<?xml version="1.0" encoding="UTF-8"?>
<metadata>
  <idinfo>
    <citation>
      <citeinfo>
        <origin>PRISM Group at Oregon State University</origin>
        <pubdate>20260310</pubdate>
        <title>United States Daily Total Global Shortwave Irradiance on a Sloped Ground Surface, January 25, 1993 (800m; COG)</title>
        <geoform>raster digital data</geoform>
        <pubinfo>
          <pubplace>Corvallis, OR, USA</pubplace>
          <publish>PRISM Group at Oregon State University</publish>
        </pubinfo>
        <onlink>https://data.prism.oregonstate.edu</onlink>
      </citeinfo>
    </citation>
    <descript>
      <abstract>Daily dataset covering the conterminous U.S., for January 25, 1993. Contains spatially gridded daily total global shortwave irradiance on a sloped ground surface at 800m grid cell resolution. Point measurements and estimates of global (diffuse + direct) downward solar (short-wave) irradiance on a horizontal plane at the ground surface were converted to an effective cloud transmittance by dividing by the solar clear sky irradiance. Clear-sky irradiance at the ground surface was modeled at a 30-arc-sec grid spacing with the Image Processing Workbench (IPW) using MERRA-2 reanalysis data to derive atmospheric parameters.  Distribution of effective cloud transmittance point measurements and estimates to the spatial grid was accomplished using the PRISM model. Total irradiance on horizontal and sloped ground surfaces was modeled with IPW, using the cloud transmittance grids as inputs. Terrain data was derived from a 30-arc-sec version of the US National Elevation Database. Modeled values incorporate the effects of elevation, shading, and reflection from nearby terrain on irradiance.</abstract>
      <purpose>Display and/or analysis requiring spatially distributed daily global shortwave irradiance on a sloped ground surface for January 25, 1993.</purpose>
      <supplinf>There are many methods of interpolating weather from monitoring stations to grid points. Some provide estimates of acceptable accuracy in flat terrain, but few have been able to adequately explain the extreme, complex variations that occur in mountainous regions. Significant progress in this area has been achieved through the development of PRISM (Parameter-elevation Regressions on Independent Slopes Model). PRISM is an analytical model that uses point data and an underlying grid such as a digital elevation model (DEM) or a 30 year average to generate gridded estimates of daily, monthly, or annual precipitation and temperature (as well as other parameters). PRISM is well suited to regions with mountainous terrain, because it incorporates a conceptual framework that addresses the spatial scale and pattern of orographic processes. Grids were modeled on a daily or monthly basis. Annual grids were produced by averaging (temperature, vapor pressure, vapor pressure deficit, and solar radiation) or summing (precipitation) the monthly grids. A day is defined as 1200 UTC-1200 UTC and labeled as the ending day (e.g., 5 January covers the period 1200 UTC 4 January - 1200 UTC 5 January). Because station data latency times can be several weeks or months, multiple versions of a grid are produced until most data have arrived and have been QC'ed and edited by both the originator's and in-house processes.  A total of eight versions of a daily grid are released over a six-month period:  A first version the following day (D+1), a second version four days later (D+5), and successive versions at approximately the middle of the following six months.  Monthly grid versions follow the same progression, except no D+5 version, for a total of seven. Further details on this dataset are available here: https://prism.oregonstate.edu/documents/PRISM_datasets.pdf.
      </supplinf>
    </descript>
    <timeperd>
      <timeinfo>
        <rngdates>
          <begdate>19930125</begdate>
          <enddate>19930125</enddate>
        </rngdates>
      </timeinfo>
      <current>observed</current>
    </timeperd>
    <status>
      <progress>complete</progress>
      <update>as needed</update>
    </status>
    <spdom>
      <bounding>
        <westbc>-125.0208333</westbc>
        <eastbc>-66.4791667</eastbc>
        <northbc>49.9375000</northbc>
        <southbc>24.0625000</southbc>
      </bounding>
    </spdom>
    <keywords>
      <theme>
        <themekt>PRISM Group</themekt>
        <themekey>global shortwave irradiance on a sloped ground surface</themekey>
      </theme>
      <place>
        <placekt>US Census Bureau</placekt>
        <placekey>Conterminous US</placekey>
      </place>
    </keywords>
    <accconst>Access pursuant to license agreement</accconst>
    <useconst>Acknowledgement of the following agencies in products derived from these data: PRISM Group at Oregon State University.</useconst>
  </idinfo>
  <dataqual>
    <attracc>
      <attraccr>Similar quality assurance procedures were used with all input data sets.</attraccr>
    </attracc>
    <logic>Point estimates originated from many federal, state, and local weather networks. A list of networks is available from https://www.prism.oregonstate.edu/documents/PRISM_datasets.pdf. All station data were subjected to quality control checks by the PRISM Group at Oregon State University.</logic>
    <complete>This dataset is considered complete. Please view the logic section of this document for further information.</complete>
    <posacc>
      <horizpa>
        <horizpar>Accuracy of this data set is based on the original specification of the Defense Mapping Agency (DMA) 1 degree digital elevation models (DEM). The stated accuracy of the original DEMs are 130 m circular error with 90% probability.</horizpar>
      </horizpa>
    </posacc>
    <lineage>
      <srcinfo>
        <srccite>
          <citeinfo>
            <origin>PRISM Group</origin>
            <pubdate>20260310</pubdate>
            <title>United States Daily Total Global Shortwave Irradiance on a Sloped Ground Surface, January 25, 1993 (800m; COG)</title>
          </citeinfo>
        </srccite>
        <typesrc>digital file</typesrc>
        <srctime>
          <timeinfo>
            <rngdates>
              <begdate>19930125</begdate>
              <enddate>19930125</enddate>
            </rngdates>
          </timeinfo>
          <srccurr>publication date</srccurr>
        </srctime>
        <srccitea>solslope_19930125</srccitea>
        <srccontr>CONUS 800m global shortwave irradiance on a sloped ground surface data representing 19930125</srccontr>
      </srcinfo>
      <procstep>
        <procdesc>Daily global shortwave irradiance on a sloped ground surface grid processing</procdesc>
        <procdate>20251120</procdate>
        <proctime>1517</proctime>
      </procstep>
      <procstep>
        <procdesc>Daily global shortwave irradiance on a sloped ground surface grid processing</procdesc>
        <procdate>20260121</procdate>
        <proctime>1456</proctime>
      </procstep>
      <procstep>
        <procdesc>Daily global shortwave irradiance on a sloped ground surface grid processing</procdesc>
        <procdate>20260126</procdate>
        <proctime>2215</proctime>
      </procstep>
    </lineage>
  </dataqual>
  <spdoinfo>
    <direct>Raster</direct>
    <rastinfo>
      <rasttype>Grid Cell</rasttype>
    </rastinfo>
  </spdoinfo>
  <spref>
    <horizsys>
      <geograph>
        <latres>0.00833333</latres>
        <longres>0.00833333</longres>
        <geogunit>Decimal degrees</geogunit>
      </geograph>
      <geodetic>
        <horizdn>North American Datum of 1983</horizdn>
        <ellips>Geodetic Reference System 80</ellips>
        <semiaxis>6378137</semiaxis>
        <denflat>298.257</denflat>
      </geodetic>
    </horizsys>
  </spref>
  <eainfo>
    <detailed>
      <enttyp>
        <enttypl>Raster data representing meteorological variables</enttypl>
        <enttypd>Spatially gridded values</enttypd>
        <enttypds>
          [1] Daly, C., Halbleib, M., Smith, J.I., Gibson, W.P., Doggett, M.K., Taylor, G.H., Curtis, J., and Pasteris, P.A. 2008. Physiographically-sensitive mapping of temperature and precipitation across the conterminous United States. International Journal of Climatology, 28: 2031-2064. doi:10.1002/joc.1688
          [2] Daly, C., J.I. Smith, and K.V. Olson. 2015. Mapping atmospheric moisture climatologies across the conterminous United States. PloS ONE 10(10):e0141140. doi:10.1371/journal.pone.0141140
          [3] Daly, C., M.K. Doggett, J.I. Smith, K.V. Olson, M.D. Halbleib, Z. Dimcovic, D. Keon, R.A. Loiselle, B. Steinberg, A.D. Ryan, C.M. Pancake, and E.M. Kaspar. 2021. Challenges in observation-based mapping of daily precipitation across the conterminous United States. Journal of Atmospheric and Oceanic Technology 38(11): 1979-1992. doi:10.1175/JTECH-D-21-0054.1
          [4] Rupp, D.E., C. Daly, M.K. Doggett, J.I. Smith, and B. Steinberg. 2022. Mapping an observation-based global solar irradiance climatology across the conterminous United States. Journal of Applied Meteorology and Climatology 61(7): 857-876. doi:10.1175/JAMC-D-21-0236.1
        </enttypds>
      </enttyp>
      <attr>
        <attrlabl>Daily total global shortwave irradiance on a sloped ground surface (COG format)</attrlabl>
        <attrdef>Spatially gridded daily total global shortwave irradiance on a sloped ground surface values</attrdef>
        <attrdefs>PRISM Group</attrdefs>
        <attrdomv>
          <rdom>
            <rdommin>0.12</rdommin>
            <rdommax>22.60</rdommax>
            <attrunit>MJm-2day-1</attrunit>
          </rdom>
        </attrdomv>
      </attr>
    </detailed>
  </eainfo>
  <distinfo>
    <distrib>
      <cntinfo>
        <cntperp>
          <cntper>Matthew Doggett</cntper>
          <cntorg>PRISM Group</cntorg>
        </cntperp>
        <cntaddr>
          <addrtype>mailing and physical</addrtype>
          <address>NACSE, University Plaza</address>
          <address>1600 SW Western Blvd, Ste 198</address>
          <address>Oregon State University</address>
          <city>Corvallis</city>
          <state>OR</state>
          <postal>97333</postal>
          <country>USA</country>
        </cntaddr>
        <cntvoice>(541) 737-2531</cntvoice>
        <cntemail>prism_orders@nacse.org</cntemail>
      </cntinfo>
    </distrib>
    <distliab>none</distliab>
  </distinfo>
  <metainfo>
    <metd>20260306</metd>
    <metc>
      <cntinfo>
        <cntperp>
          <cntper>Matthew Doggett</cntper>
          <cntorg>PRISM Group</cntorg>
        </cntperp>
        <cntaddr>
          <addrtype>mailing and physical</addrtype>
          <address>NACSE, University Plaza</address>
          <address>1600 SW Western Blvd, Ste 198</address>
          <address>Oregon State University</address>
          <city>Corvallis</city>
          <state>OR</state>
          <postal>97333</postal>
          <country>USA</country>
        </cntaddr>
        <cntvoice>(541) 737-2531</cntvoice>
        <cntemail>doggett@nacse.org</cntemail>
      </cntinfo>
    </metc>
    <metstdn>FDGC Content Standard for Digital Geospatial Metadata and Biological Data Profile</metstdn>
    <metstdv>FDGC-STD-001-1998</metstdv>
  </metainfo>
</metadata>
