副高、极涡因子对我国夏季降水的影响

利用奇异值分解方法(SVD)分别分析了北半球副高指数和北半球极涡指数对我国夏季降水(6～8月)的影响,并详细讨论了对我国夏季降水影响重大的具体关系,以及它们影响的区域情况.研究发现,我国夏季降水主要受前期冬季极涡强弱的影响.冬季副高因子的影响是半球范围的,而春季副高因子的影响主要取决于我国南部的副高系统.综合研究极涡、副高两者对我国夏季降水的影响要比分别研究它们各自的影响所得模态的代表性好,预报价值也更高.     

Release of mercury from intertidal sediment to atmosphere in summer and winter

The release of mercury from intertidal sediment to atmosphere was studied based on the simulated experiment. The experiment samples were collected from the Haibo Estuary (S1) and the Licun Estuary (S2) of the Jiaozhou Bay in China,which are seriously polluted with mercury. The results show that the mercury in sediment releases rapidly to atmosphere under solar radiation. After 8 hours of solar radiation,mercury concentrations decrease from 5.62 μg/g and 2.92 μg/g to 2.34 μg/g and 1.39 μg/g in S1 and S2 sediments respectively in summer,and decrease from 5.62 μg/g and 2.92 μg/g to 4.58 μg/g and 2.13 μg/g respectively in winter. The mercury species in the sediment change markedly under solar radiation. The concentrations of mercury bound to organic matter decrease significantly from 2.73 μg/g to 0.31 μg/g in S1 and from 2.07 μg/g to 0.31 μg/g in S2,and the released mercury mainly comes from mercury bound to organic matter. Mercury flux shows distinguishing characteristic of diurnal change,and it increases rapidly in the morning with the rising of solar radiation intensity,but decreases in the afternoon. The mercury flux increases with sediment temperature and solar radiation intensity. The rapid release of mercury in intertidal sediment plays an important role in the regional mercury cycle.     

2013年夏季北黄海浮游植物群集

利用Utermöhl方法,对2013年夏季取得的北黄海浮游植物样品进行鉴定分析,共鉴定出浮游植物3门60属114种(不包括未定名种),其中,硅藻42属75种,甲藻16属37种,金藻2属2种。群落组成以硅藻为主,其次是甲藻,然后是金藻。调查海区浮游植物的生态类型以温带近岸性为主,主要优势种为:小等刺硅鞭藻 Dictyocha fibula、裸甲藻 Gymnodinium sp.、螺旋环沟藻 Gyrodinium spirale、蜂腰双壁藻 Diploneis bombus 和具槽帕拉藻 Paralia sulcata。浮游植物细胞丰度介于0.037 0 × 10³ ～ 32.3 × 10³ cells·L^-1,平均值为2.04 × 10³ cells·L^-1;浮游植物细胞丰度大致从近岸到外海呈逐步降低趋势,在北黄海西部近岸的表层水体达到最高值32.3 × 10³ cells·L^-1,调查区东南部靠近外海区域也出现了丰度高值区;浮游植物垂直分布总体特征是随水深的增加而减少,由近岸向外海逐步降低。香农-威纳多样性指数在调查区西南部较高,而Pielou均匀度指数则在东部呈现高值区域。典范对应分析(CCA)显示,影响浮游植物优势种丰度分布的主要因素是营养盐,而跟盐度和温度的相关性不明显。     

The response of annual runoff to the height change of the summertime 0°C level over Xinjiang

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960–2002, the variance of the summertime 0°C level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0°C level height in Xinjiang correlates well with that of the annual river runoff, especially since the early 1990s, but it differs from region to region, with both the average height of the 0°C level and runoff quantity significantly increasing over time in the Altay-Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0°C level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0°C level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

干旱少雨的夏季：1999年夏季（6—8月）山东天气评述

１　天气概述１９９９年夏季（６－８月）我省的天气气候特点是：气候条件异常,气温比常年偏高;７月４日进入主汛期,平均降水量明显偏少,且时空分布极不均匀。全省季平均气温为２５５℃,比常年偏高０３℃。全省平均降水量为２６８２ｍｍ,较常年偏少３５％（１４７０ｍｍ）,降水时空分布极不均匀,降水主要集中在６月上旬和８月上旬,各地雨量普遍偏少,只有局部地区降水量明显偏多,旱情十分严重。季降水量分布（图１）：图１　１９９９年夏季（６－８月）全省雨量分布鲁南、半岛南部、鲁北大部以及鲁中山区北部各县市降水量…     

夏季异常高温干旱过程的个例分析

阐述天体引潮力原理,并从天体引潮力角度讨论营口１９９７年夏季异常高温及１９９８年６月下旬至７月上旬的高温干旱过程。     

东亚夏季气候主要模态的年际变化及其机理

主要研究了东亚(中国和日本)夏季气候(降水和气温)主要模态的年际变化及其机理。研究发现,中国区域夏季降水和气温的大尺度年际变化间有很强的耦合:大范围多(少)雨对应大范围低(高)温。奇异值分解的第一个模态的长期变化主要反映了长江中下游地区降水逐年增加(变湿)的趋势而气温逐年降低(变冷)的趋势。在70年代中期以后,长江中下游地区降水和气温耦合变化的准两年分量明显增强。研究表明,影响长江中下游地区夏季降水和气温年际变化的大尺度环流背景异常十分相似,即主要是两个遥相关型:太平洋-日本(PJ)型和欧亚型遥相关型。与夏季东亚梅雨异常相联系的长江中下游地区降水和气温异常是中高纬度干冷空气和低纬度暖湿空气相互作用的结果。热带西太平洋海表温度异常和相关的对流活动的年际变化通过PJ型对东亚地区夏季降水和气温的年际变化产生十分显着的影响。西太平洋对流活动与北半球大气环流遥相关的相互作用有明显的季节性。PJ型不仅是夏季西太平洋对流活动与北半球夏季热带外地区500hPa高度场年际变化耦合相互作用的最重要模态,而且也是两者各自变化的一个十分重要的模态。1984年夏季北半球500hPa位势高度主振荡型分析表明存在着能量从热带西太平洋向东亚北部的PJ型的振荡传播。低纬度的影响可传播到70°N,同时也存在能量从高纬度向低纬度的传播.即从极地传播到70°N。高纬度和低纬度的影响在70°N附近汇合。     

青藏高原冬春积雪对长江流域夏季降水的影响

本文根据青藏高原主体72个气象站日测资料建立的积雪序列分析了高原积雪对长江流域夏季降水的影响,高原冬春积雪异常与长江流域汛期特别是6、7月降水呈显著的正相关关系.青藏高原冬春多雪年,随后夏季多出现Ⅱ、Ⅲ类雨型,长江中游和下游鄱阳湖地区多偏涝;青藏高原冬春少雪年,随后夏季多出现Ⅰ、Ⅱ类雨型,长江下游鄱阳湖地区多偏旱,长江中游多正常偏旱.多(少)雪年东亚洲大陆上空的气温明显偏低(高),而大陆南部海洋上空的气温明显偏高(低),降低(增加)了陆海温差,延迟(促进)了东亚夏季风的到来,一定程度上减弱(加强)东亚季风的强度.多(少)雪随后夏季,由于南亚夏季风和东亚夏季风都明显减弱(增强),对流层中低层从孟加拉湾吹向中南半岛的西南风减弱(增强),我国大陆东部的南风也明显减弱(增强),西太副高偏南(北);青藏高原东南侧到中南半岛北部的上升运动较弱(强),长江中下游及其以东洋面上升运动较强(弱),长江中下游地区多(少)雨.     

鄱阳湖水体夏季气温效应

本文讨论了定量计算湖泊纯水体气温效应的方法,在计算鄱阳湖水体夏季纯水体气温效应值的基础上,重点分析鄱阳湖水体夏季气温效应的特征、强度和分布,其结果是鄱阳湖水体夏季对湖区气温影响呈热源效应。表现在提高了湖区夏季平均气温,湖中心棠荫站比湖外高O.1—1.0℃,纯水体气温效应为0.4℃。随着距水体距离的增大,气温效应也逐渐减弱,水体影响气温的范围约为10—40km。由于湖区夏季受到副热带高压控制,陆风比湖风旺盛,气温效应夜间比白天强,加上地形的作用,影响范围南部比北部大。1980—1987年间的7、8月考察资料也和上述结果相吻合。