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number = {2},  pages = {913--937},  volume = {14},  abstract = {Abstract. {{Abstract.  In this study we use the ERA-Interim reanalysis data set from the European Centre for Medium-Range Weather Forecasts (ECMWF) and a refined version of a previously developed Lagrangian methodology to compile a global 33 yr climatology of stratosphere–troposphere exchange (STE) from 1979 to 2011. Fluxes of mass and ozone are calculated across the tropopause, pressure surfaces in the troposphere, and the top of the planetary boundary layer (PBL). This climatology provides a state-of-the-art quantification of the geographical distribution of STE and the preferred transport pathways, as well as insight into the temporal evolution of STE during the last 33 yr. We confirm the distinct zonal and seasonal asymmetry found in previous studies using comparable methods. The subset of deep STE, where stratospheric air reaches the PBL within 4 days or vice versa, shows especially strong geographical and seasonal variations. The global hotspots for deep STE are found along the west coast of North America and over the Tibetan Plateau, especially in boreal winter and spring. An analysis of the time series reveals significant positive trends of the net downward mass flux and of deep STE in both directions, which are particularly large over North America. The downward ozone flux across the tropopause is dominated by the seasonal cycle of ozone concentrations at the tropopause and peaks in summer, when the mass flux is nearly at its minimum. For the subset of deep STE events, the situation is reversed and the downward ozone flux into the PBL is dominated by the mass flux and peaks in early spring. Thus surface ozone concentration along the west coast of North America and around the Tibetan Plateau are likely to be influenced by deep stratospheric intrusions. We discuss the sensitivity of our results on the choice of the control surface representing the tropopause, the horizontal and vertical resolution of the trajectory starting grid, and the minimum residence time τ used to filter out transient STE trajectories.}, trajectories.}  Latitude based analogy of where STTs and deep STTs occur occur},  doi = {10.5194/acp-14-913-2014},  url = {http://www.atmos-chem-phys.net/14/913/2014/},  } 
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number = {6},  pages = {3121--3132},  volume = {13},  abstract = {Abstract. {{Abstract.  Two years of Very High Frequency (VHF) radar echo power observations are used to examine the structure and variability of the tropopause at Davis, Antarctica. Co-located radiosonde and ozonesonde launches provide data with which to calculate the lapse-rate and chemical tropopauses. The radar tropopause, defined as the maximum vertical gradient of echo return power, can be used as a definition of the Antarctic tropopause throughout the year under all meteorological conditions. During the extended summer period of December–April (DJFMA) inclusive, radar tropopauses are (0.2 ± 0.4) km lower than radiosonde lapse-rate (i.e. the World Meteorological Organisation – WMO) tropopauses and during the extended winter period of June–October (JJASO) inclusive, the radar tropopauses are (0.8 ± 1.0) km lower. A potential vorticity tropopause is defined as the altitude of the −2 PVU surface (where 1 PVU = 106 m2 s−1 K kg−1). This is (0.3 ± 0.5) km lower than the radar tropopause during DJFMA and (0.5 ± 1.0) km lower during JJASO. The radar, potential vorticity and ozone tropopauses decrease in altitude during increasingly strong cyclonic conditions, in contrast to the radiosonde WMO tropopause which remains nearly constant. During strong JJASO cyclonic conditions, there are large (several km) differences between WMO tropopause altitudes and radar tropopause altitudes. A seasonal cycle in tropopause fold occurrence is observed, with approximately a three-fold increase during JJASO.}, JJASO.}  Tropopause Definition taken from here here},  doi = {10.5194/acp-13-3121-2013},  url = {http://www.atmos-chem-phys.net/13/3121/2013/},  } 
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number = {532},  pages = {929--944},  volume = {122},  abstract = {A {{A  comparison has been conducted of the height and sharpness of the tropopause as revealed by temperature and ozone profiles. In the study, 628 ECC-type ozonesonde profiles from four stations in northern Europe were used. Two tropopauses were defined for each profile: a thermal tropopause and an ozone tropopause defined in terms of both mixing ratio and vertical gradient of mixing ratio. On average, the ozone tropopause lay 800 m below the thermal. Large differences in tropopause height were associated with indefinite thermal tropopauses which were, in turn, often associated with cyclonic conditions (some corresponding to profiles taken within the stratospheric polar vortex). On almost all profiles the thermal tropopause was the higher of the two, and of the 15 profiles that did not fit this pattern, two-thirds were associated with anticyclonic flow in the upper troposphere. It is also shown that the tropopause definition impacts greatly on the evaluation of the ozone content of the troposphere. Where the thermal tropopause is indefinite in character, on average 27% of the ozone found below the thermal tropopause lies above the ozone tropopause.}, tropopause.}  Ozone vs thermal tropopause definitions definitions},  doi = {10.1002/qj.49712253207},  issn = {1477-870X},  keywords = {Ozone profiles, Temperature profiles, Tropopause definition}, 
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title = {{Sources contributing to background surface ozone in the {US} Intermountain West}},  journal = {Atmos. Chem. Phys.},  }  @article{Terao_2008,  doi = {10.1029/2008jd009854},  url = {http://dx.doi.org/10.1029/2008jd009854},  year = {2008},  publisher = {Wiley-Blackwell},  volume = {113},  number = {D18},  author = {Yukio Terao and Jennifer A. Logan and Anne R. Douglass and Richard S. Stolarski},  title = {{Contribution of stratospheric ozone to the interannual variability of tropospheric ozone in the northern extratropics}},  journal = {J. Geophys. Res.},  }