Snow disappearance timing is dominated by forest effects on snow accumulation in warm winter climates of the Pacific Northwest,United States

Forests modify snow processes and affect snow water storage as well as snow disappearance timing. However, forest influences on snow accumulation and ablation vary with climate and topography and are therefore subject to temporal and spatial variability. We utilize multiple years of snow observations from across the Pacific Northwest, United States, to assess forest–snow interactions in the relatively warm winter conditions characteristic of maritime and transitional maritime–continental climates. We (a) quantify the difference in snow magnitude and disappearance timing between forests and open areas and (b) assess how forest modifications of snow accumulation and ablation combine to determine whether snow disappears later in the forest or in the open. We find that snow disappearance timing at 12 (out of 14) sites ranges from synchronous in the forest and open to snow persisting up to 13 weeks longer in the open relative to a forested area. By analyzing accumulation and ablation rates up to the day when snow first disappears from the forest, we find that the difference between accumulation rates in the open and forest is larger than the difference between ablation rates. Thus, canopy snow interception and subsequent loss, rather than ablation, set up longer snow duration in the open. However, at two relatively windy sites (hourly average wind speeds up to 8 and 17 m/s), differential snow disappearance timing is reversed: Snow persists 2–5 weeks longer in the forest. At the windiest sites, accumulation rates in the forest and open are similar. Ablation rates are higher in the open, but the difference between ablation rates in the forest and open at these sites is approximately equivalent to the difference at less windy sites. Thus, longer snow retention in the forest at the windiest sites is controlled by depositional differences rather than by reduced ablation rates. These findings suggest that improved quantification of forest effects on snow accumulation processes is needed to accurately predict the effect of forest management or natural disturbance on snow water resources.     

Virtual observatories for space and solar physics research

As soon as the first data became available online over the Internet, it was obvious that different sites holding related datasets should appear to the end user as a single data system, even if the data itself is stored at multiple locations. To achieve this objective in the context of continuing parallel development of multiple data centres, in 2003 several actors in the realm of space plasmas created the international consortium Space Physics Archive Search and Extract (SPASE). Since 2005 US participation in SPASE has been supported by NASA, and early in 2006 NASA funded five new Virtual Observatories to cater for different aspects of solar system plasma science. This paper outlines the current status of the SPASE effort, the opportunities it offers, its specificities with respect to other parts of the astronomical virtual observatory, and the possibilities it offers for space weather.

The significant role of sediment bio-retexturing within a contemporary carbonate platform system: Implications for carbonate microfacies development

Assessments of carbonate platform reef–lagoon sediments and benthic habitats around Rodrigues Island (south-west Indian Ocean) have been undertaken in order to examine carbonate sediment textural properties and the controls on texturally-defined sediment fabrics. Reef–lagoon sediments, sampled from across the expansive (~ 8 km wide) carbonate-dominated windward platform, principally comprise poorly sorted medium- to coarse-grained bioclastic sands, composed of a low diversity of grain constituents — predominantly non-geniculate coralline algal bioclasts. Despite a marked homogeneity in sediment compositional and grain size properties, eight distinct sediment textural groups can be identified that form a heterogeneous mosaic across the contemporary reef–lagoon system. Only along the narrow outer platform margins (reef crest, sand apron and outermost lagoon environments) do we observe consistent (predictable) transitions in sediment textural groups, where physical processes are the primary drivers of selective sediment transport and sorting. In contrast, across the main expanse of the lagoon, the sediment substrates are characterised by an irregular mosaic of texturally-defined sediment groups — formed primarily as a function of sediment bio-retexturing. The burrowing activities of alpheid and callianassid shrimps are particularly important in this respect and impart a distinctly unique textural fabric to the upper sediment horizons in the environments in which the respective organisms occur. The consequence of this is that, at the platform system scale, individual, texturally-defined sediment groups are relatively poor indicators of prevailing hydrodynamic regimes or of local sediment production, reflecting more the biological action of organisms inhabiting the substrate. This has important implications for understanding the development of carbonate sediment fabrics in the context of palaeoenvironmental reconstructions and for interpreting a key diagnostic criteria of carbonate microfacies.     

Correlation of Upper Cretaceous strata from Lima Peaks area to Madison Range, southwestern Montana and southeastern Idaho, USA

An⁴⁰Ar/³⁹Ar age of 85.81 Ma±0.22 my was obtained on sanidine from a volcanic procellanite bed near the top of the 2135+m-thick Upper Cretaceous Frontier Formation in the Lima Peaks area of southwestern Montana. This early Santonian age, combined with previously determined age data including a palynological age of Cenomanian for the lower Frontier at Lima Peaks, and a U-Pb isotopic date of about 95 Ma for the base of the Frontier Formation in the eastern Pioneer Mountains north of the Lima Peaks area, provides an age range for the nonmarine formation. In the Madison Range, farther east in southweastern Montana, this age range corresponds to marine strata of not only the Frontier Formation, but also the overlying Cody Shale and Telegraph Creek Formation, a sequence that totals less than 760 m thick.The Upper Cretaceous marine formations of the madison Range are closely zoned by molluscan faunas that are well constrained with radiometric dates. The⁴⁰Ar/³⁹Ar age of 85.81 Ma±0.22 my at Lima Peaks is bracketed by radiometric dates for theScaphites depressus—Protexanites bourgeoisianusbiozone and the overlyingClioscaphites saxitonianus—Inoceramus undulatopilcatusbiozone of the Western Interior. Fossils of both of these biozones are present in the Cody Shale and the Telegraph Creek Formation in the Madison Range. The Telegraph Creek contains two units of volcanic ash that are approximate time equivalents of the volcanic procellanite of the Lima Peaks area. Clasts in the conglomerate of the upper part of the Frontier in the Lima Peaks area were shed during the initial stages of uplift of the Blacktail-Snowcrest Highlands which rose to the north. The dated porcellanite lies above the conglomerates and indicates that the uplift was initiated by middle or late Coniacian, 87–88 Ma.     

Mobility and exile at 2nd century A.D. khirbet edh‐dharih: Strontium isotope analysis of human migration in western Jordan

The 2nd century A.D. Roman annexation of the Nabataean Kingdom may have resulted in significant settlement disruption. Here we investigate the possibility that political refugees occupied Khirbet edh‐Dharih after Roman takeover, using strontium isotope analysis of archaeological human dental enamel. We additionally discuss regional patterning of 87Sr/86Sr in western Jordan based on archaeological faunal dental enamel samples to understand strontium isotope spatial heterogeneity and to facilitate interpretation of the Dharih results. Strontium isotope analysis of small mammal dentition varied as expected based on bedrock geology, but small faunal sample sizes did not accurately reflect the broad range of biologically available strontium at Dharih. Only one person at Khirbet edh‐Dharh appears to be non‐local based on isotopic data. The status of the remaining individuals is unclear, as they could have originated from Dharih or the Nabataean capital city of Petra. Incorporating modern fauna and soil samples to establish the local value may assist in characterizing the local strontium in a geologically complex area such as Dharih. Futhermore, future analysis of elemental strontium to assess dietary composition and diagenetic contamination would facilitate interpretation of the strontium sources in the Dharih individuals. © 2008 Wiley Periodicals, Inc.     

A method to mitigate acid-mine drainage in the Shamokin area,Pennsylvania, U.S.A.

The three anthracite coal fields of eastern Pennsylvania occur in large synclinal basins surrounded by sandstone hogback ridges. The streams draining the coal regions are heavily contaminated by sulfuric acid due to the weathering of pyrite in the abandoned mines and culm. Dams could be built in the water gaps of the streams leaving the basins, forming huge reservoirs. For example, in the western part of the Middle Coal Field (Shamokin-Mt. Carmel area), the construction of four dams would form a reservoir that would inundate practically all the culm banks, abandoned mines, and environmentally abused lands in this coal field. The reservoir (at approximately 410 m elevation) would be approximately 140 sq km in area and could be the source of water for pumped-storage hydroelectricity generation. The water should have moderately good quality and could serve the recreational needs of a vast population of the Middle Atlantic states.