A new treatment of the albedo radiation pressure in the case of a uniform albedo and of a spherical satellite

The purpose of this paper is to present a model for the radiation pressure acceleration of a spherical satellite, due to the radiation reflected by a planet with a uniform albedo. A particular choice of variables allows one to reduce the surface integrals over the lit portion of the planet visible to the satellite to one-dimensional integrals. Exact analytical expressions are found for the integrals corresponding to the case where the spacecraft does not "see" the terminator. The other integrals can be computed either numerically, or analytically in an approximate form. The results are compared with those of Lochry (1966). The model is applied to Magellan, a spacecraft orbiting Venus.     

中国古代常规日食记录的整理分析

收集并分析了公元前8世纪到公元15世纪的中国古代密集、简略而公式化的日食记录。基于这些记录整理成一个包括938条日食记录的计算机可读形式的“常规日食记录表”。该表给出每次记录的原日期、公历日期、当时首都、所属朝代以及一部分记录所载的进一步详情。对该表的构成作了介绍,并对这些历史记录进行了初步的分析和归纳。     

In situ time resolved synchrotron powder diffraction study of thaumasite

Structural changes during dehydration and subsequent decomposition in thaumasite Ca₃Si(SO₄)(CO₃)(OH)₆·12 H₂O were studied by in situ synchrotron powder diffraction between 303 and 1,098 K. Evolution of the crystal structure was observed through 28 structure refinements, by full profile Rietveld analysis performed in the P6₃ space group, between 300 and 417 K, whereupon the thaumasite structure was observed to breakdown. Within this temperature range, the cell parameters of thaumasite increased as a function of temperature in a nearly linear fashion up to about 393 K, at which temperature, a slight slope change was observed. Above 400 K, the thermogravimetric analysis revealed that the dehydration process proceeded very rapidly while the refined occupancy of water molecules dropped below a critical level, leading to instability in the thaumasite structure. At a same time, a remarkable change in the unit cell parameters occurring at about 417 K indicated that the crystal structure of thaumasite collapsed on losing the crystallization water and it turned amorphous. This result indicated that the dehydration/decomposition of thaumasite was induced by the departure of the crystallization water. At about 950 K, anhydrite and cristobalite crystallized from the thaumasite glass.     

A geochronological approach to understanding the role of solar activity on Holocene glacier length variability in the Swiss Alps

We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight presentday mid‐latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon‐dated periods defined with less extensive glaciers coincide with periods of reduced radio‐production, pointing to a connection between solar activity and glacier melting processes. Measured long‐term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long‐term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances.     

Retrieval of stratospheric O3 and NO2 vertical profiles using zenith scattered light observations

Daily zenith scattered light intensity observations were carried out in the morning twilight hours using home-made UV-visible spectrometer over the tropical station Pune (18‡31′, 73‡51′) for the years 2000–2003. These observations are obtained in the spectral range 462–498 nm for the solar zenith angles (SZAs) varying from 87‡ to 91.5‡. An algorithm has been developed to retrieve vertical profiles of ozone (O₃) and nitrogen dioxide (NO₂) from ground-based measurements using the Chahine iteration method. This retrieval method has been checked using measured and recalculated slant column densities (SCDs) and they are found to be well matching. O₃ and NO₂ vertical profiles have been retrieved using a set of their air mass factors (AMFs) and SCDs measured over a range of 87–91.5‡ SZA during the morning. The vertical profiles obtained by this method are compared with Umkehr profiles and ozonesondes and they are found to be in good agreement. The bulk of the column density is found near layer 20–25 km. Daily total column densities (TCDs) of O₃ and NO₂ along with their stratospheric and tropospheric counterparts are derived using their vertical profiles for the period 2000–2003. The total column, stratospheric column and tropospheric column amounts of both trace gases are found to be maximum in summer and minimum in the winter season. Increasing trend is found in column density of NO₂ in stratospheric, tropospheric and surface layers, but no trend is observed in O₃ columns for above layers during the period 2000–2003     

新疆塔里木河流域平原区土地利用覆盖变化及其对生态环境影响分析

分析了塔里木河流域平原区近十余年土地利用覆盖变化和用水量的变化情况,对两者间的关系进行了研究,提出了为防止生态环境进一步恶化应采取的对策.     

基于立体补偿的遥感立体像对压缩方法

提出研究遥感立体像对的压缩问题。主要讨论了左右影像的视差补偿和辐射补偿。针对遥感立体像对视差分布不均以及左右影像存在辐射差的特点,提出了一种基于立体补偿的遥感立体像对压缩算法。该算法以左片为基准图像,采用自适应视差估计计算出右片的视差矢量,结合辐射校正和重叠块视差补偿技术得到平滑的右片的预测图像,以右片减去预测图像得到残差图像,然后采用小波压缩算法对残差图像进行压缩。实验结果表明,该算法能显著提高遥感立体像对的压缩性能。     

五道梁地区总辐射的年际变化

利用实测的太阳总辐射通量密度及地气温差资料，建立了月平均地气温差与月平均太阳总辐射通量密度的回归方程，并用该回归方程计算了五道梁地区1980-1993年共14年的月平均总辐射通量密度，分析了该地区总辐射通量密度的年际变化，发现该地区总辐射通量密度具有较明显的6～7年的振荡周期。20世纪后10年年平均总辐射通量密度有增大的趋势。     

青藏高原云-辐射-加热效应和南亚夏季风--1985年与1987年对比分析

文中首先利用NCEP NCAR再分析的风场资料 ,分析了南亚夏季风的时空特征 ,选取了有代表性的典型强、弱夏季风年 ,继而利用ISCCP C2、ERBE S4卫星观测资料和NCEP NCAR再分析资料 ,对比分析了强、弱夏季风前期青藏高原地区的云—辐射—加热状况及其在海、陆差异中的作用。分析结果表明 ,南亚夏季风强或弱 ,其前期青藏高原地区的云—辐射—加热效应有明显的差异。在强 (弱 )南亚夏季风的前期 ,青藏高原大部分地区为相对少 (多 )云区 ,其云量变化不仅表明了此区的云—辐射—加热效应的不同 ,更重要的是与此同时出现的海、陆之间云量分布的“跷跷板”现象 ,进一步改变了海、陆之间的热力差异。而且 ,在强南亚夏季风年 ,这种热力差异不但开始得早 ,而且持续时间长、作用范围大 ,从而对南亚夏季风的形成和变化产生重要的影响     

ARTIFICIAL NEURAL NETWORK CORRECTION OF ROUGH ERRORS OF OBSERVATIONS

In the context of tower measured radiation datasets.following the correction principle meetinga diagnostic equation in data quality control and in terms of a technique for model construction ondata and ANN(artificial neural network)retrieval for BP correction of radiation measurementswith rough errors available,a BP model is presented.Evidence suggests that the developed modelworks well and is superior to a convenient multivariate linear regression model,indicating its wideapplications.