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Observations of ClearAir Boundaries

This data summary and collection strategy explores the use of the UMass "Tornado Radar" during the International H2O Project (IHOP). The radar's operations and deployment modes are discussed, including VAD, vertical antenna, stationary RHI, and rolling RHI. The challenges and complications of data collection are also examined.

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Observations of ClearAir Boundaries

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  1. Observations of ClearAir Boundaries Made By the UMass “Tornado Radar” During the International H2O Project (IHOP) Data Summary and Collection Strategy Christopher Weiss & Howard Bluestein University of Oklahoma Norman, Oklahoma

  2. Radar Spec Basics • Boresighted camera on dish (calibrated) • Operating frequency = 95 GHz (l=3 mm) • Beamwidth = 0.18 degrees • Three experimental modes for clear-air:

  3. Operations During IHOP_2002 June 9 (dryline) June 10 (dryline) June 3 (cold front) Deployments: 3 rolling RHI 2 stationary RHI 2 VAD Deployments: 2 rolling RHI 2 VAD Deployments: 1 stationary RHI May 22 (dryline) Deployments: 4 rolling RHI 2 stationary RHI 2 VAD 1 vertical antenna X-sect

  4. Data Collection StrategiesMode #1 - VAD 5/22/02 – moist side VAD • Synthesize vertical wind profile from elevated sector scan (~ 220 degrees in azimuth, at 45 degrees elevation) • Six VADs performed during IHOP, three on each side of the dryline. W

  5. Data Collection StrategiesMode #2 – Vertical Antenna • Temporal/spatial profile of vertical velocity • Performed on May 22 dryline

  6. Data Collection StrategiesMode #3 – Stationary RHI • Five such deployments during IHOP • Drawback: No Vr decomposition into u/w • Vertical sectors perpendicular to feature of interest • May 22 - Dryline retrogrades through truck • June 9 – Dryline advances past truck

  7. DZ Dryline Retrogression 5/22/02 W 00:36 UTC (5/23) VE

  8. DZ Dryline Retrogression 5/22/02 W 00:37 UTC (5/23) VE

  9. DZ Dryline Retrogression 5/22/02 W 00:43 UTC (5/23) VE

  10. DZ Cold Front 6/3/02 NW 19:49 UTC VE

  11. DZ Cold Front 6/3/02 NW 19:51 UTC VE

  12. DZ Cold Front 6/3/02 NW 19:56 UTC VE

  13. Data Collection StrategiesMode #4 – Rolling RHI • Nine rolling RHIs during IHOP (all across drylines) • GPS data critical • Use pseudo-dual Doppler principles for u/w decomposition in lobe but…more complicated than airborne technique.

  14. Dryline 5/22/02 DZ 00:30 UTC (5/23) W

  15. DZ Dryline 6/10/02 E 20:00 UTC VE (uncorrected)

  16. Complications • Subtraction of truck velocity is delicate. • Accurate GPS position, velocity important • Pitch of truck • Uncertainty of GPS elevation data • Translation and development of feature • “Stationarity assumption” • Uncertain boundary positions • Sensitivity and range • Irregular weave pattern (i.e., varying angle of intersection between two radar looks)

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