The Brewer–Dobson circulation inferred from ERA‐Interim

Seviour, William J. M.; Butchart, Neal; Hardiman, Steven C.

doi:10.1002/qj.966

Cited by 114 publications

(157 citation statements)

References 31 publications

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“…After 1995 the ERA-Interim data show a negative trend in the tropical upward mass flux (at 70/74 hPa), which is not captured by the model simulations. As shown by Seviour et al (2012), this negative trend contains large uncertainties, and does not occur in other reanalysis systems or when using different estimates of upwelling in ERA-Interim (Abalos et al, 2015). The nudged simulations, especially the simulations RC1SD-base-09/10 without global mean temperature nudging, are closer to ERA-Interim data than the RC1-simulations without nudging.…”

Section: Stratospheric Dynamicsmentioning

confidence: 73%

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

et al. 2016

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Abstract. Three types of reference simulations, as recommended by the Chemistry-Climate Model Initiative (CCMI), have been performed with version 2.51 of the European Centre for Medium-Range Weather Forecasts -Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model: hindcast simulations , hindcast simulations with specified dynamics , i.e. nudged towards ERA-Interim reanalysis data, and combined hindcast and projection simulations . The manuscript summarizes the updates of the model system and details the different model set-ups used, including the on-line calculated diagnostics. Simulations have been performed with two different nudging setups, with and without interactive tropospheric aerosol, and with and without a coupled ocean model. Two different vertical resolutions have been applied. The on-line calculated sources and sinks of reactive species are quantified and a first evaluation of the simulation results from a global perspective is provided as a quality check of the data. The focus is on the intercomparison of the different model set-ups. The simulation data will become publicly available via CCMI and the Climate and Environmental Retrieval and Archive (CERA) database of the German Climate Computing Centre (DKRZ). This manuscript is intended to serve as an extensive reference for further analyses of the Earth System Chemistry integrated Modelling (ESCiMo) simulations.

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Section: Stratospheric Dynamicsmentioning

confidence: 73%

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

et al. 2016

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“…The mean residual vertical velocity in the transformed Eulerian mean framework, calculated using the same method as Seviour et al (2012), and the dynamical heating used in Sect. 4 are both computed on the original grid from the ERA-Interim data and then smoothed by lin-early interpolating the monthly averages to daily values.…”

Section: Data and Radiative Methodsmentioning

confidence: 99%

The radiative role of ozone and water vapour in the annual temperature cycle in the tropical tropopause layer

Ming¹,

Maycock²,

Hitchcock³

et al. 2017

Atmos. Chem. Phys.

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Abstract. The structure and amplitude of the radiative contributions of the annual cycles in ozone and water vapour to the prominent annual cycle in temperatures in the tropical tropopause layer (TTL) are considered. This is done initially through a seasonally evolving fixed dynamical heating (SEFDH) calculation. The annual cycle in ozone is found to drive significant temperature changes predominantly locally (in the vertical) and roughly in phase with the observed TTL annual cycle. In contrast, temperature changes driven by the annual cycle in water vapour are out of phase with the latter. The effects are weaker than those of ozone but still quantitatively significant, particularly near the cold point (100 to 90 hPa) where there are substantial non-local effects from variations in water vapour in lower layers of the TTL. The combined radiative heating effect of the annual cycles in ozone and water vapour maximizes above the cold point and is one factor contributing to the vertical structure of the amplitude of the annual cycle in lower-stratospheric temperatures, which has a relatively localized maximum around 70 hPa. Other important factors are identified here: radiative damping timescales, which are shown to maximize over a deep layer centred on the cold point; the vertical structure of the dynamical heating; and non-radiative processes in the upper troposphere that are inferred to impose a strong constraint on tropical temperature perturbations below 130 hPa. The latitudinal structure of the radiative contributions to the annual cycle in temperatures is found to be substantially modified when the SEFDH assumption is relaxed and the dynamical response, as represented by a zonally symmetric calculation, is taken into account. The effect of the dynamical response is to reduce the strong latitudinal gradients and interhemispheric asymmetry seen in the purely radiative SEFDH temperature response, while leaving the 20 • N-20 • S average response relatively unchanged. The net contribution of the annual ozone and water vapour cycles to the peak-to-peak amplitude in the annual cycle of TTL temperatures is found to be around 35 % of the observed 8 K at 70 hPa, 40 % of 6 K at 90 hPa, and 45 % of 3 K at 100 hPa. The primary sensitivity of the calculated magnitude of the temperature response is identified as the assumed annual mean ozone mixing ratio in the TTL.

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“…We first consider the variations in the upwelling from below by the residual vertical velocity, w*. A large annual cycle in tropical w*, averaged over the tropics, has been reported [Rosenlof, 1995;Randel et al, 2007Randel et al, , 2008Yang et al, 2008;Seviour et al, 2012], but there has been less examination of the latitudinal variations within the tropics. These previous studies have also shown differences among w* obtained from different meteorological reanalysis products, so we examine w* from three reanalyses: ERA-40 [Uppala et al, 2005], ERA-Interim [Seviour et al, 2012], and Modern-Era Retrospective Analysis for Research and Applications (MERRA) [Rienecker et al, 2011].…”

Section: Seasonal Variations In Transportmentioning

confidence: 99%

Seasonal variation of ozone in the tropical lower stratosphere: Southern tropics are different from northern tropics

et al. 2014

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We examine the seasonal behavior of ozone by using measurements from various instruments including ozonesondes, Aura Microwave Limb Sounder, and Stratospheric Aerosol and Gas Experiment II. We find that the magnitude of the annual variation in ozone, as a percentage of the mean ozone, exhibits a maximum at or slightly above the tropical tropopause. The maximum is larger in the northern tropics than in the southern tropics, and the annual maximum of ozone in the southern tropics occurs 2 months later than that in the northern tropics, in contrast to usual assumption that the tropics can be treated as a horizontally homogeneous region. The seasonal cycles of ozone and other species in this part of the lower stratosphere result from a combination of the seasonal variation of the Brewer-Dobson circulation and the seasonal variation of tropical and midlatitude mixing. In the Northern Hemisphere, the impacts of upwelling and mixing between the tropics and midlatitudes on ozone are in phase and additive. In the Southern Hemisphere, they are not in phase. We apply a tropical leaky pipe model independently to each hemisphere to examine the relative roles of upwelling and mixing in the northern and southern tropical regions. Reasonable assumptions of the seasonal variation of upwelling and mixing yield a good description of the seasonal magnitude and phase in both the southern and northern tropics. The differences in the tracers and transport between the northern and southern tropical stratospheres suggest that the paradigm of well-mixed tropics needs to be revised to consider latitudinal variations within the tropics.

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The Brewer–Dobson circulation inferred from ERA‐Interim

Cited by 114 publications

References 31 publications

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

The radiative role of ozone and water vapour in the annual temperature cycle in the tropical tropopause layer

Seasonal variation of ozone in the tropical lower stratosphere: Southern tropics are different from northern tropics

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