# Presentation: 277748

## NEXRAD Product Improvement

**NEXRAD Product Improvement**
**Dual Polarization**
**Decision Brief**
**Greg Cate**
**W/OST11**
**NEXRAD Program Management Committee**
**November 2003**

**Notes:**
This is a status briefing on the Open Radar Product Generator (ORPG) Project.

## Agenda

- Scope of Effort
- Economic Benefit
- Operational Benefit
- Estimated Cost
- Acquisition Strategy Outline
- Tentative Schedule
- Recommendation

## Scope Of Effort

- NPI Program Tasked NSSL To
- Collect Additional Data Using KOUN during Spring 2003
- Analyze The New and Previously Collected Data
- Conduct An Operational Demonstration
- Perform An Engineering Analysis
- NSSL Consulted with ROC and OS&T Subject-Matter-Experts on Results
- Results documented in NSSL Reports
- NPI Develop :
- Cost and Schedule Estimates
- Acquisition Strategy Outline

## Economic Benefit Analysis

- Utilized “NEXRAD Technical Requirements for Precipitation Estimation and Accompanying Economic Benefits” (Hudlow, et.al., 1985)
- Report related flash flood damage avoidance & water management to accuracy of precip estimates
- Dual Pol Improves precip estimation accuracy from 30% to (approximately) 12.5%. (Zrnic, 2003)
- Applying The Hudlow Approach Resulted In
- Estimated annual benefit - $690M
- Analysis Supported by NSSL; Validated by Dale Sirmans

## Accuracy Improvement Benefit

- 0

- 10

- 20

- 30

- 40

- 50

- 60

- 70

- 80

- 90

- 100

- 0

- 276

- 552

- 828

- 1104

- 1380

- 1656

- 1932

- 2208

- Accuracy

- Hydrologic benefits (in million $)

- Benefits from full implementation of

- pre WSR-88D capability

- Current Benefits (2003)

- Accelerated loss in benefits from increasing error

- in inputs and runoff model magnification

- Benefits from full implementation of polarimetric capability

- 1834

- 1144

- 414

## Operational Benefits

- Data Quality Improvement
- Rainfall Estimation Improvement
- Hail Detection Improvement
- Rain/Snow Discrimination
- Future – Tornado Signature

## Improvement in data quality

- Composite plot of Z, ZDR,ρhv, and results of classification at El = 0.5° on 24 August 2002, 0734 UTC.
- 	AP – ground clutter / anomalous propagation
- 	BS – biological scatterers
- 	RA - rain

-  Polarimetric classification algorithm _identifies and filters out about 99% of non-meteorological echo_ if signal-to-noise ratio exceeds 10 dB
-  Polarimetric radar substantial reduces  biases of radar reflectivity factor due to radar _calibration errors_, _partial beam_ _blockage_, and _attenuation_ in heavy rain and hail.
-  The _quality of Doppler wind measurements_ in clear air will be improved using unique capability of the polarimetric radar to discriminate between passive tracers of wind and turbulence in clear atmosphere (mostly insects) and the scatterers that contaminate the retrieved wind profiles (mostly birds)

- INSECTS

- BIRDS

## Polarimetric rainfall estimation

- Spring hail cases

- Cold season stratiform rain

-  JPOLE Data
-  108 Oklahoma Mesonet and 42 ARS Micronet gages
-  24 rain events (50 hours of observations) .
-  Results
- Polarimetric rainfall algorithm _RMS error of 1-hour accumulation reduced_ by factor of: 1.8 for point and 3.7 for areal rainfall estimates with respect to legacy algorithm.
-  Most significant improvement achieved in areal rainfall estimation and in heavy precipitation (often mixed with hail).
-  Polarimetric method _less affected_ by radar _calibration errors,_ _beam blockage_, _attenuation,_ _drop size distribution variations_, and _presence of hail_ than the conventional method.

- Hourly gage accumulations versus their estimates obtained with conventional and polarimetric algorithms.

- The bias in areal rain rates estimated from radar using conventional and polarimetric algorithms

## Polarimetric Hail Detection

**2003 Storm Intercept Verification**
- Provided more accurate verification data (hail/no hail) for 60 storms
**Hail Detection Statistics**
**Conventional**  **                 POD=88%  FAR=39%  CSI=0.56**
**Polarimetric** **                    POD=94%  FAR=8%    CSI=0.86**
**Method of Detection**
**Conventional:**  Hail probability founded on physically-based _empirical_ relationships
**Polarimetric:**  Classification of hail founded on _measured_ polarimetric characteristics of hydrometeors
**Location of Hail**
**Conventional:**  Probability of hail applies to _any_ location within a storm cell depicted by the SCIT algorithm
**Polarimetric:**  _Specific location_ of hail within the storm cell is identified

- Note: Currently no hail size discrimination performed by polarimetric algorithm

## Discrimination between rain and snow

**Rain**

**Freezing rain**

**Snow**

- Delineation between rain (orange) and snow (green) at the 0.5° PPI radar scan in the case of freezing rain on 4 December 2002 (0302 UTC). Numbers indicate surface temperatures (F°).

-  Polarimetric classification algorithm allows _detection of bright band_ and _delineation of rain and snow_
-  _Freezing rain can be identified_ if polarimetric data are used in combination with surface temperatures
-  Discrimination between rain and snow at the lowest elevation scan is necessary to correctly estimate amounts of precipitation (liquid or frozen)
- Can A statement about icing identification for aircraft operations be made?

## Dual Polarization Tornado Signature

- _Description_: Radar Return from Tornado Debris
- _Utility_: Help with Tornado Warnings
- 	Prevent missed tornadoes
- 	Accurate Severe Weather Updates, pinpoint 	tornado location
- _Limitations_: Not Seen with All Tornadoes
- 	Seen with strong (F3) & violent (F4) tornadoes
- 	Seen with only a few weak (F0/F1) tornadoes
- 	Max detection range not yet known
- _Further Work_: More Data Collection/Analysis
- 	Need more data to define max detection range
- 	Need to find wind strength for debris lofting
- 	Need more data for tornadic bow echoes
- 	_Tornado precursor signature may exist within developing hook echo precip distribution_: more data collection/analysis needed

## JPOLE Experiment Operator Evaluation Of Dual Polarization Impact

- Norman WFO Forecasters Provided KOUN Dual Pole Data During April-June 2003 (480 hours)
- Surveys of KTLX Operators Utilizing Dual Pol Data as Augmentation (Schuur, et.al., September 2003)
- Seven Post-shift evaluations after warning Operations
- All agreed or strongly agreed Dual Pol data were positive contribution to improving forecast and/or warning performance
- Six End-of-season evaluations rating usefulness (Scale 1-5; 5 most positive)
- Overall score  - 4.33

## Rainfall Comparisons with the Oklahoma Mesonet

**J O I N T     P O L A R I Z A T I O N     E X P E R I M E N T**

- “I used the KDP estimates in far southeastern Oklahoma to assess where heavy rain fell the previous night and on the morning of the 19th.  The data matched the Mesonet so well it wasn’t necessary to make any significant subjective adjustments, unlike the ZR products which significantly overestimated amounts.  By using KDP, I had greater confidence that flooding was not a serious problem and that it was “safe” to spend more time monitoring and updating our aviation and public forecast products.”

**David Andra**
**Science and Operations Officer**
**National Weather Service Forecast Office**
**Norman, OK**

## NWSFO Area Forecast Discussion Product Disseminated Saturday June 14, 2003

- AREA FORECAST DISCUSSION
- NATIONAL WEATHER SERVICE NORMAN OKLAHOMA
- 940 PM CDT **SAT JUN 14 2003**
- MAIN CONCERN THIS EVENING HAS BEEN WATER PROBLEMS...WITH VERY HIGH RAINFALL RATES AND SLOW MOVEMENT. **KTLX/KFDR/KVNX RADARS HAVE BEEN ABOUT OBS+150% WITH RAINFALL ESTIMATES.  DUAL_POLARIZATION KOUN RADAR MUCH...MUCH BETTER.**

## NWSFO Warning Decision Update Product Disseminated Thursday May 8, 2003

- WARNING DECISION UPDATE
- NATIONAL WEATHER SERVICE NORMAN OK
- 345 PM CDT **THU MAY 8 2003**
- THIS WARNING DECISION UPDATE CONCERNS SOUTHWEST AND CENTRAL OKLAHOMA.
- NORTHEAST COMANCHE COUNTY STORM IS STRENGTHENING AND **POLARIMENTRIC RADAR DATA (ZDR) FROM NSSL SUGGESTS LIQUID WATER ABOVE FREEZING LEVEL INDICATIVE OF STRENGTHENING UPDRAFT.**  NOW LOOKING CAREFULLY FOR COLUMN OF HIGH Z (>50 DBZ) BETWEEN 15_30 KFT.  THIS MAY BE AN INCIPIENT SUPERCELL.

## Heavy Snow Event of 24-25 February 2003

**J O I N T     P O L A R I Z A T I O N     E X P E R I M E N T**

- Initial NWS Forecast
- Atmospheric conditions and polarization data supported the issuance of a **Winter Weather Advisory** at **2130 UTC** calling for 2 inches of snow and sleet.  Early phone calls to spotters confirmed snow/sleet mix w/light accumulations
- Winter Storm Evolves Rapidly
- Shortly after initial advisory, significant changes in characteristics of polarimetric data were noted that aided NWS forecasters in assessing the rapidly changing situation.  Polarimetric data suggested precip type had changed to snow.  Calls to spotters confirmed. This information coupled with other meteorological information lead to the issuance of a **Heavy Snow Warning** at **2355 UTC**.

## Heavy Snow Event of 24-25 February 2003

**J O I N T     P O L A R I Z A T I O N     E X P E R I M E N T**

**URGENT - WINTER WEATHER MESSAGE**
**NATIONAL WEATHER SERVICE NORMAN OK**
**555 PM CST MON FEB 24 2003**
**OKZ041-043-046>048-050>052-250550-**
**ATOKA OK-BRYAN OK-CARTER OK-COAL OK-JOHNSTON OK-LOVE OK-MARSHALL OK- MURRAY OK-**
**INCLUDING THE CITIES OF...ARDMORE AND DURANT**
**...HEAVY SNOW WARNING THIS EVENING...**
**SNOWFALL...SOMETIMES HEAVY...IS EXPECTED TO ****ACCUMULATE 4 TO 6 INCHES BEFORE MIDNIGHT.**** PERIODS OF HEAVY SNOW WILL REDUCE VISIBILITY SIGNIFICANTLY. ACCUMULATIONS OF HEAVY SNOW IN THE WARNING AREA WILL CAUSE HAZARDOUS DRIVING CONDITIONS. USE EXTREME CAUTION IF TRAVEL PLANS CANNOT BE POSTPONED.**

**Successful Heavy Snow Warning – *****“Polarimetric Radar Data significantly increased forecast confidence and likely contributed to several hours additional lead time.”****** ***
***– ******Dan Miller, NWS Norman Forecaster***

## Summary Of Expected Dual Polarization Benefits To Operations

- NWS GPRA Goals
- Subjective Estimates Of Dual Pole Impact On Warning Performance ( H – High, M – Medium, L – Low, NC – No Change)

| Warning Phenomena | Prob. Of Detection | False Alarm Rate | Lead Time |
| --- | --- | --- | --- |
| Tornadoes | Promising, impact TBD | Promising, impact TBD | Promising, impact TBD |
| Severe Weather
(Hail) | H | H | M |
| Flash Floods | H | H | M |
| Winter Weather | H | H | H |

## Summary Of Expected Dual Polarization Benefits To Operations(Continued)

- Additional Benefits To NEXRAD Agency Operations And National Economy
- Subjective Estimates Of Dual Pole Impact   (H – High, M – Medium, L – Low, NC – No Change)

| Phenomena | Impact | Application |
| --- | --- | --- |
| Data Quality | H | FAA ATC Systems, Wind Input For NWP, Clean Input Data For Radar Algorithms, Increased Storm Detection In Partially Blocked Areas & Due To Attenuation |
| Precipitation Estimation | H | River Forecasts, Water Management, Agriculture & Forecast Management, Snow Removal Management, Flash Flood Warnings |
| Hail Detection | M | Agriculture Management, Air Traffic Safety, Resource (e.g., Aircraft, Personnel) Protection |
| Rain/Snow Discrimination | H | Air Traffic Safety, Highway Safety, Power Grid Management, Snow Removal Management, Agriculture & Forest Management |

## ROM Schedule & Costs

**Rough Order of Magnitude funding requirements **
**Requirements Analysis, Development and Testing(FY04 – FY07)**
**$6.5M**
**Procurement (FY06 – FY08)**
**$26M**
**$125K/site**
** ****15% spares**
**Deployment (FY07 – FY09)**
**$4.5M**

**Agency funding:**
**- Fund per Agency Cost-share MOA**
**- DOC and DOD funding adequate**
**- FAA: Needs program requirements to be defined**

## Acquisition Strategy Outline

- Develop Performance Requirements
- Leverage NSSL Experience
- Include ROC and Agency Stakeholders
- Continue Emphasis on Commercial Solutions
- ORDA SIGMET Supports Dual Pol Modification
- With Requirements as Driver, Contract for –
- Development
- Production
- Deployment
- Utilize NSSL work in Dual Pol Algorithm Development
- Align with Current NEXRAD Maintenance Concept
- Administer in OS&T/NPI

## Schedule

- Phase 1  – FY04
- Requirements Definition
- Program Plan/Acquisition Plan Completed
- Develop Statement of Objectives for Contract
- Phase 2 – FY05-07
- Design/Development
- Test
- Phase 3  – FY07-09
- Production
- Deployment
*NPI Project Lead will obtain NPMC approval-to-proceed at key Program milestones*

## Summary of Results

- JPOLE and Follow-on Analysis of Dual Polarization Results Demonstrate Significant Improvements (as documented in NSSL reports):
- Data Quality
- Rainfall Estimation
- Hail Detection
- Rain/Snow Discrimination
- Contribution to NWS GPRA Goals for Flash Flood, Winter Storm Warning, Tornado Warning
- Contribution to NEXRAD Agency Operations And National Economy
-  Annual Benefit from Improved Flash Flood Warning and Water Management- $690M
- National Research Council and TAC Support Dual Polarization

## Recommendation

- NEXRAD NPMC approve commencing Phase 1 of the Dual Polarization project under the NEXRAD Product Improvement program

## Supporting Documentation