Andrew (Drew) Slater was an exemplary scientist whose research interests spanned a wide range of fields from land surface modelling, permafrost, snow, hydrology and data assimilation. He made significant impacts in all these fields. He was a complete scientist, combining theory, modelling and field work. He had a keen intellect and pursued excellence in his work, which he also expected from others. He was ready to provide thoughtful criticism at meetings and in the review process, always with the intent of getting others to “lift their game” and push science forward.
He cut his scientific teeth as a graduate student examining parameterizations of snow schemes in land models as part of the PILPS 2d project. His highly cited paper reporting this work [Slater et al, 2001] not only compared snow schemes used in land models but also identified causes of the differences between these schemes; notably how models represented sub-grid heterogeneity and effects of stability induced feedbacks on the longwave radiation balance. After completing his PhD in 2003, Drew shifted his attention to improving streamflow forecasting in snow-dominated basins. He published papers on ensemble data assimilation [Slater et al, 2006], a critical examination of snow reconstruction methods [Slater et al, 2013] and recently a compilation of solar radiation observations from mesoscale observing networks in the United States [Slater, 2016].
Drew is perhaps best known for his work on improving representation of Arctic land processes in models. In 2005, along with Dave Lawrence, Drew published a paper highlighting the projected degradation of near-surface permafrost [Lawrence and Slater, 2005]. While these projection were based on output from a model with good representation of frozen soil physics, it highlighted shortcomings in land models. Drew set about not only trying to improve land models but also to develop benchmarks to allow frozen soil processes in models to be compared [Slater and Lawrence 2013].
Drew pursued science as an endeavor rather than a career. Always curious, always searching for interesting problems to work on and always keen to communicate his work to everyone, from elementary school children to his colleagues. In the past few years he became interested in seasonal forecasting of sea ice. Using his knowledge of forecasting, data assimilation and statistics, he developed a simple but skillful sea ice prediction model that performed as well as, if not better than, the current crop of physically-based sea ice models. Keen to communicate this work to others, he developed web pages to not only present the results of this work to both the scientific community and general public, but also to explain the results and demonstrate the skill and uncertainty of the model. He also developed a popular set of web pages to provide near real-time snow depth for the western US. This pro-bono work was mostly driven by his passion for snow and skiing, as well as by a desire to provide information about the best-skiing to his fellow powder hounds.
His contributions to science and to communicating science are appreciated by colleagues and members of the general public.
Slater, A. G. 2016. Surface solar radiation in North America: A comparison of observations, reanalyses, satellite, and derived products. Journal of Hydrometeorology 17(1): 401-420. doi:10.1175/JHM-D-15-0087.1.
Slater, A. G., and D. Lawrence. 2013. Diagnosing present and future permafrost from climate models. Journal of Climate 26, 5,608-5,623. doi: doi:10.1175/JCLI-D-12-00341.1.
Slater A. G., A. P. Barrett, M. P. Clark, J. D. Lundquist, and M. S. Raleigh. 2013. Uncertainty in seasonal snow reconstruction: Relative impacts of forcing and image availability. Advances in Water Resources 55, 165-177, doi:10.1016/j.advwatres.2012.07.006.
Slater, A. G., and M. P. Clark. 2006. Snow data assimilation via an ensemble Kalman filter. Journal of Hydrometeorology, 7(3): 478-493. doi:10.1175/JHM505.1.
Slater, A., C. Schlosser, C. Desborough, A. Pitman, A. Henderson-Sellers, A. Robock, K. Vinnikov, J. Entin, K. Mitchell, F. Chen, A. Boone, P. Etchevers, F. Habets, J. Noilhan, H. Braden, P. Cox, P. de Rosnay, R. Dickinson, Z. Yang, Y. Dai, Q. Zeng, Q. Duan, V. Koren, S. Schaake, N. Gedney, Y. Gusev, O. Nasonova, J. Kim, E. Kowalczyk, A. Shmakin, T. Smirnova, D. Verseghy, P. Wetzel, and Y. Xue. 2001. The representation of snow in land-surface schemes; Results from PILPS 2(d). Journal of Hydrometeorology 2(1): 7-25. doi:10.1175/1525-7541(2001)002<0007:TROSIL>2.0.CO;2.
Memoriam written by Andrew Barrett, NSIDC