Drifting runoff periodicity during the 20th century due to changing surface water volume

Fourier and wavelet analyses were used to reveal the dominant trends and coherence of a more than one‐century‐long time series of precipitation and discharge in several watersheds in Sweden, two of which were subjected to hydropower and intensive agriculture. During the 20th century, there was a gradual, significant drift of the dominant discharge periodicity in agricultural watersheds. This study shows that the steepness of the Fourier spectrum of runoff from the May to October period each year increased gradually during the century, which suggests a more predictable intra‐annual runoff pattern (more apart from white‐noise). In the agricultural watershed, the coherence spectrum of precipitation and runoff is generally high with a consistent white‐noise relationship for precipitation during the 20th century, indicating that precipitation is not controlling the drift of the discharge spectrum. In the hydropower regulated watershed, there was a sudden decrease of the discharge spectrum slope when regulation commenced in the 1920s. This study develops a new theory in which the runoff spectrum is related to the hydraulic and hydro‐morphological characteristics of the watershed. Using this theory, we explain the changes in runoff spectra in the two watersheds by the anthropogenic change in surface water volume and, hence, changes in kinematic wave celerity and water transit times. The reduced water volume in the agricultural watershed would also contribute to decreasing evaporation, which could explain a slightly increasing mean discharge during the 20th century despite the fact that precipitation was statistically constant in the area. Copyright © 2010 John Wiley & Sons, Ltd.     

Capturing the stories of corporations: A comparison of media debates on carbon capture and storage in Norway and Sweden

The development and deployment of carbon capture and storage (CCS) are sensitive to public debates that socially frame the technology. This study examines the evolving CCS debates, focusing on the media's framing of firms. Corporations are central CCS actors, and we analyze them in light of the nation-state, which has been emphasized in previous research as the primary context of CCS politics. Empirically, we compare framings of Statoil and Vattenfall in the Norwegian and Swedish media, drawing on a qualitative dataset of news media articles published between 2005 and 2009. We conclude that firms make regular media statements either to foster legitimacy or to respond to criticism of CCS. We also conclude that framing is not necessarily linked to technological success or failure and that interpretations of the technology have different forms depending on whether the related activity occurs in domestic or foreign markets. Finally, we explain the media framings based on the domestic energy situation and politics.     

Temporal and life history related trends of perfluorochemicals in harbor porpoises from the Danish North Sea

Eighty-five stranded or bycaught harbor porpoises collected from the Danish North Sea between 1980 and 2005 were analyzed for perfluorochemicals in the liver. PFOS was the predominant compound, making up on average 88.9% of the ∑PFC, followed by PFOSA (7.8%). PFUnA (1.9%) and PFDA (1.2%) were detected in most samples. PFHxS, PFNA and PFOA were only found in a minority of the samples. We found substantial differences in PFC concentrations among life history stages, the highest concentrations were found in neonates, suckling juveniles and lactating females. Such differences should be considered when PFC levels in wildlife are evaluated. The high concentrations found in young porpoises are of concern as PFCs have known toxic effects on the development of the central nervous system and reproductive organs. Despite efforts to reduce PFC emissions, a decreasing temporal trend of concentrations was not detected for any compound. PFCA concentrations were found to be increasing.     

Empirical models of monthly and annual albedo in managed boreal forests of interior Norway

An 11-year remotely sensed surface albedo dataset coupled with historical meteorological and stand-level forest management data for a variety of stands in Norway’s most productive logging region is used to develop regression models describing temporal changes in forest albedo following clear-cut harvest disturbance events. Datasets are grouped by dominant tree species, and two alternate multiple regression models are developed and tested following a potential-modifier approach. This result in models with statistically significant parameters (p?<?0.05) that explain a large proportion of the observed variation, requiring a single canopy modifier predictor coupled with either monthly or annual mean air temperature as a predictor of a stand’s potential albedo. Models based on annual mean temperature predict annual albedo with errors (RMSE) in the range of 0.025–0.027, while models based on monthly mean temperature predict monthly albedo with errors ranging between of 0.057–0.065 depending on the dominant tree species. While both models have the potential to be transferable to other boreal regions with similar forest management regimes, further validation efforts are required. As active management of boreal forests is increasingly seen as a means to mitigate climate change, the presented models can be used with routine forest inventory and meteorological data to predict albedo evolution in managed forests throughout the region, which, together with carbon cycle modeling, can lead to more holistic climate impact assessments of alternative forest harvest scenarios and forest product systems.     

Mantle material in the main belt: Battered to bits?

Abstract— The complete (or near complete) differentiation of a chondritic parent body is believed to result in an object with an Fe-Ni core, a thick olivine-dominated mantle and a thin plagioclase/pyroxene crust. Compositional groupings of iron meteorites give direct evidence that at least 60 chondritic parent bodies have been differentiated and subsequently destroyed. A long standing problem has been that our meteorite collections, and apparently our asteroid observations as well, show a great absence of olivine-dominated metal-free mantle material. While the basaltic achondrites (HED meteorites) represent metal-free pyroxene-dominated crustal samples, the isotopic and geochemical evidence implies that this class is derived from only one parent body (perhaps Vesta). Thus the meteoritic (and perhaps astronomical) evidence also suggests a great absence of crustal material resulting from the collisional disruption of numerous parent bodies. One explanation for the rarity of olivine-dominated metal-free and basaltic asteroids that fits all the available evidence is that all differentiated parent bodies, with the exception of Vesta, were either disrupted or had their crusts and mantles stripped very early in the age of the solar system. The resulting basaltic and olivine-dominated metal-free fragments were continually broken down until their sizes dropped at least below our current astronomical measurement limit (～5–10 km for inner-belt objects) and perhaps completely comminuted such that meteorite samples are no longer delivered. Because of their greater strengths and longer survival time in interplanetary space, only the iron and the stony-iron meteorites remain as the final tracers of this differentiation and collisional history. However, other scenarios remain plausible such as those which invoke “space weathering” processes that effectively disguise the distinctive basaltic and olivine spectra of possible remnant crustal and mantle material within the main asteroid belt.     

Evolutionary synthesis modelling of young star clusters in merging galaxies

The observational properties of globular cluster systems (GCSs) are vital tools to investigate the violent star formation histories of their host galaxies. This violence is thought to have been triggered by galaxy interactions or mergers. The most basic properties of a GCS are its luminosity function (number of clusters per luminosity bin) and color distributions. A large number of observed GCS show bimodal color distributions, which can be translated into a bimodality in either metallicity and/or age. An additional uncertainty comes into play when one considers extinction. These effects can be disentangled either by obtaining spectroscopic data for the clusters or by imaging observations in at least four passbands. This allows us then to discriminate between various formation scenarios of GCSs, e.g. the merger scenario by Ashman and Zepf, and the multi-phase collapse model by Forbes et al. Young and metal-rich star cluster populations are seen to form in interacting and merging galaxies. We analyse multiwavelength broad-band observations of these young cluster systems provided by the ASTROVIRTEL project. This revised version was published online in August 2006 with corrections to the Cover Date.     

The condensation origin of zoned metal grains in Queen Alexandra Range 94411: Implications for the formation of the Bencubbin‐like chondrites

Abstract— Thermodynamic analysis of the compositional profiles across large chemically‐zoned Fe, Ni metal grains in the Bencubbin‐like chondrite Queen Alexandra Range (QUE) 94411 suggests that these grains formed by non‐equilibrium gas‐solid condensation under variable oxidizing conditions, isolation degree, and Cr depletion factors. The oxidizing conditions must have resulted from the complete vaporization of nebular regions with enhanced dust/gas ratios (～ 10–40 × solar). Because the origin of each of the metal grains studied requires different condensation parameters (dust/gas ratio, isolation degree, and Cr depletion factor), a high degree of heterogeneity in the formation region of the Bencubbin‐like chondrite metal is required. To preserve compositional zoning of the metal grains and prevent their melting and sulfidization, the grains must have been removed from the hot condensation region into cold regions where the accretion of the Bencubbin‐like asteroidal body took place.     

Interferometric space missions for the search for terrestrial exoplanets: Requirements on the rejection ratio

The requirements on space missions designed to study Terrestrial exoplanets are discussed. We then investigate whether the design of such a mission, specifically the Darwin nulling interferometer, can be carried out in a simplified scenario. The key element here is accepting somewhat higher levels of stellar leakage. We establish detailed requirements resulting from the scientific rationale for the mission, and calculate detailed parameters for the stellar suppression required to achieve those requirements. We do this utilizing the Darwin input catalogue. The dominating noise source for most targets in this sample is essentially constant for all targets, while the leakage diminishes with the square of the distance. This means that the stellar leakage has an effect on the integration time only for the nearby stars, while for the more distant targets its influence decreases significantly. We assess the impact of different array configurations and nulling profiles and identify the stars for which the detection efficiency can be maximized.