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DOI： 10.5194/egusphere-2025-6285

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Publishing type：Research paper (scientific journal)  

DOI： 10.22541/essoar.171440105.50340530/v1

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Language：Japanese   Publisher：Meteorological Society of Japan  

In this study, we introduce a new seasonal prediction system using an atmosphere–ocean-coupled general circulation model called CFES (hereafter referred to as CFES ESPreSSO). We compare its prediction skill of the interannual variability of the surface air temperature (SAT) and precipitation anomalies with that of the SINTEX-F2 seasonal prediction system. We find that CFES ESPreSSO has a higher skill in predicting the SAT variability in January-February-March over East Asia and northeastern North America than SINTEX-F2, while the following season (April-May-June), SINTEX-F2 provides better predictions of the SAT variability over the Maritime Continent and subtropical North Pacific. Meanwhile, CFES better predicts the SAT variability in July-August-September over Eurasia and Arctic, and it continues to be so over the following season (October-November-December) over Eurasia. However, the prediction skill of SINTEX-F2 is generally better in the tropics (e.g., SAT in the subtropical North Pacific, SAT and precipitation in the Maritime Continent). Regarding climate indices, CFES shows a better prediction skill for the Atlantic Niño and Ningaloo Niño indices, whereas SINTEX-F2 is generally better for El Niño and the Indian Ocean dipole mode. These results suggest that for improved seasonal forecasting, it is beneficial to consider a multi-model approach, leveraging the respective strengths of each model.

DOI： 10.2151/sola.2024-013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Geophysical Union ({AGU})  

DOI： 10.1029/2022GL097791

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus {GmbH}  

<jats:p>Abstract. Although conventionally attributed to dry dynamics, increasing evidence points to a key role of moist dynamics in the formation and maintenance of blocking events. The source of moisture crucial for these processes, however, remains elusive. In this study, we identify the moisture sources responsible for latent heating associated with the wintertime Euro-Atlantic blocking events detected over 31 years (1979–2010). To this end, we track atmospheric particles backward in time from the blocking centres for a period of 10 d using an offline Lagrangian dispersion model applied to atmospheric reanalysis data. The analysis reveals that 28 %–55 % of particles gain heat and moisture from the ocean over the course of 10 d, with higher percentages for the lower altitudes from which particles are released. Via large-scale ascent, these moist particles transport low-potential-vorticity (PV) air of low-altitude, low-latitude origins into the upper troposphere, where the amplitude of blocking is the most prominent, in agreement with previous studies. The PV of these moist particles remains significantly lower compared to their dry counterparts throughout the course of 10 d, preferentially constituting blocking cores. Further analysis reveals that approximately two-thirds of the moist particles source their moisture locally from the Atlantic, while the remaining one-third of moist particles source it from the Pacific. There is also a small fraction of moist particles that take up moisture from both the Pacific and Atlantic basins, which undergo a large-scale uplift over the Atlantic using moisture picked up over both basins. The Gulf Stream and Kuroshio and their extensions as well as the eastern Pacific northeast of Hawaii not only provide heat and moisture to moist particles but also act as “springboards” for their large-scale, cross-isentropic ascent, where its extent strongly depends on the humidity content at the time of the ascent. While the particles of Atlantic origin swiftly ascend just before their arrival at blocking, those of Pacific origin begin their ascent a few days earlier, after which they carry low-PV air in the upper troposphere while undergoing radiative cooling just as dry particles. A previous study identified a blocking maintenance mechanism, whereby low-PV air is selectively absorbed into blocking systems to prolong blocking lifetime. As they used an isentropic trajectory analysis, this mechanism was regarded as a dry process. We found that these moist particles that are fuelled over the Pacific can also act to maintain blocks in the same manner, revealing that what appears to be a blocking maintenance mechanism governed by dry dynamics alone can, in fact, be of moist origin.
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DOI： 10.5194/wcd-2-819-2021

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Presentation type：Public lecture, seminar, tutorial, course, or other speech  

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Type：Academic society, research group, etc. 

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Type：Academic society, research group, etc. 

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Type：Academic society, research group, etc. 

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