AR01 Histogram
AR02 Histogram
Road Radiometric
600
600
500
500
Temperatures
400
400
Temperature and Humidity-Ames RWIS site
300
300
200
200
Solar Flux-Ames garage.
100
100
0
0
Solar Flux values on the hour
Temperature Bin
Temperature Bin
Hourly averaged solar flux value
centered on the hour
Infrared Flux computed from cloud
information
AR03 Histogram
MDSS forecast
700
AR04 Histogram
600
800
Observed at Ames Municipal Airport
700
500
600
400
500
Precipitation rate Ames Municipal Airport
300
400
300
200
200
100
100
0
0
Temperature Bin
Temperature Bin
Fig. 12.3. Infrared imagery for 03/17/2004 on I-35N near the Ames DOT garage. The
histograms of the radiometric temperatures obtained from the analysis of the IR imagery
for the four AOIs are also presented.
For 18 UTC we had three values: the zero- hour ensemble forecast model meteorological
conditions from the present forecast plus the information from the two previous 18 UTC
ensemble forecasts. We used all information and plotted the maximum and minimum
predicted road surface temperature. Fig. 12.4 presents the predicted road surface
temperatures based on the average solar flux, the observed meteorological conditions,
and the IR flux computed from the ensemble forecast cloud conditions plus the minimum
and maximum road surface temperatures predicted using the ensemble forecast
meteorological information. For the observed meteorological conditions (using the
forecast cloud amounts) the first SNTHERM-RT prediction was Day Of the Year (DOY)
73 at 18:00L. For approximately the first 4-6 hours the model `spins up' and the predicted
values are less than the observed road surface temperatures. The areas blocked in yellow
are periods when SNTHERM-RT model runs based on the observed meteorological
conditions predicts snow on the road surface. Temperature comparisons should not be
made during these periods since the snow was not artificially removed to correspond to
removal of snow by plowing or the application of chemicals or salt and sand. In the
SNTHERM-RT model runs using the ensemble forecast meteorological conditions the
snow was artificially removed when the Ames garage reported plowing or the application
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