侧视雷达影像距离-共面模型严密定位   总被引：1，自引：1，他引：0  

程春泉  张继贤 《遥感学报》2012,16(5):881-894

本文对现有侧视雷达遥感影像的几何构像模型在摄影测量应用中的不足进行了理论分析,以外方位元素作为定向参数,依次建立了像点坐标显函数形式的距离-共面(R-Cp)方程、地心直角坐标系中星载侧视雷达影像的距离-共面方程、以及星载侧视雷达遥感影像的严密定位模型,并进行了稀少控制点条件的星载TerraSAR-X影像定位试验。理论和试验表明,本文所建立的R-Cp严密定位模型,使得雷达影像像点量测坐标作为摄影测量观测值的属性得到体现,容易吸收和利用光学遥感影像基于共线方程模型发展起来的成熟的数字摄影测量数据处理方法,有利于提高雷达遥感影像摄影测量数据处理的严密性、稳定性、可靠性及数据处理效率。  相似文献   

The Dynamical and Climate Tests of an Atmospheric General Circulation Model Using the Second-Order Adams-Bashforth Method          下载免费PDF全文

赵滨  钟青 《Acta Meteorologica Sinica》2009,23(6):738-749

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The Impact of Mid- and High-Latitude Rossby Wave Activities on the Medium-Range Evolution of the EAP Pattern During the Pre-Rainy Period of South China          下载免费PDF全文

SHI Ning  BUEH Cholaw  JI Liren  WANG Panxing 《Acta Meteorologica Sinica》2009,23(3):300-314

Based on the NCEP DOE AMIP II daily reanalysis data (1979{2005), the evolution of the East Asia/Pacific(EAP) teleconnection pattern during the pre-rainy period of South China is studied on the medium-range time scale. It is found that positive and negative EAP patterns share a similar generation process. In the middle and upper troposphere, Rossby wave packets emanating from the northeast Atlantic or Europe propagate toward East Asia along the Eurasian continent waveguide and finally give rise to the three anomaly centers of the EAP pattern over East Asia. Among the three anomaly centers, the western Pacific subtropical center appears the latest. Rossby wave packets propagate from the high latitude anomaly center toward the mid-latitude and the subtropical ones. The enhancement and maintenance of the subtropical anomaly center is closely associated with the subtropical jet waveguide and the incoming Rossby wave packets from the upstream. In the lower troposphere, Rossby wave packets emanate from the subtropical Asia toward East Asia. Positive and negative EAP patterns could not be regarded as "mirrors" to each other with simply re- versed phase. For the positive pattern, the positive height anomaly center around the Scandinavia Peninsula keeps its strength and position during the mature period, and the Rossby wave packets thus propagate persistently toward East Asia, facilitating a longer mature time of the positive pattern. As for the formation of the negative EAP pattern, however, the incoming Rossby wave energy from the upstream contributes to both the enhancement and southeastward movement of the negative anomaly belt from the Yenisei River to the Bering Strait and the positive anomaly center around Mongolia. At the peak time, the two anomlous circulations are evolved into the Northeast Asia and the mid-latitude anomaly centers of the negative pattern, respectively. The energy dispersion of Rossby wave packets is relatively fast due to the predominant zonal circulation in the extratropics, causing a shorter mature period of the negative pattern. During the pre-rainy period of South China, the prevalence of the EAP pattern signiˉcantly affects the rainfall over the region south of the Yangtze River. The positive (negative) EAP pattern tends to causepositive (negative) precipitation anomalies in that region. This is di?erent from the earlier research findingsbased on monthly mean data.  相似文献   

基于SWAT模型的汉江流域径流模拟   总被引：1，自引：0，他引：1  

夏智宏  周月华  许红梅 《气象》2009,35(9):59-67

应用SWAT(Soil and Water Assessment Tool)分布式水文模型对汉江流域1971-2000年30年逐月径流进行了模拟.结果表明:模型模拟精度高于评价标准(模拟效率Ens>0.5,相关系数r 2>0.6),SWAT模型适用于汉江流域的径流模拟;水量平衡各要素中,30年月、年平均蒸散发量、地表径流量、土壤对地下水补给量、土壤含水变化量、地下水侧流量分别占降水量的55.97%、25.88%、17.64%、0.26%、0.25%,蒸散发是该流域水量的主要输出项;各月30年平均降水量变化趋势与地表径流量变化趋势较一致,而与基流量变化趋势一致性较差;30年流域降水量年变化趋势与地表径流量、基流量的变化趋势较一致;30年月、年地表径流量对降水的响应程度高于基流.  相似文献   

PCVSAT单收站常见故障分析及处理   总被引：2，自引：2，他引：0  

黄毅  王小娟  黄鑫 《气象科技》2009,37(1):125-126

多年来,PCVSAT单收站为天气预报、气候研究、气象信息服务等工作作出了重要贡献.  相似文献   

沈阳市新城子铬渣堆存区土壤铬污染分布及形态研究          下载免费PDF全文

惠秀娟  孟雪莲  徐成斌  马溪平  付保荣 《气象与环境学报》2009,25(6):64-67

采用 Tessier A连续提取法研究分析了沈阳市新城子铬渣堆存区土壤中重金属铬的污染分布和迁移转化规律。结果表明：土壤中重金属铬的5 种形态分布, 主要以残渣态和碳酸盐结合态为主,分别占总量的49.74%和21.40%,而有机结合态含量最低,占总铬含量的6.25%。不同的功能区域铬的形态分布有所不同。总体的分布特征是残渣态大于碳酸盐结合态大于交换态大于铁锰氧化态大于有机态。  相似文献   

Relationship Between the Number of Summer Typhoons Engendered over the Northwest Pacific and South China Sea and Main Climatic Conditions in the Preceding Winter and Spring          下载免费PDF全文

XIAO Ziniu  LIANG Hongli  LI Chongyin 《Acta Meteorologica Sinica》2010,24(4):441-451

Based on the monthly NCEP/NCAR reanalysis data, OLR (outgoing longwave radiation) data, and tropical cyclone data from the Typhoon Annual and Tropical Cyclone Annual edited by China Meteorological Administration, the relationship between the number of tropical cyclones (with the strongest wind ≥17 m s-1, including tropical storm, strong tropical storm, and typhoon, simply called typhoon in this paper)engendered over the Northwest Pacific and South China Sea in summer and the associated climate conditions is studied. First, the characteristics and di?erences of the climatic conditions between the years with more typhoons and those with fewer typhoons are compared. The results show that the summer typhoon has a close relationship with SST (sea surface temperature) and ITCZ (intertropical convergence zone) anomalies in the preceding winter and spring. With a La Niena like SST anomaly (SSTA) pattern in the preceding winter and spring, the ITCZ will move northwestward and be enhanced around 160°E in the equatorial central Pacific from the preceding winter to spring.The activity of the Pacific ITCZ is in general stronger and its location is more northward than usual, especially in the typhoon genesis region in West Pacific. This background is propitious to have more typhoons in summer. On the other hand, an El Nieno like SSTA pattern in the preceding winter will be companied with weaker ITCZ activities, and its location is more southward over the equatorial western Pacific from the preceding winter to spring; this background is propitious to have fewer typhoons in summer. In the year with more typhoons, the warm SST over West Pacific in the preceding winter provides a favorable condition for typhoon fromation in the following summer. It enhances the convergence in the troposphere and increases the water vapor supply to the warm SST region. In the following spring, the perturbation of the tropical ITCZ plays a more important role.When the ITCZ moves northward in spring, anomalous convergence will appear over the warm SST region and inspire the positive feedback between the large-scale moisture flux at low levels and the latent heat release in the atmosphere, which benefits the typhoon genesis in summer. Otherwise, if cold SST maintains over the northwestern Pacific during the preceding winter and spring, the convergence in the troposphere is disfavored and the water vapor supply to the cold SST region is reduced, which will bring about weaker ITCZ activities and the perturbation is lacking in the following spring. It then results in fewer summer typhoons.  相似文献   

两类不同月平均气温空间推算方法的对比     

张丹  邱新法  曾燕  钱茂 《气象》2010,36(12):80-85

利用全国660个常规气象站40年(1961-2000年)整编气象资料.采用逆距离权重反比法、样条函数法和普通克立格法等常用的3种插值方法,分析了直接插值法和综合余项法对气温插值的影响,提出了去除气温形成中的确定性部分后,以随机项进行插值可提高气温插值精度。并从空间上、时间上对比眲不同插值方法的误差,最后分析了气象站的空间分布密度对插值方法的敏感性。验证结果表明:除个别月份外,综合余项法的各项平均绝对误差均在1℃以内,比直接插值法减小了0.6～1.6℃,精度提高了38%～85%;且综合余项法的精度不依赖于台站密度的大小、插值方法的不同,具有较高的精确性和稳定性,这说明影响空间插值精度的关键因子并非是气象观测站点密度的提高、空问插值方法的改进。  相似文献   

A Case Study on a Quasi-Stationary Meiyu Front Bringing About Continuous Rainstorms with Piecewise Potential Vorticity Inversion          下载免费PDF全文

ZHAO Yuchun  LI Zechun  XIAO Ziniu 《Acta Meteorologica Sinica》2008,22(2):202-223

A 4-day persistent rainstorm resulting in serious flooding disasters occurred in the north of Fujian Province under the influences of a quasi-stationary Meiyu front during 5-8 June 2006. With 1°× 1° latitude and longitude NCEP reanalysis data and the ground surface rainfall, using the potential vorticity （PV） analysis and PV inversion method, the evolution of main synoptic systems, and the corresponding PV and PV perturbation （or PV anomalies） and their relationship with heavy rainfall along the Meiyu front are analyzed in order to investigate the physical mechanism of the formation, development, and maintenance of the Meiyu front. Furthermore, the PV perturbations related to different physics are separated to investigate their different roles in the formation and development of the Meiyu front. The results show： the formation and persistence of the Meiyu front in a quasi-WE orientation are mainly due to the maintenance of the high-pressure systems in its south/north sides （the West Pacific subtropical high/ the high pressure band extending from the Korean Peninsula to east of North China）. The Meiyu front is closely associated with the PV in the lower troposphere. The location of the positive PV perturbation on the Meiyu front matches well with the main heavy rainfall area along the Meiyu front. The PV inversion reveals that the balanced winds satisfying the nonlinear balanced assumption represent to a large extent the real atmospheric flow and its evolution basically reflects the variation of stream flow associated with the Meiyu front. The unbalanced flow forms the convergence band of the Meiyu front and it mainly comes from the high-pressure system in the north side of the Meiyu front. The positive PV perturbation related to latent heat release in the middle-lower troposphere is one of the main factors influencing the formation and development of the Meiyu front. The positive vorticity band from the total balanced winds is in accordance with the Meiyu front band and the magnitude of the posit  相似文献   

The Effects of Line-Wing Cutoff in LBL Integration on Radiation Calculations          下载免费PDF全文

ZHANG Hu  SHI Guangyu  LIU Yi 《Acta Meteorologica Sinica》2008,22(2):248-255

There are three basic methods in radiative transfer calculations, i.e., line-by-line (LBL) integration, correlated k-distribution method, and band model. The LBL integration is the most accurate of all, in which, there are two quadrature algorithms named in this paper as integration by lines and by sampling "points when calculating atmospheric transmittance in the considered wavenumber region. Because the LBL integration is the most expensive of all, it is necessary and important to save calculation time but increase calculation speed when it is put into use in the daily operation in atmospheric remote sensing and atmospheric sounding. A simplified LBL method is given in this paper on the basis of integration by lines, which increases computational speed greatly with keeping the same accuracy. Then, we discuss the effects of different cutoff schemes on atmospheric absorption coefficient, transmittance, and cooling rate under both of accurate and simplified LBL methods in detail. There are four cutoff schemes described in this paper, i.e., CUTOFFs 1, 2, 3, and 4. It is shown by this numerical study that the way to cut off spectral line-wing has a great effect on the accuracy and speed of radiative calculations. The relative errors of the calculated absorption coefficients for CUTOFF 2 are the largest under different pressures, while for CUTOFF 1, they are less than 2% at most of sampling points and for CUTOFFs 3 or 4, they are ahnost less than 5% in the calculated spectral region, however, the calculation time is reduced greatly. We find in this study that the transmittance in the lower atmosphere is not sensitive to different LBL methods and different cutoff schemes. Whereas for the higher atmosphere, the differences of transmittance results between CUTOFF 2 and each of other three cutoff schemes are the biggest of all no matter for the accurate LBL or for the simplified LBL integrations. By comparison, the best and optimized cutoff scheme is given in this paper finally.  相似文献