Cold Air Drainage on a Forested Mountain Slope

Bergen, James D.

doi:10.1175/1520-0450(1969)008<0884:cadoaf>2.0.co;2

Cited by 31 publications

(13 citation statements)

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“…In wet sites, radiant energy in the morning dries surfaces before it warms them, leading to significantly cooler maximum daily temperatures in wetter locations (Dai et al 1999). In contrast, minimum daily temperatures vary according to how cold air moves across land surfaces (katabatic winds) and are only indirectly related to daytime radiation (Bergen 1969;Manins and Sawford 1979). The absence of direct radiation at night increases the importance of heat losses from longwave radiation, which is influenced by slope angle and the presence of overhead vegetation, and radiating heat gains from the ground, which in part connect nighttime and daytime temperatures.…”

Section: Spatial Modeling: Predictor Variablesmentioning

confidence: 99%

Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

Fridley

2009

Journal of Applied Meteorology and Climatology

181

219

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Landscape-driven microclimates in mountainous terrain pose significant obstacles to predicting the response of organisms to atmospheric warming, but few if any studies have documented the extent of such finescale variation over large regions. This paper demonstrates that ground-level temperature regimes in Great Smoky Mountains National Park (Tennessee and North Carolina) vary considerably over fine spatial scales and are only partially linked to synoptic weather patterns and environmental lapse rates. A 120-sensor network deployed across two watersheds in 2005-06 exhibited finescale (,1000-m extent) temperature differences of over 28C for daily minima and over 48C for daily maxima. Landscape controls over minimum temperatures were associated with finescale patterns of soil moisture content, and maximum temperatures were associated with finescale insolation differences caused by topographic exposure and vegetation cover. By linking the sensor array data to 10 regional weather stations and topographic variables describing site radiation load and moisture content, multilevel spatial models of 30-m resolution were constructed to map daily temperatures across the 2090-km 2 park, validated with an independent 50-sensor network. Maps reveal that different landscape positions do not maintain relative differences in temperature regimes across seasons. Near-stream locations are warmer in the winter and cooler in the summer, and sites of low elevation more closely track synoptic weather patterns than do wetter high-elevation sites. This study suggests a strong interplay between near-ground heat and water balances and indicates that the influence of past and future shifts in regional temperatures on the park's biota may be buffered by soil moisture surfeits from high regional rainfall.

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Section: Spatial Modeling: Predictor Variablesmentioning

confidence: 99%

Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

Fridley

2009

Journal of Applied Meteorology and Climatology

181

219

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“…Air mass trajectory calculations, as well as surface wind-field correlations, support this interpretation. A detailed discussion of the local meteorology with an emphasis on the C-1 site can be found elsewhere (Bergen, 1969;Barry, 1972;Hansen et al, 1978;Greenland, 1980;Barry, 1981).…”

Section: Location and Instrumentationmentioning

confidence: 99%

A study of ozone in the Colorado mountains

et al. 1983

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The seasonal and diurnal variations of ozone mixing ratios have been observed at Niwot Ridge, Colorado. The ozone mixing ratios have been correlated with the NOx(NO +NO2) mixing ratios measured concurrently at the site. The seasonal and diurnal variations in 03 can be reasonably well understood by considering photochemistry and transport, In the winter there is no apparent systematic diurnal variation in the 03 mixing ratio because there is little diurnal change of transport and a slow photochemistry. In the summer, the 03 levels at the site are suppressed at night due to the presence of a nocturnal inversion layer that isolates ozone near the surface, where it is destroyed. Ozone is observed to increase in the summer during the day. The increases in ozone correlate with increasing NO~ levels, as well as with the levels of other compounds of anthropogenic origin. We interpret this correlation as in-situ or in-transit photochemical production of ozone from these precursors that are transported to our site. The levels of ozone recorded approach 100 ppbv at NOt mixing ratios of approximately 3 ppbv. Calculations made using a simple clean tropospheric chemical model are consistent with the NOxrelated trend observed for the daytime ozone mixing ratio. However, the chemistry, which does not include nonmethane hydrocarbon photochemistry, underestimates the observed 03 production.

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“…In well defined valleys, thermally induced upslope and downslope flows as well as mountain-valley winds can occur. However, even less is known about the effects of trees on these air circulations (Bergen, 1969).…”

Section: Introductionmentioning

confidence: 99%

Some effects of deforestation on nocturnal drainage flow and local climate ? A numerical study

Groß

1987

Boundary-Layer Meteorol

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The three-dimensional mesoscale mode1 FITNAH has been modified to simulate effects of a tall tree canopy on airflow in complex terrain. Numerical experiments show the general features of meteorological variables inside a plant stand with low wind speeds and a nearly neutral thermal stratification during night. Available observations from the Finkenbach valley and the simulated temperatures near the ground show good agreeement.Comparison ofmodel results for a nighttime situation for cases with and without a canopy (after complete deforestation) leads to the main results, viz., that surface wind speed will increase and the atmosphere near the ground will become colder after deforestation.However, the production rate of cooled air (expressed in m3 m-* h-') decreases; that means that forested slopes are more effective in ventilating a city than slopes covered with short vegetation.

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Cold Air Drainage on a Forested Mountain Slope

Cited by 31 publications

References 0 publications

Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

A study of ozone in the Colorado mountains

Some effects of deforestation on nocturnal drainage flow and local climate ? A numerical study

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Cold Air Drainage on a Forested Mountain Slope

Cited by 31 publications

References 0 publications

Downscaling Climate over Complex Terrain: High Finescale (&lt;1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

Downscaling Climate over Complex Terrain: High Finescale (&lt;1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

A study of ozone in the Colorado mountains

Some effects of deforestation on nocturnal drainage flow and local climate ? A numerical study

Contact Info

Product

Resources

About

Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*