A Case Study of Laser Wind Sensor Performance Validation by Comparison to an Existing Gage

Abstract

A case study concerning validation of wind speed measurements made by a laser wind sensor mounted on a 190 square foot floating platform in Muskegon Lake through comparison with measurements made by pre-existing cup anemometers mounted on a met tower on the shore line is presented.  The comparison strategy is to examine the difference in measurements over time using the paired-t statistical method to identify intervals when the measurements were equivalent and to provide explanatory information for the intervals when the measurements were not equivalent.  The data was partitioned into three sets: not windy (average wind speed measured by the cup anemometers ≤ 6.7m/s) windy but no enhanced turbulence (average wind speed measured by the cup anemometers > 6.7m/s), and windy with enhanced turbulence associated with storm periods.  For the not windy data set, the difference in the average wind speeds was equal in absolute value to the precision of the gages and not statistically significant.  Similar results were obtained for the windy with no enhanced turbulence data set and the average difference was not statistically significant (a=0.01). The windy with enhanced turbulence data set showed significant differences between the buoy mounted laser wind sensor and the on-shore mast mounted cup anemometers.  The sign of the average difference depended on the direction of the winds.  Overall, validation evidence is obtained in the absence of enhanced turbulence.  In addition, differences in wind speed during enhanced turbulence were isolated in time, studied and explained.

Keywords

• Laser wind sensor; validation; offshore wind energy; paired-t statistical method