A parameterization of the diffuse transmittance and reflectance for aerosol remote sensing problems

To account for surface reflection is a major and most complex issue of any satellite aerosol retrieval algorithm. The surface contribution to the satellite signal is usually calculated assuming Lambertian reflection. Then the problem is reduced to the calculation of total atmospheric transmittance and spherical albedo. Usually, these parameters are stored in so-called look-up tables (LUTs), which can be quite large. The main aim of this paper is the parameterization of these look-up tables in terms of simple approximate equations, which can be subsequently used in aerosol remote sensing techniques over reflecting land surfaces.     

电气系统中电涌保护器的雷电流能量配合设计

分析了电涌保护器(SPD)使用中所涉及到的雷电流能量配合设计。首先分析了单级SPD与被保护设备之间的配合,使用最大振荡距离和耦合距离的计算公式来测算配合的成功性;其次分析了多级SPD之间的配合,着重分析了两级SPD(开关型和限压型组合)的配合,并采用瞬态级间电压降微分方程作为能量配合中所必须遵循的关系式,以及用不同雷电流波形来计算解耦合器的大小,最后提出一个可行的SPD能量配合设计基本步骤。     

Uncertainty in Predicting the Effect of Climatic Change on the Carbon Cycling of Canadian Peatlands

Northern peatlands play an important role globally in the cycling of C, through the exchange of CO2 with the atmosphere, the emission of CH4, the production and export of dissolved organic carbon (DOC) and the storage of C. Under 2 × CO2 GCM scenarios, most Canadian peatlands will be exposed to increases in mean annual temperature ranging between 2 and 6° C and increases in mean annual precipitation of 0 to 15 %, with the most pronounced changes occurring during the winter. The increase in CO2 uptake by plants, through warmer temperatures and elevated atmospheric CO2, is likely to be offset by increased soil respiration rates in response to warmer soils and lowered water tables. CH4 emissions are likely to decrease in most peatlands because of lowered water tables, except where the peat surface adjusts to fluctuating water tables, and in permafrost, where the collapse of dry plateau and palsa will lead to increase CH4 emission. There likely will be little change in DOC production, but DOC export to water bodies will decrease as runoff decreases. The storage of C in peatlands is sensitive to all C cycle components and is difficult to predict. The challenge is to develop quantitative models capable of making these predictions for different peatlands. We present some qualitative responses, with levels of uncertainty. There will be, however, as much variation in response to climatic change within a peatland as there will be among peatland regions.     

A finite–mode model of ideal fluid dynamics on the 2–sphere

We develop the finite-mode model for a two-dimensional Euler system on the sphere based on Hopped’s discovery in group theory. This model strives to keep as many invariants of the original Euler equation as possible. Theoretically, the number of invariants in this model is limited only by computing power. At present, almost all the popular numerical models in weather and climate researches such as numerical weather prediction models and general circulation models (GCMs) use spectral method. However all these spectrally truncated models do not keep all the invariants except for the energy and the enstrophy. By using this model one is able to study the influence from some other lost invariants. The result from this model is expected to be closer to that of the original Euler equations than from ordinary spectrally truncated models. The relevant fundamental equations and important formulas for this model are given explicitly.     

Tabulation of Mie properties for an effective microwave radiative model

Summary In microwave radiative transfer model simulations of atmospheric convective systems, the Mie calculations usually consume the majority of the computer time necessary for the calculations (70 to 90% for frequencies ranging from 6 to 300 GHz). For a large array of atmospheric profiles, the repeated Mie scattering calculations make the radiative transfer modeling not only expensive, but often impossible. A set of Mie tables, therefore, is developed to replace the actual Mie calculations in the microwave radiation model.The tables are divided into categories of liquid water (cloud water and rain), ice, snow, graupel and hail. The tables are free from restriction on variation of size distribution, particle density and mixing phases. Results from this study show that by using the Mie tables, the total CPU time is reduced by at least one order of magnitude, depending on the frequency. Compared to using full Mie calculation in the radiative model, the bias and root-mean-square (rms) deviation from the Mie tables are less than 1.2 K for any atmosphere with precipitation rates up to 125 mm hr^–1 at any frequency and any viewing angle.The Mie tables are particularly useful in simulating the microwave radiation field over a mesoscale meteorological system. Such a study would not be satisfactory using a Mie parameterization scheme, because one would have to trade off the accuracy and flexibility for modeling efficiency.With 7 FiguresThis research was done under contract at the Goddard Space Flight Center, Greenbelt, Maryland.     

THE NONDISPERSION SOLUTION OF NONLINEAR SPIRAL PLANETARY WAVES

In this paper,by using the simplified hydrodynamic equations of barotropic nondivergent atmosphere incylindrial coordinates,the nondispersion cnoidal wave solution of spiral planetary waves is discovered.The formulas of wave speed and the diagnostic relationships between wave parameters are obtained,mostof which are consistent with observed facts.It might mean that the nondispersion cnoidal wave does existin the real atmosphere.At least it might be a first approximation to the actual nonlinear wave.     

BCCAGCM模式在神威·太湖之光系统的优化

开展气象数值模式在神威·太湖之光系统的移植与优化,对研究模式与新型计算架构的适应性有重要意义。该文以BCCAGCM模式为研究对象,将其移植到神威·太湖之光全国产异构众核计算系统,进行性能分析,对模式动力框架和物理过程计算结构进行调整,将计算核心段采用OpenACC技术进行众核加速优化,大量代码进行算法重构。结果表明:各核心段计算效率基本达到未优化的3倍左右,最高可达14倍左右,将各核心段集成,形成异构众核集成版本,可正确、稳定运行,计算误差合理。在不同并行规模,采用从核对模式整体计算进行加速效果比较稳定,基本保持在1.9倍,26000核并行规模动力试验并行效率约70%,其他试验约为57%。     

从云计算到雾计算的范式转变

虽然云计算的应用越来越广泛,但也具有不能支持高移动性、不支持地理位置信息及高时延等亟待解决的问题.为此,雾计算已经出现,并将云计算扩展到网络的边缘,以减少延迟和网络拥塞.首先介绍了雾计算的概念、特点和结构,然后讨论了具有代表性的应用场景以及雾计算的安全问题.另外,还对雾计算相似的原位计算和连续计算进行了介绍.最后,给出了云计算与雾计算的区别与联系,并分析了雾计算未来的发展方向.雾计算扩大了以云计算为特征的网络计算范式,将网络计算从网络的中心扩展到网络的边缘,从而可以更加广泛地运用于更多的应用形态和服务类型.     

饱和水汽压计算公式的分析比较及经验公式的改进

分析比较计算饱和水汽压的Wexler、Goff-Gratch和Magnus等经验公式与实测值的误差。给出拟合Wexler和Goff-Gratch公式计算值的精度较高又便于使用的经验公式。