激波管内水汽相变滞后效应的实验研究

本文研究了激波管中稀疏波、反射稀疏波对水汽-空气混合气体作用的非定常瞬态相变过程。利用两种不同波长光束的消光方法对水汽相变过程进行了测试。结果表明:水汽非定常瞬态相变发生的温度远远低于出现于自然大气中的凝结或冻结温度，混合气体膨胀越强，水汽瞬态相变的温度越低。非定常瞬态膨胀时的压力迅速下降是水汽瞬态相变温度远远低于自然大气中水汽相变温度的主要原因。水汽瞬态相变过程中，生成的微滴尺度均匀，但微滴的数密度却随时间发生变化。     

掩星接收机误差对大气温度反演精度影响仿真研究

为了评估掩星接收机误差对无线电掩星探测精度的影响,利用EGOPS软件仿真研究了多普勒偏差、多普勒频移、时钟稳定性/单差分、接收机噪声和局部多路径等对GNSS无线电掩星反演大气温度、折射率、密度、压力廓线的影响.模拟设计过程中选择METOP作为接收的LEO卫星,GPS星座作为发射系统,设置GRAS天线.从模拟的567个掩星事件中选择了一个上升掩星事件和一个下降掩星事件进行模拟分析.研究结果表明:对于设置的\"最差\"情况,温度误差最大值大部分出现在平流层顶附近,其中多普勒偏差引起的温度误差最大值接近2 K,多普勒频移引起的温度误差最大值小于0.3 K,时钟稳定性/单差分引起的温度误差最大值接近3 K,现实接收机噪声引起的温度误差最大值超过了4 K,局部多路径引起的温度误差最大值小于1.5 K.经讨论分析认为:对于高质量的无线电掩星反演,掩星接收机误差源中最主要的是接收机热噪声、时钟稳定性/单差分和多普勒偏差.文中还随机选取了30个掩星事件进行统计分析,将其温度反演结果与ECMWF分析场数据比较得出,温度误差的平均偏差在45 km高度上最大,约为1 K;最大标准偏差出现在平流层顶,约为5 K,这验证了廓线反演算法的有效性,表明了误差分析结果的正确性和普遍性.     

2000年春季北京特大沙尘暴物理化学特性的分析

2000年春季北京频频发生沙尘天气,严重影响了北京市大气环境状况.对4月6日北京地区发生的特大沙尘暴化学元素成分的分析表明北京春季沙尘污染极为严重.沙尘暴期间,20种元素总质量浓度高达1536μg/m3,是1999年同期的31.4倍.即使沙尘暴过后,污染依然严重,元素总质量浓度仍高达338.7μg/m3,是1999年春季的7倍.研究还发现,沙尘暴期间来自远方的大粒子占了很大的比例,绝大多数的元素浓度在粒径大于16μm处出现一个非常高值,远高于其他谱段的浓度;在沙尘暴后及其他时间,还没有观测到这种谱分布.沙尘暴期间的粗粒子(d>2μm)数浓度是沙尘暴后的20倍以上,细粒子(d<2μm)的数浓度是沙尘暴后的7倍.     

CINRAD/SA发射机通风散热系统的改进

建阳新一代天气雷达2001年3月正式投入运行,其后雷达故障频发,而发射机的故障尤其严重,经过反复观察,发现雷达故障与发射机的温度紧密相关:温度高则故障多.     

T639预报气温产品误差分析与订正

由于T639数值预报模式对具体区域预报有一定偏差,为了更好的利用该模式做出山东即墨本区域各自动站气温预报,制定订正方法,将订正方法运用到实际业务中,推广到相关单位,提高气温预报准确率,本文利用2013年1月至2015年12月山东省即墨市8个区域自动站的最高(低)气温实况和对应的T639数值预报24小时2m气温预报产品进行了日最高(低)气温的预报准确率、相对误差分析,并结合风向风速预报结论和地形分区,运用综合订正、季节订正、风向订正和风速订正4种误差订正方法,在对比检验的基础上,得出如下结论:在4种订正方法中,预报准确率最高为综合订正方法。     

山东黄县弧形断裂带断层泥铁元素化学种分布特征及其地震地质意义

本文利用德国Wissel公司生产的新型穆斯堡尔谱仪(Bench-MB500)对山东龙口常庄子村北黄县弧形断裂断层剖面上的多种断层泥样品进行了穆斯堡尔谱测试分析,讨论了该断层剖面上铁元素地球化学分布特征及其地震地质意义。结果显示,该断裂中央部分比较年轻的断层泥相对富集para-Fe~(2+),而两侧较老的断层泥基本由para-Fe~(3+)组成;剖面断层泥样品中铁元素的地球化学特征与断层的活动演化历史密切相关,显示了断裂带内存在复杂的水岩相互作用。     

Progress in the Study of Coastal Storm Deposits

Numerous studies have been carried out to identify storm deposits and decipher storm-induced sedimentary processes in coastal and shallow-marine areas. This study aims to provide an in-depth review on the study of coastal storm deposits from the following five aspects. 1) The formation of storm deposits is a function of hydrodynamic and sedimentary processes under the constraints of local geological and ecological factors. Many questions remain to demonstrate the genetic links between storm-related processes and a variety of resulting deposits such as overwash deposits, underwater deposits and hummocky cross-stratification (HCS). Future research into the formation of storm deposits should combine flume experiments, field observations and numerical simulations, and make full use of sediment source tracing methods. 2) Recently there has been rapid growth in the number of studies utilizing sediment provenance analysis to investigate the source of storm deposits. The development of source tracing techniques, such as mineral composition, magnetic susceptibility, microfossil and geochemical property, has allowed for better understanding of the depositional processes and environmental changes associated with coastal storms. 3) The role of extreme storms in the sedimentation of low-lying coastal wetlands with diverse ecosystem services has also drawn a great deal of attention. Many investigations have attempted to quantify widespread land loss, vertical marsh sediment accumulation and wetland elevation change induced by major hurricanes. 4) Paleostorm reconstructions based on storm sedimentary proxies have shown many advantages over the instrumental records and historic documents as they allow for the reconstruction of storm activities on millennial or longer time scales. Storm deposits having been used to establish proxies mainly include beach ridges and shelly cheniers, coral reefs, estuary-deltaic storm sequences and overwash deposits. Particularly over the past few decades, the proxies developed from overwash deposits have successfully retrieved many records of storm activities during the mid to late Holocene worldwide. 5) Distinguishing sediments deposited by storms and tsunamis is one of the most difficult issues among the many aspects of storm deposit studies. Comparative studies have investigated numerous diagnostic evidences including hydrodynamic condition, landward extent, grain property, texture and grading, thickness, microfossil assemblage and landscape conformity. Perhaps integrating physical, biological and geochemical evidences will, in the future, allow unambiguous identification of tsunami deposits and storm deposits.     

A state decoupling approach to estimate unobservable trackingsystems

If a system is unobservable, the error covariance associated with a Kalman filter will be nearly singular. As a consequence, an optimum estimation in the sense of minimum error covariance does not exist. In this paper, we show that this (unobservable) system can be transformed into a nonlinear system with a linear measurement equation. In addition to other useful features, this transformation also serves to decouple the state in such a way that an observable part can be extracted and estimated while no information can be gained and processed for the unobservable part