Developing an Integrated Complementary Relationship for Estimating Evapotranspiration
| Autor: | Jagath J. Kaluarachchi, Homin Kim |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
010504 meteorology & atmospheric sciences
Mean squared error 0208 environmental biotechnology Eddy covariance Magnitude (mathematics) 02 engineering and technology Function (mathematics) Atmospheric sciences 01 natural sciences Normalized Difference Vegetation Index 020801 environmental engineering Surface energy balance Evapotranspiration Precipitation 0105 earth and related environmental sciences Mathematics |
| Zdroj: | Natural Resources. :89-109 |
| ISSN: | 2158-7086 2158-706X |
| DOI: | 10.4236/nr.2018.94007 |
| Popis: | The complementary relationship for estimating evapotranspiration (ET) is a simple approach requiring only commonly available meteorological data; however, most complementary relationship models decrease in predictive power with increasing aridity. In this study, a previously developed Granger and Gray (GG) model by using Budyko framework is further improved to estimate ET under a variety of climatic conditions. This updated GG model, GG-NDVI, includes Normalized Difference Vegetation Index (NDVI), precipitation, and potential evapotranspiration based on the Budyko framework. The Budyko framework is consistent with the complementary relationship and performs well under dry conditions. We validated the GG-NDVI model under operational conditions with the commonly used remote sensing-based Operational Simplified Surface Energy Balance (SSEBop) model at 60 Eddy Covariance AmeriFlux sites located in the USA. Results showed that the Root Mean Square Error (RMSE) for GG-NDVI ranged between 15 and 20 mm/month, which is lower than for SSEBop every year. Although the magnitude of agreement seems to vary from site to site and from season to season, the occurrences of RMSE less than 20 mm/month with the proposed model are more frequent than with SSEBop in both dry and wet sites. Another finding is that the assumption of symmetric complementary relationship is a deficiency in GG-NDVI that may introduce an inherent limitation under certain conditions. We proposed a nonlinear correction function that was incorporated into GG-NDVI to overcome this limitation. As a result, the proposed model produced much lower RMSE values, along with lower RMSE across more sites, as compared to SSEBop. |
| Databáze: | OpenAIRE |
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