Motion-correlated flow distortion and wave-induced biases in air–sea flux measurements from ships
Direct measurements of the turbulent air–sea fluxes of momentum, heat, moisture and gases are often made using sensors mounted on ships. Ship-based turbulent wind measurements are corrected for platform motion using well established techniques, but biases at scales associated with wave and platform...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/10619/2015/acp-15-10619-2015.pdf |
| Summary: | Direct measurements of the turbulent air–sea fluxes of momentum, heat,
moisture and gases are often made using sensors mounted on ships. Ship-based
turbulent wind measurements are corrected for platform motion using well
established techniques, but biases at scales associated with wave and
platform motion are often still apparent in the flux measurements. It has
been uncertain whether this signal is due to time-varying distortion of the
air flow over the platform or to wind–wave interactions impacting the
turbulence. Methods for removing such motion-scale biases from scalar
measurements have previously been published but their application to
momentum flux measurements remains controversial. Here we show that the
measured motion-scale bias has a dependence on the horizontal ship velocity
and that a correction for it reduces the dependence of the measured momentum
flux on the orientation of the ship to the wind. We conclude that the bias
is due to experimental error and that time-varying motion-dependent flow
distortion is the likely source. |
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| ISSN: | 1680-7316 1680-7324 |