51171
2018
2018
eng
12076
12084
9
21
45
article
American Geophysical Union
Washington
1
--
2018-10-31
--
Regional Changes in the Mean Position and Variability of the Tropical Edge
Recent studies indicate that the tropical belt has been expanding during recent decades, which can significantly influence precipitation in subtropical climates. Often the location of the tropical border is identified using the Hadley cell edge (HCE) or the subtropical jet stream (STJ), but most studies concentrated on the zonal-mean state, thereby missing regional impacts. Here we detect longitudinal-resolved trends in STJ cores and HCEs over 1979-2016 in both hemispheres at a higher spatial and temporal resolution than previous studies. Besides pronounced regional trend differences in both sign and magnitude, we show that winter HCE and STJ variability increased in the Mediterranean region and decreased over the American and Asian continents. Rainfall variability in these regions changed likewise, and most of those changes can be explained by changes in HCE/STJ variability. This highlights the importance of understanding future tropical belt changes both regionally and in terms of variability. Plain Language Summary We applied a new network-based method to detect motion of the tropical climate border with longitudinal resolution. Depending on the longitudinal position, there are differences in both direction and magnitude of the border motion. In addition, we demonstrate that the rainfall variability is increasing in the Mediterranean region and decreasing over the American and Asian continents, which can be explained by the variability of the tropical belt location.
Geophysical research letters
10.1029/2018GL079911
0094-8276
1944-8007
wos:2018
WOS:000451832600062
Totz, S (reprint author), Potsdam Inst Climate Impact Res PIK, Potsdam, Germany.; Totz, S (reprint author), Univ Potsdam, Dept Phys, Potsdam, Germany., sonja.totz@pik-potsdam.de
German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF) [01LN1304A]; European Regional Development Fund (ERDF)European Union (EU); Land Brandenburg
2021-06-30T08:16:21+00:00
sword
importub
filename=package.tar
c4e0580409caf3191bfc3db0b3fe0389
false
true
Sonja Juliana Totz
Stefan Petri
Jascha Lehmann
Dim Coumou
Geowissenschaften
Institut für Geowissenschaften
Referiert
Import
Green Open-Access
52172
2017
2017
eng
12418
12426
9
44
article
American Geophysical Union
Washington
1
--
2018-11-21
--
Winter precipitation forecast in the European and mediterranean regions using cluster analysis
The European climate is changing under global warming, and especially the Mediterranean region has been identified as a hot spot for climate change with climate models projecting a reduction in winter rainfall and a very pronounced increase in summertime heat waves. These trends are already detectable over the historic period. Hence, it is beneficial to forecast seasonal droughts well in advance so that water managers and stakeholders can prepare to mitigate deleterious impacts. We developed a new cluster-based empirical forecast method to predict precipitation anomalies in winter. This algorithm considers not only the strength but also the pattern of the precursors. We compare our algorithm with dynamic forecast models and a canonical correlation analysis-based prediction method demonstrating that our prediction method performs better in terms of time and pattern correlation in the Mediterranean and European regions.
Geophysical research letters
10.1002/2017GL075674
0094-8276
1944-8007
wos:2017
WOS:000422954700012
Cohen, J (reprint author), Atmospher & Environm Res Inc, Lexington, MA 02421 USA., jcohen@aer.com
German Federal Ministry of Education and Research [01LN1304A]; National Science Foundation [AGS-1303647, PLR-1504361]; National Science Foundation climate dynamics program [AGS-1622985]; National Science Foundation Large-Scale and Climate Dynamics Program [AGS-1303647, AGS-1303604]; National Science Foundation Division of Polar Programs [PLR-1504361]
2021-10-13T06:57:01+00:00
sword
importub
filename=package.tar
f2e3c96f9e181600ccaf0a6123226e98
Cohen, Judah
false
true
Sonja Juliana Totz
Eli Tziperman
Dim Coumou
Karl Pfeiffer
Judah Cohen
eng
uncontrolled
precipitation anomaly
eng
uncontrolled
seasonal forecast
eng
uncontrolled
cluster analysis
Geowissenschaften
Institut für Geowissenschaften
Referiert
Import
Bronze Open-Access
53506
2018
2018
eng
665
679
15
2
11
article
Copernicus
Göttingen
1
2018-02-22
2018-02-22
--
The dynamical core of the Aeolus 1.0 statistical-dynamical atmosphere model
Here, we present novel equations for the large-scale zonal-mean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0. The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications.
Geoscientific model development : an interactive open access journal of the European Geosciences Union
validation and parameter optimization
10.5194/gmd-11-665-2018
1991-959X
1991-9603
wos:2018
WOS:000425773000001
Totz, S (reprint author), Leibniz Fdn, Potsdam Inst Climate Impact Res PIK, Potsdam, Germany.; Totz, S (reprint author), Potsdam Univ, Dept Phys, Potsdam, Germany., sonja.totz@pik-potsdam.de
German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF) [01LN1304A]; Government of the Russian Federation [14.Z50.31.0033]; European Regional Development Fund (ERDF)European Union (EU); German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF); Land Brandenburg
2022-01-19T10:09:22+00:00
sword
importub
filename=package.tar
fe86b27ed10b868a62827226adc9ec37
Totz, Sonja
false
true
Sonja Juliana Totz
Alexey V. Eliseev
Stefan Petri
Michael Flechsig
Levke Caesar
Vladimir Petoukhov
Dim Coumou
Physik
Institut für Physik und Astronomie
Referiert
Import
Gold Open-Access
DOAJ gelistet
46976
2018
2020
eng
19
962
postprint
1
2020-07-01
2020-07-01
--
Control of transversal instabilities in reaction-diffusion systems
In two-dimensional reaction-diffusion systems, local curvature perturbations on traveling waves are typically damped out and vanish. However, if the inhibitor diffuses much faster than the activator, transversal instabilities can arise, leading from flat to folded, spatio-temporally modulated waves and to spreading spiral turbulence. Here, we propose a scheme to induce or inhibit these instabilities via a spatio-temporal feedback loop. In a piecewise-linear version of the FitzHugh-Nagumo model, transversal instabilities and spiral turbulence in the uncontrolled system are shown to be suppressed in the presence of control, thereby stabilizing plane wave propagation. Conversely, in numerical simulations with the modified Oregonator model for the photosensitive Belousov-Zhabotinsky reaction, which does not exhibit transversal instabilities on its own, we demonstrate the feasibility of inducing transversal instabilities and study the emerging wave patterns in a well-controlled manner.
Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
10.25932/publishup-46976
urn:nbn:de:kobv:517-opus4-469762
1866-8372
online registration
New Journal of Physics 20 (2018) 053034 DOI: 10.1088/1367-2630/aabce5
053034
<a href="http://publishup.uni-potsdam.de/52903">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
CC-BY - Namensnennung 4.0 International
Sonja Juliana Totz
Jakob Löber
Jan Frederik Totz
Harald Engel
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
962
eng
uncontrolled
traveling waves
eng
uncontrolled
control
eng
uncontrolled
transversal instabilities
Physik
open_access
Mathematisch-Naturwissenschaftliche Fakultät
Referiert
Open Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/46976/pmnr962.pdf
52418
2018
2018
eng
1275
1294
20
4
51
article
Springer
New York
1
2017-11-03
2017-11-03
--
Comparison of the effect of land-sea thermal contrast on interdecadal variations in winter and summer blockings
The influence of winter and summer land-sea surface thermal contrast on blocking for 1948-2013 is investigated using observations and the coupled model intercomparison project outputs. The land-sea index (LSI) is defined to measure the changes of zonal asymmetric thermal forcing under global warming. The summer LSI shows a slower increasing trend than winter during this period. For the positive of summer LSI, the EP flux convergence induced by the land-sea thermal forcing in the high latitude becomes weaker than normal, which induces positive anomaly of zonal-mean westerly and double-jet structure. Based on the quasiresonance amplification mechanism, the narrow and reduced westerly tunnel between two jet centers provides a favor environment for more frequent blocking. Composite analysis demonstrates that summer blocking shows an increasing trend of event numbers and a decreasing trend of durations. The numbers of the short-lived blocking persisting for 5-9 days significantly increases and the numbers of the long-lived blocking persisting for longer than 10 days has a weak increase than that in negative phase of summer LSI. The increasing transient wave activities induced by summer LSI is responsible for the decreasing duration of blockings. The increasing blocking due to summer LSI can further strengthen the continent warming and increase the summer LSI, which forms a positive feedback. The opposite dynamical effect of LSI on summer and winter blocking are discussed and found that the LSI-blocking negative feedback partially reduces the influence of the above positive feedback and induce the weak summer warming rate.
Climate dynamics : observational, theoretical and computational research on the climate system
10.1007/s00382-017-3954-9
0930-7575
1432-0894
wos:2018
WOS:000439440200001
Huang, JP (reprint author), Lanzhou Univ, Key Lab Semiarid Climate Change, Coll Atmospher Sci, Minist Educ, Lanzhou 73000, Gansu, Peoples R China., hjp@lzu.edu.cn
National Science Foundation of ChinaNational Natural Science Foundation of China [41521004, 41705047]; Foundation of Key Laboratory for Semi-Arid Climate Change of the Ministry of Education in Lanzhou University; China 111 project [B13045]; Foundation of Key Laboratory for Semi-Arid Climate Change of the Ministry of Education in Lanzhou University from the Fundamental Research Funds for the Central Universities [lzujbky-2017-bt04]; German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF) [01LN1304A]
2021-10-27T14:35:58+00:00
sword
importub
filename=package.tar
3bc115c87f91d7f19f6242d2b6ffac39
Huang, Jianping
false
true
Yongli He
Jianping Huang
Dongdong Li
Yongkun Xie
Guolong Zhang
Yulei Qi
Shanshan Wang
Sonja Juliana Totz
eng
uncontrolled
Land-sea thermal contrast
eng
uncontrolled
Blocking
eng
uncontrolled
Asymmetric warming
eng
uncontrolled
Double-jet
Physik
Institut für Physik und Astronomie
Referiert
Import
52903
2018
2018
eng
16
20
article
IOP Publ. Ltd.
Bristol
1
2018-05-11
2018-05-11
--
Control of transversal instabilities in reaction-diffusion systems
In two-dimensional reaction-diffusion systems, local curvature perturbations on traveling waves are typically damped out and vanish. However, if the inhibitor diffuses much faster than the activator, transversal instabilities can arise, leading from flat to folded, spatio-temporally modulated waves and to spreading spiral turbulence. Here, we propose a scheme to induce or inhibit these instabilities via a spatio-temporal feedback loop. In a piecewise-linear version of the FitzHugh-Nagumo model, transversal instabilities and spiral turbulence in the uncontrolled system are shown to be suppressed in the presence of control, thereby stabilizing plane wave propagation. Conversely, in numerical simulations with the modified Oregonator model for the photosensitive Belousov-Zhabotinsky reaction, which does not exhibit transversal instabilities on its own, we demonstrate the feasibility of inducing transversal instabilities and study the emerging wave patterns in a well-controlled manner.
New journal of physics : the open-access journal for physics
10.1088/1367-2630/aabce5
1367-2630
wos:2018
053034
WOS:000450713800005
Totz, JF (reprint author), Tech Univ Berlin, Inst Theoret Phys, EW 7-1,Hardenbergstr 36, D-10623 Berlin, Germany., sonja.totz@pik-potsdam.de; jakob@physik.tu-berlin.de; jantotz@itp.tu-berlin.de; h.engel@physik.tu-berlin.de
German Science Foundation (DFG)German Research Foundation (DFG) [GRK1558]
2021-12-01T09:17:15+00:00
sword
importub
filename=package.tar
edb7bdbd4be9e3514e0ce3fcc4bde63e
<a href="https://doi.org/10.25932/publishup-46976">Zweitveröffentlichung in der Schriftenreihe Postprints der Universität Potsdam : Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe ; 962 </a>
false
true
CC-BY - Namensnennung 4.0 International
Sonja Juliana Totz
Jakob Löber
Jan Frederik Totz
Harald Engel
eng
uncontrolled
traveling waves
eng
uncontrolled
control
eng
uncontrolled
transversal instabilities
Physik
Institut für Physik und Astronomie
Referiert
Import
Gold Open-Access
DOAJ gelistet
50210
2019
2019
eng
1
12
12
1
26
article
Copernicus
Göttingen
1
--
2019-02-18
--
Exploring the sensitivity of Northern Hemisphere atmospheric circulation to different surface temperature forcing using a statistical-dynamical atmospheric model
Climate and weather conditions in the mid-latitudes are strongly driven by the large-scale atmosphere circulation. Observational data indicate that important components of the large-scale circulation have changed in recent decades, including the strength and the width of the Hadley cell, jets, storm tracks and planetary waves. Here, we use a new statistical-dynamical atmosphere model (SDAM) to test the individual sensitivities of the large-scale atmospheric circulation to changes in the zonal temperature gradient, meridional temperature gradient and global-mean temperature. We analyze the Northern Hemisphere Hadley circulation, jet streams, storm tracks and planetary waves by systematically altering the zonal temperature asymmetry, the meridional temperature gradient and the global-mean temperature. Our results show that the strength of the Hadley cell, storm tracks and jet streams depend, in terms of relative changes, almost linearly on both the global-mean temperature and the meridional temperature gradient, whereas the zonal temperature asymmetry has little or no influence. The magnitude of planetary waves is affected by all three temperature components, as expected from theoretical dynamical considerations. The width of the Hadley cell behaves nonlinearly with respect to all three temperature components in the SDAM. Moreover, some of these observed large-scale atmospheric changes are expected from dynamical equations and are therefore an important part of model validation.
Nonlinear processes in geophysics
10.5194/npg-26-1-2019
1023-5809
1607-7946
wos:2019
WOS:000459029000001
Totz, S (reprint author), Leibniz Assoc, Potsdam Inst Climate Impact Res PIK, Potsdam, Germany.; Totz, S (reprint author), Univ Potsdam, Dept Phys, Potsdam, Germany., totz@pik-potsdam.de
German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF) [01LN1304A]; European Regional Development Fund (ERDF)European Union (EU); German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF); state of Brandenburg
2021-04-07T08:48:19+00:00
sword
importub
filename=package.tar
b9b6ca71a1070089f8ff6ef1862d85a0
false
true
CC-BY - Namensnennung 4.0 International
Sonja Juliana Totz
Stefan Petri
Jascha Lehmann
Erik Peukert
Dim Coumou
Geowissenschaften
Institut für Geowissenschaften
Referiert
Import
Gold Open-Access
DOAJ gelistet
41872
2018
2018
2018
eng
xii, 166
doctoralthesis
1
--
--
2018-08-23
Modeling and data analysis of large-scale atmosphere dynamics associated with extreme weather
In the last decades the frequency and intensity of extreme weather events like heat waves and heavy rainfall have increased and are at least partly linked to global warming. These events can have a strong impact on agricultural and economic production and, thereby, on society. Thus, it is important to improve our understanding of the physical processes leading to those extreme events in order to provide accurate near-term and long-term forecasts. Thermodynamic drivers associated with global warming are well understood, but dynamical aspects of the atmosphere much less so. The dynamical aspects, while less important than the thermodynamic drivers in regards to large-scale and long-time averaged effects, play a critical role in the formation of extremes.
The overall aim of this thesis is to improve our understanding of patterns, variability and trends in the global atmospheric circulation under a changing climate. In particular, in this dissertation I developed two new data-driven methods to quantitatively describe the dynamics of jet streams, Hadley cells and storm tracks. In addition, I introduce and validate a new statistical-dynamical atmosphere model that can be used to efficiently model the large-scale circulation.
First, I developed a scheme based on the Dijkstra ‘shortest-path’ algorithm to identify jet stream cores. Using reanalysis data, I found a significant change in jet stream strength and position over the last decades: Specifically, a decrease in wind speeds and a spatial shift toward the poles. This work also shows that the splitting or merging of the polar front jet stream and the subtropical jet stream depends on the season and longitudinal position. In a follow-up study, I analyzed trends in the latitudinal position of the poleward edge of the Hadley cell and subtropical jet stream core for all longitudes. These trends depend strongly on longitude and thus the impacts of tropical expansion might be pronounced in some regions and absent in others.
The second approach was to develop an empirical forecast method for European and Mediterranean winter precipitation. This prediction algorithm innovatively incorporates the spatial patterns of predictors in autumn using clustering analyses. I identified the most important precursors (snow cover in Eurasia, Barents and Kara sea ice concentrations as well as sea surface temperature in the Atlantic and Mediterranean region) for the precipitation prediction. This forecast algorithm had higher forecast skills than conventionally employed methods such as Canonical Correlation Analysis or operational systems using climate models.
The last approach was to examine the atmospheric circulation using the novel statisticaldynamical atmosphere model Aeolus. First, I validated the model’s depiction of the largescale circulation in terms of Hadley circulation, jet streams, storm tracks and planetary waves. To do so, I performed a parameter optimization using simulated annealing. Next, I investigated the sensitivity of the large-scale circulation to three different temperature components: global mean temperature, meridional temperature gradient and zonal temperature gradient. The model experiment showed that the strength of the Hadley cell, storm tracks and jet streams depend almost linearly on both the global mean temperature and the meridional temperature gradient, whereas the zonal temperature gradient is shown to have little or no influence. The magnitude of planetary waves is clearly affected by all three temperature components. Finally, the width of the Hadley cell behaves nonlinearly with respect to all three temperature components.
These findings might have profound consequences for climate modeling of the Mediterranean region. The latitudinal poleward trend of the Hadley cell edge position might become stronger under climate change according to the results with Aeolus. These changes would lead to a substantial reduction of the winter precipitation in the Mediterranean region. In this case seasonal empirical forecast methods, like the clustering-based prediction scheme, will play an important role for forecasting seasonal droughts in advance such that water managers and politicians can mitigate impacts.
In den letzten Jahren konnte ein Anstieg bei der Frequenz und Häufigkeit von Extremwetterereignissen wie Hitze- und Niederschlagsextreme beobachtet werden. Diese Ereignisse können einen massiven Einfluss auf die Landwirtschaft und ökonomische Produktion, und somit auf die gesamte Gesellschaft haben. Daher ist es wichtig, die zugrundeliegenden physikalischen Prozesse, die zu diesen Extremwetterereignissen führen, besser zu verstehen, um exakte Vorhersagen in naher und ferner Zukunft zu erstellen. Der Einfluss der thermodynamischen Kräfte auf den Klimawandel sind weitgehend bekannt, aber atmosphärischdynamische Aspekte weniger. Dynamische Aspekte, obwohl weniger wichtig bei großräumigen und langzeitgemittelten Effekten, spielen eine entscheidende Rolle zur Entstehung von Extremwetterereignissen.
Das übergeordnete Ziel dieser Dissertation ist es das Verständnis der Muster, Variabilität und Entwicklungen der globalen Atmosphärenzirkulation unter dem Klimawandel zu verbessern. Im Einzelnen entwickle ich in dieser Dissertation zwei neue datengetriebene Methoden, um quantitativ die Dynamik der Jetstreams, Hadley-Zellen und Sturmbahnen zu untersuchen. Außerdem wird ein neues statistisch-dynamisches Atmosphärenmodell vorgestellt und verifiziert, um effizient großräumige Zirkulationen zu simulieren.
Zunächst habe ich ein Programm basierend auf dem „kürzester Pfad“- Algorithmus von Dijkstra zur Detektion von Jetstreampfaden entwickelt. Unter Verwendung von Reanalysedaten lässt sich eine signifikante Änderung in der Stärke und dem Ort des Jetstreams über die letzten Jahrzehnte feststellen: Eine Abnahme der Windgeschwindigkeiten und eine räumliche Verschiebung in Richtung der Pole. Außerdem habe ich gezeigt, dass sich der polare und subtropische Jetstream je nach Jahreszeit und Längengrad vereinigen oder in zwei Jetstreams aufteilen. Weiterhin habe ich die Entwicklung der breitengradabhängigen Lage von Hadley-Zellen und der subtropischen Jetstreampfade analysiert. Die Trends hängen sehr stark vom Längengrad ab und daher sind die Auswirkungen der tropischen Ausdehnung in einigen Regionen sehr ausgeprägt und in anderen bleiben sie aus.
Ein zweiter Zugang umfasst die Entwicklung einer empirischen Vorhersagemethode für den winterlichen Niederschlag im Mittelmeer- und im europäischen Gebiet. Dieses Vorhersageprogramm bezieht innovativ die räumliche Verteilung von Prädiktoren im Herbst unter Verwendung der Clusteranalyse ein. Die wichtigsten Faktoren zur Niederschlagsvorhersage sind Schnee in Eurasien, Barents und Kara Eiskonzentrationen sowie Oberflächentemperatur des Meeres im Atlantik und im Mittelmeerraum. Dieses Vorhersageprogramm hat eine höhere Vorhersagegenauigkeit als herkömmliche Methoden wie beispielsweise Canonical Correlation Analysis oder operative Systeme unter Verwendung von Klimamodellen.
Der dritte Ansatz ist eine Untersuchung der Atmosphärenzirkulation mit dem statistischdynamischen Atmosphärenmodell Aeolus. Zunächst habe ich die Modelldarstellung der großräumigen Zirkulation in Bezug auf die Hadley Zirkulation, Jetstreams, Sturmbahnen und planetare Wellen validiert. Dafür führte ich eine Parameteroptimierung unter Verwendung von „Simulated Annealing“ durch. Im nächsten Schritt untersuchte ich die Sensitivität der großräumigen Zirkulation in Bezug auf drei verschiedene Temperaturkomponenten: globale mittlere Temperatur, meridionaler und zonaler Temperaturgradient. Das Modell zeigte, dass die Intensität der Hadley-Zelle, der Sturmaktivität, und der Jetstreams fast ausschließlich von der globalen Temperatur und dem meridionalen Temperaturgradienten abhängt, während der zonale Temperaturgradient kaum Einfluss hat. Die Stärke der planetaren Wellen wird von allen drei Komponenten beeinflusst. Auch die Breite der Hadley-Zelle verhält sich nichtlinear in Abhängigkeit der drei Temperaturkomponenten.
Diese Ergebnisse könnten weitreichende Konsequenzen für die Klimamodellierung des Mittelmeerraums haben. Der breitengradabhängige Trend der Hadley-Zellenflanke könnte unter dem Klimawandel steigen, gemäß den Ergebnissen von Aeolus. Diese Änderungen können zu einer deutlichen Reduktion des winterlichen Niederschlages im Mittelmeerraum führen. In diesem Fall werden saisonale empirische Vorhersagemodelle wie das Clusterbasierte Vorhersageprogramm eine große Rolle spielen, um saisonale Dürren frühzeitig vorhersagen zu können, damit Manager und Politiker frühzeitig Maßnahmen ergreifen können.
online registration
Dissertation, Universität Potsdam, 2018
Keine öffentliche Lizenz: Unter Urheberrechtsschutz
Sonja Juliana Totz
eng
uncontrolled
climate
Geowissenschaften
open_access
Institut für Physik und Astronomie
Universität Potsdam
Universität Potsdam