The Atmospheric Profiling Group in ISF operates boundary layer wind profilers as part of the Integrated Sounding System (ISS) (Parsons et al 1994). They can be deployed at fixed land sites, or as part of MISS (Mobile ISS) for rapid deployment, or at sea on research ships. They are vertically pointing UHF radars designed to detect back-scatter from clear-air turbulence and precipitation, using these signals to measure both wind as a function of height, and precipitation fall speed spectra as a function of height. Using the RASS (Radio Acoustic Sounding System) extension, the profilers can also measure the virtual temperature profile.
We have three 915 MHz profilers and one 1290 MHz profiler. These are standard LAP3000 boundary layer wind profilers commonly used for lower atmospheric research and monitoring, and have been deployed at over 50 field projects since 1992. They were originally developed at the NOAA Aeronomy Lab in the 1990s (Ecklund et al, 1990), and manufactured by Radian Corp, then Vaisala (now by Scintec and Radiometrics). They use the DBS (Doppler Beam Swinging) technique to make horizontal wind measurements every 15 - 30 minutes, with vertical wind measurements available every 1 - 2 minutes. The profilers use a mix of POP4 and LapXM software for data collection, depending on the application. Data is usually post-processed using the NCAR/RAL NIMA (NCAR Improved Moments Algorithm) to remove artifacts such as clutter, interference and aliasing (Morse et al 2002).
We also operate the 449 MHz Modular Wind Profiler which is capable of more rapid wind measurement and higher height coverage - please see this link for more information on that system.
| Wind Profiler Typical Performance Specifications | |
| Radar Frequency | 915 MHz or 1290 MHz |
| Radar Wavelength | 0.33 meters |
| RF Power | 50 W average, 600 W peak |
| Antenna | 4.0 square meters, 26 dBi |
| Beam Width | 9 degrees |
| Minimum Height | 0.12 km AGL |
| Maximum Height | 2 to 5 km AGL |
| Height Resolution | |
| Low altitude mode: | 60 & 100 meters |
| High altitude mode: | 250 & 500 meters |
| Wind Speed | ~ 1 m/s |
| Wind Direction | ~ 5 degree |
| RASS Specifications | |
| Acoustic Frequency | 2000 Hz |
| Acoustic Power: | 400.0 W |
| Total Electrical Input | |
| Acoustic Beamwidth | 8.0 degrees |
Up to four sets of radar parameters can be defined for the ISS wind profiler and RASS system. These are set up interactively by the operator. The operator enters values for the inter-pulse period (IPP), the pulse width (PW), the number of heights (NHTS), the time from the first transmitted pulse to the first sampled height (DELAY), and the spacing between the sampled heights (SPACE). The four pulse widths available define the vertical resolution of the wind profiler and RASS. Those pulse widths are as follows:
The pulse width also defines the amount of energy transmitted by the radar and in most cases is reflected in the maximum altitude coverage. Another key factor in altitude coverage is the availability of scatterers to provide refractive index irregularities within the sample volume. Most variations in refractive index depend on the variation of temperature and humidity caused by turbulent eddies that are in a size range on the order of one-half the radar wavelength.
REFS:
Ecklund, W.L., D.A. Carter, B.B. Balsley, P.E. Currier, J.L. Green, B.L. Weber, and K.S. Gage, 1990: Field tests of a lower tropospheric wind profiler, Radio Sci., 25, 899-906.
Morse, C.S., R.K. Goodrick, and L.B. Cornman, 2002: The NIMA method for improved moment estimation from Doppler spectra, J. Atmos. Ocean. Technol., 19, 274-295.
Parsons, D., et al., 1994: The Integrated Sounding System: Description and preliminary observationsfrom TOGA COARE, Bull. Am. Meteorol. Soc., 75, 553-567.
Vaisala LAP3000 brochure (note: this instrument is no longer manufactured by Vaisala)
2015 - 2017: Upgrade from POP4 to LapXM electronics and software.
