Geography and Environment

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Browsing Geography and Environment by Author "Barnes, Celeste"

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    Montane seasonal and elevational precipitation gradients in the southern Rockies of Alberta, Canada
    (Wiley, 2025) Barnes, Celeste; MacDonald, Ryan J.; Hopkinson, Chris
    Modelling precipitation inputs in mountainous terrain is challenging for water resource managers given sparse monitoring sites and complex physical hydroclimatic processes. Government of Alberta weather station uncorrected and bias-corrected precipitation datasets were used to examine elevational precipitation gradients (EPGs) and seasonality of EPGs for six South-Saskatchewan River headwater sites (alpine, sub-alpine, valley). January EPG from valley to alpine sites (730 m elevation difference) using uncorrected precipitation was 19 mm/100 m. Corrected EPG was approximately three times greater (61 mm/100 m). The valley received more precipitation than the alpine (inverse EPG) in late spring and summer. A seasonal signal was present whereby all sites demonstrated 50%–70% lower summertime precipitation relative to winter months, with the greatest seasonal variance at the alpine site. Winter watershed-level spatialized precipitation volume was compared to modelled snow water equivalent (SWE) associated with two late-winter airborne lidar surveys. Uncorrected volumes (2020: 64.0 × 106m3, 2021: 63.2 × 106m3) were slightly higher than modelled mean SWE (2020: 51.6 × 106m3, 2021: 44.2 × 106m3) whereas bias-corrected (2020: 120.5 × 106m3, 2021: 119.7 × 106m3) almost doubled the estimate. Corrected precipitation is assumed closer to the true value. Cumulative sublimation, evaporation and snowmelt losses result in ground-level snowpack yield that deviates from total atmospheric precipitation in an increasingly negative manner. The 2020/2021 simulations suggest wintertime atmospheric precipitation exceeds late-winter snowpack accumulation by up to 57% and 63%, respectively. A loss of 16 × 106m3 (7%) watershed SWE from the alpine zone was partially attributed to redistribution downslope to the treeline-ecotone. Physical snowpack losses from sublimation and melt, or modelling uncertainty due to precipitation correction and alpine snow-density uncertainties can also contribute to observed discrepancies between in situ SWE and cumulative precipitation. Ignoring bias-correction in headwater precipitation estimates can greatly impact headwater precipitation volume estimates and ignoring EPG seasonality is likely to result in under-estimated winter and over-estimated summer yields.
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    Quality control impacts on total precipitation gauge records for montane valley and ridge sites in SW Alberta, Canada
    (MDPI, 2022) Barnes, Celeste; Hopkinson, Christopher
    This paper presents adjustment routines for Geonor totalizing precipitation gauge data collected from the headwaters of the Oldman River, within the southwestern Alberta Canadian Rockies. The gauges are situated at mountain valley and alpine ridge locations with varying degrees of canopy cover. These data are prone to sensor noise and environment-induced measurement errors requiring an ordered set of quality control (QC) corrections using nearby weather station data. Sensor noise at valley sites with single-vibrating wire gauges accounted for the removal of 5% to 8% (49–76 mm) of annual precipitation. This was compensated for by an increase of 6% to 8% (50–76 mm) from under-catch. A three-wire ridge gauge did not experience significant sensor noise; however, the under-catch of snow resulted in 42% to 52% (784–1342 mm) increased precipitation. When all QC corrections were applied, the annual cumulative precipitation at the ridge demonstrated increases of 39% to 49% (731–1269 mm), while the valley gauge adjustments were −4% to 1% (−39 mm to 13 mm). Public sector totalizing precipitation gauge records often undergo minimal QC. Care must be exercised to check the corrections applied to such records when used to estimate watershed water balance or precipitation orographic enhancement. Systematic errors at open high-elevation sites may exceed nearby valley or forest sites.