Comparison of Model Output of Wind and Wave Parameters with Spaceborne Altimeter Measurements

One of the major issues in the hindcasting and forecasting of winds and waves is the difficulty of validation and verification. While comparisons with point measurements from discrete and sparsely distributed wave buoys provide some measure of statistical confidence, the spatial distribution of the modeled wind and wave fields cannot be easily assessed. Remote sensing from space provides a synoptic view of the ocean wind and wave fields. For example, wind speed and significant wave height are standard output of spaceborne altimeters such as TOPEX/POSEIDON (hereafter referred to as TOPEX for brevity). Comparisons of the altimeter measured wind speed and wave height with surface buoy data have shown very positive agreement. With an along track resolution of 7 km, the spatial resolution of the spaceborne altimeter is comparable with that of the numerical models used for regional simulations. In the following, we present the results of a comparison study of WAM wave modeling of the Yellow and East China Seas (YES) with two of the TOPEX tracks in the region. In the next section the accuracy of TOPEX altimeter wind and wave measurements is summarized based on earlier studies of TOPEX and surface buoy comparisons. Section 3 describes the YES data sets and the background information about the numerical modeling and satellite tracks in the comparison region. Section 4 presents the results of the comparison in terms of statistics such as bias (B), rms difference (delta), regression coefficient (cand Cy, to be further discussed later) and correlation coefficient (R). Since altimeter remote sensing provides a spatial coverage of the wind and wave fields along transects, we will explore the use of such information for the validation of wave height distribution from a numerical wave model output. The conclusions and summary are presented in the last section of the paper.