# Presentation: 433618

## NEXRAD Technical Advisory CommitteeAP Clutter Mitigation Scheme

- NEXRAD Technical Advisory CommitteeAP Clutter Mitigation Scheme

- Cathy Kessinger
- Scott Ellis
- Joe VanAndel
- Norman, OK
- 19 November 2002

## AP Clutter Mitigation Scheme

**Objective -- automatic detection and suppression of AP clutter to improve hydrology and aviation products for the WSR-88D**

- Approach
- Separate AP clutter from precipitation                   (Radar Echo Classifier)
- Compensate precipitation reflectivity (Z-Comp)
- Define AP-affected areas on Clutter Filter Control map
- Clutter filter specification and control

## AP Clutter Mitigation Scheme

- REC and Z-Comp
- Open Radar Product Generator (ORPG)
- REC AP detection algorithm deployed Build 2
- ORPG Build 5:
- REC precipitation detection algorithm
- ORPG Build 6:
- Reflectivity compensation
- Automated clutter filter control
- Eventual implementation in Open Radar Data Acquisition (ORDA)
- Spectral processing techniques

## AP Clutter Mitigation Scheme

- Tested on WSR-88D and NCAR S-Pol data
- S-Pol provides polarimetric truth
- Particle identification algorithm
- Independent, objective truth
- Real-time statistical scoring of REC

## AP Clutter Mitigation Scheme

- STEPS, Jun-Jul 2000
- REC

- IMPROVE 2, Nov-Dec 2001
- REC and Z-Comp
- Confidence fields and statistical scoring

- IMPROVE 1, Jan-Feb 2001
- REC and Z-Comp

- IHOP_2002, Oklahoma, May-June 2002
- Continued confidence testing
- ZVW-Comp

## Schematic of AP Clutter Mitigation Scheme

- Base Data

- Radar Echo Classifier

- AP Clutter
- Detection

## Radar Echo Classifier (REC)

- Data fusion system that uses “fuzzy logic”
- Has three algorithms
- AP Detection Algorithm (APDA)
- Precipitation Detection Algorithm (PDA)
- Clear Air (bugs) Detection Algorithm (CADA)
- Working on confidence algorithms
- New algorithms
- Sea clutter detection
- Stratiform/convective precipitation partition, in progress
- Detection of small regions of clutter, in progress

## Reflectivity Compensation       (Z-Comp)

- Methodology
- Create compensation table assuming a Gaussian spectra with known clutter filter characteristics
- Use filtered V, W to get compensation value from table
- Maximum 15 dB compensation allowed

## IMPROVE II Case

- REC results
- S-Pol located in high terrain near Sweet Home, Oregon
- 0.5 deg

## Reflectivity Compensation

- Reflectivity compensation results

## Schematic of AP Clutter Mitigation Scheme

- Base Data

- Radar Echo Classifier

- Precipitation
- Detection

- Reflectivity
- Compensation

- Background Map Augmentation
- Clutter Filter Control
- and Specification

- AP Clutter
- Detection

## WSR-88D Clutter Filter Control

- Two methods to specify clutter filters
- Gate-by-gate background map
- Stationary targets
- Can be edited
- User-specified CFC shapes
- Defined by azimuth and range limits
- Maximum of 15 shapes
- Can be edited

- APDA products defined on background map
- Manual override, initially

## ORPG Clutter     Filter Control       (CFC) Panel

**ORPG Clutter     Filter Control       (CFC) Panel**
- AP detection products
- will augment this map

## REC in ORPG Build 2

- AP detection algorithm
- installed in ORPG
- build 2 during Sept/Oct
- Accessed through the
- clutter filter control
- Panel
- Two resolutions:
-     Doppler
-     Surveillance
- Example is from
- Denver KFTG

## netCDF files

- Validating implemented AP algorithm
- Requires a common data format
- netCDF
- The netCDF format code exchanged with
- ROC
- NWS Headquarters
- Exchanged a few files with ROC

## Slide 16

## ORPG Builds 5, 6

- Build 5
- REC precipitation detection algorithm
- Build 6
- Reflectivity compensation algorithm
- Automated clutter filtering

## IHOP Deployment

- S-Pol near Beaver, OK from May-June
- Ran REC and ZVW-Compensation during operations
- About 10 days
- Several good cases of AP clutter
- Good rain events
- Collaborated with RAP to run the Configurable, Interactive Data Display (CIDD) program
- Reformatters to convert from DORADE to Mdv format
- Movie loops
- Geographical information on display
- Could access other data sets (GOES, metar, etc)
- Very useful during operations

## REC Improvements at IHOP

- Added clutter velocity field
- Use PID output
- Clutter category used to set radial velocity to zero
- Useful to retain small regions of clutter
- REC algorithms use median radial velocity because S-Pol clutter is non-zero
- Will be used to make new REC algorithm for small clutter regions

## REC Improvements at IHOP

- Continued testing  confidence algorithms
- Confidence can improve the PDA algorithm
- Needs more work

- Reflectivity

- PID

- Radial Velocity

## Sea Clutter Detection Algorithm

- SCDA developed under separate funding
- NCAR/RAP
- Deployed on civilian United Arab Emirates (UAE) Enterprise radars
- 3 radars in network, more are planned
- Membership functions are still being tuned
- AP detection algorithm also deployed
- SCDA is not yet implemented within ATD REC

## Sea Clutter Detection Algorithm

- Feature fields
- 3 variables for vertical variation of reflectivity
- 2 variables for horizontal variation of reflectivity
- Median spectrum width
- Standard deviation of the radial velocity
- Local area or gate-to-gate difference

## UAE

**UAE**
**Radar Data Quality**
- Only APDA and SCDA are deployed

## Spectral Domain Processing

- Thinking about how to combine the REC with spectral domain processing techniques
- New variables will be available
- Ratio of filtered power to total power
- On-the-fly processing with ability to re-process regions with clutter

## Summary

- AP detection algorithm deployed in ORPG
- ORPG clutter filter control panel
- AWIPS (after next build)
- PDA, Z-Comp and automated clutter filter control planned for ORPG Builds 5 and 6
- New REC algorithms
- Sea clutter algorithm
- Convective/stratiform partition
- AP detection for small regions