Meldungsarchiv

  • Januar 2024:

    neue Veröffentlichung:

    Kanngießer, F., & Fiedler, S. (2024). “Seeing” beneath the clouds—Machine-learning-based reconstruction of North African dust plumes. AGU Advances, 5, e2023AV001042. https://doi.org/10.1029/2023AV001042

    Abstract: Mineral dust is one of the most abundant atmospheric aerosol species and has various far-reaching effects on the climate system and adverse impacts on air quality. Satellite observations can provide spatio-temporal information on dust emission and transport pathways. However, satellite observations of dust plumes are frequently obscured by clouds. We use a method based on established, machine-learning-based image in-painting techniques to restore the spatial extent of dust plumes for the first time. We train an artificial neural net (ANN) on modern reanalysis data paired with satellite-derived cloud masks. The trained ANN is applied to cloud-masked, gray-scaled images, which were derived from false color images indicating elevated dust plumes in bright magenta. The images were obtained from the Spinning Enhanced Visible and Infrared Imager instrument onboard the Meteosat Second Generation satellite. We find up to 15% of summertime observations in West Africa and 10% of summertime observations in Nubia by satellite images miss dust plumes due to cloud cover. We use the new dust-plume data to demonstrate a novel approach for validating spatial patterns of the operational forecasts provided by the World Meteorological Organization Dust Regional Center in Barcelona. The comparison elucidates often similar dust plume patterns in the forecasts and the satellite-based reconstruction, but once trained, the reconstruction is computationally inexpensive. Our proposed reconstruction provides a new opportunity for validating dust aerosol transport in numerical weather models and Earth system models. It can be adapted to other aerosol species and trace gases.

  • Dezember 2023:
    Mündliche Prüfung der Doktorarbeit von Julian Krüger

    Summary :
    The European continent experienced a considerably increased number of heat events within the last two decades, most likely driven by a surface warming due to anthropogenic greenhouse gas emissions. The investigation of heat events and associated drivers is essential due to numerous impacts, e.g., on human health. The European heat event in 2015 was accompanied by unusually cold sea surface temperatures (SSTs) south of Greenland, which led to the influence of North Atlantic SSTs being considered along with other potential drivers. This thesis incorporates three different research chapters, all contributing to disentangle the role of North Atlantic SSTs for European heat events.

    The first chapter is based on a composite study with reanalysis data and highlights that events of unusually cold North Atlantic SSTs with a negative tendency precede a surface temperature maximum over central Europe a few days later, increasing the probability for European heat events. 

    The second chapter utilises seven coupled climate models with different horizontal resolutions in the atmosphere and ocean model component. The model simulations generally confirm the identified relationship between cold North Atlantic SSTs with a negative tendency and European heat events. The relationship is better reproduced with an increased horizontal resolution, particularly of the ocean model component. 

    The third research chapter demonstrates the importance of SSTs and warm conveyor belt activity in the North Atlantic sector for the development of the 2015 European heat event. Additionally, subseasonal-to-seasonal reforecasts are used to estimate the forecast skill of North Atlantic warm conveyor belt activity and the 2015 European heat event. 

    All three research chapters emphasise to account for North Atlantic SSTs in future assessments of the European summer climate and the development of European heat events. 

  • November 2023:
    neue Veröffentlichung:

    Krüger, J, Kjellsson, J, Kedzierski, RP and Claus, M. 2023. Connecting North Atlantic SST Variability to European Heat Events over the Past Decades. Tellus A: Dynamic Meteorology and Oceanography, 75(1): 358–374. DOI: https://doi.org/10.16993/tellusa.3235

    Summary: "The intensity and frequency of European heat events has increased in the recent two decades, which has strengthened the interest about identifying potential driving mechanisms. This study investigates five different composites of North Atlantic sea surface temperatures. We find that events with an atmospherically-driven fall of cold North Atlantic sea surface temperatures are accompanied by a subsequent surface air temperature maximum over central Europe, indicating a higher probability for heat events. In addition to the surface temperature contrast, we identify a distinct atmospheric trough-ridge pattern in the North Atlantic-European sector. An additional composite of European heat events supports this time-lagged relationship between cold North Atlantic SSTs with a negative tendency and European heat events. "

  • Oktober 2023:
    neue Veröffentlichung:

    Duteil, O., Park, W. Future changes in atmospheric synoptic variability slow down ocean circulation and decrease primary productivity in the tropical Pacific Ocean. npj Clim Atmos Sci 6, 136 (2023). https://doi.org/10.1038/s41612-023-00459-3

    Summary: "This study investigates the impact of future changes in atmospheric synoptic variability (ASV) on ocean properties and biogeochemical cycles in the tropical Pacific Ocean using coupled and forced atmosphere–ocean model experiments. Future climate projections show an annual mean decrease in ASV in subtropical gyres and an increase in the tropical band. Maintaining ASV to current values lead to a deepening of the mixed layer in subtropical regions and a shalllowing at the equator associated with a sea surface temperature decrease. The changes in ASV impact the large-scale ocean circulation and the strength of the subtropical and tropical cells, which constrain the equatorial water upwelling and the tropical net primary productivity. Ultimately, this study highlights the significance of ASV in understanding the impacts of climate change on ocean dynamics and biogeochemical processes, as half of the primary productivity decline due to climate change is caused by changes of ASV in the tropical Pacific Ocean."

  • September 2023:
    neue Veröffentlichung:

    Richardson, K., Steffen, W., Lucht, W., Bendtsen, J., Cornell, S. E., Donges, J. F., Drüke, M., Fetzer, I., Bala, G., von Bloh, W., Feulner, G., Fiedler, S. , Gerten, D., Gleeson, T., Hofmann, M., Huiskamp, W., Kummu, M., Mohan, C., Nogués-Bravo, D., Petri, S., Porkka, M., Rahmstorf, S., Schaphoff, S., Thonicke, K., Tobian, A., Virkki, V., Wang-Erlandsson, L., Weber, L. and Rockström, J.  (2023) Earth beyond six of nine planetary boundaries. Sci. Adv., 9 (37), https://doi.org/10.1126/sciadv.adh2458

    Summary from https://www.stockholmresilience.org: "The planetary boundaries concept presents a set of nine planetary boundaries within which humanity can continue to develop and thrive for generations to come. In September 2023, a team of scientists quantified, for the first time, all nine processes that regulate the stability and resilience of the Earth system." [more...]

  • August 2023:
    neue Veröffentlichung:
  • Fiedler, S.,  van Noije, T., Smith, C.J.,  Boucher, O., Dufresne, J., Kirkevåg, A.,  Olivié, D., Pinto, R., Reerink, T.,  Sima, A.,  Schulz, M. (2023) Historical Changes and Reasons for Model Differences in Anthropogenic Aerosol Forcing in CMIP6. Geophysical Research Letters, 50 (15), e2023GL104848. doi.org/10.1029/2023GL104848

    Summary from https://agupubs.onlinelibrary.wiley.com/: "Aerosols are particles in the atmosphere with sizes ranging from nanometers to tens of micrometers, which are emitted by natural and anthropogenic processes or formed from gases in the atmosphere. The extent to which anthropogenic aerosols affect the radiation budget of Earth is important to better understand anthropogenic climate changes. Aerosol effects on the radiation budget are simulated by complex Earth system models that informed the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Our study addresses why such model experiments show different magnitudes for aerosol radiative effects. The results point to opportunities to further improve models with existing observations of aerosol optical properties and aerosol transport over oceans in addition to the much-studied aerosol effects on clouds."

  • Juli 2023:
    neue Veröffentlichung:

    Latif, M., Bayr, T., Kjellsson, J.  Lübbecke, J.F., Martin, T., Nnamchi, H.C.,  Park, W.,  Savita, A., Sun, J. and  Dommenget, D.: Strengthening atmospheric circulation and trade winds slowed tropical Pacific surface warming. Commun Earth Environ 4, 249 (2023). https://doi.org/10.1038/s43247-023-00912-4

    Summary: "The globally averaged sea-surface temperature (SST) has steadily increased in the last four decades, consistent with the rising atmospheric greenhouse gas concentrations. Parts of the
    tropical Pacific exhibited less warming than the global average or even cooling, which is not
    captured by state-of-the-art climate models and the reasons are poorly understood. Here we
    show that the last four decades featured a strengthening atmospheric circulation and
    stronger trade winds over the tropical Pacific, which counteracted externally-forced SST
    warming. Climate models do not simulate the trends in the atmospheric circulation irrespective of whether an external forcing is applied or not and model bias is the likely reason."

  • Juli 2023:
    neue Veröffentlichung:
    Mu, F., Weide Luiz, E., and Fiedler, S., 2023: "On the dynamics and air-quality impact of the exceptional East Asian dust outbreak in mid-March 2021", Atmospheric Research, 292, https://doi.org/10.1016/j.atmosres.2023.106846.

    Summary: "We assessed the atmospheric dynamics involved in the temporal evolution of the Mongolian cyclone driving the exceptional dust storm in mid-March 2021. The passage of the Mongolian cyclone first induced high dust-emitting winds along its cold front in the Gobi Desert, favouring dust emissions in that region. Subsequently, the Mongolian cyclone caused cold air intrusion into the Taklamakan Desert, promoting the formation of Nocturnal Low-Level Jets (NLLJs) and resulting in subsequent dust emissions in this desert."

 

  • Juni 2023:
    neue Veröffentlichung:
    Weide Luiz, E., and Fiedler, S., 2023: Can convective cold pools lead to the development of low-level jets? Geophysical Research Letters, 50 (11), https://doi.org/10.1029/2023GL103252

    Summary: "Low-level jets (LLJs) typically occur at night due to strong surface cooling. This study provides the first observational evidence that LLJs can also be driven by convectively generated cold pools (CPs), areas of cool and dense air beneath precipitating clouds. CPs can favor temperature inversions with reduced friction of the winds with the surface, as a prerequisite for generating LLJs also during daytime."

  • Juni 2023:
    CACTI workshop  2023: Goal: review the progress since the last TriMIP workshop (TriMIP-3) that brought together the active and collaborative communities of AerChemMIPRAMIPRFMIP, and PDRMIP

    Neu im Team:
    Franz Kanngießer is working on remote sensing of mineral dust aerosol. His current work aims at employing machine learning techniques in service of satellite observations.
    Vidya Varma research Interests are: numerical modelling of climate, impact of anthropogenic aerosols (dust aerosols), radiative forcing and climate
    Feifei Mu research area is: Mongolian cyclones are a precursor to severe dust storms in East Asia. My research aims to systematically clarify the effects of these cyclones on such dust storms, with a specific focus on the dynamic process involved in the outbreaks. I am particularly interested in how Mongolian cyclones contribute to the emissions and transport of dust from various desert regions in East Asia.

  • neue Veröffentlichung:
    Nnamchi, H. C., R. Farneti, N.S. Keenlyside, F. Kucharski, M. Latif, A. Reintges & T. Martin: "Pan-Atlantic decadal climate oscillation linked to ocean circulation." Commun Earth Environ 4, 121 (2023). https://doi.org/10.1038/s43247-023-00781-x.

    Summary: "The pan-Atlantic decadal oscillation exerts far-reaching impacts on regional and global climate fluctuations. This study uncovers a pattern of ocean circulation across the entire Atlantic basin that underlies the surface climate oscillation."

  • Februar 2023:
    neue Veröffentlichung:
    Ding, R., Nnamchi, H.C., Yu, JY. et al. North Atlantic oscillation controls multidecadal changes in the North Tropical Atlantic−Pacific connection. Nature Communications, 14, 862 (2023). https://doi.org/10.1038/s41467-023-36564-3

    Summary: "The North Tropical Atlantic, through its impacts on the Pacific, is key to tropical climate dynamics and predictability. The drivers of multidecadal changes in the North Tropical Atlantic−Pacific connection are poorly understood. Here it is shown that they are mainly controlled by multidecadal variability associated with the North Atlantic Oscillation."

  • Januar 2023:
    Prof. Dr. Stephanie Fiedler ist Professorin für Maritime Meteorologie.

  • Dezember 2022:
    neue Veröffentlichung:
    Wenjuan Huo, Ziniu Xiao, and Liang Zhao, 2022: "Phase-Locked Impact of the 11-Year Solar Cycle on Tropical Pacific Decadal Variability", Journal of Climate, DOI: https://doi.org/10.1175/JCLI-D-21-0595.1

    neue Dissertation:
    Ioana Ivanciu (2022): "Impacts of Increasing Greenhouse Gas Concentrations and of Ozone Changes on the Atmospheric and Oceanic Circulation in the Southern Hemisphere", 210 pp.
    Summary: "This thesis separated the effects of stratospheric ozone changes and of increasing concentrations of anthropogenic greenhouse gases on the atmospheric and oceanic dynamics of the Southern Hemisphere. Under the high emission scenario SSP5-8.5, effects of comparable magnitude were found in the stratosphere, while at the surface and in the ocean the greenhouse gas effect dominate. In addition, the thesis investigated the impact of how the ozone field is treated in climate models and found that the effects of changes in stratospheric ozone are weaker when the ozone field is prescribed rather than calculated interactively."
     
  • November 2022:  Prof. Dr. Mojib Latif erhält den Nachhaltigkeitspreis 2022 der "Sächsischen Hans-Carl-von-Carlowitz-Gesellschaft zur Förderung der Nachhaltigkeit"
     
  • Oktober 2022: Neue Veröffentlichung:
    Ivanciu, Ioana,
    Ndarana, Thando, Matthes, Katja, & Wahl, Sebastian (2022): "On the ridging of the South Atlantic Anticyclone over South Africa: The impact of Rossby wave breaking and of climate change". Geophysical Research Letters, 49, e2022GL099607. doi.org/10.1029/2022GL099607
     
  • September 2022: Neue Veröffentlichung:
    Latif, Mojib: "The roadmap of climate models". Nat Comput Sci 2, 536–538 (2022). https://doi.org/10.1038/s43588-022-00322-0
     
  • Juli 2022: Neue Veröffentlichung:
    Annika Drews, Wenjuan Huo, Katja Matthes, Kunihiko Kodera, and Tim Kruschke: "The Sun's role in decadal climate predictability in the North Atlantic". Atmos. Chem. Phys., 22, 7893–7904, 2022.
     
  • Mai 2022: Neue Veröffentlichung:
    Mojib Latif, 2022: "Countdown (Unsere Zeit läuft ab – was wir der Klimakatastrophe noch entgegensetzen können)", Herder Verlag, 224 Seiten.  
     
  • April 2022: Neue Veröffentlichung:
    Mojib Latif, Jing Sun, Martin Visbeck, and M. Hadi Bordbar, 2022: "Natural variability dominates Atlantic Meridional Overturning since 1900", Nature Climate Change, 12, 455–460.
     
  • Januar 2022: Prof. Dr. Mojib Latif hat die Präsidentschaft der Akademie der Wissenschaften in Hamburg übernommen.
     
  • November 2021: Prof. Dr. Mojib Latif ist designierter Präsident der Akademie der Wissenschaften in Hamburg

    Neue Veröffentlichung:
    Abhishek Savita, Catia M. Domingues, Tim Boyer, et. al.: "Quantifying spread in spatio-temporal changes of upper-ocean heat content estimates: an internationally coordinated comparison", Journal of Climate, 2021. https://doi.org/10.1175/JCLI-D-20-0603.1
     
  • Oktober 2021: Prof. Dr. Mojib Latif erhält höchste Auszeichnung des Verbands Deutscher Vermessungsingenieure: "Goldenes Lot"

    Neue Veröffentlichung:
    Fabio Boeira Dias, Catia M. Domingues, Simon J. Marsland, Stephen R. Rintoul, Petteri Uotila, Russell Fiedler, Mauricio M. Mata, Nathaniel L. Bindoff, and Abhishek Savita: "Subpolar Southern Ocean Response to Changes in the Surface Momentum, Heat, and Freshwater Fluxes under 2xCO2", Journal of Climate, 2021. https://doi.org/10.1175/JCLI-D-21-0161.1
  • September 2021: Neue Veröffentlichung:
    A.S.N. Imbol Nkwinkwa, Rouault M., Keenlyside N.S., Koseki S.: "Impact of the Agulhas Current on southern Africa precipitation: a modelling study", Journal of Climate. Accepted for publication, in press 2021.
     
  • August 2021: Neue Veröffentlichungen:
    (1) Gulev, S. K., P. W. Thorne, J. Ahn, F. J. Dentener, C. M. Domingues, S. Gerland, D. Gong, D. S. Kaufman, H. C. Nnamchi, J. Quaas, J. A. Rivera, S. Sathyendranath, S. L. Smith, B. Trewin, K. von Shuckmann, R. S. Vose (2021): "Changing State of the Climate System." In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.Cambridge University Press. In Press. Available from https://www.ipcc.ch/
    (2) A.S. Imbol Nkwinkwa N., Latif M., and Park W.: "Mean-state dependence of CO2-forced tropical Atlantic sector climate change", Geophysical Research Letters. Accepted for publication, 2021.
    (3) Abhishek Savita, Jan D Zika, Catia M. Domingues, Simon J. Marsland, Gwyn Dafydd Evans, Fabio Boeira Dias, Ryan M. Holmes and Andrew McC Hogg, "Super Residual Circulation: A New Perspective on Ocean Vertical Heat Transport". Journal of Physical Oceanography, 01 Aug 2021. https://doi.org/10.1175/JPO-D-21-0008.1
    (4) Abhishek Savita ist als Mitautor an dem kürzlich veröffentlichten IPCC-Bericht in drei Kapiteln beteiligt (Kapitel 2, 7 und 9).
     
  • Juli 2021: Der Artikel "Wind stress-induced multiyear predictability of annual extratropical North Atlantic sea surface temperature anomalies (A. Reintges, M. Latif, M. H. Bordbar, W. Park, 2020)" war im Jahr 2020 unter den Top 10% der am meisten heruntergeladenen Artikeln des AGU-Journals Geophysical Research Letters!
     
  • 01. Juni 2021: Prof. Dr. Mojib Latif ist neuer Vizepräsident der Akademie der Wissenschaften in Hamburg
     
  • Mai 2021: PD Dr. Joke Lübbecke erhält die Bewilligung für das DFG Projekt “PaCoNi” Küsten-Niños im Pazifik - die Rolle des äquatorialen Wärmeinhaltes und Bezug zur Ausbreitung der Meeresoberflächentemperaturanomalien
     
  • April 2021: Bewilligung einer Marie Skłodowska-Curie Individual Fellowship “DivPredSkill” für Dr. Annika Reintges, auszuführen an der University of Reading (UK) in Zusammenarbeit mit Dr. Jon Robson, Prof. Dr. Rowan Sutton (University of Reading, UK) und Dr. Stephen Yeager (NCAR, USA)
     
  • Februar 2021: Dr. Hyacinth Nnamchi erhält die Bewilligung für das DFG Projekt NOVEL - Bewertung der meridionalen gegenüber den zonalen Mechanismen des atlantischen Nino
     
  • Dezember 2020: PD Dr. Joke Lübbecke hat für die Dauer eines Jahres eine Vertretungsprofessur in der Abteilung Maritime Meteorologie übernommen.
     
  • Neu im Team:
    seit Januar 2023: Qi Zhang
    seit Juni 2022: Dr. Sayantani Ojha (Postdoc) seit April 2022: Yingxue Liu (Promovierende)
    seit Juli 2021: Mehmet Sedat Gözlet (Promovierender)
    seit Mai 2021: Malin Ödalen (Postdoc), Abhishek Savita (Postdoc), Médéric St-Pierre (Promovierender),