Data to support Two scales of distribution and biomass of Antarctic krill (Euphausia superba) in the eastern sector of the CCAMLR Division 58.4.2 (55°E to 80°E)

This data may be used to reproduce the analyses (including figures and tables), of 'Two scales of distribution and biomass of Antarctic krill (Euphausia superba) in the eastern sector of the CCAMLR Division 58.4.2 (55°E to 80°E)'.The data describe krill biomass density distribution and krill net samples (krill total length and krill wetmass) collected during the 2021 TEMPO voyage on R/V Investigator.During the TEMPO voyage krill biomass was estimated using observations from two sampling instruments: a calibrated EK80 scientific echosounder operating at 120 kHz and an rectangular midwater trawl (RMT 1+8). The supporting data sets, all in CSV format, are split by instrument type. The EK80 has two datafiles:1. krill_density.csv – krill areal density from the TEMPO transects, and2. krill_swarms.csv -krill swarms detected during the TEMPO transects.The RMT1+8 has four datafiles1. net_locations.csv2. krill_lengths.csv3. krill_wet_mass_to_length.csv4. krill_wet_mass_to_length_model_predictions.csvThe fields (columns) in each data file are:krill_density.csv"lat_M" – centre latitude of an echo integration interval [degrees] (dd.ddddd) WGS84 spheroid (GPS latitude)"lon_M" - centre longitude of an echo integration interval [degrees] (dd.ddddd) WGS84 spheroid (GPS longitude),"areal_biomass_density_g_per_m2" – Echo integration interval krill areal biomass density [g wet-mass / m^2]"daynight" – flag for when the sampling took place [day/night]"survey" – Either the main survey for the TEMPO biomass survey or the smaller-scale ‘Mawson box’ surveykrill_swarms.csv"transect" – transect number"lat" – latitude [degrees] (dd.ddddd) WGS84 spheroid (GPS latitude) "swarm_depth_m" – mean depth of a krill swarm [m]"daynight" – flag for when the sampling took place [day/night]”volumetric_density_g_per_m3" – krill swarm internal volumetric biomass density [g wet-mass / m^3]net_locations.csv"station" – Station name for net trawl R for routine haul, T for target trawl"lat" – mean latitude of a net trawl [degrees] (dd.ddddd) WGS84 spheroid (GPS latitude)"lon" – mean longitude of a net trawl [degrees] (dd.ddddd) WGS84 spheroid (GPS longitude)"daynight" – flag for when the sampling took place [day/night]krill_lengths.csv"station" – Station name for net trawl R for routine haul, T for target trawl"total_length_mm” – total length of an individual krill [mm]krill_wet_mass_to_length.csv"total_length_mm" – total length of an individual krill [mm]"wet_mass_g" - wet-mass an individual krill [g]krill_wet_mass_to_length_model_predictions.csv"total_length_mm" - total length of an individual krill [mm]"predicted_wet_mass_g" – predicted mean wet-mass an individual krill of length ("total_length_mm" ) [g]"LB_wet_mass_g" – Lower bound (lower 95% confidence interval) for the predicted_wet_mass_g [g]"UB_wet_mass_g"– Upper bound (upper 95% confidence interval) for the predicted_wet_mass_g [g]

本数据集可用于复现《南极磷虾（Euphausia superba）在南极海洋生物资源养护委员会（Commission for the Conservation of Antarctic Marine Living Resources，CCAMLR）58.4.2分区东部海域（55°E至80°E）的两种分布与生物量尺度》一文的分析结果（含图表与表格）。
本数据集涵盖2021年TEMPO航次采集的南极磷虾生物量密度分布数据，以及该航次获取的磷虾网采样品数据（包括磷虾总长度与湿重），该航次由调查船R/V Investigator执行。
在TEMPO航次中，研究人员采用两台采样仪器估算磷虾生物量：一台经过校准的120 kHz科学回声测深仪EK80，以及矩形中层拖网（RMT 1+8）。所有配套数据集均采用CSV格式，按仪器类型拆分。
EK80对应2个数据文件：
1. krill_density.csv：存储TEMPO航次断面的磷虾面积密度数据；
2. krill_swarms.csv：存储TEMPO航次断面探测到的磷虾群数据。
RMT 1+8对应4个数据文件：
1. net_locations.csv
2. krill_lengths.csv
3. krill_wet_mass_to_length.csv
4. krill_wet_mass_to_length_model_predictions.csv

以下为各数据文件的字段（列）说明：
krill_density.csv
- "lat_M"：回声积分区间的中心纬度（单位：度，格式为dd.ddddd），采用WGS84椭球体基准（GPS纬度）
- "lon_M"：回声积分区间的中心经度（单位：度，格式为dd.ddddd），采用WGS84椭球体基准（GPS经度）
- "areal_biomass_density_g_per_m2"：回声积分区间内的单位面积磷虾生物量密度（单位：克湿重/平方米）
- "daynight"：采样时段标识（昼/夜）
- "survey"：调查类型，分为TEMPO生物量主调查与小型“莫森区块”（Mawson box）调查

krill_swarms.csv
- "transect"：断面编号
- "lat"：纬度（单位：度，格式为dd.ddddd），采用WGS84椭球体基准（GPS纬度）
- "swarm_depth_m"：磷虾群平均深度（单位：米）
- "daynight"：采样时段标识（昼/夜）
- "volumetric_density_g_per_m3"：磷虾群内部单位体积生物量密度（单位：克湿重/立方米）

net_locations.csv
- "station"：拖网站位名称，R代表常规拖网，T代表目标拖网
- "lat"：拖网的平均纬度（单位：度，格式为dd.ddddd），采用WGS84椭球体基准（GPS纬度）
- "lon"：拖网的平均经度（单位：度，格式为dd.ddddd），采用WGS84椭球体基准（GPS经度）
- "daynight"：采样时段标识（昼/夜）

krill_lengths.csv
- "station"：拖网站位名称，R代表常规拖网，T代表目标拖网
- "total_length_mm"：单只磷虾的总长度（单位：毫米）

krill_wet_mass_to_length.csv
- "total_length_mm"：单只磷虾的总长度（单位：毫米）
- "wet_mass_g"：单只磷虾的湿重（单位：克）

krill_wet_mass_to_length_model_predictions.csv
- "total_length_mm"：单只磷虾的总长度（单位：毫米）
- "predicted_wet_mass_g"：对应长度（total_length_mm）的单只磷虾预测平均湿重（单位：克）
- "LB_wet_mass_g"：预测湿重的95%置信区间下限（单位：克）
- "UB_wet_mass_g"：预测湿重的95%置信区间上限（单位：克）