Validation of a simple diagnostic relationship for downslope flows

Abstract

A simple conceptual view of downslope flows allows a derivation of a diagnostic relationship between the maximum depth of the flow, its speed, the slope angle and the cooling flux. This relationship is obtained considering that the turbulence cooling causing the air to flow downslope is essentially compensated by the warming by compression as the flow reaches higher pressure levels. The obtained relationship is consistent with the bulk heat budget for the along-slope flows, and its agreement with existing prognostic layeraveraged models is checked. Finally, the depth of the flow obtained from the diagnostic relationship is compared against the observational estimations of katabatic flows from two experimental campaigns. K E Y W O R D S diagnostic formula, downslope flow, katabatic depth, MATERHORN campaign, METCRAX II campaign

Vertical profiles of temperature, wind, and turbulent fluxes across a deciduous forest over a slope observed with a UAV

“…On the other hand, there is a significant positive temperature flux in the layer 10-15 m agl, a finding that needs further exploration. This feature could be either due to a too-short sampling time or to the presence of the lower layer of trees and the top of the downslope flow, a layer for which positive occurrences of the sensible heat flux have been reported in stably stratified layers (Cuxart et al, 2020).…”