Aviation and Marine Applications

1. Aviation and Marine Applications COMET Satellite Meteorology Gary Ellrod (NOAA/NESDIS) Camp Springs, Maryland SatMet 99-2 Thursday, 29 April 1999

2. Aviation/Marine Outline • Aviation • Stratus and fog • Aircraft icing • Jet streams / Clear Air Turbulence (CAT) • Mountain waves • Microbursts / gust fronts • Marine • Sea fog • Oceanic convection • Surface winds / cyclones

6. Is it fog or Sc/Ac? • Fog looks smoother • Sc/Ac is “mottled” • Fog is brighter (if depth equal) • Fog has distinct edges • Higher clouds may have “shadows” • Fog is warmer in CH4 IR (10.7 mm) • Fog moves/develops more slowly

8. Resolution vs Fog Detection

11. Meteorological Factors Conducive to Icing • Temperature (0 to -20C) • Liquid Phase (supercooled droplets) • Large drop sizes (>50 mm) • High Liquid Water Content (>0.25 gm-3) • Weak vertical motion (~1 mbar s-1) • Embedded convection • Large areal extent

13. GOES Channels Useful in Icing Detection • Visible (0.6 mm) • Thickness, coverage, phase, convection • IR2 (3.9 mm) • Cloud phase, drop size • IR4 (10.7 mm) • Cloud top temperatures, thickness, coverage • IR5 (12.0 mm) • Thin cirrus detection

14. GOES Icing Risk Product • Multiple channel screening technique • Product available hourly day and night • Strengths • High POD (~70%), low FAR • Good spatial, temporal coverage • Weaknesses • Obscuration by high clouds • No data 2 hr after sunrise / before sunset

16. Turbulence-Generating Mechanisms • Shear instability along jet and upper fronts • Flow over obstacles • Mountains • Thunderstorms • Convection (thunderstorms, dry thermals) • Low level “mechanical” (strong winds over rough terrain) • Wake turbulence from other aircraft

17. Detection of Turbulence Using Satellite Imagery • Clear Air Turbulence (CAT) • Water vapor imagery (8 km) • Subsidence warming with time along fronts • Infrared (4 km) • Transverse cirrus cloud bands • Deformation zone cloud boundaries • Visible (1 km) • Billow wave clouds (K-H instability) • Mountain waves • Transverse cloud bands (IR/Vis) • Lee-of-mountain cirrus with lee gap (IR/WV)

23. Extreme Turbulence Scenario • Environmental conditions: • Strong jet intersects: • Cold front with: • Low top convection • Extreme turbulence possible downwind from convection

28. Pilot Reports - 4 Feb 99/15-18Z

31. Microburst/Downburst Detection with GOES • Leading Edge (IR) Gradients (LEG) - mirrors WSR-88D reflectivity gradients • Anvil warming to rear of storm (IR) - evidence of rear inflow jet • Extensive clouds to rear of gust fronts • Rapid storm motion • GOES Sounder products • WIND Index (WINDEX) • Dry Microburst Potential (DMPI) • Max. Theta-e Difference (Sfc-300mb)

39. Hazards of Volcanic Ash • Reduced engine performance, possible stalls • Abrasion, pitting of leading edges • Electrical discharges (St. Elmo’s fire) • Ash difficult for pilots to see at night • Volcanoes in remote areas (North Pacific) where few alternate airfields available • Height/depth of ash difficult to determine

42. Smoke as an Aviation Hazard

43. Marine Applications • Sea fog • Oceanic convection • Cyclones • Strong wind zones • Quantitative surface wind data

46. Cloud Streets/ Open Cell Convection

47. Gulf Stream Convection

48. Strong Wind Zones in Oceanic Cyclones • Indicators of Rapid Cyclogenesis • Cloud pattern evolution (leaf to 360o comma in < 18 hours) • Strong dry slot subsidence (warming in WV) • Mesoscale Cloud Features • Closely spaced cloud streets • “Open cell” convection / arc lines • “Ring Cloud” feature at storm center • Hooking or sharply-tapered comma head