<DATE_RANGE> 10 Jan to 26 Jan 2001
A. at ship speed 2.0 to 2.5 kts
1) Discrete acoustic transects were done at each station simultaneously with the 2-M and 1-M net tows, for the 200.*, 300.*, 400.*, 500.* and 600.* cardinal lines. Some stations only had 2-M net tows and thus only 1 acoustic transect due to time constraints (N=10: 200.000, 200.020, 200.160, 300.140, 300.160, 300.180, 500.140, 500.160, 500.200, 500.220). There was 1 additional transect on the seaward edge of the 500.* line, and 1 transect associated with a tow near Avian I. Total of 87 transects.
2) Palmer nearshore transects A-E and F-J once each at the beginning of the cruise. Total of 2 transects.
B. At ship speed 4.0 to 4.5 kts
1) Continuous acoustic transects simultaneously with seabird observations over region of high density grid 1 as established in Jan 1995. Total of 23 transects.
2) Continuous acoustic transects simultaneously with seabird observations on the nearshore picket line (at 3.7 km radius from Torgersen I) and the 10 km picket line (at 10 km radius). Total of 13 transects.
<VARIABLES>
There are two event_bld.lists, one for the regular straight transects where the distance calculated from the beginning and ending latitudes and longitudes (01jan) and one for the curved nearshore transects where the distance is calculated from the sum of multiple recordings of the latitude and longitude. The end latitude in the event_bld.list 01janpal is what the end latitude would be if the transect were straight to allow for distance calculations.
B. The calibration files give the calibration constants: Variables are: BeamPatternFactor Rcvr1_G120logR Rcvr1_G140logR Rcvr2_G120logR Rcvr2_G140logR Rcvr3_G120logR SrcLevel_at0dB SrcLevel_at-3dB SrcLevel_at-6dB SrcLevel_at-10dB SrcLevel_at-13dB 20/40CrossoverPt
<DERIVED_VARIABLES>
<SAMPLING_FREQUENCY>
There were a total of 123 bioacoustic events in 01Jan. One short (1.7-2 km) acoustic transect was conducted in conjunction with net tows at each Palmer LTER station occupied during the cruise. Station spacing was 20 km along the cardinal lines which are 100 km apart. The high density (HD) foraging grid, 10 by 20 km with the longer distance moving offshore, is within the foraging range of the Adelie penguins nesting at Palmer Station. During the HD grid, 10 km transects parallel to shore were connected by shorter 5 km connecting transects. The HD grid was completed on 26 Jan. The Palmer nearshore transects were only done at the beginning the cruise. Two picket lines were run, nearshore and 10 km on 25 Jan.
(1) collection of data
The acoustic system consists of a BioSonics Model 102 echo sounder connected to a downward looking 120 kHz transducer which was deployed with a tow body several meters below the surface. The towbody was deployed with the research vessels Laurence M. Gould. The sounder was operated with a 20 log R (R = range in m) time-varied-gain (TVG) function to compensate for one-way acoustic spreading loss.
(2) archival process
The analog voltage signals received by the echosounder are processed in the field through an interface tape unit that records a digitized version of each signal onto a digital audio tape (DAT) recorder. The DAT tapes can be replayed with the Biosonics Echo Signal Processing (ESP) software package for calculation of Sum Squared Voltage (SSV) data if a file is lost or if a different configuration file is desired.
(3) primary processing of data:
Echo integration of the returned acoustic energy (volts) was done with the BioSonics Model 221 Echo Signal Processor, and ESP version 3 on a Dec 486 computer on board. The system was configured to integrate voltage measurements over 2-m depth intervals and several pings. These integrated values were used to generate a two-dimensional (alongtrack, vertical) matrix of volume scattering data (VSD, m3 m-3) for each acoustic transect, according to algorithms described in Apprendix C of BioSonics. When in deep water (200 m) data was collected without a bottom algorithm. In shallow water, a bottom algorithm was used to automatically separate the bottom and biotic signal.
(4) calibration of the system was done by BioSonics ( Seattle, WA) in a tank at ambient temperature. Calibration was done for each of the six deck and tow cable combinations. The calibrations bracketing the use of the equipment were done on June 12, 2000 and June 19, 2001. There were only small differences in the calibrations. During 01Jan, the OldDeck/OldTow cable combination was used exclusively. The Deck cables are 100' long, the Tow cables 218' long - New Deck (S/N#141-94-870) - New Tow (S/N#147-94-156) - Old Deck (S/N#141-92-740) - Old Tow (S/N#147-92-137)
<EXPERIMENTAL_DESIGN>
Acoustic transects on stations were conducted within 4 hours of the time other LTER data sets were collected. Each of these acoustic transects was matched with a net tow to allow identification of potential scatterers and the size distribution of Euphausia superba, the dominant scatterer. The high density grid was run continuously and at a higher speed to accommodate the requirements of the seabird observers. The high density grid is conducted during presumed peak penguin chick growth periods. The picket line transects are semi-circles at 3.7 and 10 km from the Adelie penguins rookery at Torgersen Island.
<FILE_FORMAT>
1) event_bld.list ascii, space delimited (number of columns)! 01jan and identifying information; rows with column headers and the units of the parameter data follow
2) calibration files ascii, space delimited
3) VSD acoustic matrix for each event; binary file with results from echo integration of the voltage returning to the echo sounder. the data stored is mean voltage squared for each depth strata and ping.
<STORAGE_LOCATION> The event_bld.list and calibration files are in: ~lter/data/01jan/bioacoustics and Velella on the MSILTER Apple talk network. The VSD files are stored on a hard disk off line until room is available on line. They may be accessed by contacting Karen Baker, data manager for the Palmer LTER.
<FILE_NAMES>
(1) event_bld.list
(2) acoCalib.* files named: acoCalib.(date of calibration)(cable combination)
(3) rawdata/(event#).dat the VSD acoustic matrix for each transect is named by the event
<PRINCIPAL_INVESTIGATORS> Robin M. Ross, Langdon B. Quetin
<ASSOCIATE_INVESTIGATORS> none <CONTACT_PERSON> Robin M. Ross, Langdon B. Quetin
<SAMPLES_COLLECTED_BY> S. Oakes, C. Holmes, J. Watson, R. M. Ross, Brian Fredin, Holly Rodriguez
<LAB_ANALYSIS_BY> RM Ross and LB Quetin
<DATA_ENTRY_BY> field team
<DATA_ANALYSIS_BY>
<SUBMITTED_BY RM Ross
<DATE_SUBMITTED> 26 June 2003
<DATES_UPDATED>
<SUPPORTING_DOCUMENTS>
BioSonics (1990) BioSonics Echo Signal Processor Operators Manual. BioSonics, Inc., Seattle, WA, 373 pp.
Lascara (1996) Seasonal and mesoscale variability in the distribution of Antarctic krill, Euphausia superba, west of the Antarctic Peninsula. Ph. D. Thesis, Old Dominion University. 167 pp.
Lascara, CM, EE Hofmann, RM Ross, LB Quetin (1999) Seasonal variability in the distribution of Antarctic krill, Euphausia superba, west of the Antarctic Peninsula. Deep-Sea Res. 46: 951-984.
Greene, C. H., T. K. Stanton, P. H. Wiebe and S. McClatchie (1991) Acoustic estimates of Antarctic krill. Nature 349: 110.
Nero, R. W. and J. J. Magnuson (1989) Characterization of patches along transects using high resolution 70 kHz integrated acoustic data. Canadian Journal of Fisheries and Aquatic Sciences 46: 2056-2064.
Wiebe, P. H., C. H. Greene, T. K. Stanton and J. Burczynski (1990) Sound scattering by live zooplankton and micronekton: empirical studies with a dual-beam acoustical system. Journal of Acoustical Society of America 88: 2346-2360.
<QUALITY_ASSURANCE>