A Decade of Surface Solar Radiation Deposition Across the Pacific Northwest

Abstract:

The University of Oregon Solar Radiation Monitoring Laboratory maintains monitoring sites throughout the Pacific Northwest, from which we obtained continuous, 5-minute frequency time series data for the 10 year period between 2004 and 2013. We chose to analyze five sites within the Pacific Northwest (three in Oregon and one each in Idaho and Montana). The sites range in climate from wet lowland coastal to semi-arid high plains to intermountain valley, and elevations from 150 to 1500 m. Analysis of the time series yielded descriptive statistics of solar energy deposition on daily, seasonal and annual timescales for each site. Estimates of the contributions of clear and cloudy skies to the solar deposition have been obtained using the Long-Ackerman (JGR, 2000) technique. We are currently creating comparisons on varying timescales between measured surface solar energy deposition at these five sites and estimates from satellite data. In this presentation, we will describe the results of our analysis, focusing both on the variability at each site and comparisons among the five sites. To our knowledge, this level of detail has not previously been reported across the highly variable terrain of the Pacific Northwest region. While a 10-year period is inadequate for trend analysis, it does provide considerable insight into interannual variability on daily to seasonal timescales. In addition, we will present comparisons between satellite estimates and surface solar deposition measurements. Given the on-going need to use satellite estimates as a proxy for actual ground-based measurements, these assessments are critically important to understand the reliability of the satellite estimates on a variety of timescales and differing regional surface types.