【作者】 周晓英；

【导师】 王赐震；

【作者基本信息】 中国海洋大学 ， 海洋气象学， 2005， 硕士

【摘要】 本文利用:(1)长江口引水船海洋站1959年9月～2001年10月月平均表层水温(SST)资料(共42年),1998年1月1日～12月31日日平均SST资料(1年),(2)大戢山海洋站1977年10月～2000年4月月平均SST资料(共22年),1998年1月1日～12月31日日平均SST资料(1年),(3)安徽大通水文站1968年1月～1999年12月(32年)月平均径流量资料,(4)1959年～2001年(43年)美国NCEP-NCAR再分析月平均大气环流资料,分析了长江口区表层水温变化的气候特征。对长江口SST的日变化、季节变化、年际变化、年代际突变都进行了分析;主要讨论了对长江口SST季节和年际变化有影响的重要因子:东亚季风(包括冬季风和夏季风)和长江径流对长江口海域SST的影响。通过对长江口SST变化规律的研究,对长江口海域SST的短期、中期、长期预报及长江口的赤潮预报和渔业生产,都有一定的实用价值和指导意义,对长江口SST变化的气候预测提供可靠的依据。 1 首先分析了长江口SST的日变化。在一年四个季节中,引水船春季日较差最大,最大日较差达4.7℃。大戢山站初夏和初冬日较差最大,最大日较差达2.5℃。长江口SST日变化比相同水深的外海海域变化显著。普查历史天气图,发现日较差大的天数,控制长江口的天气系统为高压中心,说明太阳辐射是长江口SST日变化的主要原因,长江口层结稳定、长江冲淡水的流经亦是其日变化大的原因。 2 分析了长江口SST的季节变化,一年中长江口SST最高值出现在8月份,最低值出现在2月份。春、秋季为过渡季节,春季(3～5月)为水温上升季节,秋季(9～11月)为水温下降季节。从方差分布看,与平均值最大出现在夏季8月不同,方差最大值出现在冬季(12～2月),SST年际变化呈现出季节差异,冬季SST年际变化比夏季大。引水船最大方差出现在1月份,而大戢山最大方差出现在12月份,说明引水船1月份水温变化幅度最大,大戢山12月份水温变化幅度最大。引水船方差变化范围在0.43～1.65之间,大戢山方差变化范围在0.26～1.45之间。引水船方差变化范围比大戢山大,这是因为引水船受陆地气候影响较大。太阳辐射及东亚季风、长江径流是影响长江口海域SST季节变化的主要因子。 3 通过功率谱分析,发现长江口SST的年际变化的主要周期是准两年和3～5年,这与不少学者对中国海的研究基本一致。 4 长江口SST的年代际变化可分为两个时期,20世纪60年代到80年代中后期,长江口SST多数年份是负距平,为相对冷期。80年代末以后,长江口SST多数年份是正距平,属暖期。长江口SST经历由冷到暖的变化过程,70年代最低,多为“冷水”年,90年代多为“暖水”年。用Mann-Kendall非参数统计检验方更多还原

【Abstract】 Based on the monthly average SST data for 42 years (1959.9~2001.10) and thedaily average SST data for one year (1998.1.1~ 1998.12.31) at Yin-shuichuan oceanstation in the Changjiang estuary, the monthly average SST data for 23 years(1977.10 ~ 2000.4) and the daily average SST data for one year (1998.1.1 ~1998.12.31) at Da-jishan ocean station in the Changjiang estuary , the monthlyaverage Changjiang runoff discharge data for 32 years(1968.1 ~ 1999.12) at Da-tonghydrological station in AnHui Province, the monthly average reanalysis data ongeneral circulation from the NCEP/NCAR for 43 years(1959~2001),it is analyzedthe climate characteristics of the SST variation in the Changjiang estuary. It isstudied the daily、 monthly 、seasonal、 interannual and decadal years SST variation inthe Changjiang estuary. It is mainly discussed the important factors that effect theseasonal and interannual SST variation in the Changjiang estuary : it includes theaffect of the East-Asia monsoon and the Changjiang runoff to the SST variation.The studies on SST variation provide reliable evidence for short、 medium、 long termforecast and climatic prediction of SST in the Changjiang estuary ,it also benefits thefish production in the Changjiang estuary.1 Firstly it is analyzed the daily SST variation in the Changjiang estuary. Among four seasons the most daily SST deficit appears in spring at Yin-shuichuan station with 4.7℃ and in early summer and early autumn at Da-jishan station with 2.5℃ .By the weather chart, it is found that the Changjiang estuary is controlled by the center of high pressure on the most max daily SST deficit day. The Sun radiation is the main factor of SST daily variation.2 The seasonal SST variation in the Changjiang estuary is studied .The highest SST appears in August and the lowest SST in February among a year. Spring and Autumn are transition seasons in a year. In Spring the SST rises from March to May. In Autumn the SST declines from September to November. The biggest distribution of SST variance is in winter with being in January at Yin-shuichuan station and in December at Da-jishan station. The Sun radiation 、 the East Asia monsoon and changjiang run-off are the main affecting factors.3 By power spectrum analysis, it is showed that there are about 2-year and 3~ 5 year oscillations for SST annual variation in the Changjiang estuary. This conclusion corresponds with the results of China sea SST that many researchers havediscovered.4 The interdecade variation is divided into two periods: from 60s to the end of 80s of 20 century, SST was relatively "cold times" that in most of years SSTA(SST anomaly) are negative , from the end of 80s of 20 century to the early 21-century, SST was relatively "warm times" that in most of years SSTA(SST anomaly) is positive. The SST variation become warmer, the SST was lowest in 70s in the last century, and most of years are "cold -water" year. The SST was the highest in 90s in the last century and most of years are "warm -water" year. The abrupt change year for SST took place in 1989.5 By the compose analysis , it is studied the East-Asian monsoon influence to the SST annual variation in the Changjiang estuary. According to the analysis of 500hPa heights 850hPa wind velocity and sea surface pressure, it is showed that in winter the strong winter monsoon year is corresponded with cold water year and weak monsoon year is corresponded with warm water year for SST in the Changjiang estuary. In summer when the year is strong summer monsoon year, the SST is abnormally higher. When the year is weak summer monsoon year, the SST is abnormally lower.6 Based on correlation analysis, it is studied that the Changjiang run-off effects the seasonal and annual SST variation in the Changjiang estuary. The direct influence of Changjiang run-off to the SST seasonal variation appears in March and April in dry season. In flash season the Changjiang run-off has indirect influence to the SST of the Changjiang estuary after one^ two^ three month. The Changjiang run-off discharge have 6.9a ^ 3.5a and 1.5a oscillations . The Changjiang run-off also effects the annual SST variation: when the yearly-mean run-off discharge is bigger, the SST in the Changjiang estuary is higher. Others the SST is lower.更多还原