Observations of urban snow properties in Calgary, Canada

Ho, Carrie Lee Ing; Valeo, Caterina

doi:10.1002/hyp.5544

Cited by 18 publications

(7 citation statements)

References 20 publications

(43 reference statements)

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“…Urban snowmelt has also been shown to be influenced by longwave radiation emitted from buildings with high emissivity values and the relatively lower albedo of the surrounding urban surfaces [Lemonsu et al, 2008;Leroyer et al, 2010;Bergeron and Strachan, 2012]. Urban snow typically is cleared from parking lots, roads, and sidewalks and gathered in large piles [Järvi et al, 2014], where it can become packed and mixed with gravel and dirt, significantly lowering its albedo [Bengtsson and Westerström, 1992;Ho and Valeo, 2005]. The effect of road salt on evaporation within cities is complex.…”

Section: 1002/2016jd026074mentioning

confidence: 99%

Urban emissions of water vapor in winter

et al. 2017

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Elevated water vapor (H2Ov) mole fractions were occasionally observed downwind of Indianapolis, IN, and the Washington, D.C.‐Baltimore, MD, area during airborne mass balance experiments conducted during winter months between 2012 and 2015. On days when an urban H2Ov excess signal was observed, H2Ov emission estimates range between 1.6 × 104 and 1.7 × 105 kg s−1 and account for up to 8.4% of the total (background + urban excess) advected flow of atmospheric boundary layer H2Ov from the urban study sites. Estimates of H2Ov emissions from combustion sources and electricity generation facility cooling towers are 1–2 orders of magnitude smaller than the urban H2Ov emission rates estimated from observations. Instances of urban H2Ov enhancement could be a result of differences in snowmelt and evaporation rates within the urban area, due in part to larger wintertime anthropogenic heat flux and land cover differences, relative to surrounding rural areas. More study is needed to understand why the urban H2Ov excess signal is observed on some days, and not others. Radiative transfer modeling indicates that the observed urban enhancements in H2Ov and other greenhouse gas mole fractions contribute only 0.1°C d−1 to the urban heat island at the surface. This integrated warming through the boundary layer is offset by longwave cooling by H2Ov at the top of the boundary layer. While the radiative impacts of urban H2Ov emissions do not meaningfully influence urban heat island intensity, urban H2Ov emissions may have the potential to alter downwind aerosol and cloud properties.

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Section: 1002/2016jd026074mentioning

confidence: 99%

Urban emissions of water vapor in winter

et al. 2017

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“…Furthermore, the evolution of temperature and water content of the snowpack also influences the turbulent fluxes. Some hydrological studies have documented the snow in urban environments (Ho and Valeo 2005), as well as urban snowmelt and urban flow rates. These studies pointed out the impact of snowmelt during springtime floods (Thorolfsson and Brandt 1996;Semádeni-Davies and Bengtsson 1998).…”

Section: Introductionmentioning

confidence: 99%

Overview and First Results of the Montreal Urban Snow Experiment 2005

Lemonsu

Bélair

Mailhot

et al. 2008

Journal of Applied Meteorology and Climatology

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Within the framework of a large urban meteorology program recently launched in Canada, the Montreal Urban Snow Experiment (MUSE) campaign has been conducted in order to document the thermoradiative exchanges in a densely built-up area of Montreal in late winter and spring conditions. The targeted period is of particular scientific interest because it covers the transition period from a mainly snow-covered urban environment to a mainly snow-free environment. The campaign is based on four weeks of observations from 17 March to 14 April 2005. It couples automatic and continuous measurements of radiation and turbulent fluxes, radiative surface temperatures, and air temperature and humidity with manual observations performed during intensive observation periods to supplement the surface temperature observations and to characterize the snow properties. The footprints of radiation and turbulent flux measurements are computed using the surface-sensor-sun urban model and the flux-source area model, respectively. The analysis of the radiometer footprint underscores the difficulty of correctly locating this type of instrument in urban environments, so that the sensor sees a representative combination of the urban and nonurban surfaces. Here, the alley contribution to the upward radiation tends to be overestimated to the detriment of the road contribution. The turbulent footprints cover homogeneous zones in terms of surface characteristics, whatever the wind direction. The initial analysis of the energy balance displays the predominance of the residual term (Q Res ϭ Q* Ϫ Q H Ϫ Q E ) in comparison with the turbulent sensible (Q H ) and latent (Q E ) heat fluxes, since its daytime contribution exceeds 50% of the net radiation (Q*). The investigation of energy balances observed at the beginning and at the end of the experiment (i.e., with and without snow) also indicates that the snow plays a significant role in the flux partitioning and the daily pattern of fluxes. Without snow, the energy balance is characteristic of energy balances that have been already observed in densely built-up areas, notably because of the hysteresis observed for Q Res and Q H in relation to Q* and because of the high contribution of Q Res , which includes the effect of heat storage inside the urban structures. With snow, the flux partitioning is modified by the snowmelt process leading to contributions of the residual term and latent heat flux, which are larger than in the case without snow to the detriment of the sensible heat flux.

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“…The characteristics of snow in the streets were observed to be quite variable from one location to another (Ho 2002;Ho and Valeo 2005). Snow cover and properties were found to be more homogeneous in the alleys than in the streets, where human activities disturb the snowpack.…”

Section: A Muse 2005mentioning

confidence: 98%

Evaluation of the Town Energy Balance Model in Cold and Snowy Conditions during the Montreal Urban Snow Experiment 2005

Lemonsu

Bélair

Mailhot

et al. 2010

Journal of Applied Meteorology and Climatology

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Using the Montreal Urban Snow Experiment (MUSE) 2005 database, surface radiation and energy exchanges are simulated in offline mode with the Town Energy Balance (TEB) and the Interactions between Soil, Biosphere, and Atmosphere (ISBA) parameterizations over a heavily populated residential area of Montreal, Quebec, Canada, during the winter-spring transition period (from March to April 2005). The comparison of simulations with flux measurements indicates that the system performs well when roads and alleys are snow covered. In contrast, the storage heat flux is largely underestimated in favor of the sensible heat flux at the end of the period when snow is melted. An evaluation and an improvement of TEB's snow parameterization have also been conducted by using snow property measurements taken during intensive observational periods. Snow density, depth, and albedo are correctly simulated by TEB for alleys where snow cover is relatively homogeneous. Results are not as good for the evolution of snow on roads, which is more challenging because of spatial and temporal variability related to human activity. An analysis of the residual term of the energy budget-including contributions of snowmelt, heat storage, and anthropogenic heat-is performed by using modeling results and observations. It is found that snowmelt and anthropogenic heat fluxes are reasonably well represented by TEB-ISBA, whereas storage heat flux is underestimated.

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Observations of urban snow properties in Calgary, Canada

Cited by 18 publications

References 20 publications

Urban emissions of water vapor in winter

Urban emissions of water vapor in winter

Overview and First Results of the Montreal Urban Snow Experiment 2005

Evaluation of the Town Energy Balance Model in Cold and Snowy Conditions during the Montreal Urban Snow Experiment 2005

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