Jana Härri


Last Name

Härri

First Name

Jana

ORCID

0000-0002-1920-3372

Organisational unit

03731 - Gruber, Nicolas / Gruber, Nicolas

Filters

2023 - 20246
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Publications 1 - 6 of 6
  • Nitrogen loss processes in the Oxygen Minimum Zones of the Eastern Pacific
    Item type: Other Conference Item
    Härri, Jana (2023)
    15th IBP PhD Congress Booklet
  • Preface: Special Issue on Probing the Open Ocean With the Research Sailing Yacht Eugen Seibold for Climate Geochemistry
    Item type: Other Journal Item
    Schiebel, Ralf; Aardema, Hedy M.; Calleja, Maria Ll.; et al. (2024)
    Journal of Geophysical Research: Atmospheres
    The 72-foot sailing yacht Eugen Seibold is a new research platform for contamination-free sampling of the water column and atmosphere for biological, chemical, and physical properties, and the exchange processes between the two realms. Ultimate goal of the project is a better understanding of the modern and past ocean and climate. Operations started in 2019 in the Northeast Atlantic, and will focus on the Tropical Eastern Pacific from 2023 until 2025. Laboratories for air and seawater analyses are equipped with down-sized and automated state-of-the-art technology for a comprehensive description of the marine carbon system including CO2 concentration in the air and sea surface, pH, macro-, and micro-nutrient concentration (e.g., Fe, Cd), trace metals, and calcareous plankton. Air samples are obtained from ca. 13 m above sea surface and analyzed for particles (incl. black carbon and aerosols) and greenhouse gases. Plankton nets and seawater probes are deployed over the custom-made A-frame at the stern of the boat. Near Real-Time Transfer of underway data via satellite connection allows dynamic expedition planning to maximize gain of information. Data and samples are analyzed in collaboration with the international expert research community. Quality controlled data are published for open access. The entire suite of data facilitates refined proxy calibration of paleoceanographic and paleoclimate archives at high temporal and spatial resolution in relation to seawater and atmospheric parameters.
  • The impact of ENSO on the nitrous oxide dynamics in the Eastern Tropical Pacific
    Item type: Conference Poster
    Härri, Jana (2024)
  • Impact of ENSO on Nitrous Oxide Production and Emission in the Eastern Tropical Pacific
    Item type: Other Conference Item
    Härri, Jana; Bianchi, Daniele; Vogt, Meike; et al. (2024)
    Ocean Sciences Meeting 2024 Online Program
  • Interannual Variability of Marine Nitrogen Fixation in the Western Tropical Atlantic
    Item type: Journal Article
    Härri, Jana; Louchard, Domitille; Gruber, Nicolas (2024)
    Global Biogeochemical Cycles
    N₂ fixation is a central process of the marine nitrogen cycle, yet little is known about how this process varies from year-to-year. Here, we investigate this variability in the Western Tropical Atlantic (WTA), a region where N₂ fixation is prevalent, fueled, in part, by the nutrient input from the Amazon River. We use hindcast simulations from 1983 through 2019 with the Regional Oceanic Modeling System (ROMS) coupled to the Biogeochemical Elemental Cycling (BEC) model expanded to include Diatom-Diazotroph Assemblages (DDAs). Throughout the WTA, we find a substantial level of interannual variability of N₂ fixation, altering it by up to 33%, and locally by up to nearly 60%. Part of this interannual variability is driven by variations in the Amazon River discharge, which during high discharge events leads to reduced rates in the upper parts of the plume and strongly enhanced rates in the downstream part. This dipole pattern is a consequence of the riverine inputs of phosphorus and the competition with non-diazotrophs for this limiting resource. Another part of the N₂ fixation variability is driven by the Atlantic Meridional Mode (AMM), and the El Niño-Southern Oscillation (ENSO). These processes alter N₂ fixation primarily through the supply of the limiting nutrients phosphorus and iron by vertical mixing, while the role of top-down control through grazing is relatively limited in our model. The high, and so far not well recognized interannual N₂ fixation variability can lead to erroneous extrapolation of field measurements and inaccuracies in the marine nitrogen budget, if unaccounted for.
  • Nitrous oxide (N2O) dynamics in the Eastern Tropical Pacific
    Item type: Presentation
    Härri, Jana (2023)
Publications 1 - 6 of 6