# Presentation: 748778

## Ceiling and VisibilityWeather Project

- John McCarthy
- Naval Research Laboratory
- NASA AWIN Program
- NASA Langley
- May 24, 2000

## C&V Requirements Abound

## Federal Aviation Administration

** ****Safer Skies:  A Focused Safety Agenda**

**General Aviation**
**Weather Joint Safety Analysis Team**
- Final Report
- April 1999

## Routine IMC– low ceilings or fog, obscurations to visibility, rain, and snow -- were a cause or factor in an overwhelming majority of fatal weather accidents, not only for Part 91 operators

## Navy Pacific Meteorology and Oceanography Center – San Diego

- Commanding Officer (CAPT Gunderson) prepared following statement regarding C&V following Monterey meeting

## The meteorological phenomena that have both the most impact on U.S. navy operations in the Southern California Operating Area, and are the most difficult to forecast, are low stratus and fog...

## NASA Aviation Safety Program Evolution

- Aviation Safety Investment Strategy Team (ASIST)
- White House (Gore) Commission on Safety and Security
- Aviation Safety Program

## Slide 8

## C&V: NAS Issues and Needs

- C&V Impacts on Aviation Safety
- Major factor in GA fatalities
- Contributing factor for many accidents
- C&V Impacts on NAS Delay
- 85% of delay is Wx related
- About Half of this is due to C&V
- Engineering Solutions
- More Runways
- Better Surveillance and Tracking
- Vision Technology
- Improved Information and Decision Aids
- Precision Weather Forecasting
- Operationally significant changes: START & STOP
- Match traffic to actual capacity
- 0 to 4 hour forecasts

**Notes:**

1. Safety is the fundamental issue
   - contributing factor in many transport category accidents
   - leading cause of fatalities or GA
2.  GA solution requires better wx products, comm, & training
(NASA AWIN program deals with the latter two, products will probably come from the AWC through AWRP $$)
3. For transport category, we have traded delay for safety
   - It works! No US crashes with C&V as primary factor in many years
   -IFR and practice lead to major reductions in capacity at congested airports
   - there are pressures to push the envelope
3. Since the weather is benign, we can look to a time when there is a complete engineering solution to the NAS C&V problem.
4.  Until that time, precise Wx forecast can reduce delay by insuring that no VFR opportunity is missed.

## C&V Complexity

- Many meteorological  causes
- Visibility: Fog and heavy precipitation
- Low Ceiling: Marine Stratus, Frontal Stratus, lifting fog
- Radiative cooling and heating
- Extra-tropical Storms (C&V is part of a precipitation event)
- Regional Forcing (Advection)
- There is no single technical break-through that will cure the C&V problem
- Product selection is a balance of factors
- technical risk
- event frequency
- development cost
- leveraging
- aviation benefits
- FAA C&V PDT focus is on Marine Stratus and Winter Storms
- Technology Spin-off to AWC

**Notes:**
1. There is a single  human impact: Reduced Vision
2. But there are many meteorological  causes, which require many solutions. 
3. The NAS priorities may differ from research priorities of other groups

4. Our job is to provide solutions to NAS problems, not just to advance science

## C&V Forecast/Nowcast Improvement Program

## Objectives of C&V Program

- Examine ability of models to adequately describe ceiling and visibility
- Improve moisture physics of mesoscale models (COAMPS, MM5, RUC-II, etc.) with the understanding that such improvements are essentially interchangeable
- Compare mesoscale model C&V output with independent METAR comparison

## Objectives of C&V Program (Cont’d)

- Develop local area capability to provide improved C&V products (initial focus on SOCAL), to support NPMOC-SD, Los Angeles Center CWSU and TMU
- Develop ADDS-oriented C&V product for Aviation Weather Center
- Develop world-wide C&V forecast/nowcast improvement capability

## Objectives of C&V Program (Cont’d)

- Use knowledge-based approach  with multi-sensors/models to develop 0-6 hour nowcast
- Validate scientific skill of products
- Conduct operational demonstrations with users

## Fused Ceiling & Visibility Product

- Model Ceiling & Visibility Product

- Convective Cloud Ht

- Satellite Low Cloud Product

- Radar Product

- Rain Rate

- Obs: METAR, AIREP/PIREP

- Convective Clouds X-S

- Assign Membership Functions and Dynamic Weights

## Forecasts

**Data Fusion for Weather Assessment (DaFWA)**

- NWP Model
-  COAMPS
- Grid
- 81 km (black) 52 x 46
- 27 km (yellow) 61 x 85
- 9 km (red) 58 x 121
- Duration
- Successive 12-hour forecasts
- 6 months
- Forecasted Fields
- Ceiling (unlimited > 9000 m)
- Visibility (unlimited > 16.1 km)

## Stratus

- Cloud Ceiling Height (m)

- Visible Satellite Image (1 km)

## Fronts

- Cloud Ceiling Height (m)

- Visible Satellite Image (1 km)

## High Clouds

- Cloud Ceiling Height (m)

- Visible Satellite Image (1 km)

## Forecasts vs. METAR

- Monterey (KMRY)
- San Luis Obispo (KSBP)
- _Los Angeles (KLAX)_
- Underpredicted low ceilings and low visibilities

- _San Francisco (KSFO)_
- Overpredicted low ceilings and low visibilities

- _Bakersfield (KBFL)_
- Summer - Near Perfect
- Fall - Underpredicted low visibilities

## How close are the “missed” forecasts?

- Consider ceiling as unlimited or restricted
- When the model failed to predict a restricted ceiling height.....
- .....how close was the correct forecast?

## Percentage of closest correct forecasts within the yellow boxes

- _Differences_
- Topography
- Aerosols

## Conclusions

- Qualitative - Good correlation between the ceiling height forecasts and satellite imagery (shape and timing)
- Quantitative - Poor correlation between observations and forecasts until surrounding gridpoints are considered

## CEILING 

- CEILING
- 04/27/00 20Z

## VISIBILITY 

- VISIBILITY
- 04/27/00 20Z

## FLIGHT CAT. 

- FLIGHT CAT.
- 04/27/00 20Z

## Slide 27

## Slide 28

## Fused Ceiling & Visibility Product

- Model Ceiling & Visibility Product

- Convective Cloud Ht

- Satellite Low Cloud Product

- Radar Product

- Rain Rate

- Obs: METAR, AIREP/PIREP

- Convective Clouds X-S

- Assign Membership Functions and Dynamic Weights

## Summary

- C&V Program off to a good start
- NRL and NCAR working well together
- NPMOC-San Diego and AWC/ADDS in background waiting to participate
- Meets an important objective of NASA AvSP
- Three-year funding required to maintain program
- Major East Coast winter storm/C&Vexperiment being considered by FAA, NASA, and others

## Slide 31