Heavy rains and extreme rainfall-runoff events in Central Europe from 1951 to 2002

Runoff data were used to better select historically significant precipitation events. The suggested criterion <i>Q<sub>x</sub></i> expresses the increase of a stream runoff over up to four days in a row. Tests confirmed that <i>Q<sub>x</sub></i> maxima correspond to maxima of areal precipitation in the respective catchment. Ten significant precipitation events in summer half-years from 1951 to 2002 were selected in 25 catchments each, and further studied in respect to spatial extent, simultaneous occurrence in various river basins, seasonal distribution, and temporal variability. Four regions were recognised within Central Europe that show related seasonality and simultaneous occurrence of events. The main coincidence of significant precipitation events was confirmed between the Austrian Alps and Bohemia and Saxony on one hand, and Moravia, Silesia, and Western Slovakia on the other hand. Significant events typically emerge here during peak summer, in the south-eastern area of the Alps during autumn months, in the South-Eastern Carpathians from May to July, and in Western Germany in spring or autumn. Episodes with less significant precipitation events (around 1960 and 1990) alternate with inverse episodes (1970's, second half of the 1990's). A reasonable selection of reference events opens the door to a quantitative evaluation of dynamic and thermodynamic conditions typical for heavy rains in various parts of Central Europe

Vegetation greenness in northeastern Brazil and its relation to ENSO warm events

The spatio-temporal variability of trends in vegetation greenness in dryland areas is a well-documented phenomenon in remote sensing studies at global to regional scales. The underlying causes differ, however, and are often not well understood. Here, we analyzed the trends in vegetation greenness for a semi-arid area in northeastern Brazil (NEB) and examined the relationships between those dynamics and climate anomalies, namely the El Nino Southern Oscillation (ENSO) for the period 1982 to 2010, based on annual Normalized Difference Vegetation Index (NDVI) values from the latest version of the Global Inventory Modeling and Mapping Studies (GIMMS) NDVI dataset (NDVI3g) dataset. Against the ample assumption of ecological and socio-economic research, the results of our inter-annual trend analysis of NDVI and precipitation indicate large areas of significant greening in the observation period. The spatial extent and strength of greening is a function of the prevalent land-cover type or biome in the study area. The regression analysis of ENSO indicators and NDVI anomalies reveals a close relation of ENSO warm events and periods of reduced vegetation greenness, with a temporal lag of 12 months. The spatial patterns of this relation vary in space and time. Thus, not every ENSO warm event is reflected in negative NDVI anomalies. Xeric shrublands (Caatinga) are more sensitive to ENSO teleconnections than other biomes in the study area.JRC.H.4-Monitoring Agricultural Resource

Blitzaufkommen im Freistaat Sachsen

Sachsen gehört zu den gewitter- und blitzreichsten Regionen Deutschlands. Durchschnittlich werden hier etwa 3,5 Blitze pro km² und Jahr gemessen (in Thüringen etwa 1,5 Blitze). Gewitter und Blitzaktivitäten bergen hohe Risiken für Umwelt und Gesellschaft. Bedeutend sind dabei die Stromstärke, die Anzahl der Blitze und Begleiterscheinungen wie Hagel, Windböen oder Starkregen. Die Studie umfasste eine grundlegenden Analyse der Blitzaktivitäten in Sachsen. Die Beobachtungsdaten seit 1999 belegen Trends zur Zunahme der Blitzhäufigkeit pro Tag und den Einfluss westlicher, südwestlicher und südlicher Anströmungen auf die Blitzaktivität. Für den Beobachtungszeitraum werden hohe jährliche Variabilitäten aufgezeigt. Offenkundige Zusammenhänge zwischen Blitzaktivität und Landnutzung bzw. Klimaparametern sind bisher nicht erkennbar. Für die Zukunft ist aber die Beeinflussung der Gewitterhäufigkeit durch die Erwärmung der Atmosphäre nicht auszuschließen

GEMAS: CNS concentrations and C/N ratios in European agricultural soil

A reliable overview of measured concentrations of TC, TN and TS, TOC/TN ratios, and their regional distribution patterns in agricultural soil at the continental scale and based on measured data has been missing – despite much previous work on local and the European scales. Detection and mapping of natural (ambient) background element concentrations and variability in Europe was the focus of this work. While total C and S data had been presented in the GEMAS atlas already, this work delivers more precise (lower limit of determination) and fully quantitative data, and for the first time high-quality TN data

Particle number size distributions in urban air before and after volatilisation

Aerosol particle number size distributions (size range 0.003–10 μm) in the urban atmosphere of Augsburg (Germany) were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm−3, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass. Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C), allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R2=0.9) suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could be determined as a function of particle size. The results indicated that particles >60 nm contain a significantly higher fraction of non-volatile compounds, most likely black carbon, than particles <60 nm. The results are relevant for future health-related studies in that they explore the size distribution and time-dependent behaviour of the refractory component of the urban aerosol over an extended time period

Abschätzung der größenaufgelösten Partikelkonzentration und -zusammensetzung anhand wetterlagenorientierter experimenteller Messungen

Der Bericht "Abschätzung der größenaufgelösten Partikelkonzentration und -zusammensetzung anhand wetterlagenorientierter experimenteller Messungen" repräsentiert das REGKLAM-Produkt 2.2b. Auf der Grundlage von Experimenten wurde die heutige Situation analysiert und Szeanarien für einen Temperaturanstiegt sowie für eine Änderung der Anströmcharakteristik erarbeitet. Da die PM10-Massenkonzentrationen bereits heute Grenzwerte überschreiten und im Rahmen der klimatischen Veränderung nicht mit einer wesentlichen Abnahme zu rechnen ist, bleibt es auch zukünftig eine wichtige Herausforderung, die Emissionen von Partikeln und deren Vorläufersubstanzen sowohl in der Stadt als auch in der großräumigen Umgebung zu vermeiden

Bodenatmung (CO2, CH4, N2O), Landnutzung und Klima am Beispiel Amazonasbecken.

Klima und Menschleit. Kolloquium am 14. April 2016

Modelling trace metal background to evaluate anthropogenic contamination in arable soils of south-western France

The trace metal (TM) content in arable soils has been monitored across a region of France characterised by a large proportion of calcareous soils. Within this particular geological context, the objectives were to first determine the natural levels of trace metals in the soils and secondly, to assess which sites were significantly contaminated. Because no universal contamination assessment method is currently available, four different methods were applied and compared in order to facilitate the best diagnosis of contamination. First, the TM geochemical background was determined by using basic descriptive statistics and linear regression models calculated with semi-conservative major elements as predictors. The natural concentrations of trace metals varied greatly due to the high soil heterogeneity encountered on the regional scale and were more-or-less accurately modelled according to the considered TM. Second, the basic descriptive statistics and the linear regression methods were then compared with the enrichment factor (EF) method and multivariate analysis (PCA), in order to evaluate whether the concentrations measured in soils were abnormally high or not. The advantages and disadvantages of each method were discussed and their results used to identify the most probable contamination cases, the influence of the soils characteristics, as well as the agricultural land cover. The basic descriptive method was good as a first and easy approach to describe the TM ambient concentrations, but may misinterpret the natural anomalies as contaminations. Based on geochemical associations, the linear regression method provided more realistic results even if the relationships between major and trace metals were not significant for the most mobile TM. The EF method was useful to identify high point source contaminations, but it was not suitable when considering a large dataset of low TM concentrations. Finally, the PCA method was a good preliminary tool for the description of the global TM concentrations in a studied area, but it could only give indication on the highest contaminated points. By comparing the results of the different methods in the studied region, we estimated that 24% of the arable soils were contaminated by at least one trace metal, mainly Cu in vineyards/orchards and Cd, Pb and/or Zn in grazing lands. In addition, the calcareous soils exhibited globally higher natural and anthropogenic TM concentrations than non-calcareous soils, probably because of the lower TM mobility at alkaline pH