G O D D A R D S P A C E F L I G H T C E N T E R NASA High-Altitude Precipitation/Wind Radars for Hurricane Research Gerald Heymsfield NASA/Goddard Space Flight Center 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).

G O D D A R D S P A C E F L I G H T C E N T E R 2 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 (>24 hours), high-altitude (>18 km) capability.  More than a decade of high-altitude Doppler wind measurements from ER-2 aircraft over weather systems including tropical storms

G O D D A R D S P A C E F L I G H T C E N T E R Current Hurricane Research Using ER-2 Doppler Radar (EDOP) X-band (9.6 GHz) Nadir pointing beam -> derive vertical motions Fixed forward pointing beam (30 degrees) for derivation of along-track winds and cross-polarization measurements. First flown 1995, developed early 1990’s.

G O D D A R D S P A C E F L I G H T C E N T E R 4 Cloud Radar System (CRS) W-Band (94 GHz) >CloudSat simulator >Strongly attenuated by precipitation, large ice. CRS (94 GHz)EDOP (9.6 GHz) -->Dual-frequency (X, W- Band) provides information on hydrometeors

G O D D A R D S P A C E F L I G H T C E N T E R 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 30 o, 35 o conical scan funded by NASA to complement Lidar Wind Sounder (LAWS) Radar Wind Sensor (RAWS) (Moore et al., 1992) Spaceborne radar wind measurement study (X- and Ka-band) with 30 o, 35 o conical 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

G O D D A R D S P A C E F L I G H T C E N T E R 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 IR&D Goddard Space Flight Center Aircraft: ER-2?, Global Hawk Completion of basic system: 6 months 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 IR&D Goddard Space Flight Center Aircraft: ER-2?, Global Hawk Completion of basic system: 6 months

G O D D A R D S P A C E F L I G H T C E N T E R 7 NASA High-Altitude Aircraft and HUAS WB57 Global Hawk Altitude (kft) to 65 Maximum Duration (hrs) Maximum Payload (lbs) 2,900 6,000 2,000-3,000 Max. Microwave Aperture (ft) WB-57 ER-2 Not Yet Operational 1 Improvements in progress TBD 2 Conical scan requires large opening

G O D D A R D S P A C E F L I G H T C E N T E R 8 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.

G O D D A R D S P A C E F L I G H T C E N T E R 9 URAD Configuration in Global Hawk Scanning and fixed nadir antenna Interface for Global Hawk Two-axis positioner to achieve conical scan and elevation adjustment. URAD was designed for installation with minimal GH modifications

G O D D A R D S P A C E F L I G H T C E N T E R URAD Hardware TWT transmitter, high voltage power supply and modulator Two axis positioner to achieve elevation and azimuth scan Nadir Magnetron Subsystem Scanning Receiver hardware

G O D D A R D S P A C E F L I G H T C E N T E R 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  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

G O D D A R D S P A C E F L I G H T C E N T E R HIWRAP Measurement Concept Many independent radial wind measurements within grid volume are used to calculate wind vector Two look angles and two frequencies

G O D D A R D S P A C E F L I G H T C E N T E R 13 HIWRAP Measurement /Accuracy Requirements Based on 10 W Ka-band and 30 W Ku-band power amplifiers

G O D D A R D S P A C E F L I G H T C E N T E R 14 HIWRAP in Global Hawk Antenna feedsAntenna reflector Scanner, slip ring & fiber optical rotary joint Aircraft floor Mounting frame Radome Power amplifiers & RF front end Radar RF/IF HIWRAP was designed for installation in GH with minimal modifications

G O D D A R D S P A C E F L I G H T C E N T E R 15 WB-57 Test Flights Planned Summer 2008 WB-57 6-foot pallet Radome for Ku- and Ka-band

G O D D A R D S P A C E F L I G H T C E N T E R 16 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 -> Summer  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---> opportunity to remotely measure winds in precipitation-filled and clear regions.

G O D D A R D S P A C E F L I G H T C E N T E R 17 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 Tropospheric Wind Lidar Technology Experiment (TWiLiTE) Instrument Incubator Program Source: Bruce Gentry, NASA/GSFC UV Laser Rotating telescope Doppler Receiver TWiLiTE system integrated on WB57 3 foot pallet