Kategorie: Proben

@inproceedings{marwan2019,

title = {Recurrence based entropies},

author = {Norbert Marwan and Kai Hauke Kraemer and Karolin Wiesner and Sebastian F. M. Breitenbach and Jens Leonhardt},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/04/EGU2019-2817.pdf},

year  = {2019},

date = {2019-04-08},

booktitle = {Geophysical Research Abstracts},

volume = {21},

pages = {EGU2019-2817},

abstract = {Dynamical processes in Earth sciences are often considered to be of complex nature. The term complexity is often used for processes that are either unpredictable (e.g. nonlinear dynamics), consist of many different components, or exhibit regime transitions (e.g. tipping points). To measure complexity, the Shannon entropy is often used.

Here we present various entropy measures that have been defined on the base of the recurrence plot. Because of the different features that are used, these entropy measures represent different aspects of the analysed system and, thus, behave differently. In the past, this fact has lead to difficulties in interpreting and understanding those measures. We summarize the definitions, the motivation and interpretation of these entropy measures, compare their differences and discuss some of the pitfalls when using them.

Finally, we illustrate their potential in an application on palaeoclimate time series. Using entropy measures, changes and transitions in the climate dynamics in the past can be identified and interpreted.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{breitenbach2018,

title = {Tracing past shifts of the boundary between maritime and continental climate over Central Europe},

author = {Sebastian F. M. Breitenbach and Birgit Plessen and Sarah Waltgenbach and Rik Tjallingii and Jens Leonhardt and Klaus-Peter Jochum and Hanno Meyer and Norbert Marwan and Denis Scholz},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/04/EGU2018-9046.pdf},

year  = {2018},

date = {2018-04-01},

booktitle = {Geophysical Research Abstracts},

volume = {20},

pages = {EGU2018-9046},

abstract = { European climate is characterized by heterogeneous climate conditions, with distinct boundaries between zones that can be classified according to the Köppen classification (Peel et al. 2007), and detected using climate network techniques (Rheinwalt et al. 2016). These boundaries are not stationary, but shift geographically, depending on large scale atmospheric conditions. Central European climate is strongly influenced by intricately linked North Atlantic Oscillation and Siberian High (SH), which govern precipitation and temperature over Europe. Shifts of these climatic boundaries in response to global warming and circulation changes might lead to more frequent extreme weather patterns like heat waves, with significant repercussions for society (Cohen et al. 2014). Speleothem-based palaeoclimate reconstructions enable us to understand underlying forcing mechanisms and speed of climatic reorganizations. Here we present a first reconstruction of multi-centennial shifts of the boundary between western European maritime Cfb climate and continental Dfb climate through the last ca. 5,000 years using speleothems from Bleßberg Cave, Thuringia, Central Europe. Thanks to its location near the Cfb-Dfb climatic boundary, Bleßberg Cave is ideally suited to reconstruct past W-E shifts of this divide longitudinally crossing Central Europe. We compare a decadally resolved stalagmite δ18O record with data from Bunker Cave (Mischel et al. 2017), western Germany, and an NAO reconstruction from Greenland (Olsen et al. 2012). Over the last 5,000 years, the boundary between Cfb and Dfb climate shifted repeatedly. When the Cfb-Dfb border was east (west) of Bleßberg (Bunker) Cave maritime (continental) climate prevailed at both sites. Discrepancies between investigated proxy records are found when the boundary is located between the two caves. Comparison with the Greenland NAO record shows that a westerly shifted boundary is often associated with a strong SH and a negative NAO. An easterly shift, in contrast, is found to be linked with weak a SH and a positive NAO.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{breitenbach2016,

title = {A multi-proxy reconstruction of Holocene climate change from Blessberg Cave, Germany},

author = {Sebastian F. M. Breitenbach and Birgit Plessen and Sarah Wenz and Jens Leonhardt and Rik Tjallingii and Denis Scholz and Klaus-Peter Jochum and Norbert Marwan},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/05/Breitenbach_poster_EGU_2016.pdf},

year  = {2016},

date = {2016-04-01},

booktitle = {Geophysical Research Abstracts},

volume = {18},

pages = {EGU2016-14213},

abstract = {Although Holocene climate dynamics were relatively stable compared to glacial conditions, climatic changes had significant impact on ecosystems and human society on various timescales (Mayewski et al. 2004, Donges et al. 2015, Tan et al. 2015). Precious few high-resolution records on Holocene temperature and precipitation conditions in Central Europe are available (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012).

Here we present a speleothem-based reconstruction of past climate dynamics from Blessberg Cave, Thuringia, central Germany. Three calcitic stalagmites were recovered when the cave was discovered during tunneling operations in 2008. Samples BB-1, -2 and -3 were precisely dated by the 230Th/U-method, with errors between 10 and 160 years (2σ). The combined record covers large parts of the Holocene (10 – 0.4 ka BP). δ13C and δ18O were analysed at 100 μm resolution. To gain additional insights in infiltration conditions, Sr/Ca and S/Ca were measured on BB-1 and BB-3 using an Röntgenanalytik Eagle XXL μXRF scanner.

Differences to other central European records (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012) suggest complex interaction between multiple factors influencing speleothem δ18O in Blessberg Cave. Furthermore, no clear influence of the North Atlantic Oscillation on our proxies is found. However, a link across the N Atlantic realm is indicated by a centennial-scale correlation between Blessberg δ18O values and minerogenic input into lake SS1220 in Greenland over the last 5 ka (Olsen et al. 2012). In addition, recurrence analysis indicates an imprint of Atlantic Bond events on Blessberg δ18O values (Marwan et al. 2014), corroborating the suggested link with high northern latitudes. Larger runoff into the Greenland lake seems to be associated with lower δ18O, higher δ13C and S/Ca ratios, as well as lower Sr/Ca ratios in Blessberg Cave speleothems. This might be linked to lower local temperature and/or changes in precipitation seasonality. Opposing millennial scale trends with lowering S/Ca ratios and δ13C values but increasing Sr/Ca ratios calls for more than one controlling factor. Most likely, δ13C decreased through the Holocene due to afforestation, which in turn might have increased sulphate retention in the thickening soil cover (Frisia et al. 2005) and limited sulphur flux into the cave. Alternatively, marine sulfur flux could have diminished with winter wind intensities. However, additional data is required to clarify this hypothesis. A positive Sr/Ca trend through the Holocene might result from increasing prior calcite precipitation induced by a negative moisture balance in summer.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{breitenbach2016,

title = {A multi-proxy reconstruction of Holocene climate change from Blessberg Cave, Germany},

author = {Sebastian F. M. Breitenbach and Birgit Plessen and Sarah Wenz and Jens Leonhardt and Rik Tjallingii and Denis Scholz and Klaus-Peter Jochum and Norbert Marwan},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/05/Breitenbach_poster_EGU_2016.pdf},

year  = {2016},

date = {2016-04-01},

booktitle = {Geophysical Research Abstracts},

volume = {18},

pages = {EGU2016-14213},

abstract = {Although Holocene climate dynamics were relatively stable compared to glacial conditions, climatic changes had significant impact on ecosystems and human society on various timescales (Mayewski et al. 2004, Donges et al. 2015, Tan et al. 2015). Precious few high-resolution records on Holocene temperature and precipitation conditions in Central Europe are available (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012).

Here we present a speleothem-based reconstruction of past climate dynamics from Blessberg Cave, Thuringia, central Germany. Three calcitic stalagmites were recovered when the cave was discovered during tunneling operations in 2008. Samples BB-1, -2 and -3 were precisely dated by the 230Th/U-method, with errors between 10 and 160 years (2σ). The combined record covers large parts of the Holocene (10 – 0.4 ka BP). δ13C and δ18O were analysed at 100 μm resolution. To gain additional insights in infiltration conditions, Sr/Ca and S/Ca were measured on BB-1 and BB-3 using an Röntgenanalytik Eagle XXL μXRF scanner.

Differences to other central European records (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012) suggest complex interaction between multiple factors influencing speleothem δ18O in Blessberg Cave. Furthermore, no clear influence of the North Atlantic Oscillation on our proxies is found. However, a link across the N Atlantic realm is indicated by a centennial-scale correlation between Blessberg δ18O values and minerogenic input into lake SS1220 in Greenland over the last 5 ka (Olsen et al. 2012). In addition, recurrence analysis indicates an imprint of Atlantic Bond events on Blessberg δ18O values (Marwan et al. 2014), corroborating the suggested link with high northern latitudes. Larger runoff into the Greenland lake seems to be associated with lower δ18O, higher δ13C and S/Ca ratios, as well as lower Sr/Ca ratios in Blessberg Cave speleothems. This might be linked to lower local temperature and/or changes in precipitation seasonality. Opposing millennial scale trends with lowering S/Ca ratios and δ13C values but increasing Sr/Ca ratios calls for more than one controlling factor. Most likely, δ13C decreased through the Holocene due to afforestation, which in turn might have increased sulphate retention in the thickening soil cover (Frisia et al. 2005) and limited sulphur flux into the cave. Alternatively, marine sulfur flux could have diminished with winter wind intensities. However, additional data is required to clarify this hypothesis. A positive Sr/Ca trend through the Holocene might result from increasing prior calcite precipitation induced by a negative moisture balance in summer.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{marwan2019,

title = {Recurrence based entropies},

author = {Norbert Marwan and Kai Hauke Kraemer and Karolin Wiesner and Sebastian F. M. Breitenbach and Jens Leonhardt},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/04/EGU2019-2817.pdf},

year  = {2019},

date = {2019-04-08},

booktitle = {Geophysical Research Abstracts},

volume = {21},

pages = {EGU2019-2817},

abstract = {Dynamical processes in Earth sciences are often considered to be of complex nature. The term complexity is often used for processes that are either unpredictable (e.g. nonlinear dynamics), consist of many different components, or exhibit regime transitions (e.g. tipping points). To measure complexity, the Shannon entropy is often used.

Here we present various entropy measures that have been defined on the base of the recurrence plot. Because of the different features that are used, these entropy measures represent different aspects of the analysed system and, thus, behave differently. In the past, this fact has lead to difficulties in interpreting and understanding those measures. We summarize the definitions, the motivation and interpretation of these entropy measures, compare their differences and discuss some of the pitfalls when using them.

Finally, we illustrate their potential in an application on palaeoclimate time series. Using entropy measures, changes and transitions in the climate dynamics in the past can be identified and interpreted.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{breitenbach2018,

title = {Tracing past shifts of the boundary between maritime and continental climate over Central Europe},

author = {Sebastian F. M. Breitenbach and Birgit Plessen and Sarah Waltgenbach and Rik Tjallingii and Jens Leonhardt and Klaus-Peter Jochum and Hanno Meyer and Norbert Marwan and Denis Scholz},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/04/EGU2018-9046.pdf},

year  = {2018},

date = {2018-04-01},

booktitle = {Geophysical Research Abstracts},

volume = {20},

pages = {EGU2018-9046},

abstract = { European climate is characterized by heterogeneous climate conditions, with distinct boundaries between zones that can be classified according to the Köppen classification (Peel et al. 2007), and detected using climate network techniques (Rheinwalt et al. 2016). These boundaries are not stationary, but shift geographically, depending on large scale atmospheric conditions. Central European climate is strongly influenced by intricately linked North Atlantic Oscillation and Siberian High (SH), which govern precipitation and temperature over Europe. Shifts of these climatic boundaries in response to global warming and circulation changes might lead to more frequent extreme weather patterns like heat waves, with significant repercussions for society (Cohen et al. 2014). Speleothem-based palaeoclimate reconstructions enable us to understand underlying forcing mechanisms and speed of climatic reorganizations. Here we present a first reconstruction of multi-centennial shifts of the boundary between western European maritime Cfb climate and continental Dfb climate through the last ca. 5,000 years using speleothems from Bleßberg Cave, Thuringia, Central Europe. Thanks to its location near the Cfb-Dfb climatic boundary, Bleßberg Cave is ideally suited to reconstruct past W-E shifts of this divide longitudinally crossing Central Europe. We compare a decadally resolved stalagmite δ18O record with data from Bunker Cave (Mischel et al. 2017), western Germany, and an NAO reconstruction from Greenland (Olsen et al. 2012). Over the last 5,000 years, the boundary between Cfb and Dfb climate shifted repeatedly. When the Cfb-Dfb border was east (west) of Bleßberg (Bunker) Cave maritime (continental) climate prevailed at both sites. Discrepancies between investigated proxy records are found when the boundary is located between the two caves. Comparison with the Greenland NAO record shows that a westerly shifted boundary is often associated with a strong SH and a negative NAO. An easterly shift, in contrast, is found to be linked with weak a SH and a positive NAO.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{breitenbach2016,

title = {A multi-proxy reconstruction of Holocene climate change from Blessberg Cave, Germany},

author = {Sebastian F. M. Breitenbach and Birgit Plessen and Sarah Wenz and Jens Leonhardt and Rik Tjallingii and Denis Scholz and Klaus-Peter Jochum and Norbert Marwan},

url = {https://bbh.pik-potsdam.de/wp-content/uploads/2021/05/Breitenbach_poster_EGU_2016.pdf},

year  = {2016},

date = {2016-04-01},

booktitle = {Geophysical Research Abstracts},

volume = {18},

pages = {EGU2016-14213},

abstract = {Although Holocene climate dynamics were relatively stable compared to glacial conditions, climatic changes had significant impact on ecosystems and human society on various timescales (Mayewski et al. 2004, Donges et al. 2015, Tan et al. 2015). Precious few high-resolution records on Holocene temperature and precipitation conditions in Central Europe are available (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012).

Here we present a speleothem-based reconstruction of past climate dynamics from Blessberg Cave, Thuringia, central Germany. Three calcitic stalagmites were recovered when the cave was discovered during tunneling operations in 2008. Samples BB-1, -2 and -3 were precisely dated by the 230Th/U-method, with errors between 10 and 160 years (2σ). The combined record covers large parts of the Holocene (10 – 0.4 ka BP). δ13C and δ18O were analysed at 100 μm resolution. To gain additional insights in infiltration conditions, Sr/Ca and S/Ca were measured on BB-1 and BB-3 using an Röntgenanalytik Eagle XXL μXRF scanner.

Differences to other central European records (e.g., von Grafenstein et al. 1999, Fohlmeister et al. 2012) suggest complex interaction between multiple factors influencing speleothem δ18O in Blessberg Cave. Furthermore, no clear influence of the North Atlantic Oscillation on our proxies is found. However, a link across the N Atlantic realm is indicated by a centennial-scale correlation between Blessberg δ18O values and minerogenic input into lake SS1220 in Greenland over the last 5 ka (Olsen et al. 2012). In addition, recurrence analysis indicates an imprint of Atlantic Bond events on Blessberg δ18O values (Marwan et al. 2014), corroborating the suggested link with high northern latitudes. Larger runoff into the Greenland lake seems to be associated with lower δ18O, higher δ13C and S/Ca ratios, as well as lower Sr/Ca ratios in Blessberg Cave speleothems. This might be linked to lower local temperature and/or changes in precipitation seasonality. Opposing millennial scale trends with lowering S/Ca ratios and δ13C values but increasing Sr/Ca ratios calls for more than one controlling factor. Most likely, δ13C decreased through the Holocene due to afforestation, which in turn might have increased sulphate retention in the thickening soil cover (Frisia et al. 2005) and limited sulphur flux into the cave. Alternatively, marine sulfur flux could have diminished with winter wind intensities. However, additional data is required to clarify this hypothesis. A positive Sr/Ca trend through the Holocene might result from increasing prior calcite precipitation induced by a negative moisture balance in summer.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}