Reanalysis intercomparison of potential vorticity and potential-vorticity-based diagnostics

Abstract. Global reanalyses from data assimilation systems are among the most widely used datasets in weather and climate studies, potential vorticity (PV) is invaluable for many studies of dynamical transport processes. We assess how consistently modern represent each other, focusing not only on PV but also process-oriented diagnostics including equivalent latitude calculated PV-based tropopause stratospheric polar vortex characterization. In particular we National Centers Environmental Prediction Climate Forecast System Reanalysis/Climate System, version 2 (CFSR/CFSv2) reanalysis, European Centre Medium-Range Weather Forecasts Interim (ERA-Interim) Japanese Meteorological Agency's 55-year (JRA-55) NASA Modern-Era Retrospective analysis Research Applications, (MERRA-2). Overall, all agrees well with reanalysis ensemble mean, providing some confidence that these recent suitable using diagnostics. Specific where larger differences seen include locations regions have strong gradients (such as around subtropical jets) or sparse high-resolution over Antarctica), vortices during fall formation (especially) spring breakup; sensitive situations such should examine multiple reanalyses.