User's Guide to the Model Validation Kit - Harmonisation within ...

5.3 Lillestrøm data
5.3.1 Experimental set-up
The tracer experiments of concern here took place in the town of
Lillestrøm (near Oslo), Norway in 1987. They were performed by the
Norwegian Institute of Air Research (NILU) which has put the data at
our disposal.
A detailed description is given by Haugsbakk and Tønnesen (1989;
available on request). A shorter description is found in the paper by
Grønskei (1990).
Release from a 36 m mast.
15-minute sampling
The experiments were carried out in a flat residential area with 6-10
m high buildings and trees. A tracer system was used in which SF 6
was released from a mast 36 m above the ground. Each experiment
consisted of two sequential 15-min periods. Thus, the sampling
period is shorter than for the other experiments considered at the
workshop.
The meteorological measurements were carried out along the 36 m
high mast.
Sonic anemometer measurements were processed to give 10 min
average values for wind speed and wind directions at the 10 m level.
Further, covariances were determined between velocity components,
and between velocity components and temperature fluctuations.
Norwegian winter: Snowcovered
ground, low sun
The temperature during the tracer experiments was low ( - 20(
Celsius), and the ground was snow-covered. The sun was above the
horizon, but at a very low angle. The surface roughness was about 0.5
m.
Generally, the vertical temperature profiles in the lowest 100 m
showed an inversion (Haugsbakk and Tønnesen, 1989).
For all runs during the experimental campaign, the crosswind
profiles of tracer concentrations were well determined, thus making a
relatively accurate estimate of crosswind integrated concentration
possible. The maximum concentrations given in the data set is the
highest observed concentration along each arc.
Geographical coordinates for the position of release are: latitude
59.889 N, longitude 11.051 E; the height of terrain is 110 m a.m.s.l.
5.3.2 Points to be noted
Note that for Lillestrøm data, the averaging period is only 15 minutes
for the tracer data. Concentration averages taken over longer time
will tend to be smaller than those registered, due to meandering.
There was generally very light wind during the experiments.
u *
was recorded as zero for the experiment with the highest concentrations.
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