Relict inland mangrove ecosystem reveals Last Interglacial ...
Intensification Changes of the Interglacial Subpolar Gyre System in the North Atlantic Region
1
AN OPTIMISTIC VIEW ON PROXY DATA INTEGRATION AND ASSIMILATION – WHY DID WE DUMP THE ERRORS? Christian Kamenik. Bern University/Oeschger Centre for Climate Change, Switzerland E-mail address: [email protected] Proxy data integration and the assimilation of past environmental changes (PDIA) are repeatedly discouraged by mismatches among individual reconstructions. These reconstructions often stem from natural, non- annual archives dated with radionuclides that provide probabilistic age- depth relationships with complex error structures. These errors are usually neglected during PDIA because their propagation into time-dependent rates, into models for calibration-in-time and finally into reconstructions is difficult to assess. Here, we do not restrict ourselves to 'best guess' single time series of environmental change. Instead, we produce 'swarms' of reconstructions that provide realistic estimates of even complex error structures along time and the environmental variable of interest simul- taneously. We permute through a large number of potential age-depth relationships of the archive of interest. For each individual permutation we develop calibration models along time and reconstruct the environmental variable of interest. Using PDIA, we score each individual permutation against other independent reconstructions. In combination with PDIA our 'swarms' of reconstructions thus lead to an integrated instead of a 'best guess' scenario of past environmental change. THE NEW LAKES: GLACIER LAKE OUTBURSTS AT THE GRUBEN GLACIER (BERNESE ALPS, SWITZERLAND) AND THEIR GEOLOGICAL IMPACTS Corinne Kämpfer. University of Bern, Switzerland E-mail address: [email protected] At the beginning of the 20th century, a glacial lake formed on the side of the Gruben glacier nearby the Grimsel Pass in the eastern Bernese Alps. Melt water of a melting tributary glacier was impounded by an almost 30 m high wall of ice. That lake went largely unnoticed until its outburst on October 4th 1921. A debris flow triggered by the outburst devastated the Aerlenalp, an alpine pasture about 3 km below the lake, as well as the alp cabin located on the pasture. Further down, in the main valley, the road leading to the Grimsel Pass got damaged. The flood reached as far as 15 km downstream to Innertkirchen. Between 1923 and 1928 the lake, now monitored closely, drained and refilled repeatedly without causing another debris flow. A sudden drainage in 1942 had similar consequences as in 1921. Ever since, the lake has been drained artificially to regulate the accumulating melt water. Today, traces of the glacier lake outburst are still visible. Lake sediments, an eroded riverbed, and the alluvial fan on the Aerlenalp are evidence of those debris flows. Those traces are mapped onsite so as to create a glacio-geomorphological map which documents the geological effects of glacier lake outbursts. Additional information is gained from aerial photographs, digital elevation models, and historical documents and serves to better understand the processes before, during and after the outbursts. Additionally, different lake and glacier sediments are analyzed in the laboratory. Furthermore, the changes of and around the Gruben glacier are to be documented. The location of the Gruben glacier makes it possible to study the geological impacts of a glacier lake outburst, its erosive forms and depositions. Also, the Gruben glacier lake represents a good example of how human interventions can lead to an effective handling of natural hazards – ranging from the construction of a gallery to control the water level to the use for hydropower today. INTENSIFICATION CHANGES OF THE INTERGLACIAL SUBPOLAR GYRE SYSTEM IN THE NORTH ATLANTIC REGION Evgeniya Kandiano. IFM-GEOMAR, Leibniz Institute of Marine Sciences, Germany E-mail address: [email protected] We present a detailed reconstruction of the meridional sea surface temperature (SST) pattern across various peak interglacials (Holocene, MIS 5e, MIS11) using marine sites from the upwelling area off NW Africa, the western Mediterranean Sea, the subpolar NE Atlantic and the Nordic Seas. Sea surface temperatures (SST) were reconstructed using foraminiferal assemblages and alkenones, further supported by planktic and benthic O- isotope records as well as some sedimentological proxis. In addition, and to refine our paleoceanographic interpretative basis, also alternative fora- miniferal counts of rare species and from the smaller size fractions (80mm) were employed. Both sets of SST demonstrate a seesaw pattern between the mid-Atlantic latitudes and the North. For instance, warm conditions in the North during the Holocene were associated with 1-2 C cold anomalies in the lower latitudes. On the contrary, during MIS 11 and MIS 5e relatively cold conditions in the North were coincident with enhanced SSTs in the southern regions. We relate these latitudinal SST differences to intensity changes of the warm water advection into these regions. It is therefore further hypothesize that under a pronounced interglacial climate regime the suppression of the meridional warm water flow into the North might result from a specific atmospheric circulation characterized by enhanced W-E zonality within the mid-latitudes, causing a strengthening of the subpolar gyre, thereby bringing about a prevalence of enhanced temper- atures and moisture. MINERAL DUST CHEMISTRY, MINERALOGY, SHAPE, MIXING STATE, COMPLEX REFRACTIVE INDEX AND MICROPHYSICS DETERMINED BY ELECTRON/OPTICAL MICROSCOPY AND BY X-RAY DIFFRACTION AT PRAIA, CAPE VERDE, IN WINTER 2008 Konrad Kandler. Umweltmineralogie, Technische Universität Darmstad, Germany E-mail address: [email protected] A large field experiment of the Saharan Mineral Dust Experiment (SAMUM) was performed in Praia, Cape Verde, in January and February 2008. Three dust periods were recorded during the measurements, divided by transitional periods and embedded in maritime-influenced situations. Approximately 48,000 individual particles were analyzed by automated scanning electron microscopy. The aerosol at Praia is a super- position of mineral dust, sea-salt, sulfates, and soot. Particles smaller than 500nm are mainly mineral dust, mineral dust-sulfate-mixtures, sulfates, and soot-sulfate-mixtures. Particles larger then 2.5mm consist of mineral dust, sea-salt, and few mineral dust-sulfate-mixtures. A transition range exists in between. The major internal mixtures are mineral dust-sulfate and soot-sulfate. Mineral dust-sea-salt mixtures occur occasionally, mineral dust-soot mixtures were not observed. The aspect ratio was 1.3-1.4 for dry particles smaller than 500nm and 1.6-1.7 for larger ones. While the real part of the refractive index showed low variation (1.55-1.58 at 532nm), a multi-modal imaginary part was detected as function of particle size, reflecting the complex composition. Soot mainly influences the absorption for wavelengths longer than the hematite absorption edge, while for shorter wavelengths dust is dominating. The refractive index of the aerosol is depending on the source region of the mineral dust and on the presence/ absence of a marine component. Four modes were identified in the size distribution. The first mode (50-70nm) and partly the second (700- 1100nm) can be regarded as of marine origin, but some dust contributes to the latter. The third mode (2-4mm) is dominated by advected dust, while the intermittently occurring fourth mode (15-70mm) may have a local contribution. By X-ray diffraction it was determined that the total sus- pended dust (bulk) consisted of kaolinite, K-feldspar, quartz, plagioclase, illite, gypsum, halite, and calcite. REGIONAL CHANGES IN ESTONIAN VEGETATION DURING THE HOLOCENE BASED ON THE REVEALS RECONSTRUCTION APPROACH Mihkel Kangur. Institute of Ecology at Tallinn University, Estonia E-mail address: [email protected] Modern regional flora and vegetation in Estonia reflect the north-south gradient of the major soil types influenced by the Ordovician limestone to the north and Devonian sandstone to the south. Accordingly, the regional dynamics and spatial structure of vegetation in the Holocene are assumed to differ along the gradient, even though climate variability and other factors would also have influenced. We evaluate the extent to which the soil gradient and the regional vegetation development correlate by using fossil pollen records from seventeen lakes where at least three radiocarbon Abstracts / Quaternary International 279-280 (2012) 233–345 234
Transcript of Intensification Changes of the Interglacial Subpolar Gyre System in the North Atlantic Region
Abstracts / Quaternary International 279-280 (2012) 233–345234
AN OPTIMISTIC VIEW ON PROXY DATA INTEGRATION ANDASSIMILATION – WHY DID WE DUMP THE ERRORS?
Christian Kamenik. Bern University/Oeschger Centre for Climate Change,SwitzerlandE-mail address: [email protected]
Proxy data integration and the assimilation of past environmental changes(PDIA) are repeatedly discouraged by mismatches among individualreconstructions. These reconstructions often stem from natural, non-annual archives dated with radionuclides that provide probabilistic age-depth relationships with complex error structures. These errors are usuallyneglected during PDIA because their propagation into time-dependentrates, intomodels for calibration-in-time and finally into reconstructions isdifficult to assess. Here, we do not restrict ourselves to 'best guess' singletime series of environmental change. Instead, we produce 'swarms' ofreconstructions that provide realistic estimates of even complex errorstructures along time and the environmental variable of interest simul-taneously. We permute through a large number of potential age-depthrelationships of the archive of interest. For each individual permutationwedevelop calibration models along time and reconstruct the environmentalvariable of interest. Using PDIA, we score each individual permutationagainst other independent reconstructions. In combination with PDIA our'swarms' of reconstructions thus lead to an integrated instead of a 'bestguess' scenario of past environmental change.
THE NEW LAKES: GLACIER LAKE OUTBURSTS AT THE GRUBEN GLACIER(BERNESE ALPS, SWITZERLAND) AND THEIR GEOLOGICAL IMPACTS
Corinne Kämpfer. University of Bern, SwitzerlandE-mail address: [email protected]
At the beginning of the 20th century, a glacial lake formed on the side ofthe Gruben glacier nearby the Grimsel Pass in the eastern Bernese Alps.Melt water of a melting tributary glacier was impounded by an almost 30m high wall of ice. That lake went largely unnoticed until its outburst onOctober 4th 1921. A debris flow triggered by the outburst devastated theAerlenalp, an alpine pasture about 3 km below the lake, as well as the alpcabin located on the pasture. Further down, in the main valley, the roadleading to the Grimsel Pass got damaged. The flood reached as far as 15 kmdownstream to Innertkirchen. Between 1923 and 1928 the lake, nowmonitored closely, drained and refilled repeatedly without causinganother debris flow. A sudden drainage in 1942 had similar consequencesas in 1921. Ever since, the lake has been drained artificially to regulate theaccumulating melt water. Today, traces of the glacier lake outburst are stillvisible. Lake sediments, an eroded riverbed, and the alluvial fan on theAerlenalp are evidence of those debris flows. Those traces are mappedonsite so as to create a glacio-geomorphological map which documentsthe geological effects of glacier lake outbursts. Additional information isgained from aerial photographs, digital elevation models, and historicaldocuments and serves to better understand the processes before, duringand after the outbursts. Additionally, different lake and glacier sedimentsare analyzed in the laboratory. Furthermore, the changes of and around theGruben glacier are to be documented. The location of the Gruben glaciermakes it possible to study the geological impacts of a glacier lake outburst,its erosive forms and depositions. Also, the Gruben glacier lake representsa good example of how human interventions can lead to an effectivehandling of natural hazards – ranging from the construction of a gallery tocontrol the water level to the use for hydropower today.
INTENSIFICATION CHANGES OF THE INTERGLACIAL SUBPOLAR GYRESYSTEM IN THE NORTH ATLANTIC REGION
Evgeniya Kandiano. IFM-GEOMAR, Leibniz Institute of Marine Sciences,GermanyE-mail address: [email protected]
We present a detailed reconstruction of the meridional sea surfacetemperature (SST) pattern across various peak interglacials (Holocene, MIS5e, MIS11) using marine sites from the upwelling area off NW Africa, thewestern Mediterranean Sea, the subpolar NE Atlantic and the Nordic Seas.
Sea surface temperatures (SST) were reconstructed using foraminiferalassemblages and alkenones, further supported by planktic and benthic O-isotope records as well as some sedimentological proxis. In addition, and torefine our paleoceanographic interpretative basis, also alternative fora-miniferal counts of rare species and from the smaller size fractions (80mm)were employed. Both sets of SST demonstrate a seesaw pattern betweenthe mid-Atlantic latitudes and the North. For instance, warm conditions inthe North during the Holocene were associated with 1-2�C cold anomaliesin the lower latitudes. On the contrary, during MIS 11 and MIS 5e relativelycold conditions in the North were coincident with enhanced SSTs in thesouthern regions. We relate these latitudinal SST differences to intensitychanges of the warm water advection into these regions. It is thereforefurther hypothesize that under a pronounced interglacial climate regimethe suppression of the meridional warm water flow into the North mightresult from a specific atmospheric circulation characterized by enhancedW-E zonality within the mid-latitudes, causing a strengthening of thesubpolar gyre, thereby bringing about a prevalence of enhanced temper-atures and moisture.
MINERAL DUST CHEMISTRY, MINERALOGY, SHAPE, MIXING STATE,COMPLEX REFRACTIVE INDEX AND MICROPHYSICS DETERMINED BYELECTRON/OPTICAL MICROSCOPY AND BY X-RAY DIFFRACTION ATPRAIA, CAPE VERDE, IN WINTER 2008
Konrad Kandler. Umweltmineralogie, Technische Universität Darmstad,GermanyE-mail address: [email protected]
A large field experiment of the Saharan Mineral Dust Experiment(SAMUM) was performed in Praia, Cape Verde, in January and February2008. Three dust periods were recorded during the measurements,divided by transitional periods and embedded in maritime-influencedsituations. Approximately 48,000 individual particles were analyzed byautomated scanning electron microscopy. The aerosol at Praia is a super-position of mineral dust, sea-salt, sulfates, and soot. Particles smaller than500nm are mainly mineral dust, mineral dust-sulfate-mixtures, sulfates,and soot-sulfate-mixtures. Particles larger then 2.5mm consist of mineraldust, sea-salt, and few mineral dust-sulfate-mixtures. A transition rangeexists in between. The major internal mixtures are mineral dust-sulfateand soot-sulfate. Mineral dust-sea-salt mixtures occur occasionally,mineral dust-sootmixtures were not observed. The aspect ratiowas 1.3-1.4for dry particles smaller than 500nm and 1.6-1.7 for larger ones. While thereal part of the refractive index showed low variation (1.55-1.58 at 532nm),a multi-modal imaginary part was detected as function of particle size,reflecting the complex composition. Soot mainly influences the absorptionfor wavelengths longer than the hematite absorption edge, while forshorter wavelengths dust is dominating. The refractive index of the aerosolis depending on the source region of the mineral dust and on the presence/absence of a marine component. Four modes were identified in the sizedistribution. The first mode (50-70nm) and partly the second (700-1100nm) can be regarded as of marine origin, but some dust contributes tothe latter. The third mode (2-4mm) is dominated by advected dust, whilethe intermittently occurring fourth mode (15-70mm) may have a localcontribution. By X-ray diffraction it was determined that the total sus-pended dust (bulk) consisted of kaolinite, K-feldspar, quartz, plagioclase,illite, gypsum, halite, and calcite.
REGIONAL CHANGES IN ESTONIAN VEGETATION DURING THEHOLOCENE BASED ON THE REVEALS RECONSTRUCTION APPROACH
Mihkel Kangur. Institute of Ecology at Tallinn University, EstoniaE-mail address: [email protected]
Modern regional flora and vegetation in Estonia reflect the north-southgradient of the major soil types influenced by the Ordovician limestone tothe north and Devonian sandstone to the south. Accordingly, the regionaldynamics and spatial structure of vegetation in the Holocene are assumedto differ along the gradient, even though climate variability and otherfactors would also have influenced. We evaluate the extent to which thesoil gradient and the regional vegetation development correlate by usingfossil pollen records from seventeen lakes where at least three radiocarbon
