气候变化领域集成服务门户(CCPortal): Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data

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DOI	10.5194/hess-23-4891-2019
	Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data
	Armstrong R.N.; Pomeroy J.W.; Martz L.W.
发表日期	2019
ISSN	1027-5606
起始页码	4891
结束页码	4907
卷号	23 期号:12
英文摘要	Land surface evaporation has considerable spatial variability that is not captured by point-scale estimates calculated from meteorological data alone. Knowing how evaporation varies spatially remains an important issue for improving parameterisations of land surface schemes and hydrological models and various land management practices. Satellite-based and aerial remote sensing has been crucial for capturing moderate- to larger-scale surface variables to indirectly estimate evaporative fluxes. However, more recent advances for field research via unmanned aerial vehicles (UAVs) now allow for the acquisition of more highly detailed surface data. Integrating models that can estimate "actual" evaporation from higher-resolution imagery and surface reference data would be valuable to better examine potential impacts of local variations in evaporation on upscaled estimates. This study introduces a novel approach for computing a normalised ratiometric index from surface variables that can be used to obtain more-realistic distributed estimates of actual evaporation. For demonstration purposes the Granger-Gray evaporation model (Granger and Gray, 1989) was applied at a rolling prairie agricultural site in central Saskatchewan, Canada. Visible and thermal images and meteorological reference data required to parameterise the model were obtained at midday. Ratiometric indexes were computed for the key surface variables albedo and net radiation at midday. This allowed point observations of albedo and mean daily net radiation to be scaled across high-resolution images over a large study region. Albedo and net radiation estimates were within 5%-10% of measured values. A daily evaporation estimate for a grassed surface was 0.5mm (23%) larger than eddy covariance measurements. Spatial variations in key factors driving evaporation and their impacts on upscaled evaporation estimates are also discussed. The methods applied have two key advantages for estimating evaporation over previous remote-sensing approaches: (1) detailed daily estimates of actual evaporation can be directly obtained using a physically based evaporation model, and (2) analysis of more-detailed and more-reliable evaporation estimates may lead to improved methods for upscaling evaporative fluxes to larger areas. © 2019 Copernicus GmbH. All rights reserved.
语种	英语
scopus关键词	Antennas; Meteorology; Remote sensing; Solar radiation; Surface measurement; Aerial remote sensing; Eddy covariance measurements; High resolution image; Land management practices; Meteorological data; Remote sensing approaches; Remotely sensed imagery; Saskatchewan , Canada; Evaporation; albedo; evaporation; hydrological modeling; land management; remote sensing; satellite imagery; spatial variation; unmanned vehicle; upscaling; Canada; Saskatchewan
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159554
作者单位	Armstrong, R.N., Centre for Hydrology, University of Saskatchewan, Saskatoon, S7N 1K2, Canada, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Gatton Campus, Gatton, 4343, Australia; Pomeroy, J.W., Centre for Hydrology, University of Saskatchewan, Saskatoon, S7N 1K2, Canada; Martz, L.W., Centre for Hydrology, University of Saskatchewan, Saskatoon, S7N 1K2, Canada
推荐引用方式 GB/T 7714	Armstrong R.N.,Pomeroy J.W.,Martz L.W.. Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data[J],2019,23(12).
APA	Armstrong R.N.,Pomeroy J.W.,&Martz L.W..(2019).Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data.Hydrology and Earth System Sciences,23(12).
MLA	Armstrong R.N.,et al."Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data".Hydrology and Earth System Sciences 23.12(2019).