Snow surface albedo estimation using terrestrial photography

Corripio, Javier G.

doi:10.1080/01431160410001709002

Cited by 151 publications

(162 citation statements)

References 30 publications

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“…The focal length, the camera rotation, and the terrain coordinate of the image centre pixel are inferred by optimizing the match between the control points in the image and the terrain. The video image is registered with a ray tracing technique, resulting in a transfer function between each image pixel and each pixel of the digital terrain model [Corripio, 2004]. Thus, information on the terrain, such as elevation and radar ranges, can be transferred into the video images, and features identified in the videos like avalanche contours can be mapped on to the terrain with the reverse transformation.…”

Section: Videomentioning

confidence: 99%

The dynamics of surges in the 3 February 2015 avalanches in Vallée de la Sionne

Köhler¹,

McElwaine

Sovilla³

et al. 2016

JGR Earth Surface

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Five avalanches were artificially released at the Vallée de la Sionne test site in the west of Switzerland on 3 February 2015 and recorded by the GEOphysical flow dynamics using pulsed Doppler radAR Mark 3 radar system. The radar beam penetrates the dilute powder cloud and measures reflections from the underlying denser avalanche features allowing the tracking of the flow at 111 Hz with 0.75 m downslope resolution. The data show that the avalanches contain many internal surges. The large or “major” surges originate from the secondary release of slabs. These slabs can each contain more mass than the initial release, and thus can greatly affect the flow dynamics, by unevenly distributing the mass. The small or “minor” surges appear to be a roll wave‐like instability, and these can greatly influence the front dynamics as they can repeatedly overtake the leading edge. We analyzed the friction acting on the fronts of minor surges using a Voellmy‐like, simple one‐dimensional model with frictional resistance and velocity‐squared drag. This model fits the data of the overall velocity, but it cannot capture the dynamics and especially the slowing of the minor surges, which requires dramatically varying effective friction. Our findings suggest that current avalanche models based on Voellmy‐like friction laws do not accurately describe the physics of the intermittent frontal region of large mixed avalanches. We suggest that these data can only be explained by changes in the snow surface, such as the entrainment of the upper snow layers and the smoothing by earlier flow fronts.

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Section: Videomentioning

confidence: 99%

The dynamics of surges in the 3 February 2015 avalanches in Vallée de la Sionne

Köhler¹,

McElwaine

Sovilla³

et al. 2016

JGR Earth Surface

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“…This day was cloudfree, had no meteorological instrument failures, and had an uniform snowcover. The set of hourly images were orthorectified using the algorithm and software of Corripio (2004). Orthorectification transforms georeferenced, oblique photographs into quasi-airphotos by defining a mapping function between the image and the DEM by performing a perspective transform on the DEM (Corripio, 2004 to errors in the orthorectification process.…”

Section: Orthorectification Of Timelapse Imagerymentioning

confidence: 99%

“…The set of hourly images were orthorectified using the algorithm and software of Corripio (2004). Orthorectification transforms georeferenced, oblique photographs into quasi-airphotos by defining a mapping function between the image and the DEM by performing a perspective transform on the DEM (Corripio, 2004 to errors in the orthorectification process. Throughout the season, the camera housing would move and flex (such as during a storm), and these slight changes resulted in the need to use a trial-and-error process to obtain appropriate orthorectification.…”

Section: Orthorectification Of Timelapse Imagerymentioning

confidence: 99%

“…In many environments, such as lowand mid-latitude glaciers and high alpine terrain, shortwave fluxes dominate the surface energy balance, and for snow-covered surfaces it is often the main source of energy for melt (Gray and Male, 1981;Corripio, 2004). Given the importance of shortwave fluxes, correctly estimating the incoming shortwave solar radiation incident to a surface in complex terrain, both spatially and temporally, is necessary to model dependent processes.…”

Section: Introductionmentioning

confidence: 99%

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Implications of mountain shading on calculating energy for snowmelt using unstructured triangular meshes

Marsh

Pomeroy

Spiteri

2012

Hydrological Processes

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In many parts of the world, the snowmelt energy balance is dominated by net solar shortwave radiation. This is the case in the Canadian Rocky Mountains, where clear skies dominate the winter and spring. In mountainous regions, solar irradiance at the snow surface is not only affected by solar angles, atmospheric transmittance, and the slope and aspect of immediate topography, but also by shadows from surrounding terrain. Many hydrological models do not consider such horizon-shadows. The accumulation of errors in estimating solar irradiance by neglecting horizon-shadows can lead to significant errors in calculating the timing and rate of snowmelt due to the seasonal storage of internal energy in the snowpack.A common approach to representing the landscape is through structured meshes. iii

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“…Consequently, several studies have assessed the spatiotemporal variations in surface albedo using ground-based measurements (e.g., Arendt, 1999;Brock, 2004;Brock et al, 2000;Pirazzini, 2004), albedo data derived from satellite data (Dumont et al, 2012;Klok et al, 2003;Stroeve et al, 2006) or terrestrial photography (Corripio, 2004;Dumont et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Albedo over rough snow and ice surfaces

2014

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Abstract. Both satellite and ground-based broadband albedo measurements over rough and complex terrain show several limitations concerning feasibility and representativeness. To assess these limitations and understand the effect of surface roughness on albedo, firstly, an intrasurface radiative transfer (ISRT) model is combined with albedo measurements over different penitente surfaces on Glaciar Tapado in the semiarid Andes of northern Chile. Results of the ISRT model show effective albedo reductions over the penitentes up to 0.4 when comparing the rough surface albedo relative to the albedo of the flat surface. The magnitude of these reductions primarily depends on the opening angles of the penitentes, but the shape of the penitentes and spatial variability of the material albedo also play a major role.Secondly, the ISRT model is used to reveal the effect of using albedo measurements at a specific location (i.e., apparent albedo) to infer the true albedo of a penitente field (i.e., effective albedo). This effect is especially strong for narrow penitentes, resulting in sampling biases of up to ±0.05. The sampling biases are more pronounced when the sensor is low above the surface, but remain relatively constant throughout the day. Consequently, it is important to use a large number of samples at various places and/or to locate the sensor sufficiently high in order to avoid this sampling bias of surface albedo over rough surfaces.Thirdly, the temporal evolution of broadband albedo over a penitente-covered surface is analyzed to place the experiments and their uncertainty into a longer temporal context. Time series of albedo measurements at an automated weather station over two ablation seasons reveal that albedo decreases early in the ablation season. These decreases stabilize from February onwards with variations being caused by fresh snowfall events. The 2009/2010 and 2011/2012 seasons differ notably, where the latter shows lower albedo values caused by larger penitentes. Finally, a comparison of the ground-based albedo observations with Landsat and MODIS (Moderate Resolution Imaging Spectroradiometer)-derived albedo showed that both satellite albedo products capture the albedo evolution with root mean square errors of 0.08 and 0.15, respectively, but also illustrate their shortcomings related to temporal resolution and spatial heterogeneity over small mountain glaciers.

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Snow surface albedo estimation using terrestrial photography

Cited by 151 publications

References 30 publications

The dynamics of surges in the 3 February 2015 avalanches in Vallée de la Sionne

The dynamics of surges in the 3 February 2015 avalanches in Vallée de la Sionne

Implications of mountain shading on calculating energy for snowmelt using unstructured triangular meshes

Albedo over rough snow and ice surfaces

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