Rapid reconstruction of paleoenvironmental features using a new multiplatform program (original) (raw)
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Paleoceanography and Paleoclimatology, 2019
The ongoing anthropogenic-induced warming assessment requires a robust background from regional sea surface temperature (SST) reconstructions. Planktonic foraminifera have yielded valuable insights into late Quaternary SST dynamics, but the techniques to estimate SST from fossil assemblages have only rarely been used in very recent sedimentary records (the last 2,000 years). Here we use two transfer function methods, modern analog technique and artificial neural networks, to reconstruct SST variability in two cores from the Central Mediterranean Sea that span the last five centuries. Both cores show similar and considerable changes in the planktonic foraminifera assemblages. However, the inferred mean annual SSTs only varied in a narrow range, in agreement with instrumental data that go back to 1850 CE. Our reconstructions extend this time frame and indicate that SST variability did not exceed 1.5°C over the past three centuries. Rather than temperature, we suggest that the changes in the assemblages reflect switches between sea surface winter/spring productivity and a deep winter mixed layer, due to the atmosphere/ocean interplay that governs different productivity modes in neighboring mesoscale gyres.
Glacial Mediterranean sea surface temperatures based on planktonic foraminiferal assemblages
Quaternary Science Reviews, 2005
We present a new reconstruction of Mediterranean sea surface temperatures (SST) during the last glacial maximum (LGM). A calibration data set based on census counts of 23 species of planktonic foraminifera in 129 North Atlantic and 145 Mediterranean core top samples was used to develop summer, winter and annual average SST reconstructions using artificial neural networks (ANNs) and the revised
Improving past sea surface temperature estimates based on planktonic fossil faunas
Paleoceanography, 1998
A new method of past sea surface temperature (SST) reconstruction based on the modem analog technique (Prell, 1985) and on the indirect approach (Bartlein et al., 1986) has been developed: the revised analog method (RAM). Applied to planktonic foraminifera, this technique leads to significant improvements in modem SST reconstruction with respect to former methods: our estimates are characterized by much lower residuals and a better coverage of the observed SST range. Moreover, the error of RAM estimates of past SSTs is lower than that associated with former reconstructions, particularly at middle and high latitudes. In low latitudes, cold season SSTs reconstructed by RAM during glacials are 1 ø-3øC lower than previously estimated. Our results tend thus to reconcile paleoestimates of glacial temperatures based on planktonic microfossils and on continental data in the tropics. '
Paleoceanography, 1996
We present a data set of 738 planktonic foraminiferal species counts from sediment surface samples of the eastern North Atlantic and the South Atlantic between 87øN and 40øS, 35øE and 60øW including published Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) data. These species counts are linked to Levitus's [1982] modern water temperature data for the four caloric seasons, four depth ranges (0, 30, 50, and 75 m), and the combined means of those depth ranges. The relation between planktonic foraminiferal assemblages and sea surface temperature (SST) data is estimated using the newly developed SIMMAX technique, which is an acronym for a modern analog technique (MAT) with a similarity index, based on (1) the scalar product of the normalized faunal percentages and (2) a weighting procedure of the modern analog's SSTs according to the inverse geographical distances of the most similar samples. Compared to the classical CLIMAP transfer technique and conventional MAT techniques, SIMMAX provides a more confident reconstruction of paleo-SSTs (correlation coefficient is 0.994 for the caloric winter and 0.993 for caloric summer). The standard deviation of the residuals is 0.90øC for caloric winter and 0.96øC for caloric summer at 0-m water depth. The SST estimates reach optimum stability (standard deviation of the residuals is 0.88øC) at the average 0-to 75-m water depth. Our extensive database provides SST estimates over a range of-1.4 to 27.2øC for caloric winter and 0.4 to 28.6øC for caloric summer, allowing SST estimates which are especially valuable for the high-latitude Atlantic during glacial times. Heinze and Maier-Reimer, 1991; Maier-Reimer and Mikolajewicz, 1991 ] requires an equivalent advancement in the precision and reliability of paleoclimatic proxy data to test the models [cf. Ravelo et al., 1990]. One of the most important paleoclimate data sets used in climate models is sea surface temperature (SST). The transfer technique to derive SSTs, based on quantitative counts of microfaunal components, has been established worldwide [Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP), 1981, 1984; Guiot, 1991].
Open Geosciences, 2017
Paleoclimatic data are essential for fingerprinting the climate of the earth before the advent of modern recording instruments. They enable us to recognize past climatic events and predict future trends. Within this framework, a conceptual and logical model was drawn to physically implement a paleoclimatic database named WDB-Paleo that includes the paleoclimatic proxies data of marine sediment cores of the Mediterranean Basin. Twenty entities were defined to record four main categories of data: a) the features of oceanographic cruises and cores (metadata); b) the presence/absence of paleoclimatic proxies pulled from about 200 scientific papers; c) the quantitative analysis of planktonic and benthonic foraminifera, pollen, calcareous nannoplankton, magnetic susceptibility, stable isotopes, radionuclides values of about 14 cores recovered by Institute for Coastal Marine Environment (IAMC) of Italian National Research Council (CNR) in the framework of several past research projects; d)...
1] Seasonal changes in surface ocean temperature are increasingly recognized as an important parameter of the climate system. Here we assess the potential of analyzing single-specimen planktonic foraminifera as proxy for the seasonal temperature contrast (seasonality). Oxygen isotopes and Mg/Ca ratios were measured on single specimens of Globigerinoides ruber, extracted from surface sediment samples of the Mediterranean Sea and the adjacent Atlantic Ocean. Variability in d 18 O and Mg/Ca was then compared to established modern seasonal changes in temperature and salinity for both regions. The results show that (1) average d 18 O-derived temperatures correlate with modern annual average temperatures for most sites, (2) the range in d 18 O-and Mg/Ca-derived temperature estimates from single-specimen analysis resembles the range in seasonal temperature values at the sea surface (0-50 m) in the Mediterranean Sea and the Atlantic Ocean, and there is no strong correlation between Mg/Ca-and d 18 O-derived temperatures from the same specimens in the current data set, indicating that other parameters (salinity, carbonate ion concentration, symbiont activity, ontogenesis, and natural variability) potentially affect these proxies. Citation: Wit, J. C., G.-J. Reichart, S. J. A Jung, and D. Kroon (2010), Approaches to unravel seasonality in sea surface temperatures using paired single-specimen foraminiferal d 18 O and Mg/Ca analyses, Paleoceanography, 25, PA4220,
Marine sea surface paleotemperatures
2004
Ma ap ps s -e ex xp pl la an na at to or ry y n no ot te es s 1 M Ma ar ri in ne e S Se ea a S Su ur rf fa ac ce e P Pa al la ae eo ot te em mp pe er ra at tu ur re e