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题名:
中国沿海极端气候变化及其对NDVI的影响特征研究
作者: 王晓利1,2
学位类别: 博士
答辩日期: 2017-05-21
授予单位: 中国科学院大学
授予地点: 北京
导师: 侯西勇
关键词: 极端气温事件 ; 极端降水事件 ; NDVI ; 时空变化 ; 区域差异 ; 中国沿海
学科分类: 环境科学技术::环境科学技术基础学科::环境科学技术基础学科其他学科
中文摘要:
    在全球气候变化的背景下,极端气候事件频繁发生。与气候平均态的变化相比,极端气候的变化对社会经济发展和生态环境演变的影响更显著、更强烈。中国沿海地区是一个生态脆弱性较高的地区,对气候变化极其敏感,该区域台风、风暴潮、暴雨、热浪以及干旱等极端天气气候事件频繁发生,造成海平面上升、海水入侵、城市内涝、农业和渔业减产减收等严重后果,直接影响区域社会经济的可持续发展,对生态环境保护和人们的生产生活构成了严重威胁和巨大挑战。
    植被覆盖在中国沿海地区的生态服务功能中扮演了极其重要的角色。近年来,高温热浪、强降水和干旱等极端气候事件的变化对沿海地区的植被覆盖产生了一定程度的影响,造成区域初级净生产力、水土保持、大气调节、气候维持乃至整个生态系统产生一定的变化。鉴于此,研究沿海地区极端气候事件的历史变化特征、空间差异特征以及未来变化趋势,并进一步探究极端气候事件对植被覆盖的影响作用,不仅有益于促进区域生态环境保护和生态建设成果的维持,而且能够为中国沿海区域经济可持续发展决策提供强有力的支持。
    本文基于1961~2014年中国沿海地区地面气象站的逐日平均气温、日最高(低)气温以及逐日降水资料,计算27个极端气温和极端降水指数,对沿海地区及各子区域极端气候事件的变化趋势及其持续性、周期特征、突变特征、空间格局等进行全面和深入的分析;同时,基于GIMMS NDVI3g数据分析1982~2014年中国沿海地区NDVI的时间变化趋势及其持续性、突变特征以及空间分布特征等;最后,利用相关性分析和去季节变化方法探究中国沿海地区极端气候事件对NDVI的影响特征。本文的主要结论如下:
(1) 极端气温事件特征
    中国沿海及各子区域极端气温暖指数呈上升趋势,冷指数和气温日较差呈下降趋势,夜指数的变化幅度明显大于昼指数的变化幅度。相对指数、极高值指数和冷(暖)持续日数的多年均值在各子区域之间相差不大,霜冻日数、冰冻日数和气温日较差的多年均值从北至南依次递减,夏季日数、热夜日数、极低值指数和生长季长度的多年均值从北至南依次增加。各子区域极端气温指数年际间的主周期介于2~8 a。各子区域极端气温指数的突变主要发生在1980s和1990s,冷指数和极低值指数的突变时间稍早于暖指数和极高值指数的突变时间。未来一段时期,沿海地区极端气温事件仍继续呈上升趋势,极端低温事件会继续下降。极端气温暖(冷)指数对日均气温和日最高(低)气温具有较好的指示性,而气温日较差、日最高气温的极低值和冰冻日数等对均态气温的指示性相对较弱。
(2) 极端降水事件特征
   中国沿海地区及各子区域的持续湿润日数呈下降趋势,其他极端降水指数在黄淮(含)以北基本呈下降趋势,以南呈上升趋势,在全区表现为增加趋势。极端降水指数的多年均值基本呈北低南高的分布状态,最高值和最低值一般分别在华南和华北沿海地区。各子区域极端降水指数的主周期介于2~7 a之间。极端降水指数的突变主要发生在1990s和1970s,突变后,东北和江淮(含)以南沿海地区的极端降水日趋频繁,华北和黄淮沿海地区极端降水日趋减少。未来时期,华北、黄淮和江淮沿海地区将趋于干旱化,而东北、江南和华南沿海地区极端降水事件将持续增多。除持续干燥日数以外,其他极端降水指数两两之间高度相关,对年总降水量的指示性均较强。
(3) 极端气候对植被覆盖的影响特征
    中国沿海地区及各子区域的NDVI均呈上升趋势,未来时期该趋势仍将持续。各子区域NDVI的突变主要发生在21st初期,其次是1990s,突变后,区域植被指数呈增加趋势。沿海地区植被覆盖状况总体较好,江淮(含)以南沿海地区的覆被状况优于江淮以北的。
   年际尺度上,极端气温暖指数和极值指数与NDVI总体呈正相关,气温日较差在黄淮(含)以北与NDVI呈负相关,在黄淮以南呈正相关;黄淮(含)以北沿海地区极端降水量与NDVI基本呈正相关。年内尺度上,极端气温极值指数和气温日较差与NDVI之间均呈强相关关系,江南(含)以南沿海地区的NDVI对极端气温极值指数存在一定的时滞现象;江淮(含)以北沿海地区年内极端降水与NDVI总体呈正相关,江淮以南NDVI对极端降水具有一定的滞后性。极端高温类指数和气温日较差均对东北沿海西部、华北沿海和黄淮沿海地区的NDVI产生负面影响,对其他沿海地区的NDVI产生正面影响,当月和前一个月极端低温类指数对沿海地区的NDVI总体上分别起消极和积极影响;极端降水对东北沿海西部、华北和黄淮沿海地区的NDVI起积极影响作用,对其他沿海地区的NDVI均起消极影响作用。
   本研究评估了中国沿海地区极端气温事件和极端降水事件的时空变化特征,并着重开展区域差异特征的比较研究,同时,结合沿海地区NDVI数据,进一步评价了极端气温事件和极端降水事件对NDVI的影响特征,以更好地认识沿海地区极端气温事件和极端降水事件的变化特征和规律及其对NDVI的影响,为科学适应、减缓和应对沿海地区气候异常和海岸带生态环境保护提供参考和依据,促进沿海地区社会经济和生态环境的可持续发展。
英文摘要:
    Within the context of climate change, extreme climate events have accurred frequently. Extreme climate events have more significant and stronger impact than average state on social-economic development and ecological environment evolution. The coastal area of China is a region with high ecological vulnerability and is extremely sensitive to global climate change. Extreme climate events such as typhoon, strom surge, heavy rain, heat waves and drought occur frequently in the coastal area of China, resulting in grave consequences in term of sea level rise, sea water intrusion, urban waterlogging, reduction of agricultural and sideline production and so on, affect the regional socio-economic sustainable development directly, which poses a huge challenge and a serious threat to the ecological and environment protection and people’s living conditions.
Vegetation cover plays an important role in the ecological service function over the coastal area of China. Recently, extreme climate events such as high temperature and heatwave, heavy precipitation and drought have had a certain degree of impact on vegetation cover over the coastal areas, which lead to the change of regional primary net productivity, soil and water conservation, atmospheric regulation, climate maintenance and stability of the entire ecosystem. Given this, conducting research on characteristics of historical changes and its persistence, spatial differences and consistency with climate average state of extreme climate events, and explore the impact of extreme climate events on vegetation cover further are important precequisite for assessing the impact change on the ecological environment and social environmental over the coastal areas, which contributes to promoting regional ecological and environmental protection and ecological costruction preserve, and providing strong support for the decision-making of sustainable development of economy and society.
    Based on daily temperature and precipitation dataset of 156 weather station records from 1961 to 2014 in the coastal area of China, 27 extreme temperature and extreme precipitation indices were calculated, and then the extreme climate events’ characteristics on terms of change trend and its persistence, periodicity, abruptness and spatial pattern were investigated comprehensively and thoroughly using a set of mathematical and statistical methods including trend analysis, Morlet analysis, Mann-Kendall test, accumulative anomaly analysis, Pettitt test, principal component analysis and correlation analysis. Additionally, based on GIMMS NDVI3g data, the temporal trends and its persistence, abrupt characteristics and spatial distribution of NDVI in the coastal area of China from 1982 to 2014 were analyzed. Finally, the impact of extreme climate events on NDVI were explored in the coastal area of China by employing correlation analysis and de-seasonalization methods. The main conclusions of this paper are as follows:
(1) Extreme temperature events characteristics
    An upward trend in warm extremes and a downward trend in cold extremes as well as diurnal temperature range (DTR) were found, and the decadal trend rates of the night extremes were obviously higher than those of the day extremes in the coastal area of China and its sub-regions. Generally, a decrease was observed in the multi-year averages of the frost days (FD0), ice days (ID0) and diurnal temperature range (DTR), and an increase was observed in the mutil-year averages of the summer days (SU25), tropical nights (TR20), minimum value of daily maximum temperature (TNx), minimum value of daily minimum temperature (TNn) and growing season length (GSL) from north to south. However, a little variation was observed in the multi-year averages of the cool days (TX10p), cool nights (TN10p), warm days (TX90p), warm nights (TN90p), maximum value of daily maximum temperature (TXx), maximum value of daily minimum temperature (TNx), cold spell duration index (CSDI) and warm spell duration index (WSDI) between the sub-regions and the entire coastal area of China. Primary period of extreme temperature indices varied from 2- to 8-year in the sub-regions. The mutation time of extreme temperature indices occurred mainly in the 1980s and the 1990s in all sub-regions. Additionally, the cold extremes and minimum values of daily maximum (minimum) temperature mutated earlier than those of the warm extremes and maximum values of daily maximum (minimum) temperature. In the coming period, the change trends of the extreme warm and extreme cold indices will continue as the trends of the past, respectively. Extreme temperature warm (cold) indices both exhibited high contributions to the daily average and daily maximum (minimum) temperatures. DTR, TNx and so on showed a weak indicative to the daily average and daily maximum (minimum) temperatures.
(2) Extreme precipitation events characteristics
    Except consecutive moisture days (CWD) showed a downward trend over the coastal area of China and its sub-regions, there was a generally insignificant upward and downward tendency of other all extreme precipitation indices in the southern and in the northern coastal area, respectively, and an upward trend in the entrie coastal area. Multi-year averages of all extreme precipitation indices except consecutive dry days (CDD) varied largely in the coastal area of China, generally highest in the Huanan coastal area and lowest in the Huabei coastal area, respectively. Primary period of extreme precipitation indices varied from 2- to 7-year in the sub-regions. The abrupt change of extreme precipitation indices occurred mainly in the 1990s and the 1970s in the sub-regions. Extreme precipitation events in the Dongbei and the south of Jianghuai (inclusive) coastal areas tended to be more frequency while in the Huabei and Huanghuai coastal areas were decreasing after mutation. Sub-regions of Huabei, Huanghuai and Jianghuai coastal areas would be suffering from drought but Dongbei, Jiangnan and Huanan coastal areas would be much moist in the future. Except CDD, the other extreme precipitation indices correlated strongly with each other, and exhibited high contributions to the annual total precipitation amount.
(3) Impact of extreme climate events on NDVI
    The tendency of NDVI in the coastal area of China and its sub-regions showed an upward trend and would be increasing in the coming period. NDVI series in sub-regions got a mutation mainly in the early 21st, followed by the 1990s, and an increasing trend was found after mutation in each sub-region. The vegetation coverage was generally good in the coastal area of China, and the coverage in the south of Jianghuai coastal area (inclusive) was much better than that in the north.
    On the interannual scale, the warm extremes and extreme value indices showd a positive correlation with NDVI in the CAC, and DTR showed a negative correlation with NDVI in the north of Huanghuai coastal area (inclusive) but a positive correlation in the south’s. Exreme preciptiaiton events presented a positive correlation with NDVI in the north of Huanghuai coastal area (inclusive). The extreme value indices and DTR both correltated with NDVI strongly on the scale of the year, and NDVI in the Jiangnan coastal area (inclusive) showed a lag effect on the extreme value indices. Extreme preciptiaiton events in the north of Jianghuai coastal area presented a positive correlation with NDVI generally and NDVI in the south of Jianghuai coastal area (inclusive) showed a lag effect on the extreme precipitation events. Extreme high temperature indices and DTR both showed a negative effect on the NDVI in the western of Dongbei coastal area, Huabei and Huanghuai coasta area while a positive effect in the other coastal areas. The current month and the preceding month exhibited a negative and a positive effect on the NDVI in the CAC, respectively. Extreme precipitation indices affected the NDVI in the werstern of Dongbei coastal area, Huabei and Huanghuai coastal areas positively, while in the other coastal areas negatively.
    The spatiotemporal variations of extreme climate events and their impacts on NDVI in the coastal area of China were revealed in this paper could privide reference and basis for scientific adaptation, mitigation and response to climate anomalies and coastal zone ecological and environment protection, which were beneficial to the sustainable development of social economy and ecological environment in the coastal area of China.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.yic.ac.cn/handle/133337/21998
Appears in Collections:中科院烟台海岸带研究所知识产出_学位论文

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作者单位: 1.中国科学院烟台海岸带研究所
2.中国科学院大学

Recommended Citation:
王晓利. 中国沿海极端气候变化及其对NDVI的影响特征研究[D]. 北京. 中国科学院大学. 2017.
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