John W. Pomeroy

Bio: John W. Pomeroy is an academic researcher from University of Saskatchewan. The author has contributed to research in topics: Snow & Snowmelt. The author has an hindex of 67, co-authored 314 publications receiving 15646 citations. Previous affiliations of John W. Pomeroy include National Water Research Institute & University of Idaho.

IAHS Decade on Predictions in Ungauged Basins (PUB), 2003–2012: Shaping an exciting future for the hydrological sciences

Abstract: Drainage basins in many parts of the world are ungauged or poorly gauged, and in some cases existing measurement networks are declining. The problem is compounded by the impacts of human-induced changes to the land surface and climate, occur-ring at the local, regional and global scales. Predictions of ungauged or poorly gauged basins under these conditions are highly uncertain. The IAHS Decade on Predictions in Ungauged Basins, or PUB, is a new initiative launched by the International Association of Hydrological Sciences (IAHS), aimed at formulating and implementing appropriate science programmes to engage and energize the scientific community, in a coordinated manner, towards achieving major advances in the capacity to make predictions in ungauged basins. The PUB scientific programme focuses on the estimation of predictive uncertainty, and its subsequent reduction, as its central theme. A general hydrological prediction system contains three components: (a) a model that describes the key processes of interest, (b) a set of parameters that represent those landscape properties that govern critical processes, and (c) appropriate meteorological inputs (where needed) that drive the basin response. Each of these three components of the prediction system, is either not known at all, or at best known imperfectly, due to the inherent multi-scale space-time heterogeneity of the hydrological system, especially in ungauged basins. PUB will therefore include a set of targeted scientific programmes that attempt to make inferences about climatic inputs, parameters and model structures from available but inadequate data and process knowledge, at the basin of interest and/or from other similar basins, with robust measures of the uncertainties involved, and their impacts on predictive uncertainty. Through generation of improved understanding, and methods for the efficient quantification of the underlying multi-scale heterogeneity of the basin and its response, PUB will inexorably lead to new, innovative methods for hydrological predictions in ungauged basins in different parts of the world, combined with significant reductions of predictive uncertainty. In this way, PUB will demonstrate the value of data, as well as provide the information needed to make predictions in ungauged basins, and assist in capacity building in the use of new technologies. This paper presents a summary of the science and implementation plan of PUB, with a call to the hydrological community to participate actively in the realization of these goals.

A decade of Predictions in Ungauged Basins (PUB)—a review

Abstract: The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS), launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23–25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power. This paper reviews the work that has been done under the six science themes of the PUB Decade and outlines the challenges ahead for the hydrological sciences community.Editor D. KoutsoyiannisCitation Hrachowitz, M., Savenije, H.H.G., Bloschl, G., McDonnell, J.J., Sivapalan, M., Pomeroy, J.W., Arheimer, B., Blume, T., Clark, M.P., Ehret, U., Fenicia, F., Freer, J.E., Gelfan, A., Gupta, H.V., Hughes, D.A., Hut, R.W., Montanari, A., Pande, S., Tetzlaff, D., Troch, P.A., Uhlenbrook, S., Wagener, T., Winsemius, H.C., Woods, R.A., Zehe, E., and Cudennec, C., 2013. A d...

Measurements and modelling of snow interception in the boreal forest

Abstract: Snow accumulation and ablation processes are particularly important to the hydrology of cold climate forests. In order to calculate the distribution of snow cover and the loss of snow to sublimation, the amount of snowfall intercepted by forest canopies must be determined. This paper introduces a physically-based snowfall interception model that scales snowfall interception processes from branch to canopy. Previous models of snow interception have neglected the persistent presence and subsequent unloading of intercepted snow in cold climates and hence have only been applicable to regions where snow is quickly lost from the canopy. To investigate how snow is intercepted at the forest stand scale, measurements of wind speed, air temperature, above- and below-canopy snowfall, accumulation of snow on the ground and the load of snow intercepted by a suspended, weighed, full-size conifer were collected from spruce and pine stands in the southern boreal forest. These data show that interception increases at a declining rate with increasing snowfall, to a point where the intercepted load overcomes the strength of branches to support it. Leaf area, tree species and initial canopy snow load determine the snow storage capacity of the canopy. These factors, canopy coverage and snowfall are used to calculate snow interception, presuming an exponential decay in incremental interception as cumulative snowfall increases. The subsequent unloading of intercepted snow is additionally modelled as an exponential function of time. The sensitivity of the combined model to temperature, wind speed, snowfall, snow load and canopy structure is examined for weekly time-steps. The examination shows that interception efficiency is particularly sensitive to snowfall amount, canopy density and time since snowfall. A comparison of the model with weekly measurements of snow interception suggests that the method can be used to calculate snow interception successfully in a physically-based manner.

The cold regions hydrological model: a platform for basing process representation and model structure on physical evidence

Abstract: After a programme of integrated field and modelling research, hydrological processes of considerable uncertainty such as snow redistribution by wind, snow interception, sublimation, snowmelt, infiltration into frozen soils, hillslope water movement over permafrost, actual evaporation, and radiation exchange to complex surfaces have been described using physically based algorithms. The cold regions hydrological model (CRHM) platform, a flexible object-oriented modelling system was devised to incorporate these algorithms and others and to connect them for purposes of simulating the cold regions hydrological cycle over small to medium sized basins. Landscape elements in CRHM can be linked episodically in process-specific cascades via blowing snow transport, overland flow, organic layer subsurface flow, mineral interflow, groundwater flow, and streamflow. CRHM has a simple user interface but no provision for calibration; parameters and model structure are selected based on the understanding of the hydrological system; as such the model can be used both for prediction and for diagnosis of the adequacy of hydrological understanding. The model is described and demonstrated in basins from the semi-arid prairie to boreal forest, mountain and muskeg regions of Canada where traditional hydrological models have great difficulty in describing hydrological phenomena. Some success is shown in simulating various elements of the hydrological cycle without calibration; this is encouraging for predicting hydrology in ungauged basins.

Climate Change 2007: The Physical Science Basis.

Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

Principles of Terrestrial Ecosystem Ecology

Abstract: I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

Remote Sensing And Image Interpretation

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