Charts showing seasonal cycles of events caused by precipitation on snow
The seasonal cycles of events caused by precipitation on snow: accumulation (light + and heavy ++) or snowmelt (light - and heavy --). Subplot (a) summarizes their relative frequencies across the entire region without identifying what type of precipitation event caused them. The bottom plots illustrate these cycles for events caused by atmospheric rivers (b) or due to other phenomena (c). Atmospheric rivers cause a relatively higher proportion of light and heavy snowmelt events, contributing to the occurrence of up to 10-20 per cent of intense events in the region. Credit: Chen et al. [2019], Figure 5
Source: Geophysical Research Letters

Changing climate poses multiple questions concerning the future fate of snowpack, its contribution to runoff and extreme flooding, and seasonal distribution of water resource. Chen et al. [2019] scrutinize historic interactions of precipitation with snowpack in the western United States, specifically exploring how they affect regional runoff generation.

Atmospheric rivers, rare events of strong atmospheric water vapor transport into the coastal areas, are discovered to be important contributors to snowmelt events and significant runoff events and flooding in the Pacific Northwest. As atmospheric rivers are projected to change in the future, this study contributes to the understanding of their potential role in a warmer climate and the likely impacts on water resources and flooding in the western United States.

Citation: Chen, X., Duan, Z., Leung, L. R., & Wigmosta, M. [2019]. A framework to delineate precipitation‐runoff regimes: Precipitation versus Snowpack in the Western United States. Geophysical Research Letters, 46.

—Valeriy Ivanov, Editor, Geophysical Research Letters

Text © 2019. The authors. CC BY-NC-ND 3.0
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