Articles | Volume 21, issue 10
https://doi.org/10.5194/cp-21-1801-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/cp-21-1801-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 Oct 2025
Research article |
| 22 Oct 2025
| 22 Oct 2025
Observation error estimation in climate proxies with data assimilation and innovation statistics
Institute of Advanced Academic Research, Chiba University, Chiba, Japan
Center for Environmental Remote Sensing, Chiba University, Chiba, Japan
Diego S. Carrió
Department of Physics, Universitat de les Illes Balears, Palma, Spain
Quentin Dalaiden
Nansen Environmental and Remote Sensing Center, Bergen, Norway
Jarrah Harrison-Lofthouse
School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Melbourne, Australia
Shunji Kotsuki
Institute of Advanced Academic Research, Chiba University, Chiba, Japan
Center for Environmental Remote Sensing, Chiba University, Chiba, Japan
Kei Yoshimura
Institute of Industrial Science, The University of Tokyo, Kashiwa, Japan
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Short summary
Short summary
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Ryan L. Fogt, Quentin Dalaiden, and Gemma K. O'Connor
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Antarctic sea ice is rapidly changing, with record lows set in 2017, 2022, and 2023 following decades of increase. To place these changes in a longer historical context, reconstructions have been created; however, they are quite different prior to observations. Here we find that the differences are more strongly tied to the implied connection of each reconstruction with the atmospheric circulation rather than differences in seasonality or geographic representation.
Kenta Kurosawa, Shunji Kotsuki, and Takemasa Miyoshi
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Christian Ferrarin, Florian Pantillon, Silvio Davolio, Marco Bajo, Mario Marcello Miglietta, Elenio Avolio, Diego S. Carrió, Ioannis Pytharoulis, Claudio Sanchez, Platon Patlakas, Juan Jesús González-Alemán, and Emmanouil Flaounas
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Mao Ouyang, Keita Tokuda, and Shunji Kotsuki
Nonlin. Processes Geophys., 30, 183–193, https://doi.org/10.5194/npg-30-183-2023, https://doi.org/10.5194/npg-30-183-2023, 2023
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This research found that weather control would change the chaotic behavior of an atmospheric model. We proposed to introduce chaos theory in the weather control. Experimental results demonstrated that the proposed approach reduced the manipulations, including the control times and magnitudes, which throw light on the weather control in a real atmospheric model.
Di Wang, Lide Tian, Camille Risi, Xuejie Wang, Jiangpeng Cui, Gabriel J. Bowen, Kei Yoshimura, Zhongwang Wei, and Laurent Z. X. Li
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To better understand the spatial and temporal distribution of vapor isotopes, we present two vehicle-based spatially continuous snapshots of the near-surface vapor isotopes in China during the pre-monsoon and monsoon periods. These observations are explained well by different moisture sources and processes along the air mass trajectories. Our results suggest that proxy records need to be interpreted in the context of regional systems and sources of moisture.
Diego S. Carrió
Nat. Hazards Earth Syst. Sci., 23, 847–869, https://doi.org/10.5194/nhess-23-847-2023, https://doi.org/10.5194/nhess-23-847-2023, 2023
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The accurate prediction of medicanes still remains a key challenge in the scientific community because of their poor predictability. In this study we assimilate different observations to improve the trajectory and intensity forecasts of the Qendresa Medicane. Results show the importance of using data assimilation techniques to improve the estimate of the atmospheric flow in the upper-level atmosphere, which has been shown to be key to improve the prediction of Qendresa.
Farahnaz Khosrawi, Kinya Toride, Kei Yoshimura, Christopher Diekmann, Benjamin Ertl, Frank Hase, and Matthias Schneider
EGUsphere, https://doi.org/10.5194/egusphere-2022-1408, https://doi.org/10.5194/egusphere-2022-1408, 2022
Preprint withdrawn
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We assess with an Observation System Simulation Experiment the potential of mid-tropospheric water isotopologue data for constraining uncertainties in meteorological analysis fields in the tropics. Our assimilation experiments indicate that isotopologue observations have the potential to reduce the uncertainties of diabatic heating rates and precipitation in the tropics and in consequence offer potential for improving meteorological analysis in the tropical regions.
Shunji Kotsuki, Takemasa Miyoshi, Keiichi Kondo, and Roland Potthast
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Jeanne Rezsöhazy, Quentin Dalaiden, François Klein, Hugues Goosse, and Joël Guiot
Clim. Past, 18, 2093–2115, https://doi.org/10.5194/cp-18-2093-2022, https://doi.org/10.5194/cp-18-2093-2022, 2022
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Using statistical tree-growth proxy system models in the data assimilation framework may have limitations. In this study, we successfully incorporate the process-based dendroclimatic model MAIDEN into a data assimilation procedure to robustly compare the outputs of an Earth system model with tree-ring width observations. Important steps are made to demonstrate that using MAIDEN as a proxy system model is a promising way to improve large-scale climate reconstructions with data assimilation.
Janica C. Bühler, Josefine Axelsson, Franziska A. Lechleitner, Jens Fohlmeister, Allegra N. LeGrande, Madhavan Midhun, Jesper Sjolte, Martin Werner, Kei Yoshimura, and Kira Rehfeld
Clim. Past, 18, 1625–1654, https://doi.org/10.5194/cp-18-1625-2022, https://doi.org/10.5194/cp-18-1625-2022, 2022
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We collected and standardized the output of five isotope-enabled simulations for the last millennium and assess differences and similarities to records from a global speleothem database. Modeled isotope variations mostly arise from temperature differences. While lower-resolution speleothems do not capture extreme changes to the extent of models, they show higher variability on multi-decadal timescales. As no model excels in all comparisons, we advise a multi-model approach where possible.
Nicolas Ghilain, Stéphane Vannitsem, Quentin Dalaiden, Hugues Goosse, Lesley De Cruz, and Wenguang Wei
Earth Syst. Sci. Data, 14, 1901–1916, https://doi.org/10.5194/essd-14-1901-2022, https://doi.org/10.5194/essd-14-1901-2022, 2022
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Modeling the climate at high resolution is crucial to represent the snowfall accumulation over the complex orography of the Antarctic coast. While ice cores provide a view constrained spatially but over centuries, climate models can give insight into its spatial distribution, either at high resolution over a short period or vice versa. We downscaled snowfall accumulation from climate model historical simulations (1850–present day) over Dronning Maud Land at 5.5 km using a statistical method.
Farahnaz Khosrawi, Kinya Toride, Kei Yoshimura, Christopher J. Diekmann, Benjamin Ertl, Frank Hase, and Matthias Schneider
Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2021-49, https://doi.org/10.5194/wcd-2021-49, 2021
Revised manuscript not accepted
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We assess with an Observation System Simulation Experiment the potential of mid-tropospheric water isotopologue data for constraining uncertainties in meteorological analysis fields in the tropics. Our assimilation experiments indicate that isotopologue observations have the potential to reduce the uncertainties of diabatic heating rates and meteorological variables in the tropics and in consequence offer potential for improving meteorological analysis in the tropical regions.
Hugues Goosse, Quentin Dalaiden, Marie G. P. Cavitte, and Liping Zhang
Clim. Past, 17, 111–131, https://doi.org/10.5194/cp-17-111-2021, https://doi.org/10.5194/cp-17-111-2021, 2021
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Polynyas are ice-free oceanic areas within the sea ice pack. Small polynyas are regularly observed in the Southern Ocean, but large open-ocean polynyas have been rare over the past decades. Using records from available ice cores in Antarctica, we reconstruct past polynya activity and confirm that those events have also been rare over the past centuries, but the information provided by existing data is not sufficient to precisely characterize the timing of past polynya opening.
Marie G. P. Cavitte, Quentin Dalaiden, Hugues Goosse, Jan T. M. Lenaerts, and Elizabeth R. Thomas
The Cryosphere, 14, 4083–4102, https://doi.org/10.5194/tc-14-4083-2020, https://doi.org/10.5194/tc-14-4083-2020, 2020
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Surface mass balance (SMB) and surface air temperature (SAT) are correlated at the regional scale for most of Antarctica, SMB and δ18O. Areas with low/no correlation are where wind processes (foehn, katabatic wind warming, and erosion) are sufficiently active to overwhelm the synoptic-scale snow accumulation. Measured in ice cores, the link between SMB, SAT, and δ18O is much weaker. Random noise can be removed by core record averaging but local processes perturb the correlation systematically.
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Short summary
Data assimilation (DA) has been used to reconstruct paleoclimate fields. DA integrates model simulations and climate proxies based on their error sizes. Consequently, error information is vital for DA to function optimally. This study estimated observation errors using "innovation statistics" and demonstrated that DA with estimated errors outperformed previous studies.
Data assimilation (DA) has been used to reconstruct paleoclimate fields. DA integrates model...
