1. Weather Dependency of Quality Control Thresholds Mesoscale Atmospheric Network -project
Vesa Hasu

2. Thresholds in Quality Control
Thresholds in Quality Control
Quality control thresholds indicate when the measurement is suspicious or erroneous
Usually the quality control of meteorological measurement test either range (consistency) or step (change in given time window)
Thresholds are related into the latter type tests, i.e.
|x(t)-x(t-Δt)| < ΔxΔt  measurement ok,
|x(t)-x(t-Δt)| ≥ ΔxΔt  measurement suspicious,
where x is the measurement, t is time, Δt is the length of test time window, and ΔxΔt is the threshold
VH - Weather Dependency of Quality Control Thresholds

3. Thresholds in Quality Control
Thresholds in Quality Control
Threshold can be, for example:
Constants (QC1 in HTB)
Month-dependent constants (QC1 in HTB)
Adaptive (in the future?)
Adaptive to diurnal changes (in the future?)
However, we know that measurement changes depend on the weather, so:
Shouldn’t the quality control thresholds be also weather dependent?
VH - Weather Dependency of Quality Control Thresholds

4. Hunt for Weather Dependent Thresholds
Hunt for Weather Dependent Thresholds
The goal is to improve flagging thresholds of quality control
The main principle for this project assignment:
KISS – Keep It Simple, Stupid
Note: the problem is more engineering problem than a meteorological problem, therefore the approach is taken accordingly
The first approach: how much can rain explain the relatively large changes in the other measurements?
That is, is Δxrain different from Δxno rain?
VH - Weather Dependency of Quality Control Thresholds

5.
Harmaja in August 2005
Average wind 5 minute change* as a function of the mean rain intensity of two previous values
*Note: the average wind is taken over 10 minutes, and two successive values 5 minutes apart are compared
VH - Weather Dependency of Quality Control Thresholds

6.
The Plans
Initially, some rain-dependency can be seen especially in the wind measurements
More dates, stations, measurements, explaining variables must be examined before the final recommendations
VH - Weather Dependency of Quality Control Thresholds