An Assessment of the Meteorological Conditions Leading to the NOAA WP-3D Engine Compressor Stalls of February 9, 2007, Due to Sea Salt Aerosol Particle Fouling

• Main Authors: Reid, Jeffrey S, Eleuterio, Daniel P, Cook, B J, Walker, Annette L, Richardson, Kim A, Westphal, Douglas L, Zhang, Jianglong, Damiano, A B, McNamara, Richard J, Mayeaux, Martin
• Format: Report
• Language: English
• Subjects: ADVECTION; AEROSOLS; AIRCRAFT ENGINES; ATMOSPHERIC INSTABILITY; BOUNDARY LAYER; COMPRESSOR STALLS; CONCENTRATION(COMPOSITION); CYCLOGENESIS; DRY POLAR AIR; FOULING; FRONTS(METEOROLOGY); GULF STREAM; HIGH SEAS; HIGH WINDS; HURRICANES; IN SITU ANALYSIS; MARINE ATMOSPHERES; MARINE BOUNDARY LAYER; MARINE METEOROLOGY; METEOROLOGICAL DATA; Meteorology; Military Aircraft Operations; NAVAL RESEARCH; NORTH ATLANTIC OCEAN; PARTICLES; Physical and Dynamic Oceanography; POLAR REGIONS; RESEARCH AIRCRAFT; Research and Experimental Aircraft; SALTS; SATELLITE METEOROLOGY; SEA SALT FOULING; SEA WATER; SEVERE WEATHER; STALLING; TURBULENCE; WARM GULFSTREAM WATERS

This report presents the findings from a meteorological analysis of the NOAA WP-3D N42RF engine compressor stalls of February 9, 2007, which nearly led to the loss of the aircraft. Preliminary engineering and meteorological analysis performed by the NOAA pointed to sea salt fouling when the aircraft encountered super concentrations of sea salt aerosol particles in the atmosphere at an altitude above 1 km. To the authors' knowledge, this type of sea salt event is previously unrecorded in the peer-reviewed literature. Utilizing a combination of model, satellite, and in situ data, they tracked the flight environment for three research flights as part of the 2007 Ocean Winds Winter Experiment (OWWE) out of St. John's, Newfoundland, where the aircraft experienced hurricane force winds. Among the questions addressed were what conditions can lead to super concentrations of sea salt in the marine atmosphere and why was there a failure on the Feb 9 flight and not on others? In this particular case, the aircraft track took it into the dry slot behind the bent-back warm-type occluded front of a North Atlantic explosive cyclogenesis event. In this environment, dry polar air is advected at high wind speeds over the relatively warm waters of the Gulf Stream. This led to an environment of high winds, high seas, and massive atmospheric instability and turbulence along a 400 km fetch without precipitation. This allowed giant-sized sea salt particles to be well mixed in the marine boundary layer. By the authors' estimations, marine boundary layer heights for this flight were 1200 to 1500 m, well above the flight level of the aircraft. In comparison, other OWWE flights may have experienced high winds, but not the other causal factors determined for Feb 9. Lastly, since the WP-3D was intersecting warm, moist, and sea salt-laden updrafts in between longer periods of drier environments, it is possible that increased sea salt accretion developed through the oscillating wet-dry cycle. Prepared in cooperation with the National Oceanographic and Atmospheric Administration, Aircraft Operations Center, Tampa, FL. The original document contains color images.