Interannual response of global ocean hindcasts to a satellite-based correction of precipitation fluxes
A. Storto1, I. Russo1, and S. Masina1,21Centro Euro-Mediterraneo per i Cambiamenti Climatici, viale A. Moro 44, 40127 Bologna, Italy 2Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy
Received: 27 Jan 2012 – Accepted for review: 02 Feb 2012 – Discussion started: 10 Feb 2012
Abstract. 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 3 mm d−1) and under-estimation at mid- and high- latitudes (up to −4 mm d−1). The correction has been validated within eddy-permitting resolution global ocean hindcasts (1989–2009), demonstrating 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.
Storto, A., Russo, I., and Masina, S.: Interannual response of global ocean hindcasts to a satellite-based correction of precipitation fluxes, Ocean Sci. Discuss., 9, 611-648, doi:10.5194/osd-9-611-2012, 2012.