Abstract:

The remotely operated undulating towed vehicle known as the Scanfish was equipped with a SEA-BIRD Scientific fastcast CTD (SBE-49) and oxygen sensor (SBE-43), SEA-BIRD Scientific-Satlantic OCR-507 multispectral radiometer, and four SEA-BIRD Scientific-WET Labs optical instruments: Spectral Absorption and Attenuation meter (AC-s), ECO Triplet Fluorimeter (FL3: chlorophyll-a, Color Dissolved Organic Matter (CDOM) and Phycoerythrin), ECO Triplet Backscattering sensor (BB3: 470 nm, 532 nm, 660 nm) and a C-Star Transmissometer. The Scanfish was towed continuously from the R/V Pelican during the Spring CONCORDE Cruise on March 29-April 3, 2016. The dataset include the date, time, location, depth, temperature, conductivity, salinity, chlorophyll-a fluorescence, CDOM fluorescence, phycoerythrin fluorescence, backscattering 3 wavelengths, attenuation (c) and absorption (a) coefficients at 85 wavelengths, transmittance, irradiance at 6 wavelengths and photosynthetically active radiation (PAR).

Suggested Citation:

Inia M. Soto, Alan Weidemann, Mark Hulbert, Jeffrey Book, Sabrina Parra, Wesley Goode. 2018. CTD and optical data from the remotely operated undulating towed vehicle (Scanfish) collected during Spring R/V Pelican Cruise March 29 - April 3, 2016. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N71N7ZK4

Purpose:

Characterize the seasonal bio-optical and physical properties of the Mississippi Sound and Bight. Capture the tri-dimensional physical and optical properties of the Mississippi and Mobile River Plumes.

Data Parameters and Units:

Year [YYYY], Month [MM], Day [DD], Hour [HH], Minutes [MM], Seconds [SS], Matlab_time (units: UTC-6), Latitude (units: decimal degrees), Longitude (units: decimal degrees), Pressure (units: dbar), Temperature (units: °C), Conductivity (units: S/m), Salinity (units: PSU), Chlorophyll fluorescence [CHL; units: ug/L], Phycoerythrin [PE; units: ppb], Colored Dissolved Organic Matter fluorescence [CDOM; units: ppb], Total Volume Scattering at 470 nm [Beta(470); units: m-1sr-1], Volume Scattering of Particles at 470 nm [BetaP(470); units: m-1sr-1], Backscattering of particles at 470 nm [bbP(470); units: m-1], Total Backscattering at 470 nm [bb(470); units: m-1], Total Volume Scattering at 532 nm [Beta(532); units: m-1sr-1], Volume Scattering of Particles at 532 nm [BetaP(532); units: m-1sr-1], Backscattering of particles at 532 nm [bbP(532); units: m-1], Total Backscattering at 532 nm [bb(532); units: m-1], Total Volume Scattering at 660 nm [Beta(660); units: m-1sr-1], Volume Scattering of Particles at 660 nm [BetaP(660); units: m-1sr-1], Backscattering of particles at 660 nm [bbP(660); units: m-1], Total Backscattering at 660 nm [bb(660); units: m-1], Attenuation coefficient [c; units: m-1; wavelengths: 399.6, 404.3, 408.5, 412.8, 417.1, 422.6, 427.6, 431.8, 436.4, 440.9, 445.6, 450.9, 455.5, 459.7, 464.1, 469.0, 474.0, 479.0, 483.8, 488.3, 492.8, 497.0, 501.7, 506.4, 511.4, 516.5, 521.5, 525.8, 530.3, 534.8, 539.6, 543.9, 548.8, 553.4, 557.5, 561.6, 565.9, 570.5, 574.7, 578.8, 583.2, 587.8, 592.5, 596.9, 602.1, 606.6, 611.3, 616.0, 620.7, 625.5, 629.9, 634.4, 638.7, 643.1, 647.8, 652.7, 657.2, 661.9, 666.4, 670.9, 675.2, 679.6, 683.8, 688.2, 692.3, 696.3, 700.4, 704.1, 707.8, 711.3, 715.0, 718.8, 722.0, 725.1, 728.8, 731.9, 734.8, 737.8, 741.0, 743.7, 746.2, 748.7, 751.1], Absorption coefficient [a; units: m-1; wavelengths: 401.0, 405.7,410.3, 414.4, 418.9, 424.0, 429.0, 433.2, 438.0, 442.5, 447.4, 452.5, 456.9, 461.5, 466.1, 470.6, 475.9, 480.6, 485.5, 489.7, 494.6, 498.8, 503.5, 508.0, 513.0, 518.0, 523.0, 527.5, 532.0, 536.5, 541.3, 545.7, 550.2, 555.1, 558.2, 562.7, 566.8, 571.3, 575.4, 579.5, 583.9, 588.5, 592.7, 597.4, 602.1, 606.8, 611.7, 616.4, 621.2, 625.5, 630.0, 634.5, 639.0, 643.5, 648.1, 652.5, 657.3, 661.9, 666.2, 670.9, 675.4, 679.6, 683.8, 688.1, 692.1, 696.2, 699.9, 703.7, 707.5, 710.8, 714.5, 718.0, 721.6, 724.8, 728.4, 731.5, 734.5, 737.0, 740.5, 743.0, 745.3, 748.3, 750.8], Transmittance [CSTAR; units: Volts], Downwelling Irradiance [ED; units: µW cm-2 nm-1; wavelengths: 411.4, 443.3, 490.6, 532.7, 555.4, 669.5], Photosynthetically Available radiation [PAR; units: µMol m-2 sec-1], Ancillary measurements for the OCR instrument [VS; units: Volts and VA; units: Volts]

Methods:

The remotely operated undulating towed vehicle known as the Scanfish was towed continuously from the R/V Pelican during the Spring CONCORDE Cruise on March 29-April 3, 2016. It was equipped with a SEA-BIRD Scientific fastcast CTD (SBE-49) and oxygen sensor (SBE-43), SEA-BIRD Scientific-Satlantic OCR-507 multispectral radiometer, and four SEA-BIRD Scientific-WET Labs optical instruments: Spectral Absorption and Attenuation meter (AC-s), ECO Triplet Fluorimeter (FL3: chlorophyll-a, Color Dissolved Organic Matter (CDOM) and Phycoerythrin), ECO Triplet Backscattering sensor (BB3: 470 nm, 532 nm, 660 nm) and a C-Star Transmissometer. All the instruments were interfaced with a WET Labs DH4 data logger. The AC-s instrument was calibrated prior to and post cruise. Calibration of the ac-s included running Nanopure water through the systems using a gravity feed as the instruments were allowed to stabilize for some time interval (≈5 min to ≈10 min). The calibration procedure included obtaining the clear water calibration before and after cleaning the absorption and scattering tubes. An update to instrument device files was applied in real-time if it was deemed that new corrections were necessary to assure good quality measurements. Post processing of the ac-s data will follow the WET Labs protocols. First, the ac-s data was merged and binned with the other instruments in the Scanfish using the WetLabs Archive Processing Software (WAP). The software can be found here: http://wetlabs.com/software/wet-labs-archive-processing-wap. Due to the distance between the CTD and the AC-s within the instrument, the AC-s data was corrected for a 13 second lag-time before the temperature and salinity corrections were applied. Water absorption corrections for temperature and salinity were applied using the CTD (SBE-49) data following [Pegau et al., 1997; DOI: 10.1364/ao.36.006035]. The final correction was the scattering correction. For this, we used the method outline in Rottgers et al., 2013 (DOI: 10.1016/j.mio.2013.11.001). The OCR-507 data was processed in WAP and binned to the other data similarly. The WAP software applies the instrument calibration and converts the raw data into downwelling irradiance (ED) and PAR. However, no further corrections were applied to this dataset. The ECO BB3 and FL3 were process using WAP and instrument calibration and equations were directly applied by the WAP software as default and using the instrument calibration files from Wet-LABS. The transmissometer data is raw data. The calibration file did not provided the conversion units therefore it is in Volts.

Provenance and Historical References:

W. Scott Pegau, Deric Gray, and J. Ronald V. Zaneveld. 1997. Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity. Applied Optics 36(24), 6035-6046. https://doi.org/10.1364/AO.36.006035 R. Röttgers, D. McKee, and S.B. Woźniak. 2013. Evaluation of scatter corrections for ac-9 absorption measurements in coastal waters. Methods in Oceanography 7, 21-39. https://doi.org/10.1016/j.mio.2013.11.001

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