Wave climate observed from altimeters: trends and extremes
Event: 2016 SAR Altimetry Workshop
Session: Applications, SAR for science
Presentation type: Type Poster
The wave climate has important implications to society and accurate knowledge is key for the mitigation of hazardous wave events in the coastal zone. Altimeters are the longest and most ample source of wave observations making them an attractive data source for study of the wave climate. Altimeters estimate the significant wave height estimated from the front slope of the emitted radar and wind speed from the backscatter coefficient. With the launch of GEOSAT in 1985 there is a near continuous coverage until present day. Here we continue the work of GlobWAVE to create a consistent wind and wave time series for climate studies. We then describe the wave climate from 1985-2016 using the merged altimeter dataset with interest in describing the trends and extreme sea states. Inter-annual variability plays an important role in the wave climate and we demonstrate the influence from the Arctic Oscillation, El Nino Southern Oscillation, and Antarctic Oscillation within the global ocean as well as in the Arctic Ocean, where decreasing sea ice is causing significant enhanced sea states. Lastly the altimeter sampling is assessed using a numerical wave hindcast. The under sampling of the extreme events affects the ability of the altimeters to statistically extrapolate extreme wave conditions. However, we can better understand the statistical distributions using numerical wave models that are properly calibrated with the altimeters for extreme wave events. This 31-year altimeter time series has many applications in wave climate extending previous efforts and demonstrating the importance of a consistent and continuous time series.