NASA High-Altitude Precipitation/Wind Radars for Hurricane Research

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NASA High-Altitude Precipitation/Wind Radars for
Hurricane Research
Gerald Heymsfield NASA/Goddard Space Flight
Center (Gerald.Heymsfield_at_nasa.gov) Lihua Li
/University of Maryland Baltimore/GEST James
Carswell /Remote Sensing Solutions, Inc.

• Outline
• Current high-altitude radars for hurricane
  research with NASA ER-2
• Future directions with tropospheric wind
  measurements and surface winds from high-altitude
  aircraft and high-altitude long endurance UAS
  (HALE).

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Science Drivers

• Targeted observations and real-time information
  from hurricanes other extreme weather events in
  remote regions.
• Tropospheric wind measurements with higher
  spatial and temporal resolution than currently
  available from lower altitude aircraft
• HALE such as Global Hawk currently provide
  long-duration (gt24 hours), high-altitude (gt18 km)
  capability.
• More than a decade of high-altitude Doppler wind
  measurements from ER-2 aircraft over weather
  systems including tropical storms

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Current Hurricane Research Using ER-2 Doppler
Radar (EDOP)X-band (9.6 GHz)

• Nadir pointing beam -gt derive vertical motions
• Fixed forward pointing beam (30 degrees) for
  derivation of along-track winds and
  cross-polarization measurements.
• First flown 1995, developed early 1990s.

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Cloud Radar System (CRS)W-Band (94 GHz)
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Radar Wind Measurements Motivating Factors for
Conical Scan

• Radar Wind Sensor (RAWS) (Moore et al., 1992)
• Spaceborne radar wind measurement study (X- and
  Ka-band) with 30o, 35oconical scan funded by NASA
  to complement Lidar Wind Sounder (LAWS)

Imaging Wind and Rain Airborne Profiler (IWRAP)
(Esteban, Carswell..2005) P3-based C- and
Ku-band, four incidence angle, conical scanner
flown in hurricanes the past seveal years
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NASA Conical Scan Radars in Development

• High-Altitude Imaging Wind and Rain Profiler
  (HIWRAP)
• Ku, Ka-Band (14 and 35 GHz) radar funded by NASA
  Instrument Incubator Program (IIP) Aircraft
  WB-57, Global Hawk
• Completion of basic system 15 months
• UAV Radar (URAD)
• X-Band (9.3, 9.4 GHz) funded IRD Goddard Space
  Flight Center
• Aircraft ER-2?, Global Hawk
• Completion of basic system 6 months

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NASA High-Altitude Aircraft and HUAS
Global Hawk
WB-57
ER-2
WB57
Not Yet Operational
Altitude (kft) 70
631 60 to 65 Maximum Duration
(hrs) 8 51
30 Maximum Payload (lbs)
2,900 6,000
2,000-3,000 Max. Microwave Aperture (ft) 2
2.5 4.2
4.3
1Improvements in progress TBD 2Conical scan
requires large opening
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URAD Measurement Concept

• Initial development 2004 Atlantic Seedlings and
  Hurricane Experiment (ASHE) proposal using Global
  Hawk to study TS cyclogenesis off the coast of
  Africa
• Nadir capabilities of EDOP, plus a second conical
  scanning beam to provide estimates of horizontal
  winds in cloud and the ocean surface winds.
• Conical scan provides 3-D surveillance of
  precipitation, horizontal winds in precip. and
  surface winds.
• Low cost solution using existing radar
  technologies.

X-Band, separate nadir (9.4 GHz) and scanning
radar (9.3 GHz) subsystems, fully scanable
antenna up to 35 degree elevation.
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URAD Configuration in Global Hawk
URAD was designed for installation with minimal
GH modifications
Interface for Global Hawk
Two-axis positioner to achieve conical scan and
elevation adjustment.
Scanning and fixed nadir antenna
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URAD Hardware
Nadir Magnetron Subsystem
TWT transmitter, high voltage powersupply and
modulator
Two axis positioner to achieve elevation and
azimuth scan
Scanning Receiver hardware
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HIWRAP Development

• Technology development emphasis.
• Utilize low power solid-state transmitter instead
  of high power tube-based transmitter - more
  suitable for high-altitude and space
• Develop single aperture antenna for two beams and
  two frequencies.
• Develop high altitude, power efficient real-time
  digital receiver and processor
• GPM frequencies

3D winds (grid point retrieval) and
reflectivity Two frequencies and two incidence
angles to increase the number independent wind
measurements
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HIWRAP Measurement Concept
Two look angles and two frequencies
Many independent radial wind measurements within
grid volume are used to calculate wind vector
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HIWRAP Measurement /Accuracy Requirements
Based on 10 W Ka-band and 30 W Ku-band power
amplifiers
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HIWRAP in Global Hawk
Scanner, slip ring fiber optical rotary joint
Aircraft floor
Power amplifiers RF front end
Mounting frame
Radar RF/IF
Antenna feeds
Antenna reflector
Radome
HIWRAP was designed for installation in GH with
minimal modifications
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WB-57 Test Flights Planned Summer 2008
WB-57 6-foot pallet
Radome for Ku- and Ka-band
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Summary

• Radar-based winds using conical scan from above
  hurricanes and other extreme weather events is
  promising approach for high-altitude aircraft,
  HALE, and space.
• HIWRAP hardware completion and flight testing on
  WB-57 aircraft -gt Summer 2008.
• Completion of basic URAD system by Fall 2007
• Migrate both radars to Global Hawk when one
  becomes available.
• Lidar-based wind instrument (TWiLiTE) due for
  completion for WB-57 about same time as
  HIWRAP---gt opportunity to remotely measure winds
  in precipitation-filled and clear regions.

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Tropospheric Wind Lidar Technology Experiment
(TWiLiTE) Instrument Incubator Program

• TWiLiTE will demonstrate, for the first time,
  downward looking wind profiles from 18 km to the
  surface obtained with an airborne direct
  detection scanning Doppler lidar
• Serves as a system level demonstration and as a
  technology testbed
• Leverages technology investments from multiple
  sources
• TWiLiTE is a collaboration of government
  (NASA/NOAA), university and industry partners

Rotating telescope
Doppler Receiver
UV Laser
TWiLiTE system integrated on WB57 3 foot pallet
Source Bruce Gentry, NASA/GSFC