Luke Gregor

Luke Gregor
ETH Zurich | ETH Zürich · Department of Environmental Systems Science

PhD
Surface ocean extremes! Marine heatwaves and Ocean acidification extreme events.

About

35
Publications
16,544
Reads
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1,561
Citations
Introduction
I am an oceanographer based in Zürich, Switzerland. My work combines the exciting field of machine learning with earth system science, particularly the marine carbonate system. In the past, my work has ranged from the measurement of CO2 at sea and the processing of these samples in the laboratory, data management and quality control. Now, I work on machine learning products that estimate the amount of CO2 that the ocean is taking up from satellites. In my work at ETH, I am using these CO2 estimates to look at the changes in the ocean's acidity (pH) and where and when this coincides with extreme warming events. On the side, I dabble in Python and have created tools that are designed to streamline the processing of raw scientific data to being publication-ready.
Additional affiliations
April 2019 - present
ETH Zurich
Position
  • PostDoc Position
September 2017 - March 2019
Council for Scientific and Industrial Research, South Africa
Position
  • PostDoc Position
Education
March 2013 - March 2017
University of Cape Town
Field of study
  • Physical Oceanography

Publications

Publications (35)
Article
Full-text available
Over the last decade, advanced statistical inference and machine learning have been used to fill the gaps in sparse surface ocean CO2 measurements (Rödenbeck et al., 2015). The estimates from these methods have been used to constrain seasonal, interannual and decadal variability in sea–air CO2 fluxes and the drivers of these changes (Landschützer e...
Article
Full-text available
Underwater gliders have become widely used in the last decade. This has led to a proliferation of data and the concomitant development of tools to process the data. These tools are focused primarily on converting the data from its raw form to more accessible formats and often rely on proprietary programing languages. This has left a gap in the proc...
Article
Full-text available
Resolving and understanding the drivers of variability of CO2 in the Southern Ocean and its potential climate feedback is one of the major scientific challenges of the ocean-climate community. Here we use a regional approach on empirical estimates of pCO2 to understand the role that seasonal variability has in long-term CO2 changes in the Southern...
Article
Full-text available
Autonomous platforms will begin to address the space-time gaps required to improve estimates of phytoplankton distribution, which will aid in the quantification of baseline conditions necessary to detect long-term trends that can be attributed to factors such as climate change. However, there is a need for high quality controlled and verified datas...
Article
Full-text available
The Southern Ocean (SO) contributes most of the uncertainty in contemporary estimates of the mean annual flux of carbon dioxide CO2 between the ocean and the atmosphere. Attempts to reduce this uncertainty have aimed at resolving the seasonal cycle of the fugacity of CO2 (fCO2). We use hourly CO2 flux and driver observations collected by the combin...
Article
Full-text available
We use a statistical emulation technique to construct synthetic ensembles of global and regional sea‐air carbon dioxide (CO2) flux from four observation‐based products over 1985–2014. Much like ensembles of Earth system models that are constructed by perturbing their initial conditions, our synthetic ensemble members exhibit different phasing of in...
Article
Full-text available
Plain Language Summary The global ocean is experiencing major changes due to human‐made carbon emissions and climate change, leading to a warming ocean with increasing acidity and declining oxygen. On top of these long‐term changes in the ocean are short‐term extreme events, such as marine heatwaves. These extreme events quickly change the ocean st...
Preprint
Full-text available
The Southern Ocean is a complex system yet is sparsely sampled in both space and time. These factors raise questions about the confidence in present sampling strategies and associated machine learning (ML) reconstructions. Previous studies have not yielded a clear understanding of the origin of uncertainties and biases for the reconstructions of th...
Article
Full-text available
p>Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize datasets...
Preprint
Full-text available
Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets...
Article
Full-text available
Air–sea flux of carbon dioxide (CO2) is a critical component of the global carbon cycle and the climate system with the ocean removing about a quarter of the CO2 emitted into the atmosphere by human activities over the last decade. A common approach to estimate this net flux of CO2 across the air–sea interface is the use of surface ocean CO2 observ...
Preprint
Full-text available
Air-sea flux of carbon dioxide (CO2) is a critical component of the global carbon cycle and the climate system with the ocean removing about a quarter of the CO2 emitted into the atmosphere by human activities over the last decade. A common approach to estimate this net flux of CO2 across the air-sea interface is the use of surface ocean CO2 observ...
Article
Full-text available
Ocean acidification has profoundly altered the ocean's carbonate chemistry since preindustrial times, with potentially serious consequences for marine life. Yet, no long-term, global observation-based data set exists that allows us to study changes in ocean acidification for all carbonate system parameters over the last few decades. Here, we fill t...
Technical Report
Full-text available
Full report available from https://unesdoc.unesco.org/ark:/48223/pf0000376708.locale=en doi:10.25607/h0gj-pq41
Article
Full-text available
Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we de...
Preprint
Full-text available
Ocean acidification has altered the ocean's carbonate chemistry profoundly since preindustrial times, with potentially serious consequences for marine life. Yet, no long-term global observation-based data set exists that permits to study changes in ocean acidification for all carbonate system parameters over the last few decades. Here, we fill this...
Data
An update to the original CSIR-ML6 method. The following changes have been made: SOCATv2020 is used; ERA5 wind data and MSLP are used (instead of ERA interim); SODA salinity is used instead of EN4 salinity. Please cite the dataset as well as the original publication (https://doi.org/10.5194/gmd-12-5113-2019).
Poster
Full-text available
The oceans have been taking up anthropogenic CO2 leading to an increase in the ocean’s acidity. This could have a profound impact on marine life, particularly shell- and coral-forming calcifying organisms. Monitoring and predicting the acidification stress that marine organisms face is thus important and can help build resilience in related industr...
Code
GliderTools is a Python 3.6+ package designed to process data from the first level of processing to a science ready dataset. The package is designed to easily import data to a standard column format (e.g. numpy, pandas, xarray). The following functions are included in the package: cleaning and smoothing functions (as secondary quality control; an o...
Article
Full-text available
Air-sea and air-sea-ice fluxes in the Southern Ocean play a critical role in global climate through their impact on the overturning circulation and oceanic heat and carbon uptake. The challenging conditions in the Southern Ocean have led to sparse spatial and temporal coverage of observations. This has led to a “knowledge gap” that increases uncert...
Preprint
Full-text available
Over the last decade, advanced statistical inference and machine learning have been used to fill the gaps in sparse surface ocean CO 2 measurements (Rödenbeck et al. 2015). The estimates from these methods have been used to constrain seasonal, interannual and decadal variability in sea­air CO 2 fluxes and the drivers of these changes (Landschützer...
Code
Quenching correction method used in Thomalla et al. (2017) with example data and script. CITE AS: Thomalla, S. J., Moutier, W., Ryan-Keogh, T. J., Gregor, L., & Schütt, J. (2017). An optimized method for correcting fluorescence quenching using optical backscattering on autonomous platforms. Limnology and Oceanography: Methods. https://doi.org/10.1...
Article
Full-text available
The Southern Ocean accounts for 40 % of oceanic CO2 uptake, but the estimates are bound by large uncertainties due to a paucity in observations. Gap-filling empirical methods have been used to good effect to approximate pCO2 from satellite observable variables in other parts of the ocean, but many of these methods are not in agreement in the Southe...
Preprint
Full-text available
Machine learning methods (support vector regression and random forest regression) were used to map gridded estimates of ΔpCO2 in the Southern Ocean from SOCAT v3 data. A low (1° × monthly) and high (0.25° × 16-day) resolution implementation of each of these methods as well as the SOM-FFN method of Landschützer et al. (2014) were added to a five mem...
Preprint
Full-text available
The Southern Ocean accounts for 40 % of oceanic CO2 uptake, but the estimates are bound by large uncertainties due to a paucity in observations. Gap filling empirical methods have been used to good effect to approximate pCO2 from satellite observable variables in other parts of the ocean, but many of these methods are not in agreement in the Southe...
Article
Full-text available
The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values rela...
Working Paper
Full-text available
The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.5 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.4 million fCO2 values rela...
Article
In this study we use the southern Benguela upwelling system to investigate the role of nutrient and carbon stoichiometry on carbonate dynamics in eastern boundary upwelling systems. Six months in 2010 were sampled along a cross-shelf transect. Data were classified into summer, autumn, and winter. Nitrate, phosphate, dissolved inorganic carbon, and...
Article
Full-text available
This study was undertaken to characterise the seasonal cycle of air-sea fluxes of carbon dioxide (CO2) in the southern Benguela upwelling system off the South African west coast. Samples were collected from six monthly cross-shelf cruises in the St. Helena Bay region during 2010. CO2 fluxes were calculated from pCO2 derived from total alkalinity an...

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Projects

Projects (3)
Project
Global ocean carbon partial pressure and flux estimates using an ensemble of 6 machine learning methods. Latest version: https://doi.org/10.6084/m9.figshare.12652100 This project will be maintained and updated over a longer term basis.
Archived project
To establish an understanding and baseline of the seasonal marine carbonate cycle and nutrient cycling in the Southern Benguela region. This project was a part of Luke Gregor's masters thesis