Observations of the Temperature and Humidity Structure Parameter Over Heterogeneous Terrain by Airborne Measurements During the LITFASS-2003 Campaign

摘要

The turbulent structure parameters of temperature (C-T(2)) and humidity (C-Q(2)), and their cross-structure parameter (C-QT), are investigated using data collected with the airborne-measurement platform Helipod during the LITFASS-2003 campaign. The flights took place within the atmospheric surface layer over heterogeneous terrain including forests, a lake and farmland. We find variability in C-T(2) along such flight legs, with values of C-T(2) over forested surfaces one order of magnitude larger than over farmland, and two orders of magnitude larger than over the lake. However, a quantitative relationship between the magnitude of C-Q(2) and the surface type is not found, most likely due to a similar surface latent heat flux between the land-use types. However, when the different flight legs are taken together and data grouped by land-use type, values of C-Q(2) are significantly lower over the lake than over the other surfaces. A classification of C-QT is only possible between water and land surfaces, with lower values over water. We find the correlation coefficient R-QT in the range of 0.4-1.0, which is less than unity, and thus violates the assumption of unity in Monin-Obukhov similarity theory.