On the mesoscale monitoring capability of Argo floats in the Mediterranean Sea
Other literature type
(issn: 1812-0792, eissn: 1812-0792)
In this work an Observing System Simulation Experiment (OSSE) approach is used to investigate the Argo array spatial sampling necessary in the Mediterranean Sea to recover the mesoscale signal as seen by altimetry. The monitoring of the mesoscale features is not an initial objective of the Argo network. However, it is an interesting question in the perspective of future network extensions in order to improve the ocean state estimates. A quality assessment of the performances of the altimeter product is carried out to quantify the differences between Argo and altimetry needed to conduct the simulation experiments. The method used here to evaluate the altimeter data is based on the comparison of Sea Level Anomalies (SLA) from altimetry and Dynamic Height Anomalies (DHA) referred to both 400 and 900 dbar computed from the in-situ Argo network. A standard deviation of the differences between SLA and DHA of 4.92 cm is obtained when comparing altimetry and Argo data referred to 400 dbar. The simulation experiments show that a configuration similar to the current Argo array in the Mediterranean (with a spatial resolution of 2° × 2°) is only able to recover the large-scale signals of the basin. On the contrary, the SLA field reconstructed from a 0.75° x 0.75° Argo network can retrieve most of the mesoscale signal. Such an Argo array of around 450 floats in the Mediterranean Sea would be enough to recover the SLA field with an RMSE of 3 cm for spatial scales higher than 150 km, similar to those captured by the altimetry.