Fourth Study Conference on BALTEX Scala Cinema Gudhjem

Figure 4. The flight pattern Vertical Grid.
3. Results
Fig. 5 shows the profile of the latent heat flux from Helipod
Vertical Grid flights and measurements of a DIfferential
Absorption Lidar (DIAL). The fluxes agree well at all
altitudes.
Figure 5. Comparison Helipod and DIAL measurements.
From Helipod’s ‘Catalog’ flight pattern the sensible heat
fluxes above different surface types were calculated (Fig. 6).
At the lowest flight level the various surface types
(grassland, agriculture, lake, forest, and the mix) caused
significant differences in the fluxes. This effect decreased
with altitude. Since each surface type seemed to have its
own linear flux profile it may be thought about how mixed
the mixed layer really was?
The Fig. 7 shows area-averaged turbulent fluxes that were
calculated from Helipod and research aircraft Do 128
measurements. The surface fluxes were determined using
two different methods: The conventional 3D-method and a
combination of low-level flights (Grunwald et al. 1998) with
inverse models (LLF+IM). The results were compared to
ground station and wind profiler/RASS data. The LLF+IM
method yield clearly better agreement with the ground-based
measurements than the usual 3D method.
-70-
Figure 6. Sensible heat flux above different surface
types
Figure 7. Area-average fluxes from different methods
(LLF+IM, 3D-method)
References
Bange J., and R. Roth: Helicopter-Borne Flux
Measurements in the Nocturnal Boundary Layer Over
Land – a Case <strong>Study</strong>. Boundary-Layer Meteorol., 92,
295-325, 1999
Bange, J., F. Beyrich, and D.A.M. Engelbart: Airborne
Measurements during LITFASS-98: A Case <strong>Study</strong>
about Method and Significance, Theor. Appl.
Climatol., 73, 35-51, 2002
Grunwald, J., N. Kalkhoff, F. Fiedler, and U. Corsmeier,:
Application of Different Flight Strategies to
Determine Areally Averaged Turbulent Fluxes. Beitr.
Phys. Atmosph., 71, 283-302, 1998
Zittel, P., T. Spiess, and J. Bange: Area-Average
Turbulent Fluxes from Airborne Measurements over
Heterogeneous Terrain using he Inverse Method and
MR Cospectra. EGS-EGU-EUG joint Assembly,
P1108, 2003