Process_Description:
Beginning on March 25, 2018, instruments to measure time-series data of water quality, water level, flow velocity, and mixing between water masses within flooded coastal cave passages were deployed at four locations in the Ox Bel Ha Cave System, accessed through the sinkhole Cenote Bang approximately 6.3 km inland, just south of Tulum (Quintana Roo, Mexico). The instruments were deployed in the cave environment by SCUBA divers who followed protocols established by the USGS, American Academy of Underwater Sciences, and the National Speleological Society Cave Diving Section. A dissolved oxygen sensor was deployed in the entrance sinkhole pool. A fiberglass platform containing an acoustic doppler current profiler (Nortek Aquadopp) and buoys to achieve positive buoyancy was installed on the cave ceiling at approximately 3.5 m water depth in freshwater approximately 20 m horizontal distance from the entrance sinkhole pool. Next to the fiberglass platform, at the same depth, a HOBO dissolved oxygen sensor was co-deployed with an OsmoSampler and packed in a plastic box (42 cm wide, 42 cm long, and 33 cm high) to allow the diver to safely deploy the full set of devices. In the same location, but below a halocline at 7.5 m water depth in the brackish water, another set of equipment (including loggers measuring dissolved oxygen, conductivity, and water level) was co-deployed with an OsmoSampler in another plastic box. Approximately 100 m upstream and westward in the main passage from these instruments, the following set of instruments were co-deployed after a northern curvature in the passage at 21 m water depth in completely saline water; EA400 acoustic profiler, a water level logger, and a dissolved oxygen logger. In the vicinity of this bundle, tilt-current meters (TCMs) were deployed at 17 m and 22 m water depth using lead dive weights to anchor them on the rocky bottom. In addition, a barometric pressure gauge was deployed on the surface on a roof of a house approximately 15 m above the ground. All deployed sensors were recovered on August 1, 2018, using divers for all submerged sensors. Upon recovery, the data were retrieved from the instruments, archived for safe keeping, and made available for processing. The OsmoSampler time-series is not part of this release.
Process_Date: 20180801
Process_Description:
Data from the HOBO and TCM loggers were downloaded in csv format using dedicated software provided by the two companies. Where it was needed, barometric data that was obtained from the pressure logger deployed on the surface was used to correct the time-series data downloaded from the HOBO loggers using the HOBO software. The raw or vendor post-processed data files from each sensor were processed and converted to netCDF using stglib python libraries, a package of code to process data consistent with procedures of the USGS Coastal and Marine Hazards and Resources Program. In stglib, attributes conforming to Climate and Forecast (CF) Conventions version 1.8 were added. All times are in Coordinated Universal Time (UTC). Data quality assurance and quality control (QAQC) was performed by inspecting all variables and replacing spurious values with the fill value. Details of which portions of data were flagged and replaced are available in the metadata in each netCDF file and information about the individual QAQC trimming functions are available in the stglib documentation (
https://stglib.readthedocs.io/en/latest/) in the "Instrument configuration file" section. The netCDF files are named using the convention ####XZZZ-a.nc where '####' is the mooring number, 'X' is the position on the mooring of the sensor with 1 being closest to the surface, and 'ZZZ' is a 2 or 3 character abbreviation for the instrument that was deployed. For example, in the file 11141ea-a.nc, '1114' is the mooring number, '1' is the position of the sensor on the mooring, and 'ea' refers to the Echologger EA400 sensor. The '-a' refers to Best Basic Version (BBV) of the processed data.
