A preliminary analysis of the characteristics and mechanisms for the recurrence of wintertime SST anomalies in the southern Indian Ocean
-
摘要: 本文主要利用1958–2016年GECCO2等资料通过超前/滞后相关分析方法，分析了南印度洋海表温度距平（SSTA）冬季−冬季重现的时空特征，并探讨了海洋和大气强迫对其形成的贡献。结果显示，SSTA冬季−冬季重现主要发生在南印度洋15ºS以南海域，特别是在马达加斯加岛至澳大利亚西南部之间的海域（15º～45ºS，70º～100ºE）重现信号最为显著。重现信号除了主要发生在次年冬季外，在部分海域重现信号发生较早，可在次年秋季发生并持续至随后的冬季。进一步分析表明，混合层深度冬深夏浅的变化（即海洋重现机制）是研究海域SSTA冬季重现的主因。另外，在马达加斯加岛南部海域和澳大利亚西南部海域海面净热通量对SSTA的重现也有直接的贡献。Abstract: This study mainly uses the GECCO2 reanalysis data from 1958 to 2016 to analyze the spatiotemporal characteristics of the southern Indian Ocean sea surface temperature anomalies (SSTA) winter-to-winter recurrence through lag correlation analysis, and investigate the roles of oceanic reemergence mechanism and atmospheric forcing. The results show that the winter-to-winter recurrence of SSTA occurs south of 15ºS in the southern Indian Ocean, especially between Madagascar and southwestern Australia (15º–45ºS, 70º–100ºE). The recurrence mainly occurs in the winter of the following year, but there are also some areas where the recurrence occurs in the following fall and continue to the subsequent winter. Further analysis shows that the difference between the deep winter mixed layer and shallow summer mixed layer, known as the oceanic reemergence mechanism, is the main cause of the recurrence of SSTA in the southern Indian Ocean. In addition, the net heat flux also directly contributes to the recurrence of SSTA in southern Madagascar and southwestern Australia.
-
图 1 南印度洋内A点(30.5ºS，100.5ºE) 的8月SSTA与同年8月[8月(0)]至次年12月[12月(+1)]SSTA之间的滞后相关系数曲线
粉色虚线代表95%的置信水平
Fig. 1 Lag correlations between the monthly sea surface temperature anomalies (SSTA) in August and the monthly SSTA from August of the current year [August (0)] to December of the following year [December (+1)] at the grid point A (30.5ºS，100.5ºE) in the southern Indian Ocean (SIO)
The pink dashed line indicates the 95% confidence level
图 2 由GECCO2得到的南印度洋8月与次年8月（即滞后12个月）的SSTA自相关系数的空间分布(a)，8月与次年2月（即滞后6个月）的SSTA自相关系数的空间分布(b)，SSTA 冬季重现的空间分布(c)。d–f、g–i、j–l分别同a–c，但来自ORAS4、HadiSST、OAFlux数据集
黑色实线代表95%置信水平。c和f中红色等值线分别为由GECCO2和ORAS4计算得到的8月与2月气候态月平均混合层深度比值，数值即为比值的大小，蓝色实心点代表符合SSTA冬季重现标准的网格点
Fig. 2 Spatial distribution of SSTA autocorrelation between August and August of the following year (12-month lag autocorrelation) (a), SSTA autocorrelation between August and February of the following year (6-month lag autocorrelation) (b), and SSTA winter-to-winter recurrence in the southern Iindian Ocean (c) from GECCO2. d–f, g–i, and j–l are the same as a–c, but come from ORAS4, HadiSST and OAFlux respectively
The thin solid black lines indicate the 95% confidence level. The red contours in c and f represent the ratio of climatological mixed layer depth (MLD) in August and MLD in February computed from GECCO2 and ORAS4, respectively, and the number is the magnitude of the ratio. The blue dots represent the grid points that meet the definition of SSTA winter-to-winter recurrence
图 3 由GECCO2计算得到的8月[8月(0)] SSTA与同年8月[8月(0)]至次年12月[12月(+1)] SSTA之间的滞后相关系数的纬向分布(a)，经度平均范围为70º~100ºE。b、c、d同a，但分别由ORAS4、HadiSST、OAFlux计算得到
黑实线代表95%的置信水平
Fig. 3 Lag correlations between SSTA for August and monthly SSTA from the August of the current year [August (0)] through December of the following year [December (+1)] for the longitudinal average between 70ºE and 100ºE computed from GECCO2 (a), ORAS4 (b), HadiSST (c), and OAFlux (d)
The thin solid black line indicates the 95% confidence level
图 4 使用GECCO2计算得到的南印度洋8月气候态混合层深度（a），2月气候态混合层深度（c），8月与2月气候态月平均混合层深度比值的水平分布（e）。b、d、f分别同a、c、e，但来自ORAS4
e中黑色实心点代表符合SSTA冬季重现标准的网格点，紫色、黑色、红色方框分别为区域A、B、C
Fig. 4 Climatological mixed layer depth in August(a), climatological mixed layer depth in February (c), the ratio of climatological mixed layer depth in August and mixed layer depth in February (e) computed from GECCO2. b, d, and f are the same as a, c, and e respectively, but come from ORAS4
The black dots in e represent the grid points that meet the definition of SSTA winter-to-winter recurrence, and the purple, black and red box are regions A, B and C respectively
图 5 南印度洋SSTA冬季重现与混合层季节变化的关系
a.区域A的8月SSTA与同年8月[8月(0)]至次年12月[12月(+1)]SSTA之间的滞后相关系数曲线，粉色虚线表示95%的置信水平；c、e与a相同，但分别为区域B、C。b. 区域A的8月SSTA与同年8月[8月(0)]至次年12月[12月(+1)]的海表至300 m深度的温度异常的滞后相关系数的垂向分布。白色虚线表示95%的置信水平，白色实线代表气候态月平均混合层深度；d、f同b，但分别为区域B、C。区域A至区域C的地理位置见图4e
Fig. 5 The relationship between SSTA winter-to-winter recurrence and seasonal variability of mixed layer depth in the southern Indian Ocean
a. Lag correlation coefficients between SSTA in August and SSTA from August of the current year [August (0)] to November of the following year [November (+1)] in the Region A, and the pink dashed line indicates the 95% confidence level; c and e are the same as a, but for the regions B and C respectively. b. Vertical distribution of lag correlation coefficients for SSTA in August of the current year [August (0)] to the temperature anomalies from the surface to 300 m from the current year August to December of the following year [December (+1)] in the Region A. Solid white line represents the climatological mixed layer depth,significant value at the 95% confidence level is shown by the white dashed line; d and f are the same as b, but for the regions B and C respectively. Regions A, B and C are shown in fig. 4e
图 6 根据NCEP资料计算的8月与次年8月（即滞后12个月）的海面净热通量异常自相关系数的空间分布（a），8月与次年8月（即滞后12个月）的海面净热通量异常自相关系数和8月与次年2月（即滞后6个月）的净热通量异常自相关系数的差值的空间分布（b），8月海面净热通量异常与同年8月SSTA的相关系数的空间分布（c）和8月海面净热通量异常与次年8月SSTA的滞后相关系数的空间分布（d）
a中黑色实心点代表符合SSTA冬季重现标准的网格点，红色和蓝色方框分别为区域D和E，黑色实线代表95%的置信水平
Fig. 6 Spatial distribution of net heat flux anomalies (NHFA) autocorrelation between August and August of the following year (12-month lag autocorrelation) (a), the difference between NHFA autocorrelation between August and August of the following year (12-month lag autocorrelation) and NHFA autocorrelation between August and February of the following year (6-month lag autocorrelation) (b), correlation coefficients between NHFA in August and GECCO2 SSTA in August of the current year (c), and lag correlation coefficients between NHFA in August and GECCO2 SSTA in August of the following year (d) derived from NCEP data
The black dots in a represent the grid points that meet the definition of SSTA winter-to-winter recurrence, and the red and blue box are regions D and E respectively. The thin solid black lines indicate the 95% confidence level
图 7 使用GECCO2海温与大气数据以及NCEP大气数据计算得到的区域D（a）和区域E（b）的8月SSTA与同年8月[8月(0)]至次年12月[12月(+1)]的SSTA滞后相关系数（红色实线），冬季混合层底部深度处温度异常滞后相关系数（蓝色实线，a中为75 m，b中为172 m），以及海面净热通量异常（NHFA）滞后相关系数（GECCO2为绿色实线，NCEP为黑色实线）
粉色虚线代表95%的置信水平，区域D和E的位置见图6a
Fig. 7 Lag correlation of August anomalies of temperature at surface (red solid line) and at depth corresponding to the bottom of the climatological winter mixed layer depth (blue solid line, 75 m in a and 172 m in b) from GECCO2, net het flux anomalies from GECCO2 (green solid line) and NCEP (black solid line) in the Region D (a) and Region E (b)
The pink dashed line indicates the 95% confidence level. Regions D and E are shown in Fig. 6a
图 8 使用NCEP大气数据计算得到的区域E的8月与同年8月[8月(0)]至次年12月[12月(+1)]的潜热通量滞后相关系数（红色实线），感热通量滞后相关系数（绿色实线），短波辐射滞后相关系数（蓝色实线），以及海表风速滞后相关系数（黑色实线）
粉色虚线代表95%的置信水平，区域E的位置见图6a
Fig. 8 Lag correlation of August latent heat flux (red solid line), sensible heat flux (green solid line), short wave radiation (blue solid line), and surface wind speed (black solid line) in the Region E computed from NCEP
The pink dashed line indicates the 95% confidence level. Regions D and E are shown in Fig. 6a
图 9 根据NCEP资料计算的8月与次年8月（即滞后12个月）的潜热通量自相关系数的空间分布(a)，感热通量自相关系数的空间分布(b)，短波辐射自相关系数的空间分布(c)，以及海表风速自相关系数的空间分布(d)
图中黑色实线代表95%的置信水平
Fig. 9 Spatial distribution of latent heat flux autocorrelation between August and August of the following year (12-month lag autocorrelation) (a), sensible heat flux autocorrelation between August and August of the following year (b), short wave radiation autocorrelation between August and August of the following year (c), and surface wind speed autocorrelation between August and August of the following year (d) derived from NCEP data
The thin solid black lines indicate the 95% confidence level
-
[1] Liu Zhengyu, Liu Yun, Wu Lixin, et al. Seasonal and long-term atmospheric responses to reemerging north Pacific Ocean variability: a combined dynamical and statistical assessment[J]. Journal of Climate, 2007, 20(6): 955−980. doi: 10.1175/JCLI4041.1 [2] Gastineau G, Frankignoul C. Influence of the North Atlantic SST variability on the atmospheric circulation during the twentieth century[J]. Journal of Climate, 2015, 28(4): 1396−1416. doi: 10.1175/JCLI-D-14-00424.1 [3] 赵霞, 杨光. IPCC耦合模式对北太平洋海–气系统冬季重现的模拟[J]. 海洋学报, 2019, 41(9): 114−125.Zhao Xia, Yang Guang. The winter-to-winter recurrence in the North Pacific air-sea system: IPCC-AR4 model evaluation[J]. Haiyang Xuebao, 2019, 41(9): 114−125. [4] Rodwell M J, Folland C K. Atlantic air-sea interaction and seasonal predictability[J]. Quarterly Journal of the Royal Meteorological Society, 2002, 128(583): 1413−1443. doi: 10.1002/qj.200212858302 [5] Folland C K, Scaife A A, Lindesay J, et al. How potentially predictable is northern European winter climate a season ahead?[J]. International Journal of Climatology, 2012, 32(6): 801−818. doi: 10.1002/joc.2314 [6] Namias J, Born R M. Temporal coherence in North Pacific sea-surface temperature patterns[J]. Journal of Geophysical Research, 1970, 75(30): 5952−5955. doi: 10.1029/JC075i030p05952 [7] Namias J, Born R M. Further studies of temporal coherence in North Pacific sea surface temperatures[J]. Journal of Geophysical Research, 1974, 79(6): 797−798. doi: 10.1029/JC079i006p00797 [8] Alexander M A, Deser C. A mechanism for the recurrence of wintertime midlatitude SST anomalies[J]. Journal of Physical Oceanography, 1995, 25(1): 122−137. doi: 10.1175/1520-0485(1995)025<0122:AMFTRO>2.0.CO;2 [9] Zhao Xia, Li Jianping. Winter-to-winter recurrence and non-winter-to-winter recurrence of SST anomalies in the central North Pacific[J]. Journal of Geophysical Research, 2012, 117(C5): C05027. [10] Hanawa K, Sugimoto S. ‘Reemergence’ areas of winter sea surface temperature anomalies in the world’s oceans[J]. Geophysical Research Letters, 2004, 31(10): L10303. [11] Alexander M A, Deser C, Timlin M S. The reemergence of SST anomalies in the North Pacific Ocean[J]. Journal of Climate, 1999, 12(8): 2419−2433. doi: 10.1175/1520-0442(1999)012<2419:TROSAI>2.0.CO;2 [12] Alexander M A, Timlin M S, Scott J D. Winter-to-winter recurrence of sea surface temperature, salinity and mixed layer depth anomalies[J]. Progress in Oceanography, 2001, 49(1/4): 41−61. [13] Sugimoto S, Hanawa K. Remote reemergence areas of winter sea surface temperature anomalies in the North Pacific[J]. Geophysical Research Letters, 2005, 32(1): L01606. [14] Zhao Xia, Li Jianping. Winter-to-winter recurrence of sea surface temperature anomalies in the Northern Hemisphere[J]. Journal of Climate, 2010, 23(14): 3835−3854. doi: 10.1175/2009JCLI2583.1 [15] Ciasto L M, Thompson D W J. Observational evidence of reemergence in the extratropical Southern Hemisphere[J]. Journal of Climate, 2009, 22(6): 1446−1453. doi: 10.1175/2008JCLI2545.1 [16] Taws S L, Marsh R, Wells N C, et al. Re-emerging ocean temperature anomalies in late-2010 associated with a repeat negative NAO[J]. Geophysical Research Letters, 2011, 38(20): L20601. [17] Timlin M S, Alexander M A, Deser C. On the reemergence of North Atlantic SST anomalies[J]. Journal of Climate, 2002, 15(18): 2707−2712. doi: 10.1175/1520-0442(2002)015<2707:OTRONA>2.0.CO;2 [18] de Coëtlogon G, Frankignoul C. The persistence of winter sea surface temperature in the North Atlantic[J]. Journal of Climate, 2003, 16(9): 1364−1377. doi: 10.1175/1520-0442(2003)16<1364:TPOWSS>2.0.CO;2 [19] Byju P, Dommenget D, Alexander M A. Widespread reemergence of sea surface temperature anomalies in the global oceans, including tropical regions forced by reemerging winds[J]. Geophysical Research Letters, 2018, 45(15): 7683−7691. doi: 10.1029/2018GL079137 [20] Balmaseda M A, Mogensen K, Weaver A T. Evaluation of the ECMWF ocean reanalysis system ORAS4[J]. Quarterly Journal of the Royal Meteorological Society, 2013, 139(674): 1132−1161. doi: 10.1002/qj.2063 [21] Rayner N A, Parker D E, Horton E B, et al. Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century[J]. Journal of Geophysical Research, 2003, 108(D14): 4407. doi: 10.1029/2002JD002670 [22] Yu Lisan, Weller R A. Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005)[J]. Bulletin of the American Meteorological Society, 2007, 88(4): 527−540. doi: 10.1175/BAMS-88-4-527 [23] de Boyer Montégut C, Madec G, Fischer A S, et al. Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology[J]. Journal of Geophysical Research, 2004, 109(C12): C12003. doi: 10.1029/2004JC002378 [24] Kalnay E, Kanamitsu M, Kistler R, et al. The NCEP/NCAR 40-year reanalysis project[J]. Bulletin of the American Meteorological Society, 1996, 77(3): 437−472. doi: 10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2 [25] Namias J, Yuan Xiaojun, Cayan D R. Persistence of North Pacific sea surface temperature and atmospheric flow patterns[J]. Journal of Climate, 1988, 1(7): 682−703. doi: 10.1175/1520-0442(1988)001<0682:PONPSS>2.0.CO;2 [26] Nardelli B B, Guinehut S, Verbrugge N, et al. Southern Ocean mixed-layer seasonal and interannual variations from combined satellite and in situ data[J]. Journal of Geophysical Research, 2017, 122(12): 10042−10060. doi: 10.1002/2017JC013314 [27] Rao R R, Molinari R L, Festa J F. Evolution of the climatological near-surface thermal structure of the tropical Indian Ocean: 1. Description of mean monthly mixed layer depth, and sea surface temperature, surface current, and surface meteorological fields[J]. Journal of Geophysical Research, 1989, 94(C8): 10801−10815. doi: 10.1029/JC094iC08p10801 [28] Schiller A, Oke P R. Dynamics of ocean surface mixed layer variability in the Indian Ocean[J]. Journal of Geophysical Research, 2015, 120(6): 4162−4186. doi: 10.1002/2014JC010538 -
下载:
计量
- 文章访问数: 415
- HTML全文浏览量: 171
- PDF下载量: 54
- 被引次数: 0
