Gas group
Bachelor project on instruments development for measuring the composition of the current and past atmosphere
We have a suite of new instruments that need development work and testing.
Projects can be on:
• Latest laser-based instruments for measuring trace gases in the atmosphere (e.g. CO2, CH4, N2O).
• New high resolution mass spectrometers.
• Development work on gas extraction from ice cores. (Sublimation system).
• Development work on isolating single atmospheric components.
Contact: Thomas Blunier (blunier@nbi.ku.dk)
Master project on high temporal resolution reconstruction of the paleo atmosphere
We developed a system for continuous gas measurements from ice cores. Here a stick of ice is melted continuously, gas from the past atmosphere contained in the ice is continuously extracted from the melt water and directed to measuring devices. In the ice expected being 1.5 million years old we expect about 700 kyr in only 100 m of ice core. Therefore, our system needs to be optimized for higher resolution. A focus is on the gas extraction, optimization of gas flow and the lining up of instruments. This is an experimental challenge that we need to address before the measuring campaign in fall 2025.
Contact: Thomas Blunier (blunier@nbi.ku.dk)
Master project on methane before 800 kyr BP
The oldest continuous ice core currently reaches back to 800 kyr BP. In the coming austral summer 2024/2025 the BE-OI core will be drilled to reach 1.5 million years, and that ice will come to Copenhagen in summer 2025.
We will, in international collaboration, analyse the core for the past atmospheric CH4 concentration among others. This will be the first time that such old ice will be analyses and we are thrilled to learn how the atmosphere has been composed at a time when the succession of glacials and interglacials was 40 kyr opposed to the current 100 kyr.
If you want to be part of an exciting measurement campaign, here is a one-time opportunity.
Figure 1: Red and blue, ice core reconstruction of atmospheric CO2 and temperature, respectively. White, proxy-based reconstruction of CO2. Black, sea level from dead sea cores.
Contact: Thomas Blunier (blunier@nbi.ku.dk).
Oxygen isotopes (of atmospheric oxygen)
The isotopic composition of atmospheric oxygen is changing over time due to fractionation in the biogeochemical cycle. Further processes in the stratosphere alter the isotopic composition due to exchange reactions with Ozone. Our new high-resolution mass spectrometer allows to measure not only “regular” isotopes but also tiny deviations in clumped isotopes where minor heavy isotopes are over represented.
The suite of isotope ratios we can measure with our new high resolution mass spectrometer d17O, d18O, D35, D36 allow:
1) Dating of old ice core through changes in the biosphere related to orbital variations.
2) Reconstruction of biospheric production of oxygen.
3) Changes in the oxidative capacity of the atmosphere.
Regardless of the focus, some development work on gas extraction and instrumentation will be part of the project, combined with a measurement campaign aimed at understanding the natural variability of the biosphere and atmosphere.
Figure 1: The oxygen cycle.
Contact: Thomas Blunier (blunier@nbi.ku.dk).
Ocean Noble Gas thermometer
The solubility of gases in water depends on the water temperature following Henry’s Law. In this project, we aim to reconstruct Mean Ocean Temperatures (MOT) using atmospheric noble gas measurements from old, archived air samples. This is possible because:
(i) The ocean and atmosphere form a closed system so that a change in noble gas concentration in the oceans is reflected in a similar but opposite change in the atmosphere.
(ii) Noble gases are inert. As such, atmospheric noble gas concentrations are driven solely by the solubility effect from MOT changes1.
MOT is a key parameter for studying the Earth's energy balance. We will focus on reconstructing MOT from preindustrial times (1850) to the present to infer the changes in the Earth's energy balance due to global warming caused by anthropogenic greenhouse gas emissions. This research will provide crucial insights into how fast the ocean is warming, which will affect predictions of sea level rise and help improve climate model predictions.
Earth's energy imbalance (EEI) is defined as the difference between the solar energy absorbed and the energy radiated back into space by the Earth. Anthropogenic greenhouse gas emissions since the onset of the Industrial Revolution are the primary driver of recent EEI. Currently the ocean acts as a buffer to global warming and absorbs about 93% of the excess energy from radiative imbalance2. Observational records of Ocean Heat Content (OHC) since 1960 show an energy uptake by the world's oceans of about 300 zeta (1021) Joules and an average ocean warming of 0.1 to 0.2 K over the last 60 years, contributing 4 cm to mean global sea level rise.
Accurate OHC/MOT estimates are necessary to determine EEI changes3. However, an accurate MOT time series from 1850 to the present does not exist because meaningful direct observations only began in the 1960s. Furthermore, accurate monitoring has only been possible since 20072,4,5. The project focuses on reconstructing changes in global OHC, MOT, and steric sea-level rise over the period from 1850 to the present. For that, we will measure mixing ratios of atmospheric noble gases (Kr/Ar, Xe/Ar, Kr/Xe) from a variety of historical archived air samples using our new Isotope Ratio Mass Spectrometry (IRMS, Nu Perspective) optimized for Noble Gas measurements. We have built a prototype system to extract air from these historical air archives and looking now for a motivated master student for system characterization and optimization. Further the student will measure Noble Gas mixing ratios on a variety of historic air containers and help with data interpretation. If you are interested in becoming part of the “gas lab crew” at PICE and working on Noble Gas measurements to quantify Ocean warming or if you have further questions about the project, you can contact:
Contact: Michael Döring (michael.doring@nbi.ku.dk)
Figure 1: Candidate sources of old air from left to right: 1) Rothamsted research is home to a long-term archive of soil, crops and manure samples dating back to the 1840s, and some has gas tight seals. 2) Glass fishing floats have been used since the mid-1700s and have been commercially manufactured since 1840. 3) Glass bricks has been mass produced since the early 1900s, and were preceded by Falconnier glass bricks invented in 1889. 4) Many historical scientific instruments, such as hydrometers, contain samples of old air.
- Keeling, R. F. et al. Tellus B Chem. Phys. Meteorol. (2004).
- Cheng, L. et al. Sci. Adv. (2017).
- Von Schuckmann, K. et al. Nat. Clim. Change (2016).
- Abraham, J. P. et al. Rev. Geophys. (2013).
- Cheng, L., et al. Science (2019).
Modelling the termination of the last Ice Age in Greenland with the Community Firn Model
Are you looking for an exciting Msc thesis project where you can combine your Python computational skills with inverse methods and state of the art datasets of N2 and Ar isotopes in order to look far back in Greenland's past climate? If you are fascinated by polar research and curious about climate change processes this may be a unique chance for you to join a dynamic group with decades of history in polar and ice core research.
You will be looking into the abrupt warming signals during the sudden end of the last Ice Age about 12,000 ago and using a state-of-the-art model of snow densification and gas diffusion you will work towards quantifying the magnitude and rapidity of the abrupt climate change during this time. We require that you are familiar with Python and you can expect your skills to get very sharp during the duration of the project. You will get hands-on experience with polar snow/firn modelling tools and high quality datasets of N2 and Ar isotopes from the air bubbles in the ancient ice. We are a very open and dynamic group with a variety of nationalities and backgrounds as well as a wide international network of collaborations.
Should you have any questions on the project feel free to contact: Vasileios Gkinis and Michael Döring
Recording the sound of ancient bubbles in ice cores
Msc Thesis Project: The sonic signature of ancient air bubbles in ice cores
Keywords: ice cores; paleoclimate; Greenland; polar research; Continuous Flow Analysis; sound measurements; total air content; Python; spectral analysis; bubbles
The air bubbles occluded in polar ice cores contain extremely valuable paleoclimatic information in the form of ancient air, whose composition can be determined in the lab yielding time series of gas concentrations in atmosphere spanning millennia. Another characteristic of the ancient air bubbles is their popping sound emission when ice core samples are being controllably melted for high-resolution Continuous Flow Analysis measurements.
We would like to investigate the audio signal of the “popping” bubbles. Our goal is to perform high quality sound recordings followed by spectral analysis of the bubble popping frequencies in order to infer how many and how large the bubbles are. Therefore, we offer a Master thesis project for a motivated student who will further develop the recording and melting system as well as work on the data analysis of the sounds recordings.
You can expect to gain skills in sound and bubble physics, sound recordings as well as high resolution ice core measurements. You will also work with noise filtering and spectral analysis techniques. Prior experience in data analysis with Python/Matlab is a plus. PICE is an active, multinational/multicultural group with plenty of learning opportunities.
We will be happy to hear from you!
Should you have any questions on the project feel free to contact: Vasileios Gkinis
Student Projects
