Effective UV surface albedo of seasonally snow-covered lands

Tanskanen, A.; Manninen, Terhikki

doi:10.5194/acp-7-2759-2007

Cited by 26 publications

(20 citation statements)

References 30 publications

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“…The MTW method was applied to the TOMS 360 nm LER time-series during the period 1979-1992. At high latitudes the new climatology gave larger surface albedo than the MLER climatology, during the snow cover transition periods, where the MTW surface albedo is usually several percent larger than the climatological values (Tanskanen and Manninen, 2007). Higher surface albedo produces higher values of the surface UV estimates; thus, TOMS algorithm produces UV levels lower than OMI estimates over snow covered regions during transition periods.…”

Section: Toms and Omi Productsmentioning

confidence: 99%

Use of satellite erythemal UV products in analysing the global UV changes

et al. 2011

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Abstract. Long term changes in solar UV radiation affect global bio-geochemistry and climate. The satellite-based dataset of TOMS (Total Ozone Monitoring System) and OMI (Ozone Monitoring Instrument) of erythemal UV product was applied for the first time to estimate the long-term ultraviolet (UV) changes at the global scale. The analysis of the uncertainty related to the different input information is presented. OMI and GOME-2 (Global Ozone Monitoring Experiment-2) products were compared in order to analyse the differences in the global UV distribution and their effect on the linear trend estimation.The results showed that the differences in the inputs (mainly surface albedo and aerosol information) used in the retrieval, affect significantly the UV change calculation, pointing out the importance of using a consistent dataset when calculating long term UV changes. The areas where these differences played a major role were identified using global maps of monthly UV changes. Despite the uncertainties, significant positive UV changes (ranging from 0 to about 5 %/decade) were observed, with higher values in the Southern Hemisphere at mid-latitudes during springsummer, where the largest ozone decrease was observed.

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Section: Toms and Omi Productsmentioning

confidence: 99%

Use of satellite erythemal UV products in analysing the global UV changes

et al. 2011

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“…Moreover, surface UV albedo is an essential parameter for various applications based on radiative transfer (RT) modeling, including various satellite retrieval algorithms. For example, current satellite UV algorithms demand better information on UV albedo, especially for land when covered by snow (e.g., Arola et al, 2003, Tanskanen andManninen, 2007).…”

Section: Introductionmentioning

confidence: 99%

Diurnal variations in the UV albedo of arctic snow

et al. 2008

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Abstract. The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV) albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67 • 22 N, 26 • 39 E, 179 m a.s.l.) during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0 • C on the following mornings. Hence, the reversible diurnal change, evident for ∼1-2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

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“…For melting snow seasons these assumptions have to be very carefully implemented in various modeling codes. Also, during snowmelt, the effective surface UV albedo distributions (like those presented in Manninen, 2007, andRobinson andKukla, 1984) are expected to move toward smaller values. We may expect that snow height-dependent parameterizations (like in Arola et al, 2003), in turn, might function well during melt time.…”

Section: On the Importance Of Albedo Estimatesmentioning

confidence: 99%

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

et al. 2013

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Abstract. We have measured spectral albedo, as well as ancillary parameters, of seasonal European Arctic snow at Sodankylä, Finland (67°22' N, 26°39' E). The springtime intensive melt period was observed during the Snow Reflectance Transition Experiment (SNORTEX) in April 2009. The upwelling and downwelling spectral irradiance, measured at 290–550 nm with a double monochromator spectroradiometer, revealed albedo values of ~0.5–0.7 for the ultraviolet and visible range, both under clear sky and variable cloudiness. During the most intensive snowmelt period of four days, albedo decreased from 0.65 to 0.45 at 330 nm, and from 0.72 to 0.53 at 450 nm. In the literature, the UV and VIS albedo for clean snow are ~0.97–0.99, consistent with the extremely small absorption coefficient of ice in this spectral region. Our low albedo values were supported by two independent simultaneous broadband albedo measurements, and simulated albedo data. We explain the low albedo values to be due to (i) large snow grain sizes up to ~3 mm in diameter; (ii) meltwater surrounding the grains and increasing the effective grain size; (iii) absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon) in snow of 87 ppb, and organic carbon 2894 ppb, at the time of albedo measurements. The high concentrations of carbon, detected by the thermal–optical method, were due to air masses originating from the Kola Peninsula, Russia, where mining and refining industries are located.

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Effective UV surface albedo of seasonally snow-covered lands

Cited by 26 publications

References 30 publications

Use of satellite erythemal UV products in analysing the global UV changes

Use of satellite erythemal UV products in analysing the global UV changes

Diurnal variations in the UV albedo of arctic snow

Spectral albedo of seasonal snow during intensive melt period at Sodankylä, beyond the Arctic Circle

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