# Presentation: 767498

## 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**
**Scanning axis along aircraft fuselage**
**3-cm wavelength**
**Measures reflectivity (precipitation content)**
**Measures radial velocity from aircraft**

**FOR MORE INFO...**

**http://www.aoml.noaa.gov/hrd/project2003/doppler.html**

## Jorgensen et al., 1983, J. Climate Appl. Meteor, 22, 744-757

**Jorgensen *****et al., *****1983, *****J. Climate Appl. Meteor, *****22, 744-757**

## 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**

## Slide 6

## 0

**range from center (km)**

**0**

**10**

**35**

**5**

**10**

**15**

## 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 -12.9 to 12.9 up to -25.8 to 25.8 meters per second--Nyquist velocity**
**Angles < -180****o**** or > 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
- 231754 UTC
- 23 Sep 2001

## Doppler Radial Velocity

- Hurricane Humberto
- 232842 UTC
- 23 Sep 2001

## Doppler Radial Velocity

- Hurricane Humberto
- 232855 UTC
- 23 Sep 2001

## Doppler Radial Velocity

- Hurricane Humberto
- 232901 UTC
- 23 Sep 2001

## Research Quality

**Research Quality**

**Automatic**

**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**