Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Supplemental Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Particle size distribution (PSD) measurements were made in June 2019 at Station ALOHA (22.75°N, 158°W) in the North Pacific Subtropical Gyre aboard the R/V Kilo Moana (KM1910).  PDSs were measured using the Laser In Situ Scatterometer and Transmissometer 100X (Type B, Sequoia Scientific Inc., hereafter LISST) which uses laser diffraction in an approximately 100 ml sample volume to estimate the PSD via inversion into 32 logarithmically spaced particle size classes. 

Sinking PSDs were measured from material captured in sediment traps. The standard Hawaii Ocean Time-series (HOT, https://hahana.soest.hawaii.edu/hot/) traps and sampling protocol were used, which includes a 335 µm prefilter to remove zooplankton swimmers. Two sediment trap deployments were sampled: one 81 hr deployment beginning 16-June-2019 and one 73 hr deployment beginning 21-June-2019. For each, trap arrays were deployed at 75, 150, and 300 meter depths. Each array had 12 traps at each depth. On the second deployment one trap per depth was capped and used as a blank so that there were a total of 69 trap measurements (two deployments and three depths, 11 or 12 traps each). After recovery, from each trap a 125 ml split of the trap solution was taken for LISST and IFCB processing. Sinking PSDs were then measured from the LISST in discrete chamber mode. Twenty diffraction measurements were made from each sample before draining each sample back into the 125 ml split bottle; this process was repeated in triplicate, totaling 60 LISST measurements per sediment trap. Trap solution was used as a blank for all LISST measurements.

Addtional details on sampling strategy and procedures can be found in Cael & White (2020).  

Data were analyzed using the standard spherical particle inversion provided by the LISST manufacturer.

Matlab Code used to analyze all LISST data and to reproduce results of Cael and White (2020) are provided.  Detailed information on LISST processing can be found in White et al. (2015). 

Raw data are provided in their original formats (.asc, .log, and .psd). Processed data are provided in Matlab format and are divided into subfolders.

• The ‘LISST’ folder contains all of the LISST data and code used to process data and reproduce the analysis and figures of Cael and White (2020).
• The ‘raw_data’ folder contains all the .asc, .log, and .psd files or .dat files for all of the LISST scans used in the paper (direct outputs of the instrument after samples/scans are run), as well as calibration and ring area files necessary for the LISST inversion, and blank samples collected (applied as in Cael and White, 2020).
• The ‘sed_trap_mat_files’ folder contains processed data used in subsequent analyses and includes the individual suspended samples’ PSDs.
• The ‘code’ folder includes all code used to process the data using Matlab and make key figures in the paper. ‘lisst_process_traps.m’ shows how raw data were converted into PSDs. ‘getscat.m’, ‘invert.p’, and ‘vdcorr.m’ are the LISST manufacturer proprietary code used to invert data and calculate the PSDs using Matlab.

NSF Award Abstract:

Intellectual Merit
The PIs request funds to provide training in leading and organizing research cruises to early career researchers in the areas of Biological and Chemical Oceanography. Participants in this training program would be introduced to pre-cruise planning and logistics, receive training in commonly used oceanographic sampling equipment, and conduct shipboard measurements during a 10-day oceanographic cruise to the North Pacific Subtropical Gyre (NPSG). The goal of this training program is to prepare early career scientists for leading and participating in interdisciplinary oceanographic research at sea.

Broader Impacts
The proposed program addresses the broader impacts criteria successfully. The research cruise and follow-up reports and publications focus on interdisciplinary questions important for advancing the field. Given the rapid changes that oceanic systems are undergoing, it is important to have a cadre of junior scientists who are adept at managing interdisciplinary collaborations and conducting research at sea. The PIs are considering ways to connect with diverse audiences in recruiting participants. The impact on early career oceanographers will be very strong. This will create an experience that will be a major impact on the careers of the trainees, especially if they stay in the oceanography field.