Chinooks and winter evaporation

Nkemdirim, Lawrence C.

doi:10.1007/bf00867470

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…Evidence suggests that surface interaction and memory play significant roles in the relationship. It has been shown previously that if the energy advected into the belt by the wind is held constant, the longer a chinook lasts, the warmer the surface air temperature gets (Nkemdirim, 1991(Nkemdirim, , 1995.…”

Section: Chinookfrequencymentioning

confidence: 99%

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Canada's Chinook Belt

Nkemdirim

1996

Int. J. Climatol.

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The chinook is the best example of the family of mountain winds that blows in regions where long mountain chains lie more or less at right angles to the prevailing wind. Apart from the unseasonable warmth it brings to Canada's interior in winter, it represents an efficient system through which latent heat drawn from the Pacific coast is converted into sensible heat and transported zonally across the continent. It also compromises both the physical and human environments. The severity of impacts depends on either the amount of anomalous warming experienced or on the number of chinook events occurring over a winter, and often on both. In Canada, the chinook belt lies almost exclusively in southern Alberta. In this paper, the belt is described and mapped with respect to the strength of the wind's temperature signal and numerical frequency. The temperature signal (the signal) is the difference between the highest temperature attained during a chinook event and the daily maximum. The frequency is the number of days in the winter with, at least, 1 h of chinook wind. Mean point values of the signal range from 13 to 25 K. Mean seasonal frequency varies from 43 days to 52 days per winter. The core of the belt for temperature and frequency do not coincide. The highest frequencies occur in the Crowsnest Pass area whereas the strongest signals are found further east of the mountains in an axis that includes Vauxhall and Brooks. Both signal strengths and frequency show strong decadal variations. The 1980s were chinook rich; the 1970s were chinook poor.

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Section: Chinookfrequencymentioning

confidence: 99%

“…It melts the winter snowpack thereby denying the rivers and the soil of the moisture that should enrich them early in the spring (Steed, 1982). It dries out the top soil, and in so doing, can become a factor in wind erosion (Nkemdirim, 1991). It is a grass and forest fire hazard (Nkemdirim, 1987).…”

Section: Introductionmentioning

confidence: 99%

Canada's Chinook Belt

Nkemdirim

1996

Int. J. Climatol.

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“…The strong winter co-occurrence of soil moisture and wind speed in southern Alberta is best explained as driven by Chinook events. Chinooks bring warm-dry-high-speed winds that have the ability to melt snow and thaw the upper layers of soil [14], snow melt that is not evaporated can infiltrate into the thawed upper soil layers. Maximum air temperature and wind speed were not as strongly correlated as wind speed and soil moisture during the winter, 0.66 at Onefour to 0.89 at Oyen with an average correlation of 0.71 (Table 5).…”

Section: Resultsmentioning

confidence: 99%

“…The warm moisture-deprived air has the ability to quickly melt and evaporate any snow cover, while thawing the upper layers of the soil. Temperatures during a Chinook event can increase air temperatures by more than 20˚C in a few hours [14]. A Chinook can last only a matter of hours to more than 24 hours.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variability of soil freeze-thaw cycling across Southern Alberta, Canada

Phillips¹,

Newlands²

2011

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Soil freeze-thaw cycles play an important role in all aspects of agro-ecosystems, such as crop productivity, the evolution of the soil matrix, including trace-gas emissions. In regions that experience synoptic weather conditions throughout the winter, freeze-thaw cycles generally occur in one of two categories; seasonal or winter cycles. Current soil vegetation atmosphere models (SVAT's) often include a heat-transport soil freeze-thaw algorithm, but lack detail on complex interactions between the main driving variables. Boundary conditions for these models are often based only on a few climate variables and typically lack regional context. A nested statistical analysis was applied to identify the optimal set of environmental variables (via a stepwise regression selection procedure) to track soil freeze-thaw dynamics. Historical data collected between the years 2006-2009, for 17 long-term climate stations distributed across southern Alberta Canada was utilized. Cross-correlation between wind speed and maximum air temperature identified Chinook-driven freeze-thaw events, with such interaction varying significantly across the region and by soil depth. Climate-soil interactions were most significant predictors of soil temperature during winter months. The seasonal freeze-thaw cycle is estimated to vary between 112 -131 days, consisting of 12 -20 winter cycles (1 cm depth), and 1-5 winter cycles (5 cm depth) with average lag time of 26 -112 days. Freeze-thaw prediction was greatly improved when higher-order climate interaction terms were considered. Our findings highlight the importance of soil-water assumeptions within complex ecosystem SVAT models in resolving regional-driven climatic trends. Alongside improved representation of regional trends aimed at reducing model-based uncertainty, such efforts are expected to, in tandem, help advance the geostatistical design, and implementation of agroenvironmental monitoring systems that combine in-situ and satellite/remotesensing derived estimates of near-surface soil moisture.

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An empirical relationship between temperature, vapour pressure deficit and wind speed and evaporation during a winter chinook

Nkemdirim

1991

Theor Appl Climatol

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Chinooks and winter evaporation

Cited by 8 publications

References 13 publications

Canada's Chinook Belt

Canada's Chinook Belt

Spatial and temporal variability of soil freeze-thaw cycling across Southern Alberta, Canada

An empirical relationship between temperature, vapour pressure deficit and wind speed and evaporation during a winter chinook

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