Holocene climatic change and the development of the lake-effect snowbelt in Michigan, USA

Lake-effect snow is an important constraint on ecological and socio-economic systems near the North American Great Lakes. Little is known about the Holocene history of lake-effect snowbelts, and it is difficult to decipher how lake-effect snowfall abundance affected ecosystem development. We conducted oxygen-isotope analysis of calcite in lake-sediment cores from northern Lower Michigan to infer Holocene climatic variation and assess snowbelt development. The two lakes experience the same synoptic-scale climatic systems, but only one of them (Huffman Lake) receives a significant amount of lake-effect snow. A 177-cm difference in annual snowfall causes groundwater inflow at Huffman Lake to be 18O-depleted by 2.3��� relative to O'Brien Lake. To assess when the lake-effect snowbelt became established, we compared calcite-��18O profiles of the last 11,500 years from these two sites. The chronologies are based on accelerator-mass-spectrometry 14C ages of 11 and 17 terrestrial-plant samples from Huffman and O'Brien lakes, respectively. The values of ��18O are low at both sites from 11,500 to 9500 cal yr BP when the Laurentide Ice Sheet (LIS) exerted a dominant control over the regional climate and provided periodic pulses of meltwater to the Great Lakes basin. Carbonate ��18O increases by 2.6��� at O'Brien Lake and by 1.4��� at Huffman Lake between 9500 and 7000 cal yr BP, suggesting a regional decline in the proportion of runoff derived from winter precipitation. The Great Lakes snowbelt probably developed between 9500 and 5500 cal yr BP as inferred from the progressive 18O-depletion at Huffman Lake relative to O'Brien Lake, with the largest increase of lake-effect snow around 7000 cal yr BP. Lake-effect snow became possible at this time because of increasing contact between the Great Lakes and frigid arctic air. These changes resulted from enhanced westerly flow over the Great Lakes as the LIS collapsed, and from rapidly rising Great Lakes levels during the Nipissing Transgression. The ��18O difference between Huffman and O'Brien lakes declines after 5500 cal yr BP, probably because of a northward shift of the polar vortex that brought increasing winter precipitation to the entire region. However, ��18O remains depleted at Huffman Lake relative to O'Brien Lake because of the continued production of lake-effect snow.

Footprint of recycled water subsidies downwind of Lake Michigan

Continental evaporation is a significant and dynamic flux within the atmospheric water budget, but few methods provide robust observational constraints on the large-scale hydroclimatological and hydroecological impacts of this ���recycled-water' flux. We demonstrate a geospatial analysis that provides such information, using stable isotope data to map the distribution of recycled water in shallow aquifers downwind from Lake Michigan. The ��2H and ��18O values of groundwater in the study region decrease from south to north, as expected based on meridional gradients in climate and precipitation isotope ratios. In contrast, deuterium excess (d = ��2H ��� 8 �� ��18O) values exhibit a significant zonal gradient and finer-scale spatially patterned variation. Local d maxima occur in the northwest and southwest corners of the Lower Peninsula of Michigan, where ���lake-effect' precipitation events are abundant. We apply a published model that describes the effect of recycling from lakes on atmospheric vapor d values to estimate that up to 32% of recharge into individual aquifers may be derived from recycled Lake Michigan water. Applying the model to geostatistical surfaces representing mean d values, we estimate that between 10% and 18% of the vapor evaporated from Lake Michigan is re-precipitated within downwind areas of the Lake Michigan drainage basin. Our approach provides previously unavailable observational constraints on regional land-atmosphere water fluxes in the Great Lakes Basin and elucidates patterns in recycled-water fluxes that may influence the biogeography of the region. As new instruments and networks facilitate enhanced spatial monitoring of environmental water isotopes, similar analyses can be widely applied to calibrate and validate water cycle models and improve projections of regional hydroecological change involving the coupled lake-atmosphere-land system. Read More: http://www.esajournals.org/doi/abs/10.1890/ES12-00062.1

Toleranz und Humanit��t, ein Wort der Abwehr und Verst��ndigung : im Jahre 1859

von [Josef] Aub

A catalog of high-impact windstorms in Switzerland since 1859

In recent decades, extremely hazardous windstorms have caused enormous losses to buildings, infrastructure and forests in Switzerland. This has increased societal and scientific interest in the intensity and frequency of historical high-impact storms. However, high-resolution wind data and damage statistics mostly span recent decades only. For this study, we collected quantitative (e.g., volumes of windfall timber, losses relating to buildings) and descriptive (e.g., forestry or insurance reports) information on the impact of historical windstorms. To define windstorm severity, normalized and declustered quantitative data were processed by extreme value statistics. Descriptive information was classified using a conceptual guideline. Validation with independent damage information, as well as comparison with wind measurements and a reanalysis, indicates that the most hazardous winter storms are captured, while too few moderate windstorms are detected. Strong storms in the wind measurements and reanalysis are thus added to the catalog. The final catalog encompasses approximately 240 high-impact windstorms in Switzerland since 1859. It features three robust severity classes and contains eight extreme windstorms. Evidence of high winter storm activity in the early and late 20th century compared to the mid-20th century in both damage and wind data indicates a co-variability of hazard and related damage on decadal timescales.

Die letzte Versammlung im alten und die erste Versammlung im neuen Gotteshause : zwei Vortr��ge vor und zur Einweihung der neuen Synagoge zu Wolfhagen am 28. Tischri 5620 (26. October 1859)

gehalten von L. Adler

Die Feier der Einweihung der neuen Synagoge zu Trier, am 9. - 10. September 1859 - 10. - 11. Ellul 5619 : enth.: Erkl��rung d. hebr. Inschriften, Gebete u. Reden, nebst e. Beschreibung d. neuen Synagoge in Trier

von Chr. Schmidt. Hrsg. von J. Kahn

Ma tobu : Festkl��nge zur Feier der Einweihung des neuerbauten isr. Cultus-Tempels zu Pest im September 1859

von L. M. Bauer