Progress of ERA5, and its use in studies of atmospheric trends and variability

Online seminar by Dr. Adrian Simmons from European Centre for Medium-Range Weather Forecasts

11 March 2022
KST 16:00 – 17:00

Join us online: Meeting ID: 831 0889 7960 Passcode: 961906

ERA5 is ECMWF’s latest comprehensive reanalysis of meteorological and related observations made over multiple decades. It has been released in final form covering 1979 onwards, with an improved (ERA5.1) version for 2000 to 2006. It is extended daily. A published provisional version for 1950-1978 will soon be superseded by a revision covering 1959-1978. Production of a final segment, covering 1940-1958, has started. In parallel, a two-year programme to prepare the successor reanalysis, ERA6, is under way.

Examples will be given of weather events and phenomena such as the QBO and stratospheric warmings for which reasonably reliable information can be given back to the 1950s. The exceptional severity of the rainfall near the border between Germany and Belgium in the first half of July 2021 will be illustrated. Some of the problems encountered in the earlier years of ERA5 will be mentioned.

The remainder of the talk will focus on temperature and wind changes over the better-observed period since 1979. Among the trends with high statistical significance are a little-discussed strengthening and latitudinal expansion of the tropical upper-tropospheric easterlies and the better-known strengthening of the lower-tropospheric easterlies over the tropical Pacific and westerlies around southern mid-latitudes. The Arctic amplification of warming has a more local effect on the general circulation than has been argued by some. Two of the areas where ICCP scientists have contributed relate to a strengthening of the upper-level westerlies in the Pacific cell of the tropical Walker Circulation and a general increase over time in kinetic energy. Links with ENSO variability are evident in many time series.