兰州大学机构库 >大气科学学院
浙江地区夏季高温气候特征及其影响因子研究
Alternative TitleA study of the summer high temperature characteristics and impact factors in Zhejiang, China
李琼
Thesis Advisor马玉霞 ; 许娈
2018-09-03
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Degree Discipline气象学
Keyword气候特征 高温日 高温热浪 西太平洋副热带高压 浙江地区
Abstract全球气候变化是21世纪人类所面临的最主要环境问题之一,而随着气温的持续升高,全球各地极端高温事件频发,极端最高气温屡破历史同期极值,持续高温热浪日数明显增多,对社会发展、人类健康、农业、生态系统和基础设施都造成了广泛的影响。本文利用浙江71个国家基本/基准气象站1971-2017年的逐日最高气温(Tmax)资料、1971-2017年逐月的西太平洋副热带高压(western Pacific subtropical high,简称WPSH)面积指数和强度指数以及1971-2016年逐月NCEP/NCAR再分析资料的垂直速度、经向风、纬向风、位势高度等,用趋势系数法、合成分析以及奇异值分解(SVD)等方法,筛选出浙江地区高温日,并对夏季热浪的时空分布特征,包括年际变化、热浪过程、影响因子进行分析,主要研究结果如下:(1)本文根据浙江地形特征的差异将浙江划分为六个研究区域,分析发现年平均高温日数和年平均高温热浪过程次数的高值区主要位于浙西南地区,其中浙南山地高温日数和高温热浪过程分别为(24.8d-40.3d)和(3.34次-5.53次),浙西中山丘陵地区高温日数和高温热浪过程分别为(24d-31.1d)和(2.87-4.04次);浙中金衢盆地高温日数和高温热浪过程分别为(26.3d-35.3d)和(3.4次-4.53次)。然而进入21世纪后,浙北平原地区、浙东丘陵地区和浙东南沿海及滨海岛屿地区的高温日数和年平均最高气温上升趋势则较浙西南地区更为明显。其中浙北平原地区平均最高气温的逐年变化斜率为0.045(每100年增加4.5°C),远远高于浙江地区平均最高气温逐年增长的斜率0.0117(每100年增加1.17°C)。(2)本文将1971-2017年按照浙江地区高温日数进行排序发现,排名前五的年份依次为1971年、2013年、1994年(2007年)、2003年和2017年;而按照浙江地区高温日年平均最高气温进行排序则发现,排名前五位是2013年(37.20°C)、2003年(37.14°C)、2017年(36.99°C)、2016年(36.79°C)、1971年(36.73°C)。因此为综合考虑高温日数和高温日平均最高气温,本文将高温日数乘以高温日平均最高气温,将47年重新进行排序发现,夏季最热的五年则依次为1971年、2003年、2017年、2013年和1994年,并通过分析其所对应的500hpa高度场可发现,最热的五年,6月西太平洋副热带高压西伸脊点位于125°E以西,脊线位于20°N附近。最凉的五年,6月平均的500hPa高度场上,西太平洋副热带高压主体偏南偏东,其西伸脊点位于135°E附近,远离我国大陆。(3)浙江地区夏季高温日数与同期西太平洋副热带高压面积指数和强度指数的相关系数大致呈东部高西部低的分布形势。站点高温日数与西太平洋副热带高压面积和强度指数相关性显著的区域主要位于东部沿海地区及杭州湾周边地区,宁波、台州和温州大部分地区,相关系数达到0.4以上,通过0.005的显著性水平检验;相关性最为显著的地区位于台州南部及温州中北部,相关系数大于0.5,通过0.001的显著性水平检验;瑞安、永嘉和温岭三站的相关系数最高,分别为0.599、0.585和0.568。另外,金华南部的部分地区高温日数也与两个指数相关性较为显著。综合以上分析可以看出,西太平洋副热带高压主体面积较大、强度较强期间,与东部沿海地区的高温日数偏多密切相关,而对西部内陆地区的高温日数影响较小。(4)2017年浙江地区夏季高温日平均最高气温为37°C,与历史最高纪录2013年仅相差0.2°C,为近47年内高温日平均最高气温第三位。其中7月高温日平均最高气温更是达到37.4°C,比历史平均值高1.0°C,历史排名第二。而8月的平均高温日数为28d,远远超过历史平均值12.1d,并且打破1998年8月的历史最高纪录26d,排名历史第一。2017年夏季共有四次典型高温过程,分别为7月5日-7月8日、7月10日-7月29日、8月2日-8月11日和8月13日-8月30日。其中第二次高温过程是2017年浙江地区最强的一次高温过程。过程中7月21日至25日连续五天日平均最高气温达到38°C以上,而在24-25日甚至超过39°C,历史上极为少见。对四次高温过程对应的500hpa高度场分析发现,第二次高温过程中,西太平洋副热带高压表现尤为强盛,位置较前一过程显著西伸北抬,此时浙江位于副高极值中心附近,因此高温过程强度大、持续时间长。
Other AbstractGlobal warming is one of the most challenging environmental problems for human beings in the 21st century. As temperatures continue to rise, extremely high temperatures have become more frequent and constantly break historical records. The number of days with continuous heat waves has also significantly increased. Climate change has been greatly affecting societal development, human health, agriculture, ecosystems, and infrastructure. This study focused on summer heat waves in Zhejiang, China. We used historical daily maximum temperature records and monthly Western Pacific Subtropical High (WPSH) area and intensity indices during the period of 1971–2017 from 71 observing stations in the study province. Based on the monthly NCEP/NCAR reanalysis data from 1971 to 2016, we used the data of vertical velocity ,vertical wind ,zonal wind and geopotential height to screen the hot days by adopting the method of trend analysis ,synthetic analysis ,and singular value decomposition (SVD).We then investigated the local summer heat waves from four aspects: spatial distribution, interannual variations, processes of development, and impact factors. The main findings are as follows:(1) Zhejiang province consists of six topographical subareas, including the northern plain, western hills, eastern hills, central Jinqu Basin, southern upland, and southeastern coastal plain and island. Using an annual average scale, we detected the highest numbers of hot days and heat wave events in southwestern Zhejing. In particular, annual average number of hot days (heat wave events) was 24.8–40.3 (3.34–5.53), 24–31.1 (2.87–4.04), and 26.3–35.3 (3.4–4.53) in the southern upland, the western medium-slope hills, and the central Jinqu Basin, respectively. Since the year 2000, we found that both the number of hot days and annual mean maximum temperature have been significantly increasing in the northern plain, the eastern hills, and the southeastern coastal plain and island. Within these subareas, annual mean maximum temperature increased at a rate of 4.5 °C per century in the northern plain, which was significantly higher than the increase rate for the entire Zhejiang province (1.17 °C per century).(2) During the study period of 1971–2017, the number of hot days in Zhejiang was the highest in year 1971, followed by the four years of 2013, 1994 (tied with year 2007), 2003, and 2017. The annual mean maximum temperature was the highest in year 2013 (37.20 °C), followed by the four years of 2003 (37.14 °C), 2017 (36.99 °C), 2016 (36.79 °C), and 1971 (36.73 °C). When combining the two above indices, we defined the top five hot summer years as 1971, 2003, 2017, 2013, and 1994; we also found from the June 500hpa circulation field that the subtropical high ridge point was to the west of 125°E, and the ridge line was in the vicinity of 20°N ridge for these five years. Meanwhile, the average June 500hPa height field for the bottom five hot summer years showed that the subtropical high body was southward and eastward, and the westward ridge point was in the vicinity of 135°E, which was away from the mainland China.(3) In Zhejiang, the correlation coefficient between the number of hot days in summer and the WPSH area and intensity indices was generally high in the eastern region and low in the western region. Relatively high correlation coefficient (above 0.4, p ≤ 0.05) mainly showed in the eastern coastal area, Hangzhou Bay surrounding area, Ningbo, Taizhou, and most of Wenzhou. The highest correlation coefficient (above 0.5, p ≤ 0.01) was in the south of Taizhou and north central area of Wenzhou, especially in the three observing stations of Rui'an (0.599), Yongjia (0.585), and Wenling (0.568). In addition, the correlation coefficient was relatively high in the south of Jinhua. We concluded that the number of hot days in summer on the east coast was closely related to the WPSH area and intensity indices, while this correlation was relatively weak for the west inland.(4) In Zhejiang, the mean maximum temperature during the hot days in summer in 2017 was 37 °C (ranked No. 3 in the study period), which was only 0.2 °C lower than the historical record in 2013. During the hot days in summer in 2017, July mean maximum temperature was 37.4 °C (ranked No.2 in the history), which was 1.0 °C higher than the historical average; August average number of hot days was 28, which was much higher than the historical average of 12.1d and, what’s more, this broke the historical record of 26d in 1998. There were four typical high temperature processes in the summer of 2017, including July 5th–July 8th, July 10th–July 29th, August 2nd–August 11th, and August 13th–August 30th. Of these, the high temperature process during July 10th–July 29th was the strongest. From July 21st to 25th, the average daily maximum temperature in Zhejiang was consecutively above 38°C (above 39°C from 24th to 25th), which is extremely rare, historically speaking. According to the 500hpa circulation field during the high temperature process of July 10th–July 29th, the WPSH was particularly strong and moved northwestward as compared to the previous process. At that time, Zhejinag was located in the vicinity of the subtropical high, which led to the intense and long high temperature process.
Pages71
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/338269
Collection大气科学学院
Affiliation大气科学学院
First Author AffilicationCollege of Atmospheric Sciences
Recommended Citation
GB/T 7714
李琼. 浙江地区夏季高温气候特征及其影响因子研究[D]. 兰州. 兰州大学,2018.
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