Error in Measurements of Incoming Shortwave Radiation Made from Ships and Buoys

Abstract

Errors in shortwave solar radiation measurements resulting from mean tils and rocking motions, as well as from the response time of the sensors, are determined experimentally. The magnitude of the mean tilt error can be large and lead to errors in daily-averaged incoming shortwave radiation in excess of 10 W m?2. Mean errors due to rocking motions and time response errors are less severe. The spatial distribution of the diffuse component of the radiation and the motion of the platform must both be known to attempt to correct for this error. An algorithm to perform this correction was derived, yet is only sufficiently accurate when the time response of the pyranometer is significantly smaller than the period of the rocking motion. Gimballing the sensors may be a more practical method of error reduction.