COMPARISON OF A HIGH-RESOLUTION REGIONAL SIMULATION AND THE ERA40 REANALYSIS OVER THE ALPINE REGION

Within the EU project ALP-IMP a high-resolution regional simulation driven by the ERA40 reanalysis has been performed for the Greater Alpine Region (GAR) for the period 1958 to the present. A comparison of the high-resolution simulation and the ERA40 reanalysis regridded to 1 deg resolution with four different monthly mean temperature datasets for the GAR shows for both very high correlations of around 0.9, and in general slightly higher correlations for the regional simulation. Correlations of the regional simulation and the reanalysis with observations increase with spacial scale. The separation of the GAR into six subregions identifies the Po plain as a region where the high-resolution simulation as well as ERA40 have problems in reproducing the instrumental measurements

COMPARISON OF A HIGH-RESOLUTION REGIONAL SIMULATION AND THE ERA40 REANALYSIS OVER THE ALPINE REGION

Within the EU project ALP-IMP a high-resolution regional simulation driven by the ERA40 reanalysis has been performed for the Greater Alpine Region (GAR) for the period 1958 to the present. A comparison of the high-resolution simulation and the ERA40 reanalysis regridded to 1 deg resolution with four different monthly mean temperature datasets for the GAR shows for both very high correlations of around 0.9, and in general slightly higher correlations for the regional simulation. Correlations of the regional simulation and the reanalysis with observations increase with spacial scale. The separation of the GAR into six subregions identifies the Po plain as a region where the high-resolution simulation as well as ERA40 have problems in reproducing the instrumental measurements

MiKlip - a National Research Project on Decadal Climate Prediction

A German national project coordinates research on improving a global decadal climate prediction system for future operational use. MiKlip, an eight-year German national research project on decadal climate prediction, is organized around a global prediction system comprising the climate model MPI-ESM together with an initialization procedure and a model evaluation system. This paper summarizes the lessons learned from MiKlip so far; some are purely scientific, others concern strategies and structures of research that targets future operational use. Three prediction-system generations have been constructed, characterized by alternative initialization strategies; the later generations show a marked improvement in hindcast skill for surface temperature. Hindcast skill is also identified for multi-year-mean European summer surface temperatures, extra-tropical cyclone tracks, the Quasi-Biennial Oscillation, and ocean carbon uptake, among others. Regionalization maintains or slightly enhances the skill in European surface temperature inherited from the global model and also displays hindcast skill for wind-energy output. A new volcano code package permits rapid modification of the predictions in response to a future eruption. MiKlip has demonstrated the efficacy of subjecting a single global prediction system to a major research effort. The benefits of this strategy include the rapid cycling through the prediction-system generations, the development of a sophisticated evaluation package usable by all MiKlip researchers, and regional applications of the global predictions. Open research questions include the optimal balance between model resolution and ensemble size, the appropriate method for constructing a prediction ensemble, and the decision between full-field and anomaly initialization. Operational use of the MiKlip system is targeted for the end of the current decade, with a recommended generational cycle of two to three years

Environmental heterogeneity predicts species richness of freshwater mollusks in sub-Saharan Africa

Species diversity and how it is structured on a continental scale is influenced by stochastic, ecological, and evolutionary driving forces, but hypotheses on determining factors have been mainly examined for terrestrial and marine organisms. The extant diversity of African freshwater mollusks is in general well assessed to facilitate conservation strategies and because of the medical importance of several taxa as intermediate hosts for tropical parasites. This historical accumulation of knowledge has, however, not resulted in substantial macroecological studies on the spatial distribution of freshwater mollusks. Here, we use continental distribution data and a recently developed method of random and cohesive allocation of species distribution ranges to test the relative importance of various factors in shaping species richness of Bivalvia and Gastropoda. We show that the mid-domain effect, that is, a humpshaped richness gradient in a geographically bounded system despite the absence of environmental gradients, plays a minor role in determining species richness of freshwater mollusks in sub-Saharan Africa. The western branch of the East African Rift System was included as dispersal barrier in richness models, but these simulation results did not fit observed diversity patterns significantly better than models where this effect was not included, which suggests that the rift has played a more complex role in generating diversity patterns. Present-day precipitation and temperature explain richness patterns better than Eemian climatic condition. Therefore, the availability of water and energy for primary productivity during the past does not influence current species richness patterns much, and observed diversity patterns appear to be in equilibrium with contemporary climate. The availability of surface waters was the best predictor of bivalve and gastropod richness. Our data indicate that habitat diversity causes the observed species–area relationship, and hence, that environmental heterogeneity is a principal driver of freshwater mollusk richness on a continental scale

Representation of the Antarctic Oscillation and related precipitation patterns in the MPI Earth System Model

The Antarctic Oscillation (AAO) is the dominant mode of atmospheric variability in the southern hemisphere. It is obtained via a principal component analysis (PCA) for geopotential height anomalies. Being the southern hemisphere's dominant mode, an adequate representation in earth system models is desirable. This paper evaluates to what extent the AAO and related precipitation is represented in the Max Planck Institute's Earth System Model (MPI-ESM). To this end we compare AAO spatial patterns (empirical orthogonal functions, EOFs), spectral properties of the associated principal components (PCs) and AAO-related precipitation patterns of MPI-ESM to three reanalyses: the ECMWF's ERA-40 and ERA-Interim, and the NCEP/NCAR 40-year reanalysis project. Differences between MPI-ESM and ERA-Interim leading EOFs reveal that the three typical centres of action are less pronounced and slightly shifted in the model. Spectral density estimates of the associated PCs show reduced variability in the MPI-ESM for periods between 4 to 5 months. The relation between AAO and southern hemispheric precipitation is assessed via composites and correlation analysis. In both, model and reanalyses, a negative AAO index leads to a general increase of precipitation between 30° S and 50° S and a decrease south of 50° S. Differences between maps of correlation for AAO and precipitation are most prominent near Indonesia and Antarctica probably due to a lack of pressure around Antarctica in the model. Altogether the MPI-ESM underestimates the relation of AAO and southern hemispheric precipitation but gives the correct sign and spatial distribution of correlation values