Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts

Geometric effects induced by the underlying terrain slope or by tilt errors of the radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, artificial diurnal albedo variations in the order of 1–20 % are observed. The present paper proposes a general method t...

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Main Authors: U. Weiser, M. Olefs, W. Schöner, G. Weyss, B. Hynek
Format: Article
Language:English
Published: Copernicus Publications 2016-04-01
Series:The Cryosphere
Online Access:http://www.the-cryosphere.net/10/775/2016/tc-10-775-2016.pdf
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spelling doaj-cc3a86c5f199498fbb810df170ad06752020-11-24T23:42:33ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242016-04-0110277579010.5194/tc-10-775-2016Correction of broadband snow albedo measurements affected by unknown slope and sensor tiltsU. Weiser0M. Olefs1W. Schöner2G. Weyss3B. Hynek4Central Institute for Meteorology and Geodynamics (ZAMG), Vienna, AustriaCentral Institute for Meteorology and Geodynamics (ZAMG), Vienna, AustriaInstitute of Geography and Regional Research, University of Graz, Graz, AustriaCentral Institute for Meteorology and Geodynamics (ZAMG), Vienna, AustriaCentral Institute for Meteorology and Geodynamics (ZAMG), Vienna, AustriaGeometric effects induced by the underlying terrain slope or by tilt errors of the radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, artificial diurnal albedo variations in the order of 1–20 % are observed. The present paper proposes a general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known. We demonstrate that atmospheric parameters for this correction model can either be taken from a nearby well-maintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of sensors and the underlying terrain slope. This then allows us to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious over- or underestimations of albedo. It is also demonstrated that differences between measured and corrected albedo are generally highest for large solar zenith angles.http://www.the-cryosphere.net/10/775/2016/tc-10-775-2016.pdf
collection DOAJ
language English
format Article
sources DOAJ
author U. Weiser
M. Olefs
W. Schöner
G. Weyss
B. Hynek
spellingShingle U. Weiser
M. Olefs
W. Schöner
G. Weyss
B. Hynek
Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
The Cryosphere
author_facet U. Weiser
M. Olefs
W. Schöner
G. Weyss
B. Hynek
author_sort U. Weiser
title Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
title_short Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
title_full Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
title_fullStr Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
title_full_unstemmed Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
title_sort correction of broadband snow albedo measurements affected by unknown slope and sensor tilts
publisher Copernicus Publications
series The Cryosphere
issn 1994-0416
1994-0424
publishDate 2016-04-01
description Geometric effects induced by the underlying terrain slope or by tilt errors of the radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, artificial diurnal albedo variations in the order of 1–20 % are observed. The present paper proposes a general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known. We demonstrate that atmospheric parameters for this correction model can either be taken from a nearby well-maintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of sensors and the underlying terrain slope. This then allows us to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious over- or underestimations of albedo. It is also demonstrated that differences between measured and corrected albedo are generally highest for large solar zenith angles.
url http://www.the-cryosphere.net/10/775/2016/tc-10-775-2016.pdf
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