Passive acoustic recordings from sonobuoys deployed during the NZ-Aus Antarctic Ecosystems Voyage 2015

This dataset contains acoustic recordings from Directional Frequency Analysis and Recording (DIFAR) sonobuoys that were deployed throughout the 2015 NZ-Aus Antarctic Ecosystems Voyage. During the 42 day voyage 310 sonobuoys were deployed yielding 520 hours of acoustic recordings. Two models of sonobuoys were used during the voyage: 2 were AN/SSQ-53F (Ultra Electronics: SonobuoyTechSystems, USA) and 308 were re-lifed AN/SSQ-955-HIDAR (deployed in DIFAR compatibility mode; Ultra Electronics Sonar Systems, UK). A total team of four dedicated acousticians monitored round-the-clock for blue whales and in all weather conditions. After deployment, sonobuoys sent acoustic and directional data 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 pre-amplifier (Minicircuits Inc. ZX60-33LN-S+) mounted on the mast of the ship at a height of 21 m. The preamplifier was connected to a power splitter via LMR400 cable and signals were received with two WiNRaDiO G39WSBe sonobuoy receivers. The radio signal from sonobuoys was adequate for monitoring and localization out to a typical range of 12-15 nmi. Received signals were digitised via the instrument inputs of a Fireface UFX sound board (RME Fireface; RME Inc.) with a gain set to 20 dB (8.396 V peak-peak voltage limits). Digitised signals were recorded on a personal computer as two-channel 48 kHz 24-bit WAV audio files using the software program PAMGuard (Gillespie et al. 2008). Directional calibrationThe 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 calibrationObtaining 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 metadataThe 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 for each sonobuoy deployment. 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 typically 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. Detections from marine mammals, ice, and other sources and were detected and classified manually, and their time and frequency bounds were marked on the PAMGuard spectrogram. The PAMGuard DIFAR module (Miller et al. 2016) was then used to measure the direction of arrival and intensity of suitable calls from a variety of species such as tonal, frequency-modulated, and pulsed calls of baleen whales; and also some whistles from toothed whales. Echolocation clicks from sperm whales and any other short broadband sounds were noted in the PAMGuard UserInput (free form notes stored in the PAMGuard Microsoft Access database), but were not able to be localised with the DIFAR module due to limitations inherent in directional sensors in the sonobuoy. Each detection, bearing, and intensity measurement were saved within PAMGuard binaryStorage files in addition to the DIFAR_Localisation table of the PAMGuard database. In addition to PAMGuard binary files and audio files, the PAMGuard settings and metadata were saved inside the PAMGuard Sqlite database. Parameters for monitoring, recording, directional analysis, and other PAMGuard modules were stored within the PAMGuard database and as stand-alone PAMGuard Settings Files (PSF).In addition to recording of Antarctic blue whale song, New Zealand type blue whale song, and blue whale 'D-call' vocalisations, these recordings also contain vocalisations from fin whales, humpback whales, killer whales, sperm whales, as well as low frequency sounds from Antarctic sea ice.Whale tracking log (Written Whale Acoustic Tracking Log - Tangaroa 2015.pdf)During the 2015 Voyage Acousticians also created a written summary of the event log at irregular intervals, typically between 30-60 minutes and this summary comprises the Whale Tracking Log. The acoustician on-duty recorded the average bearings or locations of each calling whale/group in the written Whale Tracking Log when the situation regarding the relative position of tracked whale groups was deemed to have changed. Entries in the written Sonobuoy Tracking Log (on the bench in the acoustics workstation) included the location of different whale groups and total number of different whale groups heard during that time interval.ReferencesGreene, 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/.Raw Audio Files: DS05_Sonobuoy_audioSonobuoy deployment log: DS07_Sonobuoy_deployment_logAcoustic event log: DS08_Acoustic_event_logWhale tracking log: DS09_Whale_tracking_log

本数据集收录了2015年新澳南极生态系统科考航次中部署的定向频率分析与记录（Directional Frequency Analysis and Recording, DIFAR）声呐浮标（sonobuoy）的声学录音数据。本次航次为期42天，共部署310个声呐浮标，累计获得520小时的声学录音。航次中使用了两款声呐浮标：2个为AN/SSQ-53F型（美国Ultra Electronics SonobuoyTechSystems公司），剩余308个为翻新的AN/SSQ-955-HIDAR型（以DIFAR兼容模式部署；英国Ultra Electronics Sonar Systems公司）。

本次科考由4名专职声学研究员组成团队，全天候、全天气条件下开展蓝鲸声学监测。声呐浮标部署后，通过甚高频（Very High Frequency, VHF）无线电发射机将声学与定向数据回传至科考船。浮标发射的无线电信号由安装于船桅21米高度处的全向VHF天线（PCTel公司 MFB1443型，中心频率调谐至144 MHz，增益3 dB）与前置放大器（Minicircuits公司 ZX60-33LN-S+型）接收。前置放大器通过LMR400线缆连接至功率分配器，随后由两台WiNRaDiO G39WSBe型声呐浮标接收机采集信号。该无线电链路的有效监测与定位距离可达12~15海里（nautical mile, nmi）。

接收信号通过Fireface UFX声卡（RME Fireface；德国RME公司）的仪器输入接口进行数字化，增益设置为20 dB（峰值电压范围8.396 Vpp）。数字化后的信号通过PAMGuard软件（Gillespie等，2008）存储于个人计算机中，格式为双通道48 kHz、24位的WAV音频文件。

### 定向校准
每台声呐浮标的磁罗盘均在部署时完成校准与有效性验证，校准流程参照Miller等（2015、2016）的方法。校准过程中，需测量浮标基于GPS获取的指向船艇的方位角，与浮标探测到的船艇噪声对应的磁方位角之间的平均方位误差及误差标准差。当科考船直接驶离部署点位时，每次校准需采集15~20组方位数据。

### 强度校准
从声呐浮标获取校准后的强度测量值，不仅需要知晓水听器（hydrophone）的灵敏度，还需掌握无线电发射机与接收机的校准参数。本次航次中，通过PAMGuard软件的水听器阵列管理器，将录音的水听器灵敏度设置为-122 dB re 1 V/μPa。该数值由DIFAR技术规范定义：当频率偏移为25 kHz时，100 Hz处的参考声强（Maranda, 2001），因此该参数整合了水听器灵敏度与发射机校准结果。根据厂商技术规范，WiNRADiO G39 WSB型接收机在25 kHz频率偏移下的电压响应为1 Vpp（约-3 dB），将该值从水听器灵敏度中扣除后，得到总综合因子为125 dB re 1 V/μPa。Fireface UFX声卡的仪器输入增益设置为20 dB，对应的最大输入电压范围为8.36 Vpp。结合上述校准设置与Greene等（2004）提出的整形滤波响应，可从录制的WAV音频文件中获取校准后的声压幅值。

### 声呐浮标部署元数据
使用PAMGuard DIFAR模块（Miller等，2016）将声呐浮标部署元数据（包括部署位置、浮标编号、音频通道）存储于PAMGuard数据库的HydrophoneStreamers表中，数据库文件为PamguardBlueWhale-2015-02-03.mdb。航次期间同时保留了书面声呐浮标部署日志（Sonobuoy deployment logbook - 2015 Tangaroa.pdf），其中包含PAMGuard数据库未收录的补充说明与额外信息，例如浮标型号与浮标终止工作时间。

### 实时监测与分析（声学事件日志）
针对每一次声呐浮标部署，均对浮标采集的音频与语谱图开展听觉与可视化监测。通常同时查看两种语谱图：一种用于分析低频声音，参数设置为采样率250 Hz、快速傅里叶变换（Fast Fourier Transform, FFT）点数256、时间切片步进32个采样点；另一种用于分析中频声音，参数设置为采样率8000 Hz、FFT点数1024、时间切片步进128个采样点。监测通常在数据采集阶段实时进行，操作人员会根据环境噪声条件调整语谱图的强度标尺。对海洋哺乳动物、海冰及其他声源的信号开展人工检测与分类，并在PAMGuard生成的语谱图上标记其时间与频率范围。随后使用PAMGuard DIFAR模块（Miller等，2016）测量适配声源的到达方向与声强，这些声源包括须鲸的单音调、调频及脉冲式鸣唱，以及齿鲸的部分哨叫声。抹香鲸的回声定位咔哒声及其他短宽带脉冲声会被记录在PAMGuard UserInput字段中（存储于PAMGuard Microsoft Access数据库内的自由格式笔记），但由于声呐浮标定向传感器的固有局限，无法通过DIFAR模块完成定位。每一次检测结果、方位角与强度测量值，除存储于PAMGuard数据库的DIFAR_Localisation表外，同时保存于PAMGuard二进制存储文件中。除PAMGuard二进制文件与音频文件外，PAMGuard的软件设置与元数据存储于PAMGuard SQLite数据库中。监测、录音、定向分析及其他PAMGuard模块的参数，既存储于PAMGuard数据库，也导出为独立的PAMGuard设置文件（PSF格式）。

本数据集除收录南极蓝鲸鸣唱、新西兰型蓝鲸鸣唱及蓝鲸“D呼叫”发声外，还包含长须鲸、座头鲸、虎鲸、抹香鲸的发声，以及南极海冰产生的低频声学信号。

### 鲸鱼追踪日志（书面版：Whale Acoustic Tracking Log - Tangaroa 2015.pdf）
2015年航次期间，声学研究员每隔30~60分钟（间隔不固定）对事件日志进行书面汇总，形成鲸鱼追踪日志。当被追踪鲸群的相对位置发生变化时，当班声学研究员会在书面鲸鱼追踪日志中记录各鸣唱鲸群的平均方位角或位置。声学工作站台面上的书面声呐浮标追踪日志条目，需记录该时段内观测到的不同鲸群的位置与总数量。

### 参考文献
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/.

### 配套数据文件
- 原始音频文件：DS05_Sonobuoy_audio
- 声呐浮标部署日志：DS07_Sonobuoy_deployment_log
- 声学事件日志：DS08_Acoustic_event_log
- 鲸鱼追踪日志：DS09_Whale_tracking_log