2000—2015年华北地区8月极端干旱的异常环流型及其波活动特征          下载免费PDF全文

徐玮平  孟祥新  伯忠凯  邢雅敏 《山东气象》2021,41(1):92-99

利用1961—2015年华北地区54个国家级气象观测站夏季8月逐日降水资料和2000—2015年欧洲中期天气预报中心(ECMWF)再分析数据,研究了华北地区8月极端干旱的异常环流型及原因。结果表明:华北地区极端干旱事件以年际变化为主,2000—2015年华北地区极端干旱年在中高纬500 hPa高度距平场上存在“-、+、-、+”的异常波列结构,乌拉尔山西部地区上空存在较强的反气旋性距平使得暖脊加强向北收缩,同时贝加尔湖上空存在较强的反气旋性距平使得此处的高空脊强度异常加强,影响范围加大,这种异常环流形势导致高空脊前干冷西北气流输送到华北地区。欧洲西部地区是北半球中高纬波作用通量的关键区,该地区地表2 m温度呈明显增加趋势,同时该关键区对应的500 hPa垂直波作用通量TNZ也呈现明显增加趋势。由于异常热力强迫作用激发出EU波列,低层能量向上传输,高层能量向外频散影响下游乌拉尔山西部地区暖脊加强,造成中高纬环流异常,导致华北地区极端干旱事件频发。  相似文献   

Vertical flux of particulate organic carbon in the central South China Sea estimated from 234Th-238U disequilibria     

马豪  曾志  何建华  陈立奇  尹明端  曾实  曾文义 《中国海洋湖沼学报》2008,26(4)

234Th-238u disequilibria were applied to examine the particle dynamics in the euphotic zone of the central South China Sea during the spring 2002 cruise. The particulate organic carbon (POC), 234Th (including both dissolved and particulate) and 238U in the water column at three stations were determined. The profiles of 234Th/238U activity ratio at the three stations all showed consistent 234Th deficit as compared to 238U in the upper 100 m water column. Based on the profiles of the dissolved and particulate 234Th and a steady state box model, the dissolved 234Th scavenging rates, the particulate 234Th removal rates and their resident times were quantified. It was found that the POC downward export fluxes out of the upper 100 m euphotic zone ranged from 9.40 to 14.78 mmol.m-2.d-1. The results from this study provide new information for our understanding of carbon biogeochemical cycle in the South China Sea.  相似文献   

浅水刺参养殖池塘两种底质中微藻形态功能群及其密度影响因素          下载免费PDF全文

石楷  王敏  邢荣莲  曹学彬  姜爱莉 《应用海洋学学报》2020,39(3):329-338

为探究藻类形态功能群(Morphologically Based Functional Group,MBFG)在浅水刺参(Apostichopus japonicus)养殖池塘表层底质中的应用以及主要微藻类群密度变化规律,将形态功能群归类方法与冗余分析(Redundancy Analysis,RDA)相结合对刺参养殖池塘两种类型表层底质(泥沙底质和淤泥底质)中的微藻类群形态功能群构成以及主要功能群密度与水温及营养盐的相关性进行分析。结果表明,两种底质中微藻类群仅归为两个形态功能群,分别为形态功能群Ⅴ和Ⅵ,其中形态功能群Ⅵ即硅藻类各月密度较大且与形态功能群Ⅴ差异极显著(p 0. 01);泥沙底质和淤泥底质中硅藻密度分别在9月[(700±17) cells/cm3)]和8月[(580±12) cells/cm3]达到峰值,两池塘上层底质(0～2 cm)中硅藻的密度分别为下层底质(3～5 cm)的3倍(泥沙底质)、25倍(淤泥底质);冗余分析结果显示,活性硅酸盐浓度与水温分别是影响泥沙底质和淤泥底质中藻类形态功能群Ⅵ密度的首要因素。研究表明,刺参养殖池塘表层底质中微藻种类较少;在浅水刺参养殖池塘表层底质中可应用形态功能群归类方法对微藻类群进行聚类,结合冗余分析研究主要功能群密度的变化规律。养殖时应根据池塘底质类型差异制定相应管理和养护方法。  相似文献   

《海洋地质与第四纪地质》2012年第3期题目预告     

《海洋地质与第四纪地质》2012,(2):168

  相似文献   

Distribution and fluxes of suspended sediments in the offshore waters of the Changjiang (Yangtze) Estuary     

WAN Xinning  LI Jiuf  SHEN Huanting 《海洋学报(英文版)》2009,28(4):86-95

The offshore waters of the Changjiang Estuary are the transitional areas where river-supplied water and sediment are transported to the sea, and material exchanges occur with the neighbored Hangzhou Bay and the Jiangsu waters. Field observations of currents and sediment properties were conducted to study temporal and spatial distributions of suspended sediments under various dynamical conditions. The high sediment concentrations were found to occur in the western and southern waters of the offshore, and the low concentrations occurred in the eastern and northern waters. This pattern of the suspended sediment concentration (SSC) distribution is obviously influenced by the runoff and tidal current. The significant difference of along-estuary SSC distribution indicates that the SSC is reduced gradually from the west to the east, and that in the spring tide is obviously higher than in the neap tide. The methods of mechanism analysis and equal-area grids were used to calculate the suspended sediment fluxes at the typical cross sections. It was found that 44 percent of total suspended sediments from the Changjiang River were deposited in the submarine delta, and more than 27 percent of sediments were transported southernly into the Hangzhou Bay, and only 9 percent of sediments was supplied and exchanged with the northern Jiangsu waters, and about 20 percent of sediments was delivered offshore to the sea.  相似文献   

硇洲岛海域文昌鱼的分布与栖息地底质关系     

卢伙胜  周林滨  颜云榕  冯波 《台湾海峡》2009,28(2):272-278

为研究清楚南海硇洲岛海域文昌鱼分布的底质环境条件,利用2006年7月～12月3个季度采集的硇洲岛海域沉积物样品,进行8种孔径的套筛分选,取得不同粒径颗粒的百分比数据.运用沉积物的各种参数,结合文昌鱼的分布数据进行分析,发现硇洲岛海域文昌鱼适宜栖息底质类型为细中砂、中砂和粗中砂.中值粒径MDΦ0.547～2.745φ;四分位离差QDΦ0.536～0.980;四分位偏态SKΦ-0.147～0.101;众值粒径MoΦ0.731～3.152.φ0.2～0.85mm粒级颗粒所占比例≥58%时,文昌鱼密度显著地高.聚类分析和回归分析发现0.2～0.85mm粒级含量和文昌鱼分布密度具有明显的相关性.对比各地文昌鱼栖息底质发现,砂质结构基本一致,但具体类型存在地域差异.  相似文献   

南海海气界面潜热通量的分布特征及其对西南季风爆发影响的初步分析   总被引：4，自引：1，他引：3       下载免费PDF全文

王丽娟  王辉  闫俊岳  张增海 《海洋学报》2008,30(1):20-30

利用1982年1月至2001年12月逐日的Re_NCEP南海海表面潜热通量资料,分析了南海夏季西南季风爆发早年和晚年潜热通量在南海的时空分布特征;并通过相关对比诊断分析了潜热通量对西南季风爆发及强度的影响,初步给出了其动力学机理。结果表明,季风爆发早、晚年的前一年冬季至初春(12~3月),南海南部(5°~13°N,100°~120°E)和北部(13°~22°N,105°~120°E)的潜热通量距平符号相反,呈现反位相,季风爆发早(晚)年,前一年冬季至次年初春,南海北部的潜热通量为正(负)距平,南海南部则为负(正)距平;在季风爆发的早年和晚年,南海潜热通量表现出明显的差异,春、夏、秋季南海潜热通量正距平持续时间短(长),季风强度偏弱(强)。南海北部的潜热通量和南海北部季风强度隔季正相关。当潜热通量为正(负)距平时,同期和滞后1~3个月的海温均为负(正)异常,加大(减小)了春季南海和周围陆地陆暖海冷的海陆温差,有利于西南季风在南海北部的早(晚)爆发,西南风异常偏强(弱)。  相似文献   

北黄海二甲基硫(DMS)的海-气释放及其对气溶胶中非海盐硫酸盐的贡献   总被引：3，自引：0，他引：3  

张洪海  杨桂朋 《中国海洋大学学报(自然科学版)》2009,39(4)

根据2006年7～8月和2007年1月对北黄海进行的大面调查,分析研究了夏冬季表层海水中二甲基硫(DMS)的浓度分布和海-气交换通量.研究表明:表层海水以及大气中DMS浓度季节变化明显,夏季平均值分别是冬季的3.2和3.7倍.相关性分析显示,海水中DMS和Chl a浓度存在明显的相关性,说明浮游植物生物量是影响DMS浓度分布的1个重要因素.利用Liss和Merlivat公式(LM86)估算了北黄海夏冬季DMS的海-气交换通量,其平均值分别为7.31和4.98 μmol·m-2·d-1.另外,根据测定的大气中甲基磺酸盐(MSA)和非海盐硫酸盐(Nss-SO2-4)的浓度及比例,估算出夏冬季北黄海生源硫释放对气溶胶中Nss-SO2-4的贡献比例分别为10.1%和2.8%.此结果表明北黄海大气中Nss-SO2-4主要来源于人为排放.  相似文献   

滨海盐场养殖池塘底质硫化物的变化及其与其它因子的关系   总被引：6，自引：0，他引：6  

彭斌 《海洋湖沼通报》2008,(3)

2006年5～11月对江苏滨海盐场养殖池塘底质硫化物进行了跟踪调查,并对其与养殖环境中其它因子的关系作了研究分析.研究表明:在养殖周期内底质硫化物的变化幅度在143.26～372.45mg·kg-1,变化趋势为先升高后降低,在7、8月份含量最高.回归分析表明底质硫化物含量与有机质含量呈显著正相关.底质硫化物含量随着水体COD含量的增加而增加,两者呈极显著的正相关,底质硫化物高值出现的时期滞后于水体COD高值的产生时期.底质中硫化物随着氧化还原电位的提高而降低,两者呈极显著的负相关.  相似文献   

Nutrient concentrations and fluxes in the Changjiang Estuary during summer   总被引：5，自引：3，他引：2  

CHEN Hongtao  YU Zhigang  YAO Qingzheng  MI Tiezhu  LIU Pengxia 《海洋学报(英文版)》2010,29(2):107-119

In June 2003 and 2006 concentrations of nutrient were determined in the Changjiang Estuary. The data indicated that phosphate and nitrate did not behave conservatively in the estuary, but silicate behaved conservatively. An important mobilization of phosphate and nitrate was observed from the river up to halfway in the estuary. Both input flux (from river to estuary) and output flux (from estuary to coastal zone) of phosphate, silicate and nitrate were calculated from statistical interpretations of the salinity profiles. There was a large discrepancy between input and output fluxes of phosphate and nitrate. The river fluxes of silicate, phosphate and nitrate (f_r) are augmented 5.3%, 28.9% and 36.6% in June 2003 and 1.0%, 62.5%, 31.7% in June 2006 by internal inputs (f_i). The phosphate and nitrate fluxes are enhanced through the estuarine process, while silicate flux is unaltered. The authors present some long-term data for nutrient concentrations and the ratios of silicon to nitrogen to phosphorus in the Changjiang Estuary. Silicate level falled in the last two decades, while concentration of nitrate increased. Phosphate concentration had no significant change.  相似文献