长江中下游城市内涝与雨季污染协同治理对策

针对长江中下游城市内涝与雨季污染协同治理的突出问题,对城市水安全、雨季水体返黑返臭风险和河湖水生态退化三方面存在的问题进行了论述。发现长江中下游城市河网密度高、降水量大、暴雨多发,同时人口密集、经济发展水平高,内涝、污染、生态退化等水问题突出;城市内涝频发,雨季污染造成某些城市水体局部返黑返臭,严重影响城市水环境品质,成为制约长江中下游城市绿色发展的重要瓶颈问题。提出了建立三级内涝协同防治体系、构建城市“绿-灰-蓝”设施耦合工程体系、协同推进水体品质提升与生态修复等建议。

1991—2020年雅安市雨季的气候特征分析

利用1991—2020年雅安市8个国家地面气象观测站逐日降水数据,依托气象行业标准《中国雨季监测指标西南雨季》(QX/T 396—2017),对雅安雨季气候特征进行统计分析。结果表明:雅安雨季大多开始于4月下旬至5月上旬,结束于10月上旬至中旬,雨季降水量占全年总降水量的80%左右。就多年气候雨季而言,雅安平均雨季初日为5月5日,平均雨季终日为10月11日,持续159d,雨季平均降水量为985.4mm。从变化趋势来看,1991—2010年雅安雨季持续时间总体呈下降趋势,2010年后总体呈上升趋势,雨季降水强度总体波动保持相对稳定。

青藏高原雨季特征量的气候特征及其南北差异

利用1980~2019年青藏高原101个气象观测站的逐日降水量和气温数据,参考《中国雨季监测指标》,计算了雨季特征量(包括雨季开始期、结束期、持续时间、降水量和降水强度),分析了青藏高原雨季特征量的气候特征,并讨论了雨季特征量的区域差异。结果表明:(1)青藏高原雨季开始期最早(晚)为5月2日(6月19日),由高原东部向西部逐渐推进;结束期最早(晚)为9月15日(10月20日),由高原西部向东部快速结束;青藏高原东部(西部)雨季持续时间超过5个月(不足3个月)。(2)青藏高原雨季开始期与持续时间的年际变化幅度空间分布特征基本一致,其中,藏东南和柴达木盆地变化幅度较大;雨季结束期(降水量)的变化幅度明显偏小(大),雨季结束期变化幅度大(小)值区与降水量变化幅度小(大)值区相对应。(3)相比于雨季结束期,开始期与持续时间和降水量的关系更为密切,即雨季开始期早(晚)对应雨季持续时间长(短)和雨季降水量多(少)。(4)青藏高原雨季各特征量主要以唐古拉山(32.5°N)为界,呈现出南北反相的空间分布特征。相对于北部,南部雨季开始偏晚,结束早,持续时间短,降水量偏多、降水强度偏强。

云南高原昆明市城市发展对雨季长短变化的反馈

利用昆明站1991-2020年近30年逐日降水数据计算昆明雨季(5-10月)的起止时期,进一步确定昆明市雨季的长短。又基于云南省和昆明市的统计年鉴数据,使用年末总人口、城市建成区面积、城镇化率、人均GDP等城市发展因子确定昆明的城市发展进程,将昆明市的城市发展进程划分为缓慢发展期(1991-2003年)和快速发展期(2004-2020年),进而分析比较两段时期中昆明市雨季长短的特征和差异,采用统计分析、小波分析和M-K突变检验等综合分析方法,系统分析了昆明市雨季长短的时间变化特征,并用灰色关联度分析方法分析了昆明市雨季长短与城市发展的关联性。结果表明,1991-2020年昆明市的雨季开始日呈逐渐偏晚的趋势,而雨季结束日呈逐渐偏早的趋势,总体上雨季长度呈逐渐缩短的趋势;小波系数分析结果显示,在8年以下的时间尺度上,昆明市雨季长短变化的周期不存在明显的规律性,在17年时间尺度上的周期变化明显,呈偏短-偏长-偏短-偏长-偏短的5个循环交替,2003-2008年、 2014-2017年雨季增长,1991-2002年、 2009-2012年、 2018-2020年雨季缩短,2018-2020年等值线未闭合说明还有进一步缩短的趋势。通过M-K检验表明昆明市的雨季长短在1991-2020年间出现4次突变,分别发生在2002年、 2008年、 2012年和2017年。从昆明城市发展与雨季长短的关系来看,昆明城市发展缓慢期的雨季长短的变化趋势较为平稳,而城市发展快速期2004年以后,昆明市雨季长度缩短的变化明显,并随着城市发展进程的加快其极端波动性更加明显。运用SPSS(Statistical Product and Service Solutions)软件对未来10年昆明的雨季长短进行预测,结果显示未来10年昆明雨季长短将持续偏短的趋势。在灰色关联度分辨率为0.5时,表征城市发展进程的4个因子对昆明雨季长短变化均产生不同程度影响,其关联度系数都在0.70以上,表明昆明城市发展与雨季长短显著关联性,其中影响最大的因子是年末总人口,最小为人均GDP,灰色关联度分别为0.88和0.70,属于高度关联和显著关联。对4个因子的关联系数进行排序为:年末总人口>城镇化率>城市建成区面积>人均GDP。

湄公河典型区域旱雨季土地利用及土壤侵蚀差异研究

以湄公河干流老挝沙湾拿吉至柬埔寨桔井段重要支流南蒙河、色丹河、色贡河、色桑河、斯雷博河及其左右岸缓冲区50 km范围为研究区域,基于Landsat8遥感和河网数据,对比植被覆盖度以及空间分布特征,分析区域内旱季(1-2月)、雨季(6-9月)土地利用及土壤侵蚀变化。结果表明,季节性降雨导致土地利用变化明显,旱、雨季土地利用变化主要表现为河道沿岸水体动态变化;旱季水体面积较雨季净减少43 259 hm^(2),占总变化面积的93.8%;雨季至旱季耕地转化占总变化面积38.00%(17 514.44 hm^(2)),其次为灌木地(22.98%,10 590.54 hm^(2))和裸地(21.77%,10 033.32 hm^(2))。土地利用类型转化导致土壤侵蚀变化,旱、雨季土壤极强烈侵蚀和剧烈侵蚀区域变化不大;旱季以轻度侵蚀、中度侵蚀增加为主,净增加面积分别为4 107 hm^(2)和5 864 hm^(2),分别占总变化面积的36.9%和52.7%;增加面积主要由无侵蚀类型发展而来,体现在旱季沿岸水体面积的大幅降低。建议在水土保持过程中,改传统稻田种植为耕作、轮作和培肥一体化的水保措施,增强基础设施建设,加强河岸带生态护坡建设与管理,降低自然洪水或人为工程对自然林地和植被的破坏。

喀斯特石山老龄林檵木根际和非根际土壤微生物群落及酶活性的旱、雨季节变化

为了解喀斯特地区土壤生物活性的季节变化及其影响因素,该文以檵木群落老龄林阶段根际和非根际土壤微生物群落为研究对象,探讨其酶活性变化以及与环境因子的关系。结果表明:(1)雨季时,根际土壤pH值、有机质、全碳、全氮、全钾、全磷含量和碱性磷酸酶、过氧化氢酶、脲酶活性低于非根际土壤,说明根际土壤养分淋失更严重且影响相关酶活性,旱季变化相反是根际土壤为供植物健康生长所采取的养分富集策略。(2)根际和非根际土壤真菌多样性为旱季显著高于雨季,非根际土壤细菌多样性为雨季显著高于旱季,但根际土壤细菌多样性季节差异不明显;无论旱季还是雨季,根际和非根际土壤优势真菌门为子囊菌门(Ascomycota)、被孢霉门(Mortierellomycota)和担子菌门(Basidiomycota),优势细菌门为放线菌门(Actinobacteriota)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota);季节变化对根际和非根际土壤微生物群落结构影响差异显著。(3)不同季节下根际和非根际土壤微生物群落的主导因子不同,雨季时,根际土壤为pH、过氧化氢酶和碱性磷酸酶活性,非根际土壤为过氧化氢酶、碱性磷酸酶、纤维素酶活性和全钾含量;旱季时,根际土壤为过氧化氢酶活性和土壤含水量,非根际土壤为纤维素酶和蔗糖酶活性;土壤酶活性与碳、氮、磷、钾及土壤含水量显著相关。(4)与细菌相比,根际和非根际土壤真菌功能对季节变化的响应更敏感。综上表明,根际和非根际土壤微生物群落及酶活性在雨季和旱季时所采取的适应性策略明显不同,这为喀斯特地区植被恢复和土壤演替提供了理论参考。

煤矿雨季“三防”管理体系评价指标的构建

为解决煤矿雨季期间灾害频发问题,采用专家咨询和问卷调查方法,构建了涵盖防汛、防排水和防雷电三个准则层,以及排洪沟、滑坡及泥石流和雨季降水量等十三个指标层的煤矿雨季“三防”管理体系的评价指标体系,利用熵权法和灰色综合评估法进行指标权重的计算。结果表明,雨季降水量、雷电预警系统和建筑物防雷设施的权重较高,分别为0.1120、0.1095、0.1010。给出应加强排水、防雷等“三防”设施的建设和维护、地质灾害的监测和预警等针对性防治措施。该研究可提升煤矿的安全性和生产效率,降低事故发生的可能性,保障工人的生命安全。

梅雨季节对水产养殖的影响及应对措施

6月中旬开始,华东地区又将陆续进入梅雨季节,一般会持续至7月上旬,梅雨季节天气特点是多雨、低压,入梅前后的池塘管理工作直接影响养殖品种在后续阶段的生长状态。为了更好地帮助养殖户了解梅雨季节的管理措施及进行病害防治,《科学养鱼》采访了江苏农牧科技职业学院袁圣副教授和中国水产科学研究院长江水产研究所周勇副研究员。

云南区域夏季风雨季爆发前后大气热源和云量特征

本研究应用2001~2020年欧洲中期天气预报中心第五代再分析资料(ERA5)的气象场及卫星反演的降水和云量资料,研究了云南区域夏季风雨季爆发前后大气热源和云量的气候特征。研究结果表明:(1)云南区域的大气热源和云量会受夏季风环流的强烈影响,有着明显的逐月变化。6月受来自孟加拉湾东部的西南气流水汽输送影响,云南季风雨季爆发,大气总热源(特别是降水凝结释放的潜热)和云量较4~5月明显增强,而地表感热和大气辐射冷却作用减小。(2)基于Wang and LinHo(2002)方法计算的2001~2020年期间云南夏季风雨季的平均爆发时间约为第31候,区域大气总热源(潜热)和云量均与降水呈现出高度的时间相关性,而且云南区域大气热源和云量随夏季风雨季的时间变化呈现出与相邻的南亚热带季风区相似的单峰年变化特征。(3)云南夏季风雨季爆发时间存在明显的年际变化,雨季爆发偏早(晚)年的合成结果表明:在偏早年雨季爆发时,来自孟加拉湾东南部的低层西南气流可直达云南区域,该区域上空为辐散气流,有利于区域上升运动,云南区域大气总热源(潜热)和云量明显强于偏晚年;偏晚年同时段的孟加拉湾南支槽偏弱,西太平洋副高位置明显偏西,不利于云南区域上升运动和降水。在雨季盛期,偏早和偏晚年的区域降水率接近,偏晚年的区域大气总热源(潜热)和高云量值略高于偏早年。

1961-2017年青海高原雨季和降水的变化特征

基于青海高原46个气象观测站1961-2017年逐日降水观测资料,采用REOF方法将整个高原分为3个区域,分析不同区域雨季起讫期、降水量的分布态和变化特征。结果表明:(1)自高原东南部向西北部雨季开始期逐渐推迟、结束期逐渐提前、持续期逐渐缩短、降水量逐渐减少;(2)在高原西北部和南部地区经度变化对雨季影响明显,经度每增加1°,雨季开始期分别提前2.4 d和2.0 d;结束期分别推迟2.3 d和1.2 d;持续期分别延长4.6 d和3.2 d。(3)海拔对整个高原的雨季降水量影响很大,在海拔相对较低的高原西北部和东部地区,每上升100 m,降水量分别增加46.8 mm和8.3 mm,而在平均海拔4000 m以上的高原南部地区,每上升100 m,降水量减少20.3 mm。(4)1961-2017年高原平均雨季开始期平均每10年提前1.4 d,结束期推迟0.8 d,持续期延长2.2 d,降水量增加6.5 mm。(5)高原雨季降水极端性增强,尤其是2007年以来表现明显,2007年前后中雨日数、1日最大降水量、强降水量和降水强度分别增加1.0 d、9.3%、16.9%和0.4 mm·m^(-1)。

东亚夏季风和中国雨季的趋势变化和关键区气温和海温的影响

中国降水主要受到西风和季风环流的共同影响,表现出显著的年循环特征。本文基于1961~2020年CN05.1逐日降水资料和JRA55、CRU、HadISST再分析资料,采用谐波分析、相关和回归统计方法,分析了过去60年的东亚夏季风(中国雨季)的建立(开始)、撤退(结束)和持续时间等年循环参数趋势的变化特征。结果显示,自1961年以来,东亚夏季风有建立时间提前,撤退时间推后,持续时间增长的趋势,每十年分别达到了3.54、1.64、5.18天。1999年前后22年我国雨季也存在趋势变化,且在空间上存在显著差异。最近22年(1999~2020年),我国雨季提前主要集中在东北东部、青藏高原东部、西北北部地区,提前时间达5天以上,部分地区超过了20天。雨季滞后主要集中在青藏高原东北,长江以北和西部地区,时间超过了10天。雨季持续时间增加主要集中在青藏高原东北部、我国长江以北、东北东南部地区,时间超过15天以上,部分地区超过25天。研究发现,4月份环贝加尔湖地表气温增加及其伴随的局地反气旋性环流异常,是东亚夏季风建立和我国雨季开始时间提前的关键,而10月份的西北太平洋海温增暖及其伴随的西北太平洋副热带反气旋的异常是导致东亚夏季风撤退和中国北方雨季变长的关键。

一种华北夏季潜势雨季监测方法

针对华北夏季雨季监测存在的难题,提出了华北夏季潜势雨季概念,并建立了一种新监测方法——比湿副高法。主要监测结果如下:1961—2022年平均华北夏季雨季开始日期为7月10日,结束日期为8月8日,雨季长度为28 d;华北雨季起止时间无明显长期变化趋势,但年代际变化明显。该方法监测到的华北夏季雨季降水量、雨季综合强度指数与夏季降水量变化非常一致,为高度正相关,表明监测到的各雨季参数对华北夏季降水变化具有很好的指示性。华北夏季雨季开始、结束伴随着大气环流的明显变化:850 hPa层东亚副热带夏季风增强与减弱、30°N以北华北地区大气比湿迅速增大与减小;500 hPa层高度场在华北地区出现正、负距平中心,西北太平洋副热带高压在东亚沿岸开始明显北抬或东撤;200 hPa层高空西风急流轴由37.5°N附近北移到41.5°N附近或由44.5°N附近南移到40.5°N附近。

粤北南岭典型林分旱雨季冠层降水化学变化

全球气候变化背景下,降水时空分布不均导致季节性干旱形势愈发严峻。为探讨旱雨季时期亚热带典型林分冠层对降水化学的分配和淋溶特征,以南岭针阔混交林和常绿阔叶林为研究对象,对大气降水、穿透水和树干茎流pH、TN、TP、NH_(4)^(+)-N、NO_(3)^(-)-N、Cu、Cd、Pb和Cr^(6+)质量浓度进行测定及分析。结果表明:1)旱季大气降水呈酸性,经常绿阔叶林冠层后pH值为6.82,降水酸性得到缓冲。2)大气降水化学输入主要以氮磷养分为主,重金属输入量仅占1.19%~1.44%;雨季大气降水化学输入总量高于旱季,雨季为4198.4 g/hm^(2),旱季为3251.5 g/hm^(2)。3)旱季常绿阔叶林冠层中和作用优于其他2种林分,旱季3种林分穿透水和树干茎流中化学物质浓度多高于雨季,旱季3种林分冠层对降水化学成分表现为淋溶作用,雨季仅有针阔混交林(含竹)冠层对降水化学淋溶作用明显。4)Cu在冠层降水中的淋溶程度极高,净淋溶沉积比介于1.22~16.4之间,可能是致使水体污染的重要指标。

平衡火罐联合中医辨证施护在梅雨季节感冒的护理观察

临床分析平衡火罐联合中医辨证施护在梅雨季节感冒的应用观察。方法 回顾性方法分析,选取于2021年、2022年5-8月干预的60例梅雨季节感冒患者为研究对象,受试者以干预方法不同被分为两组,以30例为一组,患者均给予中医辨证施护措施,观察组联合给予平衡火罐。结果 从临床疗效的较比结果可以看出,观察组以93.33%处于优势(P<0.05);从中医症状积分的较比结果可以看出,经干预,观察组(4.16±0.86)低于对照组(6.24±0.15);干预后,观察组的生理领域(82.45±1.37)、心理领域(87.90±0.28)、社会关系领域(89.03±0.67)、环境领域(89.46±0.26)评分较对照组的生理领域(75.25±1.03)、心理领域(75.22±0.18)、社会关系领域(79.34±0.22)、环境领域(79.26±0.17)评分高(P<0.05);从护理满意度的较比结果可以看出,观察组满意情况更佳(P<0.05)。结论 梅雨季节感冒患者采用平衡火罐联合中医辨证施护,可取得较满意的临床效果,值得推广应用。

西南雨季降水变化与海温的关系

为了研究中国西南雨季降水变化和海温的关系,利用西南地区1960~2022年81站共63年的逐日气象观测降水量资料、同期英国哈德莱中心月平均海表温度(SST)资料(格点分辨率为1˚ × 1˚)、欧洲气象资料中心(ERA-interim)的月平均降水再分析资料(格点分辨率为0.25˚ × 0.25˚)。通过相关分析、经验正交函数分解(EOF)和奇异值分解(SVD)等方法,对西南雨季降水变化与全球SST之间的关系进行了研究分析,结果表明:1) 西南地区63年的雨季降水空间分布不均,呈现东多西少,南多北少的态势,同时,其与前冬、春季澳大利亚东北部太平洋,夏、秋季北印度洋和同期5⁓10月份的北印度洋海温呈现显著负相关关系,即关键区海温异常偏暖(冷),西南雨季降水偏少(多)。2) EOF分析表明:在第1模态下,前一年冬季和当年春季关键区海域海温的分布形式多呈现出西高东低的形式,包括了东太平洋冷舌和西太平洋暖池形态,并且在千禧年之前大部分都是海温多为偏冷状态;而千禧年之后关键区海温由偏冷转为偏暖状态。而当年夏秋季和雨季同期关键区海域海温呈现出全区一致偏暖状态,并且在90年代之后海温从偏冷转变为偏暖状态,其第2空间模态为印度洋正偶极子分布形式。3) SVD分解表明:关键区海温与川西高原地区雨季降水存在正相关关系,而与川东、黔南和云南呈现出一个显著的负相关性,不同季节的海温关键区影响的降水大值区域可能略有不同,但总体来说,当关键区海温异常偏高(低),川西高原的雨季降水异常偏多(少),而其余大部分地区降水异常偏少(多);其分解结果与相关系数的分析结果基本一致并且近年来西南地区的雨季降水呈现出逐年减少的态势。In order to study the relationship between precipitation change and sea surface temperature in the rainy season in southwest China, the daily meteorological observations of 81 stations in Southwest China from 1960 to 2022 for a total of 63 years were used measured precipitation data, the monthly mean sea surface temperature (SST) data of the Hadley Center in the United Kingdom (grid resolution of 1˚ × 1˚) and the monthly mean precipitation reanalysis data of the European Meteorological Data Center (ERA-interim) (grid resolution of 0.25˚ × 0.25˚). The relationship between precipitation change in the rainy season in southwest China and global SST was analyzed by correlation analysis, empirical orthogonal function decomposition (EOF) and singular value decomposition (SVD). The results shows: 1) The spatial distribution of rainy season precipitation in southwest China in 63 years was uneven, showing a trend of more precipitation in the east and less in the west, and more in the south and less in the north, and at the same time, it was significantly negatively correlated with the sea surface temperature in the Pacific Ocean in northeast Australia in the early winter and spring, the northern Indian Ocean in summer and autumn, and the northern Indian Ocean in May and October in the same period, that is, the SST in the key areas was abnormally warm (cold), and the precipitation in the southwest rainy season was less (more). 2) EOF analysis shows that in the first mode, the distribution of sea surface temperature in the key areas in the winter and spring of the previous year mostly shows the form of high in the west and low in the east, including the cold tongue of the eastern Pacific and the warm pool of the western Pacific, and most of the SST is in a cold state before the millennium. After the turn of the millennium, the sea surface temperature in key areas changed from cold to warm. However, the SST in the key areas of the key area in the same period of summer, autumn and rainy season showed a uniform warming state in the whole region, and after the 90s, the SST changed from cold to warm, and the second spatial mode was the normal dipole distribution of the Indian Ocean. 3) SVD decomposition showed that the sea surface temperature in the key area and the rainy season in the western Sichuan Plateau. There is a positive correlation with precipitation, and there is a significant negative correlation with eastern Sichuan, southern Guizhou and Yunnan, and the influence of key areas of SST in different seasons is positive. The precipitation area may be slightly different, but in general, when the sea surface temperature in the key area is abnormally high (low), the rainy season precipitation in the western Sichuan Plateau is abnormally biased more (less), while most of the rest of the precipitation is abnormally low (more). The decomposition results are basically consistent with the analysis results of the correlation coefficient and in recent years. The rainy season precipitation in southwest China shows a decreasing trend year by year.

西南雨季降水异常海气背景场特征

为了研究中国西南雨季降水异常海气背景变化场特征,利用西南地区1960~2022年81站共63年的逐日气象观测降水量资料、同期英国哈德莱中心月平均海表温度(SST)资料(格点分辨率为1˚ × 1˚)、欧洲气象资料中心(ERA-interim)的月平均降水再分析资料(格点分辨率为0.25˚ × 0.25˚)、欧洲气象资料中心月平均位势高度(200 hPa,500 hPa,700 hPa及850 hPa)和风场等再分析资料(格点分辨率为2.5˚ × 2.5˚)。通过相关分析、合成分析等方法,对西南雨季降水异常海气背景变化场特征进行了研究分析,结果表明:1) 海温异常年份做西南地区雨季降水合成分析时,当前一年冬季和当年春季西太平洋暖池海域的海温异常偏高而东太平洋冷舌海温异常偏低,当年夏秋季和雨季同期北印度洋海域整体海温偏高时,西南雨季降水偏少,降水多在青藏高原,川南部分区域及贵州西南部发生;而当四季和同期海域海温异常偏低时,此时降水偏多,且多集中发生在云南大部、贵州和川东等区域。2) 降水异常年份做海温合成分析时,当西南雨季降水偏多时,四季和同期海域海温整体异常偏低;当西南雨季降水偏少时,夏秋季和同期北印度洋海温分布并不是全区一致型,而是呈正IOD位相分布形势。3) 大气环流异常形势表明:当四季和同期海域海温异常偏高时,高层南亚高压异常东移,中层西太平洋副热带高压进一步西伸,低层来自孟湾和南海–西太平洋的水汽输送减少,导致西南地区除川西地区外大部降水减少,而高原雨季降水增加;在海温异常偏低时,南亚高压和西太平洋副热带高压强度较弱,位置并没有明显的东移和西伸,低层水汽输送又进一步增加,除川西高原降水减少以外,西南地区大部雨季降水增加。In order to study the characteristics of the sea-air background variation field of precipitation anomalies in the rainy season in southwest China, the daily meteorological observation precipitation data of 81 stations in southwest China for a total of 63 years from 1960 to 2022, the monthly mean sea surface temperature (SST) data of the Hadley Center in the United Kingdom during the same period (grid resolution of 1˚ × 1˚), and the monthly mean precipitation reanalysis data of the European Meteorological Data Center (ERA-interim) (grid resolution of 0.25˚ × 0.25˚), European Meteorological Data Centre (ERA-interim) monthly mean geopotential altitude (200 hPa, 500 hPa, 700 hPa and 850 hPa) and wind field reanalysis data (grid resolution of 2.5˚ × 2.5˚). Correlation analysis and synthesis analysis were used to study and analyze the characteristics of the sea-air background variation field of precipitation anomalies in the rainy season in southwest China. The results show that: 1) When the SST anomaly year is used for the synthesis analysis of precipitation in southwest China, the SST in the warm pool of the western Pacific Ocean is abnormally high in the winter and spring of the current year, and the SST in the cold tongue of the eastern Pacific is abnormally low, and when the overall SST in the northern Indian Ocean is high in the summer and autumn of the year and the same period of the rainy season, the precipitation in the southwest rainy season is low, and the precipitation mostly occurs in the Qinghai-Tibet Plateau, some areas of southern Sichuan and southwest Guizhou. When the sea surface temperature is abnormally low in the four seasons and the same period, the precipitation is more at this time, and most of it occurs in most of Yunnan, Guizhou and eastern Sichuan. 2) When the SST synthesis analysis was performed in the precipitation anomaly years, when the precipitation in the southwest rainy season was too much, the overall sea surface temperature in the four seasons and the same period was abnormally low. When the precipitation in the southwest rainy season is low, the distribution of SST in the northern Indian Ocean in summer, autumn and the same period is not consistent across the whole region, but shows a positive IOD phase distribution pattern. 3) The anomalies of atmospheric circulation show that when the sea surface temperature is abnormally high in the four seasons and the same period, the upper South Asian high anomaly moves eastward, the middle western Pacific subtropical high extends further westward, and the low-level water vapor transport from the Ben Bay and the South China Sea-Western Pacific decreases, resulting in a decrease in precipitation in most parts of southwest China except for western Sichuan, and an increase in precipitation in the plateau during the rainy season. When the SST is abnormally low, the intensity of the South Asian high and the western Pacific subtropical high is weak, and the position does not move eastward or westward significantly, and the low-level water vapor transport further increases, except for the decrease of precipitation in the western Sichuan Plateau, the precipitation in most of the southwest region increases in the rainy season.

西南雨季不同年代降水特征对比分析

为了更好地对西南雨季降水的时空变化特征进行研究,利用中国西南地区1960~2022年81个气象站点共63年的逐日降水量气象观测资料,通过经验正交函数分解(EOF)、线性趋势倾向分析和Morlet小波分析等研究方法,揭示西南地区降水的时空分布特征、长期变化趋势以及周期变化特征。分析结果表明:(1) 西南地区1960~2022年的雨季降水量总体呈现下降趋势,其年代际变率为−12.516/10a,降水距平值呈现下降趋势,且降水存在周期性变化。(2) 西南雨季降水量的EOF分析表明:第1模态表明西南地区降水呈全区一致型分布;第2模态呈现南北反位相的分布类型;第3模态降水为由南向北呈现“正–负–正”的分布类型;第4模态降水呈现西北–东南反向的分布类型。(3) 除川西高原地区外,年代降水距平值呈先增后减的趋势,其他区域的年代降水距平值无明显变化规律。西南地区雨季的年代降水距平百分率属于正常变化。In order to better study the spatio-temporal variation characteristics of rainy season precipitation in Southwest China, the day-by-day precipitation meteorological observations from 81 meteorological stations in Southwest China for a total of 63 years from 1960 to 2022 are utilized to reveal the spatio-temporal distribution characteristics of precipitation in Southwest China, the long-term trend by means of the empirical orthogonal function decomposition (EOF), the linear trend tendency analysis and the Morlet wavelet analysis, and the cyclic variation characteristics and cycle change characteristics. The analysis results show that: (1) The rainy season precipitation in Southwest China from 1960 to 2022 shows an overall decreasing trend, and its interdecadal variability is −12.516/10a, the precipitation distance level shows a decreasing trend, and there are cyclic changes in precipitation. (2) The EOF analysis of the rainy season precipitation in Southwest China shows that: mode 1 indicates that the precipitation in Southwest China is uniformly distributed throughout the region;mode 2 shows a north-south antipodal distribution;mode 3 shows a “positive-negative-positive” distribution from the south to the north;and mode 4 shows a northwesterly-southeasterly inverse distribution. (3) Except for the Western Sichuan Plateau area, the distance level of the chronological precipitation shows a tendency of increasing and then decreasing, and there is no obvious pattern of change in the distance level of the chronological precipitation in other areas. The percentage of chronological precipitation distance level in the rainy season in the southwestern region belongs to the normal change.

基于EEMD的西南雨季降水的多尺度变化特征

利用1960~2022年西南地区81个气象站点共63年的逐日气象降水量观测资料,运用旋转经验正交函数分解(REOF)、Morlet小波分析和集合经验模态分析(EEMD)等方法,对西南地区63年雨季降水量的多尺度变化特征进行了详细研究。结果表明:根据REOF分析表明:第1模态高值区主要在云南地区,低值在川西高原及四川东部;第2模态高值区主要在云南东南部和四川东部,低值区在川西高原;第3模态高值区主要在四川中部及北部,第4模态高值区主要在贵州地区,第5模态高值区主要在四川东部。根据高荷载量以及各种因素可以把西南地区分为5个区域,分别为云南区、川西高原区、川东区、川中区以及贵州区。小波分析表明云南区主要存在准3a、准8a、准23a的降水周期;EEMD分解表明云南区主要有3.2年、6.4年、9.6年、21.3年的周期。小波分析表明川东地区主要存在准7a、准13a、准22a的降水周期;EEMD分解表明川东区主要有3.36年、8年、26.6年的周期。小波分析表明川西高原区主要存在准4a、准8a、准15a、准18a的降水周期;EEMD分解表明川西高原区具有3年、6.4年、8.6年、21.3年的周期。小波分析表明川中区主要有准4a、准6a、准10a、准16a、准27a的降水周期;EEMD分解表明川中区主要有2.78年、7.6年、16年的周期。小波分析表明贵州区主要有准7a、准11a、准15a和准20a的降水周期变化;EEMD分解表明贵州区具有4.15年、10年、20年的周期。由此可知,西南地区主要存在4年、8年和20年左右的周期。Utilizing day-by-day meteorological precipitation observations from 81 meteorological stations in Southwest China for a total of 63 years from 1960 to 2022, the multi-scale variation characteristics of precipitation during the 63-year rainy season in Southwest China were studied in detail by means of Rotation Empirical Orthogonal Function decomposition (REOF), Morlet wavelet analysis and Ensemble Empirical Mode Decomposition analysis (EEMD). The results show that: According to the REOF analysis, the high value of mode 1 is mainly in Yunnan, and the low value is in western Sichuan Plateau and eastern Sichuan. The high value area of mode 2 is mainly in southeast Yunnan and eastern Sichuan, and the low value area is in western Sichuan Plateau. The third mode high value area is mainly in the central and northern part of Sichuan, the fourth mode high value area is mainly in Guizhou, and the fifth mode high value area is mainly in the eastern part of Sichuan. According to the high load capacity and various factors, the southwest region can be divided into five regions, namely Yunnan region, western Sichuan Plateau region, eastern Sichuan region, central Sichuan region and Guizhou region. Wavelet analysis shows that there are mainly quasi-3a, quasi-8a and quasi-23a precipitation cycles in Yunnan. The EEMD decomposition shows that there are 3.2, 6.4, 9.6 and 21.3 years in Yunnan region. Wavelet analysis shows that there are quasi-7a, quasi-13a and quasi-22a precipitation cycles in eastern Sichuan. The EEMD decomposition shows that there are 3.36 years, 8 years and 26.6 years in eastern Sichuan. Wavelet analysis shows that the precipitation periods of quasi-4a, quasi-8a, quasi-15a and quasi-18a mainly exist in the western Sichuan Plateau. The EEMD decomposition shows that the western Sichuan Plateau has a period of 3 years, 6.4 years, 8.6 years and 21.3 years. Wavelet analysis shows that the main precipitation periods in central Sichuan are quasi-4a, quasi-6a, quasi-10a, quasi-16a and quasi-27a. The EEMD decomposition shows that there are 2.78 years, 7.6 years and 16 years in central Sichuan region. The wavelet analysis shows that there are mainly quasi-7a, quasi-11a, quasi-15a and quasi-20a precipitation cycles in Guizhou. The EEMD decomposition shows that the Guizhou region has 4.15-year, 10-year and 20-year cycles. It can be seen that there are cycles of about 4 years, 8 years and 20 years in southwest China.

西南雨季降水时空变化特征

为研究西南雨季降水的时空变化特征,利用1960~2022年西南地区81个气象站点的逐日气象降水量观测资料,通过EOF分解、Morlet小波分析和EEMD分析等方法,对西南地区雨季降水量的多尺度变化特征进行了详细研究。结果表明:1) 西南地区63年来雨季降水量空间分布不均匀,大体有由东向西逐渐递减,以及由南向北逐渐递减的变化趋势。川西高原为降水量低值区,雅安、峨眉以及云南南部为降水量高值区。西南地区趋势系数正值区和负值区交错分布,正值区主要在川西高原以及川东和贵州,负值区在云南地区。2) EOF分析表明:西南地区雨季降水量第1模态为全区一致型,大值中心位于云南地区以及四川中南部。西南地区雨季降水量第2模态显示为北负南正型,正值大值中心位于云南地区,负值大值区位于川西和川东。西南地区雨季降水量第3模态显示为东北到西南正负交错的分布类型。西南地区雨季降水量第4模态为西负东正的分布类型。西南地区雨季降水量第5模态显示为东北到西南呈正负交错的分布类型。3) 小波分析表明西南地区雨季降水量主要有3~4年、7~8年、10~14年、15~23年的变化周期;EEMD分解表明西南地区雨季降水量主要有2.66年、5.33年、10年、21.3年的变化周期。由此可知,西南地区主要存在4年、8年和20年左右的周期。In order to study the spatio-temporal variation of rainy season precipitation in Southwest China, the multi-scale variation of rainy season precipitation in Southwest China was studied in detail by means of EOF decomposition, Morlet wavelet analysis and EEMD analysis, based on the daily meteorological precipitation observation data of 81 meteorological stations in Southwest China during 1960~2022. The results show that: 1) The spatial distribution of rainy season precipitation in Southwest China in the past 63 years is uneven, with a gradual decline from east to west and from south to north. The West Sichuan Plateau has a low precipitation value, while Ya’an, E’mei and southern Yunnan have a high precipitation value. The positive and negative regions of the trend coefficient in Southwest China are interleaved, the positive regions are mainly in the west Sichuan Plateau, the east Sichuan and Guizhou, and the negative regions are in Yunnan. 2) The EOF analysis shows that the first mode of precipitation in the rainy season in southwest China is the uniform type in the whole region, and the large value center is located in Yunnan and central and southern Sichuan. The second mode of rainy season precipitation in Southwest China shows that the north is negative and the south is positive. The positive value center is located in Yunnan, and the negative value area is located in west and east Sichuan. The third mode of precipitation in the rainy season in Southwest China shows the distribution type of positive and negative interleaving from northeast to southwest. The fourth mode of precipitation in the rainy season in Southwest China is the distribution type of west negative and east positive. The fifth mode of precipitation of rainy season in Southwest China shows the distribution type of positive and negative from northeast to southwest. 3) Wavelet analysis shows that the rainy season precipitation in Southwest China mainly has a change cycle of 3~4 years, 7~8 years, 10-14 years and 15~23 years. The EEMD decomposition shows that the rainy season precipitation in Southwest China mainly has a change cycle of 2.66 years, 5.33 years, 10 years and 21.3 years. It can be seen that there are cycles of about 4 years, 8 years and 20 years in Southwest China.

西南雨季降水异常水汽输送变化特征

为了研究西南地区存在的异常水汽输送的变化特征,利用西南地区81个气象台站点1960~2022年共63年的逐日气象降水量观测资料和同期ERA5逐月再分析资料,数据的网格分辨率0.25˚ × 0.25˚,通过天气学诊断分析、径向基函数插值算法、t检验法和显著性检验等方法,对西南地区的雨季异常水汽输送特征进行了详细研究,其研究结论表明:1) 西南地区雨季降水量自1960年起呈现显著下降趋势,具有约11年的周期性变化周期内分布并不均匀,多为上升慢,跌落快。当前正处于新周期的起始阶段,预计将经历一个缓慢的上升期。2) 每30划分一个年际为统计口径,越靠近当下的年际的雨季降水量越低,水汽输送也越弱,代表水汽输送的水汽通量散度和垂直积分都会越低,垂直积分的下降趋势略弱于散度。3) 西南地区还存在一个异常区域位于103˚E~106˚E区域,该区域内站点之间存在水汽输送的共通性,水汽输送和异常降水都与整体相反,拥有相对独立水汽输送通道,根据四轮30年际统计发现异常带将逐渐扩大,空间上沿向外扩散,伴随整体周期性的上升,除异常带外的其他地区将经历水汽输送和雨季降水的增长,而异常带地区将呈现与整体趋势相反的异常低值。To investigate the characteristics of anomalous water vapor transport in Southwest China, we utilized daily precipitation observations from 81 meteorological stations in Southwest China spanning 63 years (1960~2022) and monthly ERA5 reanalysis data with a grid resolution of 0.25˚ × 0.25˚. Through synoptic diagnostic analysis, radial basis function interpolation, t-test, and significance testing, we conducted a detailed study on the characteristics of anomalous moisture transport during the rainy season in Southwest China. The study concluded that: 1) Since 1960, the rainy season precipitation in Southwest China has shown a significant downward trend, characterized by an approximately 11-year periodic cycle. Within this cycle, the distribution is uneven, with a slow rise and a rapid fall. Currently, it is at the beginning of a new cycle, expected to experience a slow upward trend. 2) When dividing into 30-year intervals for statistical purposes, the closer to the present, the lower the rainy season precipitation and the weaker the moisture transport. This is reflected in lower moisture flux divergence and vertically integrated moisture transport, with the decline in vertical integration being slightly less pronounced than that in divergence. 3) An anomalous region exists between 103˚E and 106˚E, where the meteorological stations exhibit commonality in moisture transport. Both moisture transport and anomalous precipitation in this region are contrary to the overall trend, indicating a relatively independent moisture transport channel. Statistical analysis over four 30-year intervals reveals that this anomalous belt is gradually expanding spatially, with the anomaly spreading outward. As the overall periodic rise continues, regions outside the anomalous belt will experience growth in moisture transport and rainy season precipitation, while the anomalous belt will exhibit anomalously low values opposite to the general trend.