Comparison of sensible heat fluxes by large aperture scintillometry and eddy covariance over two contrasting−climate vineyards

Abstract

Measurements of turbulent energy fluxes between land surface and the atmosphere are commonly carried out applying the eddy covariance (EC) method. Nevertheless, in some cases (e.g. surface heterogeneity, remote sensing or model validation), the use of a Large Aperture Scintillometer (LAS) is more appropriate. We compared LAS and EC measurements of sensible heat flux (H) over two contrasting vineyards of Southern (MIN site) and Northern (LIS site) Italy, mainly differentiating for climate (i.e. dry and humid), water management (i.e. irrigated and rainfed), and LAS setup. The relationship between H by LAS (HLAS) and by EC (HEC) was good at both sites, but with slightly higher HLAS. At MIN, where multiple EC stations were deployed, the best agreement was found with the station in the center of LAS path. Surface heterogeneity due to irrigation had different impact on HLAS depending on location of the source area. The canopy growth at LIS during the study period caused the approaching of LAS beam to the roughness sublayer, resulting in a reduction of HLAS compared to HEC. The closure of energy balance was higher (79%) at MIN and lower (64%) at LIS, but the agreement between HLAS and HEC was similar at both sites, suggesting that particular attention should be given to latent heat flux measurements by EC in order to better understand the energy balance closure issue.