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<br />wave motion ranging from 11 to 40 ms-1 near frontal zones and <br />associated with the fronts' vertical wind shear. Figure 3 shows <br />Gossard's results for the synoptic case illustrated using a vertical <br />pointing radar. This time-section clearly defines the critical <br />features of wavelength, amplitude, and period of these waves. <br />Smaller gravity waves having wavelengths of 5.5 km and amplitudes of <br />120 m with vertical velocity fluctuations of :0.5 ms-1 have been <br />measured by Doppler techniques (Kjelaas et al., 1974). <br /> <br />At the 1978 Conference on Meteorological Observations and Instrumenta- <br />tion more than six papers were presented which showed examples of <br />gravity waves observed in the planetary boundary layer (PBL) using <br />acoustic sounders and SODAR. The most dramatic example of these <br />observations occurred in the Hanford Meteorological Station using a <br />sounder fabricated by the NOAA-ERL wave propagation laboratory. <br />Waves of double amplitude of 200 m were observed in the PBL under <br />stable conditions (Hadlock, 1978, see figure 4). <br /> <br />IV. Satellite Observations <br /> <br />Satellite observations of gravity WaVE!S by Thomas et ale (l975) have <br />shown similar characteristics as earlier observations. Thomas found <br />that gravity waves observed on medium resolution ATS-3 film loops <br />had average translational speeds of 17' ms-1, wavelengths of 150 km, <br />and periods of 2.5 hours. Table 1 provides typical characterisics <br /> <br />5 <br />