A two-layer canopy model with thermal inertia for an improved snowpack energy balance below needleleaf forest (model SNOWPACK, version 3.2.1, revision 741)

Gouttevin, Isabelle; Lehning, Michael; Jonas, Tobias; Gustafsson, David; Mölder, Meelis

doi:10.5194/gmd-8-2379-2015

Cited by 51 publications

(78 citation statements)

References 74 publications

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“…[] suggest that ground sublimation in regions with relatively high solar elevation angles and many cloud‐free days would be particularly sensitive to increased shortwave radiation upon the removal of the canopy by wildfire. Longwave radiation is also important to the snowpack energy budget [ Meromy et al ., ; Gouttevin et al ., ]. Changes in forest cover density may result in greater changes in incoming longwave radiation than changes in shortwave radiation during conditions of low solar elevation angle, low atmospheric emissivities, and high snow albedos [ Lundquist et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Canopy effects on snow sublimation from a central Arizona Basin

Svoma

2017

JGR Atmospheres

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Guided by 30 m terrain and forest cover data, snow sublimation from the Salt River basin in the Southwest U.S. is simulated for years 2008 (wet year) and 2007 (dry year). Downscaled meteorological input correlates well (r~0.80) with independent observations at AmeriFlux sites. Additionally, model correlation and bias with eddy‐covariance vapor flux observations is comparable to previous localized modeling efforts. Upon a 30% reduction in effective leaf area index, canopy sublimation decreases by 1.29 mm (27.0%) and 1.05 mm (23.0%) at the basin scale for the 2008 and 2007 simulations, respectively. Ground sublimation decreases 0.72 mm (4.75%) in 2008 and only 0.17 mm (1.5%) in 2007. Canopy snow‐holding capacity and frequent unloading events at lower elevations limit the variability in canopy sublimation from wet year to dry year at the basin scale. The greater decrease in snowpack sublimation in the wet year is partly due to decreased longwave radiation from the canopy reduction over a more extensive snowpack than the dry year. This decrease overcomes the increased solar radiation and wind speed during winter. A second factor is that a greater extent of the snowpack persisted into spring in 2008 than 2007, and the large increase in shortwave flux upon canopy reduction increases melt rates, reducing duration. Only in heavily forested high elevations (>2900 m above sea level) in 2008 does the snowpack persist long enough into spring to result in increased ground sublimation upon canopy reduction. As forest cover change can occur rapidly, these results are critical from water resource and ecosystem function perspectives.

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Section: Introductionmentioning

confidence: 99%

Canopy effects on snow sublimation from a central Arizona Basin

Svoma

2017

JGR Atmospheres

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“…The specific heat capacity of the soil solids was set to 800 J kg −1 ·K −1 and the thermal conductivity of the soil to 0.9 W m −1 ·K −1 (Waples & Waples, ). The roughness length of snow was set equal to 0.001 m. The canopy module of SNOWPACK modifies sensible and latent heat fluxes to account for roughness created by trees (Gouttevin et al, ), removing the need to increase the roughness of the snow surface to account for the overlying canopy. Mean canopy height on the hillslope was estimated to be 19 m using LiDAR data obtained for the field site in 2014 and the method outlined by Nӕsset ().…”

Section: Methodsmentioning

confidence: 99%

“…Outside of these user‐input parameters, SNOWPACK was not calibrated for No Name, and default settings were used. See Bartelt and Lehning (), Lehning et al (, ), Gouttevin et al (), Wever et al (), and Wever et al () for detailed descriptions of the model and default parameters.…”

Section: Methodsmentioning

confidence: 99%

Analysis of snowpack dynamics during the spring melt season for a sub‐alpine site using point measurements and numerical modeling

Pleasants

Kelleners

Ohara

2017

Hydrological Processes

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Snowpack dynamics through October 2014–June 2017 were described for a forested, sub‐alpine field site in southeastern Wyoming. Point measurements of wetness and density were combined with numerical modeling and continuous time series of snow depth, snow temperature, and snowpack outflow to identify 5 major classes of distinct snowpack conditions. Class (i) is characterized by no snowpack outflow and variable average snowpack temperature and density. Class (ii) is characterized by short durations of liquid water in the upper snowpack, snowpack outflow values of 0.0008–0.005 cm hr−1, an increase in snowpack temperature, and average snow density between 0.25–0.35 g cm−3. Class (iii) is characterized by a partially saturated wetness profile, snowpack outflow values of 0.005–0.25 cm hr−1, snowpack temperature near 0 °C, and average snow density between 0.25–0.40 g cm−3. Class (iv) is characterized by strong diurnal snowpack outflow pattern with values as high as 0.75 cm hr−1, stable snowpack temperature near 0 °C, and stable average snow density between 0.35–0.45 g cm−3. Class (v) occurs intermittently between Classes (ii)–(iv) and displays low snowpack outflow values between 0.0008–0.04 cm hr−1, a slight decrease in temperature relative to the preceding class, and similar densities to the preceding class. Numerical modeling of snowpack properties with SNOWPACK using both the Storage Threshold scheme and Richards' equation was used to quantify the effect of snowpack capillarity on predictions of snowpack outflow and other snowpack properties. Results indicate that both simulations are able to predict snow depth, snow temperature, and snow density reasonably well with little difference between the 2 water transport schemes. Richards' equation more accurately simulates the timing of snowpack outflow over the Storage Threshold scheme, especially early in the melt season and at diurnal timescales.

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“…Although Monin-Obukhov similarity theory options are available, this stability correction generally performed worse relative to the bulk Richardson number in our preliminary simulations as well as in the work of others (Essery et al, 5 2013). Additionally, the two-layer SNOWPACK canopy module (Gouttevin et al, 2015) was activated for the subalpine simulations. Parameters for the canopy module were calibrated using a series of 100 Monte Carlo simulations with value ranges bounded by representative estimates of leaf area index, vegetation height, direct canopy throughfall, and wind speed reduction.…”

Section: Model Description 15mentioning

confidence: 99%

Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget

Jennings¹,

Kittel²,

Molotch³

2017

Preprint

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Abstract.Cold content is a measure of a snowpack's energy deficit and is a linear function of snowpack mass and temperature. Positive energy fluxes into a snowpack must first satisfy the remaining energy deficit before snowmelt runoff 10 begins, making cold content a key component of the snowpack energy budget. Nevertheless, uncertainty surrounds cold content development and its relationship to snowmelt, likely because of a lack of direct observations. This work clarifies the controls exerted by air temperature, precipitation, and negative energy fluxes on cold content development and quantifies the relationship between cold content and snowmelt timing and rate at daily to seasonal time scales. The analysis presented herein leverages a unique long-term snow pit record along with validated output from the SNOWPACK model forced with 15 23 water years (1991-2013) of quality controlled, infilled hourly meteorological data from an alpine and subalpine site in the Colorado Rocky Mountains. The results indicated that precipitation exerted the primary control on cold content development with snowfall responsible for 84.4% and 73.0% of simulated gains in the alpine and subalpine, respectively. A negative surface energy balance-primarily driven by sublimation and longwave radiation emission from the snowpack-during dry periods provided a secondary pathway for cold content development, and was responsible for the remaining 15.6% and 20 27.0% of cold content additions. Non-zero cold content values were associated with reduced snowmelt rates and delayed snowmelt onset at daily to sub-seasonal time scales. These results suggest that the information provided by cold content observations and/or simulations is most relevant to snowmelt processes at shorter time scales, and may help water resource managers to better predict melt onset and rate.

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A two-layer canopy model with thermal inertia for an improved snowpack energy balance below needleleaf forest (model SNOWPACK, version 3.2.1, revision 741)

Cited by 51 publications

References 74 publications

Canopy effects on snow sublimation from a central Arizona Basin

Canopy effects on snow sublimation from a central Arizona Basin

Analysis of snowpack dynamics during the spring melt season for a sub‐alpine site using point measurements and numerical modeling

Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget

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