S5 Event

Event S5 is a source tow along an isobath during the SWellEx-96 Experiment. During this event, there were no loud interferers present. The source ship (R/V Sproul) started its track south of all of the arrays and proceeded northward at a speed of 5 knots (2.5 m/s). Most of the source tow track occurred in water between 180 and 220 meters deep, with the second half of the tow along the 180 m isobath.


Two sources were simultaneously towed by the R/V Sproul: a "deep" source (J-15) and a "shallow" source (J-13).

The deep source was towed at a depth of about 54 m. It transmitted numerous tonals of various source levels between 49 Hz and 400 Hz. This tonal set is known as T-49-13. The T-49-13 tonal pattern consists of 5 sets of 13 tones. Each set of 13 tones spans the frequencies between 49Hz and 400Hz. The first set of 13 tones is projected at maximum level and is referred to as the "High Tonal Set." These tones are projected with transmitted levels of approximately 158 dB. The second set of tones are projected with levels of approximately 132 dB. The subsequent sets (3rd, 4th, and 5th) are each projected 4 dB down from the
previous set.

T-49-13 Source Frequencies (Hz)

49 64 79 94 112 130 148 166 201 235 283 338 388 <-- High Signal Level
52 67 82 97 115 133 151 169 204 238 286 341 391 <-- 2nd Set of Tonals
55 70 85 100 118 136 154 172 207 241 289 344 394 <-- 3rd Set of Tonals
58 73 88 103 121 139 157 175 210 244 292 347 397 <-- 4th Set of Tonals
61 76 91 106 124 142 160 178 213 247 295 350 400 <-- 5th Set of Tonals

Aside: At the beginning, midway point, and end of the track, the deep source stopped projecting CW tones and started projected FM chirps.

The shallow source was towed at a depth of about 9m. It transmitted 9 frequencies between 109 Hz and 385 Hz, known as the C-109-9S tonal set.

The C-109-9S Source Frequencies (Hz)

109 127 145 163 198 232 280 335 385 <-- Shallow Source Frequencies

Some initial post-processing utilized so-called "noise frequencies." Those frequencies chosen to be representative of the noise field are listed below:

Noise Frequencies Processed (Hz)

62 77 92 107 125 143 161 179 214 248 296 351 401


The vertical array (VLA) and tilted array (TLA) both recorded the full 75 minute event, while the two horizontal arrays (HLA North and South) recorded only the last 50 minutes. For the VLA and TLA, the start time of Event S5 is J131, 23:15 GMT. The HLA data begins at J131, 23:40 GMT. Note: Day J131 corresponds to 5/10/96.


A sound speed profile was generated from a local CTD cast, file "i9606.prn":

10 May
21:05 PST
32d39.12' N
117d22.11' W
21:21 PST
32d38.73' N
117d22.11' W

Alternatively, the CTD cast from Station 5, file "i9605.prn," would be an even more appropriate choice due to its temporal and spatial proximity to the source tow event.

The sound speed data was salinity-despiked and depth-interpolated to every half meter.

The geoacoustic parameters were derived from a database of soundings and grainsizes. For more details on waveguide parameters, click on the "Environment" link in the navigation bar at the top of this page.


The array data below is in SIO format. The MATLAB M-file "sioread.m" can be used to read the data into MATLAB.

File Size
J1312315.vla.21els.sio.gz 338 MB 21-element subarray of the VLA
J1312315.tla.22els.sio.gz 376 MB 22-element subarray of the TLA
J1312340.hla.north.sio.gz 369 MB HLA North, bad elements removed
J1312340.hla.south.sio.gz 383 MB HLA South, bad elements removed

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