Fourth Study Conference on BALTEX Scala Cinema Gudhjem

To study land-surface atmosphere interaction processes
under heterogeneous terrain conditions is one of the major
research activities of the MOL. In addition to the operational
boundary layer measurement program at the GM
Falkenberg, micrometeorological measurements have been
performed both at a forest and at a lake site during the last 4
years. Moreover, major field experiments have been
organised in 1998 (Beyrich et al., 2002) and in 2003
(Beyrich et al., this volume) for detailed studies of land
surface and boundary layer processes.
The terrain heterogeneity is a fact the user of the CEOP data
from Lindenberg should be aware of when performing
validation studies against model output or satellite data. It is
obvious, that the two major land use classes - forest and
agricultural farmland - behave different with respect to
surface - atmosphere exchange processes. This is illustrated
in Figures 2 showing the averaged diurnal cycle of the mean
(2 m) air temperature, net radiation and sensible heat fluxes
during two months of CEOP EOP1 and EOP3, respectively.
Mean air temperature may differ by about 1 K which is
mainly due to the topography. Differences in net radiation
during daytime amount up to about 25 %, and the
differences in the sensible heat flux are even more
pronounced (up to about a factor of 2 or 100 %).
Temperature in deg C
Net radiation in W/m 2
Sensible heat flux in W/m 2
26
24
22
20
18
16
14
12
T, July 2001
Grassland
Forest
10
00:00 03:00 06:00 09:00 12:00
UTC
15:00 18:00 21:00 00:00
600
500
400
300
200
100
0
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
-100
250
200
150
100
50
-50
Rn, July 2001
H, July 2001
UTC
Grassland
Forest
0
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
UTC
Grassland
Forest
Figure 2. Mean diurnal cycle of air temperature, net
radiation and sensible heat flux during July, 2001 and
February, 2003 at GM Falkenberg (farmland) and at
the Kehrigk forest site (pine forest, 12 km West of
Falkenberg)
- 72 -
The Lindenberg data for CEOP available via the CDA so
far include the near surface measurements carried out at
GM Falkenberg, representing the farmland part of the
area, and hence only half of the truth. When comparing
model output against our measurements, the user should
be aware of what type of land use his model assumes for
the Lindenberg grid cell. This may be highly dependent on
grid size, actual position of the grid cell, and on the
scheme applied to describe land surface characteristics
(dominant land use, tile / mosaic approach etc.). Data from
the forest site (representing the second half of the truth)
may be made available upon request.
References
Beyrich, F., H.-J. Herzog, J. Neisser: The LITFASS
project of DWD and the LITFASS-98 experiment: The
project strategy and the experimental setup. Theor.
Appl. Climatol. 73, 3-18, 2002
Neisser, J., W. Adam, F. Beyrich, U. Leiterer, H.
Steinhagen: Atmospheric boundary layer monitoring
at the Meteorological Observatory Lindenberg as a
part of the "Lindenberg Column": Facilities and
selected results. Meteorol. Z. (N.F.) 11, 241-253, 2002
Temperature in deg C
Net radiation in W/m 2
Sensible heat flux in W/m 2
2
1
0
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
-1
-2
-3
-4
-5
-6
250
200
150
100
50
-50
-100
T, February 2003
Rn, February 2003
UTC
Grassland
Forest
0
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
100
80
60
40
20
-20
-40
H, February 2003
UTC
Grassland
Forest
0
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00
UTC
Grassland
Forest