Brief description
The aim of the project was to determine the particulate organic carbon concentration in coastal polynyas and off-shelf sites south of the Polar Front. Data is collected from the CTD deployed at various stations. This record descripbes three datafiles.(1) POC_data: station, pressure, temperature, conductivity, salinity, PAR, total beam attenuation coefficients (c), attenuation by particles (cp), site, particulate organic carbon concentration (from optical measurements), rho, longitude and latitude.
(2) Ammonium: station, pressure, site, ammonium, latitude, longitude
(3) POC_PON_ratio: site, depth, particulate organic carbon concentration (measured) particulate organic nitrogen concentration (measured), C:N ratio.
Lineage
Maintenance and Update Frequency: notPlannedc = -(1 / r) * ln (Tr / 100)
where c = beam attenuation coefficient (m-1), r = beam path length (m), and Tr = beam transmission (%) (Gardner 1995). The beam attenuation coefficient (c) represents the sum of attenuation due to particles (cp), water (csw) and colored dissolved organic matter (CDOM). Scattering and absorption by CDOM is considered negligible in most open ocean waters, so attenuation by particles (cp) equals the total attenuation measured (c) minus the attenuation by water (csw):
cp = c - csw
where csw was derived from measurements of c at 2000 m depth at the off shelf sites, where particle concentrations can be assumed to be negligible.
The POC:cp relationship was assessed based on sites where POC and cp were simultaneously collected. Particulate attenuation, cp, of the profiling transmissometer were linearly correlated with discrete POC concentration (the coefficient of determination, R2 = 0.83). There was no evidence that the intercept of the relationship between the in situ POC concentration and particle attenuation varied by site (p = 0.1), which allowed for the POC concentrations to be pooled across all CTDs for each polynya, and the off-shelf stations. cp was transformed to POC concentration (mg m-3) via a single linear equation:
POC = 26.8 + 370.6cp
Data file contents are as follows:
(1) POC_data (from optical sensor on Seabird CTD): station, pressure, temperature, conductivity, salinity, PAR, total beam attenuation coefficients (c), attenuation by particles (cp), site, particulate organic carbon concentration (from optical measurements), rho, longitude and latitude.
(2) Ammonium (collected from individual CTD Niskin bottles): station, pressure, site, ammonium, latitude, longitude
(3) POC_PON_ratio (collected from individual CTD Niskin bottles): site, depth, particulate organic carbon concentration (measured) particulate organic nitrogen concentration (measured), C:N ratio.
Notes
CreditAntarctic Climate and Ecosystems CRC
Australian Antarctic Division research projects AAS 4131 and 4291
Institute for Marine and Antarctic Studies, University of Tasmania
L. Ratnarajah also received support from BYONIC (ERC award number 724289 awarded to Alessandro Tagliabue)
S. Moreau and C. Genovese were supported by the Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001)
V. Puigcorbé was supported by Edith Cowan University through an Early Career Researcher Grant (G1003456) and an ECU-Collaboration Enhancement Scheme grant
Data time period: 2016-12-08 to 2017-01-21
text: westlimit=119; southlimit=-68.00; eastlimit=148; northlimit=-61.00
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(DATA ACCESS - POC data (optical sensor), and PON/POC data from CTD bottles [file browse])
uri :
https://data.imas.utas.edu.au/attachments/02364e10-ebc0-463a-b690-2c4ed643733c
- DOI : 10.25959/5F360A58B21A7
- global : 02364e10-ebc0-463a-b690-2c4ed643733c