Oct
26
Fri
2018
Ice2ice Bergen meeting @ U1 Big meeting room
Oct 26 @ 09:00 – 12:00

Emilie and Kerim – Heinrich events vs DO-stadials

Nov
1
Thu
2018
PI meeting @ CPH
Nov 1 – Nov 2 all-day
Nov
19
Mon
2018
Ice2ice Bergen meeting @ U1 Big meeting room
Nov 19 @ 09:00 – 12:00

Agenda will be announced later.

Nov
23
Fri
2018
PhD Defense by Diana Vladimirova
Nov 23 @ 13:00 – 17:00

Title: “High-resolution methane record of the RECAP ice core (Eastern Greenland) over the last climatic cycle”

Abstract: “Methane (CH4) is among the three most important greenhouse gases. Its concentration varied in the past and the only way to extract the information is to measure the past atmosphere samples trapped in the ice cores. We present the REnland ice CAP (RECAP) CH4 record covering the last glacial cycle (120 000 years).

The modern interglacial (Holocene) section (the last 11 700 years) represents the first continuous high-resolution methane record of the Northern Hemisphere and exhibits the centennial-scale variability. A possible explanation for this observation could be in the global teleconnection of the intertropical convergence zone and its influence on the monsoon activity, which in turn has an effect on the CH4 emissions for the tropical wetlands – the dominant source of methane.
During a part of the Last Glacial, we reveal that approximately 78 000 – 83 000 years ago an additional source of methane was active in the Northern Hemisphere. The environmental reconstructions suggest that it could be the boreal wetlands, exposed after the retreat of the ice sheet and the following drainage of ice-dammed lakes in the area.

As side projects, we also work on the improvement of the continuous flow analysis (CFA) technique for the gas applications – the technique used for the RECAP ice core measurements, and on the on-site CH4 measurements at the Eastern Greenland Ice core Project (EGRIP). We identify a diurnal variability of the CH4 concentration in the surface air an upper firn column, which was earlier considered as convectively mixed”.

Tid: 23. november 2018, kl. 13:00-17:00

Sted: Centre for Ice and Climate, Rockefeller Complex, Juliane Maries Vej 30, 2nd floor, room 235

Arrangør: Centre for Ice and Climate

Supervisor
Prof. Thomas Blunier, Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.

Assessment Committee
Ass. Prof. Anders Svensson, Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.
Ass. Prof. Giuliana Panieri, Centre for Arctic Gas Hydrate, Environment and Climate, UiT – The Arctic University of Norway.
Célia Sapart, Laboratoire de Glaciologie, Université Libre de Bruxelles.

Nov
26
Mon
2018
PhD defense Nicholas Rathmann
Nov 26 @ 13:00 – 17:00

Tid: 26. november 2018, kl. 13:00-17:00

Sted: Centre for Ice and Climate, rockefeller Complex, Juliane Maries Vej 30, 2nd floor, room 235

Arrangør: Centre for Ice and Climate

 

Abstract (long):
Nonlinear fluid motion occurs naturally in central components of the climate system. Studying such motion is instrumental for improving the accuracy and realism of models of climate components, which has important implications for future climate projections. This thesis presents four studies on the topic of nonlinear fluid dynamics addressing two subjects: the dynamics of ice sheet deformation and the dynamics of the turbulent energy cascade.
The first study investigates the controlling mechanisms of the observed 2016 seasonal speed-up of Zachariae and  Nioghalvfjerdsfjorden outlet glaciers in northeast Greenland, which drain a significant part of the Greenland ice sheet. From surface imagery made available by the newest generation of satellites, state-of-the-art velocity maps are derived, and the timings of processes potentially impacting the speed-up are estimated. By combining observations with numerical modelling, it is shown that the subglacial environment exerts an important control over the ice discharge rate of the region, which has implications for estimating the region’s contribution to near-term sea level rise.
The second study investigates the influence of strong single-maximum fabrics on the transient deformation of internal layers within ice sheets. By using a new Lagrangian numerical ice flow model, it is shown that discrete, strong single maximum layers — which may account for suppressed shearing along nonbasal crystallographic planes — are a plausible candidate for explaining the disturbed flow observed from ice-penetrating radar transects. The results have potential implications for interpreting ice-core stratigraphies and chronologies, as well as understanding of how internal disturbances might influence surrounding flow fields.
The third and fourth study address the origin of the transfer direction of kinetic energy between scales of motion  (upscale/downscale) in fully developed turbulence using the spectral-helical decomposition of the velocity field. In this decomposition, the nonlinear term in the Navier–Stokes equation becomes to a sum over eight distinct types of three-wave interactions. In the third study, a simple model (a shell model) is introduced to investigate the behaviour of the eight types of nonlinear interactions, which is compared to a linear stability analysis, finding a fair agreement.
In the fourth study, a subset of the three-wave interactions are shown to conserve a new positive-definite quadratic quantity in addition to kinetic energy, which cause the interactions to contribute to a reverse transfer of energy in three dimensions (small to large scales) in analogy to two-dimensional turbulence. Understanding the energy transfer directionality, and possible ties between two- and three-dimensional turbulence, has implications for geophysical flows such as the free atmosphere and oceans where vertical motion in many places is suppressed, thereby affecting predictability time scales and the transport of energy and momentum in climate.
Dec
4
Tue
2018
PI meeting @Bergen
Dec 4 – Dec 5 all-day
Ice2ice Bergen meeting @ U1 Big meeting room
Dec 4 @ 12:30 – 14:00

Camille Li and Andreas Born will present their newest paper “Coupled atmosphere-ice-ocean dynamics in Dansgaard-Oeschger events“ and we will have the opportunity to discuss with them. You can find the paper here; https://www.sciencedirect.com/science/article/pii/S0277379118305705

After the presentation and discussion, we will have a small Christmas event and serve you gløgg and something sweet to eat. Please indicate here if you want to join in, before Friday 30.11 at 12.

Abstract:
The Dansgaard-Oeschger events of the last ice age are among the best studied abrupt climate changes, yet a comprehensive explanation is still lacking. They are most pronounced in the North Atlantic, where they manifest as large temperature swings, on timescales of decades or shorter, between persistent cold (stadial) and warm (interstadial) conditions. This review examines evidence that Dansgaard-Oeschger events are an unforced or “spontaneous” oscillation of the coupled atmosphere-ice-ocean system comprising the North Atlantic, Nordic Seas and Arctic, collectively termed the Northern Seas. Insights from reanalysis data, climate model simulations, and idealized box model experiments point to the subpolar gyre as a key coupling region where vigorous wind systems encounter the southernmost extension of sea ice and the most variable currents of the North Atlantic, with connections to the deep ocean via convection. We argue that, under special conditions, these components can interact to produce Dansgaard- Oeschger events. Finding the sweet spot is a matter of understanding when the subpolar region enters a feedback loop whereby changes in wind forcing, sea ice cover, and ocean circulation amplify and sustain perturbations towards cold (ice-covered) or warm (ice-free) conditions. The resulting Dansgaard-Oeschger-like variability is seen in a handful of model simulations, including some “ugly duckling” pre-industrial simulations: these may be judged as undesirable at the outset, but ultimately show value in suggesting that current models include the necessary physics to produce abrupt climate transitions, but exhibit incorrect sensitivity to the boundary conditions. Still, glacial climates are hypothesized to favour larger, more persistent transitions due to differences in large-scale wind patterns. Simplified models and idealized experimental setups may provide a means to constrain how the critical processes act, both in isolation and in combination, to destabilize the subpolar North Atlantic.

Jan
14
Mon
2019
PI meeting @Bergen
Jan 14 – Jan 15 all-day
Jan
21
Mon
2019
Trial lecture – Henrik Sadatzki
Jan 21 @ 10:15 – 11:30

Title:

Low-latitude climate variability during the late Quaternary and teleconnections to high latitudes

 

Time:        Mandag 21. januar 2019, kl. 10.15

Venue:     Auditorium 4, Realfagbygget

 

Committee:

Forsker Anna Nele Meckler, Institutt for geovitenskap

Professor Haflidi Haflidason, Institutt for geovitenskap

Professor Kerim Hestnes Nisancioglu, Institutt for geovitenskap

Jan
25
Fri
2019
Internal local economy status meetings for PI’s prior to reporting 54 month
Jan 25 all-day

Internal local economy status meetings for PI’s prior to reporting 56 month.

See slides from Hege from May meeting in Copenhagen 03.05.18-Ice2Ice-Adm.meeting

 

@Jens and Bo see the local NBI  Reporting calendar NBI-2019 towards the 54 month report

 

Jan
31
Thu
2019
DMI/NBI meeting @DMI
Jan 31 @ 09:00 – 12:00
The next ice2ice NBI/DMI meeting will take place the 31st of January 09-12 in room Daneborg, DMI and be a celebration of the great research we have conducted within ice2ice in 2018.
Thus we would like you to present (if you haven’t done so already) your latest (submitted or published or in prep) ice2ice article (see list below for all published publications 2018).
Please sign up for the meeting here by the 17th January, and also add the title of your presentation.
Merry Christmas
Bo, Jens, Peter and Helle
Feb
15
Fri
2019
PhD defense – Henrik Sadatzki @ Auditorium 4, Realfagbygget
Feb 15 @ 10:15

Defence

 MSc. Henrik Sadatzki will defend his ph.d.

 

Time: Friday 15. February, at 10.15h

Venue: Auditorium 4, Realfagbygget

 

Titel of the thesis:

Sea ice variability in the Nordic Seas over Dansgaard–Oeschger climate cycles during the last glacial – A biomarker approach

 

Opponent:

Professor, ph.d. Jerry McManus

Department of Earth and Environmental Sciences,

Columbia University, Lamont-Doherty Earth Observatory, USA

 

Opponent:

Førsteamanuensis, ph.d. Christof Pearce

Department Of Geoscience, Aarhus University, Danmark

 

Member in the comitee:

Førsteamanuensis, ph.d. Anna Nele Meckler

Institutt for geovitenskap, Universitet i Bergen

Feb
18
Mon
2019
PhD defense- Martin Olesen
Feb 18 @ 09:15 – 13:00

Martin Olesen will be having his PhD defense on Monday 18 February at 9:15, in room 008, Tagensvej 16.

Martin´s PhD thesis is titled: High resolution climate simulation. Methods for improving and customising climate information with focus on outreach and uncertainty assessment.

Abstract: Application of a single high resolution regional climate model (RCM) simulation for Greenland implies detailed information on the model performance compared to in situ observations and other RCMs. Projections of future climate change based on an ensemble of climate models are more robust than estimates based on a single model. In this thesis a statistical method to better frame results based on the RCM HIRHAM5 is utilized to assess uncertainties of projected climate change results. Expected future climate changes and associated uncertainties in Greenland are estimated for the periods 2031-2050 and 2081-2100. This analysis is based on HIRHAM5 at a horizontal resolution of approximately 5.5 km, emission scenarios used by IPCC and on European regional climate studies (EURO-CORDEX). Using HIRHAM5 simulations over Greenland in combination with an ensemble of coarser RCM simulations from a different geographical setting; EURO-CORDEX, we investigate to what extent the uncertainty of projected high-resolution climate change can be evaluated from corresponding temperature spread in a wider set of global climate models (GCMs), CMIP5. Furthermore, HIRHAM5 is compared with in situ observation records through spatially linked correlated patterns for temperature and precipitation. Improved climate information is achieved by combining long weather records from the Greenlandic coastal stations and proxy measurements of temperature and solid accumulation from deep ice cores and HIRHAM5 simulations. HIRHAM5 provides physically consistent information of temperature, precipitation, snow fall, melt, evaporation and surface mass balance (SMB) for the period 1980-2014. Our proposed uncertainty assessment method establishes a foundation on which high-resolution and relative costly regional climate projections in general can be assessed. Also when using only a single RCM without the presence of analogous downscaling experiments with other RCMs and GCMs, the uncertainty assessment is relying on already existing information from CMIP5. Thus, the uncertainty of a wide range of climate indices that scale with temperature can be evaluated and quantified through the inter-model temperature spread within CMIP5. Changes in growing season, number of frost days and consecutive dry days are presented as index examples. This investigation shows with high confidence that HIRHAM5 is representative of the ensemble of RCMs within EURO-CORDEX. By relating large scale correlations of various climate variables deduced from HIRHAM5, observed temperature and precipitation in situ records are prolonged 500 years back in time based on proxy data from deep ice cores. SMB for selected drainage basins on the Greenland ice sheet and for the Renland ice cap are reconstructed and show decreasing trend lines towards present. The SMB for the drainage basin nearest Tasiilaq, decreases from + 0.5 mm weq/yr for 1898-2014 to -5.4 mm weq/yr in 1980-2014. Correspondingly, the SMB for the drainage basin nearest Danmarkshavn decreases from -0.3 mm weq/yr for 1950-2014 to -1.1 mm weq/yr in 1980-2014, and the SMB of the Renland ice cap decreases from +2.4 mm weq/yr for 1950-2007 to -4.7 mm weq/yr in 1980-2007. Finally, the correlation patterns of temperature and precipitation illustrate the coverage of correlated weather stations and ice core drill site locations across Greenland. In situ observation records reflect with high confidence the spatial correlation patterns calculated from HIRHAM5 for both temperature and precipitation.

Supervisor
Prof. Jens Hesselbjerg Christensen, Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen
Prof. Eigil Kaas, Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen
Peter Lang Langen, Research and Development, Danish Meteorological Institute

Assessment Committee
Aslak Grinsted, Physics of Ice, Climate and Earth, Niels Bohr Institute
Prof. Dr. Daniela Jacob, GERICS, Institute Helmholtz-Zentrum Geesthacht
Research Prof. Tim Carter, Finnish Environment Institute

 

Feb
21
Thu
2019
PI meeting @CPH-DMI
Feb 21 – Feb 22 all-day
Feb
22
Fri
2019
DO workshop @CPH
Feb 22 @ 09:00 – 12:00

A small workshop with the aim to synthesize marine and ice core data using the new MIS 3 tephra synchronisation points and discuss possible timings, a sort of follow up on the DO meeting we had in 2016.