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Radar Sea Level Pressure Remote Sensingfor Improvements in Hurricane Predictions
04 March 2008 Charleston, SC
Qilong Min
Roland Lawrence
Bing Lin, Yongxiang Hu, Steven Harrah, and Dion Fralick
Langley Research Center
Hampton, VA 23681
Session 3: Observing the Tropical Cyclone and its Environment
[email protected] 757.864.1805
62nd IHC Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
OUTLINE
• Need & Benefits
• Measurement
• Development Status
• Conclusion
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moored buoy
dropsonde
Off-Shore Air Pressure Measurements
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
• Current operations require in situ measurement (few buoys & dropsonde)- sparse measurements in time and space- exposes air crews to a variety of dangers
• Greatly improves hurricane forecasts(intensification and track)
• Improved understanding of global pressure field (dynamics and interactions)- large area coverage & relatively rapid revisit intervals- lessen operational dangers & costs (long-term)
drift buoy
Added Benefits of Remotely Sensed Measurements
62nd IHC Example Benefits(Ivan’04 & Fran’97)
998.7mb
350 km landfall error reduced to < 100 km
actual track
with P data
Control
951.5mb
pre
ssu
re v
ari
ab
ilit
y:
882~
1020m
b
error: 1.5mb (47 mb change)
no P data
with P data
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
72hr Forecasts
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Run
Distance Error (km)
SLP (hPa)
Max Winds
(kt)
Landfall Time
(UTC)Observation 923 110 12:00
Aug. 25-c 670 959 43 3:00
Aug. 25-p 335 933 78 9:00
Aug. 26-c 266 939 80 6:00
Aug. 26-p 70 932 84 12:00
Improvements in hurricane forecasts are demonstrated using press. measurements compared with control predictions and the observed track of Katrina.
Key predictions in hurricane intensity and track are significantly improved using remotely sensed pressure measurements (p) compared to controlled models (c).
Aug 29
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
Example Benefits(Katrina)
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Oxygen in the atmosphereattenuates the transmitted signal
– less at lower freq. and more at higher freq.
The amount of attenuation is directly related to
barometric pressure and altitude.
f or 1/
PPRecRec
Atte
nu
atio
n
Calibrated PRec
w/o Attenuation
Aircraft/Spacecraft-BasedQ-Band (50-56GHz) Radar
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane PredictionsMeasurement Concept
Radar Attenuation by Oxygen Barometric Sensor (RAOBS)
T/R Several (1-6), Narrow-Band (~100MHz) Signals
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Most of the variability (shown here) is due to global atmospheric profile variations: temperature, water vapor, clouds, etc.
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
Simulated Radar Results
PR(1)PR(2)
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Ground Tests (LaRC)
RAOBS PoC InstrumentInstalled on Mobile Radar Lab
Calibration Target• nearly spherical reflector
• ~300m clear range
ProjectedBeamwidthProjected
Beamwidth
Calibration Target• nearly spherical reflector
• ~300m clear range
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
Radar Attenuation by Oxygen Barometric Sensor (RAOBS)
62nd IHC Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
Varina-Enon BridgeI-295 South of Richmond, VA
Approx. 150’ above James River
Ground Tests
Measure Water NRCSOver Wide Inc. Ang.
Support Satellite Design
Supported by VDOT
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Port Side View
C E N T E R
HELICOPTERS, INC.
Rail Mount
Box Frame
Antennas
Internal Rack (VNA)
Cable Routing
Bell 407
Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
Flight Hardware Installation
RAOBS PoCInstrument
Flight Tests Q3 FY08
62nd IHC Radar Sea Level Pressure Remote Sensing for Improvements in Hurricane Predictions
±10o
LEO (705 km)
RAOBS
Satellite Concept
Torbit ~98 min
250 km
~ ½ o
6 km
Design Est.:MassPower
& DL Comm.TBD – FY’08
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ConclusionsRadar Sea Level Pressure Remote Sensing for
Improvements in Hurricane Predictions
• RAOBS Concept of Operation Instrument - Validated RAOBS Measurement Concept - Completed Ground Tests - Developed Flight Installation (awaiting FAA cert) - Looking for additional flight opportunities
• RAOBS operational model shows significant improvements to our understanding of global pressure fields (dynamics and interactions)
• Significant improvements to hurricane forecasts (intensification and track)- Improves forecast reliability- Increases warning times - Decreases social/economic impact
• Beginning satellite design and subsystem definitions- Looking for collaborative partners / future satellite projects
