Uncertainty in evapotranspiration from land surface modeling, remote sensing, and GRACE satellites
Uncertainty in evapotranspiration from land surface modeling, remote sensing, and GRACE satellites
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DOI：
10.1002/2013wr014581
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发表时间：
2014-02-01
影响因子：
5.4
通讯作者：
Scanlon, Bridget R.
中科院分区：
文献类型：
--
作者：
Long, Di;Longuevergne, Laurent;Scanlon, Bridget R.
蒸散发（ET）产品的增殖值得对这些产品进行比较。研究目的是评估NLDAS-2中的Noah、Mosaic、VIC和SAC四种陆地表面模型（LSMs）、MODIS和AVHRR两种基于遥感的产品，以及GRACE从PRISM降水、监测径流和GRACE卫星总储水变化（TWSC）的水预算推断的ET输出的不确定性。利用三角帽法估算ET的不确定性，该方法不需要先验地知道ET的真实值。此外，将GRACE的TWSC或总储水异常（TWSA）与基于通量方法的TWSC或基于储水方法的TWSA的水预算估计进行了比较。分析使用来自美国中南部三个地区（潮湿干旱）的数据作为案例研究。LSM ET的不确定性最低（约为5毫米/月），MODIS或avhrr ET的不确定性中等（10-15毫米/月），grace推断ET的不确定性最高（20-30毫米/月）。在空间分辨率和不确定性之间存在一种权衡，较粗分辨率的LSM ET（约14 km）的不确定性较低，而较细分辨率的RS ET（约1-8 km）的不确定性较高。对于每个区域，TWSC水预算估算的不确定性均方根（RMS）约为grace衍生TWSC不确定性均方根（RMS）的一半。未来的蒸散发估算应考虑一种混合方法，将LSMs和卫星产品的优势结合起来，以限制不确定性。
Proliferation of evapotranspiration (ET) products warrants comparison of these products. The study objective was to assess uncertainty in ET output from four land surface models (LSMs), Noah, Mosaic, VIC, and SAC in NLDAS-2, two remote sensing-based products, MODIS and AVHRR, and GRACE-inferred ET from a water budget with precipitation from PRISM, monitored runoff, and total water storage change (TWSC) from GRACE satellites. The three cornered hat method, which does not require a priori knowledge of the true ET value, was used to estimate ET uncertainties. In addition, TWSC or total water storage anomaly (TWSA) from GRACE was compared with water budget estimates of TWSC from a flux-based approach or TWSA from a storage-based approach. The analyses were conducted using data from three regions (humid-arid) in the South Central United States as case studies. Uncertainties in ET are lowest in LSM ET (approximate to 5 mm/mo), moderate in MODIS or AVHRR-based ET (10-15 mm/mo), and highest in GRACE-inferred ET (20-30 mm/month). There is a trade-off between spatial resolution and uncertainty, with lower uncertainty in the coarser-resolution LSM ET (approximate to 14 km) relative to higher uncertainty in the finer-resolution (approximate to 1-8 km) RS ET. Root-mean-square (RMS) of uncertainties in water budget estimates of TWSC is about half of RMS of uncertainties in GRACE-derived TWSC for each of the regions. Future ET estimation should consider a hybrid approach that integrates strengths of LSMs and satellite-based products to constrain uncertainties.