Altimetric wavenumber spectra: noise floors and resolution capability
Event: 2017 Ocean Surface Topography Science Team Meeting
Session: Quantifying Errors and Uncertainties in Altimetry data
Presentation type: Type Oral
Contribution: PDF file
Recent progress in satellite altimetry has greatly improved the observability of mesoscale structures in the ocean. Here we analyze the noise levels and observable spatial scales for the global ocean using the wavenumber spectra of the three-year SARAL/Altika 1Hz Sea Surface Height (SSH) along-track measurements. We observe that noise estimations (for the wavelength range 15-30 km) tend to deviate from a purely white noise spectrum in regions of low eddy energy, and in particular inside the tropical band (15°S-15°N). Noise levels also vary seasonally, with an overall higher noise level during winter months in comparison to summer. The capability for resolving fine spatial scales also varies as a consequence of the noise level seasonality. During winter months, the observable wavelength reduces by about 5 to 20 km with respect to summer season. In general, these variations are less important in western boundary current systems in comparison to less energetic current systems, given the relatively favorable signal to noise ratio that is found in western boundary current systems.