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1. Comparison of bacterial carbon production estimates from dilution and 3H ‐leucine methods across a strong gradient in ocean productivity

   https://doi.org/10.1002/lom3.10546  

   Landry, Michael R. ; Rivera, Sara R. ; Stukel, Michael R. ; Selph, Karen E. ( April 2023 , Limnology and Oceanography: Methods)

   The uptake of³H‐labeled leucine into proteins, a widely used method for estimating bacterial carbon production (BCP), is suggested to underestimate or overestimate bacterial growth in the open ocean by a factor of 40 uncertainty. Meanwhile, an alternative BCP approach, by the dilution method, has untested concerns about potential overestimation of bacterial growth from dissolved substrates released by filtration. We compared BCP_Diland BCP_Leuestimates from three cruises across a broad trophic gradient, from offshore oligotrophy to coastal upwelling, in the California Current Ecosystem. Our initial analyses based on midday microscopical estimates of bacterial size and a priori assumptions of conversions relationships revealed a mean two‐fold difference in BCP estimates (BCP_Dilhigher), but no systematic bias between low and high productivity stations. BCP_Diland BCP_Leuboth demonstrated strong relationships with bacteria cell abundance. Reanalysis of results, involving a different cell carbon‐biovolume relationship and informed by forward angle light scatter from flow cytometry as a relative cell size index, demonstrated that BCP_Diland BCP_Leuare fully compatible, with a 1 : 1 fit for bacteria of 5 fg C cell⁻¹. Based on these results and considering different strengths of the methods, the combined use of³H‐labeled leucine and dilution techniques provide strong mutually supportive constraints on bacterial biomass and production.

    

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2. A database of ocean primary productivity from the 14C method

   https://doi.org/10.1002/lol2.10175  

   Marra, J. F. ; Barber, R. T. ; Barber, E. ; Bidigare, R. R. ; Chamberlin, W. S. ; Goericke, R. ; Hargreaves, B. R. ; Hiscock, M. ; Iturriaga, R. ; Johnson, Z. I. ; et al ( November 2020 , Limnology and Oceanography Letters)

   The database on ocean primary productivity comprises over two decades (1985–2008) of data that the authors have participated in collecting, using the assimilation of inorganic¹⁴C through photosynthesis, in incubations carried out in situ. The dataset is perhaps unique in that it uses, overwhelmingly, consistent methodology while covering a wide geographic range. Ancillary data are included. Using the database, it is hoped that investigators can test for the relationships among the environmental drivers for ocean productivity, the meaning of the¹⁴C method in terms of phytoplankton physiology and the dynamics in the water column, and as a resource for further development of productivity algorithms using satellite ocean color imagery.

    

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3. FluxSat: Measuring the Ocean–Atmosphere Turbulent Exchange of Heat and Moisture from Space

   https://doi.org/10.3390/rs12111796  

   Gentemann, Chelle L. ; Clayson, Carol Anne ; Brown, Shannon ; Lee, Tong ; Parfitt, Rhys ; Farrar, J. Thomas ; Bourassa, Mark ; Minnett, Peter J. ; Seo, Hyodae ; Gille, Sarah T. ; et al ( June 2020 , Remote Sensing)

   null (Ed.)

   Recent results using wind and sea surface temperature data from satellites and high-resolution coupled models suggest that mesoscale ocean–atmosphere interactions affect the locations and evolution of storms and seasonal precipitation over continental regions such as the western US and Europe. The processes responsible for this coupling are difficult to verify due to the paucity of accurate air–sea turbulent heat and moisture flux data. These fluxes are currently derived by combining satellite measurements that are not coincident and have differing and relatively low spatial resolutions, introducing sampling errors that are largest in regions with high spatial and temporal variability. Observational errors related to sensor design also contribute to increased uncertainty. Leveraging recent advances in sensor technology, we here describe a satellite mission concept, FluxSat, that aims to simultaneously measure all variables necessary for accurate estimation of ocean–atmosphere turbulent heat and moisture fluxes and capture the effect of oceanic mesoscale forcing. Sensor design is expected to reduce observational errors of the latent and sensible heat fluxes by almost 50%. FluxSat will improve the accuracy of the fluxes at spatial scales critical to understanding the coupled ocean–atmosphere boundary layer system, providing measurements needed to improve weather forecasts and climate model simulations. 

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4. Ocean carbon from space: Current status and priorities for the next decade

   https://doi.org/10.1016/j.earscirev.2023.104386  

   Brewin, Robert J.W. ; Sathyendranath, Shubha ; Kulk, Gemma ; Rio, Marie-Hélène ; Concha, Javier A. ; Bell, Thomas G. ; Bracher, Astrid ; Fichot, Cédric ; Frölicher, Thomas L. ; Galí, Martí ; et al ( May 2023 , Earth-Science Reviews)
5. Strong glacial-interglacial variability in upper ocean hydrodynamics, biogeochemistry, and productivity in the southern Indian Ocean

   https://doi.org/10.1038/s43247-021-00148-0  

   Tangunan, Deborah ; Berke, Melissa A. ; Cartagena-Sierra, Alejandra ; Flores, José Abel ; Gruetzner, Jens ; Jiménez-Espejo, Francisco ; LeVay, Leah J. ; Baumann, Karl-Heinz ; Romero, Oscar ; Saavedra-Pellitero, Mariem ; et al ( December 2021 , Communications Earth & Environment)

   null (Ed.)

   Abstract In the southern Indian Ocean, the position of the subtropical front – the boundary between colder, fresher waters to the south and warmer, saltier waters to the north – has a strong influence on the upper ocean hydrodynamics and biogeochemistry. Here we analyse a sedimentary record from the Agulhas Plateau, located close to the modern position of the subtropical front and use alkenones and coccolith assemblages to reconstruct oceanographic conditions over the past 300,000 years. We identify a strong glacial-interglacial variability in sea surface temperature and productivity associated with subtropical front migration over the Agulhas Plateau, as well as shorter-term high frequency variability aligned with variations in high latitude insolation. Alkenone and coccolith abundances, in combination with diatom and organic carbon records indicate high glacial export productivity. We conclude that the biological pump was more efficient and strengthened during glacial periods, which could partly account for the reported reduction in atmospheric carbon dioxide concentrations. 

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