<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>David M. Wolock</dc:contributor>
  <dc:contributor>Melissa Valentin</dc:contributor>
  <dc:creator>Gregory J. McCabe</dc:creator>
  <dc:date>2018</dc:date>
  <dc:description>&lt;p&gt;Winter snowfall and accumulation is an important component of the surface water supply in the western United States. In these areas, increasing winter temperatures&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;associated with global warming can influence the amount of winter precipitation&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;that falls as snow&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;. In this study we examine long-term trends in the fraction of winter&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;that falls as&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;(Sfrac) for 175 hydrologic units (HUs) in snow-covered areas of the western United States for the period 1951–2014. Because&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is a substantial contributor to runoff&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;across most of the western United States, we also examine long-term trends in water-year runoff efficiency [computed as water-year&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;/water-year&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;(Reff)] for the same 175 HUs. In that most&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;records are short in length, we use model-simulated&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;from a monthly water balance model. Results for Sfrac indicate long-term negative trends for most of the 175 HUs, with negative trends for 139 (~79%) of the HUs being statistically significant at a 95% confidence level (&lt;i&gt;p&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 0.05). Additionally, results indicate that the long-term negative trends in Sfrac have been largely driven by increases in&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;. In contrast, time series of Reff for the 175 HUs indicate a mix of positive and negative long-term trends, with few trends being statistically significant (at&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;p&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 0.05). Although there has been a notable shift in the timing of&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;to earlier in the year for most HUs, there have not been substantial decreases in water-year&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;for the 175 HUs.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1175/JHM-D-17-0227.1</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Meteorological Society</dc:publisher>
  <dc:title>Warming is driving decreases in snow fractions while runoff efficiency remains mostly unchanged in snow-covered areas of the western United States</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>