Holocene climate in the subarctic fjord Malangen, northern Norway: a multi-proxy study

A Holocene sedimentary record from the deep-silled Malangen fjord in northern Norway reveals regional changes in sedimentary environment and climate. Down-core analysis of two sediment cores includes multi-core sensor logging, grain size, x-radiography, foraminifera, oxygen isotopes, dinoflagellates, pollen, trace elements and radiocarbon datings. The cores are located just proximal to the submarine Younger Dryas moraine complex, and reveal the deglaciation after Younger Dryas and the postglacial evolution. Five sedimentary units have been identified. The oldest units, V and IV, bracket the Younger Dryas glacial readvance in the fjord between 12 700 cal. years BP and 11 800 cal. years BP. This is followed by deposition of glaciomarine sediments (units IV and III) starting around 12 100 cal. years BP. Glaciomarine sedimentation ceased in the fjord c. 10 300 cal. years BP and was replaced by open marine sedimentation (units II and I). A rapid stepwise warming occurred during the Preboreal. Onset of surface water warming lagged bottom water warming by several hundred years. The δ[Formula: See Text]O record indicates a significant, gradual bottom water cooling (c. 4°C) between 8000 and 2000 cal. years BP, a trend also supported by the other proxy data. Other records in the region, as well as GCM simulations, also support this long-term climatic evolution. Superimposed on this cooling were brief warmings around 6000 cal. years BP and 2000 cal. years BP. The long-term change may be driven by orbitally forced reduction in insolation, whereas the short-term changes may be linked to for example solar forcing, meltwater and NAO changes all causing regional changes in the North Atlantic heat transport.     

POPULATION AND RESOURCES IN TWO TYPES OF RURAL LANDSCAPE

Mørch, Henning: Population and resources in two types of rural landscape—Denmark 1860, 1900, and 1960. Geografisk Tidsskrift 80: 88–92. Copenhagen, June 1980.

An investigation on the basis of simple, linear regression of the relationship between size of population and physical resources in two types of landscape—moraine and outwash plain—Denmark 1860–1960.     

Prediction uncertainty of conceptual rainfall-runoff models caused by problems in identifying model parameters and structure

Abstract

The uncertainties arising from the problem of identifying a representative model structure and model parameters in a conceptual rainfall-runoff model were investigated. A conceptual model, the HBV model, was applied to the mountainous Brugga basin (39.9 km”) in the Black Forest, southwestern Germany. In a first step, a Monte Carlo procedure with randomly generated parameter sets was used for calibration. For a ten-year calibration period, different parameter sets resulted in an equally good correspondence between observed and simulated runoff. A few parameters were well defined (i.e. best parameter values were within small ranges), but for most parameters good simulations were found with values varying over wide ranges. In a second step, model variants with different numbers of elevation and landuse zones and various runoff generation conceptualizations were tested. In some cases, representation of more spatial variability gave better simulations in terms of discharge. However, good results could be obtained with different and even unrealistic concepts. The computation of design floods and low flow predictions illustrated that the parameter uncertainty and the uncertainty of identifying a unique best model variant have implications for model predictions. The flow predictions varied considerably. The peak discharge of a flood with a probability of 0.01 year^?1, for instance, varied from 40 to almost 60 mm day^?1. It was concluded that model predictions, particularly in applied studies, should be given as ranges rather than as single values.     

Infrared,ultraviolet, and electron paramagnetic resonance measurements on presolar diamonds: Implications for optical features and origin

Abstract— Infrared (IR) and ultraviolet (UV) absorption spectra were obtained for diamonds from the Allende and Murchison meteorites. In addition, and for the first time, electron paramagnetic resonance spectra were measured. The IR and UV data confirm the suspicion of Russell et al. (1996) that N in presolar diamonds predominantly appears in the form of dispersed N atoms, as is the case for terrestrial type Ib diamonds. In accordance with other observations, our electron paramagnetic resonance measurements suggest a high H content in presolar diamonds. The presolar diamonds most likely originated in a H‐rich region, an environment in which nanometer‐sized diamonds may be more stable than graphite (Badziag et al., 1990). This adds to the evidence—previously based mainly on the twin microstructures of presolar diamonds (Daulton et al., 1996) and the absence of graphite with the same isotopic composition as presolar diamonds (Anders and Zinner, 1993)—for a homogeneous nucleation of presolar diamonds from a gas phase. Based on our results for detection of diamonds in space, we suggest searching for the N‐induced IR and UV absorption features of type Ib diamonds. Other characteristic diamond features that could also be used to detect diamonds in space are the (‐CH_n) IR absorption features due to H‐coated diamonds, as they are described by Allamandola et al. (1993) and the IR multiphonon absorption features of the diamond lattice. The multiphonon features are very weak (Edwards, 1985), but their intensity increases somewhat with increasing temperature (Collins and Fan, 1954), so perhaps a search for them is not totally hopeless.     

A Late Pleistocene sequence at Seitevare, Swedish Lapland

A peat layer beneath two till beds was found at Seitevare in Swedish Lapland. The pollen flora layer indicates deposition during the later part of the Eemian Interglacial. The vegetation consisted of open forests predominated by pine and birch, mixed with alder and spruce. The sedimentation took place in a small oligotrophic-dystrophic water basin with a pH about 5, according to the diatom flora. In an adjacent section, silty sediments with pollen indicating interstadial vegetation (birches, herbs) are covered by one till bed. These sediments are tentatively correlated with the Peräpohjola Interstadial in northern Finland and north-eastern Sweden. The lithostratigraphy indicates one pre-Eemian and probably three Weichselian glacial advances.