Brief description
The purpose of this study was to estimate past sea-surface temperature in the Southeast Indian Ocean. The accumulation of diatom microplankton assemblages in sediments being the proxy for these records of climatic change.A transfer function is a mathematical method that allows quantitative estimations of environmental parameters from past biogenic sedimentation. In this study, a diatom transfer function was established to relate biological species to selected environmental parameter of the ocean (sea-surface temp). These equations were then employed on observed fossil species from core samples to provide quantitative estimates of sea-surface temperature.
Estimates of sea-surface temperature (SST) are given here based on the assemblages of diatoms found in core MD88-787. The information provided gives the extrapolated age-scale through the core, and an estimate of August SST based on a diatom transfer function - DTF 109/24/6.
Lineage
Maintenance and Update Frequency: notPlanned
Statement: Three sources of data are procured to perform the Diatom Transfer Function (DTF). The first set taken is the ranked diatom species data from core tops (i.e. Antarctic Diatom Database). The second data set is taken from the modern environmental variable to be related. In this study, the present-day reference for sea-surface temperature, the World Ocean Atlas (WOA, 1994) is used. The third dataset comprises the down-core data which contains the ranked data derived from the same diatom species used in the modern database.
The transfer function, DTF 109/24/6, under-estimates in the 4-8oC range and over-estimates in the 0-4oC range, but in each case the residuals are confined to within ±2oC. The model does not take into account dissolution of the diatoms in the samples, but does increase the number of factors to account for the wider distributional patterns.
The DTF have been shown in the reference 109 database to be possibly over-estimated by up to 1.5oC. The answer may simply lie in the fact that the 109 database is too small and restrictive.
Parameters for Antarctic Diatom Database: Diatom species, Leanne K. Armand code, core code, core coordinates (degrees, decimal minutes), total number of specimens recorded in each core, % of old species, % of data used in 24 major species
Parameters for historical sea-surface temperature estimates: Core depth (cm), analyseries extrapolated age scale (ka) at 10cm intervals, DTF commonality and sea-surface temperature August (oC).
Parameters for the raw diatom counts: Core depth (cm), diatom species, diatom subtotal and silica subtotal.
The transfer function, DTF 109/24/6, under-estimates in the 4-8oC range and over-estimates in the 0-4oC range, but in each case the residuals are confined to within ±2oC. The model does not take into account dissolution of the diatoms in the samples, but does increase the number of factors to account for the wider distributional patterns.
The DTF have been shown in the reference 109 database to be possibly over-estimated by up to 1.5oC. The answer may simply lie in the fact that the 109 database is too small and restrictive.
Parameters for Antarctic Diatom Database: Diatom species, Leanne K. Armand code, core code, core coordinates (degrees, decimal minutes), total number of specimens recorded in each core, % of old species, % of data used in 24 major species
Parameters for historical sea-surface temperature estimates: Core depth (cm), analyseries extrapolated age scale (ka) at 10cm intervals, DTF commonality and sea-surface temperature August (oC).
Parameters for the raw diatom counts: Core depth (cm), diatom species, diatom subtotal and silica subtotal.
Statement: Use of Alfred-Wegner-Institut computer programs PalaeoToolBox and MacTransfer (Sieger, Nov 1996) which incorporates the Imbrie and Kipp (1971) subroutines (Cabfac, Regress and Thread) have been used in the work produced here. These programs modernise and simplify the original Factor Analysis Package for PC's (Schrader 1989).
Notes
CreditCentre des Faibles Radioactivities mixte CNRS CEA (France)
Credit
Institute of Antarctic and Southern Ocean Studies (IASOS)
Institute of Antarctic and Southern Ocean Studies (IASOS)
Credit
Institut Français pour la Recherche et Technologie Polaires (IFRTP)
Institut Français pour la Recherche et Technologie Polaires (IFRTP)
Credit
Terres Australes et Antarctiques Françaises (TAAF)
Terres Australes et Antarctiques Françaises (TAAF)
Credit
Australian Postgraduate Research Award (APRA)
Australian Postgraduate Research Award (APRA)
Purpose
To estimate past sea-surface temperature in the southeast Indian Ocean
To estimate past sea-surface temperature in the southeast Indian Ocean
Issued: 18 09 2007
Data time period: 1988 to 1988
text: westlimit=145; southlimit=-56.50; eastlimit=145.5; northlimit=-56.00
text: uplimit=3030.4; downlimit=3020
Subjects
BIOLOGICAL CLASSIFICATION |
Diatoms |
EARTH SCIENCE |
MICROALGAE |
OCEAN TEMPERATURE |
OCEANS |
PLANTS |
Sea Surface Temperature |
Transfer function |
biota |
core_depth |
diatom_transfer_function_communality |
diatom_transfer_function_sea_surface_temperature |
environment |
extrapolated_age_scale |
latitude |
longitude |
taxonomic_group_count |
taxonomic_name |
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Other Information
Antarctic Diatom Database (App 3-2.pdf)
Historical August sea-surface temperature estimates at location of core MD88-787 (App 6-10.pdf)
Raw diatom counts through core MD88-787 (App 6-6 787.pdf)
Identifiers
- global : 10802fd0-6716-11dc-88d6-00188b4c0af8
