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- Title
Characterizing Buoy Wind Speed Error in High Winds and Varying Sea State with ASCAT and ERA5.
- Authors
Wright, Ethan E.; Bourassa, Mark A.; Stoffelen, Ad; Bidlot, Jean-Raymond
- Abstract
Buoys provide key observations of wind speed over the ocean and are routinely used as a source of validation data for satellite wind products. However, the movement of buoys in high seas and the airflow over waves might cause inaccurate readings, raising concern when buoys are used as a source of wind speed comparison data. The relative accuracy of buoy winds is quantified through a triple collocation (TC) exercise comparing buoy winds to winds from ASCAT and ERA5. Differences between calibrated buoy winds and ASCAT are analyzed through separating the residuals by anemometer height and testing under high wind-wave and swell conditions. First, we converted buoy winds measured near 3, 4, and 5 m to stress-equivalent winds at 10 m ( U 10 S ). Buoy U 10 S from anemometers near 3 m compared notably lower than buoy U 10 S from anemometers near 4 and 5 m, illustrating the importance of buoy choice in comparisons with remote sensing data. Using TC calibration of buoy U 10 S to ASCAT in pure wind-wave conditions, we found that there was a small, but statistically significant difference between height adjusted buoy winds from buoys with 4 and 5 m anemometers compared to the same ASCAT wind speed ranges in high seas. However, this result does not follow conventional arguments for wave sheltering of buoy winds, whereby the lower anemometer height winds are distorted more than the higher anemometer height winds in high winds and high seas. We concluded that wave sheltering is not significantly affecting the winds from buoys between 4 and 5 m with high confidence for winds under 18 ms−1. Further differences between buoy U 10 S and ASCAT winds are observed in high swell conditions, motivating the need to consider the possible effects of sea state on ASCAT winds.
- Subjects
OCEAN waves; WIND speed; BUOYS; REMOTE sensing
- Publication
Remote Sensing, 2021, Vol 13, Issue 22, p4558
- ISSN
2072-4292
- Publication type
Article
- DOI
10.3390/rs13224558