Intercomparison of the North Atlantic wave climatology from voluntary observing ships, satellite data and modelling

Abstract

Three different sources of the wave data - visual observations from the voluntary observing ships, wave hindcast from the WAM model driven by European Reanalysis Project winds, and the altimeter measurements from GEOSAT, TOPEX/POSEIDON and ERS-1 are used for the intercomparison of the North Atlantic wave fields for the period 1979–1993. Climatological spatial patterns of significant wave height seen in all three products are consistent, although the actual quantitative values indicate both positive and negative biases of about 0.1 to 0.8 m. Sea and swell heights are intercompared separately for the voluntary observing ship and WAM model data. Best agreement between the visually observed data, the model hindcast and the altimeter measurements is obtained in the North Atlantic mid latitudes. However, long-term wave height trends in the merchant ship and the WAM model data are quite different. The nature of the differences in these estimates is discussed.