Verification of the ARPS and Verification of the ARPS and NAM Model Forecast Winds NAM Model Forecast Winds in the East Central Florida in the East Central Florida Coastal ZoneCoastal Zone
Arlena MosesArlena MosesDepartment of Marine and Environmental SystemsDepartment of Marine and Environmental SystemsFlorida Institute of TechnologyFlorida Institute of TechnologyMelbourne, FL 32901Melbourne, FL 32901
OverviewOverview
Introduction Analysis Methods Model Performance Performance During Tropical Storm Arlene Summary
Why are We Interested in Wind Why are We Interested in Wind Forecasts?Forecasts? Winds direction and speed can affect
Atmospheric stability Convective Development (or lack thereof) Commercial and Recreational Boating Interests Dispersion of smoke and toxic substances Rocket and Shuttle Launch Conditions
Inaccurate wind forecasts can cause feedback in other portions of the forecast
Why Choose These Models?Why Choose These Models?
Wet season weather is often dominated by local circulations
WFO Melbourne provides gridded forecasts at 5km resolution
These models provide good resolution of local and mesoscale features
ModelModel NAM12NAM12 ARPSARPS
Horizontal Horizontal ResolutionResolution 12 km 4 km
Vertical Vertical ResolutionResolution 60 layers 40 layers
Temporal Temporal ResolutionResolution 3 hr 0.5 hr
Turbulence Turbulence SchemeScheme
Mellor-Yamada 2.5-Level Closure
1.5 TKE Closure
Model Run Model Run UsedUsed 0Z 3Z
Table 1: Model ResolutionsTable 1: Model Resolutions
MethodsMethods The study was conducted 1-30 Jun
2005 The ‘nighttime’ hours of 03Z to
12Z (11pm-8am EDT) were considered for each day
To evaluate development of nighttime land breezes
To correspond with the 3Z ARPS run
Seven parameters evaluated Five sites within coastal zone of
the WFO Melbourne CWA
ParametersParameters
Surface Wind Direction (°)
Surface Wind Speed (kts)
Surface Temperature (°F)
100 ft Temperature (°F)
200 ft Temperature (°F)
500 ft Temperature (°F)
1000 ft Temperature (°F)
Inversion Height (m)
Table 2: Evaluated Forecast ParametersTable 2: Evaluated Forecast Parameters
Figure 1: Sites evaluated in the study (Pink Dots) within the NWS Melbourne CWA Figure 1: Sites evaluated in the study (Pink Dots) within the NWS Melbourne CWA
(shaded in gold). Other cities provided for reference(shaded in gold). Other cities provided for reference
(009)
Model PerformanceModel Performance
Table 3: Averages for June 2005Table 3: Averages for June 2005
ModelModelSurface Wind Surface Wind
DirectionDirectionSurfaceSurface Wind Wind
SpeedSpeedSurface Surface
TemperatureTemperature
Difference (°) Difference (kts) Difference (°F)
Model Average-Model Average-ARPSARPS -25.92 -1.88 1.58
Standard Standard Deviation-ARPSDeviation-ARPS 17.17 2.51 1.41
Model Average-Model Average-NAM12NAM12 -5.19 -2.75 0.03
Standard Standard Deviation-Deviation-
NAM12NAM1218.29 2.28 1.53
Model PerformanceModel Performance The NAM12 performed better overall in
forecasting wind direction and surface temperature ARPS performed better in direction at Buoy 41009
The ARPS provided more accurate forecasts for wind speeds at all sites
Both models show a tendency to forecast higher winds than observed Most noticeable at Buoy 41009 and TTS Possibly due to the model handling of nighttime surface
boundary layer over water
TS Arlene – 10 June 2005TS Arlene – 10 June 2005TS Arlene passed into the Gulf of Mexico and west
of the Florida peninsula between 10 and 11 June
Figure 2: 10 June 2005 12Z Surface Map Figure 2: 10 June 2005 12Z Surface Map http://www.hpc.noaa.govhttp://www.hpc.noaa.gov
TS Arlene – 10 June 2005TS Arlene – 10 June 2005 ARPS
No error in direction forecast at VRB Forecasted winds tended more southerly than observed
directions Average difference at DAB was -25.00°
NAM12 No error in direction forecasts at MLB
Least Accurate at DAB (-22.50°) Speed most accurately forecasted at DAB (-1.50kts) and VRB
(-1.75kts)
Both models least accurate speed forecasts at TTS and 009 Forecast errors may be due to inaccurate forecasting of
storm position
Figure 3: NAM12 and ARPS Forecast vs Observed Wind Direction on 10 June 2005 at DABFigure 3: NAM12 and ARPS Forecast vs Observed Wind Direction on 10 June 2005 at DAB
0102030405060708090
100110120130140150160170180
3 6 9 12Hour (UTC)
Dire
ctio
n (d
egre
es)
Forecasted-NAM12 Forecasted - ARPS Observed
Figure 4: ARPS NAM12 Forecast vs Observed Wind Speed on 10 June 2005 at TTS and 009Figure 4: ARPS NAM12 Forecast vs Observed Wind Speed on 10 June 2005 at TTS and 009
0123456789
1011121314151617181920212223
3 6 9 12Hour (UTC)
Win
d Sp
eed
(kts
)
Forecasted NAM12 - 009 Forecasted ARPS - 009 Observed - 009 Forecasted NAM12- TTS Forecasted ARPS-TTS Observed - TTS
Summary and RecommendationsSummary and Recommendations
Wind direction and speed can have a variety of impact on weather and operations
The NAM12 performed better overall in wind direction and surface temperature, the ARPS in wind speeds
Tendency to forecast higher winds than observed
Forecast errors during Arlene possibly due to misplacement of storm
Longer time period/More hours needed for more comprehensive comparison
AcknowledgementsAcknowledgements
A special thanks to the National Weather Service Office in Melbourne, Florida for data and
assistance
ReferencesReferences Case, J.L. 2002: Final Report of Land-Breeze Forecasting. NASA Contractor CR-2002-211181,
Kennedy Space Center, FL, 56 pp.
NOAA-National Weather Service. [http://www.noaa.gov]. Accessed 15 Jul 2005.
North American Surface Analysis. Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov]. Accessed 15 Jul 2005.
Operational Models Matrix. Meteorology Education and Training. [http://meted.ucar.edu/nwp/pcu2/index.htm] Accessed 15 Jul 2005.
Real Time Operational and Analysis Network (ROMAN). [http://raws.wrh.noaa.gov/roman/]. Accessed 15 Jul 2005.
Tropical Weather Summary-June 2005. National Hurricane Center [http://www.nhc.noaa.gov]. Accessed 15 Jul 2005.
Weather Observation Station Record. National Climatic Data Center. [http://www.ncdc.noaa.gov]. Accessed 15 Jul 2005
Xue, M., Droegemeier, K., Wong, V. "The Advanced Regional Prediction System and Real-time Storm-scale Weather Prediction." International Workshop on Limited-area and Variable Resolution Models. Beijing, China, October, 1995.
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