This dataset contains acoustic recordings from Directional Frequency Analysis and Recording (DIFAR) sonobuoys that were deployed from 30 January – 23 March 2021 during the TEMPO voyage. 251 sonobuoys were deployed yielding 460 hours of acoustic recordings. Three models of sonobuoys were used during the voyage: AN/SSQ-53F sonobuoy from SonobuoyTechSystems, USA (made in 2011; identifiable by tall black housing); Q53F sonobuoys from Ultra Electronics Australia (made in 2011 for Australian Defence; identifiable by tall silver housing); SDSQ955 (HIDAR) sonobuoys from Ultra Electronics UK (re-lifed in 2018; identifiable from small silver housing); During TEMPO, recordings were made by deploying above sonobuoys in DIFAR (standard) mode while the ship was underway (Gedamke and Robinson 2010, Miller et al. 2015). During transit, listening stations were conducted every 30 nmi in water depths greater than 200 m when Beaufort sea state was less than 7. Sonobuoys were occasionally deployed with spacing less than 30 nmi in an attempt to more precisely determine spatial extent and vocal characteristics of calls that were believed to be coming from animals relatively close to the ship’s track. During marine science stations, sonobuoys were deployed approximately 2-4 nmi prior to stopping in order to attempt to monitor them for the full six-eight hour duration of their operational life or the duration of the station. The sampling regime was chosen for compatibility with previous surveys, and to balance spatial resolution with the finite number of sonobuoys available for this study. Instrumentation, software, and data collection At each listening station, a sonobuoy was deployed with the hydrophone set to a depth near 140 m. Sonobuoys transmitted underwater acoustic signals from the hydrophone and directional sensors back to the ship via a VHF radio transmitter. Radio signals from the sonobuoy were received using an omnidirectional VHF antenna (PCTel Inc. MFB1443; 3 dB gain tuned to 144 MHz centre frequency) and a Yagi antenna (Broadband Propagation Pty Ltd, Sydney Australia) mounted on the aft handrail of the flying bridge. The antennas were each connected to a WiNRADiO G39WSBe sonobuoy receiver via low-loss LMR400 coaxial cable via a cavity filter with 1 MHz passband centered on 144 MHz. The radio reception range on the Yagi antenna was similar to previous Antarctic voyages, and was adequate for monitoring and localisation typically out to a range of 10-12 nmi, provided that the direction to the sonobuoy was close (i.e. within around 30o) to the main axis of the antenna. The radio reception on the omnidirectional antenna typically provided 5-10 nmi of omnidirectional reception from sonobuoys. At transit speed (8-11 knots), the Yagi antenna provided about 75 minutes of acoustic recording time per sonobuoy. Using both antennas together were able obtain radio reception for up to six hours (i.e. the maximum life of a 955 sonobuoy) when sonobuoys were deployed within 5 nmi of a marine science station. Received signals were digitised via the instrument inputs of a Fireface UFX sound board (RME Fireface; RME Inc.). Digitised signals were recorded on a personal computer as 48 kHz 24-bit WAV audio files using the software program PAMGuard (Gillespie et al. 2008). Data from both the Yagi and Omnidirectional antenna were recorded simultaneously as WAV audio channels 0 (left) and 1 (right). Each recorded WAV file therefore contains a substantial amount of duplication since both antennas and receivers were usually receiving the same signals from the same sonobuoy. Directional calibration The magnetic compass in each sonobuoy was not calibrated/validated upon deployment because the ship did not generate enough noise. Intensity calibration Intensity calibration and values followed those described in Rankin et al (2019). Sonobuoy deployment metadata The PAMGuard DIFAR Module (Miller et al. 2016) was used to record the sonobuoy deployment metadata such as location, sonobuoy deployment number, and audio channel in the HydrophoneStreamers table of the PAMGuard database (IN2021_V01_Difar-2021-01-22.sqlite3). A written sonobuoy deployment log (SonobuoyLog.pdf) was also kept during the voyage, and this includes additional notes and additional information not included in the PAMGuard Database such as sonobuoy type, and sonobuoy end-time. Real-time monitoring and analysis: Aural and visual monitoring of audio and spectrograms from each sonobuoy was conducted using PAMGuard for at least 5 minutes after deployment only to validate that the sonobuoy was working correctly. Additional information about sonobuoys is contained in the file: Sonobuoy data collection during the TEMPO voyage - 2021-01-15.pdf References Greene, C.R.J. et al., 2004. Directional frequency and recording ( DIFAR ) sensors in seafloor recorders to locate calling bowhead whales during their fall migration. Journal of the Acoustical Society of America, 116(2), pp.799–813. Miller, B.S. et al., 2016. Software for real-time localization of baleen whale calls using directional sonobuoys: A case study on Antarctic blue whales. The Journal of the Acoustical Society of America, 139(3), p.EL83-EL89. Available at: http://scitation.aip.org/content/asa/journal/jasa/139/3/10.1121/1.4943627. Miller, B.S. et al., 2015. Validating the reliability of passive acoustic localisation: a novel method for encountering rare and remote Antarctic blue whales. Endangered Species Research, 26(3), pp.257–269. Available at: http://www.int-res.com/abstracts/esr/v26/n3/p257-269/. Rankin, S., Miller, B., Crance, J., Sakai, T., and Keating, J. L. (2019). “Sonobuoy Acoustic Data Collection during Cetacean Surveys,” NOAA Tech. Memo. NMFS, SWFSC614, 1–36.

During the 2013 Antarctic Blue Whale Voyage Acousticians noted all whale calls and other acoustic events that were detected during real-time monitoring in a Sonobuoy Event Log. The acoustic tracking software, difarBSM, stored processed bearings from acoustic events and cross bearings in tab delimited text files. Each event was assigned a classification by the acoustician, and events for each classification were stored in separate text files. The first row in each file contains the column headers, and the content of each column is as follows: buoyID: Buoy ID number is the number of the sonobuoy on which this event was detected. This can be used as a foreign key to link to the sonobuoy deployment log. timeStamp_matlabDatenum: Date and time (UTC) at the start of the event represented as a Matlab datenum (i.e. number of days since Jan 0 0000). Latitude: Latitude of the sonobuoy deployment in decimal degrees. Southern hemisphere latitudes should be negative. Longitude: Longitude of sonobuoy deployment in decimal degrees. Western hemisphere longitudes should be negative. Altitude: Depth of the sonobuoy deployment in metres. For DIFAR sonobuoys either 30, 120 or 300. magneticVariation_degrees: The estimated magnetic variation of the sonobuoy in degrees at the time of the event. Positive declination is East, negative is West. At the start of a recording this will be entered from a chart. As the recording progresses, this should be updated by measuring the bearing to the vessel. bearing_degreesMagnetic: Magnetic bearing in degrees from the sonobuoy to the acoustic event. Magnetic bearings were selected by the acoustician by choosing a single point on the bearing-frequency surface (AKA DIFARGram) produced by the analysis software difarBSM. frequency_Hz: The frequency in Hz of the magnetic bearing that the acoustician selected from the bearing-frequency surface (DIFARGram). logDifarPower: The base 10 logarithm of the height of the point on the DIFARGram receiveLevel_dB: This column contains an estimate of the The RMS receive level (dB SPL re 1 micro Pa) of the event. Received levels were estimated by applying a correction for the shaped sonobuoy frequency response, the receiver’s frequency response, and were calculated over only the frequency band specified in each classification (see below). soundType: soundType is the classification assigned to the event by the acoustician. Analysis parameters for each classification are included in the csv file classificationParameters.txt. The columns of this file are as follows: outFile: The name of the tab-separated text file that contains events for this classification. analysisType: A super-class describing the broad category of analysis parameters soundType: The name of the classification sampleRate: When events are processed, they are downsampled to this sample rate (in Hz) in order to make directional processing more efficient and precise FFTLength: The duration (in seconds) used for determining the size of the FFT during difar beamforming (i.e. creation of the DIFARGram). numFreqs: Not used during this voyage targetFreq: The midpoint of the frequency axis (in Hz) displayed in the DIFARGram Bandwidth: This describes the half-bandwidth (Hz) of the frequency axis of the DIFARGram. The frequency axis of the DIFARGram starts at targetFreq-bandwidth and ends at targetFreq + bandwidth frequencyBands_1: The lower frequency (Hz) used for determining RMS received level. frequencyBands_2: The upper frequency (Hz) used for determining RMS received level. preDetect: Duration of audio (in seconds) that will be loaded before the start of the event. The processed audio includes the time-bounds of the event marked by the acoustician as well as preDetect seconds before the start of the event. postDetect: Duration of audio (in seconds) that will be loaded after the end of the event. The processed audio includes the time-bounds of the event marked by the acoustician + postDetect seconds.

This dataset contains acoustic recordings from Directional Frequency Analysis and Recording (DIFAR) sonobuoys that were deployed throughout the 2012 Blue Whale Voyages conducted off Portland, Victoria, Australia from January – March (in the Bonney Upwelling). During the 20 days at sea 131 AN/SSQ-53D sonobuoys were deployed yielding more than 500 hours of acoustic recordings. In January a total team of three dedicated acousticians monitored round-the-clock for blue whales and in all weather conditions. In March the team size was increased so that five acousticians monitored and tracked blue whales round-the-clock. The recording chain for all sonobuoy deployments through 25 March 2012 included a 3-dB communications antenna with a central frequency at 161 MHz and masthead amplifier connected to a passive four way splitter. The highest point of the antenna was approximately 14 m above sea level. The antenna, amplifier, and splitter were connected with low loss cable, and each output of the four way splitter connected to the DIFAR input of a WiNRaDiO 2902i sonobuoy VHF receiver. On 25 March the masthead amplifier failed and was removed from the recording chain. This failure prompted the use of recently acquired WiNRaDiO G39WSBe sonobuoy receivers. The A/D converter used throughout both voyages was a RME Fireface UFX. The voltage outputs of all of the sonobuoy receivers were calibrated as a function of modulation frequency before the voyage, and DIFAR outputs from each of the 2902i and G39WSBe were connected to an instrument input of the UFX. The instrument inputs of the UFX (analog inputs 9-12) have a peak-peak voltage range of 80 V with digitally controlled gain that can be set between 10-65 dB, and this setting was noted in the Sonobuoy Deployment Log (see below) in order to measure received sound-pressure levels accurately. The digitised signals from the UFX were saved as 16-bit WAV files with 48 kHz sample rate using passive acoustic monitoring software Pamguard. Directional calibration The magnetic compass in each sonobuoy was calibrated/validated upon deployment as described by Miller et al. (2015, 2016). Calibration procedure involved measuring the mean bearing error and standard deviation of errors between the GPS-derived bearing from the sonobuoy to the ship and the magnetic bearing to the ship noise detected by the sonobuoy. 15-30 bearings were used for each calibration as the ship steamed directly away from the deployment location. Intensity calibration Obtaining calibrated intensity measurements from sonobuoys not only requires knowledge of the sensitivity of the hydrophone, but also the calibration parameters of the radio transmitter and radio receiver. Throughout the voyage, a hydrophone sensitivity of -122 dB re 1 V/µPa was applied to recordings via the Hydrophone Array Manager in PAMGuard. This value is defined in the DIFAR specification as the reference intensity at 100 Hz that will generate a frequency deviation of 25 kHz (Maranda 2001), thus the specification combines the hydrophone sensitivity and transmitter calibration. In line with manufacturers specifications, the WiNRADiO G39 WSB and 2902i both had a measured voltage response of approximately 1 V-peak–peak (approximately -3 dB) at 25 kHz frequency deviation (Miller et al. 2014), and this can be subtracted from the hydrophone sensitivity to yield an total combined factor of 125 dB re 1 V/µPa. These calibration settings, along with the shaped filter response provided by Greene et al. (2004) make it possible to obtain calibrated pressure amplitude from the recorded WAV audio files. Sonobuoy deployment metadata (Sonobuoy deployment log) This spreadsheet contains metadata on the deployment of sonobuoys deployed during the 2013 Antarctic Blue Whale Voyage. The first row contains column headers, while each subsequent row contains deployment information for a single sonobuoy. Information contained in each column are: buoyID: Buoy ID number is the sequential number of the buoy starting at 1 for the first buoy of the trip. startDate: Date (UTC) at the start of the sonobuoy deployment (YYYY-MM-DD) startTime: Time (UTC) at the start of the sonobuoy deployment (HH:MM:SS) 2 digit hour with 24 hour clock and leading zero. stopDate: Date (UTC) at the end of the sonobuoy deployment (YYYY-MM-DD). While the recording is in progress this should be 1,2 4 or 8 hours after the startTime based on sonobuoy setting. stopTime: Time (UTC) at the end of the sonobuoy deployment (HH:MM:SS). While the recording is in progress this should be 1,2 4 or 8 hours after the startTime based on the sonobuoy setting. lat: Latitude of deployment in decimal degrees. Southern hemisphere latitudes should be negative. long: Longitude of deployment in decimal degrees. Western hemisphere longitudes should be negative. alt: Depth of the sonobuoy deployment in metres. For DIFAR sonobuoys either 30, 120 or 300. recordingChannel: This is the channel number within the recorded wav-file that contains audio from this buoy as would be reported by Matlab. Channel numbers start at 1 (1-indexed) so usually this will be 1, 2 or 3. magVariation: The magnetic variation in degrees. Positive declination is East, negative is West. At the start of a recording this will be entered from a chart. As the recording progresses, this should be updated by measuring the bearing to the vessel. sonobuoyType: The an/ssq designation for the sonobuoy. Usually 53B, 53D, 53F, HIDAR, 57A/B, or 36Q. receiver: The type and serial number of the calibrated radio receiver (WinRadio) used to receive the VHF signal. (wr15725, wr17274, wr15274, or wr15273) preamp: The (unitless) gain in dB of any preamplifier (including the instrument preamp from the Fireface UFX). Usually 10 or 20 dB. adc: The analog-to-digital converter (adc) used to digitize the audio. This is the sound card name and gain. All data were recorded on an RME Fireface UFX, so Ufx10 would be the RME Fireface UFX with a gain of 10 dB. vhfFreq: The VHF channel number used to receive the sonobuoys. Sonobuoys have 99 pre-set VHF channels between Real-time monitoring and analysis (Acoustic event log) During the 2012 Blue Whale Voyages Acousticians noted all whale calls and other acoustic events that were detected during real-time monitoring in a written Sonobuoy Event Log. Additionally, the acoustic tracking software, difarBSM, stored processed bearings from acoustic events and cross bearings in tab delimited text files. Each event was assigned a classification by the acoustician, and events for each classification were stored in separate text files. The first row in each file contains the column headers, and the content of each column is as follows: buoyID: Buoy ID number is the number of the sonobuoy on which this event was detected. This can be used as a foreign key to link to the sonobuoy deployment log. timeStamp_matlabDatenum: Date and time (UTC) at the start of the event represented as a Matlab datenum (i.e. number of days since Jan 0 0000). Latitude: Latitude of the sonobuoy deployment in decimal degrees. Southern hemisphere latitudes should be negative. Longitude: Longitude of sonobuoy deployment in decimal degrees. Western hemisphere longitudes should be negative. Altitude: Depth of the sonobuoy deployment in metres. For DIFAR sonobuoys either 30, 120 or 300. magneticVariation_degrees: The estimated magnetic variation of the sonobuoy in degrees at the time of the event. Positive declination is East, negative is West. At the start of a recording this will be entered from a chart. As the recording progresses, this should be updated by measuring the bearing to the vessel. bearing_degreesMagnetic: Magnetic bearing in degrees from the sonobuoy to the acoustic event. Magnetic bearings were selected by the acoustician by choosing a single point on the bearing-frequency surface (AKA DIFARGram) produced by the analysis software difarBSM. frequency_Hz: The frequency in Hz of the magnetic bearing that the acoustician selected from the bearing-frequency surface (DIFARGram). logDifarPower: The base 10 logarithm of the height of the point on the DIFARGram receiveLevel_dB: This column contains an estimate of the The RMS receive level (dB SPL re 1 micro Pa) of the event. Received levels were estimated by applying a correction for the shaped sonobuoy frequency response, the receiver’s frequency response, and were calculated over only the frequency band specified in each classification (see below). soundType: soundType is the classification assigned to the event by the acoustician. Aural and visual monitoring of audio and spectrograms from each sonobuoy was conducted for each sonobuoy deployment. Detections from marine mammals, and other sources and were detected and classified manually, and their time and frequency bounds were marked on the PAMGuard spectrogram. Parameters for monitoring and recording, were stored within the PAMGuard database and as stand-alone Pamguard Settings Files (PSF). During the voyage there were detections of pygmy blue whale song, and blue whale 'D-call' vocalisations. During the dedicated blue whale voyages the course of the ship was diverted to follow bearings to vocalising blue whales. Whale tracking log (Written Whale Acoustic Tracking Log - Tangaroa 2015.pdf) During the 2012 Blue Whale Voyages, noted all whale calls and other acoustic events that were detected during real-time monitoring in a Sonobuoy Event Log. A written summary of the event log was recorded during data collection at approximately 15 minute intervals, and this summary comprises the Whale Tracking Log. - Tracking Log. - Entries in the written Sonobuoy Tracking Log (on the bench in the acoustics workstation) also include total number of different whales heard in that 15 minute interval. - If multiple whales/groups were detected, then the acoustician on-duty, in consultation with the lead acoustician and/or voyage management designateded one of the whales the 'target' whale, and attempted to encounter this target first. - When targeting a whale/group, the acoustician on-duty continued to track all other whales/groups in the area as these tracked whales/groups may become the next target after obtaining concluding with the current target. Date: (UTC) written only at top of datasheet Time: (UTC) on the hour, 15 past, half past, and 15 to. Track: Unique identifier for each whale/group tracked in the past 15 minutes. Each track will have: Position: Either an average bearing from a sonobuoy (eg 220 degrees from SB18) or a Lat/Lon from the most recent triangulation Notes: What is the vessel action with respect to this tracked whale/group? (eg. Is this the current or previous 'target'? Are we presently photographing this whale? Did we finish photographing the whale?) Has the whale gone silent? Has this track crossed paths with another?

During the 2013 Antarctic Blue Whale Voyage Acousticians noted all whale calls and other acoustic events that were detected during real-time monitoring in a Sonobuoy Event Log. A written summary of the event log was recorded during data collection at approximately 15 minute intervals, and this summary comprises the Whale Tracking Log. - The acoustician on-duty recorded the average bearings or locations of each calling whale/group every 15 minutes in the written Whale Tracking Log. - Entries in the written Sonobuoy Tracking Log (on the bench in the acoustics workstation) also include total number of different whales heard in that 15 minute interval. - If multiple whales/groups were detected, then the acoustician on-duty, in consultation with the lead acoustician and/or voyage management designateded one of the whales the 'target' whale, and attempted to encounter this target first. - When targeting a whale/group, the acoustician on-duty continued to track all other whales/groups in the area as these tracked whales/groups may become the next target after obtaining concluding with the current target. Date: (UTC) written only at top of datasheet Time: (UTC) on the hour, 15 past, half past, and 15 to. Track: Unique identifier for each whale/group tracked in the past 15 minutes. Each track will have: Location: Either an average bearing from a sonobuoy (eg 220 degrees from SB18) or a Lat/Lon from the most recent triangulation Notes: What is the vessel action with respect to this tracked whale/group? (eg. Is this the current or previous 'target'? Are we presently photographing this whale? Did we finish photographing the whale?) Has the whale gone silent? Has this track crossed paths with another?

This annotated library contains both a data set and a data product. The data set contains a sub-sample of underwater recordings made around Antarctica from 2005-2017. These recordings were curated and sub-sampled from a variety of national and academic recording campaigns. Recordings were made using a variety of different instruments, and sub-samples span 11 different combinations of site and year. Spatial coverage of the recordings includes sites in the Western Antarctic Peninsula, Atlantic, Indian, and Pacific sectors. Temporal coverage of recordings covers a representative sample throughout each recording year for the years of 2005, 2013, 2014, 2015, and 2017. The focus is on low-frequency sounds of blue and fin whales, so curated recordings have been downsampled to sample rates of either 250, 500, 1000 or 2000 Hz. Recordings are all in 16-bit wav format. The file name of each wav file contains a timestamp with the date and time of the start of that file. Recordings are contained in the /wav/ subfolder for each site-year (e.g. Casey2014/wav). The data product is in the form of annotations that describe the times within each WAV file that contain detections of blue and fin whale sounds. Each annotations are stored as a row in a tab-separated text file (with descriptive column headers), and each text file describes a particular type of sound. These annotation text files are formatted as Selection Tables that can be directly imported into the software program Raven Pro 1.5 (Cornell Bioacoustics Laboratory). Full description of the details of the creation and use of this dataset are described in the draft manuscript contained in the documentation folder.

This dataset contains long-term underwater acoustic recordings made under Australian Antarctic Science Projects 4101 and 4102, and the International Whaling Commission’s Southern Ocean Research Partnership (IWC-SORP) Southern Ocean Hydrophone Network (SOHN). Calibrated measurements of sound pressure were made at several sites across several years using custom moored acoustic recorders (MARs) designed and manufactured by the Science Technical Support group of the Australian Antarctic Division. These moored acoustic recorders were designed to operate for year-long, deep-water, Antarctic deployments. Each moored acoustic recorder included a factory calibrated HTI 90-U hydrophone and workshop-calibrated frontend electronics (hydrophone preamplifier, bandpass filter, and analog-digital converter), and used solid state digital storage (SDHC) to reduce power consumption and mechanical self-noise (e.g. from hard-drives with motors and rotating disks). Electronics were placed in a glass instrumentation sphere rated to a depth of 6000 m, and the sphere was attached to a short mooring with nylon straps to decouple recorder and hydrophone from sea-bed. The hydrophone was mounted above the glass sphere with elastic connections to the mooring frame to reduce mechanical self-noise from movement of the hydrophone. The target noise floor of each recorder was below that expected for a quiet ocean at sea state zero. The analog-digital converter, based on an AD7683B chip, provides 100 dB of spurious free dynamic range, but a total signal-to-noise and distortion of 86 dB which yields 14 effective bits of dynamic range at a 1 kHz input frequency. The data for each recording site comprise a folder of 16-bit WAV audio files recorded at a nominal sample rate of 12 kHz. The names of each WAV file correspond to a deployment code followed by the start time (in UTC) of the file as determined by the microprocessor’s real-time clock e.g. 201_2013-12-25_13-00-00.wav would correspond to a wav file with deployment code 201 that starts at 1 pm on December 25th 2013 (UTC). Recording locations were chosen to correspond to sites used during AAS Project 2683. These sites were along the resupply routes for Australia’s Antarctic stations, and typically there was only one opportunity to recover and redeploy MARs each year.

Hydroacoustics data obtained from Australian Antarctic Division voyages from 1993 to 2004. Voyages were made to various locations within the Southern Ocean. Data are stored on 14 hard disks, 1 CD-R and 1 DVD-R for archiving in a secure storage area. A catalogue describing what data are held on each media is available for download from the provided URL. The hard disks in the archive box are labelled as 'Status 1'. These data were collected under several ASAC projects - ASAC 357 (Hydroacoustic Determination of the Abundance and Distribution of Krill in the Region of Prydz Bay, Antarctica) and ASAC 1250 (Krill flux, acoustic methodology and penguin foraging - an integrated study) - ASAC_357 and ASAC_1250. 2008-11-07 Note - all Australian Antarctic Division hydroacoustic data have now been collated on the AAD Storage Area Network (SAN). This digital collection supersedes the collection of hard disks, and comprises (as of now) the sum total of all AAD hydroacoustic data. Ideally as more hydroacoustic data are collected by AAD vessels, they will be added to the SAN. See the metadata record entitled "Hydroacoustic data collected from Southern Ocean Cruises by the Australian Antarctic Division" for more information.

The Davis Aerodrome Project (DAP) collected a range of environmental survey data over several field seasons to support a comprehensive environmental assessment of the proposed aerodrome. This data includes flora, fauna, soils, lake ecosystem, nearshore, marine, air quality and meteorological information which has been collected by a number of different methods, and extends across the current Davis Station, proposed aerodrome and supporting infrastructure footprint (Ridge Site), previous sites considered for the aerodrome (Heidemann Valley, Adams Flat), as well as locations across the Vestfold Hills away from any of the proposed developments. This dataset contains long-term underwater acoustic recordings made for the Australian Antarctic Division’s Davis Aerodrome Project 5097 environmental assessments. Calibrated measurements of sound pressure were made at two sites in the vicinity of Davis Research station (approx. 5km west of the station and one in Long Fjord to the north of station). The attached data was downloaded from the instrument deployed west of Davis Station. Data was recorded over 7 months using a custom moored Autonomous Multichannel Acoustic Recorder (AMAR G4) designed and manufactured by JASCO Applied Science following specifications provided by the Australian Antarctic Division. These moored acoustic recorders were designed to operate for year-long, near shore, Antarctic deployments. The moorings were deployed through the ice during the 2021 winter and one retrieved during the 2021/22 summer when the seaice was clear of the surface. The Autonomous Multichannel Acoustic Recorder is a fully autonomous underwater sound and data recorder. The acoustic recorder included a factory calibrated M36-100 hydrophone, data acquisition electronics and solid state digital storage (SDHC) to reduce power consumption and mechanical self-noise (e.g. from hard-drives with motors and rotating disks). Batteries, SDHC cards and electronics were placed in watertight pressure sealed PVC housing rated to a depth of 250 m. The moorings were secured to the seafloor by weights and suspended up into the water column by a string of floats attached to the top of the structure to separate the recorder and hydrophone from sea-bed. The hydrophone was securely mounted to the base of the AMAR housing. All connections between mooring components where taped with protective coverings to reduce mechanical self-noise from movement of the structure. The target noise floor of each recorder was below that expected for a quiet ocean at sea state zero. The data for each recording site comprise folders of 24-bit WAV audio files recorded on a duty cycle with two different sample rates. The duty cycle recorded for 60 s at a sample-rate of 512 kHz, followed immediately by a 580 s at a sample-rate of 32 kHz, and then 280 s off before repeating. The names of each WAV file correspond to instrument serial number followed by the start time (in UTC) of the file as determined by the AMAR’s real-time clock e.g. AMAR897.20210722T061621Z.wav would correspond to a wav from AMAR serial number 897 that starts at 06:16:21 on 22 July 2021 (UTC).

This dataset contains acoustic recordings from Directional Frequency Analysis and Recording (DIFAR) sonobuoys that were deployed from 22 January – 18 March 2017 during the Antarctic Circumnavigation Expedition. During the 52 days at sea 301 sonobuoys were deployed yielding 492 hours of acoustic recordings. Two models of sonobuoys were used during the voyage: 1 was a bespoke reusable DIFAR buoy based on a sensor and radio from an AN/SSQ-53F sonobuoy (Ultra Electronics: SonobuoyTechSystems, USA) and 300 were re-lifed AN/SSQ-955-HIDAR (deployed in DIFAR compatibility mode; Ultra Electronics Sonar Systems, UK). Two dedicated acousticians monitored round-the-clock for blue, fin, sperm, humpback, minke, killer, and sei whales, and crabeater, leopard, Ross, and weddell seals and in all weather conditions. During ACE, we conducted a broad-scale, passing-mode passive acoustic survey for marine mammals in the Southern Ocean. Listening stations were conducted by deploying SSQ955 HIDAR sonobuoys in DIFAR (standard) mode to monitor for and measure bearings to vocalising whales while the ship was underway (Gedamke and Robinson 2010, Miller et al. 2015). During transit, listening stations were conducted every 30-60 nmi in water depths greater than 200 m. Sonobuoys were occasionally deployed with spacing less than 30 nmi in an attempt to more precisely determine spatial extent and vocal characteristics of calls that were believed to be coming from animals relatively close to the ship’s track. During terrestrial stopovers and marine science stations, sonobuoys were deployed approximately 2-4 nmi prior to stopping in order to attempt to monitor them for the full six-hour duration of their operational life. This distance ensured good radio signal while minimising acoustic interference from the vessel. The sampling regime was chosen to balance spatial resolution with the finite number of sonobuoys available for this study. Instrumentation, software, and data collection At each listening station, a HIDAR sonobuoy was deployed with the hydrophone set to a depth of 140 m. Sonobuoys transmitted underwater acoustic signals from the hydrophone and directional sensors back to the ship via a VHF radio transmitter. Radio signals from the sonobuoy were received using an omnidirectional VHF antenna (PCTel Inc. MFB1443; 3 dB gain tuned to 144 MHz centre frequency) and a Yagi antenna (Broadband Propagation Pty Ltd, Sydney Australia) mounted on the top of the helicopter control room at a height of 23.0 m. The antennas were each directly connected to a WiNRADiO G39WSBe sonobuoy receiver via low-loss LMR400 coaxial cable. The radio reception range on the Yagi antenna was similar to previous Antarctic voyages, and was adequate for monitoring and localisation typically out to a range of 12-14 nmi, provided that the direction to the sonobuoy was close (i.e. within around 30o) to the main axis of the antenna. The radio reception on the omnidirectional antenna typically provided 5-8 nmi of omnidirectional reception from sonobuoys. At transit speed (14-15 knots), the Yagi antenna provided about 55 minutes of acoustic recording time per sonobuoy Using both antennas together were able obtain radio reception for up to six hours (i.e. the maximum life of a 955 sonobuoy) when sonobuoys were deployed within 5 nmi of a marine science station. Received signals were digitised via the instrument inputs of a Fireface UFX sound board (RME Fireface; RME Inc.). Digitised signals were recorded on a personal computer as 48 kHz 24-bit WAV audio files using the software program PAMGuard (Gillespie et al. 2008). Data from both the Yagi and Omnidirectional antenna were recorded simultaneously as WAV audio channels 0 (left) and 1 (right). Each recorded WAV file therefore contains a substantial amount of duplication since both antennas and receivers were usually receiving the same signals from the same sonobuoy. Directional calibration The magnetic compass in each sonobuoy was calibrated/validated upon deployment as described by Miller et al. (2015, 2016). Calibration procedure involved measuring the mean bearing error and standard deviation of errors between the GPS-derived bearing from the sonobuoy to the ship and the magnetic bearing to the ship noise detected by the sonobuoy. 15-20 bearings were used for each calibration as the ship steamed directly away from the deployment location. Intensity calibration Obtaining calibrated intensity measurements from sonobuoys not only requires knowledge of the sensitivity of the hydrophone, but also the calibration parameters of the radio transmitter and radio receiver. Throughout the voyage, a hydrophone sensitivity of -122 dB re 1 V/micro Pa was applied to recordings via the Hydrophone Array Manager in PAMGuard. This value is defined in the DIFAR specification as the reference intensity at 100 Hz that will generate a frequency deviation of 25 kHz (Maranda 2001), thus the specification combines the hydrophone sensitivity and transmitter calibration. In line with manufacturers specifications, the WiNRADiO G39 WSB had a measured voltage response of 1 V-peak–peak (approximately -3 dB) at 25 kHz frequency deviation (Miller et al. 2014), and this was subtracted from the hydrophone sensitivity to yield an total combined factor of 125 dB re 1 V/µPa. The gain of the instrument input on the Fireface UFX was set to 20 dB, yielding a maximum voltage input voltage range of 8.36 V peak–peak. These calibration settings, along with the shaped filter response provided by Greene et al. (2004) make it possible to obtain calibrated pressure amplitude from the recorded WAV audio files. Sonobuoy deployment metadata The PAMGuard DIFAR Module (Miller et al. 2016) was used to record the sonobuoy deployment metadata such as location, sonobuoy deployment number, and audio channel in the HydrophoneStreamers table of the PAMGuard database (PamguardBlueWhale-2015-02-03.mdb). A written sonobuoy deployment log (Sonobuoy deployment logbook - 2015 Tangaroa.pdf) was also kept during the voyage, and this includes additional notes and additional information not included in the PAMGuard Database such as sonobuoy type, and sonobuoy end-time. Real-time monitoring and analysis (Acoustic event log) Aural and visual monitoring of audio and spectrograms from each sonobuoy was conducted using PAMGuard for at least an hour at each listening station. Two different spectrograms were typically viewed, one for low-frequency sounds with the following parameters: 250 Hz sample rate; 256 sample FFT; 32 sample advance between time slices. The other spectrogram was used to view mid-frequency sounds with the following parameters: 8000 Hz sample rate; 1024 sample FFT; 128 sample advance between time slices. Monitoring was conducted in real-time as data were being acquired, and the intensity scale of the spectrogram was adjusted by the operator to suit the ambient noise conditions. When detections from marine mammals, ice, and other sources were detected, they were classified manually, and their time and frequency bounds marked on the spectrogram. The PAMGuard DIFAR module (Miller, Calderan, et al. 2016) was then used to measure the direction of arrival and intensity of suitable calls such as tonal, frequency-modulated, and pulsed calls of baleen whales, whistles and trills from pinniped, and some whistles from toothed whales. Echolocation clicks from sperm whales (Physeter macrocephalus) were noted in the PAMGuard UserInput (free form notes stored in the PAMGuard Sqlite database), but could not be localised with the DIFAR module due to limitations inherent in directional sensors in the sonobuoy. Detection, bearing, and intensity measurements were saved both within a PAMGuard binary file and within the DIFAR_Localisation table of the PAMGuard database. In addition to PAMGuard binary files and audio files, the PAMGuard settings and metadata were saved to the PAMGuard Sqlite database. During Leg 3, some experimental trials were conducted with sonobuoys deployed in pairs with one hydrophone set to a depth of 140m and the other set to either 300m or 30m (the other two depth options available in the sonobuoy settings). The aim of these experiments was to investigate any differences with received level and the depth of the receiver. Recordings collected over a range of received levels as the vessel headed away from vocalising whales can also allow estimates of bearing accuracy for weak calls (by comparing bearings to the same call from different buoys) and the relative detection probability for calls under different noise conditions (by using the signals from each buoy in a similar way to independent observer experiments). References Greene, C.R.J. et al., 2004. Directional frequency and recording ( DIFAR ) sensors in seafloor recorders to locate calling bowhead whales during their fall migration. Journal of the Acoustical Society of America, 116(2), pp.799–813. Maranda, B.H., 2001. Calibration Factors for DIFAR Processing, Miller, B.S. et al., 2014. Accuracy and precision of DIFAR localisation systems: Calibrations and comparative measurements from three SORP voyages. Submitted to the Scientific Committee 65b of the International Whaling Commission, Bled, Slovenia. SC/65b/SH08, p.14. Miller, B.S. et al., 2016. Software for real-time localization of baleen whale calls using directional sonobuoys: A case study on Antarctic blue whales. The Journal of the Acoustical Society of America, 139(3), p.EL83-EL89. Available at: http://scitation.aip.org/content/asa/journal/jasa/139/3/10.1121/1.4943627. Miller, B.S. et al., 2015. Validating the reliability of passive acoustic localisation: a novel method for encountering rare and remote Antarctic blue whales. Endangered Species Research, 26(3), pp.257–269. Available at: http://www.int-res.com/abstracts/esr/v26/n3/p257-269/.

The sonobuoy deployment log is a csv file that contains metadata on the deployment of sonobuoys deployed during the 2013 Antarctic Blue Whale Voyage. The first row contains column headers, while each subsequent row contains deployment information for a single sonobuoy. Data that were recorded during each sonobuoy deployment are: buoyID: Buoy ID number is the sequential number of the buoy starting at 1 for the first buoy of the trip. startDate: Date (UTC) at the start of the sonobuoy deployment (YYYY-MM-DD) startTime: Time (UTC) at the start of the sonobuoy deployment (HH:MM:SS) 2 digit hour with 24 hour clock and leading zero. stopDate: Date (UTC) at the end of the sonobuoy deployment (YYYY-MM-DD). While the recording is in progress this should be 1,2 4 or 8 hours after the startTime based on sonobuoy setting. stopTime: Time (UTC) at the end of the sonobuoy deployment (HH:MM:SS). While the recording is in progress this should be 1,2 4 or 8 hours after the startTime based on the sonobuoy setting. lat: Latitude of deployment in decimal degrees. Southern hemisphere latitudes should be negative. long: Longitude of deployment in decimal degrees. Western hemisphere longitudes should be negative. alt: Depth of the sonobuoy deployment in metres. For DIFAR sonobuoys either 30, 120 or 300. recordingChannel: This is the channel number within the recorded wav-file that contains audio from this buoy as would be reported by Matlab. Channel numbers start at 1 (1-indexed) so usually this will be 1, 2 or 3. magVariation: The magnetic variation in degrees. Positive declination is East, negative is West. At the start of a recording this will be entered from a chart. As the recording progresses, this should be updated by measuring the bearing to the vessel. sonobuoyType: The an/ssq designation for the sonobuoy. Usually 53B, 53D, 53F, HIDAR, 57A/B, or 36Q. receiver: The type and serial number of the calibrated radio receiver (WinRadio) used to receive the VHF signal. (wr15725, wr17274, wr15274, or wr15273) preamp: The (unitless) gain in dB of any preamplifier (including the instrument preamp from the Fireface UFX). Usually 10 or 20 dB. adc: The analog-to-digital converter (adc) used to digitize the audio. This is the sound card name and gain. All data were recorded on an RME Fireface UFX, so Ufx10 would be the RME Fireface UFX with a gain of 10 dB. vhfFreq: The VHF channel number used to receive the sonobuoys. Sonobuoys have 99 pre-set VHF channels between