Interannual response of global ocean hindcasts to a satellite-based correction of precipitation fluxes.

We present a methodology to correct precipitation fluxes from the ECMWF atmospheric reanalysis (ERA-Interim) for oceanographic applications. The correction is performed by means of a spatially varying monthly climatological coefficient, computed within the period 1989-2008 by comparison between ERA-Interim and a satellite-based passive microwave precipitation product. ERA-Interim exhibits a systematic over-estimation of precipitation within the inter-tropical convergence zones (up to 3mmd-1) and underestimation at mid- and high- latitudes (up to -4mmd-1). The correction has been validated within eddy-permitting resolution global ocean hindcasts (1989-2009), demon strating the ability of our strategy in attenuating the 20-yr mean global EMP negative imbalance by 16 %, reducing the near-surface salinity fresh bias in the Tropics up to 1 psu and improving the representation of the sea level interannual variability, with an SSH error decrease of 8%. The ocean circulation is also proved to benefit from the correction, especially in correspondence of the Antarctic Circumpolar Current, where the error in the near-surface current speed decreases by a 9%. Finally, we show that the correction leads to volume and freshwater transports that better agree with independent estimates. [ABSTRACT FROM AUTHOR]