Dynamic downscaling of global climate projections for Eastern Europe with a horizontal resolution of 7 km

Climate change is one of the key factors influencing the quantity and quality of water resources in hydrologically sensitive regions. In order to downscale global climate simulations from horizontal resolutions of about 125–200 km to about 7 km, a double nesting strategy was chosen. The modelling approach was implemented with the Regional Climate Model CCLM (COSMO-Climate Local Model) with a first nesting covering a central part of Europe and with a second nesting covering parts of Poland, Belarus, and the Ukraine. A control run—driven by global reanalysis data—was evaluated by comparing the model results with corresponding reference data. Long-term yearly and monthly mean differences of temperature and precipitation were statistically assessed. As reference data for the first nesting, the gridded CRU data set with a horizontal resolution of about 55 km was used. Station data of the NOAA and ECA databases were interpolated to provide an appropriate reference data set for the second nesting. Both nestings overestimated long-term yearly precipitation means. Seasonal evaluation of the first nesting showed positive precipitation biases for spring and winter months and negative biases in summer. Furthermore, differences in the spatial precipitation patterns occured, especially in the high mountain area of the Carpathians. The second nesting overestimated precipitation in spring and summer with smaller biases than in the first nesting. Long-term area means of temperature were properly reproduced. The first nesting showed an overestimation for all months with maximal deviations in summer and spring. In contrast, the second nesting was slightly too warm for summer and autumn and too cold for winter and spring.     

Deep in the Heart of Dixie: Pre-Alleghanian Eclogite and HP Granulite Metamorphism in the Carolina Terrane, South Carolina, USA

The central part of the Carolina terrane in western South Carolina comprises a 30 to 40 km wide zone of high grade gneisses that are distinct from greenschist facies metavolcanic rocks of the Carolina slate belt (to the SE) and amphibolite facies metavolcanic and metaplutonic rocks of the Charlotte belt (to the NW). This region, termed the Silverstreet domain, is characterized by penetratively deformed felsic gneisses, granitic gneisses, and amphibolites. Mineral assemblages and textures suggest that these rocks formed under high‐pressure metamorphic conditions, ranging from eclogite facies through high‐P granulite to upper amphibolite facies. Mafic rocks occur as amphibolite dykes, as metre‐scale blocks of coarse‐grained garnet‐clinopyroxene amphibolite in felsic gneiss, and as residual boulders in deeply weathered felsic gneiss. Inferred omphacite has been replaced by a vermicular symplectite of sodic plagioclase in diopside, consistent with decompression at moderate to high temperatures and a change from eclogite to granulite facies conditions. All samples have been partially or wholly retrograded to amphibolite assemblages. We infer the following P‐T‐t history: (1) eclogite facies P‐T conditions at ≥ 1.4 GPa, 650–730 °C (2) high‐P granulite facies P‐T conditions at 1.2–1.5 GPa, 700–800 °C (3) retrograde amphibolite facies P‐T conditions at 0.9–1.2 GPa and 720–660 °C. This metamorphic evolution must predate intrusion of the 415 Ma Newberry granite and must postdate formation of the Charlotte belt and Slate belt arcs (620 to 550 Ma). Comparison with other medium temperature eclogites and high pressure granulites suggests that these assemblages are most likely to form during collisional orogenesis. Eclogite and high‐P granulite facies metamorphism in the Silverstreet domain may coincide with a ≈570–535 Ma event documented in the western Charlotte belt or to a late Ordovician‐early Silurian event. The occurrence of these high‐P assemblages within the Carolina terrane implies that, prior to this event, the western Carolina terrane (Charlotte belt) and the eastern Carolina terrane (Carolina Slate belt) formed separate terranes. The collisional event represented by these high‐pressure assemblages implies amalgamation of these formerly separate terranes into a single composite terrane prior to its accretion to Laurentia.     

A Clovis well at the type site 11,500 B.C.: The oldest prehistoric well in America

An enigmatic circular pit uncovered during archaeological excavations at the Clovis type site, Blackwater Draw, New Mexico, in 1964 has been reexposed and posited as a water well excavated by Clovis people around 11,500 B.C. The prehistoric well, the oldest in the New World, was probably a dry hole. Other Clovis wells may exist in the area. The excavation of wells near where there had been surface water shortly before adds to the evidence for drought during the Pleistocene-Holocene transition. © 1999 John Wiley & Sons, Inc.