henning gisselø danish meteorological institute in copenhagen operational forecaster for 17 years
TRANSCRIPT
Henning Gisselø
• Danish Meteorological Institute in Copenhagen
• Operational forecaster for 17 years
S03 HIRLAM (NWP) has problems when predicting 2mTemp (max and min) in cases with no or just a few clouds.
S03 HIRLAM
• 3.3km * 3.3km * 40 layers * 90sek
• +54 h
• Hydrostatic
• Introduced spring 2009
In situations with only a few clouds
the model is predicting too low max temp in day time and too high min temp in night time.
CASE
The night between
the 13th and 14th October 2009
Analysis, 14th Oct. 00 UTC
NOAA, 14th Oct. 02:43 UTC
S03 2mT Min, wind, cloudcover
S03 2mT Min, wind, cloudcover
- 3
- 5
- 2 - 3
- 4
- 4
- 4
- 1
+ 3
Possible explainations from
The HIRLAM Developing Group
DAYTIMECLOUDCOVER
• MODEL: many clouds
• ACTUALLY: few clouds
• RESULT: higher temp observed than predicted by model
DAYTIMEEVAPORATION
• MODEL: high evaporation (moist soil)
• ACTUALLY: low evaporation (dry soil)
• RESULT: higher temp observed than predicted by model
NIGHT TIMECLOUDCOVER
• MODEL: many clouds
• ACTUALLY: few clouds
• RESULT: lower temp observed than predicted by model
NIGHT TIMEHEAT CONDUCTION FROM GROUND
• MODEL: high heat conduction from ground
• ACTUALLY: low heat conduction from ground
• RESULT: lower temp observed than predicted by model
NIGHT TIMEVEGETATION
• MODEL: low vegetation
• ACTUALLY: high vegetation
• High vegetation cools more efficient than low vegetation, producing a cooler surface layer.
• RESULT: lower temp observed than predicted by model
Growing through spring and summer
END OF STORY