Longwave Radiation in Mountainous Areas and Its Influence on the Energy Balance of Alpine Snowfields

Olyphant, Greg A.

doi:10.1029/wr022i001p00062

Cited by 59 publications

(32 citation statements)

References 10 publications

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“…An assumption of Equation (2) is that the sky longwave radiation is not affected by terrain. In rugged terrain, the incoming longwave radiation is significantly increased by adjacent terrain, thus producing spatial variability in snowmelt (Olyphant 1986;Sicart 2006). Thus, incoming longwave radiation to snow beneath forest canopies can be calculated according to three methods based on different assumptions, data and parameter requirements.…”

Section: Incoming Longwave Radiation Modelingmentioning

confidence: 99%

“…The incoming longwave radiation beneath forest canopies was generally calculated with air temperature, sky view factor, the incoming longwave, and shortwave radiation above forest canopies (Price and Petzold 1984;Essery et al 2008;Pomeroy et al 2009). However, the longwave and shortwave radiation may be changed by adjacent rugged terrain (Olyphant 1986;Sicart et al 2006;Tian et al 2007).…”

Section: Introductionmentioning

confidence: 97%

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Observations and modeling of incoming longwave radiation to snow beneath forest canopies in the west Tianshan Mountains, China

Wang

Liu

et al. 2014

J. Mt. Sci.

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Forest canopy reduces shortwave radiation and increases the incoming longwave radiation to snowpacks beneath forest canopies. Furthermore, the effect of forest canopy may be changed by complex topography. In this paper, we measured and simulated the incoming longwave radiation to snow beneath forest at different canopy openness in the west Tianshan Mountains, China (43°16'N, 84°24'E) during spring 2013. A sensitivity study was conducted to explore the way that terrain influenced the incoming longwave radiation to snow beneath forest canopies. In the simulation model, measurement datasets, including air temperature, incoming shortwave radiation above canopy, and longwave radiation enhanced by adjacent terrain, were applied to calculate the incoming longwave radiation to snow beneath forest canopy. The simulation results were consistent with the measurements on hourly scale and daily scale. The effect of longwave radiation enhanced by terrain was important than that of shortwave radiation above forest canopy with different openness except the 20% canopy openness. The longwave radiation enhanced due to adjacent terrain increases with the slope increase and temperature rise. When air temperature (or slope) is relatively low, the longwave radiation enhanced by adjacent terrain is not sensitive to slope (or air temperature), but the sensitivity increases with the decrease of snow cover area on sunny slope. The effect of longwave radiation is especially sensitive when the snow cover on sunny slope melts completely. The effect of incoming shortwave radiation reflected by adjacent terrain on incoming longwave radiation to snow beneath forest canopies is more slight than that of the enhanced longwave radiation.

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Section: Incoming Longwave Radiation Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Observations and modeling of incoming longwave radiation to snow beneath forest canopies in the west Tianshan Mountains, China

Wang

Liu

et al. 2014

J. Mt. Sci.

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show abstract

“…We ignored for the time being potentially predictable variation due to steep terrain effects (e.g. avalanches), large-scale wind effects, saturated soils, geothermal activity, and longwave radiation from surrounding cliffs (Olyphant, 1986). However, we were able to map the likely location of these effects and define the sampling domain to avoid them.…”

Section: Stratified Nested Design For Sampling Swe Fixed and Random Ementioning

confidence: 99%

Optimal sampling schemes for estimating mean snow water equivalents in stratified heterogeneous landscapes

Watson

Anderson

Newman

et al. 2006

Journal of Hydrology

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“…In rugged terrain, ground emissions enhance longwave irradiance, producing a spatial variability in snowmelt (e.g. Olyphant, 1986).…”

Section: Introductionmentioning

confidence: 99%

Incoming longwave radiation to melting snow: observations, sensitivity and estimation in Northern environments

Sicart

Pomeroy

Essery

et al. 2006

Hydrological Processes

168

149

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Abstract:At high latitudes, longwave radiation can provide similar, or higher, amounts of energy to snow than shortwave radiation due to the low solar elevation (cosine effect and increased scattering due to long atmospheric path lengths). This effect is magnified in mountains due to shading and longwave emissions from the complex topography. This study examines longwave irradiance at the snow surface in the Wolf Creek Research Basin, Yukon Territory, Canada (60°36 0 N, 134°57 0 W) during the springs of 2002 and 2004. Incoming longwave radiation was estimated from standard meteorological measurements by segregating radiation sources into clear sky, clouds and surrounding terrain. A sensitivity study was conducted to detect the atmospheric and topographic conditions under which emission from adjacent terrain significantly increases the longwave irradiance. The total incoming longwave radiation is more sensitive to sky view factor than to the temperature of the emitting terrain surfaces. Brutsaert's equation correctly simulates the clear-sky irradiance for hourly time steps using temperature and humidity. Longwave emissions from clouds, which raised longwave radiation above that from clear skies by 16% on average, were best estimated using daily atmospheric shortwave transmissivity and hourly relative humidity. An independent test of the estimation procedure for a prairie site near Saskatoon, Saskatchewan, Canada, indicated that the calculations are robust in late winter and spring conditions.

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Longwave Radiation in Mountainous Areas and Its Influence on the Energy Balance of Alpine Snowfields

Cited by 59 publications

References 10 publications

Observations and modeling of incoming longwave radiation to snow beneath forest canopies in the west Tianshan Mountains, China

Observations and modeling of incoming longwave radiation to snow beneath forest canopies in the west Tianshan Mountains, China

Optimal sampling schemes for estimating mean snow water equivalents in stratified heterogeneous landscapes

Incoming longwave radiation to melting snow: observations, sensitivity and estimation in Northern environments

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