Hydrodynamic and hydrological processes within a variety of coral reef lagoons: field observations during six cyclonic seasons in New Caledonia

Abstract. From 2014 to 2021 during the cyclone seasons, extensive monitoring of the
hydrodynamics within a variety of lagoons of New Caledonia was conducted as
a part of the PRESENCE project (PRESsures on coral Ecosystems of New
CalEdonia). The PRESENCE project is aimed at building an efficient
representation of the land–lagoon–ocean continuum at Grande Terre, New
Caledonia's main island. Overall, coastal physical observations encompassed
five different lagoons (four of which were never before monitored) and at
least eight major atmospheric events ranging from tropical depressions to
category 4 cyclones. The main objectives of this study were to characterize
the processes controlling the hydrodynamics and hydrology of these lagoons
(e.g., ocean–lagoon exchanges, circulation, level dynamics, temperature, and
salinity variability), and to capture the magnitude of change during extreme
events. An additional objective was to compile an adequate data set for
future use in high-resolution hydrodynamic models. Autonomous oceanographic
instruments were moored at strategic locations to collect time series of
temperature, salinity, pressure, and Eulerian currents. Additionally,
Lagrangian surface currents were observed through deploying drifter buoys,
and cross-shore hydrological profile radials were carried out using CTDs (conductivity, temperature, depth). In
total, five survey campaigns were conducted, beginning with the SPHYNX
campaign which lasted 15 months (December 2014 to February 2016) in the
Hienghène–Touho lagoon and ended with the 9 months NEMO campaign
(September 2020 to April 2021) in Moindou lagoon. Between these were the 5 months NOUMEA campaign (December 2016 to April 2017) in Noumea lagoon, the 6
months ELADE campaign (February to August 2018) in the Poe lagoon, and the 5 months CADHYAK campaign (December 2019 to May 2020) in Koumac lagoon. In
addition to characterizing these lagoons, the data set identifies important
features and processes, such as the presence of internal waves on forereefs,
wave-driven fluxes over reef barriers, and exchanges through passes.
Signatures from strong events were also identified, including surges,
thermal drops inside lagoons, and massive flash flood plume dispersion. Raw
data sets were processed, controlled for quality, validated, and analyzed.
Processed files are made publicly available in dedicated repositories on the
SEANOE marine data platform in NetCDF format. Links (DOI) of
individual data sets are provided herein.
