Impact of different within-canopy wind attenuation formulations on modelling evapotranspiration using TSEBm

Authors: NIETO, H. - Institute De Recerca I Tecnologia Agroalimentaries (IRTA); Kustas, William - Bill; Alfieri, Joseph; FENG, MIN - University Of Maryland; HIPPS, L.E. - Utah State University; LOS, S. - Utah State University; Prueger, John; McKee, Lynn; Anderson, Martha

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2018
Publication Date: 11/22/2018
Citation: Nieto, H., Kustas, W.P., Alfieri, J.G., Feng, M., Hipps, L., Los, S., Prueger, J.H., McKee, L.G., Anderson, M.C. 2018. Impact of different within-canopy wind attenuation formulations on modelling evapotranspiration using TSEBm. Irrigation Science. https://doi.org/10.1007/s00271-018-0611-y.
DOI: https://doi.org/10.1007/s00271-018-0611-y

Interpretive Summary: The unique vertical canopy structure and the strongly clumped plant distribution/row structure of vineyards and orchards creates an environment that is likely to cause the wind profile inside the canopy air space to deviate from how it is typically modeled for most crops. This, in turn, affects the efficiency of heat and water loss from the soil and plants. This study evaluates the impact of using a new wind profile formulation in the canopy air space that explicitly considers the unique vertical variation in plant biomass of vineyards. The new wind profile is implemented into the remote sensing-based Two-Source Energy Balance (TSEB) model. Results indicate the new wind profile model better captures within-canopy winds during the spring when there coexist two vegetation layers resulting in improved TSEB model output. This work is important for developing a robust remote sensing-based energy balance modeling system for monitoring vineyard water use and plant stress over the growing season that can be applied using satellite and airborne imagery for field to regional scale applications. These tools are crucially needed in intensive agricultural production regions with arid and semi-arid climates such as the Central Valley of California, which experiences significant and prolonged droughts causing major water shortages and issues with water allocation for irrigated agriculture.

Technical Abstract: The unique vertical canopy structure and the strongly clumped plant distribution/row structure of vineyards and orchards creates an environment that is likely to cause the wind profile inside the canopy air space to deviate from how it is typically modeled for most crops. This in turn affects the efficiency of flux exchange and energy transport as well as the partitioning between the plant canopy and soil/substrate layers. This study evaluates the impact of using a new wind profile formulation in the canopy air space that explicitly considers the unique vertical variation in plant biomass of vineyards. The impact of the new wind profile formulation is evaluated with measurements of wind speed in a vineyard interrow, as well as with its implementation into the two-source energy balance (TSEB) model, which uses land surface temperature as the key boundary condition for flux estimation. This is very relevant in developing a robust remote sensing-based energy balance modeling system for monitoring vineyard water use or evapotranspiration (ET) that can be applied using satellite and airborne imagery for field to regional scale applications. These tools are crucially needed in intensive agricultural production regions with arid and semi-arid climates such as the Central Valley of California, which experiences significant and prolonged droughts causing major water shortages and issues with water allocation for irrigated agriculture.