. Compendium of meteorology. Meteorology. '°°i>MjJWi^. 8 10 12 15 i 20 24 30 8 10 12 15 20 24 30 WAVE PERIOD IN SECONDS Fig. 5.—Spectrograms of waves recorded during 14-16 March 1945 at Pendeen, England [1]. Each spectrogram gives the dis- tribution of energy among wave periods for a 20-minute record. The records were taken at 2-hourIy intervals. traveled in a general northeast direction, passing west of the British Isles. Four representative weather maps are shown in Figs. 6-9. The positions indicated for the "fetches" were determined according to the rules de- veloped for wave f
. Compendium of meteorology. Meteorology. '°°i>MjJWi^. 8 10 12 15 i 20 24 30 8 10 12 15 20 24 30 WAVE PERIOD IN SECONDS Fig. 5.—Spectrograms of waves recorded during 14-16 March 1945 at Pendeen, England [1]. Each spectrogram gives the dis- tribution of energy among wave periods for a 20-minute record. The records were taken at 2-hourIy intervals. traveled in a general northeast direction, passing west of the British Isles. Four representative weather maps are shown in Figs. 6-9. The positions indicated for the "fetches" were determined according to the rules de- veloped for wave forecasting.^ It should be noted that the fetch lengthened during the time interval between 1830,11 March, and 1830, 12 March. The spectrogram in Fig. 5 can be interpreted in terms of the classical wave theory, according to which com- ponent wave trains travel independently with the group 7. A different type of analysis based on the autocorrelation function has recently been applied to ocean waves by Seiwell and Wadsworth [14]. V = 4x by) Ls (10) Here Xy, and x, represent the location of a point dis- turbance and the wave station, respectively; U and ts the time of the disturbance and the time at which waves of period T arrived at the wave station. Equation (10) has a simple geometric interpretation on a time-distance. Fig. 6.—Surface weather map for 10 March 1945. Fronts are represented in the conventional manner, and isobars are labeled in millibars. Point P denotes the wave station at Pendeen, England. Figs. 6-9 show the passage across the Atlan- tic Ocean of the storm for which the wave spectrograms are shown in Fig. 5. {From Munk [9].) diagram (Fig. 10): Rays through the point source represent the paths of wave periods, the value of each period being determined by the slope of the ray. The measurement of two periods, Ti and T^, arriving at times and ^^,2, suffices to determine distance and time of the Please note that these images are extracted from sca
Size: 1830px × 1365px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectmeteorology
