Improvement in Background Error Covariances Using Ensemble Forecasts for Assimilation of High-Resolution Satellite Data     

Seung-Woo LEE  Dong-Kyou LEE 《大气科学进展》2011,28(4):758-774

Satellite data obtained over synoptic data-sparse regions such as an ocean contribute toward improving the quality of the initial state of limited-area models. Background error covariances are crucial to the proper distribution of satellite-observed information in variational data assimilation. In the NMC (National Meteorological Center) method, background error covariances are underestimated over data-sparse regions such as an ocean because of small differences between different forecast times. Thus, it is necessary to reconstruct and tune the background error covariances so as to maximize the usefulness of the satellite data for the initial state of limited-area models, especially over an ocean where there is a lack of conventional data. In this study, we attempted to estimate background error covariances so as to provide adequate error statistics for data-sparse regions by using ensemble forecasts of optimal perturbations using bred vectors. The background error covariances estimated by the ensemble method reduced the overestimation of error amplitude obtained by the NMC method. By employing an appropriate horizontal length scale to exclude spurious correlations, the ensemble method produced better results than the NMC method in the assimilation of retrieved satellite data. Because the ensemble method distributes observed information over a limited local area, it would be more useful in the analysis of high-resolution satellite data. Accordingly, the performance of forecast models can be improved over the area where the satellite data are assimilated.  相似文献   

From the editors     

George C.LEE 《地震工程与工程振动(英文版)》2011,10(1):I0001-I0001

Dear Contributors,Readers and Friends: 2011 milestones the tenth anniversary of the Journal of Earthquake Engineering and Engineering Vibration.we first want to take this opportunity to express our gratitude to those retiring members of the Editorial Board for their valuable contributions in the past,and to welcome those who joined the Editorial Board this year. As we mentioned in our message to you in December 2010,effective 20ll,the journal is officially co-sponsored by the Huixian Earthquake  相似文献   

Geochemistry of ultramafic xenoliths in Cenozoic alkali basalts from Jiangsu province, eastern China and their geological implication     

SHAO-WEI HUANG  YUNG-TAN LEE  JU-CHIN CHEN  KUNG-SUAN HO  MENG-LUNG LIN  YEN-TSUI HU  REN-YI HUANG 《Journal of Earth System Science》2013,122(3):777-793

  相似文献   

大兴安岭中生代两类流纹岩与玄武岩的成因联系   总被引：2，自引：0，他引：2  

林强  葛文春  孙德有  吴福元  元钟宽  李文远  尹成孝  陈明植  闵庚德  权致纯 《吉林大学学报(地球科学版)》2000,30(4):322-328

根据地质产状和地球化学特征大兴安岭中生代流纹岩类可划分为高Ti流纹岩和低Ti流纹岩。高Ti流纹岩类与亚碱性系列玄武岩类紧密伴生 ,两者在地球化学上构成连续变异系列。低Ti流纹岩类则与碱性系列玄武岩类构成地球化学双峰态。岩相学和地球化学研究表明 ,这两类流纹岩与该区同期玄武岩类有着密切的成因联系 :起源于地幔柱亏损成分的亚碱性系列玄武岩浆经过单斜辉石、斜长石、磷灰石、锆石的分离结晶 ,形成亚碱性系列低钾玄武岩→高钾玄武岩→高Ti流纹岩演化系列 ;起源于地幔柱富集成分的碱性系列玄武岩浆侵入下地壳 ,使下地壳岩石发生部分熔融 ,形成碱性系列玄武岩 -低Ti流纹岩双峰态组合  相似文献   

沙尘分析及等离子空气清洁系统沙尘去除效果的评价     

LEE Jae-keun  KIM Seong-chan  NOH Hyung-soo  董旭辉  狄一安 《中国沙漠》2003,23(3):316-321

本研究对在中国和韩国采集的沙尘的粒径分布及质量浓度进行了测定,使用黄沙标准物质对基于静电沉降原理的等离子空气清洁系统的去除沙尘效率进行了评价。本研究所使用的黄沙采集于北京和汉城,其粒径中值在7.0~80μm之间,浓度范围为300~1462μg·m^-3。在单通道测试中,沙尘去除效果随粒径增大和流速降低而增加。系统速度为1.0m·s^-1时,去除率大于80%。在27m2的房间中,进行多通道测试时,浓度为300μg·m^-3的大气颗粒物仅用10min即可降至150μg·m^-3。因此,等离子空气清洁系统能够有效地去除沙尘及保持室内空气质量。  相似文献   

A comparison of scavenging and deposition processes in global models: results from the WCRP Cambridge Workshop of 1995   总被引：2，自引：1，他引：1  

P. J. RASCH  J. FEICHTER  K LAW  N. MAHOWALD  J. PENNER  C. BENKOVITZ  C. GENTHON  C. GIANNAKOPOULOS  P. KASIBHATLA  D. KOCH  H. LEVY  T. MAKI  M. PRATHER  D. L. ROBERTS  G.&#;J. ROELOFS  D. STEVENSON  Z. STOCKWELL  S. TAGUCHI  M. KRITZ  M. CHIPPERFIELD  D. BALDOCCHI  P. McMURRY  L. BARRIE  Y. BALKANSKI  R. CHATFIELD  E. KJELLSTROM  M. LAWRENCE  H. N. LEE  J. LELIEVELD  K. J. NOONE  J. SEINFELD  G. STENCHIKOV  S. SCHWARTZ  C. WALCEK  D. WILLIAMSON 《Tellus. Series B, Chemical and physical meteorology》2000,52(4):1025-1056

We report on results from a World Climate Research Program workshop on representations of scavenging and deposition processes in global transport models of the atmosphere. 15 models were evaluated by comparing simulations of radon, lead, sulfur dioxide, and sulfate against each other, and against observations of these constituents. This paper provides a survey on the simulation differences between models. It identifies circumstances where models are consistent with observations or with each other, and where they differ from observations or with each other. The comparison shows that most models are able to simulate seasonal species concentrations near the surface over continental sites to within a factor of 2 over many regions of the globe. Models tend to agree more closely over source (continental) regions than for remote (polar and oceanic) regions. Model simulations differ most strongly in the upper troposphere for species undergoing wet scavenging processes. There are not a sufficient number of observations to characterize the climatology (long‐term average) of species undergoing wet scavenging in the upper troposphere. This highlights the need for either a different strategy for model evaluation (e.g., comparisons on an event by event basis) or many more observations of a few carefully chosen constituents.  相似文献   

日本凋毛藻碳酸酐酶基因及其编码的蛋白特征     

刘晨临  黄晓航  LEE Yookyung  LEE Hungkum  李光友 《海洋学报》2006,28(3):161-166

碳酸酐酶CA(EC 4.2.1.1)是含锌原子的金属蛋白酶,该酶的基本功能是催化CO₂与HCO₃-间的相互转换[1].该反应在许多生物过程中都发挥着重要的作用,例如离子交换、呼吸作用、pH稳定性、捕获CO₂和光合作用等[2~5].CA广泛分布于各种生物中,已知的CA酶根据氨基酸序列被分为-αCA,-βCA和γ-CA三种类型[5~7].这3种类型的CA酶序列间的相似性很低,被认为是由不同的途径进化而来的[7].α-型的CA酶在动物、植物、绿藻、细菌和蓝细菌中都有发现[7],在藻类中报道的α-型CA还很少.迄今为止只在衣藻中发现2种异构体,在盐藻中发现3种[8,9],在红藻中还未见报道.  相似文献   

海洋环境立体监测系统的设计方法   总被引：10，自引：1，他引：9  

罗续业  周智海  曹东  李彦 《海洋通报》2006,25(4):69-77

“九五”和“十五”期间,在国家海洋863计划的支持下,我国分别在上海和台湾海峡及毗邻海域建立了两个区域性海洋环境立体监测示范系统。在这两个示范系统的技术研究成果的基础上,通过分析国际海洋立体监测系统的设计模型,提出了区域性海洋环境立体监测系统的设计原则和设计方法,包括:系统结构、数据与信息服务通信网络、数据处理中心、数据流程以及系统功能等方面的设计方法。  相似文献   

Multivariate analysis of fluorescence and source identification of dissolved organic matter in Jiaozhou Bay, China   总被引：1，自引：0，他引：1  

JIANG Fenghu  YANG Baijuan  LEE Frank Sen-Chun  WANG Xiaoru  CAO Xuan 《海洋学报(英文版)》2009,28(2):60-72

Hierarchical clustering analysis and principal component analysis (PCA) methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy (EEMs) data sets of samples collected from Jiaozhou Bay, China. The results demonstrate that multivariate analysis facilitates the complex data treatment and spectral sorting processes, and also enhances the probability to reveal otherwise hidden information concerning the chemical characteristics of the dissolved organic matter (DOM). The distribution of different water samples as revealed by multivariate results has been used to track the movement of DOM material in the study area, and the interpretation is supported by the results obtained from the numerical simulation model of substance tracing technique, which show that the substance discharged by Haibo River can be distributed in Jiaozhou Bay.  相似文献   

Sensitivity evaluation of the flash flood warning system introduced to ungauged small mountainous basins in Korea     

YOO Chulsang  LEE Jinwook  CHANG Kwonhee  YANG Dongmin 《山地科学学报》2019,(5)

This study evaluates the uncertainty involved in the determination of the flash flood guidance(FFG) of the flash flood warning system(FFWS) for a small mountainous region(FFWS_MR)in Korea. The sensitivity is evaluated both at each step to determine the FFG and for all steps together. The results show that the relative difference of the FFG is about 50% of the current system, most of which involves the channel width. Especially, the use of some specific empirical equations to estimate the major parameters results in a considerable amount of the relative difference of the FFG. In addition, though only four basins were field-surveyed, it is found that the indirect estimation of the major parameters always introduces some amount of additional uncertainty. In conclusion, accurate estimation of the major parameters must be the most important procedure to derive an accurate FFG, among which the channel cross-section at the exit of the basin lies at the center.  相似文献