CJCZO -- GIS/Map Data -- EEMT -- Jemez River Basin -- (2010-2010)

Yearly effective energy and mass transfer (EEMT) (MJ m−2 yr−1) was calculated for the Valles Calders, upper part of the Jemez River basin by summing the 12 monthly values. Effective energy and mass flux varies seasonally, especially in the desert southwestern United States where contemporary climate includes a bimodal precipitation distribution that concentrates in winter (rain or snow depending on elevation) and summer monsoon periods. This seasonality of EEMT flux into the upper soil surface can be estimated by calculating EEMT on a monthly basis as constrained by solar radiation (Rs), temperature (T), precipitation (PPT), and the vapor pressure deficit (VPD): EEMT = f(Rs,T,PPT,VPD). Here we used a multiple linear regression model to calculate the monthly EEMT that accounts for VPD, PPT, and locally modified T across the terrain surface. These EEMT calculations were made using data from the PRISM Climate Group at Oregon State University (www.prismclimate.org). Climate data are provided at an 800-m spatial resolution for input precipitation and minimum and maximum temperature normals and at a 4000-m spatial resolution for dew-point temperature (Daly et al., 2002). The PRISM climate data, however, do not account for localized variation in EEMT that results from smaller spatial scale changes in slope and aspect as occurs within catchments. To address this issue, these data were then combined with 10-m digital elevation maps to compute the effects of local slope and aspect on incoming solar radiation and hence locally modified temperature (Yang et al., 2007). Monthly average dew-point temperatures were computed using 10 yr of monthly data (2000–2009) and converted to vapor pressure. Precipitation, temperature, and dew-point data were resampled on a 10-m grid using spline interpolation. Monthly solar radiation data (direct and diffuse) were computed using ArcGIS Solar Analyst extension (ESRI, Redlands, CA) and 10-m elevation data (USGS National Elevation Dataset [NED] 1/3 Arc-Second downloaded from the National Map Seamless Server at seamless.usgs.gov). Locally modified temperature was used to compute the saturated vapor pressure, and the local VPD was estimated as the difference between the saturated and actual vapor pressures. The regression model was derived using the ISOHYS climate data set comprised of approximately 30-yr average monthly means for more than 300 weather stations spanning all latitudes and longitudes (IAEA).

针对赫梅斯河上游流域的瓦尔·卡尔德斯区域，通过累加12个月度数值，计算得到年有效能量与质量传输（effective energy and mass transfer, EEMT），单位为兆焦每平方米每年（MJ m⁻² yr⁻¹）。有效能量与质量通量具有显著季节变化特征，在美国西南部沙漠地区尤为明显——该区域当前气候呈现双峰型降水分布，降水分别集中于冬季（降水量形态随海拔变化，可为降雨或降雪）与夏季季风期。进入表层土壤的EEMT通量的这种季节变化特征，可通过基于月度尺度计算EEMT进行估算，计算过程受太阳辐射（solar radiation, Rs）、气温（temperature, T）、降水量（precipitation, PPT）以及水汽压亏缺（vapor pressure deficit, VPD）约束，其关系式为：EEMT = f(Rs,T,PPT,VPD)。本研究采用多元线性回归模型，计算月度EEMT，该模型可反映地表范围内VPD、PPT以及局地修正后气温的影响。本次EEMT计算所用数据源自俄勒冈州立大学PRISM气候组（PRISM Climate Group, www.prismclimate.org）。气候数据的空间分辨率为800米，用于输入降水量、日均最低与最高气温气候态；露点温度数据的空间分辨率为4000米（Daly等，2002）。但PRISM气候数据未考虑流域内发生的坡向与坡度小尺度空间变化所引发的EEMT局地变异。为解决该问题，本研究将上述数据与10米分辨率数字高程模型相结合，计算局地坡向与坡度对入射太阳辐射的影响，进而得到局地修正后的气温（Yang等，2007）。研究采用2000-2009年共10年的月度露点温度数据，计算月均露点温度，并将其转换为水汽压。通过样条插值法，将降水量、气温与露点温度数据重采样至10米分辨率网格。月度太阳辐射数据（包括直接辐射与散射辐射）通过ArcGIS太阳分析扩展模块（ArcGIS Solar Analyst Extension，ESRI，加利福尼亚州雷德兰兹）以及10米分辨率高程数据计算得到——该高程数据源自美国地质调查局国家高程数据集（USGS National Elevation Dataset, NED）1/3弧秒产品，下载自国家地图无缝服务器（National Map Seamless Server，seamless.usgs.gov）。利用局地修正后的气温计算饱和水汽压，并通过饱和水汽压与实际水汽压的差值估算局地水汽压亏缺。本研究所用回归模型基于ISOHYS气候数据集构建，该数据集涵盖全球各经纬度带的300余个气象站点的约30年月均气候数据（国际原子能机构, IAEA）。