Comparison of Backscatter Ultraviolet (BUV) and ground-based total ozone fields for December 1970

For the period December 1970, comparison is made between the monthly average analyses (mapped fields) of the Backscatter Ultraviolet (BUV) total ozone data and the ground-based observations. In particular, significant differences of over 50 Dobson units are noted over the region of the North Atlantic Ocean with the BUV of greater magnitude than the ground-based data. As part of the overall verification program, both analyses are compared against the 100 mb height fields. The results indicate that the BUV analysis in the region of question is the more consistent of the two.     

Stratospheric response to chemical perturbations

The paper presents a coupled chemical-radiative one-dimensional model which is used to assess the steady-state and time-dependent composition and temperature changes in relation to the release in the atmosphere of chemicals such as CO₂, N₂O, CH₄, NO _x and chlorofluorocarbons.The model indicates that a doubling in CO₂ leads to an increase in temperature of 12.7 K near the stratopause and to an increase in total ozone of 3.3% with a local enhancement of 17% at 40 km altitude. Additional release of N₂O leads to an ozone reduction in the middle stratosphere. The reduction in the ozone column is predicted to be equal to 8.8% when the amount of N₂O is doubled. The chemical effect of CH₄ on ozone is particularly important in the troposphere. A doubling in the mixing ratio of this gas enhances the O₃ concentration by 11% at 5 km. The predicted increase of the ozone column is equal to 1.4%. A constant emission of CFCl₃ (230 kT/yr) and CF₂Cl₂ (300 kT/yr) leads to a steady-state reduction in the ozone column of 1.9% compared to the present-day situation. The effect of some uncertainties in the chemical scheme as well as the impact of a high chlorine perturbation are briefly discussed.Finally the results of a time dependent calculation assuming a realistic scenario for the emission of chemical species are presented and analyzed.     

气象卫星云图数据的高效无失真压缩

在综合分析气象卫星云图数据高效无失真压缩方法的基础上，将二维DPCM预测器加反射型熵编码器用于各种灰度类型的气象卫星云图的无失真压缩，使压缩比与运算速度得到了较好的折中，实用效果较好。     

地震监测预报中的卫星遥感（热红外）图象处理

叙述了用于地震监测预报中的卫星遥感（热红外）图象处理的原理、方法，分析了图象处理的特征，通过实例对图象处理进行了说明，指出了存在的问题     

测高卫星径向摄动的时域表示

本文首先推导出了量级为ｅ＾｜ｑ｜的Ｇｌｐｑ（ｅ）的显式表达式，给出了Ｇｌｐｏｐ、Ｇｌｐ１和Ｇｌｐ－１和保留至ｅ＾｜ｑ｜＋２项的高阶公式，然后给出了与Ｋａｕｌａ线性解形式相类似的保留至ｅ＾２项的径向摄动公式，最后给出了径向摄动频率与轨道元素摄动频率之间的对应关系。     

南极1∶20万大剖面卫星影像数字制图

本文论述了在缺少地面控制点的情况下，进行南极卫星影像数字制图的方法和技术。利用ＴＭ和ＭＳＳ卫星影像数据，制作了从中山站至南极点大剖面考察区内的１∶２０万卫星影像图。南极景观以冰雪地貌为主，冰雪在卫星影像上亮度极大，反差极小，导致条带噪声干扰严重。另一方面，裸岩地、海水与冰雪之间的反差又过大，细貌被压抑，这些又给影像处理造成很大困难，针对这些特点，本文叙述了从影像中提取噪声谱后利用方向滤波法消去条带噪声。基于自动识别理论进行分类增强，采用相关匹配和加权平滑法进行不同时期卫星影像镶嵌等几项特殊处理技术。     

汶川地震灾区影像地图的研制

结合汶川地震期间分县、1：25000和1：5000应急影像地图的设计与生产,对一些相关技术进行了试验和总结,可为今后影像地图的研制提供理论和方法上的参考。     

Effects of topographic–isostatic masses on gravitational functionals at the Earth’s surface and at airborne and satellite altitudes

Topographic–isostatic masses represent an important source of gravity field information, especially in the high-frequency band, even if the detailed mass-density distribution inside the topographic masses is unknown. If this information is used within a remove-restore procedure, then the instability problems in downward continuation of gravity observations from aircraft or satellite altitudes can be reduced. In this article, integral formulae are derived for determination of gravitational effects of topographic–isostatic masses on the first- and second-order derivatives of the gravitational potential for three topographic–isostatic models. The application of these formulas is useful for airborne gravimetry/gradiometry and satellite gravity gradiometry. The formulas are presented in spherical approximation by separating the 3D integration in an analytical integration in the radial direction and 2D integration over the mean sphere. Therefore, spherical volume elements can be considered as being approximated by mass-lines located at the centre of the discretization compartments (the mass of the tesseroid is condensed mathematically along its vertical axis). The errors of this approximation are investigated for the second-order derivatives of the topographic–isostatic gravitational potential in the vicinity of the Earth’s surface. The formulas are then applied to various scenarios of airborne gravimetry/gradiometry and satellite gradiometry. The components of the gravitational vector at aircraft altitudes of 4 and 10 km have been determined, as well as the gravitational tensor components at a satellite altitude of 250 km envisaged for the forthcoming GOCE (gravity field and steady-state ocean-circulation explorer) mission. The numerical computations are based on digital elevation models with a 5-arc-minute resolution for satellite gravity gradiometry and 1-arc-minute resolution for airborne gravity/gradiometry.     

基于卫星降水和WRF预报降水的“6.18”门头沟泥石流事件的回报检验研究

2017年6月18日北京门头沟地区突发泥石流,造成6人伤亡。短时强降水是这起事件的主要诱发因素,但常规气象观测并没有很好地观测到此次降水过程,可见降水数据的准确性对于滑坡泥石流的实时预警及预报至关重要。近年来,卫星遥感估算降水发展迅速,WRF（Weather Research and Forecasting Model）模式关于降水的预报技巧也逐渐提高。本文以自动站降水资料为参考,首先利用定性方法和泰勒图、TS（Threat Score）评分等定量的方法比较了CMORPH（CPC MORPHing technique）、GPM（Global Precipitation Measurement）和PERSIANN-CCS（Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System）三种卫星降水资料以及不同起报时间的WRF预报降水对此次降水过程的表现能力,然后利用降水数据驱动滑坡泥石流统计预报模型,对此次事件进行了回报,分析不同降水数据在模型中的实际应用效果,最终为滑坡泥石流实时预警和预报系统的构建提供参考。结果表明,三种卫星降水资料基本上能反映出此次降水过程东北—西南向的带状空间分布形态,其中,CMORPH与自动站资料的空间相关性最好,命中率也最高,但对降水量有一定的高估,GPM对平均降水量的时间变化有较好的反映,体现了卫星降水在观测较少地区的良好利用价值,PERSIANN-CCS的表现则相对差些。WRF模式能预报出此次降水的带状空间分布特征,但降水中心的位置与实际有所偏差;此外,预报的最大降水量的峰值出现时间比实际上晚。由于此次降水的强局地性,只有空间分辨率均匀且质量相对较好的CMORPH卫星降水驱动模型可以回报出此次事件,而自动站点资料由于空间分布不均,则没有回报出此次事件,这表明了卫星降水在滑坡泥石流实时预警系统的构建中具有一定的优势。WRF模式降水驱动模型可以提前做出预警,虽然预报的事件发生时间与实际相比偏晚3~5 h,但WRF可以较好地预报72 h内的降水,因而可以延长灾害的可预见期。WRF模式预报降水的时间和空间精度都需要进一步提高,但是仍具有很好的参考意义。     

基于GNSS的MODIS大气可降水量校正模型

MODIS大气可降水量（PWV）空间分辨率高但易受云雨等环境因素影响,精度不高.GNSS PWV 空间分辨率较低但具有全天候、不受天气影响、精度高的优点.研究表明两者存在显著的线性相关性,结合两者的优点,基于GNSS PWV校正MODIS PWV可获取大面积高精度的PWV.针对传统的线性回归校正模型没有考虑云、气溶胶等的影响使两种数据线性相关性变差的问题,本文在传统的线性校正模型上增加了使用年积日的非线性周期项的方法来构建校正模型.利用2017—2019年香港地区GNSS对流层延迟与MODIS近红外数据,使用频谱分析线性残差项,结果表明残差具有显著的年周期.对比传统模型,本文模型的平均绝对误差、平均相对误差、均方根误差和拟合度都有明显的改善,表明本文模型可行有效且精度较高.