Wu, Chi-Hua吳奇樺

Associate Research Fellow

Research Interests

My research lies in the field of monsoon, with a longstanding interest in the origin and process mechanisms of the East Asian seasonality. Investigating seasonal and regional mechanisms of monsoons is the general goal of my research. How to conduct climate diagnostics, by combining empirical data analysis and model simulation, and how to pinpoint the physical processes affecting climate variability and change are the central questions that drive most of my research activities. My research projects aim to understand the Afro–Asian monsoon evolution and change in Earth history. From basic to application levels of science, our previous and ongoing monsoon studies include topographic effects, synchronous (among regions) and asymmetric seasonality (regarding annual cycle), decadal changes, and paleo-monsoons and orbital impact. We have been being provided insights into paleoclimate dynamics, climate change, and climate modeling with respect to monsoon behaviors, and raising concern about state-dependent noise in climate change studies.

Representative Publications

Wu, C. H.*, and P. C. Tsai, (2020): Obliquity-driven changes in East Asian seasonality. Global and Planetary Change, 189, 103161. https://doi.org/10.1016/j.gloplacha.2020.103161

Wu, C. H.*, P. C. Tsai, and N. Freychet, (2020): Changing dynamical control of early Asian summer monsoon in the mid-1990s. Climate Dynamics, 54(1), 85-98. doi:10.1007/s00382-019-04989-6

Wu, C. H.*, I. C. Tsai, P. C. Tsai, and Y. S. Tung, (2019): Large-scale seasonal control of air quality in Taiwan. Atmospheric Environment, 214, 116868. https://doi.org/10.1016/j.atmosenv.2019.116868

Wu, C. H.*, S. Y. Wang, and H. H. Hsu, (2018): Large-scale control of the Arabian Sea monsoon inversion in August. Climate Dynamics, 51(7), 2581-2592. DOI: 10.1007/s00382-017-4029-7

Wu, C. H.*, W. R. Huang, and S. Y. Wang, (2018): Role of Indochina Peninsula topography in precipitation seasonality over East Asia. Atmosphere, 9(7): 255. doi: 10.3390/atmos9070255 (Special Issue Monsoons)

Wu, C. H.*, S. Y. Lee, and J. C. H. Chiang, (2018): Relative influence of precession and obliquity in the early Holocene: topographic modulation of subtropical seasonality during the Asian summer monsoon. Quaternary Science Reviews, 191, 238-255. https://doi.org/10.1016/j.quascirev.2018.05.021 

Wu, C. H.*, M. D. Chou, and Y. H. Fong, (2018): Impact of the Himalayas on the Meiyu-Baiu migration. Climate Dynamics, 50(3), 1307-1319. DOI: 10.1007/s00382-017-3686-x

Wu, C. H.*, (2017): Thermodynamic and dynamic influences in the Far East-Okhotsk region on stagnant Meiyu-Baiu. J. Geophys. Res. Atmos., 122, 7276–7288. doi:10.1002/2017JD026558

Wu, C. H.*, and H. H. Hsu, (2016): Role of the Indochina Peninsula narrow mountains in modulating the East Asia-Western North Pacific summer monsoon. J. Climate, 29, 4445-4459. http://dx.doi.org/10.1175/JCLI-D-15-0594.1

Wu, C. H.*, J. C. H. Chiang, H. H. Hsu, and S. Y. Lee, (2016): Orbital control of the western North Pacific summer monsoon. Climate Dynamics, 46(3), 897-911. DOI:10.1007/s00382-015-2620-3

Highlights

The role of Indochina Peninsula topography in East Asian seasonality Stage–wise precipitation over East Asia, primarily from spring to summer, is influenced by nearby monsoons and can be topographically driven. Our modeling works pointed to the role of the topographical processes of the Indochina Peninsula in driving the rapid monsoonal transitions, which correspond to the early summer vertical circulation coupling over the Bay of Bengal–Indochina Peninsula and the late–July WNP monsoon onset. Therefore, asymmetric characteristics of East Asian seasonality could be partly attributed to the existence of Indochina Peninsula.

Decadal climate changes The present-day monsoon area may have expanded in timescales of short-term climate, and in some regions the result is comparable with paleoclimate records. It is instructive to understand how sensitive of the large-scale dry-wet patterns to climate variability and even macroclimate change. Whether decadal changes could be considered a changing climatology may be a further challenge. In the 1990s, observations have confirmed a changing dynamical control of the Asian summer monsoon, with a novel insight into a growing midlatitude influence on the early Asian summer monsoon; with this regard, the continental thermal control as thought a dominant driver of summer monsoon can be comparable.

Seasonal perspective on the role of precession and obliquity in the early Holocene On orbital timescales, higher summer insolation is thought to strengthen the continental monsoon while weakening the maritime monsoon in the northern hemisphere. Presently, interior Asian continental heating drives the South and East Asian monsoons in late spring–early summer. The broad-scale monsoonal circulation further expands zonally in July–August, corresponding to the development of summer monsoons in West Africa and oceanic regions. Tropical and oceanic heating becomes crucial in late summer. With this seasonal regard, our modeling results suggested that precession dominates the atmospheric heating change over the Tibetan Plateau–Himalayas and Maritime Continent, whereas obliquity is responsible for the heating change over the equatorial Indian Ocean. Thus, precession and obliquity can play contrasting roles in driving the monsoons on orbital timescales.

Coordinated evolution of the Holocene Afro–Asian summer monsoons The asynchronous Holocene evolution of Afro–Asian summer monsoons provides valuable insight into climate dynamics and changes. Although still a matter of debate, monsoons changed somewhat abruptly in the mid-Holocene. By investigating data–model synthesis, with the major focus on the differential seasonal responses of solar insolation and monsoons to orbital changes, we observed coordinated and stepwise seasonal evolution of summer monsoons across the mid-Holocene. Prior to the mid-Holocene, insolation had decreased considerably during the early summer; the continental monsoons migrated southeastward, which corresponded to a more pronounced rainy season in coastal East Asia. By contrast, late-summer insolation did not decrease until the mid-Holocene. The continued weakening of the continental monsoons, combined with weakened insolation, accelerated a large-scale migration of monsoons.

  • Ph.D.
    Atmospheric Sciences
    National Taiwan University, Taiwan (2010)
  • B.S.
    Earth Sciences
    National Taiwan Normal University, Taiwan (2001)
  • (02) 2787-5934

  • chhwu

  • M.LAB

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