Multiscale Analysis of Interannual Variability of Summer Precipitation over Middle and Lower Reaches of Yangtze River
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摘要: 基于中国气象局（CMA）提供的降水站点观测数据和ECMWF提供的ERA5再分析数据集，通过尺度分离方法，对降水率进行定量诊断，探究了长江中下游地区1980—2020年夏季降水年际差异形成的多尺度特征。结果表明该区域降水呈现显著的天气尺度（小于10天）和次季节主导周期（10~30天以及30~60天）。通过定量诊断背景尺度（大于60天）、季节内尺度（30~60天）、准双周尺度（10~30天）和天气尺度（小于10天）变量之间的相互作用，发现长江中下游地区夏季降水主要决定于背景水汽、背景风和天气尺度风，并且降水强年背景环流贡献最大，降水弱年天气尺度扰动贡献更大。针对长江中下游地区的两个降水大值中心进行了进一步的分析，发现长江中游平均降水更多依赖于天气尺度扰动，下游降水更多依赖于背景环流。在长江中游降水强年，西北太平洋副热带高压更加西伸，且强度更强。在次季节尺度两个降水大值中心也存在较大差异，下游地区30~60天振荡更为显著，尤其表现在降水偏强年份。Abstract: Based on observational data from meteorological stations of the China Meteorological Administration and the ERA5 reanalysis dataset provided by the European Centre for Medium-Range Weather Forecasts, this study conducted a quantitative diagnosis of precipitation rates using the scale separation method to explore the multi-scale characteristics of interannual variability of summer precipitation in the middle and lower reaches of the Yangtze River from 1980 to 2020. The results indicate that the precipitation variability in the region exhibited two dominant timescales, one with a synoptic period (less than 10 days) and the other with a subseasonal period (10-30 days and 30-60 days). By quantitatively diagnosing the interactions between background-scale (greater than 60 days), intraseasonal scale (30-60 days), quasi-biweekly-scale (10-30 days), and synoptic-scale (less than 10 days) variables, we found that summer precipitation in the middle and lower reaches of the Yangtze River was mainly determined by ambient water vapor, ambient wind, and synoptic-scale wind. Moreover, background circulation contributed the most in years with strong precipitation, while synoptic-scale disturbances contributed more in years with weak precipitation. Further analysis of the two precipitation centers in the middle and lower reaches of the Yangtze River reveals that the average precipitation in the middle reaches was more dependent on synoptic-scale disturbances. In comparison, precipitation in the lower reaches was more dependent on background circulation. In years with strong precipitation in the middle reaches, the subtropical high in the Northwestern Pacific extended further westward and exhibited stronger intensity. There was also a significant difference between the two precipitation centers at the subseasonal scale, with the 30-60-day oscillation being more significant in the downstream areas, especially in years with stronger precipitation.
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图 1 1980—2020年台站观测降水量(阴影，单位：mm·d-1)及其标准差(等值线，单位：mm·d-1)（a）；台站观测降水的逐年标准化距平（b）；研究区域夏季逐日降水的功率谱分析（其中黑色实线：功率谱值密度值；虚线：95%马尔可夫红噪声置信水平检验）（c）
图 2 降水偏多年和偏少年不同尺度逐日降水标准差的差值
（a）>60天的背景尺度；（b）30~60天尺度；（c）10~30天尺度；（d）＜10天的天气尺度。单位：mm·d-1；打点区域通过95%显著性T检验。
图 3 1980—2020年夏季整层水汽通量辐合（阴影，单位：mm·d-1）以及标准差（等值线，单位：mm·d-1）（a）；1980—2020年台站观测日平均降水量（实线）和整层水汽通量辐合（虚线）随时间的演变（单位：mm·d-1，右上角为两者时间序列的相关系数）（b）；1980—2020年夏季整层水汽通量辐合各项日平均值（单位：mm·d-1）（c）；降水偏多年（黑色），降水偏少年（浅灰色）以及偏多年与偏少年之差（深灰色）的整层水汽通量辐合各项日平均值（单位：mm·d-1）（d）
c，d中横坐标表示公式3中的各项；（e，f）整层积分的纬向水汽通量辐合（黑色）及经向水汽通量辐合（浅灰色，单位：mm·d-1），其中图e为背景风与背景水汽的结果，f为天气尺度风和背景水汽的结果。
图 4 850 hPa背景比湿q（阴影，单位：g·kg-1，打点区域为通过95%显著性T检验）和背景风场v (矢量，单位：m·s-1，红色箭头为通过95%显著性T检验，黑色箭头未通过)的异常空间分布
紫色方框代表长江中下游地区。（a）降水偏多年；（b）降水偏少年；（c）差值；（d）850 hPa平均动能与天气尺度扰动动能之差（单位: m2·s-2）。
图 5 长江中游地区（a）和下游地区（b）夏季逐日降水的功率谱分析（其中黑色实线：功率谱密度；虚线：95%马尔可夫红噪声置信水平检验）以及中游地区（c）和下游地区（d）夏季降水逐年标准化距平。
图 6 长江中游地区（a）和下游地区（c）整层水汽通量辐合各项贡献（单位：mm·d-1）以及异常年份长江中游地区（b）和下游地区（d）的整层水汽通量辐合各项贡献（单位：mm·d-1，黑色柱状为降水偏多年，灰色柱状为降水偏少年）。
图 7 850 hPa背景比湿q（阴影，打点区域通过95%显著性T检验, 单位：g·kg-1）和背景风场v（矢量，单位：m·s-1，红色箭头通过95%显著性T检验，黑色未通过）的异常以及588 gpm等值线（黑色粗实线）空间分布
紫色方框代表长江中下游地区，黑色方框代表两个降水关键区。a. 长江中游地区降水偏多年；b. 长江下游地区降水偏多年；c. 降水偏多年中游与下游之差；d. 长江中游地区降水偏少年；e. 长江下游地区降水偏少年；f. 降水偏少年中游与下游之差。
图 8 1980年（a）和1999年（b）夏季平均降水量(阴影，单位：mm·d-1)及其异常(等值线，单位：mm·d-1)以及长江中游地区1980年（c）和长江下游地区1999年（d）不同尺度降水时间演变（蓝色：>60天，红色：30~60天，紫色：10~30天，柱状：实际降水量，单位：mm·d-1）
左侧坐标轴为不同尺度降水异常，右侧坐标轴表示实际降水量。
表 1 两个区域降水异常年份
区域 降水偏多年 降水偏少年 长江中游 1980、1983、1998、2016、2020 1985、1992、1994、2001、2006、2014、2019 长江下游 1980、1983、1996、1999、2016、2016、2020 1985、1988、2005、2006、2019 
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[1] 叶笃正, 黄荣辉. 我国长江黄河两流域旱涝规律成因与预测研究的进展、成果与问题[J]. 地球科学进展, 1991, 6(4): 24. [2] 琚建华, 赵尔旭. 东亚夏季风区的低频振荡对长江中下游旱涝的影响[J]. 热带气象学报, 2005, 21(2): 163-171. [3] 黄荣辉. 我国重大气候灾害的形成机理和预测理论研究[J]. 地球科学进展, 2006, 21(6) : 564-575. [4] 吴志伟, 李建平, 何金海, 等. 大尺度大气环流异常与长江中下游夏季长周期旱涝急转[J]. 科学通报, 2006(14): 1 717-1 724. [5] DING Y. The variability of the Asian summer monsoon[J]. J Meteoto Soc Japan, 2007, 85B: 21-54. [6] ZHANG Z, SUN X, YANG X Q. Understanding the interdecadal variability of East Asian summer monsoon precipitation: Joint influence of three oceanic signals[J]. J Climate, 2018, 31(14): 5 485-5 506. [7] 龚道溢, 朱锦红, 王绍武. 长江流域夏季降水与前期北极涛动的显著相关[J]. 科学通报, 2002, 47(7): 546-549. [8] NAN S, LI J. The relationship between the summer precipitation in the Yangtze River valley and the boreal spring Southern Hemisphere annular mode[J]. Geophys Res Lett, 2003, 30(24): 2 266. [9] JU JH, LV JM, CAO J, et al. Possible impacts of the Arctic Oscillation on the interdecadal variation of summer monsoon rainfall in East Asia [J]. Adv Atmos Sci, 2005, 22: 39-48. [10] 尹志聪, 王亚非, 袁东敏. 梅雨准双周振荡的年际变化及其前期强信号分析[J]. 大气科学学报, 2011, 34(3): 297-304. [11] LU R. Interannual variability of the summertime North Pacific subtropical high and its relation to atmospheric convection over the warm pool[J]. J Meteor Soc Japan, 2001, 79(3): 771-783. [12] 张顺利, 陶诗言, 张庆云, 等. 长江中下游致洪暴雨的多尺度条件[J]. 科学通报, 2002, 47(6): 467-473. [13] CHEN Y, ZHAI P. Precursor circulation features for persistent extreme precipitation in central-eastern China[J]. Wea Forecasting, 2014, 29 (2): 226-240. [14] CHEN Y, ZHAI P. Two types of typical circulation pattern for persistent extreme precipitation in Central-Eastern China[J]. Quart J Roy Meteor Soc, 2014, 140(682): 1 467-1 478. [15] LI H, HE S, FAN K, et al. Relationship between the onset date of the Meiyu and the South Asian anticyclone in April and the related mechanisms[J]. Climate Dyn, 2019, 52: 209-226. [16] XUE F, WANG H, HE J. Interannual variability of Mascarene high and Australian high and their influences on summer rainfall over East Asia[J]. Chinese Science Bulletin, 2003, 48: 492-497. [17] YUAN Y, GAO H, LI W, et al. The 2016 summer floods in China and associated physical mechanisms: A comparison with 1998[J]. J Meteor Res, 2017, 31(2): 261-277. [18] TAO S Y. A review of recent research on the East Asian summer monsoon in China[J]. Monsoon Meteorology, 1987: 60-92. [19] DING Y H, LI C Y, LIU Y J. Overview of the South China Sea monsoon experiment[J]. Adv Atmos Sci, 2004, 21: 343-360. [20] SIMMONDS I, BI D, HOPE P. Atmospheric water vapor flux and its association with rainfall overchina in summer[J]. J Climate, 1999, 12 (5): 1 353-1 367. [21] JIANG Z, YANG S, HE J, et al. Interdecadal variations of East Asian summer monsoon northward propagation and influences on summer precipitation over East China[J]. Meteor Atmos Phys, 2008, 100: 101-119. [22] WANG N, ZENG X M, GUO W D, et al. Quantitative diagnosis of moisture sources and transport pathways for summer precipitation over the mid-lower Yangtze River Basin[J]. J Hydrol, 2018, 559: 252-265. [23] LAU K M, YANG G J, SHEN S H. Seasonal and intraseasonal climatology of summer monsoon rainfall over East Asia[J]. Mon Wea Rev, 1988, 116(1): 18-37. [24] 毛江玉, 吴国雄. 1991年江淮梅雨与副热带高压的低频振荡[J]. 气象学报, 2005, 63 (5): 762-770. [25] 王遵娅, 丁一汇. 中国雨季的气候学特征[J]. 大气科学, 2008, 32 (1): 1-13. [26] YAO S, HUANG Q, ZHANG Y, et al. A study on response of precipitation in China to monsoon intraseasonal oscillation[J]. J Trop Meteor, 2012, 18(4): 503-511. [27] MAO J, WU G. Intraseasonal variations of the Yangtze rainfall and its related atmospheric circulation features during the 1991 summer[J]. Climate Dyn, 2006, 27: 815-830. [28] ZHU C, NAKAZAWA T, LI J, et al. The 30-60 day intraseasonal oscillation over the western North Pacific Ocean and its impacts on summer flooding in China during 1998[J]. Geophys Res Lett, 2003, 30(18): 1 952. [29] WANG Y, SEN O L, WANG B. A highly resolved regional climate model (IPRC-RegCM) and its simulation of the 1998 severe precipitation event over China. Part Ⅰ: Model description and verification of simulation[J]. J Climate, 2003, 16(11): 1 721-1 738. [30] LIU H, ZHANG D L, WANG B. Daily to submonthly weather and climate characteristics of the summer 1998 extreme rainfall over the Yangtze River Basin[J]. J Geophy Res: Atmos, 2008, 113(D22): 101. [31] YANG Q M. The 20-30-day oscillation of the global circulation and heavy precipitation over the lower reaches of the Yangtze River valley [J]. Science in China Series D: Earth Sciences, 2009, 52(10): 1 485. [32] 杨莲梅, 张庆云. 夏季东亚西风急流Rossby波扰动异常与中国降水[J]. 大气科学, 2007, 31(4): 586-595. [33] 黄海燕, 王亚非, 何金海, 等. 天气尺度波列对长江中下游6月梅雨的影响[J]. 大气科学学报, 2016, 39(1): 28-36. [34] DING L, LI T, SUN Y. Subseasonal and synoptic variabilities of precipitation over the Yangtze River basin in the summer of 2020[J]. Adv Atmos Sci, 2021, 38: 2 108-2 124. [35] BRIGHAM E O, MORROW R E. The fast Fourier transform[J]. IEEE Spectrum, 1967, 4(12): 63-70. [36] DEE D P, UPPALA S M, SIMMONS A J, et al. The ERA‐Interim reanalysis: Configuration and performance of the data assimilation system [J]. Quart J Roy Meteor Soc, 2011, 137(656): 553-597. [37] YAO S, TONG Q, LI T, et al. The 10-30‐day oscillation of winter rainfall in southern China and its relationship with circulation patterns in different latitudes[J]. In J Climatol, 2020, 40(6): 3 268-3 280. [38] KIKUCHI K, Wang B. Spatiotemporal wavelet transform and the multiscale behavior of the Madden-Julian oscillation[J]. J Climate, 2010, 23(14): 3 814-3 834. [39] HSU P C, LI T. Interactions between boreal summer intraseasonal oscillations and synoptic-scale disturbances over the western North Pacific. Part Ⅱ: Apparent heat and moisture sources and eddy momentum transport[J]. J Climate, 2011, 24(3): 942-961. [40] 许乐心, 张人禾, 齐艳军. 长江中游和下游夏季降水季节内振荡的差异[J]. 大气科学, 2017, 41(6): 1 125-1 140. -
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