Observational study of the marine atmospheric boundary layer characteristics during swell

• By combining simultaneous data from an instrumented Air-Sea Interaction   Spar (ASIS) buoy and a 30-m tower, profiles of wind and turbulence   characteristics have been obtained at several heights from about 1 to   30 m above the water surface during swell conditions. Five cases formed   as averages over time periods ranging from 2.5 to 9.5 h, representing   quasi-steady conditions, have been selected. They represent a range of   typical wave age and include wind-following swell cases and cross-swell   cases. For relatively large wave age, the wind profile exhibits a   well-defined maximum in the height range 5-10 m; for more modest wave   age, this maximum turns into a sharp "knee'' in the wind profile. Below   the maximum ( or knee), the wind increases rapidly with height; above   that point the wind is very nearly constant up to the highest measuring   level on the tower, 30 m. Analysis of balloon data from one day with   swell indicates that the layer with constant wind in fact extends to   the top of the boundary layer, in this case similar to 200 m. Analysis   of the complete swell dataset from the 45 days of the 2003 Baltic Swell   experiment shows that the results concerning wind profile shape   obtained from the selected cases are generally valid in this   experiment. Analysis of the nondimensional wind profile phi(m) shows   that Monin-Obukhov scaling is not valid during swell. Wind and   turbulence characteristics are found not to vary to a significant   degree with the wind/swell angle within the range of angles   encountered, +/- 90 degrees.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Earth sciences

Geovetenskap

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