GOES Aviation Products in AWIPS

February 2007

Short-term Prediction Research and Transition (SPoRT)Center Training Module

Research to Operations -- NASA and Southern Region weather forecast offices

• testbed for new products to operations

• training modules and science sharing sessions

• product assessments of impact

Focus• NASA EOS satellite observations

• modeling and data assimilation

• nowcasting and lightning

Collaborative Research Area

Mission: Apply NASA measurement systems and unique Earth science research to improve the accuracy of short-term (0-24 hr) weather prediction at the regional and local scale

NASA’s SPoRT Center

Objective: Describe the NESDIS GOES aviation “research” products available in AWIPS in advance of their operational implementation.

Outline:• Motivation

• Product description

• Examples

• References and links

GOES Aviation Products in AWIPS

• Products require thorough testing before dissemination via AWIPS

• In a “testbed” mode, products can be made available ahead of time

• This allows the forecasters to evaluate the products

This testbed approach provides advanced exposure and training to the forecaster.

This training module will: describe the experimental aviation products available to

selected offices in AWIPS describe how to access and interpret them in AWIPS

Motivation

• Products are available hourly

• Cloud and fog properties can be descriminated

• Additional information from these products help the forecaster’s awareness of the current environment and can also be used when producing TAFs

• In the future, these products will be widely disseminated to all WFOs

Benefit of Products to Forecasters

These experimental products are produced hourly by NESDIS from the Imager or Sounder on the GOES-12 satellite at 4 km resolution.

The four GOES aviation products, developed by Gary Ellrod of NESDIS, are:

• icing – mask of region where aircraft icing may occur

• icing height – maximum height of icing above surface

• fog depth – thickness or depth of fog

• low cloud base – height of cloud base above ground surface

GOES Aviation Products

Access to Aviation Products in AWIPS

Aviation products in D2D:

• access through the Satellite menu

• default enhancement curves

• correspond to office projections at 4 km

• data available hourly

Aircraft Icing

Icing Mask and Height

Basic criteria for aircraft icing:• liquid phase clouds with temperatures in the 0 to -25 °C range

• large droplet diameters (> 50 μm)

• upward motion to replenish the available supercooled water

• large liquid water contents

• long exposure to icing conditions during flight

GOES satellite data can be used to estimate:• cloud phase

• cloud top temperature

• cloud drop size and liquid water content

(WMO 1954; Hansman 1989; Schultz and Politovich 1992).

Are super-cooled drops present? 248 K < T11 < 273 K

Is water phase present?

• night T3.7 - T11 < - 2 K

• day T3.7 - T11 > 0 K ---- dependant on thickness of clouds with

use of visible data

Detecting Regions of Aircraft Icing

Icing likely in blue regions

Strengths:• POD: 55-70%

• FAR: 25%

• 4 km (Imager) product

Limitations:• detection obscured by high

clouds

• only a threshold -- no estimate of amount of icing

Icing Cloud-top Height

> 18,000 ft BLUE> 12,000 ft CYAN> 6,000 ft YELLOW< 6,000 ft ORANGE

If icing is possible, assign a height to the tops of the super-cooled clouds.

Use cloud-top pressure/height from corresponding GOES Sounder data

• mixture of CO2 slicing and IR assignment techniques

• icing height given in units of thousands of feet

Icing Enhanced Cloud-top Altitude Product (ICECAP)

Fog Detection and Vertical Thickness (depth)

Fog Detection:Variations in Channel Emission

This technique can be used not only on GOES satellite imagers, but also MODIS (Terra and Aqua) and VIIRS (on NPOESS).

Night-time differences:

• T11 – T3.9 > 0 K fog

An example which validates the fog depth product against observations is shown at the right.

Figures courtesy of Gary Ellrod

Emissivity differences between the 11 and 3.9 μm bands are used to determine the fog depth.

GOES Fog Depth Product in AWIPS

Colors indicate depth of fog, and non-fog or middle/high cloud regions are denoted in shades of cyan.

Limitations:• sub-pixel clouds add to the

uncertainty of the fog depth

• not applicable in multi-layer cloud regions

• product uncertainty over non-vegetated (low emissivity) surfaces

• only valid at night

Fog Depth

Fog Depth< 200 m GREEN200-300 m BLUE300-400 m RED400-500 m YELLOWNon-Fog CYAN

Low Cloud Base Estimation

Low Cloud Base

The POD and FAR statistics are based on more than 1500 cases (Ellrod 1996).

Ceiling Height< 1,000 ft RED> 1,000 ft GREENCirrus CYAN

Low Cloud BaseStrengths:• POD: 70%

• FAR: 10%

Limitations:• sub-pixel clouds add to the

uncertainty of the cloud base estimates

• not applicable in multi-layer cloud regions

Instrument Flight Rule (IFR) ceilings (< 1000 ft) are likely to occur when:

T11 – Tsfc < 4 K

Red regions indicate the likelihood of ceilings < 1000 ft; green for ceilings above 1000 ft. Cyan shades highlight regions of high clouds.

Summary of GOES Aviation Products

Icing Mask Icing Height Fog Depth Low Cloud Base

Hourly Hourly 15 min. Hourly

Night-time Night-time

*all products are available at 4 km resolution

SPoRT Program

http://weather.msfc.nasa.gov/sport - main SPoRT web page

SPoRT Satellite Observations

http://weather.msfc.nasa.gov/sport/sport_observations.html - real-time data from MODIS and AMSR-E

GOES Products for SPoRT

http://weather.msfc.nasa.gov/goesprod/ - GOES products produced for SPoRT including NESDIS aviation products

Additional Information -- SPoRT

Additional Information -- Aviation Products

COMET Aviation Training Resources MetEd Module: http://meted.ucar.edu/topics_aviation.php Fog and Low Cloud: http://meted.ucar.edu/dlac/website/expsat.htm

Web-based ProductsNESDIS - Operational Products Development Branch Aviation Products:

http://www.orbit.nesdis.noaa.gov/smcd/opdb/aviation/icg.html Cloud and Fog Products:

http://www.orbit.nesdis.noaa.gov/smcd/opdb/aviation/fog.html

NWS - Aviation Weather Center (AWC) Forecast Icing Potential (FIP): http://aviationweather.gov/exp/fip/ Current Icing Potential (CIP): http://aviationweather.gov/exp/cip/

Additional Information -- References

• Brown, B., 1996: Verification of in-flight icing forecasts: Methods and issues. FAA Intl. Conf. on Aircraft Icing, Springfield, VA, May 6-8, 1996.

• Ellrod, G. P., 1995: Advances in the detection and analysis of fog at night using GOES multispectral infrared imagery. Wea. Forecasting, 10, 606-619.

• Ellrod, G. P., 1996: The use of GOES-8 multispectral imagery for the detection of aircraft icing regions. Preprint Volume, 8th Conf. on Satellite Meteorology and Oceanography, January 28-February 2, 1996, Atlanta, AMS, 168-171.

• Ellrod, G. P., 2000: Proposed improvements to the nighttime GOES fog product to improve ceiling and visibility information. Preprint Volume, 10th Conf. on Satellite Meteorology and Oceanography, 9-14 January, 2000, Long Beach, AMS, 454-456.

• Hansman, R. J., 1989: The influence of ice accretion physics on the forecasting of aircraft icing conditions. Preprint Volume, 3rd Intl. Conf. on the Aviation Weather System, January 30-February 3, 1989, Anaheim, AMS, 154-158.

• Schultz, P. and M. Politovich, 1992: Toward the improvement of aircraft-icing forecasts for the continental United States. Wea. Forecasting, 7, 491-500.

• Vivekanandan, J., G. Thompson, and T. F. Lee, 1996: Aircraft icing detection using satellite data and weather forecast model results. FAA Intl. Conf. on Aircraft Icing, Springfield, VA, May 6-8, 1996.

• WMO, 1954: Meteorological aspects of aircraft icing. WMO Tech. Note No. 3, WMO - No. 30. TP9, World Meteor. Org., Geneva, 18 pp.