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Title: On the predominance of unstable atmospheric conditions in the marine boundary layer offshore of the U.S. northeastern coast

The marine boundary layer of the northeastern U.S. is studied with focus on wind speed, atmospheric stability, and turbulent kinetic energy (TKE), the three most relevant properties in the context of offshore wind power development. Two long-term observational data sets are analyzed. The first one consists of multilevel meteorological variables measured up to 60 m during 2003–2011 at the offshore Cape Wind tower, located near the center of the Nantucket Sound. The second data set comes from the 2013–2014 IMPOWR campaign (Improving the Modeling and Prediction of Offshore Wind Resources), in which wind and wave data were collected with new instruments on the Cape Wind platform, in addition to meteorological data measured during 19 flight missions offshore of New York, Connecticut, Rhode Island, and Massachusetts. It is found that, in this region: (1) the offshore wind resource is remarkable, with monthly average wind speeds at 60 m exceeding 7 m s -1 all year round, highest winds in winter (10.1 m s -1) and lowest in summer (7.1 m s -1), and a distinct diurnal modulation, especially in summer; (2) the marine boundary layer is predominantly unstable (61% unstable vs. 21% neutral vs. 18% stable), meaning that mixing is strong,more » heat fluxes are positive, and the wind speed profile is often nonlogarithmic (~40% of the time); and (3) the shape of the wind speed profile (log versus nonlog) is an effective qualitative proxy for atmospheric stability, whereas TKE alone is not.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [2]
  1. Univ. of Delaware, Newark, DE (United States). College of Earth, Ocean, and Environment
  2. Stony Brook Univ., NY (United States). School of Marine and Atmospheric Sciences
Publication Date:
Grant/Contract Number:
EE0005377
Type:
Published Article
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 121; Journal Issue: 15; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Research Org:
Stony Brook Univ., Stony Brook, NY (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind Energy Technologies Office (EE-4WE)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; marine boundary layer; offshore wind; atmospheric stability; Obukhov length
OSTI Identifier:
1287748
Alternate Identifier(s):
OSTI ID: 1288989; OSTI ID: 1437641