Ocean reanalysis (ORA) combines observations either statistically or with a hydrodynamical model, to reconstruct historical changes in the ocean. Global and regional ORA products are increasingly used in the polar research, but their quality remains to be systematically assessed. To address this, the Polar ORA Intercomparison Project (PORA-IP) has been established following on from the ORA-IP project (Balmaseda et al. 2015 with other papers in a special issue of Climate Dynamics). The Polar ORA-IP is constituted under the COST EOS initiative with plans to review reanalyses products in both the Arctic and Antarctic, see example figures. Currently, the PORA-IP team consists of 20 researchers from 13 institutes and universities. The ORA-IP products with polar physics, such as sea ice, have been collected in a public database. In addition to model output, available observational polar climatologies are collected and used in the assessments. Due to the extensive variety of products, this database can be expected to become a valuable resource also outside the PORA-IP community.

Arctic Ocean heat content (1993-2010) 0-100m layer. The top left shows the Ensemble mean and Spread of 10 ORA-IP reanalysis products. Other fields show anomalies from the ORA-IP mean. The anomaly fields EN4, WOA13, PHC3 and HIROSHI represent different observation only climatologies.

PORA fig1

 Antarctic august (winter )mixed layer depths (1993-2010). ENS and STD are the ensemble mean and standard deviation of the 8 ORA-IP reanalysis products shown on the right hand side. OBS is the winter mixed layer depth observational climatology from Pellichero et al (2016, subm.)

PORA fig2

Year of Polar Prediction (YOPP) project endorsement can be downloaded from here.

More information can be obtained from the POLAR PREDICTION PROJECT website.

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