Dating of two thermokarst lakes in Beiluhe Basin,Qinghai-Tibetan Plateau

Most of the thermokarst lakes are spread appreciably in Beiluhe Basin,Qinghai-Tibet Plateau,China,where ice-rich permafrost exists.Two typical thermokarst lakes with differing area and depth were examined to ascertain their age.We obtained lake-bottom samples of 50 cm length from lake BLH-A and 25 cm length from lake BLH-B.Environmental 137 Cs and 210 Pb and radiocarbon age dating techniques were applied to the 50 cm and 25 cm samples,respectively.The results indicate that the initiation of BLH-A is about 800-900 a B.P.,and approximately 1,450±30 a B.P.to 2,230±30 a B.P.for BLH-B.These results will provide scientific bases for sedimentological study and thermokarst activity in Beiluhe Basin.     

绵阳市度日数特征及其变化趋势分析

从20世纪50年代以来,度日数一直作为气候变化与供暖关系的一个综合评价指标。基于全球变暖可能对我国供暖天数和温度产生深刻的影响,本文采用绵阳市1946~2005年共49年的日最低、最高气温资料,分析了绵阳市度日数年变化特征,并对其进行了趋势分析。结果表明:绵阳市历年供暖度日数最小值处于1998年,比1976年最大值低93.5%,10a年均供暖度日数变化趋势为二次曲线;制冷度日数波动性很大,1960~1979年在1500℃·d左右波动,1979~1990年在1400℃·d左右波动,1990年以后基本处于1500℃·d以上,10a年均制冷度日数拟合趋势曲线为三次曲线。基于Mann-Kendall(M-K)检验法,在α=0.05水平下,对绵阳市供暖和制冷度日数进行检验,研究发现:供暖度日数明显减少,1992年为突变起始年份;制冷度日数波动增长,且自1997年起突变。     

湖南两次流域性致洪暴雨异同点分析

利用常规气象资料、水情资料及灾情资料,对发生地点、季节及影响系统相似的2010年7月8-14日和2012年7月11-19日两次湖南省持续性大范围暴雨天气过程进行对比分析,结果表明：（1）两次暴雨过程均具有持续时间长、暴雨频繁且集中、累计雨量大、洪涝严重等特点;（2）东北冷涡加强、副高东退南落,冷、暖空气在湖南交汇,导致连续性暴雨发生;（3）“10.7”暴雨过程冷、暖气流势力相当,雨带呈东西向,稳定少动,致灾性强.而“12.7”暴雨过程冷空气势力较强,雨带呈移动性,虽然致灾范围广,但灾情较前者轻.     

Stationary Wave Activity Associated with the East Asian Winter Monsoon Pathway

The pathway of the East Asian winter monsoon(EAWM) that usually leads to the out-of-phase pattern of surface air temperature between northern and southern East Asia is an important feature in the variability of the EAWM besides its strength.Using the European Centre for Medium-Range Weather Forecasts 40-year(ERA40) reanalysis dataset,this study investigates the pathway-related stationary wave activity to explore the mechanism of the interannual variations in the EAWM pathway.It reveals that when the southern pathway of the EAWM is strong,the phase of the climatological stationary wave tends to be shifted westward significantly in both the horizontal and vertical directions by an anomalous wavenumber 2 pattern at mid-latitudes,whereas the changes are relatively small in the subtropics.The horizontal changes in the stationary wave phase facilitate a north-south-oriented East Asian trough in the middle troposphere that eventually produces the strong southern pathway of the EAWM.The vertical changes in the stationary wave,in contrast,feature a westward-tilted phase line with height over the North Pacific,indicating enhanced upward propagation of waves into the stratosphere.This result suggests that the phase of stationary waves at mid-latitudes dominate the interannual variations in the EAWM pathway.Moreover,it supports our previous interpretation of the possible role of the North Pacific sea surface temperature(SST) in the EAWM pathway variability.It also implies that the excitation of anomalous mid-latitude stationary waves may be the key in the response of the EAWM pathway to the North Pacific SST.     

Stationary Wave Activity Associated with the East Asian Winter Monsoon Pathway简

The pathway of the East Asian winter monsoon（EAWM） that usually leads to the out-of-phase pattern of surface air temperature between northern and southern East Asia is an important feature in the variability of the EAWM besides its strength.Using the European Centre for Medium-Range Weather Forecasts 40-year（ERA40） reanalysis dataset,this study investigates the pathway-related stationary wave activity to explore the mechanism of the interannual variations in the EAWM pathway.It reveals that when the southern pathway of the EAWM is strong,the phase of the climatological stationary wave tends to be shifted westward significantly in both the horizontal and vertical directions by an anomalous wavenumber 2 pattern at mid-latitudes,whereas the changes are relatively small in the subtropics.The horizontal changes in the stationary wave phase facilitate a north-south-oriented East Asian trough in the middle troposphere that eventually produces the strong southern pathway of the EAWM.The vertical changes in the stationary wave,in contrast,feature a westward-tilted phase line with height over the North Pacific,indicating enhanced upward propagation of waves into the stratosphere.This result suggests that the phase of stationary waves at mid-latitudes dominate the interannual variations in the EAWM pathway.Moreover,it supports our previous interpretation of the possible role of the North Pacific sea surface temperature（SST） in the EAWM pathway variability.It also implies that the excitation of anomalous mid-latitude stationary waves may be the key in the response of the EAWM pathway to the North Pacific SST.     

800年来苏北废黄河三角洲的演变模式

根据历史资料、数据和相关研究,结合研究区域背景,分析苏北废黄河三角洲的演变。结果显示,岸线演变在发育阶段和侵蚀阶段分别为向海延伸约90 km和侵蚀后退约22 km,面积相差约800 km2,三角洲地貌演变表现为岸线平直-曲折-平滑-平直的过程。在废三角洲陆海相互作用的基础上,运用演化模式分析三角洲的演变过程。该三角洲演变可以分为7个演变阶段,发育期在径流和潮流作用下以沙洲并陆淤积延伸方式进行,侵蚀期在波浪和潮流作用下以沙洲合并侵蚀后退和淤积外长交替侵蚀的方式。泥沙输运、人类活动和气候变化对废三角洲的演变有重要影响,巨量的来沙是三角洲发育的原因,泥沙平衡被打破是侵蚀的主要原因。发育期中,泥沙输运影响淤积速度和位置,人类活动和气候变化影响黄河河道迁移、输沙量和产沙量;侵蚀期中,泥沙输运影响侵蚀状态,人类活动在一定程度上影响海岸带冲/淤,气候变化将影响三角洲的演变趋势。     

北部湾北部生态系统结构与功能研究Ⅱ.浮游动物数量分布及优势种

为了解北部湾北部海区浮游动物数量分布规律及优势种组成,2006—2007年对北部湾进行4个航次的综合性调查。根据浮游动物样品分析结果,研究了北部湾北部浮游动物的丰度、生物量和优势种组成,并利用Spearman等级相关法分析丰度与环境因子间的关系。研究结果表明,北部湾北部浮游动物丰度年均值(183.5±142.9)ind/m3,丰度的季节分布由高到低依次为秋季、夏季、冬季、春季;生物量年均值(139.5±116.8)mg/m3,由高到低依次为春季、秋季、冬季、夏季特征。平面分布上,春、秋两季丰度分布呈远岸高近岸低的趋势,而夏、冬两季则在近岸海域形成高丰度区。生物量的平面分布趋势与丰度的分布趋势基本一致。丰度变化与环境因子的相关性显著,水深、温度及叶绿素a浓度是影响丰度分布的主要因素。肥胖软箭虫Flaccisagitta enflata、亚强次真哲水蚤Subeucalanus subcrassus和间型莹虾Lucifer intermedius在北部湾北部的优势地位显著,优势种演替具有明显的季节性。     

印度尼西亚海域潮波的数值研究

基于ROMS模式构建了模拟区域为(15.52°S-7.13°N,110.39°~134.15°E)水平分辨率为2′的潮波数值模式,分别模拟了印尼海域M2、S2、K1、O1四个主要分潮。模拟结果与29个卫星高度计交叠点上的调和常数进行比较,符合较好。M2分潮的振幅均方根差为3.4cm,迟角均方根差为5.9°;S2分潮的振幅均方根差为1.7cm,迟角均方根差为6.3°;K1分潮振幅均方根差为1.1cm,迟角均方根差为5.8°;O1分潮振幅均方根差为1.2cm,迟角均方根差为4.4°。M2、S2、K1、O1分潮向量均方根差分别为3.8cm、2.4cm、1.9cm和1.3cm,模拟结果的相对偏差在10%左右。根据计算结果分析了印尼海域的潮汐特征及潮能传播规律,结果显示:爪哇海以外的印尼海域主要为不规则半日潮区;全日潮潮能主要由太平洋传入印尼海域,而半日潮潮能则是从印度洋传入印尼海域。     

东海表层水体中的多环芳烃及其沉积通量估算

以东海陆架水体中溶解态多环芳烃(PAHs)含量为基础,引入颗粒相-水相间的物质吸附系数(Koc)计算悬浮颗粒物中PAHs有机碳归一化含量,结合陆架沉积物有机碳的年埋藏通量,估算东海陆架沉积物中PAHs沉积通量。结果显示:水体中溶解态的15种PAHs总含量为(701±392)ng/L,变化范围为412~1 032ng/L,PAHs组成以3环为主。计算得到的悬浮颗粒物中15种PAHs有机碳归一化含量为20~28μg/g,对应的PAHs沉积通量为150~210t/a。估算结果与实测沉积物中PAHs含量和沉积通量结果基本吻合,表明实验室模拟实验获取的化合物Koc值适用于东海颗粒相-水相间的分配模型,证实悬浮颗粒物有机碳含量在控制PAHs两相分布过程中起着重要作用。同时,该方法为海洋沉积物中PAHs沉积通量的估算提供一种新途径。