COMPARING COAMPS WITH IN SITU DATA

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COMPARING COAMPS WITH IN SITU DATA
LT Tara Lambert OC 3570 16 MAR 2005
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DATA COMPARISON

• Wind Speed and Wind Direction
• COAMPS vs. Rawinsonde
• Ascent data
• Using forecast periods in lieu of analysis to
  compare data
• COAMPS vs. Aircraft
• Using forecast periods in lieu of analysis to
  compare data

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COAMPS 3.0

• 3km Horizontal Resolution
• Vertical Resolution
• 1010mb to 50mb
• 50mb intervals
• Analysis time of 00Z and 12Z
• 01FEB to 08FEB
• 12hr forecast of each analysis period at 3hr
  increments.

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RAWINSONDE DATA

• 17 Rawinsondes
• 8 Leg I
• 9 Leg II
• 4 of 17 had no data above 700mb
• 3 on Leg I
• 1 on Leg II

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UV-18A TWIN OTTER

• 5 Hole probe Rosemount TAS
• Two flights
• 02FEB
• 50m (1010mb)
• 610m (950mb)
• 05FEB
• 50m (1010mb)
• 260m (985mb)

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ANALYSIS
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COAMPS vs. RAWINSONDE
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Coastal jet
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Coastal jet
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COAMPS UNDERESTIMATES
COAMPS OVERESTIMATES
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COAMPS vs. RAWINSONDE ANALYSIS

• COAMPS
• Increase of winds from 600mb to 400mb
• Winds under 20m/s (between 10-20m/s difference)
• Winds greater than 20m/s (more than 15m/s)
• Does not forecast U/L jet (300mb to 200mb)
• Coastal Jet was missed
• Consistency with direction except in light winds
• (less than 10m/s )
• RAWINSONDE
• Affected by eddies and turbulence in the low
  levels

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COAMPS vs. AIRCRAFT
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02FEB 1010mb (50m)
(1kt .5m/s)
Winds in knots
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05FEB 1010mb (50m)
(1kt .5m/s)
Winds in knots
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COAMPS vs. AIRCRAFT ANALYSIS

• COAMPS
• Consistent wind direction
• except in light winds
• Wind speed in good agreement

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CONCLUSION

• COAMPS
• Does not place the Jet Stream at the tropopause
  but has the strongest winds at approximately
  500mb.
• Problems with detecting coastal jet
• Does well with wind direction when it counts

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ACKNOWLEDGMENTS

• Prof Nuss for the COAMPS data
• Mary Jordan for help with MATLAB
• Sorry for leaving you.

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QUESTIONS?