Dynamical properties of the spatial distribution of snow

International audienceA simulation exercise has been performed to study the temporal development of snow covered area and the spatial distribution of snow-water equivalent (SWE). Special consideration has been paid to how the properties of the spatial statistical distribution of SWE change as a response to accumulation and ablation events. A distributed rainfall-runoff model at resolution 1 x 1 km2 has been run with time series of precipitation and temperature fields of the same spatial resolution derived from the atmospheric model HIRLAM. The precipitation fields are disaggregated and the temperature fields are interpolated. Time series of the spatial distribution of snow-water equivalent and snow-covered area for three seasons for a catchment in Norway is generated. The catchment is of size 3085 km2 and two rectangular sub-areas of 484 km2 are located within the larger catchment. The results show that the shape of the spatial distribution of SWE for all three areas changes during winter. The distribution is very skewed at the start of the accumulation season but then the skew decreases and, as the ablation season sets in, the spatial distribution again becomes more skewed with a maximum near the end of the ablation season. For one of the sub-areas, a consistently more skewed distribution of SWE is found, related to higher variability in precipitation. This indicates that observed differences in the spatial distribution of snow between alpine and forested areas can result from differences in the spatial variability of precipitation. The results obtained from the simulation exercise are consistent with modelling the spatial distribution of SWE as summations of a gamma distributed variable. Keywords: Snow, SWE, spatial distribution, simulated hydrometeorological field

THE USE OF COHESIVE DEVICES IN ENGLISH EDUCATION STUDENTS’ WRITINGS

This study discovers how cohesive devices used in twelve students’ writing written by four students – two high achiever learners and two low achiever learners – of English Education Program in Indonesian University. With the characteristics of case study approach, the research study applies a qualitative method research design and employs Halliday and Hasan’s (1976) taxonomy of cohesion framework as a ground theory and a tool for text analysis. The findings show that grammatical cohesive devices are used slightly more frequent than the lexical ones. The students frequently used reiteration followed by reference, conjunction, collocation, substitution, and ellipsis with two general functions; to remind the readers about the topic discussed and to show the position of the author within the text. Furthermore, it is realized that to some extent, the way students use cohesive devices is a little bit different; in which at the final point, high achiever learners tend to use more various cohesive devices than the low ones in maintaining their quality of writing. Keywords: Cohesion, Cohesive Devices, Writing Quality Penggunaan Perangkat Kohesif di Tulisan-tulisan Mahasiswa Pendidikan Bahasa Inggris Penelitian ini mengemukakan bagaimana perangkat kohesif digunakan pada dua belas tulisan buatan empat mahasiswa – dua siswa berprestasi tinggi dan dua siswa berprestasi rendah – jurusan pendidikan bahasa inggris di salah satu universitas di Indonesia. Dengan karakteristik pendekatan studi kasus, penelitian ini menerapkan metode kualitatif dan menggunakan taksonomi kerangka kohesi yang diusung Halliday dan Hasan (1976) sebagai teori dasar dan alat untuk menganalisis teks. Temuan menunjukan bahwa perangkat kohesif gramatikal digunakan sedikit lebih sering daripada yang leksikal. Para siswa seringkali menggunakan reiteration diikuti oleh reference, conjunction, collocation, substitution, dan ellipsis dengan dua fungsi umum; untuk mengingatkan pembaca tentang topic yang sedang dibahas dan untuk menunjukan posisi penulis didalam teks. Selanjutnya, disadari bahwa pada titik-titik tertentu, cara siswa menggunakan perangkat kohesif sedikit berbeda; yang mana pada akhirnya, siswa yang berprestasi tinggi cenderung menggunakan perangkat kohesif yang lebih variatif daripada yang digunakan oleh siswa yang berprestasi rendah dalam mempertahankan kualitas tulisannya. Kata Kunci: Kohesi, Perangkat Kohesif, Kualitas Tulisa

Elvetilførsler og direkte tilførsler til norske kystområder – 2016

Project manager Øyvind KasteRiverine inputs and direct discharges to Norwegian coastal waters in 2016 have been estimated in accordance with the OSPAR Commission’s principles. Nutrients, metals and organic pollutants have been monitored in rivers; discharges from point sources have been estimated from industry, sewage treatment plants and fish farming; and nutrient inputs from diffuse sources have been modelled. Trends in riverine inputs have been analysed, and threshold concentration levels investigated.Norwegian Environment AgencypublishedVersio

Influence of spatial resolution on snow cover dynamics for a coastal and mountainous region at high latitudes (Norway)

Climate models show that global warming will disproportionately influence high‐latitude regions and indicate drastic changes in, among others, seasonal snow cover. However, current continental and global simulations covering these regions are often run at coarse grid resolutions, potentially introducing large errors in computed fluxes and states. To quantify some of these errors, we have assessed the sensitivity of an energy‐balance snow model to changes in grid resolution using a multiparametrization framework for the spatial domain of mainland Norway. The framework has allowed us to systematically test how different parametrizations, describing a set of processes, influence the discrepancy, here termed the scale error, between the coarser (5 to 50‐km) and finest (1‐km) resolution. The simulations were set up such that liquid and solid precipitation was identical between the different resolutions, and differences between the simulations arise mainly during the ablation period. The analysis presented in this study focuses on evaluating the scale error for several variables relevant for hydrological and land surface modelling, such as snow water equivalent and turbulent heat exchanges. The analysis reveals that the choice of method for routing liquid water through the snowpack influences the scale error most for snow water equivalent, followed by the type of parametrizations used for computing turbulent heat fluxes and albedo. For turbulent heat exchanges, the scale error is mainly influenced by model assumptions related to atmospheric stability. Finally, regions with strong meteorological and topographic variability show larger scale errors than more homogenous regions.publishedVersio

Upscaling of methane exchange in a boreal forest using soil chamber measurements and high-resolution LiDAR elevation data

Forest soils are generally considered to be net sinks of methane (CH4), but CH4 fluxes vary spatially depending on soil conditions. Measuring CH4 exchange with chambers, which are commonly used for this purpose, might not result in representative fluxes at site scale. Appropriate methods for upscaling CH4 fluxes from point measurements to site scale are therefore needed. At the boreal forest research site, Norunda, chamber measurements of soils and vegetation indicate that the site is a net sink of CH4, while tower gradient measurements indicate that the site is a net source of CH4. We investigated the discrepancy between chamber and tower gradient measurements by upscaling soil CH4 exchange to a 100 ha area based on an empirical model derived from chamber measurements of CH4 exchange and measurements of soil moisture, soil temperature and water table depth. A digital elevation model (DEM) derived from high-resolution airborne Light Detection and Ranging (LiDAR) data was used to generate gridded water table depth and soil moisture data of the study area as input data for the upscaling. Despite the simplistic approach, modeled fluxes were significantly correlated to four out of five chambers with R>0.68. The upscaling resulted in a net soil sink of CH4 of -10 mu mol m(-2) h(-1), averaged over the entire study area and time period June-September, 2010). Our findings suggest that additional contributions from CH4 soil sources outside the upscaling study area and possibly CH4 emissions from vegetation could explain the net emissions measured by tower gradient measurements. (C) 2015 Elsevier B.V. All rights reserved

Quantifying the Ocean, Freshwater and Human Effects on Year-to-Year Variability of One-Sea-Winter Atlantic Salmon Angled in Multiple Norwegian Rivers

Many Atlantic salmon, Salmo salar, populations are decreasing throughout the species' distributional range probably due to several factors acting in concert. A number of studies have documented the influence of freshwater and ocean conditions, climate variability and human impacts resulting from impoundment and aquaculture. However, most previous research has focused on analyzing single or only a few populations, and quantified isolated effects rather than handling multiple factors in conjunction. By using a multi-river mixed-effects model we estimated the effects of oceanic and river conditions, as well as human impacts, on year-to-year and between-river variability across 60 time series of recreational catch of one-sea-winter salmon (grilse) from Norwegian rivers over 29 years (1979–2007). Warm coastal temperatures at the time of smolt entrance into the sea and increased water discharge during upstream migration of mature fish were associated with higher rod catches of grilse. When hydropower stations were present in the course of the river systems the strength of the relationship with runoff was reduced. Catches of grilse in the river increased significantly following the reduction of the harvesting of this life-stage at sea. However, an average decreasing temporal trend was still detected and appeared to be stronger in the presence of salmon farms on the migration route of smolts in coastal/fjord areas. These results suggest that both ocean and freshwater conditions in conjunction with various human impacts contribute to shape interannual fluctuations and between-river variability of wild Atlantic salmon in Norwegian rivers. Current global change altering coastal temperature and water flow patterns might have implications for future grilse catches, moreover, positioning of aquaculture facilities as well as the implementation of hydropower schemes or other encroachments should be made with care when implementing management actions and searching for solutions to conserve this species

Understanding of Coupled Terrestrial Carbon, Nitrogen and Water Dynamics—An Overview

Coupled terrestrial carbon (C), nitrogen (N) and hydrological processes play a crucial role in the climate system, providing both positive and negative feedbacks to climate change. In this review we summarize published research results to gain an increased understanding of the dynamics between vegetation and atmosphere processes. A variety of methods, including monitoring (e.g., eddy covariance flux tower, remote sensing, etc.) and modeling (i.e., ecosystem, hydrology and atmospheric inversion modeling) the terrestrial carbon and water budgeting, are evaluated and compared. We highlight two major research areas where additional research could be focused: (i) Conceptually, the hydrological and biogeochemical processes are closely linked, however, the coupling processes between terrestrial C, N and hydrological processes are far from well understood; and (ii) there are significant uncertainties in estimates of the components of the C balance, especially at landscape and regional scales. To address these two questions, a synthetic research framework is needed which includes both bottom-up and top-down approaches integrating scalable (footprint and ecosystem) models and a spatially nested hierarchy of observations which include multispectral remote sensing, inventories, existing regional clusters of eddy-covariance flux towers and CO2 mixing ratio towers and chambers