Article
Geosciences, Multidisciplinary
F. Ragone, F. Bouchet
Summary: The lack of statistics in climate models hinders the analysis of extreme events, as direct sampling is not feasible due to computational costs. By using rare event algorithms, we can improve the statistics of extreme events in state-of-the-art climate models. Our study on extreme warm summers and heatwaves over France and Scandinavia shows that extreme warm summers are associated with specific hemispheric teleconnection patterns, with the most extreme summers linked to rare subseasonal heatwaves.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Meteorology & Atmospheric Sciences
Jhan-Carlo Espinoza, Paola A. Arias, Vincent Moron, Clementine Junquas, Hans Segura, Juan Pablo Sierra-Perez, Sly Wongchuig, Thomas Condom
Summary: Through analyzing the atmospheric variations over tropical South America, nine atmospheric circulation patterns are identified, showing significant long-term changes and impacts on the regional climate. The patterns help explain the stages of low-level circulation throughout the year and their effects on the South American monsoon onset and dry conditions.
JOURNAL OF CLIMATE
(2021)
Article
Meteorology & Atmospheric Sciences
Yingxia Gao, Pang-Chi Hsu, Shaojing Che, Changwen Yu, Shiru Han
Summary: We investigated the characteristics and mechanisms of subseasonal precipitation variability in North China during the rainy season. Two dominant intraseasonal modes with periods of 8-20 and 30-60 days were identified, explaining 62.8% of the total precipitation variability. Most heavy rainfall events were observed with enhanced positive phases of biweekly or/and 30-60-day precipitation modes. The anomalous lower-level southerly perturbations and summer-mean thermal wind were found to be key factors causing these precipitation anomalies.
JOURNAL OF CLIMATE
(2022)
Article
Environmental Sciences
Ruping Mo, Hai Lin, Frederic Vitart
Summary: Based on analyses of observation-based data and numerical weather prediction model output, this study reveals that a warm-season atmospheric river moved from Southeast Asia across the North Pacific in June 2021, contributing heat and moisture to a heatwave event in western North America. The movement of this system resulted in substantial spillover of moisture and sensible heat, forming a positive feedback mechanism that potentially led to the expansion of the heatwave event.
COMMUNICATIONS EARTH & ENVIRONMENT
(2022)
Article
Meteorology & Atmospheric Sciences
Hai Lin, Bin Yu, Nicholas M. J. Hall
Summary: This study reveals that the warm Arctic-cold North American pattern can be generated solely by atmospheric internal dynamics, which has significant implications for our understanding of the impact of global warming.
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2022)
Article
Meteorology & Atmospheric Sciences
Nedjeljka Zagar, Frank Lunkeit, Frank Sielmann, Wenlin Xiao
Summary: The wavenumber filtering of Kelvin waves is performed by analyzing the ERAS data through multivariate projection. The results show that the zonal wavenumber spectra of Kelvin waves exhibit continuous and red behavior, with rotational kinetic energy dominating over divergent kinetic energy at zonal wavenumber k = 1. The strongest variability is found in periods of 8-12 days in the troposphere.
JOURNAL OF CLIMATE
(2022)
Article
Oceanography
Rodrigue Anicet Imbol Koungue, Peter Brandt
Summary: The study investigates the intraseasonal variability of the tropical eastern boundary upwelling region in the Atlantic Ocean using multiyear mooring and satellite data. Pronounced oscillations of alongshore velocity and sea level at periods of about 90 and 120 days were observed, with equatorial forcing via equatorial and coastally trapped waves. Variability is enhanced by local zonal wind fluctuations and linked to a second equatorial basin mode, with additional forcing likely originating in the central and western tropical North Atlantic.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Meteorology & Atmospheric Sciences
Xudong Wang, Renhe Zhang, Dachao Jin, Yu Zhang
Summary: A strong coherence of the summer surface air temperature anomalies exists over eastern Eurasia and central Eurasia, which is closely related to a remarkable intraseasonal variability. The intraseasonal temperature variation is influenced by the upper tropospheric wave train and is characterized by a seesaw pattern between eastern Eurasia and central Eurasia. The horizontal and vertical advection, as well as the anomalous vertical motion and diabatic heating, play important roles in perturbing the temperature anomalies. The propagation of the Rossby wave train helps to maintain the circulation anomalies associated with the temperature seesaw.
JOURNAL OF CLIMATE
(2023)
Article
Oceanography
Lina Song, Fan Wang, Yuanlong Li, June-Yi Lee
Summary: The Indian summer monsoon intraseasonal oscillation is a significant mode of tropical atmospheric intraseasonal variability, particularly affecting the zonal currents in the Indo-Pacific warm pool region. This study confirms a close association between the intraseasonal variability of zonal currents and the monsoon oscillation. The variability is primarily driven by the wind pressure associated with the oscillation, leading to significant changes in the intensity and spatial distribution of zonal currents in the region.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Oceanography
Zhixiang Zhang, Jianing Wang, Fan Wang, Qiang Ma
Summary: This study observed strong multi-timescale variabilities of subsurface zonal velocity beneath the North Equatorial Countercurrent (NECC). The observed velocity showed peaks at intraseasonal, semiannual, and annual periods, and was interconnected with the El Nino-Southern Oscillation (ENSO) cycle. The study also revealed the mechanisms behind these variabilities, with long Rossby waves responsible for the semiannual and annual cycles, and short Rossby waves inducing the intraseasonal variability.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Meteorology & Atmospheric Sciences
Yanbo Nie, Jianqi Sun
Summary: This study explores the mechanisms behind low-latitude intraseasonal oscillations and their impact on regional persistent extreme precipitation events in Southwest China during rainy seasons. The majority of these events are characterized by 7-20-day variability, which is preconditioned by two different types of 7-20-day Rossby waves over the western North Pacific. These waves have direct and indirect effects on type-1 and type-2 events, respectively.
JOURNAL OF CLIMATE
(2023)
Article
Meteorology & Atmospheric Sciences
Zijie Zhao, Xihan Zhang
Summary: Bimodal precipitation is a globally observed event with a significant impact on agriculture, public health, and insurance needs. Research on the detection and quantification of this event is limited, but comparing different methods may provide appropriate criteria for method choice in various study types.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2021)
Article
Meteorology & Atmospheric Sciences
Lina Boljka, David W. J. Thompson, Ying Li
Summary: Baroclinic waves drive regional weather variations and extratropical general circulation variability, forming coherent wave packets that propagate eastward through downstream development. Downstream suppression of baroclinic activity occurs in the wake of eastward propagating disturbances, playing a significant role in driving subseasonal periodicity in both hemispheres.
JOURNAL OF CLIMATE
(2021)
Article
Oceanography
Qingyang Song, Hidenori Aiki
Summary: This study investigates energy transfer and interaction of wind-driven intraseasonal waves in the tropical Atlantic Ocean, revealing dominant influence of Kelvin waves in the 80-day scenario and Yanai waves in the 30-day scenario, with comparable magnitudes in the 50-day scenario. The research also identifies asymmetric distribution of wave energy in the central basin and coastally trapped Kelvin waves along the African coast.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2021)
Article
Environmental Sciences
Tengfei Xu, Zexun Wei, Shujiang Li, Raden Dwi Susanto, Nyoman Radiarta, Chao Yuan, Agus Setiawan, Anastasia Kuswardani, Teguh Agustiadi, Mukti Trenggono
Summary: The high sea surface chlorophyll-a concentration along the southern coast of Java is primarily influenced by monsoon-driven upwelling and rainfall in the Indian Ocean and Indonesian seas sides. Local Ekman pumping plays a secondary role, while ocean rainfall input has little effect.
Article
Meteorology & Atmospheric Sciences
J. J. Gomez-Navarro, C. C. Raible, J. A. Garcia-Valero, M. Messmer, J. P. Montavez, O. Martius
Summary: This study presents a new strategy for constraining extreme precipitation events based on a combination of statistical and dynamical downscaling. The results show that this strategy is suitable for precipitation extremes in the upper Aare catchment, Switzerland, although there are some limitations in identifying extreme events in summer and underestimating the sensitivity of extreme events to climate change.
Article
Geosciences, Multidisciplinary
Veronika Valler, Jorg Franke, Yuri Brugnara, Stefan Bronnimann
Summary: Data assimilation techniques are increasingly popular for climate reconstruction, estimating past climate states from observation information and model simulations. The improved version EKF400v2 shows enhanced reconstruction skill compared to version 1, especially in variables like precipitation and sea-level pressure, with the addition of new observation types.
GEOSCIENCE DATA JOURNAL
(2022)
Article
Multidisciplinary Sciences
Lukas Reichen, Angela-Maria Burgdorf, Stefan Bronnimann, Jorg Franke, Ralf Hand, Veronika Valler, Eric Samakinwa, Yuri Brugnara, This Rutishauser
Summary: A reconstruction of the cold season climate in the northern midlatitudes based on freezing and thawing dates of rivers reveals a cold spell that affected Eurasia from 1808/9 to 1815/6. Alongside two volcanic eruptions, increased snow cover played a significant role in this phenomenon. The study presents temperature field reconstructions for the northern midlatitudes from 1701-1905 using extensive phenological data. The findings show that northern midlatitude land temperatures have exceeded the variability range of the 18th and 19th centuries, with recent warming contributing an additional 1.5 degrees Celsius.
NATURE COMMUNICATIONS
(2022)
Article
Meteorology & Atmospheric Sciences
Luciano G. Andrian, Marisol Osman, Carolina S. Vera
Summary: This paper evaluates the predictability and skill of the models from the NMME project in South America, and finds that temperature predictability is higher than precipitation predictability. The multi-model ensemble signal dominates temperature variance in autumn and summer, while inter-model biases dominate in spring and winter. The highest predictability of precipitation is found in tropical latitudes.
Article
Green & Sustainable Science & Technology
Noelia Otero, Olivia Martius, Sam Allen, Hannah Bloomfield, Bettina Schaefli
Summary: Meeting carbon-reduction targets requires consideration of climate variability and change on climate-sensitive renewable energy sources. A study on energy droughts, periods of low energy production or high residual load, found variations in duration and severity across countries and seasons. Sharing renewable energy sources during prolonged periods of low production and high demand is highlighted as important.
Article
Meteorology & Atmospheric Sciences
Jerome Kopp, Katharina Schroeer, Cornelia Schwierz, Alessandro Hering, Urs Germann, Olivia Martiusl
Article
Meteorology & Atmospheric Sciences
Sam Allen, Jonas Bhend, Olivia Martius, Johanna Ziegel
Summary: To mitigate the impacts of adverse weather, meteorological services issue weather warnings based on forecasts from prediction systems. Evaluating forecasts for high-impact weather is challenging due to the complexity of compound weather events. This paper discusses weighted verification tools to evaluate probabilistic forecasts for specific outcomes such as extreme heat events.
WEATHER AND FORECASTING
(2023)
Article
Meteorology & Atmospheric Sciences
Pauline Rivoire, Philomene Le Gall, Anne-Catherine Favre, Philippe Naveau, Olivia Martius
Summary: This article introduces the method of using regional frequency analysis to estimate the daily rainfall return levels of ERA-5 reanalysis product on the European continent associated with large return periods. By inferring return level estimates through clustering algorithms, relatively parsimonious models can also compete well against more complex statistical models.
WEATHER AND CLIMATE EXTREMES
(2022)
Article
Multidisciplinary Sciences
Bart J. J. M. van den Hurk, Christopher J. White, Alexandre M. Ramos, Philip J. Ward, Olivia Martius, Indiana Olbert, Kathryn Roscoe, Henrique M. D. Goulart, Jakob Zscheischler
Summary: Consideration of compound drivers, hazards, and impacts is often overlooked in the Disaster Risk Reduction (DRR) cycle, leading to limited understanding of risk and actions. This article provides examples of how compound thinking can affect different areas of disaster risk management and emphasizes the need for practical guidelines. The authors identify five DRR categories and present studies that highlight the role of considering compound factors in early warning, emergency response, infrastructure management, long-term planning, and capacity building.
Article
Environmental Sciences
Noelia Otero, Pascal Horton, Olivia Martius, Sam Allen, Massimiliano Zappa, Tobias Weschler, Bettina Schaefli
Summary: Hydropower is an important renewable energy source that can complement solar and wind power in achieving a low-carbon power system. However, its production is dependent on local weather conditions and climate variability. A study in Switzerland, where hydropower provides the largest share of electricity production, found that the impacts of hot-dry conditions on hydropower are case-specific.
ENVIRONMENTAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Alessio Ciullo, Eric Strobl, Simona Meiler, Olivia Martius, David N. Bresch
Summary: This study finds that global pooling generally provides greater financial resilience and risk diversification compared to regional pooling in sovereign catastrophe risk pools. Extreme weather events can severely impact national economies, leading to reliance on slow and uncertain foreign financial aid. The study introduces a method for maximizing risk diversification and finds that global pooling always provides higher risk diversification and benefits more countries.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Angela-Maria Burgdorf, Stefan Broennimann, George Adamson, Tatsuya Amano, Yasuyuki Aono, David Barriopedro, Teresa Bullon, Chantal Camenisch, Dario Camuffo, Valeerie Daux, Maria del Rosario Prieto, Petr Dobrovolny, David Gallego, Ricardo Garcia-Herrera, Joelle Gergis, Stefan Grab, Matthew J. Hannaford, Jari Holopainen, Clare Kelso, Zoltan Kern, Andrea Kiss, Elaine Kuan-Hui Lin, Neil J. Loader, Martin Mozny, David Nash, Sharon E. Nicholson, Christian Pfister, Fernando S. Rodrigo, This Rutishauser, Sapna Sharma, Katalin Takacs, Ernesto T. Vargas, Inmaculada Vega
Summary: Documentary climate data, derived from written historical documents, provide evidence of past climate. A global dataset of documentary climate time series has not been compiled before. This study presents the first global collection of documentary climate records, consisting of 621 time series, including temperature, precipitation, and wind regime variations. The results show strong correlations, particularly for temperature-sensitive series, indicating the considerable potential of documentary records as climate data.
Article
Meteorology & Atmospheric Sciences
Jerome Kopp, Agostino Manzato, Alessandro Hering, Urs Germann, Olivia Martius
Summary: We present the first study of hailstorms using a network of 80 automatic hail sensors from Switzerland. The sensors provide live recording of hailstone kinetic energy and precise timing of impacts. By comparing the sensor observations with hailpad observations, we find that both devices measure the same hail size distributions. Using the timing information, we measure the local duration of hail events, the cumulative time distribution of impacts, and the time of the largest hailstone.
ATMOSPHERIC MEASUREMENT TECHNIQUES
(2023)
Article
Environmental Sciences
Stefan Broennimann
Summary: The recovery of the ozone layer over the past 25 years is difficult to detect, but there are indications of changes in stratospheric circulation. Chemical recovery is counteracted by dynamical effects.
COMMUNICATIONS EARTH & ENVIRONMENT
(2022)
Article
Geosciences, Multidisciplinary
Stefan Broennimann, Peter Stucki, Joerg Franke, Veronika Valler, Yuri Brugnara, Ralf Hand, Laura C. Slivinski, Gilbert P. Compo, Prashant D. Sardeshmukh, Michel Lang, Bettina Schaefli
Summary: European flood frequency and intensity have changed on a multidecadal scale. Floods were more frequent in the 19th and early 20th century, less frequent in the mid-20th century, and more frequent again since the 1970s. The causes of this variability are not well understood, and the connection to climate change remains unclear.
CLIMATE OF THE PAST
(2022)