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Tribune, KS: 25 May 2010. RAPID-SCAN DOW RADAR OBSERVATIONS OF TORNADOES DURING VORTEX2 2009 and 2010 Joshua Wurman , Karen Kosiba , Paul C. Robinson Center for Severe Weather Research. Rapid -Scan. DOW6. Rapid -Scan. DOW6. DOW7. DOW7. DOW6. Rapid -Scan. Rapid -Scan. DOW6.

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Tribune, KS:

25 May 2010

RAPID-SCAN DOW RADAR OBSERVATIONS OF TORNADOES DURING VORTEX2 2009 and 2010

Joshua Wurman, Karen Kosiba, Paul C. Robinson Center for Severe Weather Research

Rapid-Scan

DOW6

Rapid-Scan

DOW6

DOW7

DOW7

DOW6

Rapid-Scan

Rapid-Scan

DOW6

DOW7

DOW7

Rapid-Scan DOW is an NSF facilityDOWs are supported by NSF-ATM-0734001 and -0966095 and -0946926

Analysis supported by NSF-ATM-0801041

VORTEX2 supported by SPO grant NSF-ATM-0724318 and others

Observations:

Green = DOW7 radius and locations

Maroon = DOW6

Blue = Rapid-Scan

Observations:

Green = DOW7 radius and locations

Maroon = DOW6

Blue = Rapid-Scan

Rapid oscillations resolved by Rapid-Scan,

not by DOW-7

Bovina, CO: 11 June 2010

DOW 6 at 0112:51 UTC

Booker, TX:

13 June 2010

9730 MHz

6.2o

Two Simultaneous Tornadoes

Rapid-Scan DOW at 0112:55 UTC

Analysis supported by NSF-ATM -0801041

DOWs supported by NSF-ATM-0734001 and -0966095 and -0946926

VORTEX2 supported by SPO grant

NSF-ATM-0724318 and others

Right: Map detailing observations obtained by the Rapid-Scan DOW (blue) and DOW 7 (green). Circles denote radius of maximum winds observed by respective radars. Note the additional observations available from the Rapid-Scan DOW.

Below: An example scan through the tornado by the Rapid-Scan DOW. Allfour elevations were taken at 23:40:39 UTC. Note the lack of the reflectivity eye at the four degree elevation scan.

9649 MHz

5.3o

Rapid-Scan

Observations

DOW7

Observations

Rapid-Scan

Observations

DOW7

Observations

DOW-Rapid-Scan Comparison (Above):Comparisons of DOW-measured Doppler velocity (left) and radar reflectivity (right) as observed by DOW 6 (top) and Rapid-scan DOW (bottom), indicating good agreement on both large-scale and fine-scale (black circles) circulations.

1.3 °

1.3 °

0.5 °

Allscans taken at 23:40:39 UTC

0.5 °

9562 MHz

4.0o

  • Six simultaneous elevations scanned
  • Full volume updates every seven seconds.
  • 50 or 25-meter gate spacing
  • 0.8 – 0.9 degree beam width
  • 4D resolution @ 2 km
  • 28 m x 30 m x 25 m x 7 s = 150,000 m3s

9478 MHz

3.0o

DOW7

13 km south

DOW7

13 km south

Combined DOW7 and Rapid-Scan measurements:

Captured genesis and demise

9354 MHz

1.3o

3.0 °

3.0 °

4.0 °

4.0 °

9310 MHz

0.5o

Simultaneous Scans at Multi-Levels

Above: DOW-measured Doppler velocity (left) and radar reflectivity (right) from each channel of the rapid-scan radar. Time of observation was 01:09:20 GMT

Above: An example Rapid-Scan observation of velocity (left) and reflectivity (right) at a single elevation angle. The structure of the inner debris ring is well captured.

Left: Delta-V as measured by DOW 7 (green) and Rapid-Scan DOW (red), capturing tornado genesis, intensification and demise.

Above: The entire evolution of the Booker, TX tornado was captured by the DOW radar network.

1-2 Minute Oscillations Observed

Seven-second observations of the Rapid-Scan DOW delta-V at three different elevations (far left). An FFT analysis of channel 4 reveals periodic oscillations in tornado intensity approximately every 1.1-1.8 minutes (center). These ~ 1 minute oscillations are not captured by the 1-minute DOW7 observations (right).

Goshen Co., WY:

5 June 2009

Left: Axisymmetric radial and tangential wind profiles derived from the Rapid-Scan DOW using the GBVTD technique at 130 m AGL. Divergence is present inside the radius of maximum winds, while farther outside the radius of maximum winds weak inflow is observed.

GBVTD Reveals Outflow Inside RMW:Ground-based velocity track display (GBVTD) analyses derived from 7-second Rapid Scan DOW observations (above). Color contours indicate tangential winds and vectors denote the secondary circulation.

2214:07 2214:07 2214:14 2214:21 2214:28 2214:35 2214:42 2214:49

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan

DOW 7

Rapid-Scan

Rapid-Scan

a

b

2214:57 2214:57 2215:04 2215:11 2215:18 2215:25 2215:32 2215:39

DOW 7

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan

Rapid-Scan Reveals Fast Evolution: (Above) Evolution of the velocity (left, in images) and reflectivity (right, in images) from 2214:07-2115:39 UTC. DOW 7 (outlined in magenta) completes a volume approximately every one minute , whereas the Rapid-scan DOW (outlined in blue) completes a volume every seven seconds. Images are shown for the lowest elevation scan for both radars. Note the rapid evolution of the tornado that occurs on timescales of < one minute.