The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Ke Zhang - One of the best experts on this subject based on the ideXlab platform.
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a review of remote sensing based actual Evapotranspiration estimation
Wiley Interdisciplinary Reviews: Water, 2016Co-Authors: Ke Zhang, John S Kimball, Steven W. RunningAbstract:Evapotranspiration is a major component of the global water cycle and provides a critical nexus between terrestrial water, carbon and surface energy exchanges. Evapotranspiration is inherently difficult to measure and predict especially at large spatial scales. Remote sensing provides a cost-effective method to estimate Evapotranspiration at regional to global scales. In the past three decades a large number of studies on remote sensing based Evapotranspiration estimation have emerged. This review summarizes the basic theories underpinning current remote sensing based Evapotranspiration estimation methods. It also lays out the development history of these methods and compares their advantages and limitations. Several key directions for further study are identified and discussed, including identification of uncertainty sources in remote sensing Evapotranspiration models, merging of different remote sensing methods, application of data assimilation and fusion techniques in producing robust Evapotranspiration estimates, and utilization of multi-source remote sensing data and latest sensor technologies. Further advances in the remote sensing of Evapotranspiration will enhance capabilities for monitoring of the global water and energy cycles, including water availability and ecosystem responses and feedbacks to climate change and human impacts. WIREs Water 2016, 3:834–853. doi: 10.1002/wat2.1168 For further resources related to this article, please visit the WIREs website.
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A review of remote sensing based actual Evapotranspiration estimation: A review of remote sensing Evapotranspiration
Wiley Interdisciplinary Reviews: Water, 2016Co-Authors: Ke Zhang, John S Kimball, Steven W. RunningAbstract:Evapotranspiration is a major component of the global water cycle and provides a critical nexus between terrestrial water, carbon and surface energy exchanges. Evapotranspiration is inherently difficult to measure and predict especially at large spatial scales. Remote sensing provides a cost-effective method to estimate Evapotranspiration at regional to global scales. In the past three decades a large number of studies on remote sensing based Evapotranspiration estimation have emerged. This review summarizes the basic theories underpinning current remote sensing based Evapotranspiration estimation methods. It also lays out the development history of these methods and compares their advantages and limitations. Several key directions for further study are identified and discussed, including identification of uncertainty sources in remote sensing Evapotranspiration models, merging of different remote sensing methods, application of data assimilation and fusion techniques in producing robust Evapotranspiration estimates, and utilization of multi-source remote sensing data and latest sensor technologies. Further advances in the remote sensing of Evapotranspiration will enhance capabilities for monitoring of the global water and energy cycles, including water availability and ecosystem responses and feedbacks to climate change and human impacts. WIREs Water 2016, 3:834–853. doi: 10.1002/wat2.1168 For further resources related to this article, please visit the WIREs website.
Steven W. Running - One of the best experts on this subject based on the ideXlab platform.
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a review of remote sensing based actual Evapotranspiration estimation
Wiley Interdisciplinary Reviews: Water, 2016Co-Authors: Ke Zhang, John S Kimball, Steven W. RunningAbstract:Evapotranspiration is a major component of the global water cycle and provides a critical nexus between terrestrial water, carbon and surface energy exchanges. Evapotranspiration is inherently difficult to measure and predict especially at large spatial scales. Remote sensing provides a cost-effective method to estimate Evapotranspiration at regional to global scales. In the past three decades a large number of studies on remote sensing based Evapotranspiration estimation have emerged. This review summarizes the basic theories underpinning current remote sensing based Evapotranspiration estimation methods. It also lays out the development history of these methods and compares their advantages and limitations. Several key directions for further study are identified and discussed, including identification of uncertainty sources in remote sensing Evapotranspiration models, merging of different remote sensing methods, application of data assimilation and fusion techniques in producing robust Evapotranspiration estimates, and utilization of multi-source remote sensing data and latest sensor technologies. Further advances in the remote sensing of Evapotranspiration will enhance capabilities for monitoring of the global water and energy cycles, including water availability and ecosystem responses and feedbacks to climate change and human impacts. WIREs Water 2016, 3:834–853. doi: 10.1002/wat2.1168 For further resources related to this article, please visit the WIREs website.
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A review of remote sensing based actual Evapotranspiration estimation: A review of remote sensing Evapotranspiration
Wiley Interdisciplinary Reviews: Water, 2016Co-Authors: Ke Zhang, John S Kimball, Steven W. RunningAbstract:Evapotranspiration is a major component of the global water cycle and provides a critical nexus between terrestrial water, carbon and surface energy exchanges. Evapotranspiration is inherently difficult to measure and predict especially at large spatial scales. Remote sensing provides a cost-effective method to estimate Evapotranspiration at regional to global scales. In the past three decades a large number of studies on remote sensing based Evapotranspiration estimation have emerged. This review summarizes the basic theories underpinning current remote sensing based Evapotranspiration estimation methods. It also lays out the development history of these methods and compares their advantages and limitations. Several key directions for further study are identified and discussed, including identification of uncertainty sources in remote sensing Evapotranspiration models, merging of different remote sensing methods, application of data assimilation and fusion techniques in producing robust Evapotranspiration estimates, and utilization of multi-source remote sensing data and latest sensor technologies. Further advances in the remote sensing of Evapotranspiration will enhance capabilities for monitoring of the global water and energy cycles, including water availability and ecosystem responses and feedbacks to climate change and human impacts. WIREs Water 2016, 3:834–853. doi: 10.1002/wat2.1168 For further resources related to this article, please visit the WIREs website.
John S Kimball - One of the best experts on this subject based on the ideXlab platform.
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a review of remote sensing based actual Evapotranspiration estimation
Wiley Interdisciplinary Reviews: Water, 2016Co-Authors: Ke Zhang, John S Kimball, Steven W. RunningAbstract:Evapotranspiration is a major component of the global water cycle and provides a critical nexus between terrestrial water, carbon and surface energy exchanges. Evapotranspiration is inherently difficult to measure and predict especially at large spatial scales. Remote sensing provides a cost-effective method to estimate Evapotranspiration at regional to global scales. In the past three decades a large number of studies on remote sensing based Evapotranspiration estimation have emerged. This review summarizes the basic theories underpinning current remote sensing based Evapotranspiration estimation methods. It also lays out the development history of these methods and compares their advantages and limitations. Several key directions for further study are identified and discussed, including identification of uncertainty sources in remote sensing Evapotranspiration models, merging of different remote sensing methods, application of data assimilation and fusion techniques in producing robust Evapotranspiration estimates, and utilization of multi-source remote sensing data and latest sensor technologies. Further advances in the remote sensing of Evapotranspiration will enhance capabilities for monitoring of the global water and energy cycles, including water availability and ecosystem responses and feedbacks to climate change and human impacts. WIREs Water 2016, 3:834–853. doi: 10.1002/wat2.1168 For further resources related to this article, please visit the WIREs website.
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A review of remote sensing based actual Evapotranspiration estimation: A review of remote sensing Evapotranspiration
Wiley Interdisciplinary Reviews: Water, 2016Co-Authors: Ke Zhang, John S Kimball, Steven W. RunningAbstract:Evapotranspiration is a major component of the global water cycle and provides a critical nexus between terrestrial water, carbon and surface energy exchanges. Evapotranspiration is inherently difficult to measure and predict especially at large spatial scales. Remote sensing provides a cost-effective method to estimate Evapotranspiration at regional to global scales. In the past three decades a large number of studies on remote sensing based Evapotranspiration estimation have emerged. This review summarizes the basic theories underpinning current remote sensing based Evapotranspiration estimation methods. It also lays out the development history of these methods and compares their advantages and limitations. Several key directions for further study are identified and discussed, including identification of uncertainty sources in remote sensing Evapotranspiration models, merging of different remote sensing methods, application of data assimilation and fusion techniques in producing robust Evapotranspiration estimates, and utilization of multi-source remote sensing data and latest sensor technologies. Further advances in the remote sensing of Evapotranspiration will enhance capabilities for monitoring of the global water and energy cycles, including water availability and ecosystem responses and feedbacks to climate change and human impacts. WIREs Water 2016, 3:834–853. doi: 10.1002/wat2.1168 For further resources related to this article, please visit the WIREs website.
Mohamed Elhag - One of the best experts on this subject based on the ideXlab platform.
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Forecasting of Remotely Sensed Daily Evapotranspiration Data Over Nile Delta Region, Egypt
Water Resources Management, 2013Co-Authors: Aris Psilovikos, Mohamed ElhagAbstract:Daily Evapotranspiration is a major component in crops water consumption management plans. Consequently, forecasting of daily Evapotranspiration is the keystone of any effective water resources management plans in fragile environment similar to the Nile Delta region. The estimation of daily Evapotranspiration was carried out using Surface Energy Balance System (SEBS), while the forecasting of the daily Evapotranspiration was carried out using Auto Regressive Integrated Moving Average (ARIMA) and its derivative Seasonal ARIMA. Remote sensing data were downloaded from European Space Agency (ESA) and used to estimate daily Evapotranspiration values. Remote sensing data collected from August 2005 till December 2009 on a monthly basis for daily Evapotranspiration estimation. The application of the most adequate ARIMA (2,1,2) to the Evapotranspiration data set failed to sustain the forecasting accuracy over a long period of time. Although, time series analysis of daily Evapotranspiration data set showed a seasonality behavior and thus, using seasonal ARIMA [(2,1,2) (1,1,2)6] was the optimum to forecast the daily Evapotranspiration over the study area and sustain the forecasting accuracy. A linear regression model was established to test the correlation between the forecasted daily Evapotranspiration values using S-ARIMA model and the actual values. The forecasting model indicates an increase of the daily Evapotranspiration values with about 1.3 mm per day.
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Application of the Sebs Water Balance Model in Estimating Daily Evapotranspiration and Evaporative Fraction from Remote Sensing Data Over the Nile Delta
Water Resources Management, 2011Co-Authors: Mohamed Elhag, Aris Psilovikos, Ioannis Manakos, Kostas PerakisAbstract:Estimation of Evapotranspiration is always a major component in water resources management. The reliable estimation of daily Evapotranspiration supports decision makers to review the current land use practices in terms of water management, while enabling them to propose proper land use changes. Traditional techniques of calculating daily Evapotranspiration based on field measurements are valid only for local scales. Earth observation satellite sensors are used in conjunction with Surface Energy Balance (SEB) models to overcome difficulties in obtaining daily Evapotranspiration measurements on a regional scale. In this study the SEB System (SEBS) is used to estimate daily Evapotranspiration and evaporative fraction over the Nile Delta along with data acquired by the Advance Along Track Scanning Radiometer (AATSR) and the Medium Spectral Resolution Imaging Spectrometer (MERIS), and six in situ meteorological stations. The simulated daily Evapotranspiration values are compared against actual ground-truth data taken from 92 points uniformly distributed all over the study area. The derived maps and the following correlation analysis show strong agreement, demonstrating SEBS’ applicability and accuracy in the estimation of daily Evapotranspiration over agricultural areas.
Youngryel Ryu - One of the best experts on this subject based on the ideXlab platform.
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on the temporal upscaling of Evapotranspiration from instantaneous remote sensing measurements to 8 day mean daily sums
Agricultural and Forest Meteorology, 2012Co-Authors: Youngryel Ryu, Dennis D Baldocchi, Beverly E Law, Andrew T Black, Matteo Detto, R Leuning, Akira Miyata, Markus Reichstein, Rodrigo VargasAbstract:a b s t r a c t The regular monitoring of Evapotranspiration from satellites has been limited because of discontinu- ous temporal coverage, resulting in snapshots at a particular point in space and time. We developed a temporal upscaling scheme using satellite-derived instantaneous estimates of Evapotranspiration to produce a daily-sum Evapotranspiration averaged over an 8-day interval. We tested this scheme against measured Evapotranspiration data from 34 eddy covariance flux towers covering seven plant functional types from boreal to tropical climatic zones. We found that the ratio of a half-hourly-sum of potential solar radiation (extraterrestrial solar irradiance on a plane parallel to the Earth's surface) between 10:00 hh and 14:00 hh to a daily-sum of potential solar radiation provides a robust scaling factor to convert a half-hourly measured Evapotranspiration to an estimate of a daily-sum; the estimated and measured daily sum Evapotranspiration showed strong linear relation (r 2 = 0.92) and small bias (−2.7%). By com- parison, assuming a constant evaporative fraction (the ratio of Evapotranspiration to available energy) during the daytime, although commonly used for temporal upscaling, caused 13% underestimation of Evapotranspiration on an annual scale. The proposed temporal upscaling scheme requires only latitude, longitude and time as input. Thus it will be useful for developing continuous Evapotranspiration estimates in space and time, which will improve continuous monitoring of hydrological cycle from local to global scales.
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integration of modis land and atmosphere products with a coupled process model to estimate gross primary productivity and Evapotranspiration from 1 km to global scales
Global Biogeochemical Cycles, 2011Co-Authors: Youngryel Ryu, Dennis D Baldocchi, Hideki Kobayashi, Catharine Van Ingen, Andy T Black, Jason Beringer, Eva Van Gorsel, Alexander Knohl, Beverly E LawAbstract:linear relations with measurements of solar irradiance (r 2 = 0.95, relative bias: 8%), gross primary productivity (r 2 = 0.86, relative bias: 5%) and Evapotranspiration (r 2 = 0.86, relative bias: 15%) in data from 33 flux towers that cover seven plant functional types across arctic to tropical climatic zones. A sensitivity analysis revealed that the gross primary productivity and Evapotranspiration computed in BESS were most sensitive to leaf area index and solar irradiance, respectively. We quantified the mean global terrestrial estimates of gross primary productivity and evapotranpiration between 2001 and 2003 as 118 � 26 PgC yr � 1 and 500 � 104 mm yr � 1 (equivalent to 63,000 � 13,100 km 3 yr � 1 ), respectively. BESS-derived gross primary productivity and Evapotranspiration estimates were consistent with the estimates from independent machine-learning, data-driven products, but the process-oriented structure has the advantage of diagnosing sensitivity of mechanisms. The process-based BESS is able to offer gridded biophysical variables everywhere from local to the total global land scales with an 8-day interval over multiple years.
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Integration of MODIS land and atmosphere products with a coupled-process model to estimate gross primary productivity and Evapotranspiration from 1 km to global scales
Global Biogeochemical Cycles, 2011Co-Authors: Youngryel Ryu, Dennis D Baldocchi, Hideki Kobayashi, Catharine Van Ingen, Jason Beringer, Eva Van Gorsel, Alexander Knohl, Beverly E Law, T. Andy Black, Olivier RoupsardAbstract:We propose the Breathing Earth System Simulator (BESS), an upscaling approach to quantify global gross primary productivity and Evapotranspiration using MODIS with a spatial resolution of 1-5 km and a temporal resolution of 8 days. This effort is novel because it is the first system that harmonizes and utilizes MODIS Atmosphere and Land products on the same projection and spatial resolution over the global land. This enabled us to use the MODIS Atmosphere products to calculate atmospheric radiative transfer for visual and near infrared radiation wave bands. Then we coupled atmospheric and canopy radiative transfer processes, with models that computed leaf photosynthesis, stomatal conductance and transpiration on the sunlit and shaded portions of the vegetation and soil. At the annual time step, the mass and energy fluxes derived from BESS showed strong linear relations with measurements of solar irradiance (r(2) = 0.95, relative bias: 8%), gross primary productivity (r(2) = 0.86, relative bias: 5%) and Evapotranspiration (r(2) = 0.86, relative bias: 15%) in data from 33 flux towers that cover seven plant functional types across arctic to tropical climatic zones. A sensitivity analysis revealed that the gross primary productivity and Evapotranspiration computed in BESS were most sensitive to leaf area index and solar irradiance, respectively. We quantified the mean global terrestrial estimates of gross primary productivity and evapotranpiration between 2001 and 2003 as 118 +/- 26 PgC yr(-1) and 500 +/- 104 mm yr(-1) (equivalent to 63,000 +/- 13,100 km(3) yr(-1)), respectively. BESS-derived gross primary productivity and Evapotranspiration estimates were consistent with the estimates from independent machine-learning, data-driven products, but the process-oriented structure has the advantage of diagnosing sensitivity of mechanisms. The process-based BESS is able to offer gridded biophysical variables everywhere from local to the total global land scales with an 8-day interval over multiple years.
