Determining Nonstationary Dynamic Events during an Air-Sea Interaction Field Campaign

Abstract:

Understanding the dynamics within the planetary boundary layer (PBL) over ocean surfaces is critical for offshore wind-energy assessment and prediction. Turbulence plays an important role in PBL dynamics. The turbulent motions vary with mechanical and buoyant forcing on scales larger than themselves, and the variation depends on the rate of change of large-scale forcing. The objective of this work is to determine the type and strength of nonstationary dynamic events in the marine PBL on scales larger than atmospheric turbulence. Data acquired during an air-sea interaction field campaign, the Ocean Horizontal Array Turbulence Study (OHATS), are analyzed using a recently developed multi-sensor stationarity analysis technique version 2 (MSATv2). Results show that the most nonstationary event determined by MSATv2 is an abrupt change in wind direction from along to against the local prevailing winds. The nonstationary dynamic events during the prevailing-wind episodes and the corresponding impacts on near-surface turbulence are of particular interest.