A multi-model ensemble approach for assessment of climate change impact on surface winds in France

Statistical downscaling of 14 coupled atmosphere-ocean general circulation models (AOGCM) is presented to assess potential changes of the 10 m wind speeds in France. First, a statistical downscaling method is introduced to estimate daily mean 10 m wind speed at specific sites using general circulation model output. Daily 850 hPa wind field has been selected as the large scale circulation predictor. The method is based on a classification of the daily wind fields into a few synoptic weather types and multiple linear regressions. Years are divided into an extended winter season from October to March and an extended summer season from April to September, and the procedure is conducted separately for each season. ERA40 reanalysis and observed station data have been used to build and validate the downscaling algorithm over France for the period 1974–2002. The method is then applied to 14 AOGCMs of the coupled model intercomparison project phase 3 (CMIP3) multi-model dataset. Three time periods are focused on: a historical period (1971–2000) from the climate of the twentieth century experiment and two climate projection periods (2046–2065 and 2081–2100) from the IPCC SRES A1B experiment. Evolution of the 10 m wind speed in France and associated uncertainties are discussed. Significant changes are depicted, in particular a decrease of the wind speed in the Mediterranean area. Sources of those changes are investigated by quantifying the effects of changes in the weather type occurrences, and modifications of the distribution of the days within the weather types.     

Dating bedrock gorge incision in the French Western Alps (Ecrins-Pelvoux massif) using cosmogenic 10Be

We report in-situ produced ¹⁰Be data from the Gorge du Diable (French Western Alps) to date and quantify bedrock gorge incision into a glacial hanging valley. We sampled gorge sidewalls and the active channel bed to derive both long-term and present-day incision rates. ¹⁰Be ages of sidewall profiles reveal rapid incision through the late Holocene (ca 5 ka) at rates ranging from 6.5 to 13 mm yr⁻¹. Present-day incision rates are significantly lower and vary from 0.5 to 3 mm yr⁻¹ within the gorge. Our data imply either delayed initiation of gorge incision after final ice retreat from internal Alpine valleys at ca 12 ka, or post-glacial surface reburial of the gorge. Our results suggest that fluvial incision rates >1 cm yr⁻¹ into crystalline bedrock may be encountered in transient landscape features induced by glacial-interglacial transitions.     

Impact structures and events - a Nordic perspective

Impact cratering is one of the fundamental processes in the formation of the Earth and our planetary system, as reflected, for example in the surfaces of Mars and the Moon. The Earth has been covered by a comparable number of impact scars, but due to active geological processes, weathering, sea floor spreading etc, the number of preserved and recognized impact craters on the Earth are limited. The study of impact structures is consequently of great importance in our understanding of the formation of the Earth and the planets, and one way we directly, on the Earth, can study planetary geology.
The Nordic-Baltic area have about thirty confirmed impact structures which makes it one of the most densely crater-populated terrains on Earth. The high density of identified craters is due to the level of research activity, coupled with a deterministic view of what we look for. In spite of these results, many Nordic structures are poorly understood due to the lack of 3D-geophysical interpretations, isotopeor other dating efforts and better knowledge of the amount of erosion and subsequent tectonic modifications.
The Nordic and Baltic impact community is closely collaborating in several impact-related projects and the many researchers （about forty） and PhD students （some seventeen） promise that this level will continue for many more years. The main topics of research include geological, geophysical and geochemical studies in combination with modeling and impact experiments. Moreover, the Nordic and Baltic crust contains some hundred suspect structures which call for detailed analysis to define their origin.
New advanced methods of analyzing geophysical information in combination with detailed geochemical analyses and numerical modeling will be the future basic occupation of the impact scientists of the region. The unique Cretaceous/Tertiary boundary （K-T） occurrences in Denmark form an important source of information in explaining one of the major mass extinctions on Earth.     

High elevation of low‐relief surfaces in mountain belts: does it equate to post‐orogenic surface uplift?

We present experiments of upraising and relaxing topographies showing that peneplanation can occur above the ultimate base level (sea level). After active uplift, the erosion of a topography bounded by a piedmont generates a final smooth and highly elevated topography. Smoothing at high elevation is even possible during active uplift if the evolution of topography is disrupted by the deposition of the products of erosion on its piedmont which is the case at the transition from underfilled to overfilled conditions in foreland basins.     

Tidal and wind-induced circulation within the Southeastern limit of the Bay of Biscay: Pasaia Bay,Basque Coast

The Basque coastal area, in the southeastern Bay of Biscay, can be characterised as being more influenced by land climate and inputs, than other typically ‘open sea’ areas. The influence of coastal processes, together with the presence of irregular and steep topography, complicate greatly the water circulation patterns. Water movement along the Basque coastal area is not well understood; observations are scarce and long-term current records are lacking. The knowledge available is confined to the surface currents: the surface water circulation is controlled mainly by wind forcing, with tidal and density currents being weak. However, there is a lack of knowledge available on currents within the lower levels of the water column; likewise, on the main time-scales involved in the water circulation. This study quantifies the contribution of the tidal and wind-induced currents, to the overall water circulation; it identifies the main time-scales involved within the tidal and wind-induced flows, investigating difference in such currents, throughout the water column, within Pasaia Bay (Basque coast). Within this context, extensive oceanographic and meteorological data have been obtained, in order to describe the circulation. The present investigation reveals that the circulation, within the surface and the sub-surface waters, is controlled mainly by wind forcing fluctuations, over a wide range of meteorological frequencies: third-diurnal, semidiurnal and diurnal land–sea breezes; synoptic variability; frequencies, near fortnightly periods; and seasonal. At the lower levels of the water column, the main contribution to the water circulation arises from residual currents, followed by wind-induced currents on synoptic time-scales. In contrast, tidal currents contribute minimally to the overall circulation throughout the water column.     

Erweiterte Grundgleichungen zur Bestimmung der Verdunstung auf dem Meer aus dem klein- und großräumigen Feuchteaustausch

Zusammenfassung Es wird eine anwendbare Verallgemeinerung der Konzeptionen angestrebt, nachdenen man die Verdunstung auf dem Meere aus dem atmosphärischen Wasseraustausch bestimmt. Dabei ergeben sich einige Hinweise auf mehrere übliche aber kaum erkannte Vernachlässigungen. Unteranderem werden die Effekte der Druckänderungen sowie — durch Anwendung abgewogener Mittelwerte — die Wirkung des fluktuativen Massentransports in Rechnung gestellt. Jene werden meist in Makroturbulenzbetrachtungen, diese in Mikroturbulenzbetrachtungen zum Feuchteaustausch vernachlässigt, obgleich sie die Größenordnung der berechneten Verdunstungswerte erreichen und beispielsweise zur Erklärung der bei labiler Schichtung beobachteten deutlichen Verschiedenheit der gebräuchlichen Austauschkoeffizienten für Wasserdampf und Wärme beitragen können.

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Extended basic equations concerning the estimation of evaporation on the ocean from small- and large-scale exchange of moisture

Summary This paper aims at an applicable generalisation of the conceptions adapted to the estimation of evaporation on the ocean from theaustausch of water in the atmosphere. It gives some hints to several common but scarcely known neglects. Among others, the effects of the variation of pressure, and — by applying weighted means — those of the fluctuative transport of mass are taken into account. Usually the first effects are neglected in considerations on large-scale exchange of atmospheric water, the second ones in small-scale considerations although they may be of the same order of magnitude as the computed evaporation and may be able, for instance, to support an interpretation of the distinct inequalities of the usual eddy transfer coefficients of water vapour and heat observed in unstable lapse conditions.

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Equations fondamentales étendues pour dériver du flux micro- et macroturbulent de l'humidité l'évaporation à la surface de la mer

Résumé Le but de ce travail est de trouver une généralisation applicable des conceptions employées à dériver de l'échange atmosphérique de l'eau l'évaporation à la surface de la mer. Au cours de ces recherches on rencontre plusieurs indications de diverses négligences en usage qui, cependant, ne sont guère reconnues. Entre autre, on tient compte des effets dus aux variations de la pression atmosphérique et — en appliquant des moyennes pondérées — on considère également l'action du transport fluctuatif de la masse. Conventionnellement, le premier effet est négligé dans des considérations à base macroturbulente pendant que le deuxième effet est laissé de côté en cas de la diffusion microturbulente, bien que ces deux effets puissent atteindre la même ordre de grandeur que l'évaporation calculée et qu'ils puissent, par exemple, aider à expliquer les diversités distinctes des coefficients d'échange de l'humidité et de la chaleur observées quand la répartition des masses suivant la verticale est instable.

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Für Anregungen und die Möglichkeit zur Bearbeitung der diskutierten Fragen ist der Verfasser Herrn Professor Dr. Hermann Flohn zu Dank verpflichtet.     

Survival,duration of larval stages,and size of postlarvae of grass shrimp,Palaemonetes pugio,reared from kepone® contaminated and uncontaminated populations in Chesapeake Bay

Replicate groups of larvae from each of three female grass shrimp,Palaemonetes pugio, collected at each of six sites within Chesapeake Bay were reared in the laboratory to metamorphosis at 25°C, 25 ppt salinity. They were provided with approximately 300Artemia nauplii/larva/day. Sites were selected to provide both suspected Kepone^® contaminated and non-contamined shrimp populations. A sample of eggs, adult females with and without eggs, and newly hatched larvae from each site were analyzed by Virginia Institute of Marine Science for Kepone as were postlarvae obtained through laboratory rearings. Females and eggs from the James River had highest concentrations of Kepone (0.63 and 0.47 ppm, respectively) with samples from the Lafayette River at the mouth of the James River having the second highest levels (0.04 and 0.4 ppm). Concentrations in ovigerous females and eggs in the populations most distant from the James (mouth of Potomac and upper Potomac River) were at or below the limits of detectability (0.001 to 0.015 ppm). In laboratory reared postlarvae from each site, concentrations of Kepone were undetectable. Despite these apparent differences in Kepone concentrations in the various populations we found no significant differences in larval survival, larval duration, or length of post-larvae attributable to site of origin. Highly significant differences in larval duration and size of post-larvae were attributable to parental variation.