卫星对地观测中大气与地表辐射贡献的参数化

卫星对地观测定量遥感地表与大气特性是当前地球科学与应用研究的关键手段之一。在定量遥感中区分大气和地表在地-气系统对空间散射辐射中各自的贡献与作用是关键的一步。这一问题的核心是基于辐射传输方程的数值计算建立起适合应用于遥感反演中分离大气与地表贡献的参数化表达式。本文对特定的气溶胶气候类型和可见/近红外波段建立起定量的表达形式,并对表达式的物理含义和拟合精度进行了分析。最后讨论了其应用的可行性和进一步的工作。     

山东枣庄地区辐射逆温及其影响

本文运用1981年11月17日-12月16日共30天实地考察资料,分析了山东枣庄地区冬季辐射逆温时空变化规律。并探讨了辐射逆温的生成与云量、风速的关系。     

应用遥感图像提取煤层自燃信息时必须考虑的几个影响因素

煤层自燃是中国北方煤田中普遍存在的灾害现象,它不但烧掉了大量的煤炭资源,而且还污染了环境。实践证明,利用遥感影像判别火区位置、圈定火区范围和对火区进行动态监测,及时为灭火工程提供信息,是一项经济和社会意义很大的工作。由于受多种因素的制约,不同地区、不同波段、不同时相、不同空间分辨率的遥感图像,其影像特征（含与煤层自燃有关的热异常影像特征）都有较大的差异,因而从图像上分析和提取地物的热红外辐射特征时,需要考虑遥感图像类型、成像时间、地形条件、气象条件和岩性特征等因素的影响。本文着重讨论了地表辐射温度与上述各项因素之间的关系。     

Optimized Computation of Transfer Coefficients in Surface Layer with Different Momentum and Heat Roughness Lengths

A new method for computing the surface transfer coefficients is proposed, based on state-of-the-art empirical flux-profile relationships. The influence of the roughness length ratio is first demonstrated with the classical iterative calculation method. Then a non-iterative algorithm is developed, taking into account the difference between momentum and heat roughness lengths.The new method is validated by comparison with the reference iterative computation. The large gain-in computer processing time (CPU) time gain for the calculation of surface fluxes in Eulerian grid models is finally assessed.     

Meteorological Aspects, Ozone, and Solar Radiation Measurements During POPCORN 1994

Meteorological data, ozone mixing ratios, and photolysis frequencies for the period August 2 to August 24, 1994, are presented and discussed in support of the field campaign POPCORN (Photochemistry of Plant Emitted Compounds and OH Radicals in Northeastern Germany). Measurements of temperature, ozone, and wind speed at different heights are used to evaluate micro-meteorological parameters. The observations provide information about local influences on the air mass composition. The analysis of radio sonde data of nearby stations provides the height of the planetary boundary layer.     

CONCENTRATION AND FLUX OF CO2, TURBULENCE FLUXES AND RADIATION BALANCE IN THE NEAR SURFACE LAYER OVER WHEAT FIELD

The gradient of CO₂ concentration, photosynthetically active radiation(PAR). net radiation.soil heat flux, profiles of wind speed, and air temperature and humidity were measured above a wheat field during May and June 1985 at Beijing Agro-Ecosystems Experimental Station. Beijing,China. Fluxes of carbon dioxide, sensible heat, latent heat and momentum were calculated by using the aerodynamic method. The observation site. equipment, calibration techniques, the errors associated with the measurement, and the computational procedures are described. The results show that the diurnal variations of amplitude of CO₂ concentrations were 103.8 to 27. 0.86. 3 to 22.8 and 69.8 to 11.6 ppm:the average CO₂ concentrations were 331.5. 339.9 and 364.6 ppm for the photosynthesis type, and 369.6. 364.0 and 375.2 ppm for the respiration type at 1. 2 and 10 m above surface, respectively, from May 14 to June 15. In the daytime, transfer direction of the CO₂ fluxes and gradients is from air to crop canopy, and at noon(1100 to 1300 BT(Beijing Time)) the transfer rate reaches negative maximum value. At night, transfer of CO₂ fluxes and gradients is in the reversed direction and reaches positive maximum in the early morning(0400 to 0600 BT). There are strong negative correlations between CO₂ flux and the net radiation(R_n),available energy(H+LE). photosynthetically active radiation(PAR) and momentum flux(τ).     

The morphology of oxygen greenline dayglow emission

In this study, the morphology of the oxygen greenline dayglow emission is presented. The volume emission rate profiles are obtained by using Solomons glow model. The glow model is updated in terms of recent cross sections, reaction rate coefficients and quantum yield of greenline emission. Throughout most of the thermosphere the modelled and observed emission rates are in reasonably good agreement. In the region between 98 and 120 km, the modelled emission rates are substantially higher (about a factor of 1.7) than the observed emission rates. This discrepancy is discussed in terms of scaling of solar fluxes which accounts the variation of solar activity for the day on which calculations are made. The modelled morphology of greenline emission is compared with those cases where WINDII data is available. The modelled and observed morphology is in reasonably good agreement at most of the latitudes above 120 km. In the mesosphere the qualitative nature of morphology is very similar to those of WINDII observation except the modelled emission rates are about a factor of 1.7 higher than the observed emission rates.     

长波辐射时空序列剖面中震兆特征的研究

做出了３２°～４０°Ｎ,８９°～１０５°Ｅ范围内各经纬度结点１９８９年７月～１９９６年１２月长波辐射（ＯＬＲ）月距平值曲线．将各结点的曲线图按经纬度排列起来,构成ＯＬＲ时空序列剖面图．根据对这些剖面图的分析,研究了强震前ＯＬＲ的变化特征．结果表明,强震前１～４个月震中附近结点ＯＬＲ曲线变化出现异常,表现为反向变化或振荡型．有的地震前异常的空间展布呈条带状．     

永安西南5.1级地震前尤溪电磁辐射异常特征的研究

本文通过研究1997年5月31日永安西南M_L=5.1级地震前尤溪电磁辐射异常特征及其与本次地震三要素的关系,探讨利用数字采集仪PP40打印机记录电磁辐射信息,比起模拟记录的优势所在,总结出利用震前电磁辐射异常信息,进行短临地震预报的一些规律。     

Measuring the power spectrum of density fluctuations at intermediate redshift with X-ray background observations

The precision of intensity measurements of the extragalactic X-ray background (XRB) on an angular scale of about a degree is dominated by spatial fluctuations caused by source confusion noise. X-ray source counts at the flux level responsible for these fluctuations, ∼10⁻¹² erg cm⁻² s⁻¹, will soon be accurately measured by new missions, and it will then be possible to detect the weaker fluctuations caused by the clustering of the fainter, more distant sources which produce the bulk of the XRB. We show here that measurements of these excess fluctuations at the level of (Δ I/I )∼2×10⁻³ are within reach, improving by an order of magnitude on present upper limits. Since it is likely that most (if not all) of the XRB will be resolved into sources by AXAF , subsequent optical identification of these sources will reveal the X-ray volume emissivity in the Universe as a function of redshift. With these ingredients, all-sky observations of the XRB can be used to measure the power spectrum (PS) of the density fluctuations in the Universe at comoving wavevectors k _c∼0.01–0.1 Mpc⁻¹ at redshifts where most of the XRB is likely to originate ( z ∼1–2) with a sensitivity similar to, or better than, the predictions from large-scale structure theories. A relatively simple X-ray experiment, carried out by a large-area proportional counter with a 0.5–2 deg² collimated field of view scanning the whole sky a few times, would be able to determine the PS of the density fluctuations near its expected peak in wavevector with an accuracy better than 10 per cent.