# Presentation: 433626

## Mosaicking to Improve Gust Front Detection and Forecasting

**Justin D. Shaw**
**MIT Lincoln Laboratory – Weather Sensing**
**28 May 2003**

## Outline

**Introduction**
**Background**
**Motivation**
**Gust Front Mosaic Strategy**
**MIGFA Interest images**
**Mosaic Algorithm Development Strategy**
**Performance**
**Summary**

## Motivation

**Terminal ATC safety enhancement and delay reduction**
**wind shear alerts based on detections/extrapolated positions**
**wind shift forecasting**
**Convective weather forecasting**
**boundary intersections – triggering mechanisms**
**Tornado forecasting**

## Importance of Multiple RadarGust Front Detection and Integration

**Many terminal areas (e.g., DFW, NY, Chicago, Miami, Washington) have overlapping radar coverage at low altitudes**
**Machine Intelligent Gust Front Algorithm (MIGFA) currently operating on TDWR, ITWS, ASR-9 WSP and will be used on NEXRAD shortly**** **
**DFW experience shows detection and tracking of gust fronts****can be significantly improved by integrating gust front information from multiple radars**** **
**Gust Front TRACON Map (GFTMAP) is current gust front mosaic algorithm for ITWS:**
**Utilizes a-priori rule grid to select which radar’s gust front product output is to be displayed at each location**
**“****Slice and dice” product-based approach**
**Poor performance noted.  May select “wrong” radar for given gust front geometry**** **
**New Gust Front Mosaic (GFMosaic) algorithm utilizes MIGFA-like evidence fusion approach**

## Boundary Layer Winds Coverage

**A** **= ASOS Stations**

## ITWS Gust Front Product

## DFW Gust Front Detection Challenge

**DFW Gust Front Detection Challenge**

**DFW Gust Front Categorization (1999-2002)**

**March 25, 2002**

**Doppler velocity convergence signature vanishes as front becomes radially aligned**
**High percentage of gust fronts at DFW have NE-SW orientation**
**DFW radar has poor viewing angle**

## MIGFA Detection Comparison

**DFW TDWR Velocity & MIGFA Detections**

**DAL TDWR Velocity & MIGFA Detections**

**Improved gust front detection over DFW when using data from DAL TDWR**

## MIGFA Gust Front Extraction Approach

**DAL TDWR Velocity**

**DAL TDWR Reflectivity**

**MIGFA Combined Interest**

**MIGFA Detections**

**Gust fronts are extracted from regions of high interest**

**Combined interest image represents consensus of pattern matching evidence**

## GFMosaic Processing Approach

**GFMosaic Processing Approach**

**MIGFA #1**

- Track

**MIGFA #2**

**Interest**

**Preferred inputs: Intermediate data from operating****MIGFAs (interest, shear, velocity images)**
**Alternative inputs: Images may be fabricated from final MIGFA detection product data**
**Fused evidence may be stronger than individual interest => better detection potential than individual MIGFAs**
**Gust fronts are re-extracted and tracked from fused evidence using MIGFA library routines (software re-use)**
**Optional input of ITWS Terminal Winds product for improved gust front wind analysis**

**Interest Mosaic**

**Interest**

- GFDetections,Predictions

**GFMosaic**

## NEXRAD MIGFA Interest Map

**Interest map generated from NEXRAD MIGFA can be merged with TDWR MIGFA interest**

**NEXRAD Reflectivity**

**NEXRAD Velocity**

**NEXRAD Interest Map**

## DFW Gust Front Mosaic Performance Statistics

**Intermediate data-level fusion by GFMosaic shows improved POD compared to MIGFA **
**Work continues to reduce PFA for GFMosaic**

## Comparison of NEXRAD and TDWR MIGFA

**17 July 1995**

**NEXRAD**

**TDWR**

**NEXRAD MIGFA performs as well as TDWR MIGFA on this case**

**NEXRAD**

**TDWR**

**TDWR**

**NEXRAD**

## Comparison of NEXRAD and TDWR MIGFA

**17 August 1995**

**MIGFA does excellent job**
**detecting full ring gustfront**
**estimating winds behind gustfront**
**NEXRAD clutter prevents detection of solid convergence signature**

**NEXRAD**

**TDWR**

## Comparison of NEXRAD and TDWR MIGFA

**19 August 1995**

**MIGFA detects gustfront well even with vague and noisy data signatures**
**TDWR misses part due to second trip contamination**
**Combination of radars would achieve better detection**

**Comparison of NEXRAD and TDWR MIGFA**

**NEXRAD**

**TDWR**

## MEM GF CASE (NEXRAD vs. TDWR)

**16 May 2003**

**Range folding obscures GF in TDWR data over airport**

## Proposed Use of NEXRAD to AugmentASR-9 WSP Gust Front Detection

**25**

**50**

** ****ASR-9 has difficulty detecting weak gust ****  front signatures, especially in dry   **
**  ****environments**
** ****NEXRAD gust front product could be ****  integrated with WSP detections to improve****  performance**

**ABQ ASR-9 WSP**

**KABX NEXRAD**

**Gust fronts**

**ASR-9**

**Clutter**

**July 17, 1999  01:27:47 GMT**

## Summary

**Many large TRACONS have overlapping radar coverage, including NEXRAD**** **
**Radial alignment of gust fronts with respect to single radar can cause significant detection degradation**
**Gust front detection is improved by utilizing data from additional radars having different viewing angles**** **
**New GFMosaic algorithm effectively fuses intermediate gust front evidence maps from operational gust front algorithms (MIGFAs)**
**Testing ongoing at DFW.   Summer, 2003 tests targeted for  NY ITWS site**** **
**NEXRAD gust front coverage will likely provide significant performance benefit for several FAA systems (ITWS, ****ASR-9 WSP, MIAWS)**