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- Title
Wind-driven Current in the East Sea Observed from Mini-met Drifters.
- Authors
Dong-Kyu Lee
- Abstract
A wind-driven current in the East Sea from Lagrangian measurements of wind and current at 15 m using MiniMet drifters was analyzed. Spectral analysis of the current from 217 pieces of a 10 day- long time series shows the dominant energy at the inertial frequency for the current at 15 m. Wind has energy peaks at a 0.2-0.5 cycles per day (cpd) frequency band. The power spectrum of the clockwise rotating component is predominant for the current and was 1.5-2 times larger than the anticlockwise rotating component for wind. Co-spectra between the wind and current show two peak frequency bands at sub- inertial frequency and 0.5-0.3 cpd. Coherences between the wind and current at those peak frequencies are significant with 95% confidence and phase differences were 90-100°. From the phase differences, the e-folding depth is estimated as 17 m and this e-folding depth is smaller than the estimation by Chereskin's (1999) 25 m using a moored Acoustic Doppler Current Profiler and an anemometer installed at the surface buoy. The angle between the wind-driven current (or ageostrophic current) and wind from this study was also much larger than the global estimate by Rio and Hernandez (2003) using reanalysis wind and drifters. The possible explanation for the discrepancy comes from the fact that the current is driven by a wind of smaller length scale than 250 km but the satellite or the reanalysis products do not resolve winds of length scale smaller than 250 km. Large rms differences between Mini-Met and QuickSCAT wind on spatial lags smaller than 175 km substantiate this explanation.
- Subjects
JAPAN Sea Coast (Korea); WIND speed measurement; ELECTROMAGNETIC current density measurement; WIND pressure; INERTIAL navigation systems; LAGRANGIAN functions
- Publication
Ocean & Polar Research, 2014, Vol 36, Issue 2, p103
- ISSN
1598-141X
- Publication type
Article
- DOI
10.4217/OPR.2014.36.2.103