桦人工林蒸腾特征及其对潜在蒸散(PET)和土壤相对可利用水分(REW)的响应差异。【结果】1)7—10月华北落叶松和白桦人工林的日均蒸腾量分别为0.63和0.54 mm·d^(-1),前者比后者高0.09 mm·d^(-1);华北落叶松和白桦林分日蒸腾量随着月份变化均呈先增后减的变化趋势,在7月均达到最大值,分别为1.38和1.45 mm·d^(-1)。2)2种人工林的日蒸腾量对PET的响应均符合指数函数关系,即日蒸腾量随PET增大呈先增大后趋于稳定,但变化趋势在不同REW之间有差别;华北落叶松林分日蒸腾量随PET增长的速率在REW<0.3时较低,在REW>0.3后则迅速升高,且不同REW之间差距很小;而白桦林分日蒸腾量随PET增长的速率持续增大,且比较均匀。3)2种人工林的日蒸腾量对REW的响应也均符合指数函数关系,但变化趋势在不同PET之间有差别;华北落叶松林分蒸腾量随REW增长的速率在PET<2 mm·d^(-1)时较低,在PET>2 mm·d^(-1)后则迅速升高,且不同PET之间差距很小;相比之下,白桦人工林日蒸腾量随REW增大而升高的变化在整个PET变化范围内都比较均匀,且增长速率持续增大。【结论】华北落叶松林分日蒸腾量对PET和REW的响应明显比白桦林更敏感。华北落叶松林分日蒸腾量在PET<2 mm·d^(-1)或REW<0.3时明显高于白桦,但在PET>2 mm·d^(-1)或REW>0.3后迅速升高到其最大值附近并随PET或REW升高保持稳定,而白桦林分日蒸腾量表现为相对均匀地逐渐趋于其最大值。这说明在水分受限的半干旱区,华北落叶松林的蒸腾耗水量高于白桦林,且白桦林蒸腾受干旱期土壤水分的限制更明显。

河西走廊潜在蒸散发时空格局变化与气象因素的关系

蒸散发过程影响因素众多,潜在蒸散发(ET_0)与气象变量交互作用复杂,亟需揭示ET_0变化对气象变量的响应机理。基于河西走廊及周边21个气象站点气象资料,采用定性定量分析方法,以河西走廊整体及3分区2个空间尺度,揭示ET_0时空变化规律,明确ET_0对各气象因素变化敏感性及贡献。结果表明:(1)河西走廊及分区ET_0均呈显著波动上升趋势(Z>1.98),线性变化率2.94 mm·a~(-1),且黑河分区变化最明显。(2)ET_0由东南向西北递增变化,中东部石羊河分区(1003.78 mm)、黑河分区(1031.30 mm)较小,西部疏勒河分区(1171.89 mm)较大。(3)河西走廊ET_0对气象因素变化敏感性排序为相对湿度(RH)、日最高气温(T_(max))、日照时数(n)、平均风速(u)、日降水量(P),ET_0对RH减少最敏感,对P变化最不敏感。(4)u增大是造成河西走廊ET_0增大的主要原因,其次是RH减少、T_(max)升高、n增加。(5)疏勒河分区、黑河分区、石羊河分区ET_0呈增加变化,贡献最大因素分别为T_(max)(5.13%)、u(8.22%)、T_(max)(5.97%),贡献最小因素为n。气候因素中的风速和气温变化是河西走廊地区ET_0变化不容忽视的重要影响因素,研究成果对合理规划农田灌溉用水和提高农业水资源利用效率意义重大。

1956—2019年元谋干热河谷潜在蒸散发的变化及影响因素

为探究元谋干热河谷地区潜在蒸散发变化特征及其影响因子,通过应用彭曼蒙特斯模型、曼-肯德尔突变检验、气候倾向率和距平相关方法,分时段分析1956—2019年逐日气象要素值。结果表明:元谋干热河谷地区潜在蒸散发整体呈极显著下降的趋势,年度潜在蒸散发在1982年发生突变;各季潜在蒸散发变化明显,变化速率从大到小依次为3—5月、12月—次年2月、6—8月、9—11月;除1956—1982年12月—次年2月,1982—2019年9—11月、12月—次年2月潜在蒸散发有所增长外,剩下时段都呈减少趋势,1982年为各季的突变点。潜在蒸散发转折点为1982年;1982年前,年度潜在蒸散发距平占主导;1982年后,负距平占据主导,2008、2015年发生两次较大的波动。元谋干热河谷地区年潜在蒸散发变化主要取决于日照时间、气温和平均相对湿度;各季潜在蒸散发主要是由各气象要素共同作用的结果,且具有季节性差异;1982年以前,6—8月、9—11月潜在蒸散发的减少和12月—次年2月潜在蒸散发的增加仅与平均风速的减弱有关。

1981—2018年吉林省玉米水分盈亏及旱涝时空分布

吉林省作为我国玉米主产区和重要的商品粮基地,明确吉林省玉米水分盈亏指数及旱涝灾害的时空分布特征,有助于提高农业生产的稳定性和抗灾能力。该文采用吉林省逐日气象站点数据,通过计算月尺度下的潜在蒸散量,构建水分盈亏指数来分析吉林省潜在蒸散量和旱涝灾害的时空分布特征,运用趋势分析法和小波分析法来探究水分盈亏指数的趋势性及周期性变化。结果表明:多年平均潜在蒸散量和各月份平均潜在蒸散量均有由西北至东南逐渐递减的趋势,5—9月潜在蒸散量分别占生长周期内总平均潜在蒸散量的26.3%、24.5%、21.1%、16.8%和11.3%。5月和9月发生中旱及以上频率大于50%的地区主要位于白城市西部,四平市西部和长春市中部地区。8月和9月中涝及以上频率高值区位于吉林省东部及东南部地区。