Radiative transfer in spherical shell atmospheres: I. Rayleigh scattering

A comparison is made between the plane-parallel approximation and the more realistic spherical shell approximation for the radiance reflected from a planetary atmosphere. In this paper we have considered a planet of radius 6371 km (the Earth) with a homogeneous, conservative, Rayleigh scattering atmosphere extending to a height of 100 km. We have found significant departures from the plane-parallel approximation. Radiance versus height distributions for both single and multiple scattering are presented. Results are presented for the fractional radiance from altitudes in the atmosphere which contribute to the total unidirectional reflected radiance at the top of the atmosphere. We have referred to this as the radiance versus height distribution in the sequel. These data will be very useful for both remote sensing applications and planetary spectroscopy. We have also found that gross violations of the principle of reciprocity do occur in the spherical shell approximation.     

A technique to deduce atmospheric temperature and constituent profiles from a planet's limb radiance profile

The concept is described of deducing the temperature and constituent profile of a planetary atmosphere from orbiter measurements of the planet's ir limb radiance profile. Expressions are derived for the weighting functions associated with the limb radiance profile for a Goody random band model. Analysis of the weighting functions for the Martian atmosphere indicates that a limb radiance profile in the 15 μm CO₂ band can be used to determine the Martian atmospheric temperature profile from 20 to 60 km. Simulation of the Martian limb radiance profile in the rotational water vapor band indicates that Martian water vapor mixing ratios can be inferred from limb radiance observations in a water vapor band.     

EUV analysis of an active region

A sequence of extreme ultraviolet (EUV) spectroheliograms of McMath region No. 10283 were obtained by the Harvard College Observatory experiment on OSO-6. The lines Ovi λ1032 Mg × λ625, Si xii λ499 and Fe xvi λ 335 were used to determine coronal temperatures and densities above the active region. A comparison of theoretical and observed line ratios yielded coronal temperatures of 2.2 to 2.3 × 10⁶K above the active region and 2.0 to 2.1 × 10⁶K in the surrounding area. The temperatures derived from ratios involving the O vi intensities are systematically higher than the others. This is attributed to an error in the theoretical O vi intensities. The intensities observed above the limb are compared with intensities predicted with a simple model based on cylindrical geometry. The overall agreement shows that the assumption of an iso-thermal corona in hydrostatic equilibrium above the active region is a reasonable working hypothesis and that the adopted geometrical model for the electron density distribution is adequate.     

One- and multi-component models of the upper photosphere based on molecular spectra

Non-LTE synthetic spectra derived from a detailed analysis of the formation of the CN (0, 0) λ13883 Å spectrum are compared with center-limb photoelectric spectra taken at Kitt Peak National Observatory. Kitt Peak National Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. Significant non-LTE effects are found and the Kurucz, Altrock-Cannon, Mount-Linsky II, and HSRA models are compared. We derive a solar carbon abundance of A _c =8.30±0.10 for the Mount-Linsky model and A _c =8.40±0.10 for the Altrock-Cannon model, compared to the HSRA value of A _c =8.55±0.10, assuming a nitrogen abundance of logA _N=7.93. In addition we specify the regions of formation for the CN(0, 0) 3883.35 Å bandhead at disc center and limb.     

Memories of Fire: Eduardo Galeano and the Geography of Guatemala

In Memory of Fire, a poetic narration of the history of the Americas from pre-Columbian times to the late 20th century, Eduardo Galeano furnishes readers with over 1200 of his trademark vignettes, some 35 of which pertain to Guatemala. Galeano evokes disparate aspects of the geography of Guatemala, past and present, in grounded miniatures of time, place, and episode. His sketches of the experiences of Maya peoples allow us to see them as survivors of three cycles of conquest: (1) conquest by imperial Spain; (2) conquest by local and international capitalism; and (3) conquest by state terror. Composed in the literary mode of creative non-fiction, Memory of Fire serves as an inspirational classroom text, exposing students not only to factual detail but also a powerful artistic imagination.     

Detrital zircon reference for the North China block

U–Pb analyses of 250 single detrital zircons from Upper Proterozoic to Ordovician strata collected from the Zhuozi Shan in north-central China provide a detrital zircon reference for the North China block, a major crustal entity in the Asian tectonic collage. The results, which range in age from 1.72 to 2.97 Ga, shed new light on the age of the crystalline basement in North China, much of which is covered by younger sedimentary units. In addition, this detrital zircon reference can be used to help determine the provenance of clastic sedimentary units and for assessing validity of paleogeographic and regional tectonic models that include the complex history of Asian continental amalgamation, terrane accretion, and subsequent translation that is ongoing today.     

东南沿海地震活动特征量

1970年以来,东南沿海地区经历了上世纪末以来明显的第Ⅴ活跃幕(或轮回)平静和活跃时段,本文通过分析研究这两个时段地震活动在时空强上的差异性,定量提取其活动演化过程参量,为该区未来地震活动期判定提供相对定量的参考依据。     

多时相组合分类法在土地利用动态监测中的应用

介绍了土地利用遥感动态监测的基本概念，简述了遥感土地利用变化信息提取等遥感监测方法．重点探讨了多时相组合分类方法的相关技术。对广西2002年和2003年两个时相的MODIS数据．采用多时相直接分类法对土地利用变化状况进行了遥感动态监测。对不同方式波段组合的试验表明。经过差值、比值处理的波段组合具有较差的试验效果(总体精度只有30％～40％)，而经过PCA变换的波段组合则具有相对较好的试验效果(总体精度超过70％)。     

内蒙古东胜砂岩型铀矿后生成矿与油气关系

发育于内蒙古鄂尔多斯盆地北部中侏罗统直罗组辫状河相杂砂岩体内的砂岩型铀矿，有一系列较为特殊的与放射性铀成矿有直接或间接关系的成矿地质现象：绿色化蚀变带、漂白退色化带、二次胶结钙化砂岩团块及钙化砂岩断续层与“钙化木”后生蚀变现象；在与铀矿化和与油气的关系认识上存在一定分歧。初步分析了它们的形成、成因及与铀成矿的关系及其找矿意义。