大氣長河是強勁且呈狹長帶狀的水氣傳輸帶，在供應中緯度地區水資源的同時，卻也常因行經山區地帶而形成具破壞性的降雨。由於大氣長河在熱帶往中高緯度輸送水氣的水文循環過程中扮演著重要的角色，因此數十年來關於大氣長河的探討，在中緯度始終備受矚目。近年來越來越多的研究，開始以大氣長河的角度討論相對低緯度地區的水氣傳送。本研究的基礎，主要架構在前人設計的大氣長河自動偵測演算法。該客觀偵測法以圖型辨識分析垂直積分水氣傳送距平場，並擷取具大氣長河特徵的水氣輸送。

本文統計在1981年至2015年西北太平洋與東亞地區的大氣長河氣候特性，討論不同時間尺度的氣候振盪對於大氣長河的調控，歸納35年間觸陸大氣長河對於臺灣大雨事件的影響。此研究進而修改部分偵測演算法的辨識過程與輸出，並以NASA MERRA-2再分析資料計算垂直積分水氣傳送。在氣候特性上，東亞和西太平洋地區大氣長河的發生頻率與生成個數，整體而言在北半球夏季均明顯高於北半球冬季，明顯受到東亞夏季季風的影響。兩個主要的大氣長河生成區，分別位於青藏高原東南側與日本東南側的海域，但兩地大氣長河生成的機制與季節有明顯差異。東亞大氣長河的發生頻率在受到聖嬰與太平洋十年振盪等年代際影響外，本文指出北半球夏季季內振盪（Boreal Summer Intraseasonal Oscillation）對於大氣長河季內尺度變異的重要性。同時，北半球夏季季內振盪的第二模態和登陸臺灣的大氣長河數量與降雨強度有顯著關聯。根據35年的統計，在夏季約有20 %-30 %登陸臺灣的大氣長河，會在中南部山區降下大雨等級以上的雨量。在春季與冬季，位於臺灣西半部地區大雨等級以上的降雨事件約有60 %-90 %是由大氣長河貢獻。

Atmospheric rivers (ARs) are intense water vapor conveyor belt with filament-like shape contributing most of the water resources to societies within the Midlatitude region but also generating impactful rainfall over mountainous topography. Researches on ARs in the Midlatitude were prevalent throughout these decades since AR acts such an important role in the global hydrological cycle by transporting water vapor from the Tropics to the Midlatitude. Analysis of hydrometeorology in lower latitude basing on the viewpoint of AR appears more frequently in recent years. Fundamentals of this research base on the automatic detection algorithm developed by the previous study on ARs. The objective detection method analyzes the anomalous vertically integrated water vapor transport (IVT) with image identification processes, and acquires the AR-like moisture transport features.

Climatological characteristics of ARs over East Asia and the Western North Pacific (WNP) in 1981-2015 are statisticized. Modulations on AR from climate oscillations with different scale and also the impacts of landfalling ARs on heavy rainfall events in Taiwan are analyzed. Parts of the processes and output of the original detection algorithm are modified in this study, while IVT is computed from the reanalysis data adopted from NASA Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2).

In general, both the occurrence frequency and genesis numbers of ARs over East Asia and the WNP are apparently higher in boreal summer than winter, which is obviously affected by the East Asian summer monsoon. Two primary AR genesis regions located at the southeastern side of the Tibetan Plateau and the sea areas at the southeastern side of Japan. However, distinct formation mechanism and season of ARs exist between the two regions. Besides the interannual and interdecadal influences of El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) on AR frequency over East Asia, this research emphasized the importance of Boreal Summer Intraseasonal Oscillation (BSISO) on the intraseasonal variability of AR. Meanwhile, evident relations of the second mode of BSISO and the numbers of landfalling ARs as well as the intensity of accompanied rainfall in Taiwan are presented. According to the 35-year statistics, 20 %-30 % of landfalling ARs induce heavy rainfall over the mountainous area in the Central and Southern Taiwan in summer. Moreover, 60 %-90 % of heavy rainfall events occurred in the western part of Taiwan during spring and winter were contributed by landfalling ARs.

陳映如，2017：西北太平洋大氣長河及其受熱帶氣旋之影響，國立臺灣大學大氣科學研究所碩士論文。
陳詩庭，2017：梅雨季西南氣流特性對台灣降水分佈影響之理想模擬研究，國立臺灣師範大學地球科學研究所碩士論文。
楊宜庭，2015：西行颱風伴隨西南氣流之環境場特徵分析，國立中央大學大氣物理研究所碩士論文。
Akiyama, T. Ageostrophic low-level jet stream in the Baiu season associated with heavy rainfalls over the sea area. J. Meteor. Soc. Japan, 1973, 51, 205-208.
Baggett, C. F., E. A. Barnes, E. D. Maloney, and B. D. Mundhenk. Advancing atmospheric river forecasts into subseasonal-to-seasonal timescales. Geophys. Res. Lett., 2017, 44, 7528-7536.
Brands, S., J. M. Gutiérrez, and D. San-Martín. Twentiethcentury atmospheric river activity along the west coasts of Europe and North America: Algorithm formulation, reanalysis uncertainty and links to atmospheric circulation patterns. Climate Dyn., 2017, 48, 2771–2795. doi:10.1007/s00382-016-3095-6.
Chang, C. P., Ed. East Asian Monsoon. Vol. 2, World Scientific Series on Meteorology of East Asia, World Scientific, 2004, 600 pp.
Chen, G. T. J. Research on the phenomena of Meiyu during the past quarter century: An overview. World Scientific Publishing Co., 2004, East Asian Monsoon (World Scientific Series for Meteorology of East Asia), Vol. 2, C. P. Chang, Ed., 357-403.
Chen, G. T. J., C. C. Wang, and L. F. Lin. A diagnostic study of a retreating Mei-Yu front and the accompanying low-level jet formation and intensification. Mon. Wea. Rev., 2006, 134, 874–896.
Chen, G. T. J., C. C. Wang, and S. W. Chang. A diagnostic case study of mei-yu frontogenesis and development of wavelike frontal disturbances in the subtropical environment. Mon. Wea. Rev., 2008, 136, 41–61. doi:10.1175/2007MWR1966.1.
Choi, W. and K. Y., Kim. Summertime variability of the western North Pacific subtropical high and its synoptic influences on the east Asian weather. Scientific Reports, 2019, 9, 7865.
Chou, L. C., C. P. Chang, and R. T. Williams. A numerical simulation of the Mei-Yu front and the associated low level jet. Mon. Wea. Rev., 1990, 118, 1408-1428.
Eiras-Barca, J., A. M. Ramos, J. G. Pinto, R. M. Trigo, M. L. R. Liberato, and G. Miguez-Macho. The concurrence of atmospheric rivers and explosive cyclogenesis in the North Atlantic and North Pacific basins. Earth Syst. Dyn., 2018, 9, 91–102. doi:10.5194/esd-9-91-2018.
Espinoza, V., D. E. Waliser, B. Guan, D. A. Lavers, and F. M. Ralph. Global analysis of climate change projection effects on atmospheric rivers. Geophys. Res. Lett., 2018, 45, 4299–4308. doi:10.1029/2017GL076968.
Gill, A. E. Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc., 1980, 106, 447–462. doi:10.1002/qj.49710644905.
Gimeno, L., R. Nieto, M. Vazquez, and D. A. Lavers. Atmospheric rivers: A mini-review. Front. Earth Sci., 2014, doi:10.3389/feart.2014.00002. Gleick, P. H. (1996), Water resources, in Encyclopedia of Climate and Weather, Vol. 2, S. H. Schneider, Ed., 817-823, Oxford Univ. Press, New York.
Gimeno, L., F. Dominguez, R. Nieto, R. Trigo, A. Drumond, C. J. C. Reason, A. S. Taschetto, A. M. Ramos, R. Kumar, and J. Marengo. Major mechanisms of atmospheric moisture transport and their role in extreme precipitation events. Ann. Rev. Environ. Res., 2016, 41, 117–141.
Goldenson, N., L. R. Leung, C. M. Bitz, and E. Blanchard-Wrigglesworth. Influence of Atmospheric River Events on Mountain Snowpack of the Western U.S. J. Clim. 2018, 31, 9921–9940.
Gorodetskaya, I. V., et al. The role of atmospheric rivers in anomalous snow accumulation in East Antarctica. Geophys. Res. Lett. 2014, 41, 6199–6206.
Guan, B. and D. E. Waliser. Detection of atmospheric rivers: Evaluation and application of an algorithm for global studies. J. Geophys. Res.-Atmos., 2015, 120, 12514–12535. doi:10.1002/2015jd024257.
Guirguis, K., A. Gershunov, R. E. S. Clemesha, T. Shulgina, A. C. Subramanian, and F. M. Ralph. Circulation drivers of atmospheric rivers at the North American West Coast. Geophys. Res. Lett., 2018, 45, 12576–12584. doi:10.1029/2018GL079249.
Hagos, S., L. R. Leung, Q. Yang, C. Zhao, and J. Lu: Resolution and dynamical core dependence of atmospheric river frequency in global model simulations, J. Climate, 2015, 28, 2764–2776. doi:10.1175/jcli-d-14-00567.1.
Hirata, H., R. Kawamura, M. Kato, and T. Shinoda. Influential role of moisture supply from the Kuroshio/Kuroshio Extension in the rapid development of an extratropical cyclone. Mon. Wea. Rev., 2015, 143, 4126–4144. doi:10.1175/MWR-D-15-0016.1.
Hoskins, B. J., and D. J. Karoly. The steady linear response of a spherical atmosphere to thermal and orographic forcing. J. Atmos. Sci., 1981, 38, 1179–1196. doi:10.1175/1520-0469(1981)038<1179:TSLROA>2.0.CO;2.
Hsu, H. H., and Y. T. Chen. Simulation and projection of circulations associated with atmospheric rivers along the North American northeast coast. J. Climate, 2020, 33, 5673-5695. doi:10.1175/JCLI-D-19-0104.1.
Huang, W. R., P. Y. Liu, J. H. Chen, and L. Deng. Impact of Boreal Summer Intra-Seasonal Oscillations on the Heavy Rainfall Events in Taiwan during the 2017 Meiyu Season. Atmosphere, 2019, 10, 205. doi:10.3390/atmos10040205.
Hung, C. W., H. J. Lin, P. K. Kao, M. F. Shih, and W. Y. Fong. Boreal summer intraseasonal oscillation impact on western North Pacific typhoons and rainfall in Taiwan. Terr. Atmos. Ocean. Sci., 2016, 27, 893-906.
IPCC. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 2013, Cambridge, United Kingdom and New York, NY, USA, 1535 pp. doi:10.1017/CBO9781107415324.
Jiang, N., K. Cheung, K. Luo, P. J. Beggs, and W. Zhou. On two different objective procedures for classifying synoptic weather types over east Australia. Int. J. Climatol., 2012, 32, 1475–1494.
Kamae Y., W. Mei, S. P. Xie. Climatological relationship between warm season atmospheric rivers and heavy rainfall over East Asia. J. Meteorol. Soc. Jpn, 2017, 95, 411–431.
Kamae, Y., W. Mei, and S. P. Xie. Ocean warming pattern effects on future changes in East Asian atmospheric rivers. Environ. Res. Lett. 2019, 14, 054019.
Kamae, Y., W. Mei, S. P. Xie, M. Naoi, and H. Ueda. Atmospheric rivers over the Northwestern Pacific: Climatology and interannual variability. J. Climate, 2017, 30, 5605-5619.
Kikuchi K., B. Wang, Y. Kajikawa. Bimodal representation of the tropical intraseasonal oscillation. Clim Dyn., 2011, 38, 1989–2000. doi:10.1007/s00382-011-1159-1.
Knippertz, P., H. Wernli, and G. Gläser. A global climatology of tropical moisture. J. Climate, 2013, 26, 3031–3045. doi:10.1175/JCLI-D-12-00401.1.
Kuwano-Yoshida, A., and S. Minobe. Storm-track response to SST fronts in the Northwestern Pacific region in an AGCM. J. Clim. 2017, 30, 1081–1102.
Lavers, D. A., G. Villarini, R. P. Allan, E. F. Wood, and A. J. Wade. The detection of atmospheric rivers in atmospheric reanalyses and their links to British winter floods and the large-scale climatic circulation, J. Geophys. Res.-Atmos., 2012, 117, D20106, doi:10.1029/2012jd018027.
Lavers, D. A., and G. Villarini. The nexus between atmospheric rivers and extreme precipitation across Europe. Geophys. Res. Lett., 2013, 40, 3259–3264. doi:10.1002/grl.50636.
Lavers, D. A., F. M. Ralph, D. E. Waliser, A. Gershunov, and M. D. Dettinger. Climate change intensification of horizontal water vapor transport in CMIP5, Geophys. Res. Lett., 2015, 42, 5617–5625. doi:10.1002/2015GL064672.
Lee J. Y., B. Wang, M. C. Wheeler, X. H. Fu, D. E. Waliser, I. S. Kang. Real-time multivariate indices for the boreal summer intraseasonal oscillation over the Asian summer monsoon region. Clim Dyn., 2012, 40, 493–509.
Liu, X., X. Ren, and X. Q. Yang. Decadal changes in multi-scale water vapor transport and atmospheric river associated with the pacific decadal oscillation and the north pacific gyre oscillation, J. Hydrometeorol., 2015, 17, 273– 285, doi:10.1175/JHM-D-14-0195.1.
Liu, Y., et al. Application of deep convolutional neural networks for detecting extreme weather in climate datasets. 2016, arXiv:1605.01156 [cs.CV].
Lora, J. M., J. L. Mitchell, C. Risi, and A. E. Tripati. North Pacific atmospheric rivers and their influence on western North America at the Last Glacial Maximum, Geophys. Res. Lett., 2017, 44, 1051–1059. doi:10.1002/2016gl071541.
Mantua, N.J., and S. R. Hare. The Pacific Decadal Oscillation. J. Oceanogr., 2002, 58, 35-44.
Meehl, G. A., and Coauthors. Decadal prediction: Can it be skillful? Bull. Amer. Meteor. Soc., 2009, 90, 1467–1485. doi:10.1175/2009BAMS2778.1.
Mundhenk, B. D., E. A. Barnes, and E. D. Maloney. All season climatology and variability of atmospheric river frequencies over the North Pacific. J. Climate, 2016, 29, 4885-4903. doi:10.1175/JCLI-D-15-0655.1.
Mundhenk, B. D., E. A. Barnes, E. D. Maloney, and C. F. Baggett. Skillful empirical subseasonal prediction of landfalling atmospheric river activity using the Madden-Julian oscillation and quasi-biennial oscillation. npj Climate Atmos. Sci., 2018, 1, 20177, doi:10.1038/s41612-017-0008-2.
Nayak, M. A., G. Villarini, and D. A. Lavers. On the skill of numerical weather prediction models to forecast atmospheric rivers over the central United States. Geophys. Res. Lett., 2014, 41, 4354-4362.
Newell, R. E., N. E. Newell, Y. Zhu, and C. Scott. Tropospheric rivers? A pilot study. Geophys. Res. Lett., 1992, 19, 2401-2404. doi:10.1029/92GL02916.
Payne, A. E., and G. Magnusdottir. Dynamics of landfalling atmospheric rivers over the North Pacific in 30 years of MERRA reanalysis. J. Climate, 2014, 27, 7133-7150.
Payne, A. E., et al. Responses and impacts of atmospheric rivers to climate change. Nat. Rev. Earth Environ., 2020, 1, 143–157.
Peixoto, J. P., and A. H. Oort. Physics of Climate. American Institute of Physics, 1998, New York, USA, 520 pp.
Ralph, F. M., J. J. Rutz, J. M. Cordeira, M. Dettinger, M. Anderson, D. Reynolds, L. J. Schick, and C. Smallcomb. A scale to characterize the strength and impacts of atmospheric rivers. B. Am. Meteorol. Soc., 2019, 100(2), 269-289. doi:10.1175/BAMS-D-18-0023.1.
Ralph, F. M., and M. D. Dettinger. Storms, floods, and the science of atmospheric rivers. Eos, 2011, 92, 265-266. doi:10.1029/2011EO320001.
Shields, C. A., and Coauthors. Atmospheric River Tracking Method Intercomparison Project (ARTMIP): Project goals and experimental design. Geosci. Model Dev., 2018, 11, 2455–2474, doi:10.5194/gmd-11-2455-2018.
Stensrud, D. Importance of low-level jets to climate: A review. J. Climate, 1996, 9, 1698–1711.
Stull, R. B. An Introduction to Boundary Layer Meteorology. Kluwer Academic Publishers, 1988, 666 pp.
Su, S. H., J. L. Chu, T. S. Yo, L. Y. Lin. Identification of synoptic weather types over Taiwan area with multiple classifiers. Atmos Sci Lett. 2018, 19:e861. doi:10.1002/asl.861.
Trenberth, K. E., and D. P. Stepaniak. Covariability of components of poleward atmospheric energy transports on seasonal and interannual time-scales. J. Climate, 2003, 16, 3691–3705.
Viale, M., and M. N. Nuñez. Climatology of winter orographic precipitation over the subtropical central Andes and associated synoptic and regional characteristics. J. Hydrometeor., 2001, 12, 481–507. doi:10.1175/2010JHM1284.1.
Wang, B. The Asian Monsoon. Springer Science + Business Media, 2006, Praxis, New York, NY, USA, 787 pp.
Wang, B., and Q. Zhang. Pacific–East Asian teleconnection.: Part II: How the Philippine Sea anomalous anticyclone is established during El Niño development. J. Climate, 2002, 15, 3252–3265. doi:10.1175/1520-0442(2002)015<3252:PEATPI>2.0.CO;2.
Wang, B., R. Wu, and X. Fu. Pacific-East Asian teleconnection: how does ENSO affect East Asian climate? J. Climate, 2000, 13, 1517-1536.
Watanabe, M., and F. F. Jin. Role of Indian Ocean warming in the development of Philippine Sea anticyclone during ENSO. Geophys. Res. Lett., 2002, 29, 1478, doi:10.1029/2001G L.014318.
Wick, G. A., P. J. Neiman, and F. M. Ralph. Description and validation of an automated objective technique for identification and characterization of the integrated water vapor signature of atmospheric rivers. IEEE Trans. Geosci. Remote Sens., 2013, 51, 2166-2176.
Zhang, Z., F. M., Ralph, and M. Zheng. The relationship between extratropical cyclone strength and atmospheric river intensity and position. Geophys. Res. Lett., 2019, 46, 1814–1823. doi.org/10.1029/2018GL079071.
Zhu, Y., and Newell, R. A proposed algorithm for moisture fluxes from atmospheric rivers. Mon.Wea.Rev., 1998, 126, 725–735, doi:10.1175/1520-0493(1998)126%3C0725:APAF MF%3E 2.0.CO;2.