Nowcasting Aircraft Icing Conditions Using GOES- Derived Cloud Products Cory A. Wolff Ben C. Bernstein Frank McDonough World Weather Research Program Symposium on Nowcasting and Very Short Range Forecasting Toulouse, France September 5-9, 2005

NASA Glenn Research Center Instrumented Twin Otter –FSSP, 2D Grey, King LWC, Nevzorov Fly into known icing conditions –Test aircraft response –Document conditions NCAR provides short term forecasts & nowcasts

Standard Tools NWP Model Geostationary Satellite (GOES) –CTT and albedo Radar Surface Observations –Precipitation type –Cloud base and coverage Pilot Reports

Effective Radius –Estimate of drop size –Usually “large” or “small” New Tools Developed at NASA Langley Research Center GOES Derived Cloud Products (GDCP) Phase –Clear –Ice –Liquid (T < 0°C) –Liquid (T > 0°C) Liquid Water Path (LWP) –Estimate liquid water content (LWC) at cloud top –Trends in LWC often follow LWP

16 February 2005 Icing encounter near Cleveland, OH GDCP useful in nowcasting

1200 UTC Briefing Snow in region Upper layer pulling away at DTX Left with warm topped SLW cloud –PIREPs around DTX Flight postponed No GDCP yet Mid-level Drying CTT: -8 °C 1315 UTC

1415 UTC 1445 UTC 1515 UTC CLE

First Encounter Decision to fly made at 1400 UTC –First daytime GDCP at 1415 UTC –Not available until ~1445 UTC Between CLE and SKY (1509 – 1542 UTC)

1515 UTC 1545 UTC 1615 UTC CLE

Second Encounter LWP maximum and brighter clouds had moved east during performance tests Between CLE and CAK (1553 – 1629 UTC)

Summary Standard encounters –Cloud top had highest LWC GDCP were helpful –Extra confidence –Higher LWC found near LWP max Effective Radius –GDCP suggested small drops –Aircraft measured MVD: 10 – 18 µm