Radiation data corrections for snow‐covered sensors: are they needed for snowmelt modelling?

Abstract

AbstractUp‐looking solar and atmospheric radiation sensors at remote and quasi‐remote weather stations are typically intermittently covered by snow in the winter. Numerous years of radiation data compromised in this way have been collected and archived at the Snow Research Station (SRS) in Danville, Vermont, and undoubtedly at numerous other research stations around the globe. Potential users of these archived data must question whether the data have value for their purpose, whether they can be corrected, what methods can be used to correct them, and perhaps most importantly, will time‐consuming correction efforts be justified by improved model performance. To answer these questions, both simple and elaborate methods of correcting incident solar and atmospheric radiation data were developed and applied to the 2001 snow season radiation data collected at the SRS. Snow‐affected incident solar radiation was estimated with reflected solar radiation measurements and either a simple albedo assumption or an albedo model. The equations of Idso, Brutsaert, Brunt, and Anderson and Baker were considered for correcting atmospheric radiation. The technique of Anderson and Baker was a good practical choice for this site, when used with a station offset, clearness index, and clear‐sky radiation model. Energy balance snowmelt calculations were made with SNTHERM, an internationally known and publicly available physically based snow process model. There was little justification for more than minimal corrections to radiation measurements for the presence of snow on radiation sensors when modelling snow depth, water equivalent, or melt efflux, because errors caused by snow‐covered solar and atmospheric radiation sensors largely offset one another. More elaborate efforts to correct both solar and atmospheric radiation data would be justified when correct quantification of individual snowpack energy components is important. Copyright © 2004 John Wiley & Sons, Ltd.