Recent advances in remote sensing of evapotranspiration

Authors: BHATTARAI, NISHAN - University Of Michigan; Wagle, Pradeep

Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2021
Publication Date: 8/23/2021
Citation: Bhattarai, N., Wagle, P. 2021. Recent advances in remote sensing of evapotranspiration. Remote Sensing. 13(21). Article 4260

Interpretive Summary: Evapotranspiration (ET) is a critical component of the water and energy balances. The number of remote sensing-based ET products and estimation methods has increased in recent decades. However, quantifying and mapping the spatiotemporal distribution of ET across a large area is still a challenge due to limited applicability of remote sensing-based ET tools under all conditions, scarcity of calibration and validation datasets, and spectral and spatiotemporal constraints of available satellite sensors. Various aspects of ET modeling approaches and their applications are reported in the 13 papers published in this special issue. Contributions included development of novel models to improvement of existing ones, and a broad range of applications from estimating vegetation water use to assessing vegetation health and drought impacts. Additionally, integrations of multiple sensors or multi-sensor image fusion approaches were also highlighted by some studies to address limitations associated with spatiotemporal capabilities of the currently available satellite sensors. The topics covered in this special issue provide valuable insights into the development, improvement, and applications of remote-sensing-based ET models and products to support efforts to sustainably manage water resources under a changing climate.

Technical Abstract: Evapotranspiration (ET) plays an important role in coupling the global energy, water, and biogeochemical cycles. As one of the key ecohydrological processes within the Earth’s system, ET can explain ecosystem responses to global environmental change. However, quantifying and mapping the spatiotemporal distribution of ET across a large area is still a challenge, which limits our understanding of how a given ecosystem function under a changing climate. This also poses a challenge to water managers, farmers, and ranchers who often rely on accurate estimates of ET to make important irrigation and management decisions. Over the last three decades, remote sensing-based ET modeling tools have played a significant role in managing water resources and understanding the land-atmosphere interactions. However, several challenges, including limited applicability under all conditions, scarcity of calibration and validation datasets, and spectral and spatiotemporal constraints of available satellite sensors, exist in the current state-of-the-art remote sensing-based ET models and products. The special issue on “Remote Sensing of Evapotranspiration II” was launched to attract studies focusing on recent advances in remote sensing-based ET models to help address some of these challenges and find novel ways of applying and/or integrating remotely sensed ET products with other datasets to answer key questions related to water and environmental sustainability. The 13 articles published in this special issue cover a wide range of topics ranging from field to global-scale analysis, individual model to multi-model evaluation, single sensor to multi-sensor fusion, and highlight recent advances and applications of remote sensing-based ET modeling tools and products.