Observations Of A Progressive Warm-Fresh Oceanic Front and A Cool-Moist Atmospheric Front At Duck, North Carolina

Abstract

This paper presents a unique set of observations of nearlycoincident and progressive oceanic and marine atmospheric boundary-layer (MABL) fronts in a coastal zone. The event was observed during the afternoon of 12 May 1996 at the United States Army Corps of Engineers, Coastal Engineering Research Center, Field Research Facility pier at Duck, North Carolina. The oceanic front was warm and fresh. Current variabilityaccompanied the oceanic front. A marked MABL front preceded the oceanic front by several minutes and had characteristics of a sea-breezefront. This MABL front separated warmer and dryer pre-frontal air from cooler and moister post-frontal air. Wind direction and wind speedvariability accompanied the MABL front. The sea-surface roughness signatures of both fronts were detected by an X-band pulsed Doppler radar. Supporting data are used to identify each front detected by the radar and to calculate each front's velocity. In an attempt to explain the sea-surface roughness variations associated with each front, the radar data are compared to corresponding variations in wind speed, wind direction, and air-sea temperature difference.