improved road weather forecasting by using high resolution satellite data claus petersen and bent h....
TRANSCRIPT
Improved road weather forecasting by using high resolution satellite data
Claus Petersen and Bent H. SassDanish Meteorological Institute
Background
• It has been realized that prediction of cloud cover and precipitation play a key role in prediction of the road surface temperature and the road conditions.
• Prediction of cloud cover requires a NWP model which can model clouds and data-assimilation of cloud cover and precipitation observations.
Viking project
• Title– Development of new generation of cloud and
precipitation analyses for the automatic Road Weather Model
• Duration– 2003-2005
• Goal– Improvement of the forecasts for slippery roads
by developing a new prediction model
Numerical Weather Prediction (NWP) model
Horizontal resolution
0.15x0.15 (degree)
Vertical levels 40
Rotation of south pole
Lon.=80 Lat.=0 (degree)
Number of grid points
610x568=346480
Dynamic time step
360 (s)
Physical time step
360 (s)
Boundary update Every 3rd hour
Boundary age 0-6 hours
First guess age 3 or 6 hours
Forecast frequency
Every 4th hour
Forecast length 60 hours
Data-assimilation 4 times daily+2 reassimilation cycles
Already used observations
Model domain of NWP model and network of road stations
•Horizontal resolution 0.15x0.15•Vertical levels 40•Number of grid points 82x98=8036 •Dynamic time step 72 s.•Physical time step 360 s.•Boundary update 1 hour
•Boundary age 0-5 hours•First guess age 0-1 hour•Forecast frequency Every hour•Forecast length 5-24 hours•Data-assimilation period 3 hours•Road stations 300
Data sources
Single channels or composite
Cloud mask Cloud top temperature
Precipitation intensity Cloud type
Application of cloud observations
Application of cloud observations
FORECAST
1 hour forecast of cloud mask
1 hour forecast of precipitation, mslp1 hour forecast of wind and temperature
Observed cloud mask
1 hour forecast with data-assimilation of satellite data
FORECAST
1 hour forecast of cloud mask
1 hour forecast of precipitation, mslp1 hour forecast of wind and temperature
Observed cloud mask
1 hour forecast without data-assimilation of satellite data
6 hour forecast of cloud mask
6 hour forecast of precipitation, mslp6 hour forecast of wind and temperature
Observed cloud mask
6 hour forecast with data-assimilation of satellite data
6 hour forecast of cloud mask
6 hour forecast of precipitation, mslp6 hour forecast of wind and temperature
Observed cloud mask
6 hour forecast without data-assimilation of satellite data
21 hour forecast of cloud mask
21 hour forecast of precipitation, mslp21 hour forecast of wind and temperature
Observed cloud mask
21 hour forecast with data-assimilation of satellite data
21 hour forecast of cloud mask
21 hour forecast of precipitation, mslp21 hour forecast of wind and temperature
Observed cloud mask
21 hour forecast without data-assimilation of satellite data
Road Condition Model
G: Ground heat fluxS: Direct insolationD: Diffuse insolationR: Infrared radiationH: Sensible heat fluxL: Latent heat fluxF: Flux correction
User interface
Verification of cloud forecast
•First two weeks of March 2005•Danish SYNOP stations•Limited MSG1 data•Verifcation for model run every hour
Best practice
• A general method has been developed to assimilate cloud observations into a NWP model.
• Verification and case studies indicate that prediction of cloud cover is improved for short range forecasting but that results can be further improved with more experience.
• Further verification and investigation of the road surface temperature dependency of cloud cover are needed.
• Satellite data will be used in the road weather model from this season
• The potential use of satellite data in other road application is very large.
QUESTIONS
CONTACTClaus Petersen [email protected]
Danish Meteorological InstituteLINKS
www.dmi.dkwww.eumetsat.int
http://nwcsaf.inm.es