Arid
DOI10.1016/j.agrformet.2016.10.013
Estimation of latent heat flux over savannah vegetation across the North Australian Tropical Transect from multiple sensors and global meteorological data
Barraza, Veronica1; Restrepo-Coupe, Natalia2; Huete, Alfredo2; Grings, Francisco1; Beringer, Jason3,6; Cleverly, James4,6; Eamus, Derek4,5
通讯作者Barraza, Veronica
来源期刊AGRICULTURAL AND FOREST METEOROLOGY
ISSN0168-1923
EISSN1873-2240
出版年2017
卷号232页码:689-703
英文摘要

Latent heat flux (LE) and corresponding water loss in non-moisture-limited ecosystems are well correlated to radiation and temperature. By contrast, in savannahs and arid and semi-arid lands LE is mostly driven by available water and the vegetation exerts a strong control over the rate of transpiration. Therefore, LE models that use optical vegetation indices (VIs) to represent the vegetation component (transpiration as a function of surface conductance, G(s)) generally overestimate water fluxes in water limited ecosystems. In this study, we evaluated and compared optical and passive microwave index based retrievals of G(s) and LE derived using the Penman-Monteith (PM) formulation over the North Australian Tropical Transect (NATO. The methodology was evaluated at six eddy covariance (EC) sites from the OzFlux network. To parameterize the PM equation for retrievals of LE (PM-G(s)), a subset of G(s) values was derived from meteorological and EC flux observations and regressed against individual and combined satellite indices, from (1) MODIS AQUA: the Normalized Difference Water Index (NDWI) and the Enhanced Vegetation Index (EVI); and from (2) AMSR-E passive microwave: frequency index (FI), polarization index (PI), vegetation optical depth (VOD) and soil moisture (SM) products. Similarly, we combined optical and passive microwave indices (multi-sensor model) to estimate weekly G(s) values, and evaluated their spatial and temporal synergies. The multi-sensor approach explained 40-80% of LE variance at some sites, with root mean square errors (RMSE) lower than 20 W/m(2) and demonstrated better performance to other satellite-based estimates of LE. The optical indices represented potential G(s) associated with the phenological status of the vegetation (e.g. leaf area index, chlorophyll content) at finer spatial resolution. The microwave indices provided information about water availability and moisture stress (e.g. water content in leaves and shallow soil depths, atmospheric demand) at a high temporal resolution, thereby providing a scaling factor for potential G(s). We applied the newly proposed G(s) model to estimate LE at regional scale using global meteorological data. Our derivation could be extended to continental scales providing equally robust estimates of LE in arid and semi-arid biomes. A more accurate estimation of G(s) and LE across different savannah classes will improve the analysis of water use efficiency under drought conditions, which is of importance to climate change studies of water, carbon and energy cycling. (C) 2016 Elsevier B.V. All rights reserved.


英文关键词Microwave indices Optical indices Latent heat flux Surface conductance North Australian Tropical Transect OzFlux
类型Article
语种英语
国家Argentina ; Australia
收录类别SCI-E
WOS记录号WOS:000389089800057
WOS关键词ENERGY-BALANCE CLOSURE ; LEAF WATER STATUS ; STOMATAL CONDUCTANCE ; SURFACE CONDUCTANCE ; SPATIAL-PATTERNS ; SOIL-MOISTURE ; EVAPOTRANSPIRATION ; MODIS ; EVAPORATION ; CARBON
WOS类目Agronomy ; Forestry ; Meteorology & Atmospheric Sciences
WOS研究方向Agriculture ; Forestry ; Meteorology & Atmospheric Sciences
来源机构University of Western Australia
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/197095
作者单位1.UBA, IAFE, CONICET, Buenos Aires, DF, Argentina;
2.Univ Technol Sydney, Climate Change Cluster, Sydney, NSW 2007, Australia;
3.Univ Western Australia, Sch Earth & Environm, Crawley, WA 6009, Australia;
4.Univ Technol Sydney, Sch Life Sci, Sydney, NSW 2007, Australia;
5.Univ Western Australia, Terr Ecosyst Res Network, Australian Supersite Network, Crawley, WA 6009, Australia;
6.Univ Technol Sydney, Terr Ecosyst Res Network, Australian Supersite Network, POB 123, Broadway, NSW 2007, Australia
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Barraza, Veronica,Restrepo-Coupe, Natalia,Huete, Alfredo,et al. Estimation of latent heat flux over savannah vegetation across the North Australian Tropical Transect from multiple sensors and global meteorological data[J]. University of Western Australia,2017,232:689-703.
APA Barraza, Veronica.,Restrepo-Coupe, Natalia.,Huete, Alfredo.,Grings, Francisco.,Beringer, Jason.,...&Eamus, Derek.(2017).Estimation of latent heat flux over savannah vegetation across the North Australian Tropical Transect from multiple sensors and global meteorological data.AGRICULTURAL AND FOREST METEOROLOGY,232,689-703.
MLA Barraza, Veronica,et al."Estimation of latent heat flux over savannah vegetation across the North Australian Tropical Transect from multiple sensors and global meteorological data".AGRICULTURAL AND FOREST METEOROLOGY 232(2017):689-703.
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