SGP97 Upper Air: DOE ARM 915 MHz Profiler Winds

The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) 915 MHz Radar Wind Profiler and RASS Data Set is one of the various boundary layer data sets developed for the SGP97 project. This data set contains hourly average profiles of wind speed and direction, u and v wind components (from the Radar Wind Profiler), and virtual temperature (from the RASS [Radio Acoustic Sounding System]). The wind profiles have a vertical resolution of ~60 meters (m) in the low mode and ~200 m in the high mode. The RASS has a vertical resolution of ~100 m. The site is located at the DOE ARM SGP Central Facility near Lamont, Oklahoma. The radar wind profiler/RASS (RWP) measures wind profiles from (nominally) .1 km to 5 km and virtual temperature profiles from .1 km to 1.5 km. It operates by transmitting electromagnetic energy into the atmosphere and measuring the strength and frequency of backscattered energy. Virtual temperatures are recovered by transmitting an acoustic signal vertically and measuring the electromagnetic energy scattered from the acoustic wavefront. The propagation speed of the acoustic wave is proportional to the square root of the virtual temperature. The Primary quantities measured with the system are the intensity and Doppler frequency of backscattered radiation. The wind speed is determined from the Doppler frequency of energy scattered from refractive index fluctuations (caused primarily by moisture fluctuations but also by temperature fluctuations) embedded within the atmosphere; the virtual temperature is determined from the Doppler frequency of microwave energy scattered from acoustic energy propagating through the atmosphere. The 915 MHz radar wind profiler is manufactured by Radian Corp. It consists of a single-phased microstrip antenna array consisting of nine "panels" (most system have only four panels). The antenna is approximately 4 m square and is oriented in a horizontal plane so the "in-phase" beam travels vertically. Other components in the system include four stationary acoustic sources located at the corners of the antenna, a mobile acoustic source, a receiver, an interface module, and a computer for data analysis and processing. No flags are applied during data ingest of the consensus averaged winds and virtual temperatures. However, a parallel data stream with the ".b2" name field has data flags applied that look at relative values of temps or wind components. Neighboring values in space (height) and time (sequential profiles) are compared with predefined limits (given in the metadata of the NETCDF file). In addition to the unchanged wind component and temperature fields, a field of flags (on or off [1 or 0]) is supplied to "point" at suspect values. These data are in their original NetCDF format. No additional quality control was performed by the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS).

• Resource Title: GeoData catalog record.

  File Name: Web Page, url: https://geodata.nal.usda.gov/geonetwork/srv/eng/catalog.search#/metadata/e15ad525-a70f-47b0-982e-53eaf2e6ab8a