Identification

Title

Mechanisms regulating coccolithophore dynamics in the Great Calcite Belt in the Southern Ocean in the Community Earth System Mode

Abstract

The Great Calcite Belt (GCB) is a region of elevated particulate inorganic carbon (PIC) generated by coccolithophore growth that spans the subantarctic Southern Ocean. The GCB is thought to play an important role in the global carbon cycle. Coccolithophores, however, are sensitive to multiple climate-related environmental factors. To understand these controls on Southern Ocean coccolithophores comprising the GCB, we explore its major bottom-up and top-down processes using the Community Earth System Model (CESM). We find that coccolithophore biomass accumulates where both macronutrients and iron are available at concentrations greater than ∼50% of their half-saturation constants, and temperature is more limiting than both light and nutrients. Coccolithophore biomass is decoupled from growth rates due to top-down control. At higher temperatures and lower latitudes, microzooplankton grazing outpaces coccolithophore growth. This occurs because the temperature dependence of grazing is parameterized with an exponential (Q<sub style="bottom:-0.25em;box-sizing:border-box;font-size:12px;line-height:0;position:relative;vertical-align:baseline;">10</sub>) function, whereas coccolithophore growth is parameterized with a power function; these temperature curves diverge at higher temperatures. While the extent of the GCB is primarily controlled by temperature, its magnitude is most strongly controlled by environmental factors affecting iron concentrations. Our results suggest that (a) the temperature relationships for both coccolithophore growth and its loss terms are critical for resolving a GCB in CESM, and (b) the spatial extent of Southern Ocean coccolithophores may be sensitive to continued increases in sea surface temperatures.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.net/ark:/85065/d7sn0f97

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2024-11-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact