A Geodetic Approach to Mapping and Parametrization of Argo Temperature and Salinity Profiles

Abstract:

This study addresses mapping of Argo T/S profiles onto arbitrary positions using physically advanced statistical information from model fields, and their subsequent parametrization as function of depth. Argo suffers from spatio-temporal sampling problems, and some signals are not well captured e.g. in the deeper ocean below 2000m, around the boundary currents, in the Arctic or in the shelf/coastal regions which are not frequently visited by floats. Mapping of Argo data onto a predefined grid has become an established procedure in the scientific community, but is performed here by means of least squares collocation. The output of global ocean circulation models provide covariance information for least squares collocation and also complement the spatially undersampled Argo data in high latitudes and in deep ocean. The background model data receive a lower weight to discount them where sufficient Argo data exist but also to allow their use where Argo data are sparse. The parametrization of temperature an salinity profiles is performed with b-splines where the knot distance is based on T/S gradient. Furthermore, the parametrized profiles will pave the way for a fingerprint inversion framework, which is introduced here. This inverse problem schemewill jointly process radar altimetry, Argo and data from the Gravity Recovery and Climate Experiment (GRACE) yielding observation based estimates of consistent temperature, salinity and sea surface height changes.