Data Description

Wind measurements used in the gap-filling model were collected at six USGS meteorological sites—MDL, MDN, BLB, HDB, SSHR, WMR—as well as two nearby AgriMet sites (Bureau of Reclamation, 1997)—AGKO and KFLO (fig. 1). Meteorological instrumentation at sites MDL and MDN was mounted on floating rafts on the lake during the summer (approximately May through September); data were collected at the other sites continuously through the year. Construction associated with the breaching of levees around the Williamson River Delta dictated that the site near the mouth of the Williamson River be relocated twice during the period covered by this report. Site WMR was relocated to WME in May 2007, and WME was in turn relocated to WRW in April 2008. Data from WMR, WME, and WRW were used interchangeably in this report due to their close proximity; references to WMR wind data should be interpreted to mean data from the Williamson River Delta site, which was at one of these three locations, depending on the time period. During the periods used for calibration and validation of the gap-filling model, USGS data were measured at 10-minute intervals. AgriMet data were collected at 15-minute intervals, and for the purposes of the gap-filling wind model, were interpolated linearly (after a conversion to north-south and east-west components) to match the 10-minute intervals of the USGS data. The air temperature used in the gap-filling model was measured at site WMR and was collected at 10-minute intervals.

Datasets used in the historical wind model included the wind measured at the AgriMet sites AGKO and KFLO (daily mean speed and direction), as well as global solar radiation (cumulative daily), relative humidity (daily mean), and air temperature (daily mean) measured at AGKO. These variables were downloaded from the AgriMet website as daily values (Bureau of Reclamation, 1997). The daily mean wind speed and direction was then converted to east-west and north-south components, when appropriate, and depending on the model type. An additional dataset used in the historical model is the data collected since 1959 at the Klamath Falls Airport (KLMT) by the National Oceanic and Atmospheric Administration and distributed via the Internet by the NCDC (National Oceanic and Atmospheric Administration, no date). The KLMT site (fig. 1) is only about 2 km from the KFLO site, but the sensors at the AgriMet sites are at 2 m above the ground, whereas the sensors at the KLMT sites are at 10 m above the ground. Daily means of the wind components, air temperature, dew point temperature, sky cover, and altimetric pressure were calculated from the original NCDC data, which were collected at irregular intervals over the day, but generally at hourly temporal resolution. Daily means of sky cover were calculated after converting categorical values to numerical values as follows (adapted from ASOS user’s guide [National Weather Service, 1998]): clear sky = 0, scattered clouds = 0.31, broken clouds = 0.75, overcast sky = 0.83, partial obscuration = 0.92, and obscuration = 1.0.

First posted October 27, 2010