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NSF LOWER ATMOSPHERIC OBSERVING FACILITIES The majority of NSF's Lower Atmospheric Observing Facilities is managed, operated and maintained by NCAR/ATD. All platforms and instruments are available to the scientific research community.
	Ground-based Facilities GPS/Loran Atmospheric Sounding System Integrated Sounding System Integrated Surface Flux Facility S-Band Dual Polarization Doppler Radar Airborne Platforms Lockheed Hercules EC-130Q Lockheed L-188C Electra Airborne Research Instruments Electra Doppler Radar GPS Dropsondes

Ground-based Facilities

NCAR/ATD's standard rawinsonde system allows researchers to temporarily expand the radiosonde network maintained by the NWS and to capture local weather phenomena in support of specific research objectives. Profiles of atmospheric pressure, ambient temperature, and relative humidity are obtained from expendable radiosondes suspended below a helium-filled balloon and send back to a ground station via a radio transmitter. Wind speed and direction are measured by tracking elevation and azimuth of the radiosonde using Navigational Aid signals from either fixed transmitting stations on the ground (LORAN) or from moving satellites in space (GPS). The GLASS system also includes a meteorological surface observation station that measures the same thermodynamic state properties at ground level. ATD/SSSF operates five trailer-based and one van-based mobile GLASS.

Integrated Sounding System (ISS)

ATD's ISS was a cooperative development effort between NCAR/ATD and NOAA's Aeronomy Lab. The system combines a suite of ground-based in-situ and remote sensing instrumentation that provides a more complete description of the boundary layer and lower troposphere than standard upper-air observing systems can furnish. The following systems have been merged to obtain continuous vertical profiles of high-resolution wind, temperature, and humidity: A GLASS rawinsonde system, a 915 MHz Doppler clear-air Wind Profiler to measure horizontal and vertical wind components, a Radio Acoustic Sounding System (RASS) that produces temperature profiles, an enhanced surface meteorological station, and sophisticated communications, data processing, and display infrastructure. ATD/SSSF operates four ISS.

Integrated Surface Flux Facility (ISFF)

ATD recently merged the Atmosphere Surface Turbulent Exchange Research facility (ASTER) and the Portable Automated Mesonet (PAM III and Flux PAM) into a new facility called the ISFF. The merged facility integrates data transmission, archival, and display systems of both ASTER and PAM, which allows intensive and extensive surface flux and turbulence measurements in a single program. The stations are outfitted with wind, temperature, humidity, pressure, solar radiation, and precipitation sensors. Additional measurements of momentum fluxes, sensible and latent heat, water vapor, net radiation, soil temperature, soil moisture, and soil heat flux are possible. Solar power and satellite data transmission via GOES, as well as direct RF modem connections and packet hopping, make the ISFF suitable for remote operations almost anywhere in the world. The ISFF is managed by ATD/SSSF.

S-Band Dual Polarization Doppler Radar (S-Pol)

As the name implies, S-Pol is an S-Band radar which operates in the 10-cm wavelength, 2.7-2.9 GHz frequency range. Its high-performance transmitter is built around the FAA's ASR-9 system, which includes the ability to detect the velocity with which a target moves. The radar uses a high-quality, parabolic antenna with high gain (44.5 dB). By comparing the frequency of the received signal with the frequency of the transmitted signal, reflectivity maps are created that show the location and intensity of precipitation. S-Pol's low sidelobe performance reduces the production of erroneous echoes providing a higher quality dataset. Its dual-channel receivers, designed to detect and amplify the signals received by the antenna, receive both the co-polar and cross-polar responses simultaneously. In addition, S-Pol's improved signal processing and polarization capabilities provide information on the physical characteristics of droplets such as size, number, and shape. S-Pol differentiates itself from other Doppler weather radars through its highly innovative design. S-Pol can be packaged into 20-ft shipping containers eliminating the radome, greatly easing transportation to remote locations worldwide, and significantly lowering shipping costs. S-Pol is managed and operated by ATD/RSF.