Multibeam, echosounder and gravity cores data of the headwall area in the Sahara Slide Complex

The bulk of multibeam bathymetric data were acquired during RV Maria S. Merian cruises MSM11/2 (Bickert et al., 2009), MSM82/2 (Krastel et al., 2019a) and MSM87 (Krastel et al., 2019b) with hull-mounted Kongsberg Simrad systems EM120 (MSM11/2) and EM122 (MSM82/2 and MSM87). The nominal sonar frequency is 12 kHz. The angular coverage is up to 150°, and each angular beam accuracy was 2° by 2°. Kongsberg Seapath system provides the combined motion, position and time data, which are transmitted to the Processing Unit (PU) of the multibeam echosounder to achieve real-time motion compensation in pitch, roll and yaw. All raw data were processed with MB-System software (Caress and Chayes, 2017: https://www.mbari.org/products/research-software/mb-system/). Sound velocities were measured with a Conductivity, Temperature, Depth (CTD) probe during MSM 82/2 and an expendable sound velocimeter during MSM87. The multibeam data in cruise MSM82/2 were collected from the 11th to 13th of May in 2019 in the headwall area of the Sahara Slide Complex. Only two sound velocities were measured on the 11th and 12th of May, and we applied the measured sound velocities to data from these two days. In the mean time, the measured sound velocity on 12th of May was also applied to data collected on 13th of May. For MSM11/2, sound velocities were adjusted using the mbvelocity tool implemented in the MB-System software. The multibeam bathymetric data were gridded by using the splines with tension algorithm to a final grid with 150 m cell spacing in lateral direction. Echosounder data were acquired during several cruises with RV Maria S. Merian (MSM11/2, MSM82/2, MSM87). The high-resolution parametric ATLAS Parasound System DS3 (Atlas Hydrographic®) is a hull-mounted parametric echo sounder; the secondary low frequency (SLF) was set to 4 kHz through our cruises. The opening angle of the system is 4.5°. The system allows imaging of the uppermost 50-100 m of sediment at a sub-meter vertical resolution. The echogram sections were filtered with a wide band pass filter to improve the signal-to-noise ratio. The data were analyzed and interpreted in IHS Kingdom®. Gravity cores were acquired with a 5 m-long standard gravity corer during RV Maria S. Merian Cruise MSM82/2 (cores MSM82/2-34, MSM82/2-35 and MSM82/2-36). They were studied by color analysis, photography and sedimentological description. […]

大部分多波束测深数据（multibeam bathymetric data）由“玛丽亚·S·梅里安号”科研考察船（RV Maria S. Merian）的MSM11/2（Bickert等，2009）、MSM82/2（Krastel等，2019a）及MSM87（Krastel等，2019b）航次采集，搭载船底安装的Kongsberg Simrad EM120（用于MSM11/2航次）与EM122（用于MSM82/2、MSM87航次）系统。该系统的标称声呐频率为12 kHz，波束覆盖角度可达150°，单波束角精度为2°×2°。Kongsberg Seapath系统可提供组合运动、位置与时间数据，并将其传输至多波束回声测深仪（multibeam echosounder）的处理单元（Processing Unit, PU），以实现纵倾、横滚与偏航的实时运动补偿。所有原始数据均通过MB-System软件（Caress与Chayes，2017：https://www.mbari.org/products/research-software/mb-system/）完成处理。声速测量方面，MSM82/2航次采用温盐深探头（Conductivity, Temperature, Depth, CTD）进行测量，MSM87航次则使用抛弃式声速仪（expendable sound velocimeter）。MSM82/2航次的多波束测深数据采集于2019年5月11日至13日的撒哈拉滑塌复合体（Sahara Slide Complex）崖壁区域，本次航次仅在5月11日与12日完成声速测量，我们将这两日测得的声速应用于对应日期的数据；同时将5月12日测得的声速应用于5月13日采集的数据。对于MSM11/2航次，声速通过MB-System软件内置的mbvelocity工具进行校正。多波束测深数据通过带张力样条算法（splines with tension algorithm）网格化为横向格距150 m的最终网格。回声测深数据由“玛丽亚·S·梅里安号”科研考察船的多轮航次采集（涵盖MSM11/2、MSM82/2及MSM87航次）。高分辨率参数型ATLAS Parasound System DS3（Atlas Hydrographic®）为船载参数式回声测深仪，本次航次中其二阶低频（Secondary Low Frequency, SLF）设置为4 kHz。该系统开角为4.5°，可对表层50~100 m的沉积物实现亚米级垂直分辨率成像。回声剖面图（echogram sections）经宽带通滤波器滤波以提升信噪比（signal-to-noise ratio）。数据通过IHS Kingdom®软件完成分析与解译。MSM82/2航次中，使用5米长的标准重力取芯器采集了重力岩心（gravity cores），编号为MSM82/2-34、MSM82/2-35及MSM82/2-36。对上述岩心开展了色度分析、摄影及沉积学描述。[…]