AN ANALYSIS OF LOW-FREQUENCY MARITIME ATMOSPHERIC-TURBULENCE

New data are presented for the spectrum of turbulent wind energy under maritime conditions in the frequency region 1.0-0.03 mHz. The corresp onding measurements were made at five levels on a mast 46 m high on a small islet off the coast of central Norway. Twelve time series of len gth 10 h 40 min have been analyzed. The mean wind speeds of the series are in the range 11-19 m s(-1), and the wind directions are westerly, which have maritime conditions upwind. Four of the time series were c haracterized by unstable atmospheric conditions (mean lapse rate - par tial derivative T/partial derivative z in the range 12-20 K/km) and sh ow little or no indication of a spectral gap for heights above 40 m. F our other time series with stable to neutral conditions (mean lapse ra te 3-7 K/km) do show a gap in the wind speed spectra around 0.5 mHz, i n agreement with the Kansas (1972) and Minnesota (1978) experiments. T he remaining series, with lapse rates fluctuating around the neutral v alue of 9.8 K/km, show intermediate behavior. The temperature spectra at 45-m height do not show a gap even for stable to neutral conditions .