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2. Assessment of oceanographic conditions during the North Atlantic EXport processes in the ocean from RemoTe sensing (EXPORTS) field campaign

Author

Johnson, Leah, Siegel, David A., Thompson, Andrew F., Fields, Erik, Erickson, Zachary K., Cetinic, Ivona, Lee, Craig M., D'Asaro, Eric A., Nelson, Norman B., Omand, Melissa M., Sten, Michaela, Traylor, Shawnee, Nicholson, David P., Graff, Jason R., Steinberg, Deborah K., Sosik, Heidi M., Buesseler, Ken O., Brzezinski, Mark A., Ramos, Inia Soto, Carvalho, Filipa, and Henson, Stephanie A.

Published
2024
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6. Elevated pCO2 enhances bacterioplankton removal of organic carbon.

Author

James, Anna K, Passow, Uta, Brzezinski, Mark A, Parsons, Rachel J, Trapani, Jennifer N, and Carlson, Craig A

Subjects
Humans, Phytoplankton, Cyanobacteria, Carbon Dioxide, Carbon, Water Microbiology, Ecosystem, Seawater, Environmental Monitoring, Oceans and Seas, General Science & Technology
Abstract

Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000-1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 -~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean.

Published
2017

7. Dynamics of Aggregates and Sinking Carbon Fluxes in a Turbulent Ocean

Author

Siegel, David, Burd, Adrian, Estapa, Margaret, Fields, Erik, Johnson, Leah, Romanelli, Elisa, Brzezinski, Mark, Buesseler, Ken, Clevenger, Samantha, Cetinic, Ivona, Drago, Laetitia, Durkin, Colleen, Kiko, Rainer, Kramer, Sasha, Maas, Amy, Omand, Melissa, Passow, Uta, Steinberg, Deborah, Siegel, David, Burd, Adrian, Estapa, Margaret, Fields, Erik, Johnson, Leah, Romanelli, Elisa, Brzezinski, Mark, Buesseler, Ken, Clevenger, Samantha, Cetinic, Ivona, Drago, Laetitia, Durkin, Colleen, Kiko, Rainer, Kramer, Sasha, Maas, Amy, Omand, Melissa, Passow, Uta, and Steinberg, Deborah

Abstract

The sinking of particulate matter from the upper ocean dominates the export and sequestration of organic carbon by the biological pump, a critical component of the Earth's carbon cycle. Controls on carbon export are thought to be driven by ecological processes that produce and repackage sinking biogenic particles. Here, we present observations during the demise of the Northeast Atlantic Ocean spring bloom illustrating the importance of storm-induced turbulence on the dynamics of sinking particles. A sequence of four large storms caused upper layer mean turbulence levels to vary by more than three orders of magnitude. Large particle (>0.1 to 10 mm) abundance and size changed accordingly: increasing via shear coagulation when turbulence was moderate and decreasing rapidly when turbulence was intense due to shear disaggregation. Particle export was also tied to storm forcing as large particles were mixed to depth during mixed layer deepening. After the mixed layer shoaled, these particles, now isolated from intense surface mixing, grew larger and subsequently sank. This sequence of events matched the timing of sinking particle flux observations. Particle export was influenced by increases in aggregate abundance and porosity, which appeared to be enhanced by the repeated creation and destruction of aggregates. Last, particle transit efficiency through the mesopelagic zone was reduced by presumably biotic processes that created small particles (<0.5 mm) from larger ones. Our results demonstrate that ocean turbulence significantly impacts the nature and dynamics of sinking particles, strongly influencing particle export and the efficiency of the biological pump.

Published
2024
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9. Size‐Fractionated Primary Production Dynamics During the Decline Phase of the North Atlantic Spring Bloom.

Author

Meyer, Meredith G., Brzezinski, Mark A., Cohn, Melanie R., Kramer, Sasha J., Paul, Nicola, Sharpe, Garrett, Niebergall, Alexandria K., Gifford, Scott, Cassar, Nicolas, and Marchetti, Adrian

Subjects
SPRING, ALGAL blooms, SILICIC acid, PHYTOPLANKTON, NUTRIENT cycles, ECOSYSTEM dynamics, FRESHWATER phytoplankton
Abstract

The North Atlantic is a region of enhanced biogeochemical and climatological importance for the global ocean as it is the site of one of the largest seasonal phytoplankton blooms on the planet. However, there is a lack of understanding of how phytoplankton size influences bloom dynamics and associated nutrient utilization rates, particularly during the decline phase when export to the deep ocean is especially pronounced. Here, we evaluate trends in size‐fractionated carbon, nitrogen, and silicic acid uptake rates in conjunction with environmental parameters to assess these dynamics. In our study, the decline phase of the bloom continued to be highly productive with net primary production (NPP) ranging from 36.4 to 146.6 mmol C m−2 d−1 and approximately 54% of primary production being driven by large phytoplankton cells (≥5 μm) that were primarily utilizing nitrate (mean f‐ratio of 0.77). Entrainment of silicic acid related to deepening of the mixed layer caused by storms increased silicic acid uptake rates to 2.0–5.7 mmol Si m−2 d−1 without concomitant increases in NPP by large cells (silicic acid to carbon uptake ratios averaged 0.12). A companion study in the North Pacific allowed for paired evaluation of these regions. Our results suggest that in highly productive regions where phytoplankton biomass and productivity is distributed across a broad range of cell sizes, such as the North Atlantic, size itself has a stronger influence on nutrient cycling and potential carbon export relative to regions with lower production and a predominance of small (<5 μm) cells, such as the North Pacific. Plain Language Summary: The North Atlantic Ocean experiences a seasonal bloom of phytoplankton. This bloom represents one of the largest removals of anthropogenic carbon to the deep ocean on the planet. Here, we seek to better quantify the mechanisms of this removal by characterizing the amount and composition of phytoplankton present and how much primary production they are engaging in. We sampled during the decline phase of the spring bloom and found the region to be characterized by mostly large phytoplankton primarily utilizing nitrate. When compared to a companion study in the North Pacific, this study confirms the important role cell size and nutrient availability play in determining the degree of productivity in both high and low primary production oceanic regions. Key Points: The decline phase of the North Atlantic spring bloom exhibits transitions in the balance between small and large size‐fractionated primary production dynamicsDuring the bloom decline, diatoms contribute less to primary production but remain a substantial component of phytoplankton biomassPhytoplankton size is a substantial control on ecosystem dynamics in endmember oceanic productivity‐export systems [ABSTRACT FROM AUTHOR]

Published
2024
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10. Physical Mechanisms Sustaining Silica Production Following the Demise of the Diatom Phase of the North Atlantic Spring Phytoplankton Bloom During EXPORTS.

Author

Brzezinski, Mark A., Johnson, Leah, Estapa, Margaret, Clevenger, Samantha, Roca‐Martí, Montserrat, Romanelli, Elisa, Buck, Kristen N., Jenkins, Bethany D., and Jones, Janice L.

Subjects
ALGAL blooms, DIATOMS, SPRING, SILICIC acid, DIATOM frustules, PHAEODACTYLUM tricornutum, CARBON sequestration, SILICA
Abstract

Each spring, the North Atlantic experiences one of the largest open‐ocean phytoplankton blooms in the global ocean. Diatoms often dominate the initial phase of the bloom with succession driven by exhaustion of silicic acid. The North Atlantic was sampled over 3.5 weeks in spring 2021 following the demise of the main diatom bloom, allowing mechanisms that sustain continued diatom contributions to be examined. Diatom biomass was initially relatively high with biogenic silica concentrations up to 2.25 μmol Si L−1. A low initial silicic acid concentration of 0.1–0.3 μM imposed severe Si limitation of silica production and likely limited the diatom growth rate. Four storms over the next 3.5 weeks entrained silicic acid into the mixed layer, relieving growth limitation, but uptake limitation persisted. Silica production was modest and dominated by the >5.0 μm size fraction although specific rates were highest in the 0.6–5.0 μm size fraction over most of the cruise. Silica dissolution averaged 68% of silica production. The resupply of silicic acid via storm entrainment and silica dissolution supported a cumulative post‐bloom silica production that was 32% of that estimated during the main bloom event. Diatoms contributed significantly to new and to primary production after the initial bloom, possibly dominating both. Diatom contribution to organic‐carbon export was also significant at 40%–70%. Thus, diatoms can significantly contribute to regional biogeochemistry following initial silicic acid depletion, but that contribution relies on physical processes that resupply the nutrient to surface waters. Plain Language Summary: Each spring, one of the largest phytoplankton blooms in the global ocean occurs in the North Atlantic Ocean. One group of phytoplankton, the diatoms, often dominates the early bloom. Diatoms are unique among the phytoplankton as they require the element silicon to construct their cell walls. Dissolved silicon is in relatively short supply in the North Atlantic, prompting this study of how the availability of silicic acid controls the contribution of diatoms to the bloom. At the start of our expedition, extremely low silicic acid concentrations in surface waters indicated that a diatom bloom had already occurred. Experiments revealed strong silicon limitation of the remaining diatoms. A series of four storms over 3 weeks introduced pulses of silicic acid to surface waters partially alleviating Si limitation. As a result, diatoms were able to significantly contribute to primary productivity and to the export of organic carbon despite persistent silicon limitation. The results indicate that diatoms can play a significant biogeochemical role in the North Atlantic bloom following the initial depletion of silicic acid, but their contribution is regulated by physical processes that resupply the nutrient to surface waters. Such processes may enhance overall bloom productivity and its contribution to carbon sequestration. Key Points: The diatom phase of the North Atlantic spring bloom terminated due to silicon limitationPhysical processes that reintroduced silicic acid sustained post‐bloom diatom net productivityThe resupply of silicic acid allowed Si‐limited diatoms to contribute significantly to primary production and to organic carbon export [ABSTRACT FROM AUTHOR]

Published
2024
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12. Assessment of Oceanographic Conditions during the North Atlantic EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) Field Campaign

Author

Johnson, Leah, primary, Siegel, David A., additional, Thompson, Andrew F., additional, Fields, Erik, additional, Erickson, Zachary, additional, Cetinic, Ivona, additional, Lee, Craig M., additional, D'Asaro, Eric, additional, Nelson, Norman B., additional, Omand, Melissa, additional, Sten, Michaela, additional, Traylor, Shawnee, additional, Nicholson, David, additional, Graff, Jason R., additional, Steinberg, Deborah, additional, Sosik, Heidi M., additional, Buesseler, Ken, additional, Brzezinski, Mark, additional, Soto Ramos, Inia, additional, Carvalho, Filipa, additional, and Henson, Stephanie, additional

Published
2023
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15. Enhanced silica ballasting from iron stress sustains carbon export in a frontal zone within the California Current

Author

Brzezinski, Mark A, Krause, Jeffrey W, Bundy, Randelle M, Barbeau, Katherine A, Franks, Peter, Goericke, Ralf, Landry, Michael R, and Stukel, Michael R

Subjects
Geophysics, Oceanography, Physical Geography and Environmental Geoscience
Abstract

Nutrient dynamics, phytoplankton rate processes, and export were examined in a frontal region between an anticyclone and a pair of cyclones 120 km off the coast in the southern California Current System (sCCS). Low silicic acid: nitrate ratios (Si:N) and high nitrate to iron ratios (N:Fe) characteristic of Fe-limiting conditions in the sCCS were associated with the northern cyclone and with the transition zone between the cyclones and the anticyclone. Phytoplankton growth in low-Si:N, high-N:Fe waters responded strongly to added Fe, confirming growth limitation by Fe of the diatom-dominated phytoplankton community. Low Si:N waters had low biogenic silica content, intermediate productivity, but high export compared to intermediate Si:N waters indicating increased export efficiency under Fe stress. Biogenic silica and particulate organic carbon (POC) export were both high beneath low Si:N waters with biogenic silica export being especially enhanced. This suggests that relatively high POC export from low Si:N waters was supported by silica ballasting from Fe-limited diatoms. Higher POC export efficiency in low Si:N waters may have been further enhanced by lower rates of organic carbon remineralization due to reduced grazing of more heavily armored diatoms growing under Fe stress. The results imply that Fe stress can enhance carbon export, despite lowering productivity, by driving higher export efficiency.

Published
2015

16. Variability in diatom contributions to biomass, organic matter production and export across a frontal gradient in the California Current Ecosystem

Author

Krause, Jeffrey W, Brzezinski, Mark A, Goericke, Ralf, Landry, Michael R, Ohman, Mark D, Stukel, Michael R, and Taylor, Andrew G

Subjects
Geophysics, Oceanography, Physical Geography and Environmental Geoscience
Abstract

In the offshore waters of Southern California, submesoscale processes associated with fronts may stimulate phytoplankton blooms and lead to biomass shifts at multiple trophic levels. Here we report the results of a study on the cycling of biogenic silica (bSiO2) with estimates of the contributions of diatoms to primary and new production in water masses adjacent to (i.e., coastal or oceanic) and within an offshore front in the Southern California Current Ecosystem (CCE). The coastal and oceanic water were sampled in cyclonic and anticyclonic eddies, respectively, with the frontal water being an interaction region between the eddy types. Concentrations of bSiO2 varied by 25-fold across the front, with concentrations in frontal waters 20-25% of those in coastal waters. Rates of biogenic silica production spanned an equally large range, with rates within the frontal region that were half those in the coastal regions. Contributions of diatoms to primary and new production were disproportionately higher than their contribution to autotrophic biomass in all areas, ranging from 5-8%, 19-30%, and 32-43% for both processes in the oceanic, frontal and coastal waters, respectively. Across the frontal area, diatoms could account for

Published
2015

20. The GEOTRACES Intermediate Data Product 2017

Author

Schlitzer, Reiner, Anderson, Robert F., Dodas, Elena Masferrer, Lohan, Maeve, Geibert, Walter, Tagliabue, Alessandro, Bowie, Andrew, Jeandel, Catherine, Maldonado, Maria T., Landing, William M., Cockwell, Donna, Abadie, Cyril, Abouchami, Wafa, Achterberg, Eric P., Agather, Alison, Aguliar-Islas, Ana, van Aken, Hendrik M., Andersen, Morten, Archer, Corey, Auro, Maureen, de Baar, Hein J., Baars, Oliver, Baker, Alex R., Bakker, Karel, Basak, Chandranath, Baskaran, Mark, Bates, Nicholas R., Bauch, Dorothea, van Beek, Pieter, Behrens, Melanie K., Black, Erin, Bluhm, Katrin, Bopp, Laurent, Bouman, Heather, Bowman, Katlin, Bown, Johann, Boyd, Philip, Boye, Marie, Boyle, Edward A., Branellec, Pierre, Bridgestock, Luke, Brissebrat, Guillaume, Browning, Thomas, Bruland, Kenneth W., Brumsack, Hans-Jürgen, Brzezinski, Mark, Buck, Clifton S., Buck, Kristen N., Buesseler, Ken, Bull, Abby, Butler, Edward, Cai, Pinghe, Mor, Patricia Cámara, Cardinal, Damien, Carlson, Craig, Carrasco, Gonzalo, Casacuberta, Núria, Casciotti, Karen L., Castrillejo, Maxi, Chamizo, Elena, Chance, Rosie, Charette, Matthew A., Chaves, Joaquin E., Cheng, Hai, Chever, Fanny, Christl, Marcus, Church, Thomas M., Closset, Ivia, Colman, Albert, Conway, Tim M., Cossa, Daniel, Croot, Peter, Cullen, Jay T., Cutter, Gregory A., Daniels, Chris, Dehairs, Frank, Deng, Feifei, Dieu, Huong Thi, Duggan, Brian, Dulaquais, Gabriel, Dumousseaud, Cynthia, Echegoyen-Sanz, Yolanda, Edwards, R. Lawrence, Ellwood, Michael, Fahrbach, Eberhard, Fitzsimmons, Jessica N., Russell Flegal, A., Fleisher, Martin Q., van de Flierdt, Tina, Frank, Martin, Friedrich, Jana, Fripiat, Francois, Fröllje, Henning, Galer, Stephen J.G., Gamo, Toshitaka, Ganeshram, Raja S., Garcia-Orellana, Jordi, Garcia-Solsona, Ester, Gault-Ringold, Melanie, George, Ejin, Gerringa, Loes J.A., Gilbert, Melissa, Godoy, Jose M., Goldstein, Steven L., Gonzalez, Santiago R., Grissom, Karen, Hammerschmidt, Chad, Hartman, Alison, Hassler, Christel S., Hathorne, Ed C., Hatta, Mariko, Hawco, Nicholas, Hayes, Christopher T., Heimbürger, Lars-Eric, Helgoe, Josh, Heller, Maija, Henderson, Gideon M., Henderson, Paul B., van Heuven, Steven, Ho, Peng, Horner, Tristan J., Hsieh, Yu-Te, Huang, Kuo-Fang, Humphreys, Matthew P., Isshiki, Kenji, Jacquot, Jeremy E., Janssen, David J., Jenkins, William J., John, Seth, Jones, Elizabeth M., Jones, Janice L., Kadko, David C., Kayser, Rick, Kenna, Timothy C., Khondoker, Roulin, Kim, Taejin, Kipp, Lauren, Klar, Jessica K., Klunder, Maarten, Kretschmer, Sven, Kumamoto, Yuichiro, Laan, Patrick, Labatut, Marie, Lacan, Francois, Lam, Phoebe J., Lambelet, Myriam, Lamborg, Carl H., Le Moigne, Frédéric A.C., Le Roy, Emilie, Lechtenfeld, Oliver J., Lee, Jong-Mi, Lherminier, Pascale, Little, Susan, López-Lora, Mercedes, Lu, Yanbin, Masque, Pere, Mawji, Edward, Mcclain, Charles R., Measures, Christopher, Mehic, Sanjin, Barraqueta, Jan-Lukas Menzel, van der Merwe, Pier, Middag, Rob, Mieruch, Sebastian, Milne, Angela, Minami, Tomoharu, Moffett, James W., Moncoiffe, Gwenaelle, Moore, Willard S., Morris, Paul J., Morton, Peter L., Nakaguchi, Yuzuru, Nakayama, Noriko, Niedermiller, John, Nishioka, Jun, Nishiuchi, Akira, Noble, Abigail, Obata, Hajime, Ober, Sven, Ohnemus, Daniel C., van Ooijen, Jan, O'Sullivan, Jeanette, Owens, Stephanie, Pahnke, Katharina, Paul, Maxence, Pavia, Frank, Pena, Leopoldo D., Peters, Brian, Planchon, Frederic, Planquette, Helene, Pradoux, Catherine, Puigcorbé, Viena, Quay, Paul, Queroue, Fabien, Radic, Amandine, Rauschenberg, S., Rehkämper, Mark, Rember, Robert, Remenyi, Tomas, Resing, Joseph A., Rickli, Joerg, Rigaud, Sylvain, Rijkenberg, Micha J.A., Rintoul, Stephen, Robinson, Laura F., Roca-Martí, Montserrat, Rodellas, Valenti, Roeske, Tobias, Rolison, John M., Rosenberg, Mark, Roshan, Saeed, Rutgers van der Loeff, Michiel M., Ryabenko, Evgenia, Saito, Mak A., Salt, Lesley A., Sanial, Virginie, Sarthou, Geraldine, Schallenberg, Christina, Schauer, Ursula, Scher, Howie, Schlosser, Christian, Schnetger, Bernhard, Scott, Peter, Sedwick, Peter N., Semiletov, Igor, Shelley, Rachel, Sherrell, Robert M., Shiller, Alan M., Sigman, Daniel M., Singh, Sunil Kumar, Slagter, Hans A., Slater, Emma, Smethie, William M., Snaith, Helen, Sohrin, Yoshiki, Sohst, Bettina, Sonke, Jeroen E., Speich, Sabrina, Steinfeldt, Reiner, Stewart, Gillian, Stichel, Torben, Stirling, Claudine H., Stutsman, Johnny, Swarr, Gretchen J., Swift, James H., Thomas, Alexander, Thorne, Kay, Till, Claire P., Till, Ralph, Townsend, Ashley T., Townsend, Emily, Tuerena, Robyn, Twining, Benjamin S., Vance, Derek, Velazquez, Sue, Venchiarutti, Celia, Villa-Alfageme, Maria, Vivancos, Sebastian M., Voelker, Antje H.L., Wake, Bronwyn, Warner, Mark J., Watson, Ros, van Weerlee, Evaline, Alexandra Weigand, M., Weinstein, Yishai, Weiss, Dominik, Wisotzki, Andreas, Woodward, E. Malcolm S., Wu, Jingfeng, Wu, Yingzhe, Wuttig, Kathrin, Wyatt, Neil, Xiang, Yang, Xie, Ruifang C., Xue, Zichen, Yoshikawa, Hisayuki, Zhang, Jing, Zhang, Pu, Zhao, Ye, Zheng, Linjie, Zheng, Xin-Yuan, Zieringer, Moritz, Zimmer, Louise A., Ziveri, Patrizia, Zunino, Patricia, and Zurbrick, Cheryl

Published
2018
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26. The Genome of the Diatom Thalassiosira pseudonana: Ecology, Evolution, and Metabolism

Author

Armbrust, E. Virginia, Berges, John A., Bowler, Chris, Green, Beverley R., Martinez, Diego, Putnam, Nicholas H., Zhou, Shiguo, Allen, Andrew E., Apt, Kirk E., Bechner, Michael, Brzezinski, Mark A., Chaal, Balbir K., Chiovitti, Anthony, Davis, Aubrey K., Demarest, Mark S., Detter, J. Chris, Glavina, Tijana, Goodstein, David, Hadi, Masood Z., Hellsten, Uffe, Hildebrand, Mark, Jenkins, Bethany D., Jurka, Jerzy, Kapitonov, Vladimir V., Kröger, Nils, Lane, Todd W., Larimer, Frank W., Lippmeier, J. Casey, Lucas, Susan, Medina, Mónica, Montsant, Anton, Obornik, Miroslav, Parker, Micaela Schnitzler, Palenik, Brian, Pazour, Gregory J., Richardson, Paul M., Rynearson, Tatiana A., Saito, Mak A., Schwartz, David C., Thamatrakoln, Kimberlee, Valentin, Klaus, Vardi, Assaf, Wilkerson, Frances P., and Rokhsar, Daniel S.

Published
2004

27. Southern Ocean Iron Enrichment Experiment: Carbon Cycling in High- and Low-Si Waters

Author

Coale, Kenneth H., Johnson, Kenneth S., Chavez, Francisco P., Buesseler, Ken O., Barber, Richard T., Brzezinski, Mark A., Cochlan, William P., Millero, Frank J., Falkowski, Paul G., Bauer, James E., Wanninkhof, Rik H., Kudela, Raphael M., Altabet, Mark A., Hales, Burke E., Takahashi, Taro, Landry, Michael R., Bidigare, Robert R., Wang, Xiujun, Chase, Zanna, Strutton, Pete G., Friederich, Gernot E., Gorbunov, Maxim Y., Lance, Veronica P., Hilting, Anna K., Hiscock, Michael R., Demarest, Mark, Hiscock, William T., Sullivan, Kevin F., Tanner, Sara J., Gordon, R. Mike, Hunter, Craig N., Elrod, Virginia A., Fitzwater, Steve E., Jones, Janice L., Tozzi, Sasha, Koblizek, Michal, Roberts, Alice E., Herndon, Julian, Brewster, Jodi, Ladizinsky, Nicolas, Smith, Geoffrey, Cooper, David, Timothy, David, Brown, Susan L., Selph, Karen E., Sheridan, Cecelia C., Twining, Benjamin S., and Johnson, Zackary I.

Published
2004

37. Quantitative analysis of food web dynamics in a low export ecosystem

Author

McNair, Heather M, primary, Meyer, Meredith G, additional, Lerch, Sarah J, additional, Maas, Amy E, additional, Stephens, Brandon M, additional, Fox, James, additional, Buck, Kristen N, additional, Burns, Shannon M, additional, Cetinic, Ivona, additional, Cohn, Melanie R, additional, Durkin, Colleen, additional, Gifford, Scott M, additional, Gong, Weida, additional, Graff, Jason R, additional, Jenkins, Bethany, additional, Jones, Erin L, additional, Santoro, Alyson E, additional, Shea, Connor H, additional, Stamieszkin, Karen, additional, Steinberg, Deborah K, additional, Marchetti, Adrian, additional, Carlson, Craig A, additional, Menden-Deuer, Susanne, additional, Brzezinski, Mark A, additional, Siegel, David A, additional, and Rynearson, Tatiana A, additional

Published
2023
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39. Assessment of oceanographic conditions during the North Atlantic EXport processes in the ocean from RemoTe Sensing (EXPORTS) Field campaign

Author

Johnson, Leah, Siegel, David A., Thompson, Andrew F., Fields, Erik, Erickson, Zachary, Cetinic, Ivona, Lee, Craig M., D'Asaro, Eric, Nelson, Norman B., Omand, Melissa, Sten, Michaela, Traylor, Shawnee, Nicholson, David, Graff, Jason R., Steinberg, Deborah, Sosik, Heidi M., Buesseler, Ken, Brzezinski, Mark, Soto Ramos, Inia, Carvalho, Filipa, Henson, Stephanie, Johnson, Leah, Siegel, David A., Thompson, Andrew F., Fields, Erik, Erickson, Zachary, Cetinic, Ivona, Lee, Craig M., D'Asaro, Eric, Nelson, Norman B., Omand, Melissa, Sten, Michaela, Traylor, Shawnee, Nicholson, David, Graff, Jason R., Steinberg, Deborah, Sosik, Heidi M., Buesseler, Ken, Brzezinski, Mark, Soto Ramos, Inia, Carvalho, Filipa, and Henson, Stephanie

Abstract

This manuscript presents an overview of NASA’s EXport Processes in the Ocean from Remote Sensing 2021 Field Campaign in the North Atlantic (EXPORTS NA) and provides quantitative and dynamical descriptions of the physical processes modulating water transformations during the study. A major programmatic goal was to conduct the sampling in a Lagrangian mode so that ocean ecological and biogeochemical changes can be observed independent from physical advective processes. To accomplish this goal, EXPORTS NA conducted a multi-ship, multi-asset field sampling program within a retentive, anticyclonic mode water eddy. Beneath depths of ∼100 m, Lagrangian sampling assets remained within the eddy core waters (ECWs) throughout the experiment, demonstrating that the ECWs within the mode water eddy were retentive. However, strong westerly winds from four storm events deepened the mixed layer (ML) of the surface core waters (SCWs) above the eddy’s mode water core by 25-40 m and exchanged some of the SCWs with surface waters outside of the eddy via Ekman transport. Estimates of flushing times ranged from 5-8 days, with surface exchange fractions ranging from 20-75% and were consistent with particle tracking advected by combined geostrophic and Ekman velocities. The relative contributions of horizontal and vertical advection on changes in ECW tracers depended on the horizontal and vertical gradients of that tracer. For example, horizontal advection played a large role in ECW salinity fluxes, while vertical entrainment played a larger role in the fluxes of nutrients into SCW ML. Each storm injected nutrients and low oxygen waters into the ML, after which the surface ocean ecosystem responded by reducing nutrient concentrations and increasing %O2 saturation levels. Overall, ECW values of chlorophyll and POC were the largest at the onset of the field program and decreased throughout the campaign. The analysis presented provides a physical oceanographic context for the many measurements

Published
2023

42. Characterization of the molecular mechanisms of silicon uptake in coccolithophores

Author

Ratcliffe, Sarah, primary, Meyer, Erin M., additional, Walker, Charlotte E., additional, Knight, Michael, additional, McNair, Heather M., additional, Matson, Paul G., additional, Iglesias‐Rodriguez, Debora, additional, Brzezinski, Mark, additional, Langer, Gerald, additional, Sadekov, Aleksey, additional, Greaves, Mervyn, additional, Brownlee, Colin, additional, Curnow, Paul, additional, Taylor, Alison R., additional, and Wheeler, Glen L., additional

Published
2022
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