Numerical study on dry deposition processes in canopy layer

A coupling model between the canopy layer (CL) and atmospheric boundary layer (ABL) for the study of dry deposition velocity is developed. The model consists of six parts: chemical species conservation equation including absorptive factor; the species uptake action including detailed vertical variation of absorptive element in CL; momen-tum exchange in CL which is represented by a first-order closure momentum equation with an additional larger-scale diffusive term; momentum exchange in ABL which is described by a complete set of the ABL turbulent statistic parameters; absorptivity (or solubility or reflection) at the surface including effects of the physical and chemi-cal characters of the species, land type, seasonal and diurnal variations of the meteorological variables; and deposition velocity derived by distributions of the species with height in CL. Variational rules of the concentration and deposi-tion velocity with both height and time are simulated with the model for both corn and forest canopies. Results pre-dicted with the bulk deposition velocity derived in the paper consist well with experimental data.     

Longitudinal heating gradient: Another possible factor influencing the intensity of the Asian summer monsoon circulation

The Largest longitudinal heating gradients in the tropics exist between the African desert and Asian convective regions during summer once the South Asian monsoon is established. The heating gradients are anchored by the la-tent heat release and net radiative flux convergence over the monsoon region, and by the dominant net radiative flux divergence over the desert.An apparent relationship is found between the intensity of the Asian summer monsoon circulation and the longitudinal healing gradients mentioned, in addition to the latitudinal heating gradients cross the monsoon region. The monsoon circulation measured in terms of the zonal wind component is stronger when the longitudinal heating gradients are large, and vice versa. Thus, we claim that the longitudinal heating gradient may be another important factor which influences the intensity of the Asian summer monsoon circulation. There is little evidence that the interannual variability of the longitudinal heating gradients between Africa and Asia and, thus, the intensity of the Asian summer monsoon circulation, is a strong function of the El Nino / Southern Oscillation cycle.     

数值天气预报的进展和展望

本文系统地回顾了近10-15年来中期数值天气预报在数值模拟、资料同化、业务预报技巧、模式系统误差方面的研究进展.着重介绍了欧洲中心ECMWF业务预报模式和资料同化系统的主要变化.最后,对数值天气预报的未来前景作一展望.     

大气动力学的随机性与长期预报问题

一般认为,有三种解决长期天气预报问题的途径:天气学的、统计学的和流体动力学的.事实上,天气学途径正如Б.П.Мулъ-     

EVALUATION OF MODELS FOR ESTIMATION OF NET RADIATION FOR ALPINE SLOPING SURFACES

This paper describes and tests two models for estimating net radiation(or the radiation balance)on sloping surfacesof alpine environments.They are an empirical method based on the linear relationship between net radiation and globalsolar radiation and a flux-by-flux method involving the estimation of all the individual components of radiation budgetindependently.The results show that the empirical method is capable of predicting hourly net radiation on sloping sur-faces to within about±53 W m~(-2) under all sky conditions.During clear sky conditions,it could predict net radiation onslopes to within±58 W m~(-2) or 16% of the measured values.The flux-by-flux method,although it did not perform aswell as the empirical method,performed adequately and could give estimates of net radiation on slopes with root meansquare error of less than 74 W m~(-2)(20%)and a mean bias error of 27 W m~(-2)(7%).     

The Momentum Turbulent Counter-Gradient Transport in Jet-like Flows

Ⅰ. INTRODUCTIONIt is very well known from the observations that some atmospheric motions are accompanied by jets in the boundary layer, for example, breezes and circulations in the mountain valleys (Gutman, 1969); nocturnal increasing of wind (Byzova et al., 1989); cross-equatorial flow during the summer Indian monsoon (Das, 1986) and others. One of the important questions concerning a mathematical modelling of such motions is the problem of the turbulent closure of the equations set which describes the jet dynamics. It is still popular to use for the momentum turbulent flow (u＇w＇) a closure, based within the framework of K-theory on the Boussinesq hypothesis     

印度南部尼伦布尔地区红土风化剖面内金粒的形态及表生金矿床的成因模式

红土风化剖面内的粉状、粗粒状及块状金的出现对矿床成因论提出了新的问题。印度南部尼伦布尔地区表生金矿床中金的形态及结构特征是在风化环境下,由于低温溶液的化学溶解、迁移和再沉淀作用而形成的。剖面上部的金粒为似球形,并有许多蚀斑,而下部的金粒则呈不规则状,且很少被腐蚀。那些外形似海绵状、树技状或丛束状、花瓣状的结构以及在原生颗粒上“涂金”的包壳都表明,它们是次生金初期阶段的产物。根据金粒的赋存状态和外部形态特征,我们总结了一个包括黄铁矿的氧化作用在内的模式,即在酸性环境下,原生矿脉中的金发生溶解,并以氯化物络合物形式移迁。在高Eh值和中等酸碱度条件下,氧化带中的含金络合物就会被分解,以纯金属的形式沉淀下来,并导致金纯度的增加。     

哈萨克斯坦铜—金矿床中金、铋存在的新形式

本文描述了一组新的天然化合物——金铋硫化物,它们产于闪长岩中的少硫化物石英细脉中,属于与毒砂和铁、铜、锌的硫化物共生的Au-Te-Bi系列矿物组合。