**5. Conclusions**

Aerodynamic roughness length within our study has shown variation spatially and temporally for a shallow accumulating snow environment. This was apparent in our results that showed differences in *z*0 mean values of about 14 × 10−<sup>3</sup> m between the plowed and unplowed field. Thus, single-point measurements of anemometric data may not account for *z*0 over a range of spatial and temporal scales. Geometrically calculated *z*0 using the Lettau method has shown to be an effective and more robust form of *z*0 estimation compared to the anemometric method and also producing similar, estimated values. The anemometric, single-point measurements will also not account for the snow-covered area, which changes based on its inverse relation with *z*0. However, SCA can be observed and estimated from satellite imagery or airborne lidar systems to create a more accurate estimation of *z*0.

**Author Contributions:** The experiments were designed by D.J.K., S.R.F., and W.L.B.; D.J.K. collected the field data; D.J.K. and S.R.F. did the analysis; W.L.B. helped with instrumentation setup; I.O. prepared the code to compute the geometric roughness length; J.E.S. and S.R.F. wrote the paper with input from G.A.S.; S.R.F. created the figures.

**Funding:** This research has been partially supported by the National Science Foundation under Grant No. DMS-1615909.

**Acknowledgments:** We thank the Colorado State University Water Center and the Colorado Water Institute for their financial support, especially for the installation of the anemometric tower. The Warner College of Natural Resources provided the Faro Terrestrial Lidar Scanner. Thanks are due to Dr. Edgar Andreas who provided some very insightful discussions about the movement of air over snow. We thank the referees for their useful comments that helped to improve the presentation of the paper. Partial funding for SRF was provided by the National Science Foundation project *"Pattern Formation and Spatiotemporal Complex Dynamics in Extended Anisotropic Systems"* (PI Iuliana Oprea; award number DMS-1615909). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. All data are available at Colorado State University by request to the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.
