Publication Date:
2017-04-04
Description:
In this study a coupled ocean‐atmosphere model containing interactive marine
biogeochemistry is used to analyze interannual, lagged, and decadal marine biogeochemical
responses to the North Atlantic Oscillation (NAO), the dominant mode of North Atlantic
atmospheric variability. The coupled model adequately reproduces present‐day
climatologies and NAO atmospheric variability. It is shown that marine biogeochemical
responses to the NAO are governed by different mechanisms according to the time scale
considered. On interannual time scales, local changes in vertical mixing, caused by
modifications in air‐sea heat, freshwater, and momentum fluxes, are most relevant in
influencing phytoplankton growth through light and nutrient limitation mechanisms. At
subpolar latitudes, deeper mixing occurring during positive NAO winters causes a slight
decrease in late winter chlorophyll concentration due to light limitation and a 10%–20%
increase in spring chlorophyll concentration due to higher nutrient availability. The
lagged response of physical and biogeochemical properties to a high NAO winter shows
some memory in the following 2 years. In particular, subsurface nutrient anomalies
generated by local changes in mixing near the American coast are advected along the
North Atlantic Current, where they are suggested to affect downstream chlorophyll
concentration with 1 year lag. On decadal time scales, local and remote mechanisms act
contemporaneously in shaping the decadal biogeochemical response to the NAO. The slow
circulation adjustment, in response to NAO wind stress curl anomalies, causes a basin
redistribution of heat, freshwater, and biogeochemical properties which, in turn, modifies the spatial structure of the subpolar chlorophyll bloom.
Description:
Published
Description:
C07023
Description:
3.7. Dinamica del clima e dell'oceano
Description:
JCR Journal
Description:
restricted
Keywords:
PELAGOS
;
Earth System Model
;
03. Hydrosphere::03.01. General::03.01.03. Global climate models
;
03. Hydrosphere::03.03. Physical::03.03.03. Interannual-to-decadal ocean variability
;
03. Hydrosphere::03.03. Physical::03.03.04. Upper ocean and mixed layer processes
;
03. Hydrosphere::03.04. Chemical and biological::03.04.01. Biogeochemical cycles
;
03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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