Field-scale intercomparison analysis of ecosystems in partitioning surface energy balance components in a semi-arid environment

摘要

In situ land surface flux monitoring studies can be useful to extrapolate canopy scales processes to weather and climate analysis. This paper evaluated the interaction between ecosystems and environmental forces in partitioning available energy from multi-sensor platform in the semi-arid region of the Snake River basin in Idaho, USA. Field measurements of latent and sensible heat fluxes using scintillometers and the eddy covariance flux data during the growing season in 2011-2012 were able to identify spatial and seasonal variability in partitioning of surface energy components, including net radiation, latent, sensible, ground heat fluxes. Available energy measured from sagebrush, cheatgrass and lodgepole pine ecosystems indicate that 79%, 58%, and 62% partitioned into latent heat fluxes of 24%, 20%, and 35%, respectively. Role of precipitation and soil moisture, which in turn influenced the latent and sensible heat flux more profoundly were evident in sagebrush and cheatgrass as compared to lodgepole pine with a higher vapor pressure deficit and decreased relative humidity especially in the summertime between June and September. The Budyko analysis revealed that aridity index ratio was found to vary between 3 and 5 suggesting a degree of aridity in these ecosystems. Evapotranspiration (ET) was severely constrained by lack of soil moisture for cheatgrass and sagebrush when compared to the lodgepole pine ecosystem. In addition, it has been concluded that the sagebrush ecosystem regions can serve as recharge zones for enhancing groundwater storage in the Snake River Plains as they exhibit lower evapotranspiration rates in comparison to other ecosystems. This study emphasizes that use of field data can provide a better understanding of boundary layer fluxes, which in turn can help validate the fluxes simulated by land surface models. Implications of these results include the need for sustained monitoring and land-atmosphere interaction studies that are beneficial for effective water resource assessment and management. (C) 2018 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.