Float profile data collected during surface ascents in the Sargasso Sea from 2013-2014 (NCEI Accession 0278798)

Acquisition Description:
Multiple deployments of two Sea-Bird Scientific Navis BGCi floats (numbers F033 and F034) equipped with CTDs, transmissometers, O 2 optodes, backscattering (700 nm), fluorescence (chlorophyll, colored dissolved organic matter), and tilt sensors were conducted between July 2013 and November 2014 in conjunction with Bermuda Atlantic Time-series Study cruises. Short-term deployments (1.5 – 3 days) followed by recovery of the floats were conducted during four monthly BATS cruises in July – October 2013 and one cruise in March 2014. Both floats were deployed during the July and August 2013 cruises and float F034 was deployed for the remaining cruises. Each float collected one profile per cruise with the exception of the August 2013 cruise, during which the two floats together collected 13 profiles. During short-term deployments, floats first completed an initial descent and ascent without parking, then completed 1 or 2 more profile cycles with different, consecutive target depths. Following the initial descent/ascent described above, the short-term profile cycles were structured as described below for long-term deployments. In addition to the short-term cruise deployments, F033 profiled continuously from October 2013 until early April 2014, yielding 77 profiles, and F034 profiled continuously from March 2014 until late November 2014, yielding 139 profiles. During these long-term deployments, a typical cycle consisted of 1) the descent to the target park depth, 2) a park phase at the target depth lasting 1.5 – 2.5 days during which measurements are made every 15 minutes, 3) a descent to 1000 dbar, 4) an ascent to the surface during which measurements are made, and 5) a surface telemetry phase, during which a GPS fix is obtained, data are uploaded via Iridium, and instructions for the next cycle are downloaded. During long-term deployments, floats cycled through park phases at 150/200, 300, 500, and 1000 dbar every 7 days, spending 2.5 days at 1000 dbar and 1.5 days at the shallower depths. The sequence of park phase depth at the three shallowest depths was varied between each 7-day cycle over a 21-day period to avoid aliasing in particle flux profiles.

A float firmware error early in the project prevented collection of upper water column data in some of the short-term deployments. This was remedied before long-term deployment of the floats commenced. The floats occasionally performed a reboot during ascent profiles. The affected profiles are missing data for some pressure bins. Colored dissolved organic matter data are not available for float F034 profiles from cruises B295 and B296 due to sensor malfunction.

Profile data were acquired during the ascent to the surface following each park phase acquisition at a sampling rate of 4 dbar below 500 dbar and 2 dbar above 500 dbar.

Related References:

References

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