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Reconstructing Climate Using Ensemble Kalman Fitting (REUSE)

English title Reconstructing Climate Using Ensemble Kalman Fitting
Applicant Brönnimann Stefan
Number 162668
Funding scheme Project funding (Div. I-III)
Research institution Geographisches Institut Universität Bern
Institution of higher education University of Berne - BE
Main discipline Climatology. Atmospherical Chemistry, Aeronomy
Start/End 01.06.2016 - 30.11.2019
Approved amount 369'417.00
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All Disciplines (2)

Discipline
Climatology. Atmospherical Chemistry, Aeronomy
Meteorology

Keywords (6)

climate model simulations; climate dynamics; climate reconstructions; proxy data; data assimilation; past climate

Lay Summary (German)

Lead
Mit einer neuen Methode der Klimarekonstruktion, welche auf der Kombination von Klimaarchiven, Messungen, und Modellen beruht, wird das weltweite Klima monatlich über die letzten 400 Jahre rekonstruiert. Dies verspricht neue Einsichten zum Übergang des Klimas von der "Kleinen Eiszeit" in die heutige Warmzeit
Lay summary
Die Kenntnis der Klimavergangenheit ist unabdingbar zum besseren Verständnis der aktuellen und zukünftigen Veränderungen im Klimasystem. Allerdings ist vergangene Klimainformation oft sehr punktuell. Aussagen zu räumlichen Mustern oder Zirkulationsveränderungen sind nicht ohne weiteres möglich. In den letzten Jahren wurden neue numerische Techniken entwickelt, die es erlauben, spärliche Klimainformation der Vergangenheit zu verknüpfen mit Klimamodellsimulationen. Derartige Datenassimilationsmethoden liefern optimale Schätzungen der raum-zeilichen Variabilität des vergangenen Klimas, die gleichzeitig physikalisch konsistent und in Übereinstimmung mit der Klimainformation sind. Im Projekt REUSE wird ein solcher Datensatz erstellt. Ziel ist eine monatliche, globale, 3-dimensionale Rekonstruktion der Atmosphäre zurück bis 1600. Dazu werden Klimainformationen aus Messungen, historischen Dokumenten und Baumringen mit 30 Simulationen eines Klimamodells verknüpft. Die Methode ist in den Grundzügen vorhanden, muss aber angepasst und verfeinert werden, damit eine gute Rekonstruktion gelingen kann. Die Methode bringt gegenüber herkömmlichen Rekonstruktionsmethoden eine wesentliche Verbesserung; eine globale monatliche Klimarekonstruktion existiert bis anhin nicht. Anhand dieses Datensatzes soll der Übergang vom Klima der "Kleinen Eiszeit" zum modernen Klima genauer untersucht werden. Ein Fokus sind insbesondere dekadale Schankungen des Klimas und der grossräumigen atmosphärischen Zirkulation.
Direct link to Lay Summary Last update: 21.04.2016

Responsible applicant and co-applicants

Employees

Publications

Publication
Two types of North American droughts related to different atmospheric circulation patterns
Burgdorf Angela-Maria, Brönnimann Stefan, Franke Jörg (2019), Two types of North American droughts related to different atmospheric circulation patterns, in Climate of the Past, 15(6), 2053-2065.
Last phase of the Little Ice Age forced by volcanic eruptions
Brönnimann Stefan, Franke Jörg, Nussbaumer Samuel U., Zumbühl Heinz J., Steiner Daniel, Trachsel Mathias, Hegerl Gabriele C., Schurer Andrew, Worni Matthias, Malik Abdul, Flückiger Julian, Raible Christoph C. (2019), Last phase of the Little Ice Age forced by volcanic eruptions, in Nature Geoscience, 12(8), 650-656.
Impact of different estimations of the background-error covariance matrix on climate reconstructions based on data assimilation
Valler Veronika, Franke Jörg, Brönnimann Stefan (2019), Impact of different estimations of the background-error covariance matrix on climate reconstructions based on data assimilation, in Climate of the Past, 15(4), 1427-1441.
Causes for increased flood frequency in central Europe in the 19th century
Brönnimann Stefan, Frigerio Luca, Schwander Mikhaël, Rohrer Marco, Stucki Peter, Franke Jörg (2019), Causes for increased flood frequency in central Europe in the 19th century, in Climate of the Past Discussions, 1-21.
The longest homogeneous series of grape harvest dates, Beaune 1354-2018, and its significance for the understanding of past and present climate
Labbé Thomas, Pfister Christian, Brönnimann Stefan, Rousseau Daniel, Franke Jörg, Bois Benjamin (2019), The longest homogeneous series of grape harvest dates, Beaune 1354-2018, and its significance for the understanding of past and present climate, in Climate of the Past Discussions, 1-33.
Temps et climat en Suisse dans les années 1810 (Weather and climate in Switzerland in the 1810s)
BrönnimannStefan (2019), Temps et climat en Suisse dans les années 1810 (Weather and climate in Switzerland in the 1810s), in Annales Valaisannes, 2019, 49-60.
Reconstruction of Lamb weather type series back to the eighteenth century
Delaygue Gilles, Brönnimann Stefan, Jones Philip D., Blanchet Juliette, Schwander Mikhaël (2018), Reconstruction of Lamb weather type series back to the eighteenth century, in Climate Dynamics.
Climate from 1800 to 1970 in North America and Europe
Brönnimann Stefan, White Sam, Slonosky Victoria (2018), Climate from 1800 to 1970 in North America and Europe, Palgrave Macmillan UK, London, 309-320.
CH2018 – Climate Scenarios for Switzerland, Technical Report
CH2018 (2018), CH2018 – Climate Scenarios for Switzerland, Technical Report, National Centre for Climate Services, Zurich.
A monthly global paleo-reanalysis of the atmosphere from 1600 to 2005 for studying past climatic variations
Franke Jörg, Brönnimann Stefan, Bhend Jonas, Brugnara Yuri (2017), A monthly global paleo-reanalysis of the atmosphere from 1600 to 2005 for studying past climatic variations, in Scientific Data, 4, 170076-170076.

Collaboration

Group / person Country
Types of collaboration
OCCR, Univ. Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
NOAA/CIRES and Univ. Colorado, CDC United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
University of Maryland United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
University of Washington, USA United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Université Louvain-La Neuve Belgium (Europe)
- in-depth/constructive exchanges on approaches, methods or results
ACRE Initiative, UK Met Office Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Colloquium Climatology Individual talk From the Little Ice Age to the Present 19.09.2019 Bern, Switzerland Brönnimann Stefan;
Colloquium with Univ. Mainz Individual talk Paleoreanalysis – how to reconstruct global 3D climate 17.09.2019 Bern, Switzerland Brönnimann Stefan;
PAGES Workshop on Data Assimilation and Proxy System Modeling DAPS Talk given at a conference Data Assimilation Intercomparison Project (DAIP) 30.05.2019 College Park MD, United States of America Franke Jörg;
Colloquium in Climatology, Climate Impact and Remote Sensing Individual talk Optimizing a data assimilation method for climate reconstruction 27.03.2019 Bern, Switzerland Valler Veronika;
Swiss Geoscience Meeting, Bern, 1 December 2018 (Talk, Stefan Brönnimann) Talk given at a conference Climatic changes in Switzerland over the last 300 years 01.12.2018 Bern, Switzerland Brönnimann Stefan;
Mini-Workshop on Historical Climate Talk given at a conference A global palaeo reanalysis using early instrumental and documentary data in an off-line data assimilation approach 08.11.2018 Taipei, Taiwan Brönnimann Stefan;
Colloquium in Erath Sciences Individual talk Climate Reconstructions Using Data Assimilation 30.10.2018 Zurich, Switzerland Brönnimann Stefan;
Last Millennium Reanalysis Workshop Talk given at a conference Monthly global climate reconstructions: EKF400 03.10.2018 Boulder CO (by skype), United States of America Brönnimann Stefan;
EMS Assembly Poster Impact of different estimations of the background-error covariance matrix in a climate reconstruction 02.09.2018 Budapest, Hungary Valler Veronika;
17th Swiss Climate Summer School Poster Impact of different estimations of the background-error covariance matrix in a climate reconstruction 26.08.2018 Grindelwald, Switzerland Valler Veronika;
Colloque Giétro 1818 Talk given at a conference Climate in Switzerland in the Early 19th Century 14.06.2018 Le Châble, Switzerland Brönnimann Stefan;
19th Swiss Global Change Day Poster Improved estimation of background-error covariance matrix in climate reconstruction 19.04.2018 Bern, Switzerland Valler Veronika;
EGU General Assembly Poster Improved estimation of background-error covariance matrix in climate reconstruction 08.04.2018 Vienna, Austria Valler Veronika;
EGU Annual Assembly Talk given at a conference Expert selection vs. statistical screening – How to best choose input data for paleo-climatic reconstructions? Results from our Ensemble Kalman Fitting paleo-data-assimilation method 08.04.2018 Vienna, Austria Franke Jörg;
EGU Annual Assembly Poster Climate change detection and attribution using high resolution paleoclimate observations 08.04.2018 Vienna, Austria Franke Jörg;
Lamont/Doherty Earth Observation Lab Individual talk A global climate reconstruction using data assimilation 31.03.2018 Palisades, NJ, United States of America Brönnimann Stefan;
AMS NYC/Long Island Chapter Individual talk Learning From Past Weather 28.03.2018 New York, United States of America Brönnimann Stefan;
Reanalyses and Climate Services for Society Talk given at a conference Reanalysis Stories 14.12.2017 Bern, Switzerland Brönnimann Stefan;
5th Reanalysis Conference Talk given at a conference A global climate reconstruction using data assimilation 15.11.2017 Rome, Italy Brönnimann Stefan;
Seniorenuniversität Bern Talk given at a conference Wetterrekonstruktion: Von Lawinen und Vulkanen 29.09.2017 Bern, Switzerland Brönnimann Stefan;
TITAN Workshop Talk given at a conference Circulation change over the anthropocene 11.09.2017 Edinburgh, Great Britain and Northern Ireland Brönnimann Stefan;
16th International Swiss Climate Summer School Talk given at a conference High-Resolution Climate: Reanalyses and Weather Reconstructions 05.09.2017 Ascona, Switzerland Brönnimann Stefan;
16th Swiss Climate Summer School, Ascona Poster Global climate field reconstruction from 1600 to 2000 based on multi-proxy data and the Ensemble Kalman Fitting approach 03.09.2017 Ascona, Switzerland Valler Veronika;
1st PAGES DAPS workshop Talk given at a conference Data Assimilation in Paleosciences Reconstruction of Atmospheric and Surface Conditions 29.05.2017 Louvain-la-Neuve, Belgium Franke Jörg;
5th PAGES Open Science Meeting Poster Climate change detection and attribution using high resolution paleoclimate observations 09.05.2017 Zaragoza, Spain Franke Jörg;
5th PAGES Open Science Meeting Poster Global climate field reconstruction from 1600 to 2000 based on multi-proxy data and the Ensemble Kalman Fitting approach 09.05.2017 Zaragoza, Spain Valler Veronika;
5th PAGES Open Science Meeting, Zaragoza Talk given at a conference A monthly paleo-reanalysis based on instrumental measurements, historical documents and tree-ring data for the period 1600 to 2000 09.05.2017 Zaragoza, Spain Franke Jörg;
Emerging Applications of Data Assimilation in the Geosciences Talk given at a conference Tutorial Talk on Climatology 14.03.2017 Leiden, Netherlands Valler Veronika; Brönnimann Stefan;
FocusTerra Individual talk Was können wir vom «Jahr ohne Sommer» lernen? 13.10.2016 Zurich, Switzerland Brönnimann Stefan;
Colloquium, Université de Grenoble Individual talk Some Aspects of Atmospheric Circulation Change During the 20th century 20.09.2016 Grenoble, France Brönnimann Stefan;
Oeschger Centre Plenary Talk given at a conference New developments in global atmospheric reanalysis and some applications 15.09.2016 Bern, Switzerland Brönnimann Stefan;
ACRE Annual Assembly Talk given at a conference Tambora and the Year Without a Summer of 1816: A Perspective on Earth and Human Systems Science 20.06.2016 Maynooth, Ireland Brönnimann Stefan;
PAGES/VICS Workshop Talk given at a conference Tambora - What can we learn from the „Year Without a Summer“ of 1816? 06.06.2016 Palisades NJ, United States of America Brönnimann Stefan;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Symposium meteorological libraries/archives weather services Europe Workshop 24.10.2019 Vienna, Austria Brönnimann Stefan;
ISCM Conference Zurich Workshop 24.09.2019 Zurich, Switzerland Brönnimann Stefan;
Swiss Engineering STV – Sektion Berner Oberland: "Klima und Wetter im Laufe der Zeit" Talk 19.09.2019 Steffisburg, Switzerland Brönnimann Stefan;
Amtsleiterinnentreffen Liechtenstein: "Klimawandel: Vergangenheit – Zukunft - Massnahmen" Talk 13.09.2019 Bern, Switzerland Brönnimann Stefan;
Gemeindepräsidentenanlass: "Klimawandel in der Schweiz - Lehren aus der Vergangenheit und Ausblick in die Zukunft" Talk 17.10.2018 Bern, Switzerland Brönnimann Stefan;
Weiterbildungsanlass, Baudirektion St. Gallen: "Klimawandel in der Schweiz" Talk 10.09.2018 St. Gallen, Switzerland Brönnimann Stefan;


Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions Public "Sciene Talk" (interview), University Library Bern German-speaking Switzerland 2019
Media relations: radio, television The climate is warming faster than it has in the last 2,000 years several hundred media stories International 2019
Media relations: radio, television Volcanoes shaped the climate before humankind several hundred media stories International 2019

Associated projects

Number Title Start Funding scheme
188701 Daily Weather Reconstructions to Study Decadal Climate Swings 01.04.2020 Project funding (Div. I-III)
143219 Long-term changes of weather extremes in a large ensmble of climate model simulations (EXTRA-LARGE) 01.09.2013 Project funding (Div. I-III)
169676 Swiss Early Instrumental Measurements for Studying Decadal Climate Variability (CHIMES) 01.11.2016 Project funding (Div. I-III)
147659 Future and Past Solar Influence on the Terrestrial Climate II 01.01.2014 Sinergia

Abstract

Understanding the past behaviour of the climate system ideally relies on a comprehensive view of past climate states. However, paleoclimatology is often faced with a sparsity of proxies, and a comprehen-sive view is then only possible with audacious interpretation. In recent years, new numerical tech-niques have become available that derive a best estimate of the climate state by combining the real-world information from sparse proxy data with the physics of climate models. These data sets provide a physically consistent, spatially complete picture of the past climate system that is in agreement with the proxy records within their errors. In a just completed pilot project of the applicant, a 400-year long, monthly, global, 3-dimensional test data set was produced by assimilating historical instrumen-tal data, documentary evidence, and tree ring data into a large ensemble of climate model simulations using an off-line Ensemble Kalman Filter technique. While the feasibility of the approach and the usefulness of the resulting data set could be demonstrated, the potential still remains to be fully ex-ploited. The proposed project will create a new, 400-year data set through substantially improving the approach. It will systematically test some of the underlying assumptions, improve the incorporation of proxy data and their errors, optimize the specification of error covariances and provide a more sys-tematic validation. The resulting data set is expected to constitute a significant improvement over past reconstructions. The data will be used to study large-scale circulation changes associated with epi-sodes of slowed or accelerated warming, the transition from the Little Ice Age climate to the present climate, and the synchronism of northern and southern hemisphere, interannual-to-decadal climate.
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