(more details francis.pouponneau++at++meteo.fr)
The scores (bias and root mean squared error) plotted on the next figure correspond to the scores calculated against surface observations SYNOP over the domain ALADIN-FRANCE. Scores are averaged over the three months of the third quarter 1999, for each 6 hours time step.
We use about 200 synoptic stations over the domain.
The RMS rises with time step from 0.6 to 1.8 hPa. For the bias there are two phenomena :
Bias shows an overestimation on afternoon (forecast range 12 and 36 hours) and an underestimation at night and morning. The RMS is about 2° with a diurnal cycle amplitude about 1°.
There is a diurnal cycle of the error of the rms (amplitude about 8%) and an underestimation of humidity.
Next table are the cloud cover and precipitation contingency table for the 36 hours forecast range of ALADIN-FRANCE. Classes are used the verification of NWP models in EUROPE (EWGLAM).
The percent of correct is 50%. The high nebulosity class (7-8) is more observed than forecasted : 34 against 17% . While clow and medium cloud cover classes are more forecasted than observed.
CLOUD COVER: 9907-9909 (83 days), MODEL: ALADIN, AREA: FRANP01-France, Range: 36 H
|
Obs/Forecast |
0 - 2 |
3 - 6 |
7 - 8 |
SUM | |
|---|---|---|---|---|---|
0 - 2 |
16.5% |
6.9% |
0.5% |
23.9% | |
3 - 6 |
12.1% |
23.4% |
6.2% |
41.7% | |
7 - 8 |
4.4% |
19.5% |
10.6% |
34.5% | |
SUM |
33.0% |
49.8% |
17.2% |
20054 obs | |
Correct: 50.4% |
Rousseau: 0.23 |
Heidke: 0.24 |
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The percent of correct is almost 74%. "Light precipitation" class have been more forecasted than observed, nearly two times more. It is the opposite for "no rain" class : 73 again 82%. Climatology of heavy and moderate rain is quite good.
PRECIPITATIONS: 9907-9909 (83 days), MODEL: ALADIN, AREA: FRANP01-France, Range: 36 H
Obs/Forecast |
NO rain |
LIGHT |
MODERATE |
HEAVY |
SUM |
|---|---|---|---|---|---|
NO rain |
66.8% |
12.6% |
2.2% |
0.3% |
81.9% |
LIGHT |
4.2% |
4.5% |
1.7% |
0.2% |
10.6% |
MODERATE |
1.3% |
2.7% |
1.9% |
0.3% |
6.2% |
HEAVY |
0.2% |
0.4% |
0.4% |
0.2% |
1.3% |
SUM |
72.6% |
20.2% |
6.2% |
1.0% |
21043 obs |
Correct: 73.5% |
Rousseau: 0.29 |
Heidke: 0.30 | |||
Bias shows an underestimation for the 700 hPa level and an overestimation above 700 hPa. RMS increases from 700 hPa to 200 hPa, decreases over 200 hPa.
The temperature is overestimated in the troposphere and underested in highter levels. RMS is maximum low level and at the tropopause and varies from 1.2 to 2°.
The bias shows an overestimation except in first low layers. The RMS increases up to 300 hPa.
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