Palevsky Hilary I.

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Palevsky

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Hilary I.

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Discrepant estimates of primary and export production from satellite algorithms, a biogeochemical model, and geochemical tracer measurements in the North Pacific Ocean

(John Wiley & Sons, 2016-08-30) Palevsky, Hilary I. ; Quay, Paul D. ; Nicholson, David P.

Estimates of primary and export production (PP and EP) based on satellite remote sensing algorithms and global biogeochemical models are widely used to provide year-round global coverage not available from direct observations. However, observational data to validate these approaches are limited. We find that no single satellite algorithm or model can reproduce seasonal and annual geochemically determined PP, export efficiency (EP/PP), and EP rates throughout the North Pacific basin, based on comparisons throughout the full annual cycle at time series stations in the subarctic and subtropical gyres and basin-wide regions sampled by container ship transects. The high-latitude regions show large PP discrepancies in winter and spring and strong effects of deep winter mixed layers on annual EP that cannot be accounted for in current satellite-based approaches. These results underscore the need to evaluate satellite- and model-based estimates using multiple productivity parameters measured over broad ocean regions throughout the annual cycle.
Linking oxygen and carbon uptake with the Meridional Overturning Circulation using a transport mooring array

(Oceanography Society, 2022-01-07) Atamanchuk, Dariia ; Palter, Jaime B. ; Palevsky, Hilary I. ; Le Bras, Isabela A. ; Koelling, Jannes ; Nicholson, David P.

The Atlantic Meridional Overturning Circulation (AMOC) is a system of ocean currents that transports warm, salty water poleward from the tropics to the North Atlantic. Its structure and strength are monitored at several latitudes by mooring arrays installed by the international ocean sciences community. While the main motivation for deploying these mooring arrays is to understand the AMOC’s influence on Northern Hemisphere climate, the circulation system also plays a crucial role in distributing oxygen (O2) and carbon dioxide (CO2) throughout the global ocean. By adding O2 sensors to several of the moorings at 53°N–60°N (Figure 1) in the western Labrador Sea, Koelling et al. (2021) demonstrated that the formation of deep water, in which the AMOC brings surface water to the deep ocean, is important for supplying the oxygen consumed by deep-ocean ecosystems throughout the North Atlantic. Additionally, variability in the deep-water formation has been linked to changes in the amount of anthropogenic CO2 stored in the subpolar ocean (Raimondi et al., 2021). These studies, using data collected during research cruises and a small number of moored sensors, showed that deep-water formation and the AMOC are key to oxygen and carbon cycles in the North Atlantic. However, the common assumption that the magnitude and variability of O2 and CO2 uptake by the ocean are tied to the dynamics of the AMOC has never been evaluated on the basis of direct observations.
Temperature, salinity, fluorescence, and dissolved O2/Ar ratios measured continuously underway onboard basin-wide transects of the North Pacific from Hong Kong to Long Beach, CA

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-07-14) Palevsky, Hilary I. ; Quay, Paul

Temperature, salinity, fluorescence, and dissolved O2/Ar ratios were measured continuously from an underway seawater system on board commercial container ships OOCL Tianjin and OOCL Tokyo. Measurements were made from May 2011 to August 2012 during basin-wide transects of the North Pacific Ocean while traversing from Hong Kong to Long Beach, CA For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/831046
The annual cycle of gross primary production, net community production, and export efficiency across the North Pacific Ocean

(John Wiley & Sons, 2016-02-27) Palevsky, Hilary I. ; Quay, Paul D. ; Lockwood, Deirdre E. ; Nicholson, David P.

We measured triple oxygen isotopes and oxygen/argon dissolved gas ratios as nonincubation-based geochemical tracers of gross oxygen production (GOP) and net community production (NCP) on 16 container ship transects across the North Pacific from 2008 to 2012. We estimate rates and efficiency of biological carbon export throughout the full annual cycle across the North Pacific basin (35°N–50°N, 142°E–125°W) by constructing mixed layer budgets that account for physical and biological influences on these tracers. During the productive season from spring to fall, GOP and NCP are highest in the Kuroshio region west of 170°E and decrease eastward across the basin. However, deep winter mixed layers (>200 m) west of 160°W ventilate ~40–90% of this seasonally exported carbon, while only ~10% of seasonally exported carbon east of 160°W is ventilated in winter where mixed layers are <120 m. As a result, despite higher annual GOP in the west than the east, the annual carbon export (sequestration) rate and efficiency decrease westward across the basin from export of 2.3 ± 0.3 mol C m−2 yr−1 east of 160°W to 0.5 ± 0.7 mol C m−2 yr−1 west of 170°E. Existing productivity rate estimates from time series stations are consistent with our regional productivity rate estimates in the eastern but not western North Pacific. These results highlight the need to estimate productivity rates over broad spatial areas and throughout the full annual cycle including during winter ventilation in order to accurately estimate the rate and efficiency of carbon sequestration via the ocean's biological pump.
How choice of depth horizon influences the estimated spatial patterns and global magnitude of ocean carbon export flux

(John Wiley & Sons, 2018-05-05) Palevsky, Hilary I. ; Doney, Scott C.

Estimated rates and efficiency of ocean carbon export flux are sensitive to differences in the depth horizons used to define export, which often vary across methodological approaches. We evaluate sinking particulate organic carbon (POC) flux rates and efficiency (e‐ratios) in a global earth system model, using a range of commonly used depth horizons: the seasonal mixed layer depth, the particle compensation depth, the base of the euphotic zone, a fixed depth horizon of 100 m, and the maximum annual mixed layer depth. Within this single dynamically consistent model framework, global POC flux rates vary by 30% and global e‐ratios by 21% across different depth horizon choices. Zonal variability in POC flux and e‐ratio also depends on the export depth horizon due to pronounced influence of deep winter mixing in subpolar regions. Efforts to reconcile conflicting estimates of export need to account for these systematic discrepancies created by differing depth horizon choices.
Pump it Up workshop report

(Woods Hole Oceanographic Institution, 2017-10-20) Buesseler, Ken O. ; Adams, Allan ; Bellingham, James G. ; Dever, Mathieu ; Edgcomb, Virginia P. ; Estapa, Margaret L. ; Frank, Alex ; Gallager, Scott M. ; Govindarajan, Annette F. ; Horner, Tristan J. ; Hunter, Jon ; Jakuba, Michael V. ; Kapit, Jason ; Katija, Kakani ; Lawson, Gareth L. ; Lu, Yuehan ; Mahadevan, Amala ; Nicholson, David P. ; Omand, Melissa M. ; Palevsky, Hilary I. ; Rauch, Chris ; Sosik, Heidi M. ; Ulmer, Kevin M. ; Wurgaft, Eyal ; Yoerger, Dana R.

A two-day workshop was conducted to trade ideas and brainstorm about how to advance our understanding of the ocean’s biological pump. The goal was to identify the most important scientific issues that are unresolved but might be addressed with new and future technological advances.
Influence of biological carbon export on ocean carbon uptake over the annual cycle across the North Pacific Ocean

(John Wiley & Sons, 2017-01-21) Palevsky, Hilary I. ; Quay, Paul D.

We evaluate the influences of biological carbon export, physical circulation, and temperature-driven solubility changes on air-sea CO2 flux across the North Pacific basin (35°N–50°N, 142°E–125°W) throughout the full annual cycle by constructing mixed layer budgets for dissolved inorganic carbon (DIC) and pCO2, determined on 15 container ship transects between Hong Kong and Long Beach, CA, from 2008 to 2012. Annual air-sea CO2 flux is greatest in the western North Pacific and decreases eastward across the basin (2.7 ± 0.9 mol C m−2 yr−1 west of 170°E, as compared to 2.1 ± 0.3 mol C m−2 yr−1 east of 160°W). East of 160°W, DIC removal by annual net community production (NCP) more than fully offsets the DIC increase due to air-sea CO2 flux. However, in the region west of 170°E influenced by deep winter mixing, annual NCP only offsets ~20% of the DIC increase due to air-sea CO2 flux, requiring significant DIC removal by geostrophic advection. Temperature-driven solubility changes have no net influence on pCO2 and account for <25% of annual CO2 uptake. The seasonal timing of NCP strongly affects its influence on air-sea CO2 flux. Biological carbon export from the mixed layer has a stronger influence on pCO2 in summer when mixed layers are shallow, but changes in pCO2 have a stronger influence on air-sea CO2 flux in winter when high wind speeds drive more vigorous gas exchange. Thus, it is necessary to determine the seasonal timing as well as the annual magnitude of NCP to determine its influence on ocean carbon uptake.
The North Atlantic biological pump : insights from the Ocean Observatories Initiative Irminger Sea Array

(The Oceanography Society, 2018-02-09) Palevsky, Hilary I. ; Nicholson, David P.

The biological pump plays a key role in the global carbon cycle by transporting photosynthetically fixed organic carbon into the deep ocean, where it can be sequestered from the atmosphere over annual or longer time scales if exported below the winter ventilation depth. In the subpolar North Atlantic, carbon sequestration via the biological pump is influenced by two competing forces: a spring diatom bloom that features large, fast-sinking biogenic particles, and deep winter mixing that requires particles to sink much further than in other ocean regions to escape winter ventilation. We synthesize biogeochemical sensor data from the first two years of operations at the Ocean Observatories Initiative Irminger Sea Array of moorings and gliders (September 2014–July 2016), providing the first simultaneous year-round observations of biological carbon cycling processes in both the surface ocean and the seasonal thermocline in this critical but previously undersampled region. These data show significant mixed layer net autotrophy during the spring bloom and significant respiration in the seasonal thermocline during the stratified season (~5.9 mol C m–2 remineralized between 200 m and 1,000 m). This respired carbon is subsequently ventilated during winter convective mixing (>1,000 m), a significant reduction in potential carbon sequestration. This highlights the importance of year-round observations to accurately constrain the biological pump in the subpolar North Atlantic, as well as other high-latitude regions that experience deep winter mixing.
Perspectives on Chemical Oceanography in the 21st century : participants of the COME ABOARD Meeting examine aspects of the field in the context of 40 years of DISCO

(Elsevier, 2017-09-08) Fassbender, Andrea ; Palevsky, Hilary I. ; Martz, Todd R. ; Ingalls, Anitra ; Gledhill, Martha ; Fawcett, Sarah E. ; Brandes, Jay A. ; Aluwihare, Lihini I. ; COME ABOARD ; DISCO XXV

The questions that chemical oceanographers prioritize over the coming decades, and the methods we use to address these questions, will define our field's contribution to 21st century science. In recognition of this, the U.S. National Science Foundation and National Oceanic and Atmospheric Administration galvanized a community effort (the Chemical Oceanography MEeting: A BOttom-up Approach to Research Directions, or COME ABOARD) to synthesize bottom-up perspectives on selected areas of research in Chemical Oceanography. Representing only a small subset of the community, COME ABOARD participants did not attempt to identify targeted research directions for the field. Instead, we focused on how best to foster diverse research in Chemical Oceanography, placing emphasis on the following themes: strengthening our core chemical skillset; expanding our tools through collaboration with chemists, engineers, and computer scientists; considering new roles for large programs; enhancing interface research through interdisciplinary collaboration; and expanding ocean literacy by engaging with the public. For each theme, COME ABOARD participants reflected on the present state of Chemical Oceanography, where the community hopes to go and why, and actionable pathways to get there. A unifying concept among the discussions was that dissimilar funding structures and metrics of success may be required to accommodate the various levels of readiness and stages of knowledge development found throughout our community. In addition to the science, participants of the concurrent Dissertations Symposium in Chemical Oceanography (DISCO) XXV, a meeting of recent and forthcoming Ph.D. graduates in Chemical Oceanography, provided perspectives on how our field could show leadership in addressing long-standing diversity and early-career challenges that are pervasive throughout science. Here we summarize the COME ABOARD Meeting discussions, providing a synthesis of reflections and perspectives on the field.
Nonuniform ocean acidification and attenuation of the ocean carbon sink

(John Wiley & Sons, 2017-08-16) Fassbender, Andrea ; Sabine, Christopher L. ; Palevsky, Hilary I.

Surface ocean carbon chemistry is changing rapidly. Partial pressures of carbon dioxide gas (pCO2) are rising, pH levels are declining, and the ocean's buffer capacity is eroding. Regional differences in short-term pH trends primarily have been attributed to physical and biological processes; however, heterogeneous seawater carbonate chemistry may also be playing an important role. Here we use Surface Ocean CO2 Atlas Version 4 data to develop 12 month gridded climatologies of carbonate system variables and explore the coherent spatial patterns of ocean acidification and attenuation in the ocean carbon sink caused by rising atmospheric pCO2. High-latitude regions exhibit the highest pH and buffer capacity sensitivities to pCO2 increases, while the equatorial Pacific is uniquely insensitive due to a newly defined aqueous CO2 concentration effect. Importantly, dissimilar regional pH trends do not necessarily equate to dissimilar acidity ([H+]) trends, indicating that [H+] is a more useful metric of acidification.
Seasonal asymmetry in the evolution of surface ocean pCO2 and pH thermodynamic drivers and the influence on sea‐air CO2 flux

(John Wiley & Sons, 2018-10-11) Fassbender, Andrea ; Rodgers, Keith B. ; Palevsky, Hilary I. ; Sabine, Christopher L.

It has become clear that anthropogenic carbon invasion into the surface ocean drives changes in the seasonal cycles of carbon dioxide partial pressure (pCO2) and pH. However, it is not yet known whether the resulting sea‐air CO2 fluxes are symmetric in their seasonal expression. Here we consider a novel application of observational constraints and modeling inferences to test the hypothesis that changes in the ocean's Revelle factor facilitate a seasonally asymmetric response in pCO2 and the sea‐air CO2 flux. We use an analytical framework that builds on observed sea surface pCO2 variability for the modern era and incorporates transient dissolved inorganic carbon concentrations from an Earth system model. Our findings reveal asymmetric amplification of pCO2 and pH seasonal cycles by a factor of two (or more) above preindustrial levels under Representative Concentration Pathway 8.5. These changes are significantly larger than observed modes of interannual variability and are relevant to climate feedbacks associated with Revelle factor perturbations. Notably, this response occurs in the absence of changes to the seasonal cycle amplitudes of dissolved inorganic carbon, total alkalinity, salinity, and temperature, indicating that significant alteration of surface pCO2 can occur without modifying the physical or biological ocean state. This result challenges the historical paradigm that if the same amount of carbon and nutrients is entrained and subsequently exported, there is no impact on anthropogenic carbon uptake. Anticipation of seasonal asymmetries in the sea surface pCO2 and CO2 flux response to ocean carbon uptake over the 21st century may have important implications for carbon cycle feedbacks.
Global perspectives on observing ocean boundary current systems

(Frontiers Media, 2019-08-08) Todd, Robert E. ; Chavez, Francisco P. ; Clayton, Sophie A. ; Cravatte, Sophie ; Goes, Marlos Pereira ; Graco, Michelle ; Lin, Xiaopei ; Sprintall, Janet ; Zilberman, Nathalie ; Archer, Matthew ; Arístegui, Javier ; Balmaseda, Magdalena A. ; Bane, John M. ; Baringer, Molly O. ; Barth, John A. ; Beal, Lisa M. ; Brandt, Peter ; Calil, Paulo H. R. ; Campos, Edmo ; Centurioni, Luca R. ; Chidichimo, Maria Paz ; Cirano, Mauro ; Cronin, Meghan F. ; Curchitser, Enrique N. ; Davis, Russ E. ; Dengler, Marcus ; deYoung, Brad ; Dong, Shenfu ; Escribano, Ruben ; Fassbender, Andrea ; Fawcett, Sarah E. ; Feng, Ming ; Goni, Gustavo J. ; Gray, Alison R. ; Gutiérrez, Dimitri ; Hebert, Dave ; Hummels, Rebecca ; Ito, Shin-ichi ; Krug, Marjolaine ; Lacan, Francois ; Laurindo, Lucas ; Lazar, Alban ; Lee, Craig M. ; Lengaigne, Matthieu ; Levine, Naomi M. ; Middleton, John ; Montes, Ivonne ; Muglia, Michael ; Nagai, Takeyoshi ; Palevsky, Hilary I. ; Palter, Jaime B. ; Phillips, Helen E. ; Piola, Alberto R. ; Plueddemann, Albert J. ; Qiu, Bo ; Rodrigues, Regina ; Roughan, Moninya ; Rudnick, Daniel L. ; Rykaczewski, Ryan R. ; Saraceno, Martin ; Seim, Harvey E. ; Sen Gupta, Alexander ; Shannon, Lynne ; Sloyan, Bernadette M. ; Sutton, Adrienne J. ; Thompson, LuAnne ; van der Plas, Anja K. ; Volkov, Denis L. ; Wilkin, John L. ; Zhang, Dongxiao ; Zhang, Linlin

Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations.
Nutrient and chlorophyll analyses from surface samples collected underway on board container ships during basin-wide transects of the North Pacific Ocean from Hong Kong to Long Beach, CA from 2009-2012

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-07-06) Palevsky, Hilary I. ; Quay, Paul

Surface nutrient and chlorophyll analyses were performed on samples collected on board commercial container ships from April 2009 through December 2012. Samples were collected from the underway seawater system during basin-wide transects of the North Pacific Ocean while traversing from Hong Kong to Long Beach, California. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/829141

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