An improved downward longwave clear-sky radiative flux (LWd) parameterization was developed and evaluated with field measurements collected in two projects: the Collaborative Interdisciplinary Cryospheric Experiment in 2000 and the Canadian Arctic Shelf Exchange Study. The 722 operational upper air soundings collected in Resolute Bay in 2000 were used to develop this scheme. After comparing this new method with 11 previous schemes we conclude that our new scheme has the smallest mean bias error: -0.8 Wm-2 and -0.7 Wm-2 in two projects, while all of the schemes have similar correlation coefficients: 0.96 and 0.91. Our new method has a varying root-mean square error, depending on the seasonal background of sampling period; it decreases with the extension of the sampling period and the inclusion of multiple sampling seasons.