This study investigates the extent of the rain‐snow transition zone across the complex terrain of the western United States for both late 20th century climate and projected changes in climate by the mid‐21st century. Observed and projected temperature and precipitation data at 4 km resolution were used with an empirical probabilistic precipitation phase model to estimate and map the likelihood of snow versus rain occurrence. This approach identifies areas most likely to undergo precipitation phase change over the next half century. At broad scales, these projections indicate an average 30% decrease in areal extent of winter wet‐day temperatures conducive to snowfall over the western United States. At higher resolution scales, this approach identifies existing and potential experimental sites best suited for research investigating the mechanisms linking precipitation phase change to a broad array of processes, such as shifts in rain‐on‐snow flood risk, timing of water resource availability, and ecosystem dynamics.

The phase of precipitation when it reaches the ground is a first-order driver of hydrologic processes in a watershed. The presence of snow, rain, or mixed-phase precipitation affects the initial and boundary conditions that drive hydrological models. Despite their foundational importance to terrestrial hydrology, typical phase partitioning methods (PPMs) specify the phase based on near-surface air temperature only. Our review conveys the diversity of tools available for PPMs in hydrological modeling and the advancements needed to improve predictions in complex terrain with large spatiotemporal variations in precipitation phase. Initially, we review the processes and physics that control precipitation phase as relevant to hydrologists, focusing on the importance of processes occurring aloft. There is a wide range of options for field observations of precipitation phase, but there is a lack of a robust observation networks in complex terrain. New remote sensing observations have the potential to increase PPM fidelity, but generally require assumptions typical of other PPMs and field validation before they are operational. We review common PPMs and find that accuracy is generally increased at finer measurement intervals and by including humidity information. One important tool for PPM development is atmospheric modeling, which includes microphysical schemes that have not been effectively linked to hydrological models or validated against near-surface precipitation-phase observations. The review concludes by describing key research gaps and recommendations to improve PPMs, including better incorporation of atmospheric information, improved validation datasets, and regional-scale gridded data products. Two key points emerge from this synthesis for the hydrologic community: (1) current PPMs are too simple to capture important processes and are not well validated for most locations, (2) lack of sophisticated PPMs increases the uncertainty in estimation of hydrological sensitivity to changes in precipitation phase at local to regional scales. The advancement of PPMs is a critical research frontier in hydrology that requires scientific cooperation between hydrological and atmospheric modelers and field scientists.

Kemp, K. B., J. J. Blades, P. Z. Klos, T. E. Hall, J. E. Force, P. Morgan, and W. T. Tinkham. 2015. Managing for climate change on federal lands of the western United States: perceived usefulness of climate science, effectiveness of adaptation strategies, and barriers to implementation. Ecology and Society 20(2): 17.http://dx.doi.org/10.5751/ES-07522-200217

Ecosystem-service production is strongly influenced by the landscape configuration of natural and human systems. Ecosystem services are not only prod

Interdisciplinarity is crucial for addressing the complex problems society faces. We present a model for educating doctoral students for careers involving interdisciplinary, team-based research to address problem-focused questions. The educational model is theoretically based and evaluated in light of the literature, faculty perspectives, and an assessment by students of educational successes and challenges they experienced. The educational model involves (a) the identification of integrated research questions combining team members’ disciplines, (b) course work to review theoretical underpinnings of interdisciplinarity and to develop integrated research proposals to address the questions, (c) meetings and workshops to enhance team cohesiveness, (d) engagement with stakeholders, and (e) interdisciplinary team research that yields joint dissertation chapters and publications. The model achieved a high level of integration among students. This model addresses the widely acknowledged need to impart interdisciplinary research and team membership skills as part of graduate education.