Twenty-Seven Years of Manual Fresh Snowfall Density Measurements on Whistler Mountain, British Columbia

Abstract

Snow density is important information for a wide range of activities including avalanche control, marketing, building-code development, weather forecasting, and water supply forecasting. Extended recent high-quality datasets from the mountainous regions of the Pacific Northwest coastal area are rare. This paper presents a study of an unusually long and continuous (January 1990 to April 2016) manually collected dataset of fresh snowfall measurements for Whistler Mountain, British Columbia, Canada. The dataset consists of snowboard core measurements that were collected by Whistler-Blackcomb ski patrol staff twice daily for avalanche control and resort-marketing purposes. These records were collated, transcribed, quality controlled, and made computer accessible in this study. A discussion of the characteristics of the data collection site and an assessment of data reliability are presented. Two examples of the many purposes to which this high-quality dataset might be put were studied. Climatic teleconnections to winter (December-February) mean snow density were examined, which revealed a positive relationship to the quadratic form of the Pacific Decadal Oscillation pattern (i.e., PDO 2 ). In addition, an analysis of daily snow density relationships to air mass types was performed, which suggested that higher (lower) densities are associated with maritime inflow (arctic outflow) conditions. Both of these relationships appear to be mediated by the positive correlation between snow density and air temperature.Based on the full dataset (N = 1275 individual snow density measurements) for all months with measured snowfall, annual snowfall season (November to May) mean snow densities ranged from 77 kg m −3 to 109 kg m −3 with an overall mean of 91 kg m −3 , giving an overall snow-depth to water-depth ratio of 11:1.RÉSUMÉ [Traduit par la rédaction] La densité de la neige s'avère une information importante pour une large gamme d'activités, y compris la prévention des avalanches, la publicité, la rédaction de codes du bâtiment, la pré-vision météorologique et la prévision d'approvisionnement en eau. Les longues séries de données récentes et de haute qualité restent rares pour les montagnes de la côte nord-ouest de la région pacifique. Nous présentons l'étude d'une série de mesures de neige fraîche inhabituellement longue et continue (janvier 1990 à avril 2016), qui a été relevée manuellement au mont Whistler en Colombie-Britannique, Canada. Deux fois par jour, pour des raisons de prévention des avalanches et de publicité, la patrouille de ski de Whistler-Blackcomb a recueilli des carottes de neige à partir d'une table à neige. Ces relevés ont été colligés, transcrits, vérifiés et informatisés pour cette étude. Nous présentons aussi les caractéristiques du site de mesure et une évaluation de la fiabilité des données. De plus, nous avons étudié deux exemples des nombreuses utilités de cette série de données de haute qualité. Nous avons examiné les téléconnexions climatologiques avec la densité moyenne de la neige en ...

Characterizing Maritime Snow Canopy Interception in Forested Mountains

“…Although the use of daily mean air temperature as a proxy for snowfall temperature may introduce biases, measured values across our study are in line with a recent study of fresh snowfall density within a similar climate. A long‐term record of new snowfall from a maritime snow environment in Whistler‐Blackcomb, British Columbia, Canada, measured by the resort ski‐patrol from 1990 to 2016 indicates that mean new snowfall had ρ snow = 91 kg/m 3 , with a median of 85 kg/m 3 and a range of snowfall density values from 77‐109 kg/m 3 (Barton, ).…”

Author Response to RC1

“…I would suggest to extend the discussion section and compare the results with some relevant previous studies (e.g. McClung, 2013, Barton 2017 to indicate more clearly how do the new results fit to previous studies and how the interpolated (cloud reduced) MODIS datasets can improve (are improving) the prediction of the impact of ONI and PDO. Are the mean absolute errors of prediction comparable/small/large compared to results of previous investigations [.…”

“…In addition, the LOWESS allows us to detect the start and end dates of snow, which is an important contribution to our understanding of snow cover in British Columbia. We suggest that to extend this work further into the past, one could use lower resolution remote sensing data, or in-situ observations, and we include the provided references of (McClung, 2013, Barton 2017. These methods could likely be implemented in other regions, however the dates of the hydrological year will likely be different, and so could the optimal NDSI threshold.…”

“…This allowed us to not only detect SDDUR from the time series, but also SDON and SDOFF. To extend this work further back in time, one could use lower spatial resolution AVHRR data (Allchin and Déry, 2017), or investigate in situ measurements (McClung, 2013;Barton, 2017). Our methods could be used anywhere that the MODIS snow cover product is present, however the definition of the hydrological year, the LOWESS bandwidth, and the NDSI thresholds may need to be optimized.…”

Author Response to RC2

“…This allowed us to not only detect SDDUR from the time series, but also SDON and SDOFF. To extend this work further back in time, one could use lower spatial resolution AVHRR data (Allchin and Déry, 2017), or investigate in situ measurements (McClung, 2013;Barton, 2017). Our methods could be used anywhere that the MODIS snow cover product is present, however the definition of the hydrological year, the LOWESS bandwidth, and the NDSI thresholds may need to be optimized.…”