The advective Brewer–Dobson circulation in the ERA5 reanalysis: climatology, variability, and trends

Abstract. The stratospheric Brewer–Dobson circulation (BDC) is an important element of climate as it determines the transport and distributions key radiatively active atmospheric trace gases, which affect Earth's radiation budget surface climate. Here, we evaluate interannual variability, climatology, trends BDC in ERA5 reanalysis intercompare them with its predecessor, ERA-Interim reanalysis, for 1979–2018 period. We also assess modulation by Quasi-Biennial Oscillation (QBO) El Niño–Southern (ENSO), well forcings planetary gravity wave drag. comparison reanalyses shows a very good agreement morphology structural modulations natural variability related to QBO ENSO. Despite spatial structure, there are substantial significant differences strength impacts on between two reanalyses, particularly upper troposphere lower stratosphere (UTLS) stratosphere. Throughout most regions stratosphere, advective stronger due forcings, except UTLS below 20 km where tropical upwelling up 40 % weaker mainly significantly forcing at equatorial-ward flank subtropical jet. In extratropics, large-scale downwelling than that linked Analysis trend global insignificant acceleration annual mean residual rate about 1.5 decade−1 70 hPa long-term intensification breaking, consistent observed modelled changes. Our findings suggest from kinematic suited model validation mid-stratosphere when using standard formula zonally averaged zonal momentum equation. reported may nudged simulations. Therefore, additional studies needed investigate whether or not nudging models toward will reproduce free-running simulations ERA5. Finally, further better understand impact new non-orographic parameterization scheme, higher top, representation sponge layer polar regions.