Global and regional ocean and sea ice reanalysis products (ORAs) are increasingly used in polar research, but their quality remains to be systematically assessed. To address this, the Polar ORA Intercomparison Project (Polar ORA-IP) has been established following on from the ORA-IP project. Several aspects of ten selected ORAs in the Arctic and Antarctic were addressed by concentrating on comparing their mean states in terms of snow, sea ice, ocean transports and hydrography. Most polar diagnostics were carried out for the first time in such an extensive set of ORAs. For the multi-ORA mean state, we found that deviations from observations were typically smaller than individual ORA anomalies, often attributed to offsetting biases of individual ORAs. The ORA ensemble mean therefore appears to be a useful product and while knowing its main deficiencies and recognising its restrictions, it can be used to gain useful information on the physical state of the polar marine environment.

The discovery of the Higgs boson with its mass around 125 GeV by the ATLAS and CMS Collaborations marked the beginning of a new era in high energy physics. The Higgs boson will be the subject of extensive studies of the ongoing LHC program. At the same time, lepton collider based Higgs factories have been proposed as a possible next step beyond the LHC, with its main goal to precisely measure the properties of the Higgs boson and probe potential new physics associated with the Higgs boson. The Circular Electron Positron Collider (CEPC) is one of such proposed Higgs factories. The CEPC is an e + e − circular collider proposed by and to be hosted in China. Located in a tunnel of approximately 100 km in circumference, it will operate at a center-of-mass energy of 240 GeV as the Higgs factory. In this paper, we present the first estimates on the precision of the Higgs boson property measurements achievable at the CEPC and discuss implications of these measurements.

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[1] Southern Ocean (SO) sea ice simulations are particularly sensitive to wind forcing. Two real-time wind data sets covering the same period are employed to force SO sea ice in a sea ice-ocean general circulation model. Both data sets are analysis products, featuring the same temporal resolution but differing in their horizontal resolution and their source. Even in simulations where the upper ocean temperature is constrained by satellite-derived sea ice concentration, the sea ice simulations and associated surface buoyancy fluxes reveal pronounced differences along the Antarctic coastline. While the discrepancies cannot unambiguously be related to the different resolution of the wind forcing, their concentration along the coastline is indicative of being related to the representation of orography, such as coastal steep slopes and mountain ranges, including their ruggedness. Along the coast of the Weddell Sea, the net ice production rate increases by about a factor of 3 with the higher-resolution winds. On the other hand, along east Antarctica, the lower-resolution winds result in higher ice production, due to a generally stronger (overestimated) offshore component, presumably related to the smoother orography extending seaward beyond the coastline. This regionally opposite behavior leads to a relatively weak difference in total dense water formation around Antarctica and thus global deep ocean properties and circulation. Overall, the results indicate that long-term climate model projections are likely to be highly sensitive to model resolution in the Antarctic coastal zone.