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Varhola A.,University of British Columbia | Wawerla J.,Simon Fraser University | Weiler M.,Albert Ludwigs University of Freiburg | Coops N.C.,University of British Columbia | And 2 more authors.
Journal of Atmospheric and Oceanic Technology | Year: 2010

Monitoring continuous changes in snowpack dynamics and its meteorological drivers is critical for understanding key aspects of water resources, climate variability, and ecology. While manual snow surveys have traditionally been used to evaluate snow processes, their high costs and discrete measurements can lead to biased estimations of accumulation and ablation rates. Ultrasonic range sensors offer an alternative to continuously monitor snow depth but their widespread employment has been limited because of high prices. This paper describes the development of an inexpensive prototype ultrasonic sensor suite characterized by a ready-to-use stand-alone design and flexibility to incorporate additional meteorological instruments. The performance of 48 units was tested during a winter season in central British Columbia, recording snow depth and air temperature data consistent with those from nearby weather stations and manual measurements. Despite a relatively small underestimation of snow depth due to known, repairable reasons, the sensor system demonstrated reliability for research and operations. © 2010 American Meteorological Society. Source

Guenther S.M.,Hatfield Consultants | Moore R.D.,University of British Columbia | Gomi T.,Tokyo University of Agriculture and Technology
Agricultural and Forest Meteorology | Year: 2012

This study focused on a headwater forest stream in coastal British Columbia, Canada. Air temperature, humidity and wind speed were measured at a height of 1.5. m above the stream and at a control site within a clearcut located approximately 1. km from the study stream, both before and after partial-retention forest harvesting along the stream. A specially designed evaporimeter was used to measure evaporation. Laboratory trials confirmed the reliability of evaporimeter measurements. Prior to harvesting, wind speeds were low and vapour pressure gradients above the stream were weak, leading to low rates of evaporation. Following harvesting, the decreased shading and increased ventilation over the stream led to higher wind speeds, lower vapour pressures, higher daily maximum air temperatures, higher stream temperatures and surface vapour pressures, and higher rates of evaporation. A wind function that has been used to estimate stream evaporation in a number of previous studies, but which had not been compared to measured stream evaporation, was found to overestimate evaporation. An empirical wind function fitted to the evaporimeter data differed from three others that have been derived for predicting stream evaporation in that our data did not support the inclusion of an intercept. It is hypothesized that the lack of an intercept for our data reflects the strongly stable conditions over the stream. Further research should measure stream evaporation over a broad range of streamflow and meteorological conditions, with particular attention to the role of atmospheric stability. © 2012 Elsevier B.V. Source

Guenther S.M.,Hatfield Consultants | Gomi T.,Tokyo University of Agriculture and Technology | Moore R.D.,University of British Columbia
Hydrological Processes | Year: 2014

Stream temperature was recorded between 2002 and 2005 at four sites in a coastal headwater catchment in British Columbia, Canada. Shallow groundwater temperatures, along with bed temperature profiles at depths of 1 to 30cm, were recorded at 10-min intervals in two hydrologically distinct reaches beginning in 2003 or 2004, depending on the site. The lower reach had smaller discharge contributions via lateral inflow from the hillslopes and fewer areas with upwelling (UW) and/or neutral flow across the stream bed compared to the middle reach. Bed temperatures were greater than those of shallow groundwater during summer, with higher temperatures in areas of downwelling (DW) flow compared to areas of neutral and UW flow. A paired-catchment analysis revealed that partial-retention forest harvesting in autumn 2004 resulted in higher daily maximum stream and bed temperatures but smaller changes in daily minima. Changes in daily maximum stream temperature, averaged over July and August of the post-harvest year, ranged from 1.6 to 3°C at different locations within the cut block. Post-harvest changes in bed temperature in the lower reach were smaller than the changes in stream temperature, greater at sites with DW flow, and decreased with depth at both UW and DW sites, dropping to about 1°C at a depth of 30cm. In the middle reach, changes in daily maximum bed temperature, averaged over July and August, were generally about 1°C and did not vary significantly with depth. The pre-harvest regression models for shallow groundwater were not suitable for applying the paired-catchment analysis to estimate the effects of harvesting. However, shallow groundwater was warmer at the lower reach following harvesting, despite generally cooler weather compared to the pre-harvest year. © 2012 John Wiley & Sons, Ltd. Source

McDonald B.G.,Golder Associates | deBruyn A.M.,Golder Associates | Elphick J.R.,Nautilus Environmental | Davies M.,Hatfield Consultants | And 2 more authors.
Environmental Toxicology and Chemistry | Year: 2010

Gametes were collected from Dolly Varden char (Salvelinus malma) from waterbodies in a region exposed to mining-related selenium (Se) releases in British Columbia, Canada. Fertilized eggs were incubated in a laboratory and deformities were assessed on newly-hatched alevins using a graduated severity index. No effects were observed on egg or alevin survival or larval weight across the studied exposure range of 5.4 to 66 mg/kg dry weight in egg. Length of some larvae was reduced at the highest egg Se concentrations and a clear residue-response relationship was observed for larval deformity. The egg concentration corresponding to a 10% increase in the frequency of deformity (EC10) was 54 mg/kg dry weight, which is substantially higher than reported for other cold-water fish species. © 2010 SETAC. Source

Wang Y.-C.,National University of Singapore | Srivathsan A.,National University of Singapore | Feng C.-C.,National University of Singapore | Salim A.,Hatfield Consultants | Shekelle M.,Portland State University
PLoS ONE | Year: 2013

Previous studies of meta-analyses found significantly positive correlations between primate species richness and rainfall for Africa, Madagascar and the Neotropics, with the exception of Asia, leaving the open question whether that anomaly is the result of sampling bias, biogeography, or some other factor. This study re-examines the question using modelled data, with primate species richness data from the Southeast Asian Mammals Databank and rainfall data from the Climatic Research Unit. Data processing with Geographical Information Systems resulted in 390 sample points. Reduced major axis and ordinary least squares regressions were employed to examine the relationship for six regions, including the whole study area of Southeast Asia, and the subareas of Huxley West, Huxley East, Mainland Southeast Asia, Borneo, and Sumatra. The results showed a significant positive relationship between primate species richness and mean annual rainfall for Southeast Asia (r = 0.26, P<0.001). Comparing the results for the large islands and Mainland Southeast Asia showed that Sumatra had the highest correlation (r = 0.58; P<0.05). After controlling for the major biogeographic effect associated with Huxley's Line, our results showed that primate species richness is positively associated with mean annual rainfall in Southeast Asia. Our findings contrast to prior studies of meta-analyses that showed no relationship between rainfall and primate species richness in Asia, and thereby bring Asia into agreement with results showing significant positive correlations between rainfall and primate species richness everywhere else in the world. The inference is that previous anomalous results for Asia were result of sampling bias in the meta-analysis. © 2013 Wang et al. Source

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