我国首次在西风带海域进行密集观测

随着执行我中第25次南极考察任务的“雪龙”船进入西风带,本次考察一项重要的大洋科学项目“南印度洋XBT／XTCD走航观测”已逐渐展开：考察队将在西风带海域投放200多枚带有温度和盐度传感器的探头,这是我国南极考察首次在西风带海域进行如此密集的科学观测。     

中国海风能密度预报

利用NCEP预报风场,对2013年3月中旬发生在中国海的一次强冷空气过程进行分析,并利用预报风场计算得到这期间的风能密度,实现"风能密度数值预报",可为风电机采集风能提供日常保障,以提高装备的采集、转换效率。结果表明,1)NCEP预报风场可以很好地刻画冷空气给中国海带来的大风过程,从曲线走势、相关系数、偏差、均方根误差、平均绝对误差等分析也发现,NCEP预报风速在中国海具有很高精度。2)冷空气影响的海域,伴有明显的大风的过程,风能密度也出现明显的增幅。冷空气影响渤海时,该海域大部分区域的风速在10 m/s以上,大值中心在16 m/s以上;风能密度基本都在1 400 W/m2以上。冷空气影响的海域容易出现10 m/s以上的大风,对应区域的风能密度基本都在1 400 W/m2以上;冷空气的边缘海域风速也在8 m/s以上,风能密度在350 W/m2以上。3)利用NCEP预报风场,对海上风电场的风速、风能密度进行预报是可行的,可为风能开发、防灾减灾提供科学依据。     

20世纪80年代初以来北太平洋海温变化特征

应用1979.1-2006.12北太平洋海表温度（SST）资料,采用一元线性回归、功率谱等统计方法对该区SST的变化特征进行分析,结果表明：（1）北太平洋SST年际变化较为显著,尤其在靠近亚洲大陆一带洋面、北太平洋中部中纬度海域及赤道中、东太平洋;（2）北太平洋西部和中部SST1-12月均呈上升趋势,靠近亚洲大陆的日本海一带和我国大陆以东洋面升温最快。除我国以东洋面升温中心在冬季外,其余海域升温均在夏秋季更迅速,20世纪90年代初以来尤为明显;北美海岸山脉以西及赤道中、东太平洋SST则呈弱的下降趋势;（3）赤道中、东太平洋春夏季存在显著5a和3.5a左右的年际变化;北太平洋中部30°N一带冬春季存在5-6a左右的年际变化和约14a的年代际变化;（4）除北太平洋中部（西风漂流区）外,各个海域大部分月份SST高值年和低值年分别与厄尔尼诺年和拉尼娜年对应,西风漂流区SST高值年均出现在20世纪末21世纪初,低值年与厄尔尼诺年对应。     

不同海潮模型对GNSS站负荷位移计算的影响

基于古登堡平均地球模型和积分格林函数方法,利用中国近海海潮模型Chinasea 2010、Naoregional 1999和全球海潮模型EOT11a,计算中国沿海GNSS连续运行站上的海潮位移负荷影响,并对其均方根RMS及和方根RSS进行综合分析。结果表明,2种近海模型分潮波位移负荷差异水平分量大部分为亚mm级,垂直分量普遍为mm级,最大达5.8 mm;Chinasea 2010模型比Naoregional 1999模型在中国海域覆盖面积大,2种模型在黄海和东海海域差异较大,在渤海和南海海域差异较小;模型差异与测站位置及潮波频率均有关系,应比较观测资料的负荷改正效果,择优采用适宜本区域的模型。     

中国“科学”号科考船成功投放海底地震仪北大核心CSCD

任务的＂科学＂号科考船在既定区域首次投放1月19日,正在西太平洋雅浦海山海域执行科考7个海底地震仪。西太平洋是全球地质构造最活跃的区域。各国科学家对该海域马里亚纳岛弧研究较多,而雅浦海沟、卡罗琳海岭附近区域则鲜有研究。这次投放的海底地震仪,可持续记录卡罗琳洋脊俯冲系统的微震数据和全球5.5级以上的远震数据。     

利用JCZ-1T地震计BB通道观测数据检测地球自由振荡

采用库尔勒台JCZ-1T地震计BB通道垂直向的观测数据,利用功率谱密度估计方法,在没有对观测资料进行任何改正的情况下,获取2016-03-02印尼苏门答腊岛海域7.8级和2016-04-17厄瓜多尔7.5级大地震激发的0S7～0S60基频球型自由振荡,并与PREM模型理论值进行对比分析。结果表明,实测值与理论值相吻合,除部分振型与理论值偏差较大以外,其余振型与理论值偏差均小于0.1％。印尼苏门答腊岛海域7.8级地震所检测的球型振荡能量频谱分布及振型与厄瓜多尔7.5级地震所检测的球型振荡有一定差别,前者所能检测的振型数量相对较多。     

印度洋西北海域鸢乌贼9-10月栖息地适宜指数研究

印度洋西北部海域的鸢乌贼(Sthenoteuthis oualaniensis)具有一定的开发潜力,可作为商业性捕捞的对象,准确预报中心渔场可为指导生产提供依据。根据2003、2004年9～10月份期间我国鱿钓船在2°～24°N、57°～69°E海域的探捕数据,结合表温、盐度、海表面高度和叶绿素a,以CPUE作为适应性指数,利用算术平均法(AM)和几何平均法(GM)分别建立基于环境因子的综合栖息地指数模型。结果表明,9月份在栖息地指数(HSI)大于0.8的中心渔场作业次数比例超过24%,平均日产量在5.48 t/d左右;10月份在HSI大于0.8的中心渔场作业次数比例在43%以上,平均日产量在5.2 t/d以上。基于表温、盐度、海表面高度和叶绿素a的HSI模型能较好预测印度洋鸢乌贼中心渔场,且AM模型优于GM模型。     

几种全球加权平均温度模型的精度验证与分析

利用IGRA提供的全球593个无线电探空站2014年的探空资料,对Bevis 经验公式、GTm-Ⅱ和GTm-Ⅲ模型进行精度验证,对各模型随纬度、季节的变化规律进行分析研究。结果表明,在全球范围内,GTm-Ⅲ模型的总体精度（MAE=3.26 K, RMS=4.10 K）要优于另外两个模型;3种模型的精度在中低纬度地区较高,高纬度地区较低;Bevis公式和GTm-Ⅱ模型的精度在南北半球具有不对称性;各模型精度的季节性变化规律基本一致,模型的RMS在不同季节相差2~3 K。     

2020年全球鱿钓捕捞的时空特征分析

了解全球鱿钓捕捞的时空特征可为鱿鱼资源的评估与管理提供参考。本文选取2020年全球鱿钓船AIS轨迹数据与VIIRS夜间灯光影像,以FAO major Fishing Areas的19个海洋主要捕鱼区为捕捞分区依据,结合GIS空间分析方法开展了全球鱿钓捕捞的时空特征分析。结果表明：(1)鱿钓捕捞主要分布在西南大西洋阿根廷专属经济区周边、西北太平洋日本东北部远海、东南太平洋秘鲁西部远海、西北印度洋阿拉伯海以及中西太平洋阿拉弗拉海,集中在中、低纬度离陆地100 km以内和400～700 km范围内,呈现以条带式为主的分布模式;(2)全球鱿钓捕捞的时间规律表现出“两峰两谷”的变化态势,分别于1—4月、6—8月呈上升趋势,而在4—6月、8—12月呈下降趋势。中纬度的鱿钓捕捞于夏秋呈上升趋势,而在冬春呈下降趋势;低纬度的鱿钓捕捞在秋冬季节呈增加态势,而在春季呈减少态势;(3)鱿钓捕捞的时空特征受洋流、鱿鱼繁殖特性及各国远洋鱿钓政策影响,其空间分布走向与主要洋流流向一致,捕捞强度在鱿鱼产卵高峰期、休渔期时减弱;(4) AIS轨迹密度与夜间灯光亮度在鱿钓捕捞信号上有良好的时空相关性,AIS轨迹密度与夜...     

基于SRTM数据的广东新一代天气雷达覆盖研究

本文利用SRTM3高分辨率的数字高程模型（DEM）对广东省已建成的12部新一代天气雷达分别进行地形阻挡分析。结果表明,在低仰角（0.5°）的观测结果中,韶关、连州以及肇庆雷达受地形阻挡较严重,深圳、阳江、梅州和汕尾的雷达也有大面积阻挡区域,其余雷达的覆盖效果均很好。随着扫描仰角的抬高,地形对雷达波束的阻挡有所减弱。从第4个仰角 （3.4°）开始,所有雷达均无地形阻挡。在海拔5 km范围内12部雷达可以完全覆盖广东全省,大部分地区至少有4部雷达重叠。离地3 km和海拔3 km的雷达覆盖情况均显示,除广东省北部和西北部极少部分地区没有雷达覆盖外,大部分地区均有2部以上雷达覆盖,珠江三角洲入海口一带甚至有4~6部雷达重叠。在离地2 km范围内,广东省雷达组网能够有效覆盖广东省大部分区域。在离地1 km范围内,广东省北部和西北部雷达覆盖效果不太理想,存在较大的空白区。在离地高度2 km和海拔高度3 km以上,雷达组网基本可以覆盖广东全境,因此可以认为广东省雷达的总体布局较好。     

Southern ocean SST variability and its relationship with ENSO on inter-decadal time scales

Empirical orthogonal function (EOF) analysis reveals a co-variability of Sea surface temperatures (SSTs) in the Southern Hemisphere (0°-60°S). In the South Indian and Atlantic Oceans, there is a subtropical dipole pattern slanted in the southwest- north-east direction. In the South Pacific Ocean, a meridional tripole structure emerges, whose middle pole co-varies with the dipoles in the South Indian and Atlantic Oceans and is used in this study to track subtropical Pacific variability. The South Indian and Atlantic Ocean dipoles and the subtropical Pacific variability are phase-locked in austral summer. On the inter-decadal time scales, the dipoles in the South Indian and Atlantic Oceans weaken in amplitude after 1979/1980. No such weakening is found in the subtropical South Pacific Ocean. Interestingly, despite the reduced amplitude, the correlation of the Indian Ocean and Atlantic dipoles with El Nio and Southern Oscillation (ENSO) are enhanced after 1979/1980. The same increase in correlation is found for subtropical South Pacific variability after 1979/1980. These inter-decadal modulations imply that the Southern Hemisphere participates in part of the climate shift in the late 1970s. The correlation between Southern Hemisphere SST and ENSO reduces after 2000.     

Spatial-temporal variations of dominant drought/flood modes and the associated atmospheric circulation and ocean events in rainy season over the east of China

By using Season-reliant Empirical Orthogonal Function (S-EOF) analysis, three dominant modes of the spatial-temporal evolution of the drought/flood patterns in the rainy season over the east of China are revealed for the period of 1960-2004. The first two leading modes occur during the turnabout phase of El Nino-Southern Oscillation (ENSO) decaying year, but the drought/flood patterns in the rainy season over the east of China are different due to the role of the Indian Ocean (IO). The first leading mode appears closely correlated with the ENSO events. In the decaying year of El Nino, the associated western North Pacific (WNP) anticyclone located over the Philippine Sea persists from the previous winter to the next early summer, transports warm and moist air toward the southern Yangtze River in China, and leads to wet conditions over this entire region. Therefore, the precipitation anomaly in summer exhibits a ’Southern Flood and Northern Drought’ pattern over East China. On the other hand, the basin-wide Indian Ocean sea surface temperature anomaly (SSTA) plays a crucial role in prolonging the impact of ENSO on the second mode during the ENSO decaying summer. The Indian Ocean basin mode (IOBM) warming persists through summer and unleashes its influence, which forces a Matsuno-Gill pattern in the upper troposphere. Over the subtropical western North Pacific, an anomalous anticyclone forms in the lower troposphere. The southerlies on the northwest flank of this anticyclone increase the moisture transport onto central China, leading to abundant rainfall over the middle and lower reaches of the Yangtze River and Huaihe River valleys. The anomalous anticyclone causes dry conditions over South China and the South China Sea (SCS). The precipitation anomaly in summer exhibits a ’Northern Flood and Southern Drought’ pattern over East China. Therefore, besides the ENSO event the IOBM is an important factor to influence the drought/flood patterns in the rainy season over the east of China. The third mode is positively correlated with the tropical SSTA in the Indian Ocean from the spring of preceding year(-1) to the winter of following year(+1), but not related to the ENSO events. The positive SSTA in the South China Sea and the Philippine Sea persists from spring to autumn, leading to weak north-south and land-sea thermal contrasts, which may weaken the intensity of the East Asia summer monsoon. The weakened rainfall over the northern Indian monsoon region may link to the third spatial mode through the ’Silk Road’ teleconnection or a part of circumglobal teleconnection (CGT). The physical mechanisms that reveal these linkages remain elusive and invite further investigation.     

Statistical characteristics of austral summer cyclones in Southern Ocean

Characteristics of cyclones and explosively developing cyclones (or ’bombs’) over the Southern Ocean in austral summer (December, January and February) from 2004 to 2008 are analyzed by using the Final Analysis (FNL) data produced by the National Centers for Environmental Prediction (NCEP) of the United States. Statistical results show that both cyclones and explosively developing cyclones frequently develop in January, and most of them occur within the latitudinal zone between 55°S and 70°S. These cyclones gradually approach the Antarctic Continent from December to February. Generally cyclones and bombs move east-southeastward with some exceptions of northeastward movement. The lifetime of cyclones is around 2-6 d, and the horizontal scale is about 1000 km. Explosive cyclones have the lifetime of about 1 week with the horizontal scale reaching up to 3000 km. Compared with cyclones developed in the Northern Hemisphere, cyclones over the southern ocean have much higher occurrence frequency, lower central pressure and larger horizontal scale, which may be caused by the unique geographical features of the Southern Hemisphere.     

Definition of the South China Sea summer monsoon onset

We analyze statistically different definitions of the South China Sea summer monsoon (SCSSM) onset are to establish a SCSSM onset time series that is more recognizable by a majority of indicators. With the acknowledged index, we determine a key area (105°E–112.5°E, 7.5°N–12.5°N) and define the zonal wind component in this key area as a new SCSSM onset index, using daily mean reanalysis data of the National Center for Environmental Prediction/National Center for Atmospheric Research. The atmospheric circulations before and after the onset of the SCSSM determined using the index defined in this paper are preliminarily studied. Results show that the Somalia cross-equatorial flow is enhanced, the strongest westerly wind in the tropical Indian Ocean shifts northward, the cyclone couple in the Bay of Bengal and the Southern Hemisphere weaken and move eastward, convection over the South China Sea increases, and the subtropical high retreats from the South China Sea after the outbreak of the SCSSM. By analyzing the atmospheric circulation, it is found that in 1984 and 1999, the SCSSM broke out in pentads 29 and 23, respectively, which is consistent with the onset times determined using our index.     

Global distribution of thermosteric contribution to sea level rising trend

The sea level derived from TOPEX/Poseidon(T/P) altimetry data shows prominent long term trend and inter-annual variability.The global mean sea level rising rate during 1993-2003 was 2.9 mm a-1.The T/P sea level trend maps the geographical variability.In the Northern Hemisphere(15°-64°N),the sea level rise is very fast at the mid-latitude(20°-40°N) but much slower at the high-latitude,for example,only 0.5 mm a-1 in the latitude band 40°-50°N.In the Southern Hemisphere,the sea level shows high rising rate both in mid-latitude and high-latitude areas,for example,5.1 mm a-1 in the band 40°-50°S.The global thermosteric sea level(TSL) derived from Ishii temperature data was rising during 1993-2003 at a rate of 1.2 mm a-1 and accounted for more than 40% of the global T/P sea level rise.The contributions of the TSL distribution are not spatially uniform;for instance,the percentage is 67% for the Northern Hemisphere and only 29% for the Southern Hemisphere(15°-64°S) and the maximum thermosteric contribution appears in the Pacific Ocean,which contributes more than 60% of the global TSL.The sea level change trend in tropical ocean is mainly caused by the thermosteric effect,which is different from the case of seasonal variability in this area.The TSL variability dominates the T/P sea level rise in the North Atlantic,but it is small in other areas,and shows negative trend at the high-latitude area(40°-60°N,and 50°-60°S).The global TSL during 1945-2003 showed obvious rising trend with the rate of about 0.3 mm a-1 and striking inter-annual and decadal variability with period of 20 years.In the past 60 years,the Atlantic TSL was rising continuously and remarkably,contributing 38% to the global TSL rising.The TSL in the Pacific and Indian Ocean rose with significant inter-annual and decadal variability.The first EOF mode of the global TSL from Ishii temperature data was the ENSO mode in which the time series of the first mode showed steady rising trend.Among the three oceans,the first mode of the Pacific TSL presented the ENSO mode;there was relatively steady rising trend in the Atlantic Ocean,and no dominant mode in the Indian Ocean.     

Sea Salt Sodium Record in a Shallow Ice Core from East Antarctica as a Potential Proxy of the Antarctic Sea Ice Extent in Southern Indian Ocean

Antarctic sea ice has experienced an increasing trend in recent decades, especially in the Ross Sea and Indian Ocean sectors. Sea ice variability affects greatly the maritime airmass transport from high latitude to Antarctic continent. Here we present a new ice core record of sea salt sodium(ssNa+) concentration at annual-resolution in the Princess Elizabeth Land spanning from 1990 to 2016, showing that this marker could be used as a potential proxy for reconstructing the sea ice extent(SIE) in the Southern Indian Ocean(SIO) given their significant correlation(R =-0.6, P 0.01) over the past 27 years. The correlation and composite analyses results show that the ssNa~+ at the 202 km inland from Zhongshan Station and the SIE changes in SIO are closely related to the Indian Ocean Dipole(IOD) and Southern Annular Mode(SAM). The northward wind in central SIO occurs during positive IOD and the strengthened westerlies occurs during positive SAM, both of which favor increased sea ice in SIO and lead to the decreased ssNa~+ concentration at the coastal site.     

Bacterial productivity in the Prydz Bay and its adjacent waters,Antarctic

1　IntroductionBacteriaandtheiractivitiesplayanimportantroleintheelementalbiogeochemicalcyclesandenergytransformingintheocean (Zhenetal.1 997) .DortchandPackard(1 989) proposedthatfoodwebsintheeutrophicwatersaredominatedbythebiomassofprimaryproducerswhilefoodwebsintheoligotrophicwatersaredominatedbythebiomassofmicrobes.Heterotrophicbacteriahadbeenshowntoplayanimportantroleinthedecompositionoflarge ,rapidlysinkingorganicparticleswithinandbelowtheeuphot iczone ,andfurthertoaffecttheelementaldyn…     

“海上丝绸之路”主要海域热带气旋时空分布特征及其危险性

热带气旋作为一种海上灾害性天气,对“海上丝绸之路”海上航运影响重大。本文基于西北太平洋和北印度洋1990—2017年的热带气旋路径数据,结合热带气旋风场参数模型,利用缓冲区分析、叠加分析等GIS空间分析技术,系统研究了“海上丝绸之路”主要海域、主要海区、关键通道受热带气旋影响频次以及热带气旋危险性的时空分布特征。主要结论：① “海上丝绸之路”主要海域受热带气旋影响严重,表现在热带气旋影响范围广、影响频次高,其中西北太平洋较北印度洋受热带气旋影响更为严重,危险性更大;② 西北太平洋的15°N—30°N,120°E-—145°E海域热带气旋危险性最高;③ 热带气旋危险性季节变化较为明显,秋夏两季危险性较高,冬春两季危险性较低,在夏秋两季各月份中,7、8、9、10月危险最高;④ 在各海区中,中国东部海区热带气旋危险最高,其次是南海、日本海、孟加拉湾、阿拉伯海,而红海和波斯湾不受热带气旋影响;在各关键通道中,吕宋海峡热带气旋危险性最高,其次是台湾海峡、对马海峡、宗谷海峡、鞑靼海峡、保克海峡、霍尔木兹海峡,而马六甲海峡和曼德海峡无热带气旋危险。     

The modeled atmospheric and oceanic response to the South China Sea SST anomaly

The sensitivity of the global atmospheric and oceanic response to sea surface temperature anomaly (SSTA) throughout the South China Sea (SCS) is investigated using the Fast Ocean-Atmosphere Model (FOAM). Forced by a warming SST, the experiment explicitly demonstrates that the responses of surface air temperature (SAT) and SST exhibit positive anomalous center over SCS and negative anomalous center over the Northern Pacific Ocean (NPO). The atmospheric response to the warm SST anomalies is characterized by a barotropical anomaly in middle-latitude, leading to a weak subtropical high in summer and a weak Aleutian low in winter. Accordingly, Indian monsoon and eastern Asian monsoon strengthen in summer but weaken in winter as a result of wind convergence owing to the warm SST. It is worth noting that the abnormal signals propagate poleward and eastward away in the form of Rossby Waves from the forcing region, which induces high pressure anomaly. Owing to action of the wind-driven circulation, an anomalous anti-cyclonic circulation is induced with a primary southward current in the upper ocean. An obvious cooling appears over the North Pacific, which can be explained by anomalous meridional cold advection and mixing as shown in the analysises of heat budget and other factors that affect SST.