白令海及楚科奇海夏季水文结构年际变化特征研究

发布时间：2017-12-27 10:25

本文关键词：白令海及楚科奇海夏季水文结构年际变化特征研究　出处：《上海海洋大学》2016年硕士论文　论文类型：学位论文

【摘要】：北极是地球的冷源,在全球气候系统中起着重要的调节作用。北极气候在过去30多年正在发生快速变化,影响着全球尤其是北半球的环境和气候。我国自1999年实施首次北极科学考察以来,已完成了4个航次的北极科考,获取大批有价值的科考数据。作为历年北极科考重点海域的白令海与楚科奇海在地球气候系统演变过程中有着相当重要的作用。本文以白令海和楚科奇海的夏季水文结构年际变化为重点展开研究,主要解决了以下问题:一是基于2008年、2010年、2012年和2014年我国北极科学考察期间在白令海获取的水文观测数据,通过对白令海B断面温盐、水团、上层海洋的热含量分布进行分析,探讨了白令海水文结构的年际变化特征。结果表明,(1)白令海夏季的水团包括白令海上层水团(BUW),中层水团(BIW)、深层水团(BDW)和白令海陆架水团(BSW)。(2)白令海温盐分布差异最大、年际变化最剧烈的主要集中在上层水团。(3)对比四年水团分布情况,最明显的变化是2012年7月调查区上层水温度偏低,2014年7月上层海水温度偏高,该年白令海冬季残留水较其他年份浅50—70m。(4)这种异常变化在热含量方面表现为,2012年7月调查区各个测站上的热含量异常低,而2014年7月测站上的热含量都高于平均水平。二是结合历史共享资料,分析了白令海2008年、2010年、2012年及2014年7月净热通量变化、风场及海平面气压分布等天气特征,着重研究了2014年7月海温偏高原因。结果表明,(1)夏季白令海整个海区都是获得热量的,大部分区域的净热通量在160~240 W·m~(-2)之间。(2)2014年7月白令海表层温度偏高在陆架和海盆区分别为两种不同的形成机制。陆架区主要是因为累积净热通量偏高,海水吸收热量升温造成;5~7月累积热通量的偏高造成了2014年7月白令海陆架区海表温度偏高。热通量的变化对白令海海盆夏季水温异常变化的贡献不大,但是对陆架区有显著的影响。(3)白令海2014年7月海盆区海温偏暖是由于异常强且持久的海平面高压以及负的风应力旋度风场的共同作用。2014年5~7月,白令海海盆区异常强的海平面高压一方面使得其西侧的测站持续以偏南风主导,将南方的暖水输送到该区,加上累积净热通量的共同作用加热表层海水;另一方面,使负的风应力旋度加强,即白令海上层海洋的反气旋式环流增强,表层暖水通过Ekman抽吸辐合下沉加热下层海水,造成该区冬季残留水偏暖。三是基于2008年、2010年、2012年和2014年我国北极科学考察期间在楚科奇海获取的水文观测数据,分析了楚科奇海C、R及SR断面温盐分布与年际变化。结果表明,(1)C断面温盐最突出的特征是:西部低温高盐,东部高温低盐。其中最南的C1断面在167.5°W附近有显著的温盐锋面;北边的C2断面与南部断面相比,整体温度降低;层化显著,在断面西侧有温度低于0°C的冷水。再向北C3断面,温盐层化显著,底层出现温度低于-1°C的高盐水体。(2)R断面的考察时间早过SR断面1个月左右,比较温盐变化,发现回程观测到的表层水温大于去程观测的温度1℃左右;盐度差异比温度差别更大,回程观测结果显示表层有淡盐水从表层向深层扩散,深层水盐度整体下降约1.5psu。四是系统分析了2008年、2010年、2012年及2014年北极科考调查区楚科奇海的表层温盐分布、水团年际变化。结果表明,(1)楚科奇海表层海水温度自南向北逐渐减小,东岸即阿拉斯加沿岸海域Hope角温度要大于中部1~2℃,盐度低于附近其他区域盐度。(2)楚科奇海夏季水团包括阿拉斯加沿岸水(ACW)、太平洋冬季水(PWW)、季节性冰融水(SMW)、大西洋水(AW)和楚科奇海夏季水(CSW)五种水体。其中,本文以-1.6℃为界将PWW细分为:新太平洋冬季水(NPWW)和冬季残留水(RPWW);以-1.0℃为界将SMW细分为:早期季节性冰融水(ESMW)接近冰点和晚期季节性冰融水(LSMW)。(3)楚科奇海表层温盐存在明显的时空变化。在太平洋水沿楚科奇海东部向北运动的过程中,表层水受融冰的影响,盐度逐步降低,ACW与CSW相互作用,ACW范围增大。PWW在2012年范围最大,2014年调查期未观测到PWW水团。
[Abstract]:The Arctic is the cold source of the earth and plays an important role in the global climate system. The Arctic climate has been changing rapidly over the past 30 years, affecting the global environment and climate in the northern hemisphere, especially in the northern hemisphere. Since the implementation of the first Arctic scientific expedition in 1999, China has completed 4 voyages of the Arctic science examination to obtain a large number of valuable scientific data. As the key areas of the Arctic expedition of the Bering Sea and the Chukotka sea in the process of evolution of the earth's climate system plays an important role. In this paper, the summer hydrological structure the interannual variation of the Bering Sea and the Chukotka sea as the focus of research, mainly to solve the following problems: one is the observed hydrological data acquisition in the Bering Sea during 2008, 2010, 2012 and 2014 China's Arctic expedition based on through the heat content on the B section, the sea temperature and salinity, the upper ocean water masses the distribution is analyzed, to investigate the interannual variation of the structure of the Bering sea. The results show that (1) water masses in the Bering Sea in the summer of the Bering Sea water layer (BUW), intermediate water (BIW) and deep water (BDW) and the Bering Sea shelf water (BSW). (2) the Heuli distribution biggest difference and interannual variation of the most intense mainly concentrated in the upper water masses. (3) comparison of the four water distribution, the most obvious change is the low temperature upper water survey area in July 2014 July 2012, the upper water temperature is high, the Bering Sea in winter residual water than other years shallow 50 - 70m. (4) the abnormal change is shown in the aspect of heat content. The heat content of each station in July 2012 is extremely low, while the heat content in July 2014 is higher than the average level. Two, combined with historical shared data, we analyzed the characteristics of the net heat flux, the wind field and the sea level pressure distribution in the Bering Sea in 2008, 2010, 2012 and July 2014, and emphatically studied the reasons for the high sea surface temperature in July 2014. The results showed that (1) the whole sea area in the Bering Sea was obtained heat in summer, and the net heat flux in most areas was between 160~240 W m~ (-2). (2) the high surface temperature in the Bering Sea in July 2014 was two different formation mechanisms in the continental shelf and the basin. The continental shelf is mainly due to the high accumulation net heat flux and the absorption of heat by seawater. The high accumulated heat flux in 5~7 month caused the high sea surface temperature in the Bering Sea shelf area in July 2014. The change of heat flux has little contribution to the abnormal change of water temperature in the Bering Sea Basin in summer, but it has a significant influence on the shelf area. (3) the Bering Sea basin warm SST in July 2014 is due to the abnormal strong and persistent sea-level pressure and negative wind common action of stress curl wind field. 2014 5~7 months, the Bering Sea basin is strong high sea level on the west side of the station to continue its southerly warm water delivery will be dominant, South to the area, plus the cumulative net heat flux interaction of heating surface water; on the other hand, the negative wind stress curl strengthening namely, anti cyclonic circulation in the Bering Sea upper ocean enhanced surface warm water through the Ekman suction convergence caused by the heat sink lower water, winter warm water residue. Three is the hydrological observation data acquisition in the Chukotka sea during 2008, 2010, 2012 and 2014 China's Arctic expedition on the basis of the analysis of C, R and SR section thermohaline distribution and interannual variation of the sea of Chukotka. The results show that (1) the most prominent characteristics of the temperature and salt in the C section are low temperature and high salt in the West and high temperature and low salt in the East. The most southern C1 section has a significant temperature and salinity front near 167.5 degree W. The C2 section on the north side is lower than the southern section, and the overall temperature is reduced. The stratification is significant, and there is cold water below 0 degrees C on the west side of the section. North section of C3, temperature and salt significantly, underlying the emergence of high salt water temperature lower than -1 DEG C. (2) the effect of time earlier than the R section of the SR section for about 1 months, compared the temperature and salinity of the surface water temperature, found that the observed return to process greater than the observed temperature is about 1 DEG C; the salinity difference is much larger than the temperature difference, the observation results show the surface return light salt water from the surface to the deep salinity diffusion, deep the overall water decreased by about 1.5psu. The four is the system analysis in 2008, 2010, 2012 and 2014, the Arctic expedition survey area of Chukotka sea surface temperature and salinity distribution, interannual variation of water. The results show that (1) Chukotka sea surface water temperature gradually decreased from the south to the north, the east coast of Alaska coastal waters Hope angle is greater than the central temperature of 1~2 DEG C, the salinity is lower than that of other regions near the salinity. (2) the Chukotka sea in the summer water including Alaska coastal water (ACW), Pacific winter water (PWW), seasonal ice water (SMW), the Atlantic (AW) and the Chukotka sea in the summer of five water water (CSW). In this paper, based on the boundary of -1.6 C, PWW is subdivided into: new Pacific winter water (NPWW) and winter residual water (RPWW). At -1.0 C level, SMW is divided into: early seasonal ice melt water (ESMW), near freezing point and late seasonal ice melt water (LSMW). (3) significant spatio-temporal variation of Chukotka sea surface temperature and salt. In the process of sea water along the Pacific Chukotka northward movement, the surface water is affected by ice melting, salinity gradually reduced, ACW interacts with CSW and ACW increase. PWW in 2012 2014 the largest scope survey period was observed in PWW water.
【学位授予单位】：上海海洋大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P731

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