North Atlantic and Pacific Quasi-Stationary Parts of Atmospheric Rivers and Their Implications for East Asian Monsoon Onset

• Published in: Geophysical Research Letters
• Main Authors: Lee, H.-I., Mitchell, J.L., Tripati, A., Lora, J.M., Chen, G., Ding, Q.
• Other Authors: University of California Los Angeles (UCLA), University of California (UC), Department of Atmospheric and Oceanic Sciences Los Angeles (AOS), University of California (UC)-University of California (UC), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Yale University New Haven, National Sleep Foundation, NSF: ANR‐10‐LABX‐19University of California, Los Angeles, UCLA
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: atmospheric rivers; monsoon; Rossby wave breaking; [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology; Pacific; North Atlantic
• Online Access: https://hal.science/hal-02944474; https://hal.science/hal-02944474/document; https://hal.science/hal-02944474/file/2019GL084272.pdf; https://doi.org/10.1029/2019GL084272

International audience Using a global space-time diagram of column water vapor (CWV) at 30° N latitude from daily reanalysis data, we find two quasi-stationary parts of atmospheric rivers (QSARs) that feature locally enhanced CWV and evolve from the Eastern Pacific/Atlantic basins in the winter to the Western Pacific/Atlantic in the summer. East Asian Summer Monsoon onset coincides with the time CWV in the Pacific QSAR first exceeds 40 mm, which also typically occurs just before it makes landfall. QSARs exist in 39-year (1979–2017) daily climatological CWV, demonstrating the seasonal cycles of these features are quasi-stationary and potentially useful for monsoon onset prediction. East Asian Summer Monsoon onset is particularly predictable following El Niño-Southern Oscillation, consistently occurring 25–40 days after the QSAR crosses the dateline. Analysis of local wave activity reveals QSARs as fronts of wave breakings, thus opening a new window into dynamics of subtropical monsoon extensions. ©2019. American Geophysical Union. All Rights Reserved.