Using long‐term water balances to parameterize surface conductances and calculate evaporation at 0.05° spatial resolution
Using long‐term water balances to parameterize surface conductances and calculate evaporation at 0.05° spatial resolution
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DOI：
10.1029/2009wr008716
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发表时间：
2010-05
影响因子：
5.4
通讯作者：
Yongqiang Zhang;R. Leuning;L. Hutley;J. Beringer;I. McHugh;J. Walker
中科院分区：
文献类型：
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作者：
Yongqiang Zhang;R. Leuning;L. Hutley;J. Beringer;I. McHugh;J. Walker
使用 Penman-Monteith (PM) 能量平衡方程、网格气象学和简单的表面电导生物物理模型计算连续 8 天间隔内的平均蒸发量和 0.05°（∼5 km）空间分辨率。该电导是土壤表面蒸发、叶面积指数、吸收的光合有效辐射、大气水蒸气压差和最大气孔导度 (gsx) 的函数。本文的新颖之处在于使用“Budyko 曲线”水文气象模型来估计平均年蒸发率，从而估计澳大利亚大陆每个网格单元的 gsx 的唯一值。首先，使用 285 个测量流域的长期水平衡来校准水文气象模型。其次，将网格气象数据与校准的水文气象模型一起使用来估计每个网格单元的年平均蒸发量（）。第三，调整每个像元的 gsx 值，使其等于使用 PM 方程计算的值与水文气象模型计算的值。这关闭了年度水平衡，但允许 PM 方程为蒸发提供比年度水平衡模型更精细的时间分辨率。使用遥感叶面积指数、参数化 PM 方程获得的 8 天平均蒸发率与 2000 年至 2008 年期间澳大利亚四个涡流协方差通量站点的实际蒸发观测值之间具有令人满意的一致性（0.49 < R2 < 0.80）。蒸发产品可用于水文模型校准，以改进未计量流域的径流预测研究。
Evaporation from the land surface, averaged over successive 8 day intervals and at 0.05° (∼5 km) spatial resolution, was calculated using the Penman‐Monteith (PM) energy balance equation, gridded meteorology, and a simple biophysical model for surface conductance. This conductance is a function of evaporation from the soil surface, leaf area index, absorbed photosynthetically active radiation, atmospheric water vapor pressure deficit, and maximum stomatal conductance (gsx). The novelty of this paper is the use of a “Budyko‐curve” hydrometeorological model to estimate mean annual evaporation rates and hence a unique value of gsx for each grid cell across the Australian continent. First, the hydrometeorological model was calibrated using long‐term water balances from 285 gauged catchments. Second, gridded meteorological data were used with the calibrated hydrometeorological model to estimate mean annual average evaporation () for each grid cell. Third, the value of gsx for each cell was adjusted to equate calculated using the PM equation with from the hydrometeorological model. This closes the annual water balance but allows the PM equation to provide a finer temporal resolution for evaporation than is possible with an annual water balance model. There was satisfactory agreement (0.49 < R2 < 0.80) between 8 day average evaporation rates obtained using remotely sensed leaf area indices, the parameterized PM equation, and observations of actual evaporation at four Australian eddy covariance flux sites for the period 2000–2008. The evaporation product can be used for hydrological model calibration to improve runoff prediction studies in ungauged catchments.