The effects of sampling resolution on the surface albedos of dominant land cover types in the North American boreal region

Davidson, Andrew; Wang, Shusen

doi:10.1016/j.rse.2004.07.005

Cited by 46 publications

(28 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Resultsmentioning

confidence: 99%

“…They found that the broadband albedo of the snow covered forest increases as the latitude increases, and emphasized the role of canopy masking on the effective albedo in coniferous forests. Additionally, Davidson et al (2004) studied the effect of sampling resolution on broadband surface albedo in Canadian boreal forest using bith in-situ pyranometer and GOES-8 satellite data. They found a clear correlation between the land-cover type and clear-sky albedo of the seasonally snow covered boreal forest.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effective UV surface albedo of seasonally snow-covered lands

Tanskanen

Manninen

2007

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. At ultraviolet wavelengths the albedo of most natural surfaces is small with the striking exception of snow and ice. Therefore, snow cover is a major challenge for various applications based on radiative transfer modelling. The aim of this work was to determine the characteristic effective UV range surface albedo of various land cover types when covered by snow. First we selected 1 by 1 degree sample regions that met three criteria: the sample region contained dominantly subpixels of only one land cover type according to the 8 km global land cover classification product from the University of Maryland; the average slope of the sample region was less than 2 degrees according to the USGS's HYDRO1K slope data; the sample region had snow cover in March according to the NSIDC Northern Hemisphere weekly snow cover data. Next we generated 1 by 1 degree gridded 360 nm surface albedo data from the Nimbus-7 TOMS Lambertian equivalent reflectivity data, and used them to construct characteristic effective surface albedo distributions for each land cover type. The resulting distributions showed that each land cover type experiences a characteristic range of surface albedo values when covered by snow. The result is explained by the vegetation that extends upward beyond the snow cover and masks the bright snow covered surface.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effective UV surface albedo of seasonally snow-covered lands

Tanskanen

Manninen

2007

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…We simulate the albedo for a forest stand of a size of 1 ha, whereas the footprint of the site observations range from a few square metres (UAVSpec (Unmanned Aerial Vehicle Spectrometer system)) to 1200 m 2 (albedometer). Local measurements of sparse needleleaf forests underestimated the shortwave albedo considerably, in the case of snow on the ground by up to 0.3 (Davidson and Wang, 2004). This is due to the spatial heterogeneity inherent in point-topixel inter-comparison (Cescatti et al, 2012;Román et al, 2009).…”

Section: Tendency To Overestimate Near-infrared Albedo Of Needleleaf mentioning

confidence: 97%

“…The albedo of sparse needleleaf forest seems to be challenging, not only to model (Kuusk et al, 2010) but also to observe (Davidson and Wang, 2004). The Forest Radiative Transfer model (FRT) overestimated the reflectance spectra for EE-Jär in the near-infrared domain by up to 0.04 (Kuusk et al, 2010).…”

Section: Tendency To Overestimate Near-infrared Albedo Of Needleleaf mentioning

confidence: 99%

Forest summer albedo is sensitive to species and thinning: how should we account for this in Earth system models?

et al. 2014

View full text Add to dashboard Cite

Abstract. Although forest management is one of the instruments proposed to mitigate climate change, the relationship between forest management and canopy albedo has been ignored so far by climate models. Here we develop an approach that could be implemented in Earth system models. A stand-level forest gap model is combined with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning on summertime canopy albedo. This approach reveals which parameter has the largest affect on summer canopy albedo: we examined the effects of three forest species (pine, beech, oak) and four thinning strategies with a constant forest floor albedo (light to intense thinning regimes) and five different solar zenith angles at five different sites (40During stand establishment, summertime canopy albedo is driven by tree species. In the later stages of stand development, the effect of tree species on summertime canopy albedo decreases in favour of an increasing influence of forest thinning. These trends continue until the end of the rotation, where thinning explains up to 50 % of the variance in near-infrared albedo and up to 70 % of the variance in visible canopy albedo.The absolute summertime canopy albedo of all species ranges from 0.03 to 0.06 (visible) and 0.20 to 0.28 (nearinfrared); thus the albedo needs to be parameterised at species level. In addition, Earth system models need to account for forest management in such a way that structural changes in the canopy are described by changes in leaf area index and crown volume (maximum change of 0.02 visible and 0.05 near-infrared albedo) and that the expression of albedo depends on the solar zenith angle (maximum change of 0.02 visible and 0.05 near-infrared albedo). Earth system models taking into account these parameters would not only be able to examine the spatial effects of forest management but also the total effects of forest management on climate.

show abstract

“…This distinction is important since green canopies absorb most of the solar radiation in the VIS waveband for photosynthesis but reflect and transmit most of the radiation in the NIR waveband (Bonan, 2008). Leaf structural and physical properties can also influence withincanopy shadowing, which allows higher exposure of the underlying soil and/or snow cover, especially in low-density forests (Davidson and Wang, 2004). Leaf orientation influences albedo since the maximum incident solar radiation on a leaf occurs when the beam is perpendicular to the surface (Bonan, 2008).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Implementation of a soil albedo scheme in the CABLEv1.4b land surface model and evaluation against MODIS estimates over Australia

et al. 2014

View full text Add to dashboard Cite

Abstract. Land surface albedo, the fraction of incoming solar radiation reflected by the land surface, is a key component of the Earth system. This study evaluates snow-free surface albedo simulations by the Community Atmosphere Biosphere Land Exchange (CABLEv1.4b) model with the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Satellite Pour L'Observation de la Terre (SPOT) albedo. We compare results from offline simulations over the Australian continent. The control simulation has prescribed background snow-free and vegetation-free soil albedo derived from MODIS whilst the experiments use a simple parameterisation based on soil moisture and colour, originally from the Biosphere Atmosphere Transfer Scheme (BATS), and adopted in the Common Land Model (CLM). The control simulation, with prescribed soil albedo, shows that CABLE simulates overall albedo over Australia reasonably well, with differences compared to MODIS and SPOT albedos within ±0.1. Application of the original BATS scheme, which uses an eight-class soil classification, resulted in large differences of up to −0.25 for the near-infrared (NIR) albedo over large parts of the desert regions of central Australia. The use of a recalibrated 20-class soil colour classification from the CLM, which includes a higher range for saturated and VIS (visible) and NIR soil albedos, reduced the underestimation of the NIR albedo. However, this soil colour mapping is tuned to CLM soil moisture, a quantity which is not necessarily transferrable between land surface models. We therefore recalibrated the soil color map using CABLE's climatological soil moisture, which further reduced the underestimation of the NIR albedo to within ±0.15 over most of the continent as compared to MODIS and SPOT albedos. Small areas of larger differences of up to −0.25 remained within the central arid parts of the continent during summer; however, the spatial extent of these large differences is substantially reduced as compared to the simulation using the default eight-class uncalibrated soil colour map. It is now possible to use CABLE coupled to atmospheric models to investigate soil-moisture-albedo feedbacks, an important enhancement of the model.

show abstract

The effects of sampling resolution on the surface albedos of dominant land cover types in the North American boreal region

Cited by 46 publications

References 36 publications

Effective UV surface albedo of seasonally snow-covered lands

Effective UV surface albedo of seasonally snow-covered lands

Forest summer albedo is sensitive to species and thinning: how should we account for this in Earth system models?

Implementation of a soil albedo scheme in the CABLEv1.4b land surface model and evaluation against MODIS estimates over Australia

Contact Info

Product

Resources

About