Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish

<div>Deviations of two-way absorption attenuations (<svg height="8.68572pt" id="M138" style="vertical-align:-0.0498209pt" version="1.1" viewbox="-0.0498162 -8.6359 17.6372 8.68572" width="17.6372pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M600 0V24L339 665L311 657L43 24V0H600ZM497 50H107L303 539L497 50Z" id="g113-133"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="641" vert-adv-y="641"></glyph.data></g><g transform="matrix(.013,0,0,-0.013,8.327,0)"><path d="M686 28C612 35 607 44 591 112C563 234 541 360 519 489L489 666L457 658L147 121C100 40 89 36 24 28L17 0H240L250 28C168 34 159 41 190 101L262 237H482C495 180 503 137 510 91C517 47 514 35 441 28L433 0H677L686 28ZM475 280H285L429 541H431L475 280Z" id="g113-66"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="703" vert-adv-y="703"></glyph.data></g></svg>) at North′ sea for six frequencies from the attenuation computed by using a fixed absorption coefficient of North, Spring, and 50 m depth. The line labels are shown in 800 kHz panel. The dotted vertical lines are drawn at the rough maximum ranges with 20 dB SNR shown in Figure <a href="../fig4/">4</a>.</div>

International Journal of Oceanography

fig9

Figure 9

Figure 9: Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish 