Field accuracy of Canadian rain measurements

Devine, Kenneth A.; Mekis, Éva

doi:10.3137/ao.460202

Cited by 66 publications

(49 citation statements)

References 14 publications

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“…Studies on tipping bucket rain gauges have observed extensive underestimation of rainfall amounts (of up to 50%), primarily due to acceleration of airflow over the top of the gauge, with other error sources including splashing, and the finite time required for the buckets to reset in between tips during heavy rain (e.g., Devine and Mekis, 2008;Duchon and Biddle, 2010). An empirical correction was applied to the Nordic data to account for wind effects, following the work on a similar gauge by Mekonnen et al (2015).…”

Section: Rainfall Undercatchmentioning

confidence: 99%

Surface Energy Balance Closure and Turbulent Flux Parameterization on a Mid-Latitude Mountain Glacier, Purcell Mountains, Canada

2017

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In the majority of glacier surface energy balance studies, parameterization rather than direct measurement is used to estimate one or more of the individual heat fluxes, with others, such as the rain and ground heat fluxes, often deemed negligible. Turbulent fluxes of sensible and latent heat are commonly parameterized using the bulk aerodynamic technique. This method was developed for horizontal, uniform surfaces rather than sloped, inhomogeneous glacier terrain, and significant uncertainty remains regarding the selection of appropriate roughness length values, and the validity of the atmospheric stability functions employed. A customized weather station, designed to measure all relevant heat fluxes, was installed on an alpine glacier over the 2014 melt season. Eddy covariance techniques were used to observe the turbulent heat fluxes, and to calculate site-specific roughness values. The obtained dataset was used to drive a point ablation model, and to evaluate the most commonly used bulk methods and roughness length schemes in the literature. Modeled ablation showed good agreement with observed rates at seasonal, daily, and sub-daily timescales, effectively closing the surface energy balance, and giving a high level of confidence in the flux observation method. Net radiation was the dominant contributor to melt energy over the season (65.2%), followed by the sensible heat flux (29.7%), while the rain heat flux was observed to be a significant contributor on daily timescales during periods of persistent heavy rain (up to 20% day −1 ). Momentum roughness lengths observed for the study surface (snow: 10 −3.8 m; ice: 10 −2.2 m) showed general agreement with previous findings, while the scalar values (temperature: 10 −4.6 m; water vapor: 10 −6 m) differed significantly from those for momentum, disagreeing with the assumption of equal roughness lengths. Of the three bulk method stability schemes tested, the functions based on the Monin-Obukhov length returned mean daily flux values closest to those observed, but displayed poor performance on sub-daily timescales, and periods of substantial flux overestimation.

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Section: Rainfall Undercatchmentioning

confidence: 99%

Surface Energy Balance Closure and Turbulent Flux Parameterization on a Mid-Latitude Mountain Glacier, Purcell Mountains, Canada

2017

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“…Thermal conductivity of air, snowfall ). An investigation of rainfall measurements at Egbert, Ontario (Devine and Mekis, 2008), showed a catch ratio of 95 % for the Geonor-SA relative to a pit gauge, the WMO reference for rainfall intercomparison (WMO, 1969). Thus, we adjusted all rainfall measurements using the average catch efficiency of 95 % (CE = 0.95).…”

Section: Correcting For Geonor-sa Undercatchmentioning

confidence: 99%

Bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada

Xiong

Yang

et al. 2016

The Cryosphere

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Abstract. This study assesses a filtering procedure on accumulating precipitation gauge measurements and quantifies the effects of bias corrections for wind-induced undercatch across four ecoclimatic regions in western Canada, including the permafrost regions of the subarctic, the Western Cordillera, the boreal forest, and the prairies. The bias corrections increased monthly precipitation by up to 163 % at windy sites with short vegetation and sometimes modified the seasonal precipitation regime, whereas the increases were less than 13 % at sites shielded by forest. On a yearly basis, the increase of total precipitation ranged from 8 to 20 mm (3-4 %) at sites shielded by vegetation and 60 to 384 mm (about 15-34 %) at open sites. In addition, the bias corrections altered the seasonal precipitation patterns at some windy sites with high snow percentage ( > 50 %). This study highlights the need for and importance of precipitation bias corrections at both research sites and operational networks for water balance assessment and the validation of global/regional climate-hydrology models.

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“…Hourly rainfall amounts measured by the tipping bucket rainfall gauge (TBRG) observation network were used to produce the heavy rainfall indices (details on the TBRG instrument characteristics can be found in Devine and Mekis (2008) and Shephard et al (2014)). All data were retrieved from the National Climate Archive of the Meteorological Service of Canada (MSC) (Government of Canada, 2015a).…”

Section: Datamentioning

confidence: 99%

Observed Trends in Severe Weather Conditions Based on Humidex, Wind Chill, and Heavy Rainfall Events in Canada for 1953–2012

et al. 2015

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Observed trends in severe weather conditions based on public alert statements issued by Environment Canada are examined for Canada. Changes in extreme heat and extreme cold events represented by various humidex and wind chill indices are analyzed for 1953-2012 at 126 climatological stations. Changes in heavy rainfall events based on rainfall amounts provided by tipping bucket rainfall gauges are analyzed for 1960-2012 at 285 stations. The results show that extreme heat events, defined as days with at least one hourly humidex value above 30, have increased significantly at more than 36% of the stations, most of which are located south of 55°N; days with nighttime hourly humidex values remaining above 20 have increased significantly at more than 52% of the stations, most of which are located south of 50°N. Extreme cold events represented by days with at least one hourly wind chill value below −30 have decreased significantly at more than 76% of the stations across the country. No consistent changes were found in heavy rainfall events. Because city residents are very vulnerable to severe weather events, detailed results on changes in extreme heat, extreme cold, and heavy rainfall events are also provided for ten urban centres.RÉSUMÉ [Traduit par la rédaction] Nous examinons les tendances observées de conditions météorologiques extrêmes, selon les alertes destinées au public qu'émet Environnement Canada, et ce, en analysant pour la période allant de 1953 à 2012, les événements de chaleur ou de froid extrêmes, à l'aide des indices humidex et de refroidissement éolien à 126 stations climatologiques. Nous étudions l'évolution des cas de pluie abondante en comparant les accumulations de précipitations qu'ont enregistrées les pluviomètres à auget, à 285 stations, de 1960 à 2012. Les résultats montrent que les cas de chaleur extrême, définis comme étant les jours où au moins une valeur horaire de l'humidex est supérieure à 30, ont augmenté de façon significative à plus de 36% des stations, dont la plupart se situent au sud de 55°N. Le nombre de nuits où l'humidex horaire demeure supérieur à 20 a augmenté significativement à plus de 52% des stations, dont la plupart se trouvent au sud de 50°N. Les cas de froid extrême, représentés par les jours où au moins une valeur horaire du refroidissement éolien descend sous −30, ont diminué significativement à plus de 76% des stations situées partout au pays. Nous n'avons détecté aucun changement cohérent dans les cas de pluie abondante. Comme les citadins demeurent très vulnérables aux conditions météorologiques extrêmes, nous présentons des résultats détaillés sur la tendance des occurrences de chaleur et de froid extrêmes, ainsi que de pluie abondante, pour dix centres urbains.

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Field accuracy of Canadian rain measurements

Cited by 66 publications

References 14 publications

Surface Energy Balance Closure and Turbulent Flux Parameterization on a Mid-Latitude Mountain Glacier, Purcell Mountains, Canada

Surface Energy Balance Closure and Turbulent Flux Parameterization on a Mid-Latitude Mountain Glacier, Purcell Mountains, Canada

Bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada

Observed Trends in Severe Weather Conditions Based on Humidex, Wind Chill, and Heavy Rainfall Events in Canada for 1953–2012

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