Figure 3: Synthetic mean
velocities in the Mid Atlantic Bight region off New Jersey and Delaware,
estimated (a) from drifting buoy (at 1/8°) and (b) from HF radar data.
Black lines represent 100m and 2000m isobaths.
2.4 Multivariate objective analysis
The third step of this method is multivariate objective analysis as in
Rio and Hernandez (2004), Rio et al. (2007, 2011 and 2014a) and in Mulet
et al. (2021), which uses the synthetic mean geostrophic velocities and
synthetic mean heights to improve the first guess, in particular to
improve the fine scales, to obtain the CNES-CLS22 MDT. This optimal
analysis requires the a priori MDT variance and the a priori zonal and
meridional spatial correlation scales of the estimated field. The same
statistical a priori as for Rio et al. (2014a) and Mulet et al. (2021)
are used here. In the equatorial band, as the geostrophic approximation
is no longer valid, only mean synthetic height observations are used for
MDT estimation, and for current estimation, only mean synthetic
velocities observations are used for inversion.