A Framework to Delineate Precipitation‐Runoff Regimes: Precipitation Versus Snowpack in the Western United States

Journal Article · 28 November 2019 · Geophysical Research Letters

DOI: https://doi.org/10.1029/2019GL085184 · OSTI ID:1576065

Chen, Xiaodong  ^[1]; Duan, Zhuoran  ^[2]; Leung, L. Ruby  ^[1]; Wigmosta, Mark  ^[3]

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1. Atmospheric Sciences and Global Change Division Pacific Northwest National Laboratory Richland WA USA
2. Energy and Environment Directorate Pacific Northwest National Laboratory Richland WA USA, Department of Civil and Environmental Engineering University of Washington Seattle WA USA
3. Energy and Environment Directorate Pacific Northwest National Laboratory Richland WA USA

Abstract Snowpack accumulation/ablation affects the runoff response to precipitation by modulating the water flux reaching the surface. Previous studies mostly focused on “rain‐on‐snow” events. Here we propose a framework to extend the scope and classify precipitation events accompanied by snow accumulation/ablation (precipitation‐and‐snow, or PAS, events) into five regimes. This framework is applied to a regional climate simulation over the western United States for 1981–2015 to reveal regions where daily changes in snowpack alter the surface hydrologic responses to precipitation. Over the western United States, PAS events account for 50–90% of all the precipitation events. Compared to the broad spatial distribution of snow accumulation‐type PAS events, snowmelting‐type PAS events are limited to coastal high‐elevation areas. Atmospheric rivers, a key driver of heavy precipitation in the region, account for only 2% of the PAS events, but they trigger significant snowmelt, accounting for 20% and 11% of light and heavy snowmelting events, respectively.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC06-76RL01830
• OSTI ID: 1576065
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 22 Vol. 46; ISSN 0094-8276
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English