Impacts of horizontal resolution on simulated climate statistics in ECHAM4

The sensitivity of a general circulation model to changes in resolution is studied using the Max Planck Institute for Meteorology (MPI) 19-level model, ECHAM4. Simulations extending over a period between 10 and 15 years, with observed sea surface temperatures as lower boundary conditions from 1979 onward, have been performed using four different horizontal resolutions, T21, T30, T42 and T106. The atmospheric time-mean state and the intraseasonal variability are compared to the European Centre for Medium Range Weather Forecasts (ECMWF) reanalyses and a few other observational datasets. The T30, T42 and T106 simulations are similar in many respects, whereas the T21 simula- tion is qualitatively different. Several effects related to model resolution could be identi- fied, such as increasing tropical upper tropospheric warming with increasing resolution. This is due to more vigorous tropical convection, larger ice water content and, hence, increasing cirrus cloud greenhouse effect. Associated with this increasing warming at higher resolution is a poleward expansion of the zonally averaged circulation regime. On the other hand, the zonally asymmetric component of the circulation, i.e., the stationary waves, improve with higher resolution. Also, higher resolution has a positive impact on regional precipitation patterns which are affected by orography such as the summer mon- soon precipitation over India. Intraseasonal variability has been analyzed only for the higher resolution models, T42 and T106. Compared to the ECMWF reanalyses, both models are able to simulate the intrasea- sonal geopotential height variability, eddy fluxes of heat and momentum, and eddy kinetic energy with reasonable accuracy. This applies to transient eddies in both the bandpass and lowpass regime and to the stationary eddies as well. Some biases can be identified which are more or less independent of resolution. These include the mislocation of the Azores high and the overestimation of its intensity, a cold bias in the polar upper troposphere and lower stratosphere and the poleward and upward displacement of the maxima of geopotential height variability, momentum fluxes and eddy kinetic energy. An important finding is that the operational ECMWF analyses, which have been widely used for model validation, considerably overestimate the lowpass variability, as compared to the reanalyses, due to frequent changes of the forecast model and data assimilation scheme. This implies that the results from our investigations are not directly comparable to previous investigations that used operational analyses for validation

C58 on Au(111): a scanning tunneling microscopy study

C58 fullerenes were adsorbed onto room temperature Au(111) surface by low-energy (~6 eV) cluster ion beam deposition under ultrahigh vacuum conditions. The topographic and electronic properties of the deposits were monitored by means of scanning tunnelling microscopy (STM at 4.2 K). Topographic images reveal that at low coverages fullerene cages are pinned by point dislocation defects on the herringbone reconstructed gold terraces (as well as by step edges). At intermediate coverages, pinned monomers, act as nucleation centres for the formation of oligomeric C58 chains and 2D islands. At the largest coverages studied, the surface becomes covered by 3D interlinked C58 cages. STM topographic images of pinned single adsorbates are essentially featureless. The corresponding local densities of states are consistent with strong cage-substrate interactions. Topographic images of [C58]n oligomers show a stripe-like intensity pattern oriented perpendicular to the axis connecting the cage centers. This striped pattern becomes even more pronounced in maps of the local density of states. As supported by density functional theory, DFT calculations, and also by analogous STM images previously obtained for C60 polymers (M. Nakaya et al., J. Nanosci. Nanotechnol. 11, 2829 (2011)), we conclude that these striped orbital patterns are a fingerprint of covalent intercage bonds. For thick C58 films we have derived a band gap of 1.2 eV from scanning tunnelling spectroscopy data, STS, confirming that the outermost C58 layer behaves as a wide band semiconductor

Impacts of climate change on air pollution levels in the Northern Hemisphere with special focus on Europe and the Arctic

International audienceThe response of a selected number of chemical species is inspected with respect to climate change. The coupled Atmosphere-Ocean General Circulation Model ECHAM4-OPYC3 is providing meteorological fields for the Chemical long-range Transport Model DEHM. Three selected decades (1990s, 2040s and 2090s) are inspected. The 1990s are used as a reference and validation period. In this decade an evaluation of the output from the DEHM model with ECHAM4-OPYC3 meteorology input data is carried out. The model results are tested against similar model simulations with MM5 meteorology and against observations from the EMEP monitoring sites in Europe. The test results from the validation period show that the overall statistics (e.g. mean values and standard deviations) are similar for the two simulations. However, as one would expect the model setup with climate input data fails to predict correctly the timing of the variability in the observations. The overall performance of the ECHAM4-OPYC3 setup as meteorological input to the DEHM model is shown to be acceptable according to the applied ranking method. It is concluded that running a chemical long-range transport model on data from a "free run" climate model is scientifically sound. From the model runs of the three decades, it is found that the overall trend detected in the evolution of the chemical species, is the same between the 1990 decade and the 2040 decade and between the 2040 decade and the 2090 decade, respectively. The dominating impacts from climate change on a large number of the chemical species are related to the predicted temperature increase. Throughout the 21th century the ECHAM4-OPYC3 projects a global mean temperature increase of 3 K with local maxima up to 11 K in the Arctic winter based on the IPCC A2 emission scenario. As a consequence of this temperature increase, the temperature dependent biogenic emission of isoprene is predicted to increase significantly over land by the DEHM model. This leads to an increase in the O3 production and together with an increase in water vapor to an increase in the number of free OH radicals. Furthermore this increase in the number of OH radicals contributes to a significant change in the typical life time of many species, since OH are participating in a large number of chemical reactions. It is e.g. found that more SO42? will be present in the future over the already polluted areas and this increase can be explained by an enhanced conversion of SO2 to SO42?

Permafrost degradation risk zone assessment using simulation models

In this proof-of-concept study we focus on linking large scale climate and permafrost simulations to small scale engineering projects by bridging the gap between climate and permafrost sciences on the one hand and on the other technical recommendation for adaptation of planned infrastructures to climate change in a region generally underlain by permafrost. We present the current and future state of permafrost in Greenland as modelled numerically with the GIPL model driven by HIRHAM climate projections up to 2080. We develop a concept called Permafrost Thaw Potential (PTP), defined as the potential active layer increase due to climate warming and surface alterations. PTP is then used in a simple risk assessment procedure useful for engineering applications. The modelling shows that climate warming will result in continuing wide-spread permafrost warming and degradation in Greenland, in agreement with present observations. We provide examples of application of the risk zone assessment approach for the two towns of Sisimiut and Ilulissat, both classified with high PTP

Moral Damages as an ‘Exceptional’ Remedy in International Investment Law – Re-Connecting Practice with General International Law

Moral damages under international investment law have been extensively addressed in the literature. Notoriously, arbitral tribunals have subjected any claim for moral damages to a requirement unknown to general international law, that is exceptional circumstances. This practice is widely criticised in the field mainly due to the seeming inconsistency with general international law. This article challenges this view by arguing that a deviation from general international law does not – in and of itself – suffice to discard the tribunals’ approach. This argument is based on the insight that general international law only deals with inter-State responsibility and is, thus, open to deviations from general international law in case of State responsibility vis-à-vis the individual. On that basis, the article explores possible legal bases for exceptional circumstances in international law. While it discards the idea that such a requirement for awarding moral damages is implicit in prior inter-State cases, the article rather argues that the arbitral practice witnesses the emergence of a new rule of customary international law applicable to the responsibility of a State vis-à-vis the individual. Thereby, the article seeks to contribute to the wider debate on the content and contours of State responsibility for claims of the individual