Airborne Measurements of Scale-Dependent Latent Heat Flux Impacted by
Water Vapor and Vertical Velocity over Heterogeneous Land Surfaces
During the CHEESEHEAD19 Campaign
Abstract
The spatiotemporal variability of latent heat flux (LE) and water vapor
mixing ratio (rv) variability are not well understood due to the
scale-dependent and nonlinear atmospheric energy balance responses to
land surface heterogeneity. Airborne in situ and profiling Raman lidar
measurements with the wavelet technique are utilized to investigate
scale-dependent relationships among LE, vertical velocity (w) variance
(s2w), and rv variance (s2wv) over a heterogeneous surface in the
Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a
High-density Extensive Array of Detectors 2019 (CHEESEHEAD19) field
campaign. Our findings reveal distinct scale distributions of LE, s2w,
and s2wv at 100 m height, with a majority scale range of 120m-4km in LE,
32m-2km in s2w, and 200 m – 8 km in s2wv. The scales are classified
into three scale ranges, the turbulent scale (8m–200m), large-eddy
scale (200m–2km), and mesoscale (2 km–8km) to evaluate scale-resolved
LE contributed by s2w and s2wv. In the large-eddy scale in Planetary
Boundary Layer (PBL), 69-75% of total LE comes from 31-51% of the
total sw and 39-59% of the total s2wv. Variations exist in LE, s2w, and
s2wv, with a range of 1.7-11.1% of total values in monthly-mean
variation, and 0.6–7.8% of total values in flight legs from July to
September. These results confirm the dominant role of the large-eddy
scale in the PBL in the vertical moisture transport from the surface to
the PBL. This analysis complements published scale-dependent LE
variations, which lack detailed scale-dependent vertical velocity and
moisture information.