Attachment F - NOAA Radar Surveillance Requirements Weather.pdf

Date: January 7, 2022

NOAA Radar Surveillance Requirements:

Weather

Products and Services Reflect Weather Phenomena and Rely on Basic Atmospheric Data

• NWS conducts remote sensing of the atmosphere to identify, quantify, and track the movement of weather phenomena and other detected hazards

– Primary phenomena include Precipitation, Tornados, Hail, Fronts/Fine

Lines, Freezing & Melting Regions, etc. Other hazards include Wildfire and Volcanic Ash plumes.

– The atmosphere is sampled over the geographic coverage volume where the NWS has forecast responsibility, and at a spatial scale (i.e., sample volume) and update rate that will resolve these atmospheric phenomena.

– The targets detected in each sample volume of the atmosphere are characterized by type, intensity, and motion.

Mission Needs: NOAA Weather

Example Phenomena: Precipitation Complexity

Hydrometeor / Air Motion Tracer Classification Target Type Attributes Hydrometeors Average Diameter Number Concentration

(targets per m3) Rain 0.5 mm 1150

Heavy Rain 1 mm 56800 Big Drops 3 mm 8

Small Hail 12 mm 0.2

Large Hail 30 mm 8x10-4

Giant Hail (up to 10 cm) 50 mm 4x10-5

Graupel 3 mm 80 Ice Pellets 3 mm 0.8

Snow Flakes 4 mm 0.004 Melting Snow 8 mm 0.02

Cloud Ice Crystals 1 mm 60

Air Motion Tracers Diameter / Cross Section

Number Concentration (targets/m3), except where noted

Tornado Debris

Insects < 1 cm2 1x10-5 - 3x10-4, by altitude, with greater concentrations near ground-level

Chaff 0.24-1.5 mm2 (0.03 mm width x 8-50 mm long) 0.00424 Wildfire Smoke Plumes 0.1-0.15 µm Mass concentration: 50-100 µg/m3 (rural) Volcanic Ash Plumes 0.06-2 mm Mass concentration: 0.2-0.6 g/m3

Ground-Based Objects (filtered for identifying targets above)

Vegetation Man-made Objects

Terrain & Sea

Target Classification via Dual-Pol Variables

• NWS Forecasters interpret targets derived using a number of Dual-Polarization characteristics to verify or correct system determination

• Example below from NWS Training Center used to train forecasters on making correct interpretation using combined characteristics derived from Dual-Pol radar

Current vs. Threshold vs. Objective

• Current – Present operational capabilities

• Threshold - Expected operational capabilities in 2030 due to currently programmed activities such as Service Life Extension Program, Tech Refresh, Product Improvement programs

– Improved accuracy and precision from improved calibration, radar variable estimators, clutter filtering (ground, sea, wind turbine), and Quantitative Precipitation Estimates (QPE)

• Objective - Beyond planned improvements, that are currently NOAA-validated observing requirements (overseen by the NOAA Observing Systems Council – NOSC)

– Address coverage, improve spatial resolution

– Faster update rates (e.g., 60 second volume scans)

NOAA Radar Surveillance Current Capability

Surveillance: Targets - NOAA/Weather Current

Description Distributed Hydrometeors * Distributed Air Motion Tracers (Clear Air Mode) *

Sensitivity (Reflectivity at 50 km) -9.5 dBZ -18.5 dBZ

Velocity Range ±124 kts ±124 kts

Velocity Resolution 1 kt 1 kt

Reflectivity (Z) ** 1 / 1 dBz 1 / 1 dBz

Radial Velocity (V) ** 0.0 / 1 m/s 0.0 / 1 m/s

Spectrum Width (W) ** 0.2 / 0.5 m/s 0.2 / 0.5 m/s

Differential Reflectivity (Zdr) ** 0.2 / 0.4 dB 0.2 / 0.4 dB

Correlation Coefficient (ρhv) ** 0.006 / 0.006 0.006 / 0.006

Differential Phase (ΦDP) ** 1.3 / 2.5 deg 1.3 / 2.5 deg

Comments * Refer to list of hydrometeors / air motion tracers for attributes (cross-section & concentrations) and functional performance.

** Additional Base Data Accuracy (Bias) & Precision (Std) Requirements (Dual-Pol Capabilities)

* Refer to list of hydrometeors / air motion tracers for attributes (cross-section & concentrations) and functional performance.

** Additional Base Data Accuracy (Bias) & Precision (Std) Requirements (Dual-Pol Capabilities)

Surveillance: Targets - NOAA/Weather Current Target Type Attributes Current Performance

Hydrometeors Average Diameter Number Concentration (targets per m3) Probability of Detection Automated

Discrimination Rain 0.5 mm 1000 90% 95%

Heavy Rain 1 mm 57000 100% 90% Big Drops 3 mm 0.2 90% 75% Small Hail 12 mm 6x10-2 100% 90% Large Hail 25 mm 7x10-4 100% 90%

Giant Hail (up to 10 cm) 51 mm 1x10-5 100% 90% Graupel 1 mm 17000 90% 90%

Ice Pellets 1 mm 12000 90% 0% Snow Flakes 2 mm 1000 85% 80% Melting Snow 4 mm 25 90% 80%

Cloud Ice Crystals 0.5 mm 75000 70% 80%

Air Motion Tracers Diameter / Cross Section

Number Concentration (targets/m3), except where noted Probability of Detection Automated

Discrimination

Tornado Debris 90% 0%

Insects < 1 cm2 1x10-5 - 3x10-4, by altitude, with greater concentrations near ground-level

90% 70%

Chaff 0.24-1.5 mm2 (0.03 mm width x 8-50 mm long) 0.00424 90% 0%

Wildfire Smoke Plumes 0.1-0.15 µm Mass concentration:

50-100 µg/m3 (rural) 90% 0%

Volcanic Ash Plumes 0.06-2 mm Mass concentration:

0.2-0.6 g/m3 70% 0%

Ground-Based Objects (filtered for identifying targets above) Probability of Detection Automated

Discrimination Vegetation 90% 70%

Man-made Objects 90% 70% Terrain & Sea 90% 0%

NOAA Surveillance Current Capability:

Targets and Performance

For each sample volume, the NOAA meets the following requirements:

• Probability of detection of hydrometeors: >90% for 0.05 g/m3 liquid water equivalent

• Estimation of average hydrometeor liquid water equivalent content (accuracy above minimum detected level)

– Estimation of hydrometeor liquid water equivalent: ± 0.01 g/m3

• Estimation of motion direction and speed for hydrometeors and other targets

– Wind speed accuracy: 1-3 m/sec depending on strength of radar returns

– Wind direction accuracy: radial motion only, angle pointing accuracy of

0.2 degrees

NOAA Surveillance Current Capability:

Where and How Often

• Areas covered today by existing NEXRAD network

▪ CONUS & OCONUS

▪ Includes FAA and DOD NEXRAD network site coverage

▪ See maps on following slides

• Spatial resolution and altitude coverage (above ground level):

Distance from Radar 2 km 50 km 100 km 200 km 300 km

Spatial Resolution (volume) 2x10-4 km3 0.095 km3 0.381 km3 1.523 km3 3.427 km3

Minimum Beam Elevation 0.018 km 0.60 km 1.53 km 4.37 km 8.51 km

Maximum Beam Elevation 0.65 km 16.5 km 21+ km 21+ km 21+ km

• Sampling update rate:

▪ Severe storms: 90 seconds at lowest levels

▪ General precipitation: 4 minutes for entire coverage volume

▪ No precipitation: 10 minutes for entire coverage volume

NOAA Current Capability – CONUS Coverage

3,000 feet above ground 6,000 feet above ground

10,000 feet above ground

•Puerto Rico

NOAA Current Capability – OCONUS Coverage

NOAA Radar Surveillance Threshold Requirements

Surveillance: Targets - NOAA/Weather Threshold

Description Distributed Hydrometeors * Distributed Air Motion Tracers (Clear Air Mode) *

Sensitivity (Reflectivity at 50 km) -9.5 dBZ -18.5 dBZ

Velocity Range ±124 kts ±124 kts

Velocity Resolution 1 kt 1 kt

Reflectivity (Z) ** 1 / 1 dBz 1 / 1 dBz

Radial Velocity (V) ** 0.0 / 1 m/s 0.0 / 1 m/s

Spectrum Width (W) ** 0.2 / 0.5 m/s 0.2 / 0.5 m/s

Differential Reflectivity (Zdr) ** 0.2 / 0.4 dB 0.2 / 0.4 dB

Correlation Coefficient (ρhv) ** 0.006 / 0.006 0.006 / 0.006

Differential Phase (ΦDP) ** 1.3 / 2.5 deg 1.3 / 2.5 deg

Comments * Refer to list of hydrometeors / air motion tracers for attributes (cross-section & concentrations) and functional performance.

** Additional Base Data Accuracy (Bias) & Precision (Std) Requirements (Dual-Pol Capabilities)

* Refer to list of hydrometeors / air motion tracers for attributes (cross-section & concentrations) and functional performance.

** Additional Base Data Accuracy (Bias) & Precision (Std) Requirements (Dual-Pol Capabilities)

Surveillance: Targets - NOAA/Weather Threshold Target Type Attributes Threshold Performance

Hydrometeors Average Diameter Number Concentration (targets per m3) Probability of Detection Automated

Discrimination Rain 0.5 mm 1000 90% 95%

Heavy Rain 1 mm 57000 100% 90% Big Drops 3 mm 0.2 90% 75% Small Hail 12 mm 6x10-2 100% 90% Large Hail 25 mm 7x10-4 100% 90%

Giant Hail (up to 10 cm) 51 mm 1x10-5 100% 90% Graupel 1 mm 17000 90% 90%

Ice Pellets 1 mm 12000 90% 0% Snow Flakes 2 mm 1000 85% 80% Melting Snow 4 mm 25 90% 80%

Cloud Ice Crystals 0.5 mm 75000 70% 80%

Air Motion Tracers Diameter / Cross Section

Number Concentration (targets/m3), except where noted Probability of Detection Automated

Discrimination

Tornado Debris 90% 95%

Insects < 1 cm2 1x10-5 - 3x10-4, by altitude, with greater concentrations near ground-level

90% 90%

Chaff 0.24-1.5 mm2 (0.03 mm width x 8-50 mm long) 0.00424 90% 90%

Wildfire Smoke Plumes 0.1-0.15 µm Mass concentration:

50-100 µg/m3 (rural) 90% 0%

Volcanic Ash Plumes 0.06-2 mm Mass concentration:

0.2-0.6 g/m3 70% 0%

Ground-Based Objects (filtered for identifying targets above) Probability of Detection Automated

Discrimination Vegetation 90% 70%

Man-made Objects 90% 70% Terrain & Sea 90% 0%

Note: shaded cells represent change in requirement from Current to Threshold

For each sample volume, the NWS requires:

• Probability of detection of hydrometeors

– >90% for 0.04 g/m3 liquid water equivalent

– Estimation of average hydrometeor liquid water equivalent content (accuracy above minimum detected level)

– Estimation of hydrometeor liquid water equivalent: ± 0.01 g/m3

• Estimation of motion direction and speed for hydrometeors and other targets

– Wind speed accuracy: 0.5 m/s

– Wind direction accuracy: 1 degree horizontal

Surveillance: Targets NOAA/Weather Threshold

Note: highlighted text represent change in requirement from Current to Threshold

Surveillance: Requirements NOAA/Weather Threshold

Label Clear Air Precipitation Severe Wx – Low Altitude

Operational Availability

0.96 0.96 0.96

Accuracy (x, y, z) 130 x 37 x 130 m 130 x 37 x 130 m 65 x 37 x 65 m

Resolution (x, y, z) 872 x 250 x 872 m 872 x 250 x 872 m 436 x 250 x 436 m

Update Rate (volumetric)

10 min 4 min 90 sec

Data Latency 2 sec 2 sec 2 sec

Interface NOAA WSR-88D National Level II Interface Control Document (WSR-88D Document Number 2620002, Build 17.0)

NOAA WSR-88D

National Level II Interface Control Document

NOAA WSR-88D National Level II Interface Control Document

Note that the accuracy and resolution are based on the current capability at 50 km from the NEXRAD.

QUESTIONS?