THE METEOROLOGICAL ENVIRONMENT SURROUNDING THE AIR FRANCE #447 DISASTER

摘要

Air France Flight #447 (AF447) descended into theNorth Atlantic Ocean early on 1 June 2009, killing all onboard. Contact with the Airbus A330 was lost when theflight was several hundred kilometers northeast of theSouth American coast at an altitude of ~12 km while theaircraft was in proximity to widespread deep convection,which was estimated via satellite to exceed 17 km.There has been much speculation but very little proofthat weather played an important role in the incident asa result of icing, lightning, turbulence or somecombination of these hazards. Based upon the finalACARS transmission as well as South Americanradiosonde, satellite, and GFS analysis/simulation datait is possible to reconstruct the horizontal and verticalatmospheric structure at the meso-/on scale in proximityto the incident. These data lend one to speculate that afavorable environment for aviation turbulence may haveexisted at this time surrounding the deep convection,and we will describe some of these features in thispreprint. Implicit in our analysis is related research byVollmer (2008) and Kaplan et al. (2005) that serves as atheoretical/synoptic framework for the analysespresented hereThe larger scale environment during the 0000 –0300 UTC 1 June 2009 period contained the followingkey synoptic features near the location of the incident(approximately 30oW, 4oN) as determined from the 0000UTC Fernando de Noronha, Brazil sounding, GFSsimulations, GFS analyses, and satellite-derived cloudtrack wind fields as well as infra-red and water vaporimagery: 1) an anticyclonically curved 100-150 mbsubtropical jet streak oriented northwest-southeast inwhich the left exit region was approaching the incidentlocation, 2) an anticyclonically-curved 70-100 mbtropical jet streak oriented southwest-northeast in whichthe left exit region was approaching the incidentlocation, 3) a well-defined region of velocityconvergence just to the northwest of the moistconvection, which was occurring in proximity to andunder velocity divergence over the convection andbracketing the incident location in the vertical, 4)substantial cross-jet frontogenesis due to 70 mb warming over and just downstream from the incidentlocation, 5) increasing vertical wind directional shear inthe layers including 150 – 100 mb and 100 – 70 mbprimarily from northwest to north to southwest and 6) adry adiabatic layer between 150 and 100 mbundercutting a strengthening inversion in time inbetween 100 and 70 mb. The inversion above 100 mbwas also in proximity to the top of the moist convectionwithin the anvil region.