22 4 2017 7 Vol. 22, No. 4 Jul. 2017,. 2017. [J]. 22 (4): 463 472. Zhang Dongling, Lu Xu. 2017. Analysis of abnormal upper circulation over the tropical Indian Ocean in winter [J]. (in Chinese), 22 (4): 463 472, doi: 10.3878/j.issn. 1006-9585. 2016.15011. 1 2 1 100029 2 61741 100094 CEOF 1 (Indian Ocean Dipole, IOD) IOD 3 5 18 22 13 CEOF 1006-9585 2017 04-0463-10 P732.6 A doi:10.3878/j.issn.1006-9585.2016.15011 Analysis of Abnormal Upper Circulation over the Tropical Indian Ocean in Winter ZHANG Dongling 1 and LU Xu 2 1 Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 2 Unit 61741, The Chinese People s Liberation Army, Beijing 100094 Abstract The Complex Empirical Orthogonal Function (CEOF) analysis is applied to discuss the modes and results of abnormal upper circulation over the tropical Indian Ocean in winter. The main conclusions are as follows. The first and second leading modes of the current anomalies are trapped by the equator wave, which decay rapidly poleward from the equator and show a zonal flow pattern. The natures of the first and second modes are the half wave pattern and full wave pattern of the equatorial ocean wave, respectively. This indicates that the equatorial wave anomaly plays an important role in the oceanic flow anomaly. The near-surface sea temperature anomaly resulted from the abnormal vertical motion of the first mode in the winter is different from that in the spring and autumn. In this situation, the distribution of meridional sea temperature anomaly near the equatorial Indian Ocean presents a pattern. It is different from Indian Ocean Dipole (IOD) and is the direct reason for the declining of IOD in winter. The sea temperature anomaly corresponding to the second mode presents a pattern of north negative and south positive. The first mode is closely related to South Asian 2015-01-17 2016-10-03 1974 E-mail: zdl@mail.iap.ac.cn 973 2013CB956203 Funded by National Basic Research Program of China (973 Program, Grant 2013CB956203)
464 22 Vol. 22 winter monsoon anomaly. Both modes demonstrate significant inter-annual and inter-decadal variations. The period of their inter-annual variation is about 3 5 years. The main periods of their inter-decadal variations are about 18 and 22 years, respectively, while they also have a period of about 13 years. The main inter-decadal variations of the first and second modes discussed in this paper correspond to the main inter-decadal variations of the second and first modes of circulation anomaly over the North Pacific and tropical Pacific in winter. Keywords Tropical Indian Ocean, Abnormal circulation, Complex EOF decomposition, South Asian winter monsoon 1 2012 2014 2002 20 Saji et al. (1999) 2009 (Indian Ocean Dipole, IOD) (Hashizume et al. 2012) 2007 IOD IOD IOD Luo et al., 2010; Cai et al., 2012; 2012 2005 2006 2015 5 10 (Complex Empirical Orthogonal Function, CEOF) 2005 2006 IOD 5 2006 IOD 10 2009 IOD 2009 Ha et al., 2012; 2013 CEOF (Pacific Decadal Oscillation, PDO) (North Pacific Gyre Oscillation, NPGO) 2015 2014 CEOF IOD 2 1 Carton and Giese (2008) 1950 2001 52 1 1 112.5 97.5 82.5 67.5 52.5 37.5 22.5 7.5 m 1 25 N 25 S 30 E 120 E 1
4 No. 4 ZHANG Dongling et al. Analysis of Abnormal Upper Circulation over the Tropical Indian Ocean in Winter 465 8 CEOF 22.5 m CEOF 2005 2015 7.5 m 112.5 m 22.5 m 1 1 2 EOF (North et al., 1982) 32.6 13.2 11 33.9 14.0 2005 45.8 3 3.1 1a 5 S 5 N 1 CEOF a b Fig. 1 Spatial pattern of the first leading mode for ocean circulation by complex Empirical Orthogonal Function (CEOF): (a) Surface; (b) subsurface
466 22 Vol. 22 5 S 5 N 1b 0 180 1 0 180 3 2a 1 CEOF 1950 2001 2 CEOF a b Fig. 2 Real time coefficients for the first two leading modes for ocean circulation by CEOF: (a) The first mode; (b) the second mode 3 CEOF a b Fig. 3 (a) Wavelet spectrum and (b) local power spectrum of the time coefficients for the first leading mode for ocean circulation by CEOF
4 No. 4 ZHANG Dongling et al. Analysis of Abnormal Upper Circulation over the Tropical Indian Ocean in Winter 467 3a 3b 3a 3 5 a 18 13 3b 3 5 a 20 60 70 90 18 52 3.2 1 EOF 4 7 S 5 N 7 S 5 N 4a 70 E 5 S 7 S 5 N 55 E 82.5 m 97.5 112.5 m 4 1 Fig. 4 Same as Fig. 1, but for the second mode
468 22 Vol. 22 58 E 95 E 6 S 7 S 4b 0 180 2b CEOF 5a 5b 5a 3 5 a 22 13 5b 3 5 a 20 60 80 21 22 52 4 4.1 (Matsuno, 1966) 82.5 m 1 4.2 2005 2006 6a 5 2005 2006 2015 5 (Sea Surface Temperature Anomaly, SSTA) EOF [ 2012 1a] SSTA 2.5 2.5 2005 IOD IOD 6b Ha et al., 2012 4.3 1 3.1 1a 2013 1 2 1 2 1 1967 10/11 9 800 2 4 800 9/13
4 No. 4 ZHANG Dongling et al. Analysis of Abnormal Upper Circulation over the Tropical Indian Ocean in Winter 469 5 3 Fig. 5 Same as Fig. 3, but for the second mode 6 a b Fig. 6 The near-surface vertical velocity distribution: (a) The first mode; (b) the second mode
470 22 Vol. 22 18 1 Table 1 Time coefficients of the first leading mode in strong South Asia winter monsoon years 1967 1883 1981 372 1968 827 1982 1128 1969 823 1986 778 1977 856 1992 821 1978 1242 1997 2867 1979 1199 2 Table 2 Time coefficients of the first leading mode in weak South Asian winter monsoon years 1960 235 1984 50 1965 762 1988 255 1966 527 1996 535 1970 2305 1998 3811 1971 355 1999 2085 1973-64 2000 1607 1983 168 4.4 18 22 22 PDO 2004 2014 2015 5a PDO 2014 2015 18 3a 5a 13 NPGO 2013 2014 2015 13 NPGO 2014 2015 Walker 1999 5 CEOF 1 1 2 5 IOD 3
4 No. 4 ZHANG Dongling et al. Analysis of Abnormal Upper Circulation over the Tropical Indian Ocean in Winter 471 4 3 5 18 22 13 References Cai W J, van Rensch P, Cowan T, et al. 2012. An asymmetry in the IOD and ENSO teleconnection pathway and its impact on Australian climate [J]. J. Climate, 25 (18): 6318 6329, doi: 10.1175/JCLI-D-11-00501.1.,,. 2002. 5 [J]. ( ), 24 (5): 361 365. Cao Jie, Tao Yun, Duan Xu. 2002. The relation between the May very heavy rainfall in Yunnan and the Asia monsoon index [J]. Journal of Yunan University (Natural Sciences) (in Chinese), 24 (5): 361 365, doi: 10.3321/j.issn: 0258-7971.2002.05.011. Carton J A, Giese B S. 2008. A reanalysis of ocean climate using simple ocean data assimilation (SODA) [J]. Mon. Wea. Rev., 136 (8): 2999 3017, doi: 10.1175/2007MWR1978.1.,. 1999. I. [J]., 23 (1): 101 111. Chen Jun, Sun Shuqing. 1999. Eastern Asian winter monsoon anomaly and variation of global circulation. Part I: A comparison study on strong and weak winter monsoon [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 23 (1): 101 111, doi: 10.3878/j.issn.1006-9895.1999.01.12. Ha K J, Heo K Y, Lee S S, et al. 2012. Variability in the East Asian monsoon: A review [J]. Meteorological Applications, 19 (2): 200 215, doi: 10.1002/met.1320. Hashizume M, Chaves L F, Minakawa N. 2012. Indian Ocean dipole drives malaria resurgence in East African highlands [J]. Scientific Reports, 2: 269, doi: 10.1038/srep00269.,,. 2013. TBO [J]., 29 (1): 1 6. Li Lin, Li Chongyin, Que Zhiping. 2013. Further research on mechanism of TBO in South Asian monsoon region [J]. Journal of Tropical Meteorology (in Chinese), 29 (1): 1 6, doi: 10.3969/j.issn.1004-4965.2013.01.001.,,,. 2013. [J]., 37 (3): 755 764. Liu Ge, Ji Liren, Sun Shuqing, et al. 2013. A discussion on the East Asian winter monsoon index Differences between the East Asian winter monsoon at mid-high and low latitudes [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 37 (3): 755 764, doi: 10.3878/j.issn.1006-9895.2012.12054.,,. 2014. EOF [J]., 31 (2): 56 66. Lu Xu, Bao Yun, Lü Qingping. 2014. CEOF analysis for upper current of tropic Pacific Ocean [J]. Marine Forecasts (in Chinese), 31 (2): 56 66, doi: 10.11737/j.issn.1003-0239.2014.02.009. Luo J J, Zhang R C, Behera S K, et al. 2010. Interaction between El Niño and extreme Indian Ocean Dipole [J]. J. Climate, 23 (3): 726 742, doi: 10.1175/2009JCLI3104.1.,,. 2013. NPGO [J]., 18 (2): 210 220. Lü Qingping, Lu Kaicheng, Zhang Ming. 2013. NPGO mode of the upper sea temperature anomalies in the North Pacific during winter [J]. Climatic and Environmental Research (in Chinese), 18 (2): 210 220, doi: 10.3878/j.issn.1006-9585. 2012.11156.,,,. 2015. PDO NPGO [J]., 33 (2): 1 7. Lü Qingping, Lu Xu, Zhu Juan, et al. 2015. Relationship between the main modes of circulation anomalies and the PDO, NPGO modes in the North Pacific during winter [J]. Journal of Marine Sciences (in Chinese), 33 (2): 1 7, doi: 10.3969/j.issn.1001-909X.2015.02.001. Matsuno T. 1966. Quasi-geostrophic motions in the equatorial area [J]. J. Meteor. Soc. Japan, 44 (1): 25 43. North G R, Bell T L, Cahalan R F, et al. 1982. Sampling errors in the estimation of empirical orthogonal functions [J]. Mon. Wea. Rev., 110 (7): 699 706, doi: 10.1175/1520-0493(1982)110<0699:SEITEO>2.0.CO;2.. 2012. [J]., 17 (3): 327 338. Peng Jingbei. 2012. Influence of the sea surface temperature in the eastern Indian Ocean on the wintertime rainfall in the southern part of China [J]. (in Chinese), 17 (3): 327 338, doi: 10.3878/j.issn.1006-9585.2011.10139. Saji N H, Goswami B N, Vinayachandran P N, et al. 1999. A dipole mode in the tropical Indian Ocean [J]. Nature, 401 (6751): 360 363.,,. 2009. [J]., 25 (5): 621 627. Xiao Ying, Zhang Zuqiang, He Jinhai. 2009. Progresses in the studies on Indian Ocean dipoles [J]. Journal of Tropical Meteorology (in Chinese), 25 (5): 621 627, doi: 10.3969/j.issn.1004-4965.2009.05.014.,. 2012. [J]., 36 (5): 879 888. Xu Zhiqing, Fan Ke. 2012. Possible process for influences of winter and spring Indian Ocean SST anomalies interannual variability mode on summer rainfall over Eastern China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 36 (5): 879 888, doi: 10.3878/j.issn.1006-9895.2012.11176.,. 2014. [J]., 19 (1): 31 40. Xu Zhiqing, Fan Ke. 2014. Simulating the mechanism of the interannual variability mode of the Indian Ocean Sea surface temperature anomalies impacting on the summer rainfall over Eastern China [J]. Climatic and Environmental Research (in Chinese), 19 (1): 31 40, doi: 10.3878/j.issn. 1006-9585.2012.12114.,. 2007. [J]., 31 (1): 64 76. Yan Hongming, Li Chongyin. 2007. A study of the sea surface temperature zonal gradient mode in the equatorial Indian
472 22 Vol. 22 Ocean and its influence on climate [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 31 (1): 64 76, doi: 10.3878/j.issn.1006-9895. 2007.01.07.,,,. 2004. [J]., 28 (6): 979 992. Yang Xiuqun, Zhu Yimin, Xie Qian, et al. 2004. Advances in studies of Pacific decadal oscillation [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 28 (6): 979 992, doi: 10.3878/j.issn.1006-9895.2004.06.15.,. 2005. [J]., 10 (3): 387 400. Zhang Dongling, He Juanxiong. 2005. Dynamic statistic diagnosis of upper current in tropical Indian Ocean [J]. (in Chinese), 10 (3): 387 400, doi: 10.3878/j.issn.1006-9585.2005.03.12.. 2006. [D]., 286 292. Zhang Dongling. 2006. Dynamic statistic analysis of space structure and time evolution in Asian summer monsoon [D]. Ph. D. dissertation (in Chinese), Institute of Atmospheric Physics, Chinese Academy of Sciences, 286 292.,,. 2015. [J]., 39 (4): 692 704. Zhang Dongling, Lü Qingping, Zhang Lifeng. 2015. Dynamical statistic analysis of decadal anomalies of air sea circulation in the North Pacific during winter [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 39 (4): 692 704, doi: 10.3878/j.issn.1006-9895.1501.14132.