Submesoscale NCP and GPP rates from Underway O 2 /Ar and Triple Oxygen Isotope Measurements Rachel H. R. Stanley Woods Hole Oceanographic Institution

NCP = Net Community Production = Net amount of C taken up by ecosystem, should equal export production NPP = Net Primary Production = autotrophic component of NCP only GPP = Gross Primary Production = total photosynthesis Primer on Biological Production

ADVANTAGES – In situ techniques – Integrate over one to two weeks – “Easy” to make measurements so high resolution possible – Includes contribution from DOC – Can be done in underway mode but need some depth info PROBLEMS – Rely on gas exchange estimate – What exact time/spatial scale are you measuring? – Have to account for mixing, entrainment, etc. – Doesn’t work well in upwelling regions Gas Tracers for Measuring PP

Method: NCP from O 2 and Ar Oxygen produced by photosynthesis, consumed by respiration, but also affected by physics Ar is abiotic analogue for O 2 because similar physiochemical properties

EIMS for Continuous Measurements Recent advance: continuous at-sea measurements of O 2 and Ar using an Equilibrator Inlet Mass Spectrometer (EIMS) yield thousands of data points of NCP

EIMS for Continuous Measurements Recent advance: continuous at-sea measurements of O 2 and Ar using an Equilibrator Inlet Mass Spectrometer (EIMS) yield thousands of data points of NCP Ocean Mixed Layer Wet Lab (at-sea) Equilibrator Cartridge Quadrupole Mass Spectrometer (QMS) Measure O 2 and Ar gas from headspace Underway Water

EIMS for Continuous Measurements Recent advance: continuous at-sea measurements of O 2 and Ar using an Equilibrator Inlet Mass Spectrometer (EIMS) yield thousands of data points of NCP

Two Datasets from the Pacific From Stanley et al, GBC, 2010 WEP STP

Not many variables measured at high enough resolution for comparison with NCP Temperature is a measure of physical variability and frontal instabilities Correlation analysis is not enough – sections with positive and negative correlation, lags, etc. NCP and Temperature From Stanley et al, GBC, 2010 WEP

Power spectra for temperature and O 2 /Ar similar at low frequency, but differ at high frequency Power Spectra

PDF=power density function Temperature and O 2 /Ar differ at scales close to 4 km, similar at scales >10 km Scales of Variability

PDF=power density function Temperature and O 2 /Ar differ at scales close to 4 km, similar at scales >10 km Scales of Variability

Similar variability between NCP and physics Kurtosis -- at scales ranging from 8 to 50 km -- shows similar variability of temperature and O 2 /Ar (and thus NCP) Suggests that processes are related  physics is “priming the pump” for biology But to examine link, really need Process Studies!

GPP = Gross Primary Production = total photosynthetic flux Mass independent fractionation results in atmospheric 17  different than photosynthetic 17 . Sampled discretely while underway or from niskins GPP from Triple Oyxgen Isotopes

GPP and NPP “STP” cruise GPP and NPP similar pattern GPP/NPP ratio equals 3 to 5 BUT there are differences  autotrophic respiration (R A ), Mehler reaction, or photo- respiration NPP=GPP-R A

GPP, NPP and NCP Do I want any text? NCP=GPP-R A -R H

Energy Flow Diagrams Diagrams drawn to scale Differences in regions: total amount of energy & its distribution between boxes Caveats: measurement uncertainty, VGPM  NPP

NCP can be measured continuously from underway system from O 2 /Ar ratios Submesoscale variability in NCP similar to that in physics GPP can be measured discretely from underway water or Niskins Combination of GPP, NCP and NPP describe energy flow  variations in autotrophic respiration may be important NEED some CTD cast samples to correct for entrainment (Nicholson et al, submitted) Conclusions

Collaborators: – Raf Ferrari (MIT), Michael Bender (Princeton), John Kirkpatrick (UW) – Captain and crew of R/V Kilo Moana and NOAA ship Kai’imomoana Funding Sources: – NSF Chemical Oceanography – WHOI Penzance Fund for Assistant Scientists Acknowledgements