用数字滤波方法进行数值模式的初始化

将数字滤波原理用于Ｔ４２Ｌ９全球谱模式的初始化。选取两个初值进行了实验。通过对模式短时间积分得到的时间序列进行滤波处理，有效地滤去了初始场中的高频重力波振荡，保留了其中有天气意义的扰动，同时对分析场的改变很小。５ｄ预报的结果说明，经过初始化后的预报较为平稳，场较为光滑。对比实验表明，绝热和非绝热初始化的效果很接近。这种方法简便有效，是一种实用的初值化方法     

植被冠层多角度遥感研究进展

综述了近年来关于植被冠层多角度遥感研究的最新成果，分别讨论了二向性反射的正向模型和参量反演问题在理论和实际应用中的新进展。分析了卫星平台多角度遥感的应用前景及面临的困难，指出了未来多角度遥感研究的新方向。     

全球观测系统实地观测的内容和要求

全球性观测系统在检测，监测和预测地球系统的变化中发挥着越工重要的作用。地球系统的复杂性，多尺度性，非线性性，突变性，非平衡性等要求各种全球性观测系统之间必须加强联系与协调。评述了全球性观测系统联系与协调的发展趋势，并依据《全球性观测系统实地观测的内容和体系纲要》、介绍了全球性观测系统实地观测的内容和规范要求。     

Influence of the total atmospheric optical depth and cloud cover on solar irradiance components

Broadband solar irradiance data obtained in the spectral range 400–940 nm at Kwangju, South Korea from 1999–2000 have been analyzed to investigate the effects of cloud cover and atmospheric optical depth on solar radiation components. Results from measurements indicate that the percentage of direct and diffuse horizontal components of solar irradiance depend largely on total optical depth (TOD) and cloud cover. During summer and spring, the percentages of diffuse solar irradiance relative to the global irradiance were 5.0% and 4.9% as compared to 2.2% and 3.0% during winter and autumn. The diffuse solar irradiance is higher than the direct in spring and summer by 24.2%, and 40.6%, respectively, which may largely be attributed to the attenuation (scattering) of radiation by heavy dust pollution and large cloud amount. In cloud-free conditions with cloud cover ≤2/10, the fraction of the direct and diffuse components were 66.0% and 34.0%, respectively, with a mean daily global irradiance value of 7.92±2.91 MJ m⁻² day⁻¹. However, under cloudy conditions (with cloud cover ≥8/10), the diffuse and direct fractions were 97.9% and 2.2% of the global component, respectively. The annual mean TOD under cloudless conditions (cloud cover≤2/10) yields 0.74±0.33 and increased to as much as 3.15±0.67 under cloudy conditions with cloud amount ≥8/10. An empirical formula is derived for estimating the diffuse and direct components of horizontal solar irradiance by considering the total atmospheric optical depth (TOD). Results from statistical models are shown for the estimation of solar irradiance components as a function of TOD with sufficient accuracy as indicated by low standard error for each solar zenith angle (SZA).     

The possible connection between ionization in the atmosphere by cosmic rays and low level clouds

Recent analysis of monthly mean cloud data from the International Satellite Cloud Climatology Project uncovered a strong correlation between low cloud and the cosmic ray flux for extensive regions of the Earth. Additional data have been recently released covering the period up to September 2001 with which we have made a new study of the geographical variation of the correlation between low cloud and predicted ionization level from cosmic rays at an altitude of 2 km. When analysed globally, we find that the correlations do not correspond to the latitude variation of cosmic ray flux and they are not field significant. Nonetheless they appear to be marginally field significant over broad latitude and longitude bands with a peak positive correlation at 50 degrees North and South and a tendency to negative correlation at lower latitudes. The correlation is strongest over the North and South Atlantic. Several of these features are consistent with the predictions of the electroscavenging process.We use a simple model to calculate the climatic impact should the correlation be confirmed. We show that, under the most favorable conditions, a reduction in low cloud cover since the late 19th century, combined with the direct forcing by solar irradiance can explain a significant part of the global warming over the past century, but not all. However, this computation assumes that there is no feedback or changes in cloud at other levels.     

航天GPS接收机设计

航天GPS接收机为航天器提供航迹、姿态、时问和相对距离等导航信息，提高航天嚣运行的自主性。文中介绍了清华宇航中。航天GPS接收的硬件和软件设计，给出测试结果和分析。     

自动气象站雨量资料的获取与转换

分析了自动气象站分钟雨量资料获取与转换的必要性,介绍了雨量资料获取的思路与具体方法.通过这种方法,实现了商丘市所有自动气象站雨量资料的共享,并与GPRS、GSM乡级自动雨量站资料进行融合.     

IGGOS as a potential partner in IGOS

This short note reviews our thinking on how IGGOS can best achieve a high status within the set of global monitoring programmes. If such a high status can be obtained, then the importance of geodetic networks and services will be recognized more widely, and their activities will consequently be better resourced in the long term. One particular aspect concerns how IGGOS can complement the roles of the various IGOS partners within global monitoring. The different ways in which IGGOS can contribute to IGOS are outlined.     

The GGOS as the backbone for global observing and local monitoring: A user driven perspective

A key geodetic contribution to both the three Global Observing Systems and initiatives like the European Global Monitoring for Environment and Security is an accurate, long-term stable, and easily accessible reference frame as the backbone. Many emerging scientific as well as non-scientific high-accuracy applications require access to an unique, technique-independent reference frame decontaminated for short-term fluctuations due to global Earth system processes. Such a reference frame can only be maintained and made available through an observing system such as the Global Geodetic Observing System (GGOS), which is currently implemented and expected to provide sufficient information on changes in the Earth figure, its rotation and its gravity field. Based on a number of examples from monitoring of infrastructure, point positioning, maintenance of national references frames to global changes studies, likely future accuracy requirements for a global terrestrial reference frame are set up as function of time scales. Expected accuracy requirements for a large range of high-accuracy applications are less than 5 mm for diurnal and sub-diurnal time scales, 2–3 mm on monthly to seasonal time scales, better than 1 mm/year on decadal to 50 years time scales. Based on these requirements, specifications for a geodetic observing system meeting the accuracy requirements can be derived.