Rainfall Measurement in Canada: Changing Observational Methodsand Archive Adjustment Procedures

Metcalfe, John R.; Routledge, Bruce; Devine, Kenneth A.

doi:10.1175/1520-0442(1997)010<0092:rmicco>2.0.co;2

Cited by 74 publications

(60 citation statements)

References 5 publications

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“…It uses two different precipitation gauges simultaneously, one to measure solid precipitation and the other to measure liquid precipitation. As of the early to mid-1970s, the Type B nonrecording rain gauge has been used to measure liquid precipitation at more than 2500 Environment Canada stations [Metcalfe et al, 1996]. Currently, the shielded Canadian Nipher gauge is used to measure fresh snowfall water equivalent (as well as liquid precipitation) at 561 stations (Environment Canada, http://www.canada.gc.ca, 2002).…”

Section: Determination Of Crs For Canadamentioning

confidence: 99%

“…Currently, the shielded Canadian Nipher gauge is used to measure fresh snowfall water equivalent (as well as liquid precipitation) at 561 stations (Environment Canada, http://www.canada.gc.ca, 2002). At about 1800 stations, a snow ruler is used to measure snow depth which is then converted to water equivalent by assuming that the density of fresh snow is 100 kg/m 3 [Metcalfe et al, 1996].…”

Section: Determination Of Crs For Canadamentioning

confidence: 99%

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Adjustment of global gridded precipitation for systematic bias

2003

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[1] Systematic biases in gauge-based measurement of precipitation can be substantial. Of the sources of bias, wind-induced undercatch of solid precipitation is by far the largest. A methodology for producing gridded mean monthly catch ratios (CRs) for the adjustment of wind-induced undercatch and wetting losses is developed, which is suitable for application to continental or global gridded precipitation products. The adjustments for wind-induced solid precipitation were estimated using gauge type-specific regression equations from the recent World Meteorological Organization Solid Precipitation Measurement Intercomparison. Wind-induced undercatch of liquid precipitation and wetting losses were estimated using methods employed in previous global bias adjustment efforts. Due to the unique nature of Canada's precipitation measurement network, the Canadian adjustments were determined using more detailed information than for the rest of the domain, and are therefore expected to be more reliable. The gridded gauge adjustment products are designed to be applicable both to climatological estimates and to individual years during the 1979 through 1998 reference period. Application of the CRs to an existing precipitation product yielded an increase in mean annual global terrestrial precipitation of 11.7%. As compared with recent (but more localized) studies that used a similar method to account for wind-induced catch deficiencies, our estimates of wind-induced undercatch are 1.6-7.9% higher on a mean annual basis. Compared to a previous global precipitation bias adjustment effort, our adjusted data set results on average in slightly greater warm season and lower cold season precipitation increases, greater precipitation increases over North America, and lower precipitation increases over Eurasia.

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Section: Determination Of Crs For Canadamentioning

confidence: 99%

Section: Determination Of Crs For Canadamentioning

confidence: 99%

Adjustment of global gridded precipitation for systematic bias

2003

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“…Incoming longwave radiation was not measured and was estimated from an empirical approach following Idso (1981) and Sellers (1965) using observations of hourly air temperature, relative humidity, cloud type and opacity. Hourly precipitation rate data were derived from 6-hourly precipitation totals observed with a Nipher-shielded gauge corrected for windinduced undercatch, wetting loss and trace precipitation amounts following Metcalfe et al (1997) and Goodison et al (1998). Hourly precipitation intensity and phase were derived using a weighting scheme based on synoptic reports of precipitation type and intensity.…”

Section: B Goose Bay (Gsb)mentioning

confidence: 99%

Evaluation of snow cover in CLASS for SnowMIP

et al. 2006

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“…Uncovering steps, or discontinuities, in the time series of various observed climatological elements is not a new concept. Biases were studied in the past (Metcalf et al, 1997), and information about their magnitude was used to adjust long-term precipitation records, for example when new types of manual rain gauges were introduced (Mekis and Hogg, 1999). Such biases due to changing instrumentation can be easily uncovered in straightforward laboratory or field tests, where all instruments are located side-by-side in a common compound.…”

Section: La Présente éTude a Fait Ressortir L'importance De Disposer mentioning

confidence: 99%

“…Trace is reported for any amounts less than 0.2 mm. Small losses exist due to wetting of the funnel and wind undercatch (Metcalf et al, 1997). The Nipher snow gauge and Standard Snow Ruler have a resolution of at least 0.2 cm.…”

Section: Instr Bias Removedmentioning

confidence: 99%