Enrichment of trajectories with environmental data, and standardisation of tagging data using NetCDF

Geolocalisation and trajectory analysis can aid in understanding the ecological processes driving an
organism. By associating satellite-derived environmental data with individual trajectories of
electronically-tagged organisms, it could be possible to define environmental characteristics of the tagged
species’ functional habitats (i.e., reproduction, nutrition). These data can also help identify biotic envelopes
or predict the effects of climate change on marine species distributions. The objective of the present work,
undertaken as a collaboration between IFREMER and IRD, is to standardize electronic tag data files into
network common data format (NetCDF) format, following the standards defined within the POPSTAR
project for tag data (doi http://dx.doi.org/10.13155/34980 ), and enrich the positional data with
satellite-derived surface environment data (e.g., sea surface temperature, salinity, sea level) and
model-derived environment data at observed depths (e.g., temperature, salinity, currents). We accounted for
positional uncertainty using 95%, 75%, and 50% uncertainty polygons around the estimated positions of
individuals. We summarised environmental conditions within these uncertainty polygons using the mean,
minimum, maximum, quantiles, and standard deviation of the selected enrichment parameter. We generated
generic codes to enable the automatic enrichment of position data from points and polygons. Furthermore,
we developed algorithms to convert the enriched data into NetCDF format for subsequent visualisation and
analysis.