Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods
Water use efficiency (WUE) is a key index for understanding the ecosystem of carbon–water coupling. The undistinguishable carbon–water coupling mechanism and uncertainties of indirect methods by remote sensing products and process models render challenges for WUE remote sensing. In this paper, curre...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-06-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/13/12/2393 |
| _version_ | 1797529633207353344 |
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| author | Wanyuan Cai Sana Ullah Lei Yan Yi Lin |
| author_facet | Wanyuan Cai Sana Ullah Lei Yan Yi Lin |
| author_sort | Wanyuan Cai |
| collection | DOAJ |
| description | Water use efficiency (WUE) is a key index for understanding the ecosystem of carbon–water coupling. The undistinguishable carbon–water coupling mechanism and uncertainties of indirect methods by remote sensing products and process models render challenges for WUE remote sensing. In this paper, current progress in direct and indirect methods of WUE estimation by remote sensing is reviewed. Indirect methods based on gross primary production (GPP)/evapotranspiration (ET) from ground observation, processed models and remote sensing are the main ways to estimate WUE in which carbon and water cycles are independent processes. Various empirical models based on meteorological variables and remote sensed vegetation indices to estimate WUE proved the ability of remotely sensed data for WUE estimating. The analytical model provides a mechanistic opportunity for WUE estimation on an ecosystem scale, while the hypothesis has yet to be validated and applied for the shorter time scales. An optimized response of canopy conductance to atmospheric vapor pressure deficit (VPD) in an analytical model inverted from the conductance model has been also challenged. Partitioning transpiration (T) and evaporation (E) is a more complex phenomenon than that stated in the analytic model and needs a more precise remote sensing retrieval algorithm as well as ground validation, which is an opportunity for remote sensing to extrapolate WUE estimation from sites to a regional scale. Although studies on controlling the mechanism of environmental factors have provided an opportunity to improve WUE remote sensing, the mismatch in the spatial and temporal resolution of meteorological products and remote sensing data, as well as the uncertainty of meteorological reanalysis data, add further challenges. Therefore, improving the remote sensing-based methods of GPP and ET, developing high-quality meteorological forcing datasets and building mechanistic remote sensing models directly acting on carbon–water cycle coupling are possible ways to improve WUE remote sensing. Improvement in direct WUE remote sensing methods or remote sensing-driven ecosystem analysis methods can promote a better understanding of the global ecosystem carbon–water coupling mechanisms and vegetation functions–climate feedbacks to serve for the future global carbon neutrality. |
| first_indexed | 2024-03-10T10:16:31Z |
| format | Article |
| id | doaj.art-6122d730fa944cd1a429b3898b9f45bd |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T10:16:31Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-6122d730fa944cd1a429b3898b9f45bd2023-11-22T00:46:21ZengMDPI AGRemote Sensing2072-42922021-06-011312239310.3390/rs13122393Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation MethodsWanyuan Cai0Sana Ullah1Lei Yan2Yi Lin3Beijing Key Lab of Spatial Information Integration and 3S Application, Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaBeijing Key Lab of Spatial Information Integration and 3S Application, Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaBeijing Key Lab of Spatial Information Integration and 3S Application, Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaBeijing Key Lab of Spatial Information Integration and 3S Application, Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaWater use efficiency (WUE) is a key index for understanding the ecosystem of carbon–water coupling. The undistinguishable carbon–water coupling mechanism and uncertainties of indirect methods by remote sensing products and process models render challenges for WUE remote sensing. In this paper, current progress in direct and indirect methods of WUE estimation by remote sensing is reviewed. Indirect methods based on gross primary production (GPP)/evapotranspiration (ET) from ground observation, processed models and remote sensing are the main ways to estimate WUE in which carbon and water cycles are independent processes. Various empirical models based on meteorological variables and remote sensed vegetation indices to estimate WUE proved the ability of remotely sensed data for WUE estimating. The analytical model provides a mechanistic opportunity for WUE estimation on an ecosystem scale, while the hypothesis has yet to be validated and applied for the shorter time scales. An optimized response of canopy conductance to atmospheric vapor pressure deficit (VPD) in an analytical model inverted from the conductance model has been also challenged. Partitioning transpiration (T) and evaporation (E) is a more complex phenomenon than that stated in the analytic model and needs a more precise remote sensing retrieval algorithm as well as ground validation, which is an opportunity for remote sensing to extrapolate WUE estimation from sites to a regional scale. Although studies on controlling the mechanism of environmental factors have provided an opportunity to improve WUE remote sensing, the mismatch in the spatial and temporal resolution of meteorological products and remote sensing data, as well as the uncertainty of meteorological reanalysis data, add further challenges. Therefore, improving the remote sensing-based methods of GPP and ET, developing high-quality meteorological forcing datasets and building mechanistic remote sensing models directly acting on carbon–water cycle coupling are possible ways to improve WUE remote sensing. Improvement in direct WUE remote sensing methods or remote sensing-driven ecosystem analysis methods can promote a better understanding of the global ecosystem carbon–water coupling mechanisms and vegetation functions–climate feedbacks to serve for the future global carbon neutrality.https://www.mdpi.com/2072-4292/13/12/2393ecosystem water use efficiencycarbon–water cycle couplingflux measurementremote sensingcarbon neutrality |
| spellingShingle | Wanyuan Cai Sana Ullah Lei Yan Yi Lin Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods Remote Sensing ecosystem water use efficiency carbon–water cycle coupling flux measurement remote sensing carbon neutrality |
| title | Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods |
| title_full | Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods |
| title_fullStr | Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods |
| title_full_unstemmed | Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods |
| title_short | Remote Sensing of Ecosystem Water Use Efficiency: A Review of Direct and Indirect Estimation Methods |
| title_sort | remote sensing of ecosystem water use efficiency a review of direct and indirect estimation methods |
| topic | ecosystem water use efficiency carbon–water cycle coupling flux measurement remote sensing carbon neutrality |
| url | https://www.mdpi.com/2072-4292/13/12/2393 |
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