Guangxi Zhiwu (May 2023)
Characteristics and influencing factors of water and heat fluxes over an vineyard in arid desert oasis region in the Northwest China
Abstract
To improve our understanding of farmland surface process and agricultural water management in arid oasis area, we analyzed the characteristics of water and heat fluxes at different time scales, and the influence of arid advection and canopy conductance (Gc) on water and heat fluxes at different growth stages. In addition, we used path analysis to study the influence path of environmental factors on latent heat flux (LE). In this paper, the water and heat fluxes were measured by eddy-covariance in 2017. The results were as follows: (1) LE showed multiple peaks, while the other fluxes were basically unimodal shapes at the daily scale. On the whole, the values of daily net radiation (Rn) were maximum, followed by LE, sensible heat flux (H) and soil heat flux (G) at each growth stage. The variation of diurnal G showed obvious lagged effect compared to that of Rn. (2) LE and H accounted for 86% and 14% (respectively) of daytime energy during the whole growing stages, indicating that LE was the main energy consumption item. The contribution of arid advection to daytime LE ranged from 5% to 59% with an average value of 28% at whole growing season. The influence of Gc on LE was stronger at the new shoot and leaf-fall stages than that in the middle growing season. (3) LE was mainly affected by Rn, followed by vapor pressure deficit (VPD) and air temperature (Ta), and the influence degrees of VPD and Ta on LE were similar. Furthermore, the path analysis showed that Rn directly affected LE; VPD and Ta mainly affected LE indirectly through Rn. As a whole, the water and heat fluxes in vineyards of arid desert oasis in Northwest China display significant diurnal and seasonal variations, and the influences of environmental factors on these exists great discrepancies in magnitude and path.
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