/*-------------------------------------------------------------------- * The MB-system: mbabsorption.c 2/10/2008 * $Id: mbabsorption.c 1770 2009-10-19 17:16:39Z caress $ * * Copyright (c) 2008-2009 by * David W. Caress (caress@mbari.org) * Monterey Bay Aquarium Research Institute * Moss Landing, CA 95039 * and Dale N. Chayes (dale@ldeo.columbia.edu) * Lamont-Doherty Earth Observatory * Palisades, NY 10964 * * See README file for copying and redistribution conditions. *--------------------------------------------------------------------*/ /* * MBabsorption calculates the absorption of sound in sea water in dB/km * as a function of frequency, temperature, salinity, sound speed, and depth. * * We use the Francois and Garrison equations from: * Francois, R.E., Garrison, G.R., "Sound absorption based * on ocean measurements: Part I: Pure water and magnesium * sulfate contributions", J. Acoust. Soc. Am., 72(3), * 896-907, 1982. * Francois, R.E., Garrison, G.R., "Sound absorption based * on ocean measurements: Part II: Boric acid contribution * and equation for total absorption", J. Acoust. Soc. Am., * 72(6), 1879-1890, 1982. * * Francois and Garrison [1982] model the sound absorption in * sea water as resulting from contributions from pure water, * magnesium sulfate, and boric acid. The boric acid contribution * is significant below 10 kHz. The equations are: * * absorption = Boric Acid Contribution * + MbSO4 Contribution * + Pure Water Contribution * * ************************** * * Boric Acid Contribution * AlphaB = Ab * Pb * Fb * f**2 * ------------------- * f**2 + Fb**2 * * Ab = 8.86 / c * 10**(0.78 * pH - 5) (dB/km/kHz) * Pb = 1 * Fb = 2.8 * (S / 35)**0.5 * 10**(4 - 1245 / Tk) (kHz) * * ************************** * * MgSO4 Contribution * AlphaM = Am * Pm * Fm * f**2 * ------------------- * f**2 + Fm**2 * * Am = 21.44 * S * (1 + 0.025 * T) / c (dB/km/kHZ) * Pm = 1 - 0.000137 * D + 0.0000000062 * D**2 * Fm = (8.17 * 10**(8 - 1990 / Tk)) / (1 + 0.0018 * (S - 35)) (kHz) * * ************************** * * Pure Water Contribution * AlphaW = Aw * Pw * f**2 * * For T <= 20 deg C * Aw = 0.0004397 - 0.0000259 * T * + 0.000000911 * T**2 - 0.000000015 * T**3 (dB/km/kHz) * For T > 20 deg C * Aw = 0.0003964 - 0.00001146 * T * + 0.000000145 * T**2 - 0.00000000049 * T**3 (dB/km/kHz) * Pw = 1 - 0.0000383 * D + 0.00000000049 * D**2 * * ************************** * * f = sound frequency (kHz) * c = speed of sound (m/s) * =~ 1412 + 3.21 * T + 1.19 * S + 0.0167 * D * T = temperature (deg C) * Tk = temperature (deg K) = T + 273 (deg K) * S = salinity (per mil) * D = depth (m) * * ************************** * * Author: D. W. Caress * Date: February 10, 2008 * R/V Zephyr * Hanging out at the channel entrance to La Paz, BCS, MX * helping out as MBARI tries to save the grounded * R/V Western Flyer. * Note: as I was writing this code the Flyer was refloated * and successfully backed off the reef. * * $Log: mbabsorption.c,v $ * Revision 5.0 2008/02/12 02:33:49 caress * Initial version. * * */ /* standard include files */ #include #include #include #include /* mbio include files */ #include "../../include/mb_status.h" #include "../../include/mb_define.h" static char rcs_id[] = "$Id: mbabsorption.c 1770 2009-10-19 17:16:39Z caress $"; /*--------------------------------------------------------------------*/ int main (int argc, char **argv) { char program_name[] = "MBabsorption"; char help_message[] = "MBabsorption calculates the absorption of sound in sea water\nin dB/km as a function of frequency, temperature, salinity, \nsound speed, pH, and depth."; char usage_message[] = "mbabsorption [-Csoundspeed -Ddepth -Ffrequency -Pph -Ssalinity -Ttemperature -V -H]"; extern char *optarg; int errflg = 0; int c; int status; int verbose = 0; int help = 0; int flag = 0; int error = MB_ERROR_NO_ERROR; FILE *outfp; /* control parameters */ double absorption; /* absorption (dB/km) */ double frequency; /* frequency (kHz) */ double temperature; /* temperature (deg C) */ double salinity; /* salinity (per mil) */ double soundspeed; /* speed of sound (m/sec) */ double depth; /* depth (m) */ double ph; /* pH */ /* set defaults */ frequency = 200.0; temperature = 10.0; salinity = 35.0; soundspeed = 0.0; depth = 0.0; ph = 8.0; /* process argument list */ while ((c = getopt(argc, argv, "VvHhC:c:D:d:F:f:P:p:S:s:T:t:")) != -1) switch (c) { case 'H': case 'h': help++; break; case 'V': case 'v': verbose++; break; case 'C': case 'c': sscanf (optarg,"%lf", &soundspeed); flag++; break; case 'D': case 'd': sscanf (optarg,"%lf", &depth); flag++; break; case 'F': case 'f': sscanf (optarg,"%lf", &frequency); flag++; break; case 'P': case 'p': sscanf (optarg,"%lf", &ph); flag++; break; case 'S': case 's': sscanf (optarg,"%lf", &salinity); flag++; break; case 'T': case 't': sscanf (optarg,"%lf", &temperature); flag++; break; case '?': errflg++; } /* if error flagged then print it and exit */ if (errflg) { fprintf(stderr,"usage: %s\n", usage_message); error = MB_ERROR_BAD_USAGE; exit(error); } /* set output stream */ if (verbose <= 1) outfp = stdout; else outfp = stderr; /* print starting message */ if (verbose == 1 || help) { fprintf(outfp,"\nProgram %s\n",program_name); fprintf(outfp,"Version %s\n",rcs_id); fprintf(outfp,"MB-system Version %s\n",MB_VERSION); } /* print starting debug statements */ if (verbose >= 2) { fprintf(outfp,"\ndbg2 Program <%s>\n",program_name); fprintf(outfp,"dbg2 Version %s\n",rcs_id); fprintf(outfp,"dbg2 MB-system Version %s\n",MB_VERSION); fprintf(outfp,"dbg2 Control Parameters:\n"); fprintf(outfp,"dbg2 verbose: %d\n",verbose); fprintf(outfp,"dbg2 help: %d\n",help); fprintf(outfp,"dbg2 frequency: %f\n",frequency); fprintf(outfp,"dbg2 temperature:%f\n",temperature); fprintf(outfp,"dbg2 salinity: %f\n",salinity); fprintf(outfp,"dbg2 soundspeed: %f\n",soundspeed); fprintf(outfp,"dbg2 depth: %f\n",depth); fprintf(outfp,"dbg2 ph: %f\n",ph); } /* if help desired then print it and exit */ if (help) { fprintf(outfp,"\n%s\n",help_message); fprintf(outfp,"\nusage: %s\n", usage_message); exit(error); } /* call function to calculate absorption */ status = mb_absorption(verbose, frequency, temperature, salinity, depth, ph, soundspeed, &absorption, &error); /* print it out */ if (verbose > 0) { fprintf(outfp,"\nProgram <%s>\n",program_name); fprintf(outfp,"Version %s\n",rcs_id); fprintf(outfp,"MB-system Version %s\n",MB_VERSION); fprintf(outfp,"Input Parameters:\n"); fprintf(outfp," Frequency: %f kHz\n",frequency); fprintf(outfp," Temperature: %f deg C\n",temperature); fprintf(outfp," Salinity: %f per mil\n",salinity); if (soundspeed > 0.0) fprintf(outfp," Soundspeed: %f m/sec\n",soundspeed); fprintf(outfp," Depth: %f m\n",depth); fprintf(outfp," pH: %f\n",ph); fprintf(outfp,"Result:\n"); fprintf(outfp," Sound absorption: %f dB/km\n",absorption); } else { fprintf(outfp, "%f\n", absorption); } /* print output debug statements */ if (verbose >= 2) { fprintf(outfp,"\ndbg2 Program <%s> completed\n", program_name); fprintf(outfp,"dbg2 Ending status:\n"); fprintf(outfp,"dbg2 status: %d\n",status); } /* end it all */ exit(error); } /*--------------------------------------------------------------------*/