ALBERT

Description: Land transport is an important emission source of nitrogen oxides, carbon monoxide, and volatile organic compounds. The emissions of nitrogen oxides affect air quality directly. Further, all of these emissions serve as a precursor for the formation of tropospheric ozone, thus leading to an indirect influence on air quality. In addition, ozone is radiatively active and its increase leads to a positive radiative forcing. Due to the strong non-linearity of the ozone chemistry, the contribution of emission sources to ozone cannot be calculated or measured directly. Instead, atmospheric chemistry models equipped with specific source attribution methods (e.g. tagging methods) are required. In this study we investigate the contribution of land transport emissions to ozone and ozone precursors using the MECO(n) model system (MESSy-fied ECHAM and COSMO models nested n times). This model system couples a global and a regional chemistry climate model and is equipped with a tagging diagnostic. We investigate the combined effect of long-range-transported ozone and ozone which is produced by European emissions by applying the tagging diagnostic simultaneously and consistently on the global and regional scale. We performed two simulations each covering 3 years with different anthropogenic emission inventories for Europe. We applied two regional refinements, i.e. one refinement covering Europe (50 km resolution) and one covering Germany (12 km resolution). The diagnosed absolute contributions of land transport emissions to reactive nitrogen (NOy) near ground level are in the range of 5 to 10 nmol mol−1. This corresponds to relative contributions of 50 % to 70 %. The largest absolute contributions appear around Paris, southern England, Moscow, the Po Valley, and western Germany. The absolute contributions to carbon monoxide range from 30 nmol mol−1 to more than 75 nmol mol−1 near emission hot-spots such as Paris or Moscow. The ozone which is attributed to land transport emissions shows a strong seasonal cycle with absolute contributions of 3 nmol mol−1 during winter and 5 to 10 nmol mol−1 during summer. This corresponds to relative contributions of 8 % to 10 % during winter and up to 16 % during summer. The largest values during summer are confined to the Po Valley, while the contributions in western Europe range from 12 % to 14 %. Only during summer are the ozone contributions slightly influenced by the anthropogenic emission inventory, but these differences are smaller than the range of the seasonal cycle of the contribution to land transport emissions. This cycle is caused by a complex interplay of seasonal cycles of other emissions (e.g. biogenic) and seasonal variations of the ozone regimes. In addition, our results suggest that during events with large ozone values the ozone contributions of land transport and biogenic emissions increase strongly. Here, the contribution of land transport emissions peaks up to 28 %. Hence, our model results suggest that land transport emissions are an important contributor during periods with large ozone values.

Description: Author(s): Torben Jabben, Norbert Grewe, and Sebastian Schmitt We present an approximation scheme for the treatment of strongly correlated electrons in arbitrary crystal lattices. The approach extends the well-known dynamical mean-field theory to include nonlocal two-site correlations of arbitrary spatial extent. We extract the nonlocal correlation functions fr... [Phys. Rev. B 85, 165122] Published Fri Apr 13, 2012

Description: Author(s): J. H. Thies, D. Frekers, T. Adachi, M. Dozono, H. Ejiri, H. Fujita, Y. Fujita, M. Fujiwara, E.-W. Grewe, K. Hatanaka, P. Heinrichs, D. Ishikawa, N. T. Khai, A. Lennarz, H. Matsubara, H. Okamura, Y. Y. Oo, P. Puppe, T. Ruhe, K. Suda, A. Tamii, H. P. Yoshida, and R. G. T. Zegers A 76 Ge( 3 He, t ) 76 As charge-exchange experiment at an incident energy of 420 MeV has been performed with an energy resolution of 30 keV. The Gamow-Teller GT − strength distribution in 76 As, which is the intermediate nucleus in the double-beta ( β β ) decay of 76 Ge, has been extracted. An unusually strong f... [Phys. Rev. C 86, 014304] Published Tue Jul 03, 2012

Description: Author(s): Sebastian Schmitt, Norbert Grewe, and Torben Jabben [Phys. Rev. B 85, 024404] Published Thu Jan 05, 2012

Description: Author(s): J. H. Thies, T. Adachi, M. Dozono, H. Ejiri, D. Frekers, H. Fujita, Y. Fujita, M. Fujiwara, E.-W. Grewe, K. Hatanaka, P. Heinrichs, D. Ishikawa, N. T. Khai, A. Lennarz, H. Matsubara, H. Okamura, Y. Y. Oo, P. Puppe, T. Ruhe, K. Suda, A. Tamii, H. P. Yoshida, and R. G. T. Zegers The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution ( 3 He, t ) charge-exchange experiment on the double-beta ( β β ) decaying nucleus 100 Mo. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident 3 He beam... [Phys. Rev. C 86, 044309] Published Mon Oct 08, 2012

Description: Author(s): P. Puppe, A. Lennarz, T. Adachi, H. Akimune, H. Ejiri, D. Frekers, H. Fujita, Y. Fujita, M. Fujiwara, E. Ganioğlu, E.-W. Grewe, K. Hatanaka, R. Hodak, C. Iwamoto, N. T. Khai, A. Okamoto, H. Okamura, P. P. Povinec, G. Susoy, T. Suzuki, A. Tamii, J. H. Thies, and M. Yosoi Gamow-Teller (GT) strength distributions have been investigated in a high-resolution ( 3 He, t ) charge-exchange experiment on the double- β ( β β ) decaying nuclei 128 Te and 130 Te. The experiment was carried out at the Research Center for Nuclear Physics, Osaka, with a 420-MeV incident 3 He beam and the Gr... [Phys. Rev. C 86, 044603] Published Mon Oct 01, 2012

Description: Author(s): J. H. Thies, P. Puppe, T. Adachi, M. Dozono, H. Ejiri, D. Frekers, H. Fujita, Y. Fujita, M. Fujiwara, E.-W. Grewe, K. Hatanaka, P. Heinrichs, D. Ishikawa, N. T. Khai, A. Lennarz, H. Matsubara, H. Okamura, Y. Y. Oo, T. Ruhe, K. Suda, A. Tamii, H. P. Yoshida, and R. G. T. Zegers The Gamow-Teller (GT) strength distribution has been investigated in a high-resolution ( 3 He, t ) charge-exchange experiment on the double-beta ( β β ) decaying nucleus 96 Zr. The experiment was carried out at the Osaka University Research Center for Nuclear Physics (RCNP) with a 420 MeV incident 3 He beam ... [Phys. Rev. C 86, 054323] Published Fri Nov 30, 2012

Description: Aviation-attributed climate impact depends on a combination of composition changes in trace gases due to emissions of carbon dioxide (CO2) and non-CO2 species. Nitrogen oxides (NOx = NO + NO2) emissions induce an increase in ozone (O3) and a depletion of methane (CH4), leading to a climate warming and a cooling, respectively. In contrast to CO2, non-CO2 contributions to the atmospheric composition are short lived and are thus characterised by a high spatial and temporal variability. In this study, we investigate the influence of weather patterns and their related transport processes on composition changes caused by aviation-attributed NOx emissions. This is achieved by using the atmospheric chemistry model EMAC (ECHAM/MESSy). Representative weather situations were simulated in which unit NOx emissions are initialised in specific air parcels at typical flight altitudes over the North Atlantic flight sector. By explicitly calculating contributions to the O3 and CH4 concentrations induced by these emissions, interactions between trace gas composition changes and weather conditions along the trajectory of each air parcel are investigated. Previous studies showed a clear correlation between the prevailing weather situation at the time when the NOx emission occurs and the climate impact of the NOx emission. Here, we show that the aviation NOx contribution to ozone is characterised by the time and magnitude of its maximum and demonstrate that a high O3 maximum is only possible if the maximum occurs early after the emission. Early maxima occur only if the air parcel, in which the NOx emission occurred, is transported to lower altitudes, where the chemical activity is high. This downward transport is caused by subsidence in high-pressure systems. A high ozone magnitude only occurs if the air parcel is transported downward into a region in which the ozone production is efficient. This efficiency is limited by atmospheric NOx and HOx concentrations during summer and winter, respectively. We show that a large CH4 depletion is only possible if a strong formation of O3 occurs due to the NOx emission and if high atmospheric H2O concentrations are present along the air parcel's trajectory. Only air parcels, which are transported into tropical areas due to high-pressure systems, experience high concentrations of H2O and thus a large CH4 depletion. Avoiding climate-sensitive areas by rerouting aircraft flight tracks is currently computationally not feasible due to the long chemical simulations needed. The findings of this study form a basis of a better understanding of NOx climate-sensitive areas and through this will allow us to propose an alternative approach to estimate aviation's climate impact on a day-to-day basis, based on computationally cheaper meteorological simulations without computationally expensive chemistry. This comprises a step towards a climate impact assessment of individual flights, here with the contribution of aviation NOx emissions to climate change, ultimately enabling routings with a lower climate impact by avoiding climate-sensitive regions.

Description: This study places HALO research aircraft observations in the upper-tropospheric Asian summer monsoon anticyclone (ASMA) into the context of regional, intra-annual variability by hindcasts with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. The observations were obtained during the Earth System Model Validation (ESMVal) campaign in September 2012. Observed and simulated tracer–tracer relations reflect photochemical O3 production as well as in-mixing from the lower troposphere and the tropopause layer. The simulations demonstrate that tropospheric trace gas profiles in the monsoon season are distinct from those in the rest of the year, and the measurements reflect the main processes acting throughout the monsoon season. Net photochemical O3 production is significantly enhanced in the ASMA, where uplifted precursors meet increased NOx, mainly produced by lightning. An analysis of multiple monsoon seasons in the simulation shows that stratospherically influenced tropopause layer air is regularly entrained at the eastern ASMA flank and then transported in the southern fringe around the interior region. Radial transport barriers of the circulation are effectively overcome by subseasonal dynamical instabilities of the anticyclone, which occur quite frequently and are of paramount importance for the trace gas composition of the ASMA. Both the isentropic entrainment of O3-rich air and the photochemical conversion of uplifted O3-poor air tend to increase O3 in the ASMA outflow.

Description: We quantify the contribution of land transport and shipping emissions to tropospheric ozone for the first time with a chemistry–climate model including an advanced tagging method (also known as source apportionment), which considers not only the emissions of nitrogen oxides (NOx, NO, and NO2), carbon monoxide (CO), and volatile organic compounds (VOC) separately, but also their non-linear interaction in producing ozone. For summer conditions a contribution of land transport emissions to ground-level ozone of up to 18 % in North America and Southern Europe is estimated, which corresponds to 12 and 10 nmol mol−1, respectively. The simulation results indicate a contribution of shipping emissions to ground-level ozone during summer on the order of up to 30 % in the North Pacific Ocean (up to 12 nmol mol−1) and 20 % in the North Atlantic Ocean (12 nmol mol−1). With respect to the contribution to the tropospheric ozone burden, we quantified values of 8 and 6 % for land transport and shipping emissions, respectively. Overall, the emissions from land transport contribute around 20 % to the net ozone production near the source regions, while shipping emissions contribute up to 52 % to the net ozone production in the North Pacific Ocean. To put these estimates in the context of literature values, we review previous studies. Most of them used the perturbation approach, in which the results for two simulations, one with all emissions and one with changed emissions for the source of interest, are compared. For a better comparability with these studies, we also performed additional perturbation simulations, which allow for a consistent comparison of results using the perturbation and the tagging approach. The comparison shows that the results strongly depend on the chosen methodology (tagging or perturbation approach) and on the strength of the perturbation. A more in-depth analysis for the land transport emissions reveals that the two approaches give different results, particularly in regions with large emissions (up to a factor of 4 for Europe). Our estimates of the ozone radiative forcing due to land transport and shipping emissions are, based on the tagging method, 92 and 62 mW m−2, respectively. Compared to our best estimates, previously reported values using the perturbation approach are almost a factor of 2 lower, while previous estimates using NOx-only tagging are almost a factor of 2 larger. Overall our results highlight the importance of differentiating between the perturbation and the tagging approach, as they answer two different questions. In line with previous studies, we argue that only the tagging approach (or source apportionment approaches in general) can estimate the contribution of emissions, which is important to attribute emission sources to climate change and/or extreme ozone events. The perturbation approach, however, is important to investigate the effect of an emission change. To effectively assess mitigation options, both approaches should be combined. This combination allows us to track changes in the ozone production efficiency of emissions from sources which are not mitigated and shows how the ozone share caused by these unmitigated emission sources subsequently increases.