Response of biological production and air-sea CO2 fluxes to upwelling intensification in the California and Canary Current Systems

Zouhair Lachkhar, Nicolas Gruber

    Research output: Contribution to journalArticle

    Abstract

    Upwelling-favorable winds have increased in most Eastern Boundary Upwelling Systems (EBUS) in the last decades, and it is likely that they increase further in response to global climate change. Here, we explore the response of biological production and air-sea CO2 fluxes to upwelling intensification in two of the four major EBUS, namely the California Current System (California CS) and Canary Current System (Canary CS). To this end, we use eddy-resolving regional ocean models on the basis of the Regional Oceanic Modeling System (ROMS) to which we have coupled a NPZD-type ecosystem model and a biogeochemistry module describing the carbon cycle and subject these model configurations to an idealized increase in the wind stress. We find that a doubling of the wind-stress doubles net primary production (NPP) in the southern California CS and central and northern Canary CS, while it leads to an increase of less than 50% in the central and northern California CS as well as in the southern Canary CS. This differential response is a result of i) different nutrient limitation states with higher sensitivity to upwelling intensification in regions where nutrient limitation is stronger and ii) more efficient nutrient assimilation by biology in the Canary CS relative to the California CS because of a faster nutrient-replete growth rate and longer nearshore water residence times. In the regions where production increases commensurably with upwelling intensification, the enhanced net biological uptake of CO2 compensates the increase in upwelling driven CO2 outgassing, resulting in only a small change in the biological pump efficiency and hence in a small sensitivity of air-sea CO2 fluxes to upwelling intensification. In contrast, in the central California CS as well as in the southern Canary CS around Cape Blanc, the reduced biological efficiency enhances the CO2 outgassing and leads to a substantial sensitivity of the air-sea CO2 fluxes to upwelling intensification.

    Original languageEnglish (US)
    Pages (from-to)149-160
    Number of pages12
    JournalJournal of Marine Systems
    Volume109-110
    DOIs
    StatePublished - Jan 1 2013

    Fingerprint

    biological production
    canaries
    upwelling
    carbon dioxide
    air
    system boundary
    nutrients
    nutrient limitation
    wind stress
    biogeochemistry
    pumps
    biological pump
    biological uptake
    sea
    primary productivity
    assimilation (physiology)
    nutrient
    oceans
    net primary production
    climate change

    Keywords

    • Air-sea CO exchange
    • Biological production
    • California Current System
    • Canary Current System
    • Eastern Boundary Upwelling Systems
    • Upwelling intensification

    ASJC Scopus subject areas

    • Oceanography
    • Ecology, Evolution, Behavior and Systematics
    • Aquatic Science

    Cite this

    Response of biological production and air-sea CO2 fluxes to upwelling intensification in the California and Canary Current Systems. / Lachkhar, Zouhair; Gruber, Nicolas.

    In: Journal of Marine Systems, Vol. 109-110, 01.01.2013, p. 149-160.

    Research output: Contribution to journalArticle

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