A design study for an advanced ocean color scanner system

The spaceborne ocean color scanners currently being planned for flights on Nimbus-G satellite or space shuttle craft are, in every aspect, only a modest beginning towards what is to be expected of ocean color scanners in the eighties. Improvements are necessary in the following areas: present systems provide a spatial resolution on the order of 1 km at nadir, which would not satisfy most of the coastal zone study requirements. Also the present design of radiomers is less than optimum for the removal of the atmospheric effects on ocean colorimetry.Along with a colorimetric data analysis scheme, the instrumental parameters which need to be optimized in future systems are outlined. One technique for meeting these requirements entails use of large linear array detector technology.     

Snow and cloud feedbacks modelled by an atmospheric general circulation model

One of the most important parametrizations in general circulation models used for climate change experiments is that of the surface albedo. The results of an albedo feedback experiment carried out under the auspices of the US Department of Energy are presented. An analysis of long and short wave components of the model response shows that short wave response dominates changes in fixed to variable albedo experiments, but that long wave response dominates in clear to cloudy sky changes. Cloud distribution changes are also discussed and are related to changes in global sensitivity. At the surface, the heat balance change for perturbed sea surface temperatures is dominated by changes in latent heat flux and downward long wave radiation. If albedo is freed up however, the major contrast lies in the change in surface reflected short wave radiation, amplified by changes in downward short wave radiation caused by cloud amount changes.     

The recording of Pc1 geomagnetic pulsations using a microcomputer preprocessing system

In the past slow-speed frequency-modulated analogue tape recording techniques have provided the most convenient method for recording ground-based Pc1 pulsation data on a continuous basis. With events occurring often only a few hours in a week, and a Nyquist frequency of 4–5 Hz, direct digital recording is not practical because of the bulk of data accumulated. However, with the recent availability of reasonably priced microcomputers and advanced signal processing techniques it is now possible to preprocess digital data in the field and store only events of interest. A two-component induction coil magnetometer incorporating a Z80 based 64K RAM microcomputer-floppy disk preprocessing system is described. It is capable of recording Pc1 signals in the 0.2–4 Hz band at middle-to-low latitudes with a minimum detectable signal level of 3 pT. The reliability and limitations of the preprocessing techniques utilizing FFT autospectral analysis to recognize Pc1 signals are discussed.     

Willingness to pay for marine-based tourism in the Ponta do Ouro Partial Marine Reserve,Mozambique

Marine and coastal ecosystems face widespread degradation largely because market failure hides the economic value of the goods and services they provide. Marine protected areas (MPAs) can serve as structures that ensure the continued functioning of marine and coastal ecosystem goods and services. Yet, to be effective and sustainable, MPAs must be able to prove their economic worth and generate revenue. User-fee systems are used commonly to partially finance multi-use MPAs. This study applies contingent valuation as a method of economic valuation within an MPA in southern Mozambique. Using a payment card and questionnaire from November 2012 to April 2013, this study determined the willingness to pay (WTP) of three user groups for access to the Ponta do Ouro Partial Marine Reserve. The study also investigated the potential for the reserve to increase revenues for conservation through the implementation of a user fee for marine-based activities. Probit and ordinary least squares (OLS) regressions were used to determine the effects of various independent variables on WTP. The OLS model found income, African residency and environmental awareness to be significant factors that influenced visitors' WTP for access to the reserve. The mean WTP was R 43.75 (South African rands) per person per day. Using data supplied by the reserve management, conservative estimated annual revenues based on the implementation of this fee amount ranged between R 1.46 million and R 3.3 million.     

Io's surface composition based on reflectance spectra of sulfur/salt mixtures and proton-irradiation experiments

The available full-disk reflectance spectra of Io in the range 0.3 to 2.5 μm have been interpreted by comparison with new laboratory spectra of a wide variety of natural and synthetic mineral phases in order to determine a surface compositional model for Io that is consistent with Io's other known chemical and physical properties. Our results indicate that the dominant mineral phases are sulfates and free sulfur derived from them, which points toward a low temperature and initially water-rich surface assemblage. Our current preferred mineral phase mixture that best matches the Io data and is simultaneously most consistent with other constraints, consists of a fine-grained particulate mixture of free sulfur (55 vol%), dehydrated bloedite [Na₂Mg(SO₄)₂·xH₂O] (30 vol%) ferric sulfate [Fe₂(SO₄)₃·xH₂O] (15 vol%), and trace amounts of hematite [Fe₂O₃]. Other salts may be present, such as halite and sodium nitrate, as well as clay minerals. Such a model is consistent with a probable pre- and post-accretion thermal history of Io-forming material and Io's observed Na emission and other properties. These results further support the evaporite surface hypothesis of Fanale et al'; while not precluding the presence of certain silicate phases such as montmorillonite.The average surface of Io's leading hemisphere appears to contain less free sulfur and more salts and to be finer grained than that of the trailing hemisphere. Since Io is immersed in Jupiter's magnetosphere, irradiation damage effects from low-energy proton bombardment were studied. Irradiation damage of lattices is estimated to be a relatively minor but operative process on the surface of Io; irradiation darkening by sulfate reduction to free sulfur and by F-center production in salts may be partly responsible for the differences in albedo of leading and trailing hemispheres and equatorial and polar regions of Io, but slight regional differences in relative intrinsic phase concentration on the surface may likewise account for these global variations in albedo.Possible unusual surface properties predicted by this model include: posteclipse darkening in certain wavelenghts, limb brightening in certain wavelengths, and unusual surface electrical properties. Further refinement of Io's surface composition model and better understanding of surface irradiation effects will be possible when observational data in the range 0.20 to 0.30 μm are obtained and when improved spectra in the range 0.30 to 5.0 μm are obtained having increased spectral, spatial, and temporal resolution.     

坦桑尼亚西嘎山地区金矿床地质特征及找矿方向

西嘎山(Siga Hills)地区位于维多利亚湖南部绿岩带上,该地区金矿床大多属绿岩带条带状铁建造(BIF)型金矿,金矿床赋存于条带状铁建造(BIF)中,矿体受"岩性+构造"双重控制。磁法测量显示马黑加矿区M1、M2、M3三条磁异常带,异常由条带状含铁建造和金矿体共同引起;土壤地球化学测量显示Au与As、Sb具有显著相关性。综合对比区域金矿信息,提出马黑加金矿化带南北延长线及其东部与花岗岩接触带、西嘎山南北走向带、西嘎山与马黑加之间等3个区域为今后西嘎山地区的找矿方向。     

秋季抚仙湖湖滨带大型底栖动物生态学研究

2011年秋季对抚仙湖水域10个站位进行大型底栖动物的采样调查,研究了该湖泊湖滨带底栖动物的群落结构。共鉴定底栖动物10个分类单元,其中水生昆虫类和软体动物等主要类群分别为1种和6种,各占总物种数的10%、60%。主要优势种为拟沼螺、日本沼虾。调查区底栖动物的密度介于26～229ind/m2之间,平均值为97.9ind/m2。生物量介于0.96～15.69g/m2之间,平均值为6.77g/m2。香农-威纳多样性指数介于0～1.45之间,平均值为0.82。     

基于随机森林模型的西藏人口分布格局及影响因素

在乡镇尺度下厘清人口分布格局及其影响因素与区域差异,对在生态脆弱区制定可持续发展政策具有重大指导意义。基于2010年西藏自治区的乡镇尺度人口普查数据,提取人口密度和空间因子,利用空间统计方法分析了人口分布的疏密特征和集聚特征,对比运用多元线性回归方法和随机森林回归方法探索该地区人口分布的影响因素及其区域差异。结果表明：① 西藏乡镇人口密度在空间上表现出极强的非均衡性,其总体趋势是东南高西北低,高密度区与大江大河及主要交通干线具有较强的空间耦合性;② 大致以波绒乡（聂拉木县）—岗尼乡（安多县）为西藏的人口分界线,人口集聚的“核心—边缘”特征明显;③ 多元线性回归方法中,人造地表指数对人口分布的影响程度最大,随后依次为夜间灯光指数和路网密度;④ 利用随机森林方法进行的人口密度预测比多元线性回归方法精度高,可以用来对影响因子的重要性进行排序;排序在前六位的影响因子由高到低依次为夜间灯光指数、人造地表指数、路网密度、工业总产值、GDP和多年平均气温,它们与人口密度均呈正相关关系;地形地貌要素中以海拔和坡度的贡献率最大且与人口密度均呈负相关关系;⑤ 西藏人口分布格局的影响因素及其相互作用呈现出明显的区域差异特征,河谷是西藏地区人口的集聚区,主要分布在拉萨河谷、年楚河谷以及三江河谷;⑥ 通过随机森林回归分析,可以利用概念模型来表达人口分布影响因素,将主导因素概括为土地利用结构、道路通达度及城镇化水平。     

Regolith-atmosphere exchange of water and carbon dioxide on Mars: Effects on atmospheric history and climate change

Exchange of CO₂ and H₂O between the Mars regolith and the atmosphere-cap system plays an important role in governing the evolution of the martian atmosphere and the martian climate. Most of the exchangeable CO₂ (perhaps one or two orders of magnitude more than the atmospheric inventory) is currently adsorbed on the deep regolith, and can be “cryopumped” to a large quasipermanent CO₂ cap (not now present) during lowest Mars obliquity (θ). During the obliquity driven regolith-cap CO₂ exchange cycle, the atmospheric pressure varies harmonically between ~0.1 mb (lowest Θ) and ? 20 mb (highest Θ). The regolith buffer plays only a small or negligible role in the seasonal CO₂ pressure variations caused by atmosphere-cap exchange because adsorption greatly inhibits diffusion of the seasonal “pressure wave” into the regolith. In contrast, thermally driven H₂O seasonal exchange between the atmosphere and regolith appears to be in large part responsible for observed seasonal variations in the small atmospheric H₂O inventory. Long term exchange of H₂O may be dominated by transfer between the polar caps and ice in the regolith. Available and potential tests of regolith-atmospheric-cap volatile exchange models using ground-based and spacecraft-based techniques are discussed.