Real-Time Dissemination of Hurricane Wind Fields Determined from Airborne Doppler Radar John Gamache NOAA/AOML/Hurricane Research Division Collaborators: Joseph Griffin, Peter Dodge, Nancy Griffin Supported by NOAA Joint Hurricane Test Bed

Project Goals Develop a hurricane wind-field analysis in “real time” and make it available to hurricane specialists at the Tropical Prediction Center Send reliable observations to the Environmental Modeling Center at NCEP for assimilation testing in numerical simulations

Airborne Radar on NOAA P-3 Airborne Radar 1)Scanning axis along aircraft fuselage 2)3-cm wavelength 3)Measures reflectivity (precipitation content) 4)Measures radial velocity from aircraft FOR MORE INFO...

Jorgensen et al., 1983, J. Climate Appl. Meteor, 22,

Present Analysis Software Reliable--Works on multiple platforms Mass-conserving Consistent to within 1-2 m/s with Doppler observations Operates in research mode –Researcher has plenty of time to make decisions regarding errors/assumptions –Final analysis may take years

Hurricane Humberto 23 Sep UTC Altitude: 1km Tangential wind (m/s) Radar Reflectivity (dBZ) And wind field

Hurricane Humberto 23 Sep UTC Azimuth 350 Vertical cross-section of tangential and vertical winds and winds within the plane range from center (km)

Main sources of error from NOAA P-3 Airborne Doppler Radar Doppler radial velocity ambiguity Reflection from sea surface Incorrectly measured antenna pointing direction Noise

Doppler Radial Velocity Ambiguity Velocities determined from radar pulse phase measurements -180 o to 180 o phase range –Corresponds to a radial velocity range –P3--range from to 12.9 up to to 25.8 meters per second--Nyquist velocity Angles 180 o are ambiguous –Corresponding velocity aliased or “folded” –True velocity is measured aliased velocity plus 2 times a multiple of Nyquist velocity

Noise Receiver Noise--power threshold Meteorological Noise –Turbulence in boundary layer –Turbulence in outflow from convection

Reflection from sea surface Main antenna lobe –Beam width vs precipitation content Side lobe –Annular--radius is height of aircraft –Fairly weak “Second trip”--confusion with previous pulse –High spectral width –Usually removed easily by noise edit

Antenna pointing direction errors Pointing direction relative to aircraft Aircraft attitude HRD has software to estimate these errors

Accomplishments Sea-surface reflection removal software developed/preliminary test Speckle removal developed Minor bugs in present de-aliasing removed Two-dimensional de-aliasing scheme development begun Preliminary discussions with EMC on structure of “superobs”

Doppler Radial Velocity Hurricane Humberto UTC 23 Sep 2001

Doppler Radial Velocity Hurricane Humberto UTC 23 Sep 2001

Doppler Radial Velocity Hurricane Humberto UTC 23 Sep 2001

Doppler Radial Velocity Hurricane Humberto UTC 23 Sep 2001

Research QualityAutomatic Comparison of Analyses Created from Research-Quality and Automatically Edited Data At 1 km level in Hurricane Humberto 2330 UTC on 23 September 2001

Next Tasks Improve two-dimensional de-aliasing –Produce consistent velocities within contiguous regions of data –Ensure overall velocity in each contiguous region is consistent with expected hurricane flow

Next Tasks Begin interaction with NCEP/EMC –Determine structure of “superobs” –Begin determination of data error covariance of Airborne Doppler radial velocity measurements Install new software on airborne workstations for 2004 Hurricane Season

Future Tasks Produce test wind analysis aboard aircraft during 2004 Hurricane Season Test sending a prototype superob by end of 2004 Hurricane Season Develop analysis display for Hurricane Specialists during “off season” Begin determination with EMC of Doppler data error covariance Send wind analysis to specialists during 2005 Hurricane Season Continue testing superob transmission during 2005 Hurricane Season