Michael Schulz

University of Bremen

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Co-Authors

Matthias Prange

University of Bremen

121

André Paul

University of Bremen

Stefan Mulitza

University of Bremen

Michal Kučera

University of Bremen

Ute Merkel

University of Bremen

Vidya Varma

National Institute of Water and Atmospheric Research

Enno Schefuß

University of Bremen

David Heslop

Australian National University

Michael Sarnthein

Kiel University

Rima Rachmayani

Bandung Institute of Technology

Cooperative Institutions

University of Bremen

124

Centre National de la Recherche Scientifique

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Kiel University

GEOMAR Helmholtz Centre for Ocean Research Kiel

Laboratoire des Sciences du Climat et de l'Environnement

Universität Hamburg

University of Bern

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

Max Planck Institute for Meteorology

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Holocene Climate Variability on Centennial-to-Millennial Time Scales: 1. Climate Records from the North-Atlantic Realm

Springer eBooks (2002)

Michael Schulz André Paul

Ice core

Climate state

Paleoclimatology

Climate system

Temperature record

Abrupt climate change

10.1007/978-3-662-04965-5_4

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Citations (114)

Holocene evolution of the Southern Hemisphere westerly winds in transient simulations with global climate models

Climate of the past (2012)

Vidya Varma Matthias Prange Ute Merkel Thomas Kleinen Gerrit Lohmann

Abstract. The Southern Hemisphere Westerly Winds (SWW) have been suggested to exert a critical influence on global climate through the wind-driven upwelling of deep water in the Southern Ocean and the potentially resulting atmospheric CO2 variations. The investigation of the temporal and spatial evolution of the SWW along with forcings and feedbacks remains a significant challenge in climate research. In this study, the evolution of the SWW under orbital forcing from the mid-Holocene (7 kyr BP) to pre-industrial modern times (250 yr BP) is examined with transient experiments using the comprehensive coupled global climate model CCSM3. In addition, a model inter-comparison is carried out using orbitally forced Holocene transient simulations from four other coupled global climate models. Analyses and comparison of the model results suggest that the annual and seasonal mean SWW were subject to an overall strengthening and poleward shifting trend during the course of the mid-to-late Holocene under the influence of orbital forcing, except for the austral spring season, where the SWW exhibited an opposite trend of shifting towards the equator.

Westerlies

Forcing (mathematics)

Orbital forcing

Climate state

10.5194/cp-8-391-2012

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Citations (71)

Influence of topography on tropical African vegetation coverage

Climate Dynamics (2015)

Gerlinde Jung Matthias Prange Michael Schulz

Tropical rain forest

Tropical Asia

10.1007/s00382-015-2716-9

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Citations (14)

A forward and inverse transformation program for the “Atlas of Lithological-Paleogeographical Maps of the World”

Computers & Geosciences (1995)

Michael Schulz Christopher N. Wold A. B. Ronov William W. Hay

Map projection

ASCII

Longitude

Geographic coordinate system

10.1016/0098-3004(95)00024-3

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Citations (3)

A particle filter method to estimate the state of the ocean during the Last Glacial Maximum

EGU General Assembly Conference Abstracts (2018)

Charlotte Breitkreuz André Paul Peter Jan van Leeuwen Michael Schulz

Particle (ecology)

Source

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Citations (0)

Raw data and interpolated raw data from proxy records of sediment core GeoB6007-1

Audrey Morley Michael Schulz Yair Rosenthal Stefan Mulitza André Paul

Sediment core

Proxy (statistics)

10.1594/pangaea.770708

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Citations (0)

Major element data for tropical western Africa for samples from the Last Glacial Maximum, Heinrich Stadial 1, the mid-Holocene and the late Holocene

James A Collins Enno Schefuß David Heslop Stefan Mulitza Matthias Prange

Stadial

10.1594/pangaea.757398

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Modelling the ocean circulation of the mid-Cretaceous using the Community Earth System Model (iCESM1.2) and the internal wave mixing parameterization IDEMIX

Siva Kattamuri André Paul Friederike Pollmann Michael Schulz

The mid-Cretaceous (~90 Ma) was a natural case of the greenhouse climate state of the earth. Enhanced volcanic activity contributed to the higher atmospheric concentration of CO2. The continental configuration was different and the global mean sea level was around 160m higher compared to the present day.  Black shales from this period's marine sediments indicate a near-anoxic deep-ocean environment. This project hypothesizes that redistribution of tidal energy dissipation from the open ocean to the large continental shelf areas reduced the energy available for mixing in the deep ocean. The objective is to investigate the effect of climate parameters and geographical configuration on ocean circulation by using the energetically consistent internal wave mixing parameterization IDEMIX in the fully coupled Earth System Model iCESM1.2. As part of the second phase of the CRC - Transregio 181, this project aims to make the Earth system model energetically consistent for improved climate projections.The paleo-topography/bathymetry of the mid-Cretaceous is adopted from Scotese and Wright’s PALEOMAP (2018) project. The paleo-vegetation distribution is taken from Sewall’s (2007) mid-Cretaceous boundary conditions. The necessary boundary conditions and the climate-forcing files for the individual component models are prepared by using the Paleoclimate ToolKit of the CESM documentation. This mid-Cretaceous setup is spun-up with present-day trace gas concentrations for over 1000 model years. Constant tidal mixing coefficients are used in this spin-up. The first results from this spin-up indicate deep-water formation in the mid-latitudes in the Northern Hemisphere. From the equilibrium state of the spin-up, trace gas concentrations of the mid-Cretaceous will be input in the model. The ocean circulation will then be simulated with the internal wave mixing schemes KPP and IDEMIX for a comparative study. We expect improved results for deep-water formation sites and deep-ocean oxygenation with the IDEMIX parameterization.

Paleoclimatology

10.5194/egusphere-egu23-7686

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Citations (0)

Abrupt cold events in the North Atlantic Ocean in a transient Holocene simulation

Climate of the past (2018)

Andrea Klus Matthias Prange Vidya Varma Louis Bruno Tremblay Michael Schulz

Abstract. Abrupt cold events have been detected in numerous North Atlantic climate records from the Holocene. Several mechanisms have been discussed as possible triggers for these climate shifts persisting decades to centuries. Here, we describe two abrupt cold events that occurred during an orbitally forced transient Holocene simulation using the Community Climate System Model version 3. Both events occurred during the late Holocene (4305–4267 BP and 3046–3018 BP for event 1 and event 2, respectively). They were characterized by substantial surface cooling (−2.3 and −1.8 ∘C, respectively) and freshening (−0.6 and −0.5 PSU, respectively) as well as severe sea ice advance east of Newfoundland and south of Greenland, reaching as far as the Iceland Basin in the northeastern Atlantic at the climaxes of the cold events. Convection and deep-water formation in the northwestern Atlantic collapsed during the events, while the Atlantic Meridional Overturning Circulation was not substantially affected (weakening by only about 10 % and 5 %, respectively). The events were triggered by prolonged phases of a positive North Atlantic Oscillation that caused substantial changes in the subpolar ocean circulation and associated freshwater transports, resulting in a weakening of the subpolar gyre. Our results suggest a possible mechanism by which abrupt cold events in the North Atlantic region may be triggered by internal climate variability without the need of an external (e.g., solar or volcanic) forcing.

Holocene climatic optimum

Forcing (mathematics)

10.5194/cp-14-1165-2018

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Citations (22)

Synchronous and proportional deglacial changes in Atlantic meridional overturning and northeast Brazilian precipitation

Paleoceanography (2017)

Stefan Mulitza Cristiano Mazur Chiessi Enno Schefuß Jörg Lippold David Wichmann

Abstract Changes in heat transport associated with fluctuations in the strength of the Atlantic meridional overturning circulation (AMOC) are widely considered to affect the position of the Intertropical Convergence Zone (ITCZ), but the temporal immediacy of this teleconnection has to date not been resolved. Based on a high‐resolution marine sediment sequence over the last deglaciation, we provide evidence for a synchronous and near‐linear link between changes in the Atlantic interhemispheric sea surface temperature difference and continental precipitation over northeast Brazil. The tight coupling between AMOC strength, sea surface temperature difference, and precipitation changes over northeast Brazil unambiguously points to a rapid and proportional adjustment of the ITCZ location to past changes in the Atlantic meridional heat transport.

Intertropical Convergence Zone

Deglaciation

Teleconnection

Tropical Atlantic

10.1002/2017pa003084

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Citations (133)