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14/05/2019 - Successful first research stay of our partners from University of Tsukuba at KIT

Group photo
Group photo on the rooftop. From left to right: Dominik, Akio, Mio, Julian, Jan, Takumi, Christian, Moritz

During the first week of May, we had the opportunity to welcome our research colleagues from University of Tsukuba (Japan), Mio Matsueda (Assistant Professor), Akio Yamagami (PostDoc), and Takumi Matsunobu (MSc Student), at KIT. Their stay was the kick-off visit in the framework of our two-year DAAD joint research project “Weather regimes in Europe and Asia: subseasonal predictability (WEASP)”, which aims to foster collaboration between our groups at University of Tsukuba and KIT.

The visit entailed numerous fruitful meetings, in which we discussed first results of our common research, exchanged expertise on open challenges, and ultimately defined specific goals and tasks we want to achieve during the upcoming year. More specifically, we advanced the two following main work packages: first, we will come up with a year-round definition of East Asian weather regimes, investigate their dynamical characteristics with a focus on diabatic outflow, and verify their predictability in subseasonal numerical weather models, similarly to what we already do for the Euro-Atlantic weather regimes. Considering the strongly varying and thus fascinating climate of Japan, which ranges from heavy snow falls triggered by the mixing of cold Siberian air masses with humid maritime air masses from the Subtropics to devastating Typhoons that regularly hit the island, this research may ultimately help to improve operational subseasonal forecasting in Japan. To this end, the knowledge of our Japanese colleagues about East Asian climate perfectly complements the dynamical, weather system-oriented expertise about weather regime life cycles at SPREADOUT. In a second work package, we will draw upon the strong technical and statistical expertise of our colleagues to verify the subseasonal predictability of year-round Euro-Atlantic weather regimes, which will be the foundation for many research goals of SPREADOUT. Beside these main topics, we exchanged further ideas related to ongoing work on extreme events in Japan, tropical influences on Japanese climate, and dynamical links between Euro-Atlantic and East Asian weather regimes. The diverse research topics of our guests from Tsukuba was also of interest in a number of side meetings with colleagues at IMK-TRO. As a final scientific highlight, the delegation from Japan presented highlights from their past and ongoing work in the “Karlsruhe Meteorologisches Kolloquium” (the IMK-wide external seminar): Mio presented some of his extensive work on the verification of medium-range predictability of Euro-Atlantic winter weather regimes and introduced the publicly available TIGGE and S2S museums. Akio continued with an overview of his research on the dynamics of extraordinary Arctic Cyclones and Takumi finished with his work on the predictability of a past heavy precipitation event over Japan.

Since this was the first longer visit of Europe for some of our guests, we of course did not want to miss out on introducing them to some of the natural and culinary beauties of Southern Germany. We thus went for a hike in the Black Forest on the sunny 1st of May, visited Heidelberg on a cold Sunday, and ate delicious local food in various restaurants in Karlsruhe, which included tasty asparagus, good beer, and a ride on the legendary slide in the “Badisch Brauhaus”. In return, Mio, Akio and Takumi told us a lot about their certainly different but very interesting culture, about their traditions, and about how science works in their country. After an intense week, we all agreed on the success of their stay and the potential of our collaboration. Therefore, we are excited to continue with our joint research project WEASP and hopefully exchange many new results when we from SPREADOUT will visit them in fall 2019.

For more information about the research of our colleagues, visit the webpage of Mio Matsueda’s group at University of Tsukuba. / DB


29/04/2019 - Spreadout at the S2S/TIGGE workshop at ECMWF in Reading, UK

Spreadout at ECMWF
Christian, Dominik, and Jan in front of the ECMWF building

We recently had the opportunity to attend the inspiring and perfectly organized "Workshop on predictability, dynamics and applications using the TIGGE and S2S ensembles" at the European Centre for Medium-Range Weather Forecast (ECMWF) in Reading (UK). The workshop gathered a diverse group of people from research, industry, and national weather services from all over the world who work with the two popular model intercomparison datasets for medium-range (TIGGE) and subseasonal (S2S) weather prediction.

Reading's busy morning traffic does not make it easy for the buses to reach the "Weather Centre", as the friendly Britains like to call it, on time. But with some patience and strengthened by a classic English breakfast, we succeeded and were ready to start the workshop. Jan and Christian both presented our operational weather regime forecast products. They showed their usefulness not only for operational weather forecasting but also for understanding how synoptic-scale processes, such as cloud-condensational heating in midlatitude cyclones, affect the subseasonal predictability of weather regime life cycles. Both contributions triggered lots of discussions with researchers working on large-scale dynamics, colleagues working on numerical model development, and forecasters seeking for better operational tools. Dominik presented an applied research project in cooperation with Remo Beerli (Axpo Solutions AG), which quantifies the skill of the ECMWF subseasonal model in predicting month-ahead, country-averaged surface weather over Europe after particularly strong and weak states of the stratospheric polar vortex during winter. Due to the sudden stratospheric warming at the beginning of this year and the failure of weather models (and thus the energy industry) to correctly predict its impact on surface weather, this contribution gained particular attention from energy meteorologists participating in the workshop, but also from model developers trying to better understand model biases associated with such dynamically complex events.

Numerous interesting contributions highlighted the great potential in using ensemble data for better predictions on subseasonal time scales. However, many studies also documented the lack of forecast skill for the midlatitudes beyond two weeks. It became obvious that models still struggle to fully exploit potential sources of extended range predictability (such as the stratosphere or the MJO). Working group discussions elaborated recommendations to the WMO WWRP/WCRP programs on how to make even better use of the TIGGE and S2S datasets and on the research needed to further improve numerical models. It clearly emerged that there is a need for a better understanding of the processes involved in teleconnections on subseasonal time scales and that the focus for the midlatitudes should be on large-scale regimes. Furthermore, the workshop showed us once more that understanding predictability and improving forecast skill on subseasonal timescales will be one of the key focuses for the coming decade, not just at ECMWF but all around the world. With our process-oriented approach in SPREADOUT to better understand European weather regimes, we are keen to help tackling this challenge!

We ended our week in Reading with an in-depth personal discussion with our collaborators at ECMWF. This was fruitful and very motivating because it once more showed their interest in our research and allowed us to further deepen our plans and specify the next steps in our collaboration.

The recordings of the talks and the posters of the workshop, as well as the working group reports can be found here. More photos of the event are provided here. / DB & CG


23/04/2019 - Highlights in research on extratropical transition

Tropical cyclones (TCs) that move into the midlatitudes undergo a chain of processes that is called “extratropical transition” (ET). Key ideas of SPREADOUT research emerged from our roots in ET research and we are still engaged in this community: In autumn, Julian was rapporteur to the Ninth World Meteorological Organization (WMO) International Workshop on TCs Sub-Topic 4.3 “Extratratropical Transition” (webpage here, report here).

In this blog post we want to highlight recent research highlights on ET in which we were involved. Most importantly, Julian and Christian substantially contributed to a two-part review paper on ET published in Monthly Weather Review (Evans et al. 2017, Keller et al. 2019). Part 2 summarises our understanding on how diabatic outflow modifies the large-scale circulation and causes forecast uncertainty during the extreme case of a TC interacting with the midlatitude jet stream (Keller et al. 2019). Our colleagues at ETH Zurich now documented systematically when and how often ET actually triggers Rossby waves (Riboldi et al. 2018a). They further studied factors that favour an amplification of the wave guide and the eventual evolution of a remote blocking anticyclone (Riboldi et al. 2018b). Such an amplified wave guide is thought to cause high-impact weather in downstream regions. However, until recently it was difficult to quantify the effect of North Atlantic TCs on European high-impact weather. Now a climatological study lead by our colleagues at University of Bern revealed for the first time the conditions under which ET can double the likelihood of extreme precipitation in Europe (Pohorsky et al. 2019 and Uni Bern press release here). Focusing more on the actual transition of the former TC, IMK-research revealed that the interaction with orography can importantly delay ET or even hinder ET (Lentik et al. 2018). More details on the latter study are in this IMK-News highlight (link here). /CG

Typhoon Choi-Wan undergoes extratropical transition near Japan and amplifies the wave guide (satellite data provided by NOAA via GridSat https://www.ncdc.noaa.gov/gridsat/, wave guide denoted as 2PVU contour from ERA-Interim).

 

References:

Evans, C., and Coauthors, 2017: The Extratropical Transition of Tropical Cyclones. Part I: Cyclone Evolution and Direct Impacts. Mon. Wea. Rev., 145, 4317–4344, doi:10.1175/MWR-D-17-0027.1.

Keller, J. H., and Coauthors, 2018: The Extratropical Transition of Tropical Cyclones. Part II: Interaction with the Midlatitude Flow, Downstream Impacts, and Implications for Predictability. Mon. Wea. Rev., 147, 1077–1106, doi:10.1175/MWR-D-17-0329.1.

Lentink, H. S., C. M. Grams, M. Riemer, and S. C. Jones, 2018: The Effects of Orography on the Extratropical Transition of Tropical Cyclones: A Case Study of Typhoon Sinlaku (2008). Mon. Wea. Rev., 146, 4231–4246, doi:10.1175/MWR-D-18-0150.1.

Pohorsky, R., M. Röthlisberger, C. M. Grams, J. Riboldi, and O. Martius, 2019: The Climatological Impact of Recurving North Atlantic Tropical Cyclones on Downstream Extreme Precipitation Events. Mon. Wea. Rev., 147, 1513–1532, doi:10.1175/MWR-D-18-0195.1.

Riboldi, J., M. Röthlisberger, and C. M. Grams, 2018a: Rossby Wave Initiation by Recurving Tropical Cyclones in the Western North Pacific. Mon. Wea. Rev., 146, 1283–1301, doi:10.1175/MWR-D-17-0219.1.

Riboldi, J., C. M. Grams, M. Riemer, and H. M. Archambault, 2018b: A Phase Locking Perspective on Rossby Wave Amplification and Atmospheric Blocking Downstream of Recurving Western North Pacific Tropical Cyclones. Mon. Wea. Rev., 147, 567–589, doi:10.1175/MWR-D-18-0271.1.

18/04/2019 - 3 Months Research Stay at Monash University in Melbourne, Australia

AGGrams_Hauser_Melbourne2
AGGrams_Hauser_Melbourne

Seraphine Hauser, Master’s student in the Large-scale dynamics and predictability group, spent the last 3 months in Australia to work on her thesis about ‘A weather system perspective on cool-season rainfall variability in southeastern Australia during El Niño’ in the School of Earth, Atmosphere and Environment in Melbourne. Together with her supervisors abroad, Michael Reeder and Shayne McGregor, she discussed her latest results and got inspiration for further investigations. Seraphine’s analysis reveals the importance of midlatitude weather systems for the month-to-month rainfall variability that is observed during El Niño. In particular, the interplay of blocking anticyclones, cut-off systems and warm conveyor belts determines whether southeastern Australia experiences anomalously dry or wet conditions – an important information for the agricultural sector. During her stay in Melbourne, which was supported by the ARC Center of Excellence for Climate System Science, Seraphine also got the chance to visit the Bureau of Meteorology to further expand her expertise on the characteristics of weather and climate in Down Under.

Regarding the last 3 months, Seraphine is very happy about the experiences and exchange with researchers at Monash University and grateful that the final thesis will feature many of Michael’s and Shayne’s suggestions. /SH


20/02/2019 - Welcome Moritz Pickl

We welcome Moritz Pickl in the group “Large-scale Dynamics and Predictability”. Moritz received a Bachelor’s degree in Freiburg and then moved to the University of Berne for a Master’s degree in Climate Sciences with specialization in Atmospheric Sciences. In his thesis he studied the variability of North Atlantic teleconnections and ocean-atmosphere interaction during the last millennium. He continued with a one-year internship at MeteoSwiss where he contributed to the preparation of the Swiss Climate Change Scenarios CH2018.

Moritz now starts a PhD in which he will investigate the sensitivity of diabatic outflow and its impact on the large-scale circulation with numerical experiments in ICON and with data from the IFS ensemble. This will be an important component of the project “SPREADOUT” and inform us if the correct representation of diabatic outflow is critical during weather regime life cycle stages. Moritz is based at Campus North (435, office 316a). We wish Moritz a great start, success and a lot of fun with his work and colleagues at IMK. Welcome! / CG


13/01/2019 - Representation of synoptic‐scale Rossby Wave Packets and Blocking in the S2S Prediction Project Database

AGGrams_Quinting_Vitart_Fig2
Fig 1. Bias in RWP (top) initiation and (bottom) decay frequency for lead time of 21–27 days. Positive (negative) values indicate an overestimation (underestimation). Taken from Fig. 2 in [1].

Equatorward and poleward wind perturbations propagating eastward along the fast flowing air currents in midlatitudes are commonly referred to as Rossby wave packets (RWPs). Typically, the waves form in the entrance region of the midlatitude storm tracks, that is, over the western North Pacific and the western North Atlantic. Regions of RWP decay are the exit regions of the storm tracks over North America and the East Atlantic/European region.

The occurrence of RWPs has been linked to extreme weather events such as intense winter storms, heat waves, and heavy precipitation. Hence, an adequate representation of RWPs in state‐of‐the‐art numerical weather prediction models is desirable to better predict these weather extremes.

In a recent study [1], we now verify for the first time the representation of RWPs in a set of 11 numerical weather prediction models on time‐scales of up to 28 days. It is shown that fundamental properties such as their climatological frequency of occurrence, their life time, and their mean propagation distance are represented reasonably well. However, models ‐ especially those with a rather coarse horizontal grid spacing ‐ struggle to adequately represent the frequency of decay of these waves in the exit region of the storm tracks over the Atlantic/European sector. Instead of decaying over the eastern North Atlantic, RWPs propagate into far eastern Europe likely due to an underestimation of the occurrence frequency of long‐lasting and stationary high pressure systems – commonly referred to as blocking highs. The observed systematic errors in the frequency of blocking highs and in the RWP decay is most pronounced but not unique to models with coarse resolution. That the observed errors are not purely resolution dependent points to the effect of the different representation of key physical processes for RWP dynamics in models of the S2S database. To pinpoint these processes with process-oriented diagnostics is one goal of the Large-scale dynamics and predictability group./JQ

[1] Quinting, J.F., and F. Vitart, Representation of synoptic‐scale Rossby Wave Packets and Blocking in the S2S Prediction Project Database, Geophys. Res. Lett., 46. https://doi.org/10.1029/2018GL081381 (2019).


17/10/2018 - Process-oriented Understanding of weather forecast error

Forecast error for 2m temperature
Fig. 1: Forecast error for 2m temperature in a six-day (+144h) forecast valid at 00 UTC, 13 March 2016. The ECMWF high resolution forecast is verified against surface observations. Taken from Fig. 1c in [1].

Despite huge progress made in numerical weather prediction, occasionally severe forecast errors occur affecting large regions. In Europe, such “forecast busts” are related to a misforecast of the large-scale circulation over the Atlantic-European region. An example on how this affects 2m temperature forecast over Europe is shown in Figure 1. In this six-day forecast issued on 07 March 2016, the model predicts too mild conditions for wide parts of western and Central Europe whereas it predicts too cold conditions in Italy and the Balkans (Figure 1; note that data from more weather stations is available in central Europe and thus the density of available surface observations is much higher there).

The March 2016 forecast bust was related to the onset of a stationary high pressure system over the North Sea region – a so-called European blocking regime. Such weather regimes typically last for several days to a few weeks and affect entire Europe. Thus, it is important to understand why numerical models struggle in correctly predicting their life cycles.

In a recently published study [1], we now reveal that condensational processes associated with the warm conveyer belt (WCB) of an extratropical cyclone effectively amplify a small error early in a weather forecast and projects it on the large-scale circulation resulting in the severe forecast bust for entire Europe for the later forecast hours.

The group now investigates if this is a singular case or if WCBs and other processes acting on weather time scales generally dilute forecast skill for the large-scale weather regimes on medium-range to subseasonal time scales (10-30 days). Therefore, we investigate dynamical processes driving weather regime life cycles using reanalysis and historical weather forecast data. This includes the investigation of how slower climate modes such as the stratosphere, the ocean state, or the Madden-Julian-Oscillation affect predictability of weather regimes [2] and how weather regimes modulate surface weather on subseasonal time scales [2, 3].

The group is funded by the Helmholtz Association with a Helmholtz Young Investigator Group Grant for the project “Subseasonal Predictability: Understanding the Role of Diabatic Outflow” (SPREADOUT). /CG.

[1] C. M. Grams, L. Magnusson, and E. Madonna, An atmospheric dynamics‘ perspective on the amplification and propagation of forecast error in numerical weather prediction models: a case study. Quarterly Journal of the Royal Meteorological Society, in press, doi:10.1002/qj.3353 (2018).

[2] C. M. Grams, R. Beerli, S. Pfenninger, I. Staffell, H. Wernli, Balancing Europe’s wind-power output through spatial deployment informed by weather regimes. Nature Climate Change. 7, 557–562, doi:10.1038/NCLIMATE3338 (2017).

[3] L. Papritz, C. M. Grams, Linking Low‐Frequency Large‐Scale Circulation Patterns to Cold Air Outbreak Formation in the Northeastern North Atlantic. Geophysical Research Letters. 45, 2542–2553, doi:10.1002/2017GL076921 (2018).


12/10/2018 - Spreadout at the WWRP/WCRP S2S and S2D conference in Boulder, CO

AGGrams_S2S_collage
Impressions from the S2S conference in Boulder. Photo credits: University Corporation for Atmospheric Science

The conference aimed to foster the exchange of information between the S2S and S2D communities, to identify challenges for transferring S2S and S2D research into operations, and to identify new collaborations, initiatives and urgent science issues (https://www.wcrp-climate.org/s2s-s2d-2018-home). Our contributions covered various of the conference themes: Dominik presented his applied research with Remo Beerli on the importance of the wintertime stratospheric polar vortex in serving as a predictor of month-ahead wind electricity generation in Europe. Julian’s and Christian’s contributions focused on current science issues. Christian pointed out that diabatic processes within rapidly ascending midlatitude airstreams (warm conveyor belts - WCBs) contribute to the formation and maintenance of blocked weather regimes. Julian then stressed in one of his contributions that subseasonal numerical weather prediction models generally underestimate the occurrence of stationary anticyclones (blocking) over the Atlantic-European region. This may be due to an inadequate representation of diabatic processes – a hypothesis which we now study in further detail. Our research combining process understanding and applications received quite positive feedback. Motivated by fruitful and very inspiring discussions with the S2S community, we now continue to identify processes acting on weather time scales that might dilute forecast skill on subseasonal time scales. /JQ.


18/07/2018 - Welcome Jan Wandel

AGGrams_Groupphoto
The research group "Large-scale Dynamics and Predictability": Christian Grams, Jan Wandel, Dominik Büeler, Nadine Schittko, Seraphine Hauser, and Julian Quinting.

We are very happy to welcome Jan Wandel as a student assistant in our group. Jan got a Bachelor’s and Master’s degree in Meteorology from KIT. During his studies he was engaged in IMK’s “early weather hazards warning” (Wettergefahrenfrühwarnung). In his Masterthesis at IMK-TRO Jan studied the synoptic environment triggering hailstorms in Europe.

Jan will now take care of operational weather regime forecast products in our group and investigate the linkage of weather regimes and hailstorms in collaboration with his former group. Jan will also develop operational forecast products for weather regimes on sub-seasonal time-scales. We wish Jan a great start, success and a lot of fun with his work and colleagues at IMK. Welcome!


Verbessern von Wettervorhersagen auf sub-saisonalen Zeitskalen

IR-Sat+Jet
Abb. 1: Meteorologische Situation während der Hitzewelle in Mitteleuropa im Juli 2015: Infrarot Satellitenbild, blockierendes Hochdruckgebiet (blaue Schattierung), Ablenkung des Strahlstroms (grüne Kontur), „warm conveyor belt“ (blau-rote Trajektorien).

Fortschritte in der numerischen Wettervorhersage ermöglichen immer langfristigere Vorhersagen auf sogenannten sub-saisonalen Zeitskalen von einigen Tagen bis Wochen im Voraus. Auf diesen Zeitskalen bestimmen beständige, quasi-ortsfeste, und wiederkehrende Wetterregime die Variabilität der großräumigen Strömung. Diese Wetterregime bestimmen den Charakter des täglichen Wetters für eine längere Zeitperiode und für Gebiete der Größe Europas. Daher beeinflussen Wetterregime zahlreiche gesellschaftliche und wirtschaftliche Aktivitäten, wie z.B. die Landwirtschaft, den Verkehr oder die erneuerbaren Energien [1].

Dennoch ist es weiter eine große Herausforderung den Lebenszyklus dieser Wetterregime auf sub-saisonalen Zeitskalen korrekt vorherzusagen. Grund dafür ist das gleichzeitige Wirken meteorologischer Prozesse auf sehr verschiedenen räumlichen und zeitlichen Skalen: Auf kürzeren Zeitskalen, werden Wetterregimelebenszyklen von Wettersystemen, wie etwa außertropischen Tiefdruckgebieten oder Gewittersystemen beeinflusst. Auf längeren Zeitskalen sind langsamere Elemente des Klimasystems, wie zum Beispiel die Stratosphäre oder tropische Konvektion (Madden-Julian-Oszillation), Einflussfaktoren für Wetterregime, die teilweise Vorhersagbarkeit für Wetterregime auf sub-saisonalen Zeitskalen geben.

Die neu am IMK-TRO eingerichtete Gruppe „Großräumige Dynamik und Vorhersagbarkeit“ erforscht die physikalischen und dynamischen Prozesse, die Vorhersagbarkeit und Vorhersagegüte auf sub-saisonalen Zeitskalen bestimmen. Dabei legt sie den Schwerpunkt auf den Lebenszyklus großskaliger Wetterregime im Atlantisch-Europäischen Raum. Darüber hinaus erforscht die Gruppe in Zusammenarbeit mit Wetterdiensten neue probabilistische Vorhersageprodukte für die sub-saisonale Zeitskala.

Im Folgenden wird ein erstes Vorhersageprodukt am Beispiel der frühen Hitzewelle in Mitteleuropa, die vom 19.-22. April ihren Höhepunkt erreichte, gezeigt (Abbildung 2). Die Übersichtsdarstellung zeigt zunächst wie wahrscheinlich ein spezifisches Wetterregime in den nächsten 15 Tagen auftritt (Abbildung 2a). Mehr Details liefert eine Darstellung, die anzeigt wie stark verschiedene Regime in einer probabilistischen Vorhersage ausgeprägt sind (Abbildung 2b). Im Fall der Hitzewelle im April 2018 zeigten diese Vorhersageprodukte korrekterweise den Übergang eines “Skandinavischen Hochs“ (ScBL) in ein „Zonales Regime“, und damit das Ende der Hitzewelle, bereits mehr als eine Woche im Voraus an (vgl. Abbildung 2c und 2b). Oft sind jedoch gerade solche Regimeübergänge mit heutigen Wettervorhersagesystemen überhaupt nicht gut vorhersagbar.

Die Gruppe untersucht nun im Detail wie gut sub-saisonale Wettervorhersagesysteme die Lebenszyklen von Wetterregimen darstellen. Insbesondere werden physikalische Prozesse auf kürzeren Zeitskalen,  sowie deren Veränderung durch langsamere Komponenten des Klimasystems wie der Madden-Julian-Oszillation oder der Stratosphäre [2] untersucht. Diese Grundlagenforschung an der Schnittstelle verschiedener räumlicher und zeitlicher Skalen, wird nicht nur das Verständnis von Wetterregimen verbessern, sondern auch zum übergeordneten Ziel von universellen Vorhersagesystemen für Wetter und Klima beitragen.

Die Helmholtz Gemeinschaft fördert diese Forschungstätigkeit als Helmholtz Nachwuchsgruppe “Sub-seasonal Predictability: Understanding the Role of Diabatic Outflow” (SPREADOUT).

Link: Gruppe „Großräumige Dynamik und Vorhersagbarkeit“ http://www.imk-tro.kit.edu/7425.php

[1] C. M. Grams, R. Beerli, S. Pfenninger, I. Staffell, H. Wernli, Balancing Europe’s wind-power output through spatial deployment informed by weather regimes. Nature Climate Change. 7, 557–562, doi:10.1038/NCLIMATE3338 (2017).

[2] Papritz L., Grams C. M., Linking Low‐Frequency Large‐Scale Circulation Patterns to Cold Air Outbreak Formation in the Northeastern North Atlantic. Geophysical Research Letters. 45, 2542–2553, doi:10.1002/2017GL076921 (2018).

Abb. 2: Beispiele für neuartige Wetterregime Vorhersageprodukte: (a) Ensemble Vorhersage von 12UTC 15. April 2018. Die Balken zeigen die relative Wahrscheinlichkeit eines von 7 verschiedenen Wetterregimen an. Die unteren Zeilen zeigen jeweils an, welches Regime das Ensemble-Mittel, die Kontroll- und die hochaufgelöste Vorhersage vorhersagen (letztere nur bis 10 Tage im Voraus). (b) Ensemble-Verteilung der jeweiligen Ausprägung eines der 7 Wetterregime. Blasse Farben zeigen die jeweils stärkste und schwächste Ausprägung an, dunklere Farben das 25. und 75. Perzentil. Linien zeigen die Ausprägung in der Kontrollvorhersage (dick durchgezogen), hochaufgelösten Vorhersage (dick strichliert, nur bis 10 Tage), und im Ensemble-Mittels (dünn strichliert) an. (c) Tatsächlich aufgetretene Ausprägung der 7 Wetterregime vom 7. April bis 7. Mai 2018.

11/06/2018 - Visit of AXPO Trading

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Julian Quinting, Dominik Büeler, energy meteorologist Remo Beerli, and Christian Grams in front of the AXPO main building in Baden (Switzerland).

The SPREADOUT group visited AXPO Trading in Baden (Switzerland) on 11 June 2018. The main purpose of the visit was to inform energy traders and meteorologists at AXPO about current research activities and to discuss forecast tools useful to the energy sector. After an introductory presentation on SPREADOUT by Christian Grams and Dominik Büeler, Remo Beerli (energy meteorologist at AXPO) showed us the trading floor. There we gained interesting insights in the day-to-day business of energy meteorologists and learned about the forecast products that are needed to provide reliable information to the energy traders. Future collaborations and research avenues were elaborated in a lively discussion in the afternoon.


01/06/2018 - Welcome Nadine Schittko and Seraphine Hauser

Spreadout
Dominik Büeler, Nadine Schittko, Seraphine Hauser, Christian Grams, Julian Quinting

SPREADOUT is growing further: We welcome Nadine Schittko and Seraphine Hauser who will join the group for the next year to complete their Master’s degree.

Nadine will analyse the representation of tropical cyclones in the global forecast model ICON. In the framework of the Master’s thesis, she will implement different tropical cyclone tracking algorithms to verify the intensity and motion of tropical cyclones against best track data. Some impact relevant North Atlantic Hurriances in 2016/17 will be studied in greater detail. The project is executed in close collaboration with DWD where the resulting tools may be used operationally in the future for verification purposes.

In her Master’s thesis, Seraphine is going to analyse “The effect of the El Nino Southern Oscillation on Australian climate variability from a weather system perspective”. Using a novel data set of objectively identified weather systems, the goal of the first part of the project is to develop a conceptual picture on how different states of the El Nino Southern Oscillation are related to the occurrence frequency of subtropical and midlatitude weather systems. The results will then be used to attribute the observed variability in temperature and precipitation to these weather systems.

We wish Nadine and Seraphine great success and a lot of fun with their work!


01/03/2018 - Welcome

We welcome Dominik Büeler as a new member of the group “Large-scale Dynamics and Predictability”. Dominik received his PhD from ETH Zurich for his thesis entitled "Potential vorticity diagnostics to quantify effects of latent heating in extratropical cyclones: methodology and application to idealized climate change simulations". Already before his PhD, Dominik gained experience both in climate and weather modelling: he analysed marine boundary layer clouds in ECHAM5-HAM and investigated the northern mid- and high-latitude climate in a climate change mitigation scenario in his Bachelor and Master thesis, respectively. During a one-year internship at MeteoSwiss, he worked on the potential of COSMO in predicting photovoltaic power, which offered him an insight into applied weather science. After a short PostDoc project at ETH Zurich last autumn on month-ahead predictability of European wind power, Dominik will continue research in the field of sub-seasonal predictability at KIT in the project “SPREADOUT”. He will study the representation of large-scale weather regimes in sub-seasonal numerical weather prediction models and physical processes governing weather regime life cycles. We wish Dominik a great start, success and a lot of fun with his work and colleagues at IMK.

 

15/02/2018 - Welcome

We welcome Julian Quinting as a senior scientist in the group “Large-scale Dynamics and Predictability”. Julian received his PhD from KIT for his thesis entitled “ The impact of tropical convection on the dynamics and predictability of midlatitude Rossby waves: a climatological study” His Diploma and PhD research was part of the PANDOWAE research unit. After his PostDoc time at ETH Zurich and Monash University, Melbourne, Julian is back at KIT and will work on Sub-seasonal predictability in the project “SPREADOUT”.

As a PostDoc in Zurich, Julian worked on upper-level frontogenesis, Rossby wave dynamics, and MJO teleconnections. In addition, he helped preparing the NAWDEX field campaign and in autumn 2016 contributed actively to flight planning and forecasting based in Iceland. His research focus during the last 2 years at Monash shifted to the understanding of physical processes driving extreme events in the Australian region (e.g. heat waves) and southern hemispheric Rossby wave dynamics. In SPREADOUT Julian will study the representation of physical processes in global NWP data sets, their modulation by global teleconnections (e.g. MJO, ENSO), and how they affect sub-seasonal predictability for Europe. We wish Julian great success and a lot of fun with his work and colleagues at IMK.

 

 

12/12/2017 - Statement regarding Nature Geoscience manuscript “Southward shift of the global wind energy resource under high carbon dioxide emissions”

Foto: Bernhard Mühr, www.wolkenatlas.de

Based on an ensemble of 10 global climate model simulations following the RCP4.5 and RCP8.5 scenarios, this study reports a strong decrease of potential wind electricity generation in the mid-latitudes during the XXI Century (https://www.nature.com/articles/s41561-017-0029-9). The authors use a simple methodology and data with low spatio-temporal resolution, and consider an exemplary wind energy turbine for the computations. Compared to other regions of the world (notably North America), the changes for Europe are comparatively small. These projections for Europe are partially in agreement with studies based on datasets with much higher spatial and temporal resolution (e.g., Tobin et al., 2015, Reyers et al., 2016, Moemken et al., 2018). These studies reveal rather small changes of wind energy potentials for Europe on the continental scale (+/- 5%). On the other hand, they point to increased variability of wind electricity generation in multiple time scales. The differences to the Nature Geoscience study are related with the different data resolution and methodology.

In particular, an increased occurrence of low wind speed (< 3m/s) events reported in Moemken et al. (2018) may cause challenges for the energy supply across Europe. However, this challenge can be overcome with suitable mitigation strategies and updated planning. For example, Grams et al. (2017) provide evidence that the concentration of wind parks in some areas (e.g. North Sea) is problematic to warrant a reliable wind electricity generation. A pan-European management strategy and a more de-central distribution of wind parks would permit to balance the weather and climate variability and thus contribute to a more reliable energy supply. Moreover, the joint management of different renewable sources (notably solar) would further contribute to mitigate the possible changes in wind energy production in future decades.

 

References:

Grams, C. M., R. Beerli, S. Pfenninger, I. Staffell, and H. Wernli, 2017: Balancing Europe’s wind-power output through spatial deployment informed by weather regimes. Nature Climate Change, 7, 557–562, doi:10.1038/nclimate3338.

Moemken, J., M. Reyers, H. Feldmann, and J. G. Pinto, 2018: Wind speed and wind energy potentials in EURO-CORDEX ensemble simulations: evaluation and future changes, Journal of Geophysical Research: Atmospheres, in revision.

Reyers, M., J. Moemken, and J. G. Pinto, 2016: Future changes of wind energy potentials over Europe in a large CMIP5 multi-model ensemble. Int. J. Climatol., 36, 783–796, doi:10.1002/joc.4382.

Tobin, I., and Coauthors, 2015: Assessing climate change impacts on European wind energy from ENSEMBLES high-resolution climate projections. Climatic Change, 128, 99–112, doi:10.1007/s10584-014-1291-0.

Link: http://www.sek.kit.edu/kit_express_3874.php

Contact: Joaquim G. Pinto http://www.imk-tro.kit.edu/14_7131.php

Contact: Christian M. Grams http://www.imk-tro.kit.edu/14_7356.php