<p><strong>Abstract.</strong> Brightness temperature (<i>T</i>_b) data from the Special Sensor Microwave Imager (SSM/I) 37 V-GHz frequency provides a time series from 1988 to 2010 that enables the assessment of snowmelt timing trends (onset, end of melt-refreeze, and duration) for the Yukon River Basin. <i>T</i>_b and diurnal amplitude variation (DAV) thresholds determine dates of melt onset and melt-freeze end (end of high DAV), defined as the first date when thresholds are

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... met for more than three of five consecutive days. Temporal and spatial trends in melt onset and end of melt-refreeze date are determined with varying time period intervals and for each sub-basin and elevation class. Earlier melt onset trends are found in the highest elevations and northernmost sub-basins (Porcupine, Chandalar, and Koyukuk Rivers). Significant later (>0.75 d yr⁻¹) end of melt-refreeze and longer melt duration trends are found in a majority of the sub-basins. Moving interval trends suggest interannual variability within the time series and a power spectrum analysis reveals peak frequencies and periods of 5–7 and ~11 years, possibly related to El Nino- Southern Oscillation and the solar cycle, respectively. Latitude and elevation display the dominant controls on timing variance and spring solar flux is highly correlated with melt timing in middle elevations.</p>