# Presentation: 542906

## NEXRAD Machine Intelligent Gust Front Algorithm (MIGFA)Seth Troxel(Presented by J. Evans)Presentation to NEXRAD TAC

**May 28, 2003**

## Outline

**MIGFA overview**** **
**MIGFA enhancements for NEXRAD**** **
**Summary and Status**

## What is MIGFA?

**Machine Intelligent Gust Front Algorithm originally developed for FAA**
**Provides current and future locations of gust fronts and other wind shift boundaries, plus estimates of wind shear and winds behind each front**
**Multi-dimensional image processing approach**
**Fuzzy logic, data fusion, delayed thresholding**** **
**Important component of three operational FAA systems:**
**ASR-9 WSP (presently being deployed)**
**TDWR (replaced previous generation gust front algorithm)**
**Integrated Terminal Weather System (ITWS)**** **
**Used by FAA to improve air safety and runway usage planning**

## Gust Front Detection onSituation Display

## NEXRAD MIGFA Benefits

**NWS**
**Assist in issuing high wind and damaging wind warnings**
**Assist NWS forecasters in anticipating:**
**Surface wind shifts**
**Convergence zones (favored locations of convective initiation)**
**Tornados (strong convergence or GF collision points may be precursors)**
**FAA**
**Gust front warnings for airports without TDWR or WSP**
**Alternative for TDWR or WSP when unavailable or poor data quality (second trip contamination, bad viewing angle)**
**Useful input to other ITWS and CIWS products (Terminal Winds, convective forecasts)**
**Future component of Medium Intensity Airport Weather System (MIAWS)**** **
**Air Force / DOD**
**Avoid damage from straight-line winds**
**Wind shear warnings for DOD aircraft operations**
**Convective weather forecasting**

## Machine Intelligent Gust Front Algorithm (MIGFA)

**Extract**

**Wind Analysis**

**Track**

**Machine Intelligent Gust Front Algorithm (MIGFA)**

**Prior Predictions**

**Feature Detectors**

**Reflectivity**

**Velocity**

**Combine Interest**

**Input**

**Updated**
**History**

**Predictions**

**Detections**

**Output**

**Radar**
**Base Data**

**Event**

**Convergence**

**Anticipation**

**Conv. Motion**

**Anemometer Data (optional)**

**Prior History**

**Thin Lines**

**Combined Interest Image**

**Velocity +****Refl Thin Lines**

**Thin Lines**

**Thin Line Motion**

## NEXRAD MIGFA Challenges

**Need to detect all convergent boundaries, not just strong gust fronts  **
**Important for convective weather forecasting**
**Initial version was too sensitive**
**Too many detections on small, transient convergence features**
**False detections on thin, light rain bands**** **
**Not enough use of valid thin line signatures**
**Compared with TDWR, NEXRAD has more missing velocity data (S/N thresholding, clutter editing).  Velocity convergence signatures may be absent**
**Earlier version failed to detect boundaries lacking convergence signatures in spite of definitive thin line signatures. **** **
**Fragmented detections**
**Some causes: storm cell obscuration, missing data**** **
**Numerous enhancements have been made to address these issues and to create additional products for broad set of users**

## NEXRAD MIGFA Enhancements:Connecting Compatible Segments

** **

**With****Connecting**

** ****Without Connecting**

**Proximate, colinear detection segments having similar propagation attributes are connected**

## NEXRAD MIGFA Enhancements:Better Use of Thin Line Signatures

**Adaptive thin line detection**
**Large averaging kernel used to “normalize” background and increase thin line contrast for improved detectibility**** **
**Extending detections along thin lines**
**Detection lengths may be truncated due to lack of convergence evidence**
**Additional pass of gust front chain extension guided by thin line interest improves detection length**** **
**Interest boosting for long (> 10 km) reflectivity thin lines**
**Some weak boundaries lack velocity convergence signature, yet have long, distinctive reflectivity thin lines**
**Average (consensus) interest image is boosted in regions of very long thin line interest features**

- Without Adaptive Thin Line Detection

- With Adaptive Thin Line Detection

## Improved Use of Thin Line Signatures(movie)

- Without ThinLine Boosting

- With ThinLine Boosting

## NEXRAD MIGFA Enhancements:Dual Tilt Processing

**Previous NEXRAD MIGFA only processed lowest (~0.4 deg) elevation tilt**
**Higher elevation data (~1.5 deg) have far less clutter near radar;  Gust front signatures more visible**
**Reflectivity and velocity data from two tilts are merged to form composites for input to feature detection**** **
**Use of full (uncomposited) low and high tilt data will permit echo altitude discrimination**
**Reduce false alarms from higher altitude rain echoes**

**High Tilt Data**

**Transition**

**Low Tilt Data**

**Range (km)  =>**

**19**

**25**

**0**

**105**

## Improved NEXRAD Gust Front Detection Using Higher Elevation Tilt Data (movie)

**Reflectivity**

**Velocity**

**0.4****o**** Tilt**

**1.5****o**** Tilt**

## Additional NEXRAD MIGFA Outputs

**Confidence attributes will be output with each NEXRAD MIGFA gust front report:**
**Strength (delta-V)**
**Length (km)**
**Tracking depth (# scans gust front has been tracked)**
**Confidence index**** **
**Attributes can be used by clients to choose detections of interest **
**NWS:   All boundaries regardless of strength (e.g., for convective weather forecasting, tornadogenesis)**
**FAA:  High confidence, operationally significant wind shifts for airport planning and safety**** **
**Intermediate images (optional)**
**Interest images, shear images, sweep maps of prior and extrapolated gust front positions**
**Useful for data fusion and analysis in other algorithms (e.g., GFMosaic, RCWF)**

## Gust Front Sweep Map

**‘****Sweep Map’ of a gust front refers to the area swept out over time by a given gust front.  Similar to an interest image.**
**Sweep map contains scores.  Initial score based on the time at which a front will impact (or impacted) a particular location**
**Can increase or decrease this raw score based on the confidence of the detection**
**Can greatly increase this score when gust fronts are colliding**
**Must be sure not to assign high scores for uninteresting collisions (I.e. one front merely ‘chasing’ another)**

**Collision Example**

**Overrun Example**

**High score in****collision zone**

## Activities and Plans Leading to Build 6

**Initial version I/O modifications finalized**
**Field sites being prepped for ORPG MIGFA testing**
**6 ORPG clones at 4 Lincoln Laboratory ITWS prototype field sites**
**2 ORPG clones at Lincoln Laboratory running “dry environment” MIGFA testing in support of ASR-9 WSP**
**Case playback capability at Lincoln Laboratory**
**Analysis of performance**
**Resources**
**With other algorithms**
**Determine if DQA algorithm input can be used**
**Develop FAA-tuned output for use in MIAWS**
**December 2003 transition of MIGFA to the ROC**
**Support ROC integration leading to Build 6 deployment**

## Future Build ORPG MIGFA Products

**NWS-tuned output – Projected Build 7**
**Level of confidence information**
**Gust front forecasts – Projected Build 7**
**10 and 20 minute forecasts**
**On FAA and NWS results**
**Intermediate interest field output – Beyond Build 7**
**Convergence boundaries, shear zones, etc.**
**FAA ASR-9 WSP support**
**NWS convective forecasting support**

## Summary and Status

**NEXRAD gust front product will provide significant benefits to existing and planned FAA, NWS, and DOD systems**
**Fusion with gust front products from other radars**
**Support convective weather forecasting**** **
**Numerous enhancements to MIGFA have been made to optimize performance on NEXRAD**
**NEXRAD MIGFA currently running on 25 radars in Corridor Integrated Weather System (CIWS)**
**Gust front sweep maps input to convective weather forecast product**
**Analysis of results are folded into ongoing improvements.**** **
**ORPG port nearly complete**
**NEXRAD MIGFA in ORPG to be tested at 4 Lincoln ITWS test sites**
**Experience will minimize risk for actual NEXRAD installation**