Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

CTD sensor and nutrient measurements. Measurements were made at the San Pedro Ocean Time-series (SPOT) station (33 33'N, 118 24'W). Data are also published in Table C1 in the following publication:
Haskell, W. Z., et al. 2016. An organic carbon budget for coastal Southern California determined by estimates of vertical nutrient flux, net community production and export. Deep-Sea Research I, 116, 49-76. doi:10.1016/j.dsr.2016.07.003

See complete methodology in Haskell et al. (2016). In summary: 
This study is part of an effort aimed at characterizing the biological response to upwelling at SPOT on 21 cruises between January 2013 and June 2014; the Upwelling Regime In-Situ Ecosystem Efficiency (Up.R.I.S.E.E.) study.

Nutrients: Samples for dissolved nutrient and pH analysis were collected via Niskin at 12 depths from the surface to 400 m and filtered through 0.8/0.2 um Acrodisc syringe filters. One Nalgene bottle was filled completely leaving no headspace and kept at ambient temperature for 6–8 h until return to the lab where pH was measured using a combination electrode calibrated with buffers of pH 4 and 7, referenced to NBS standards. About 20 of these samples were analyzed for alkalinity and total dissolved inorganic carbon (DIC). To make the measured pH internally consistent with the DIC and alkalinity, all pH values were increased by 0.02, the estimated uncertainty in electrode calibration. After the pH aliquot was taken, samples were refrigerated until silicic acid and phosphate analyses were done colorimetrically at USC with a Hitachi UV/vis-spectrophotometer. Nitrate samples were collected in acid-washed 60 ML HDPE Nalgene bottles and frozen at -20 degrees C until analysis. Nitrate concentrations in samples collected from January to June 2013 were determined by converting nitrate to N2O and quantifying the amount of N2O as integrated sample areas on an Isotope Ratio Mass Spectrometer (IRMS) in the D. Sigman lab at Princeton University. Prior to analyses, nitrite was chemically removed from samples. The remainder of the samples (October 2013 to June 2014) were analyzed for nitrate + nitrite and nitrite only by chemiluminescence. The analytical uncertainty for nitrate and silica concentrations is ~0.5 uM. Samples for DIC were collected at each depth by using a syringe to inject 5–7 mL of filtered water into evacuated vials through a needle-pierced septum. Following measurement of the mass of water, measurements of TCO2 and δ13C were made on a Picarro Cavity Ring-Down Spectrometer at USC. Alkalinity was calculated from DIC and pH using Mehrbach constants. On samples titrated for alkalinity, DIC calculated from the adjusted pH was within +/- 10 umol per kg (+/-1 ssd) of the measured values. Measurements were standardized with Dickson standards from SIO, and alkalinity precision was typically +/- 5 ueq per kg. DOC samples were syringe-filtered into acid-washed and combusted 40 ML borosilicate vials with silicone/PTFE septa caps (Thermo Fisher Scientific). After sampling, samples were acidified with distilled HCl to pH ~2 and refrigerated until analysis on a Shimadzu TOC-VCSN analyzer at Scripps Institute of Oceanography (L. Aluwihare lab). The analytical uncertainty on DOC concentrations based on replicates is ~ 5 uM. Each day's run included the analysis of a deep seawater community standard, and if the concentration of this standard was not between 41 and 42 uM C then all samples were re-analyzed.

CTD data was processed through the standard Seabird Seasave V7 data processing algorithm. 

BCO-DMO Processing:
-modified parameter names to conform with BCO-DMO naming conventions;
-created separate column for date and formatted to yyyy-mm-dd;
-replaced "-" and blanks (missing data) with "nd";
-added site name, lat, and lon from information on metadata form.

The marine biological pump is one of the primary pathways via which anthropogenic carbon dioxide may be sequestered from the atmosphere and exported to the deep ocean as organic carbon. While the link between nutrient supply and high primary productivity in upwelling regions is well established, factors controlling the organic carbon export efficiency of upwelling ecosystems are not well known. Scientists from the University of Southern California and Pomona College plan to determine the factors that control the rates and magnitudes of two components of biological production, Net Community Production (NCP) and Gross Primary Production (GPP), as well as particulate organic carbon export efficiency, at the San Pedro Ocean Time Series, a coastal site in the California Borderland during periods of minimal and high upwelling velocity over a 2-year span. At this site, past and ongoing observations of hydrography and carbon rain will provide an historical context for interpreting results and mechanisms at work.

Rates of NCP and GPP will be quantified at different upwelling intensity, using dissolved oxygen to argon (O2/Ar) ratios and the oxygen triple isotope composition of dissolved oxygen (O2). The export of organic carbon will be established using 234Th (thorium) profiles in the water column, coupled with floating sediment trap deployments, and the development of a carbon isotope balance for the water column. Upwelling will be characterized using non-steady state budgets for atmospheric 7Be (beryllium) input and its depth-integrated decay, as well as estimating rates based on remote measurements of wind stress curl and budgets for dissolved inorganic carbon and silicon. Application of the O2/Ar ratio and the oxygen triple isotope approach will require depth-integrated profiles of these tracers to evaluate the impact of upwelling on mixed layer inputs and use of non-steady state models during seasonal transitions in upwelling. The comprehensive data set to be obtained should provide insights into the organic carbon export efficiency under variable upwelling regimes and help to relate the satellite-based measurements of chlorophyll to the organic carbon export of these highly productive ecosystems.

Broader Impacts: One graduate and one undergraduate student from the University of Southern California and two undergraduate students from Pomona College would be supported and trained as part of this project.