Evaluation of soil resistance formulations for estimates of sensible heat flux in a desert vineyard

Authors: LI, Y. - Chinese Academy Of Sciences; Kustas, William - Bill; HUANG, C. - Chinese Academy Of Sciences; KOOL, D. - Iowa State University; HAGHIGHI, E. - Massachusetts Institute Of Technology

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2018
Publication Date: 7/18/2018
Citation: Li, Y., Kustas, W.P., Huang, C., Kool, D., Haghighi, E. 2018. Evaluation of soil resistance formulations for estimates of sensible heat flux in a desert vineyard. Agricultural and Forest Meteorology. https://doi.org/10.1O6/j.agrformet.2018.06.019.
DOI: https://doi.org/10.1 Ol 6/j.agrformet.2018.06.019

Interpretive Summary: For irrigated vineyards, accurate estimates of the partitioning of evapotranspiration into soil evaporation and vine transpiration is important for evaluating vine water use and stress. The Two-Source Energy Balance (TSEB) model estimates soil evaporation and plant transpiration using remotely-sensed land surface temperature which can be applied with satellite data over large areas. However, when the TSEB model was applied over a drip-irrigated vineyard in the arid central Negev Highlands of Israel, the current soil resistance formulation for estimating soil evaporation required calibration to obtain reasonable agreement with soil evaporation measurements. A recently proposed alternative soil resistance formulation was also applied and evaluated for estimating the soil evaporation. The results show that the newly proposed soil resistance formulation performs as well as the current, locally-calibrated soil resistance formulation in TSEB without the need for calibration. This suggests that using the new soil resistance formulation is likely to provide more reliable partitioning of evapotranspiration into soil evaporation and vine transpiration important for assessing vine water use and stress, which significantly impacts grape quality and yield.

Technical Abstract: For irrigated vineyards, accurate estimates of the sensible heat flux from the soil surface (HS) is essential for determining the contribution of soil evaporation (E) to evapotranspiration (ET) using thermal-based energy balance approaches. A key to accurate estimates of HS is having a robust physically-based soil resistance formulation. In this study a comparison is conducted between a soil resistance algorithm derived from field and laboratory studies that has been successfully used in the thermal-based Two-Source Energy Balance (TSEB) model to estimate the surface energy balance over a wide variety of fractional vegetation cover and soil moisture conditions, and a soil resistance formulation recently proposed based on near-surface transport theory for a drying surface layer with clumped roughness elements/vegetation validated from laboratory experiments. Both soil resistance algorithms were applied and evaluated over a drip-irrigated vineyard in the arid central Negev Highlands of Israel. The sensible heat flux from soil surface below the vine and in the midrow were compared with estimates from a previous study using in-situ observations of soil surface available energy, soil evaporation and radiometric temperatures. The results show that the newly proposed soil resistance formulation performs well while the commonly used soil resistance formulation in TSEB without calibration results in overestimation of HS in vineyards.