测风声雷达数据自动采集与处理系统

一、测风声雷达简介 声雷达是低层大气遥感探测的重要工具之一。由于大气对声波折射指数的变化比对电磁波大6个量级,因此,声雷达用于探测大气参数有较高的灵敏度。 声雷达应用于大气边界层中温度梯度与风速、风向的测量。这些参数的测量对大气湍流、大气污     

声回波团块结构的温湿脉动特征

本文分析了北京地区暖湿时期的声回波团块结构与温湿脉动量的关系,得到下面三点初步结果:1.温湿脉动联合作用结果的声折射率脉动方差(n~2)随时间的起伏变化与声回波强度随时间变化的团块结构形态非常相似.2.从声回波团块结构的传真图片类型特征来看是属于潮湿型的,其湿空气稳定度层结(考虑水汽通量作用)是接近中性层结.3.在有团块回波时期的声折射率脉动(n)谱值比无团块回波时期的n谱值要大10倍.     

用声遥感方法计算对流边界层中洋面上的湍流热通量

在中美海气相互作用第二航次考察中,在赤道西太平洋的三个断面上进行了单点声雷达观测,定量测量了温度脉动结构系数C_T2,本文在Wyngaard提出的相似理论基础上,进一步讨论了洋面上不稳定大气层结时,用C_T2计算海面热通量的方法,由于洋面上空气湿度大,公式中必需考虑水汽脉动结构系数C_e2和水汽脉动与温度脉动相关的结构系数C_eT对热通量计算的影响,给出了计算热通量的参数化表达式,用声雷达测量的热通量与整体输送系数方法计算的热通量做了比较,结果较一致。     

沿海海—气界面的化学物质交换

沿海海－气界面化学物质的交换对生物地球化学循环起着十分重要的作用。大气沉降过程是化学物质进入沿海区域的重要途径之一。物质平衡估算的结果指出，在某些沿海区域，经由大气输入的若干痕量物质的总量几乎相当于河流的输入量，有的甚至更多。大气沉降作用是一些沿海区域氮化物的重要来源，并与富营养化有紧密关系。     

太平洋中低纬海水中的二氧化碳分布特征及其与海洋环境条件的关系

根据1986年11月至1990年6月进行的中美热带西太平洋海-气相互作用(TOGA)联合考查和1995年10月至1996年6月“中日副热带联合调查”期间获得的14个航次大气和海水CO₂的观测资料,给出了主要观测海区CO₂的源与汇的分布特征:在赤道地区5°N~5°S,130°~165°E观测到的表面水中二氧化碳分压的值超过了大气中二氧化碳分压1.5~4.5 Pa,结果表明该海区对大气CO₂而言是源,但是该值远小于在中赤道测到的+9.1 Pa和在东赤道太平洋所测的+15 Pa的值.由此表明热带太平洋CO₂源的强度是向西减弱的.副热带海区在秋季对大气CO₂而言是较强的源,春季是汇.对影响海水CO₂变化的主要因素温度、盐度等进行了讨论,表明CO₂的分布变化直接受海流、水团、黑潮和ENSO事件影响.     

北极夏季冰面上近地层特征及热量收支问题

应用1999年8月19～24日我国第1次北极考察资料对北极夏季近地层气象要素梯度特征和冰面热量收支问题进行了讨论.北极夏季近地层相对于冰面的相对湿度很大,经常接近于饱和状态,冰温具有明显的日变化,夜间冰面附近冰温梯度较大,白天很小.在冰温垂直分布中20cm冰层温度有时可出现极大值.冰面热量收支计算表明,夜间冰面辐射冷却损失热量主要由冰层向冰面热量输送来补偿.白天冰层的热量主要来源于穿透短波辐射,冰面和以下冰层间的热量交换很低.白天冰面冰雪融化热量是不可忽视的.     

Natural and anthropogenic nitrogen uptake by bloom-forming macroalgae

The frequency and duration of macroalgal blooms have increased in many coastal waters over the past several decades. We used field surveys and laboratory culturing experiments to examine the nitrogen content and delta(15)N values of Ulva and Gracilaria, two bloom-forming algal genera in Narragansett Bay, RI (USA). The northern end of this bay is densely populated with large sewage treatment plant nitrogen inputs; the southern end is more lightly populated and opens to the Atlantic Ocean. Field-collected Ulva varied in delta(15)N among sites, but with two exceptions had delta(15)N above 10 per thousand, reflecting a significant component of heavy anthropogenic N. This variation was not correlated with a north-south gradient. Both Ulva and Gracilaria cultured in water from across Narragansett Bay also had high signals (delta(15)N= approximately 14-17 per thousand and 8-12 per thousand, respectively). These results indicate that inputs of anthropogenic N can have far-reaching impacts throughout estuaries.     

Characterization and composition of heavy metals and persistent organic pollutants in water and estuarine sediments from Gao-ping River, Taiwan

The objective of this study was to determine the concentrations and possible sources of heavy metals and persistent organic pollutants (POPs) in water and estuarine sediments from Gao-ping River in order to evaluate the environmental quality of aquatic system in southern Taiwan. High concentrations of heavy metals including Cr, Zn, Ni, Cu and As, ranging from 10.7 to 180 mg/kg-dry weight (dw), were detected in sediments from Gao-ping River. When normalized to the principal component analysis (PCA), swinery and electroplating wastewaters were found to be the most important pollution sources for heavy metals. Of various organochlorine pesticide (OCP) residues detected, aldrin and total-hexachlorocyclohexane (HCH) were frequently found in sediments. The total concentrations of OCPs were in the range 0.47-47.4 ng/g-dw. Also, the total-HCH, total-cyclodiene, and total-dichlorodiphenyltrichloroethane (DDT) were in the range 0.37-36.3, 0.21-19.0, and 0.44-1.88 ng/g-dw, respectively. The polychlorinated biphenyl (PCB) concentrations in sediments from Gao-ping River ranged between 0.37 and 5.89 ng/g-dw. The PCB concentrations are positively correlated to the organic contents of the sediment particles. alpha-HCH was found to be the dominant compound of HCH in the sediments, showing that long-range transport may be the possible source for the contamination of HCH in sediments from Gao-ping River. In summary, trace amounts of POPs in estuarine sediments from Gao-ping River were detected, showing that there still exist a wide variety of POP residues in the river sediments in Taiwan. These POP residues may be mainly from long-range transport and weathered agricultural soils, while heavy metal contamination is primarily from the swinery and industrial wastewaters.