Summer Cloudtop Temps by AVHRR and Rawinsonde

1
Summer Cloudtop Tempsby AVHRR and Rawinsonde

• LT Brady Brown, USN
• OC3570 Summer 2001

2
Summer Objectives

• Cloud-type correlation with obs.
• Low stratus measurements
• vs. winter multi-layer structure.
• Rawinsonde data handling MATLAB.
• Teravision image manipulation
• both for thesis preperation.
• Coastal meteorology, RAOB, skew-T
• for better understanding.

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Procedures Images

• Time Correlation overpass downcast delay.
• Met. Conditions foggy/clear, trajectory range.
• Subtrack Distance nadir, image stretch,
  geonav.
• Launch Delay concurrent events, watches.

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Procedures Local OPAREA

• Ref Cypress Point.

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AVHRR Parameters

• Channel 4 10.3 11.3 ?m (928 cm-1).
• IFOV 1.1 km (1.41 mrad aperture).
• Brightness Temperature - 0.12 K.
• Data Precision 10-bit HRPT (1024 shades).
• Scan Rate 2048 pts, 360 scan/min (16 min).
• Geonavigation boundary lock,
• clearest point, Crescent City / Mt Shasta.

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Channel 4 Spectral Response
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Image One 2 Aug, 2057Z, 1357

• Conditions 7/8, up through hole, 311o at 5
  kts.
• Overpass 2112Z (15 min late).
• Subtrack 497.6 NM from Cypress Point.
• Ch. 4 Temp 12.96o C.

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Point One
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Image Two 3 Aug, 2128Z, 1428

• Conditions 8/8, 7 mi vis underneath, 333o 3
  kts.
• Overpass 2101Z (27 min early).
• Subtrack 723.6 NM from Cypress Point.
• Ch. 4 Temp 11.60o C (12.22o C nearby).

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Point Two
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Image Three 8 Aug, 0131Z, 1831

• Conditions clear above, fog around, 296o 4
  kts.
• Overpass 0050Z (41 min early).
• Subtrack Only 15.9 NM (Best pass).
• Ch. 4 Temp 13.28o C (27o C on coastline).

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Point Three
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Image Four 8 Aug, 2135Z, 1435

• Conditions 8/8, clear just offshore, nil wind.
• Overpass 2149Z (14 min late).
• Subtrack 331.1 NM.
• Ch. 4 Temp 13.07o C (constant offshore).

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Point Four
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Image Five 9 Aug, 0120Z, 1820

• Conditions 8/8, convection, 146o at 2 kts.
• Overpass 0038Z (42 min early, sonde swap).
• Subtrack 251.1 NM.
• Ch. 4 Temp 11.87o C (cold patches, hot hills).

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Related Products

• NRL Cloud Type (NOGAPS gt 15,000 ft)
• Best for aviation OTSR, deep convective
  supercells.
• NRL Fog Product (4 x 4 1.1 km cell routine)
• Nightime channel 4-2 comparison.
• NRL Ash Trajectory
• Daytime channel 4-5 comparison.
• SCANDIA 98 Cloud Type (shore discrepancy)
• Ch. 1-2 reflectance (ice/H2O), 3-4 brightness
  diff.
• Intl. Sat. Cloud Clim. Proj. D2 Cloud Type
• Pressure vs Tau (optical thickness) vs
  Reflectance.

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Conclusions

• 66 passes 27 sondes gt 11 correlated gt 9 cloudy
• gt 5 .mat files gt Only 4 good matches.
• Interpolate times, positions, sonde
  trajectories
• (45 min up/down, 20.76 km travel, 82.3 m/s).
• Max delta correlates well with surface wind.
• Did not integrate delta over time or height
• from ballon launch position of boat.
• Teravision beats the pants off XVU!
• (geonavigation, annotation, precision)

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References

• NRL http//kauai.nrlmry.navy.mil/sat_products.h
  tml
• SCANDIA
• http//www.smhi.se/sgn0106
• ISCCP http//daac.gsfc.nasa.gov/CAMPAIGN_DOCS/F
  TP_SITE/INT_DIS/readmes/isccp_d2.html200