DOI: 10.5194/hess-23-4891-2019
论文题名: Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data
作者: Armstrong R.N. ; Pomeroy J.W. ; Martz L.W.
刊名: Hydrology and Earth System Sciences
ISSN: 1027-5606
出版年: 2019
卷: 23, 期: 12 起始页码: 4891
结束页码: 4907
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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/162844
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Hydrology and Earth System Sciences,2019-01-01,23(12)