Energy Audits in Fisheries

For each monitored vessel trip of this study, raw-data were stored at a rate of 1 s on hard disks and downloaded at the end of each audit or vessel monitoring for data elaboration. First, a data cleansing process was performed interactively with data wrangling tools, or as batch processing through scripting in order to detect and correct corrupt or inaccurate records. The inconsistencies detected may have been originally caused by corruption in transmission or measurement instruments. Inaccuracy of a single measurement may have been considered acceptable, and related to the inherent technical error of the measurement instrument. Hence, data cleansing focused only on those errors that are beyond small technical variations and that constitute a major shift within or beyond the population distribution. After cleansing, raw-data have been time-averaged at 10 s interval to hold them in a Microsoft Access database. Routines have been finally written specifically to export the time-averaged data into an elaborated ASCII file and made available through this unrestricted repository at <i>Figshare</i> as a Comma-Separated Values (CSV) file. The elaborated dataset comprises 15 fields, which collectively describe the sailing or finding fish, and towing activities associated with the energy consumption and fuel-related GHG emission. All field codes and definitions are described in Table 3 (also available here), so that to facilitate data re-use and re-processing. All raw-data are hosted at CNR servers and they are freely available upon request.

本研究中每一次受监测的船舶航次，原始数据均以每秒1次的采样频率存储于硬盘，并在每次审核或船舶监测作业结束后下载以进行数据加工处理。首先，研究人员借助数据规整工具（data wrangling）开展交互式数据清洗流程，或通过脚本执行批处理操作，以检测并修复损坏或不准确的记录。本次检测到的数据不一致性，最初可能由传输过程中的数据损坏或测量仪器故障引发。单次测量的微小误差通常可被接受，且与测量仪器固有的技术误差相关，因此本次数据清洗仅针对超出微小技术波动范围、且在总体分布内部或外部造成显著偏移的错误。清洗完成后，原始数据以10秒为间隔进行时间平均处理，并存储于Microsoft Access数据库中。随后，研究人员专门编写了定制化脚本，将时间平均后的数据导出为加工后的ASCII文件，并以逗号分隔值（Comma-Separated Values，CSV）格式上传至本无限制公开的Figshare存储库。本加工后的数据集共包含15个字段，可全面描述船舶航行、探鱼及拖网作业活动，并关联能耗与燃料相关的温室气体（Greenhouse Gas, GHG）排放情况。所有字段编码及定义详见表3（本文同步提供），以方便数据的复用与再处理。所有原始数据均存储于CNR服务器，可通过申请免费获取。