11/28/2023 0 Comments Us weather dopplerIn 1974, based on Rummler’s scheme, Groginsky (1972), Lhermitte (1972), and Novick and Glover (1975) placed into operation the first multichannel pulse pair processor (PPP) at the AFCRL. In signal processing, important mathematical underpinnings had been provided by Cooley and Tukey (1965), developers of the fast Fourier transform, and by the real-time Doppler velocity processing schemes of Rummler (1968a, b, c) and Miller and Rochwarger (1972). Keystone research in the structure of mesocyclones ( Burgess 1976) and tornado vortices ( Brown and Lemon 1976), combined with an abundance of severe storms in Oklahoma, helped NSSL set the stage for the Joint Doppler Operational Project (JDOP) by providing the fundamental knowledge of storm dynamics, based on dual-Doppler information, that was necessary before single-Doppler schemes could be tested in JDOP. The first reported tornado vortex signature was associated with the Union City tornado ( Burgess et al. Using these radars, Burgess, Brown, and others frequently observed mesocyclone signatures and produced some of the first real-time Doppler displays. NSSL added a similar system at Cimarron Field, 42 km northwest of NSSL, in 1973, with full dual-Doppler operations beginning in 1974. In 1971, NSSL put into operation their first S-band Doppler weather radar designed specifically for severe storm studies ( Sirmans and Doviak 1973). The initial experiments used an X-band system with a comb filter for spectral analysis of the echoes this system used the same trailer and some of the hardware employed in the Smith and Holmes (1961) experiments (E. Investigations by the Weather Bureau to determine desirable characteristics of a Doppler weather radar and its utility in meteorology were continued in the 1960s at the National Severe Storms Laboratory (NSSL) (e.g., Lhermitte and Kessler 1964). Kraus (1973) identified the Brookline, Massachusetts tornado of 1972 based on its vortex signature. Based on this, Donaldson (1970) developed a set of minimum values of shear, persistence, and vertical extent as requisites for identification of a mesocyclone signature. Donaldson (1970) investigated Doppler radar’s ability to resolve vortices of different sizes and showed that the mesocyclone, which Fujita and others had linked with tornadoes, could be identified at more distant ranges than the smaller tornado vortex signature could. Using the PSI, the first mesocyclone detected by Doppler radar was recorded on 9 August 1968 ( Donaldson et al. The PSI employed a coherent memory filter (CMF) to make coarse, real-time Doppler spectral analyses over the entire range of the radar ( Chimera 1960 Atlas 1963 Groginsky 1965, 1966). A signal and data processor called the plan shear indicator (PSI) ( Armstrong and Donaldson 1969) was developed in connection with the Porcupine Doppler to enable the Doppler data to be displayed in real time. In 1961, the Air Force Cambridge Research Laboratories (AFCRL) put into operation a 5-cm pulsed Doppler radar called Porcupine that was adapted for meteorological measurements. Rogers (1990) reviews the history of early efforts to apply Doppler techniques in radar meteorology. Thus, operational use of Doppler weather radar had to await the development of pulse-Doppler technology (that provided the range capability) for the extraction of moments such as mean radial velocity and spectrum width from pulse Doppler spectra and techniques for interpreting the velocity patterns observable with a single radar. The inability of a CW radar system to determine the range to the target was a serious impediment to operational application of this capability. Although plagued by noisy magnetrons and attenuation by rain, these early systems were capable of detecting 205-mph (∼30 km h −1) winds near a tornado vortex ( Holmes and Smith 1958 Rockney 1960 Smith and Holmes 1961). This early effort involved conducting tests on an experimental, 3-cm, continuous-wave (CW) Doppler weather radar system at Wichita Falls, Texas, and Wichita, Kansas. The Weather Bureau followed up on this potential beginning in fall 1956 and continued through 1960. This offered a potential for remote measurement of wind speeds. The wartime Rad Lab investigators recognized the possibility that radar systems could employ the Doppler effect to measure target velocities. Advances made by Doppler radar meteorological research
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