Chemistry Reference
In-Depth Information
Fig. 10 (a-b) Weekday variation of the N
50
concentration in Central European background
(a, Melpitz, Germany) and in Northern European background (b, Hyyti
¨
l
¨
, Finland).
Dots
indicate
median concentrations (cm
3
) and the
bars
show the variation between 25th and 75th percentile.
The
p
values represent the possibility that all of the weekday distributions are from the same
distribution as a result of a U-test. The period of measurements in days is given as N. (c and d)
same for N
100
concentrations. Adapted from [
11
]
3.5 Comparing Measurements of Number Size Distribution
with Model Output
One of the main uses of comparable size distribution dataset is model-measurement
comparison. Without comparable data, the air quality and climate models do not
have a way to reliably validate their results. In model-to-measurement comparison,
many application-based conditions must be taken into account, and especially for
aerosol number size distribution, some of the key points are [
18
]:
• The comparison must be done with similar properties (STP conditions (
T
¼
293.15 K,
P
¼
101,300 Pa), dry aerosol).
• Similar timescales for comparison. Short-term simulations can provide easily
different or similar particle number size distributions than measured, just from
overall model internal variability.
