353 research outputs found
Abstract Interfaces for Data Analysis: Component Architecture for Data Analysis Tools
The fast turnover of software technologies, in particular in the domain of interactivity (covering user interface and visualisation), makes it difficult for a small group of people to produce complete and polished software-tools before the underlying technologies make them obsolete. At the HepVis '99 workshop, a working group has been formed to improve the production of software tools for data analysis in HENP. Beside promoting a distributed development organisation, one goal of the group is to systematically design a set of abstract interfaces based on using modern OO analysis and OO design techniques. An initial domain analysis has come up with several categories (components) found in typical data analysis tools: Histograms, Ntuples, Functions, Vectors, Fitter, Plotter, Analyzer and Controller. Special emphasis was put on reducing the couplings between the categories to a minimum, thus optimising re-use and maintainability of any component individually. The interfaces have been defined in Java and C++ and implementations exist in the form of libraries and tools using C++ (Anaphe/Lizard, OpenScientist) and Java (Java Analysis Studio). A special implementation aims at accessing the Java libraries (through their Abstract Interfaces) from C++. This paper gives an overview of the architecture and design of the various components for data analysis as discussed in AIDA
Recent changes in area and thickness of Torngat Mountain glaciers (northern Labrador, Canada)
The Torngat Mountains National Park, northern Labrador, Canada, contains more
than 120 small glaciers: the only remaining glaciers in continental northeast
North America. These small cirque glaciers exist in a unique topo-climatic
setting, experiencing temperate maritime summer conditions yet very cold and
dry winters, and may provide insights into the deglaciation dynamics of
similar small glaciers in temperate mountain settings. Due to their size and
remote location, very little information exists regarding the health of these
glaciers. Just a single study has been published on the contemporary
glaciology of the Torngat Mountains, focusing on net mass balances from 1981
to 1984. This paper addresses the extent to which glaciologically relevant
climate variables have changed in northern Labrador in concert with
20th-century Arctic warming, and how these changes have affected Torngat Mountain
glaciers. Field surveys and remote-sensing analyses were used to measure
regional glacier area loss of 27âŻ% from 1950 to 2005, substantial rates of
ice surface thinning (up to 6âŻmâŻyrâ1) and volume losses at Abraham,
Hidden, and Minaret glaciers, between 2005 and 2011. Glacier mass balances
appear to be controlled by variations in winter precipitation and,
increasingly, by strong summer and autumn atmospheric warming since the
early 1990s, though further observations are required to fully understand
mass balance sensitivities. This study provides the first comprehensive
contemporary assessment of Labrador glaciers and will inform both regional
impact assessments and syntheses of global glacier mass balance
Proglacial groundwater storage dynamics under climate change and glacier retreat
Proglacial aquifers are an important water store in glacierised mountain catchments that supplement meltwaterâfed river flows and support freshwater ecosystems. Climate change and glacier retreat will perturb water storage in these aquifers, yet the climateâglacierâgroundwater response cascade has rarely been studied and remains poorly understood. This study implements an integrated modelling approach that combines distributed glacioâhydrological and groundwater models with climate change projections to evaluate the evolution of groundwater storage dynamics and surfaceâgroundwater exchanges in a temperate, glacierised catchment in Iceland. Focused infiltration along the meltwaterâfed VirkisĂĄ River channel is found to be an important source of groundwater recharge and is projected to provide 14%â20% of total groundwater recharge by the 2080s. The simulations highlight a mechanism by which glacier retreat could inhibit river recharge in the future due to the loss of diurnal melt cycling in the runoff hydrograph. However, the evolution of proglacial groundwater level dynamics show considerable resilience to changes in river recharge and, instead, are driven by changes in the magnitude and seasonal timing of diffuse recharge from yearâround rainfall. The majority of scenarios simulate an overall reduction in groundwater levels with a maximum 30âday average groundwater level reduction of 1âm. The simulations replicate observational studies of baseflow to the river, where up to 15% of the 30âday average river flow comes from groundwater outside of the melt season. This is forecast to reduce to 3%â8% by the 2080s due to increased contributions from rainfall and meltwater runoff. During the melt season, groundwater will continue to contribute 1%â3% of river flow despite significant reductions in meltwater runoff inputs. Therefore it is concluded that, in the proglacial region, groundwater will continue to provide only limited buffering of river flows as the glacier retreats
Trends in Antarctic Peninsula surface melting conditions from observations and regional climate modeling
Multidecadal meteorological station records and microwave backscatter time-series from the SeaWinds scatterometer onboard QuikSCAT (QSCAT) were used to calculate temporal and spatial trends in surface melting conditions on the Antarctic Peninsula (AP). Four of six long-term station records showed strongly positive and statistically significant trends in duration of melting conditions, including a 95% increase in the average annual positive degree day sum (PDD) at Faraday/Vernadsky, since 1948. A validated, threshold-based melt detection method was employed to derive detailed melt season onset, extent, and duration climatologies on the AP from enhanced resolution QSCAT data during 1999â2009. Austral summer melt on the AP was linked to regional- and synoptic-scale atmospheric variability by respectively correlating melt season onset and extent with November near-surface air temperatures and the OctoberâJanuary averaged index of the Southern Hemisphere Annular Mode (SAM). The spatial pattern, magnitude, and interannual variability of AP melt from observations was closely reproduced by simulations of the regional model RACMO2. Local discrepancies between observations and model simulations were likely a result of the QSCAT response to, and RACMO2 treatment of, ponded surface water, and the relatively crude representation of coastal climate in the 27âkm RACMO2 grid
Future evolution and uncertainty of river flow regime change in a deglaciating river basin
The flow regimes of glacier-fed rivers are sensitive to climate change due to
strong climateâcryosphereâhydrosphere interactions. Previous modelling
studies have projected changes in annual and seasonal flow magnitude but
neglect other changes in river flow regime that also have socio-economic and
environmental impacts. This study employs a signature-based analysis of
climate change impacts on the river flow regime for the deglaciating VirkisĂĄ
river basin in southern Iceland. Twenty-five metrics (signatures) are derived from 21st century projections of river flow time series to evaluate changes in
different characteristics (magnitude, timing and variability) of river flow
regime over sub-daily to decadal timescales. The projections are produced by
a model chain that links numerical models of climate and glacio-hydrology.
Five components of the model chain are perturbed to represent their
uncertainty including the emission scenario, numerical climate model,
downscaling procedure, snow/ice melt model and runoff-routing model. The
results show that the magnitude, timing and variability of glacier-fed river
flows over a range of timescales will change in response to climate change.
For most signatures there is high confidence in the direction of change, but
the magnitude is uncertain. A decomposition of the projection uncertainties
using analysis of variance (ANOVA) shows that all five perturbed model chain
components contribute to projection uncertainty, but their relative
contributions vary across the signatures of river flow. For example, the
numerical climate model is the dominant source of uncertainty for projections
of high-magnitude, quick-release flows, while the runoff-routing model is
most important for signatures related to low-magnitude, slow-release flows.
The emission scenario dominates mean monthly flow projection uncertainty, but
during the transition from the cold to melt season (April and May) the
snow/ice melt model contributes up to 23 % of projection uncertainty.
Signature-based decompositions of projection uncertainty can be used to
better design impact studies to provide more robust projections.</p
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Technology Enhanced Learning in UK higher education - 2022 pulse survey
This 2022 Technology Enhanced Learning (TEL) Survey was developed as a short âpulse surveyâ to focus on key areas that might have been impacted by the COVID-19 pandemic and the rapid shift to online learning. The survey retained and adapted 16 questions from the 2020 Survey to enable longitudinal analysis to be undertaken with previous TEL surveys. The Survey provides an invaluable insight of provision within institutions and the emerging patterns of learning technology usage across the UK HE sector. The 2022 findings report an increased provision of centrally supported TEL tools, an increase in outsourcing of TEL provision and an increase in TEL staffing. The findings also show that the sector is undergoing a continuous review cycle for TEL services, note a small growth in fully online delivery and the limited impact of new forms of delivery such as hybrid or HyFlex learning
GAUDI: The software architecture and framework for building LHCb data processing applications
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