Impacts of an Improved Low-Level Cloud Scheme on the Eastern Pacific ITCZ-Cold Tongue Complex

A statistically-based low-level cloud parameterization scheme is introduced, modified, and applied in the Flexible coupled General Circulation Model (FGCM-O). It is found that the low-level cloud scheme makes improved simulations of low-level cloud fractions and net surface shortwave radiation fluxes in the subtropical eastern oceans off western coasts in the model. Accompanying the improvement in the net surface shortwave radiation fluxes, the simulated distribution of SSTs is more reasonably asymmetrical about the equator in the tropical eastern Pacific, which suppresses, to some extent, the development of the double ITCZ in the model. Warm SST biases in the ITCZ north of the equator are more realistically reduced, too. But the equatorial cold tongue is strengthened and extends further westward, which reduces the precipitation rate in the western equatorial Pacific but increases it in the ITCZ north of the equator in the far eastern Pacific. It is demonstrated that the low-level cloud-radiation feedback would enhance the cooperative feedback between the equatorial cold tongue and the ITCZ. Based on surface layer heat budget analyses, it is demonstrated that the reduction of SSTs is attributed to both the thermodynamic cooling process modified by the increase of cloud fractions and the oceanic dynamical cooling processes associated with the strengthened surface wind in the eastern equatorial Pacific, but it is mainly attributed to oceanic dynamical cooling processes associated with the strengthening of surface wind in the central and western equatorial Pacific.

A Statistically-Based Low-Level Cloud Scheme and Its Tentative Application in a General Circulation Model

In this study, a statistical cloud scheme is first introduced and coupledwith a first-order turbulence scheme with second-order turbulence moments parameterized by thetimescale of the turbulence dissipation and the vertical turbulent diffusion coefficient. Then theability of the scheme to simulate cloud fraction at different relative humidity, verticaltemperature profile, and the timescale of the turbulent dissipation is examined by numericalsimulation. It is found that the simulated cloud fraction is sensitive to the parameter used in thestatistical cloud scheme and the timescale of the turbulent dissipation. Based on the analyses, theintroduced statistical cloud scheme is modified. By combining the modified statistical cloud schemewith a boundary layer cumulus scheme, a new statistically-based low-level cloud scheme is proposedand tentatively applied in NCAR (National Center for Atmospheric Research) CCM3 (Community ClimateModel version 3). It is found that the simulation of low-level cloud fraction is markedly improvedand the centers with maximum low-level cloud fractions are well simulated in the cold oceans off thewestern coasts with the statistically-based low-level cloud scheme applied in CCM3. It suggeststhat the new statistically-based low-level cloud scheme has a great potential in the generalcirculation model for improving the low-level cloud parameterization.

The Importance of the Shape Parameter in a Bulk Parameterization Scheme to the Evolution of the Cloud Droplet Spectrum during Condensation

The shape parameter of the Gamma size distribution plays a key role in the evolution of the cloud droplet spectrum in the bulk parameterization schemes. However, due to the inaccurate specification of the shape parameter in the commonly used bulk double-moment schemes, the cloud droplet spectra cannot reasonably be described during the condensation process. Therefore, a newly-developed triple-parameter condensation scheme with the shape parameter diagnosed through the number concentration, cloud water content, and reflectivity factor of cloud droplets can be applied to improve the evolution of the cloud droplet spectrum. The simulation with the new parameterization scheme was compared to those with a high-resolution Lagrangian bin scheme, the double-moment schemes in a parcel model, and the observation in a 1.5D Eulerian model that consists of two cylinders. The new scheme with the shape parameter varying with time and space can accurately simulate the evolution of the cloud droplet spectrum. Furthermore, the volume-mean radius and cloud water content simulated with the new scheme match the Lagrangian analytical solutions well, and the errors are steady, within approximately 0.2%.

A Cloud Detection Scheme for the Chinese Carbon Dioxide Observation Satellite(TANSAT)

Cloud detection is an essential preprocessing step for retrieving carbon dioxide from satellite observations of reflected sunlight. During the pre-launch study of the Chinese Carbon Dioxide Observation Satellite （TANSAT）, a cloud-screening scheme was presented for the Cloud and Aerosol Polarization Imager （CAPI）, which only performs measurements in five channels located in the visible to near-infrared regions of the spectrum. The scheme for CAPI, based on previous cloud- screening algorithms, defines a method to regroup individual threshold tests for each pixel in a scene according to the derived clear confidence level. This scheme is proven to be more effective for sensors with few channels. The work relies upon the radiance data from the Visible and Infrared Radiometer （VIRR） onboard the Chinese FengYun-3A Polar-orbiting Meteoro- logical Satellite （FY-3A）, which uses four wavebands similar to that of CAPI and can serve as a proxy for its measurements. The scheme has been applied to a number of the VIRR scenes over four target areas （desert, snow, ocean, forest） for all seasons. To assess the screening results, comparisons against the cloud-screening product from MODIS are made. The evaluation suggests that the proposed scheme inherits the advantages of schemes described in previous publications and shows improved cloud-screening results. A seasonal analysis reveals that this scheme provides better performance during warmer seasons, except for observations over oceans, where results are much better in colder seasons.

Water Vapor and Cloud Radiative Forcings over the Pacific Ocean Simulated by the LASG/IAP AGCM:Sensitivity to Convection Schemes

Characteristics of the total clear-sky greenhouse effect （GA） and cloud radiative forcings （CRFs）, along with the radiative-related water vapor and cloud properties simulated by the Spectral Atmospheric Model developed by LASGIAP （SAMIL） are evaluated. Impacts of the convection scheme on the simulation of CRFs are discussed by using two AMIP （Atmospheric Model Inter-comparison Project） type simulations employing different convection schemes： the new Zhang-McFarlane （NZH） and Tiedtke （TDK） convection schemes. It shows that both the climatological GA and its response to El Nio warming are simulated well, both in terms of spatial pattern and magnitude. The impact of the convection scheme on GA is not significant. The climatological longwave CRF （LWCRF） and its response to El Nio warming are simulated well, but with a prominently weaker magnitude. The simulation of the climatology （response） of LWCRF in the NZH （TDK） run is slightly more realistic than in the TDK （NZH） simulation, indicating significant impacts of the convection scheme. The shortwave CRF （SWCRF） shows large biases in both spatial pattern and magnitude, and the results from the TDK run are better than those from the NZH run. A spuriously excessive negative climatological SWCRF over the southeastern Pacific and an insufficient response of SWCRF to El Nio warming over the tropical Pacific are seen in the NZH run. These two biases are alleviated in the TDK run, since it produces vigorous convection, which is related to the low threshold for convection to take place. Also, impacts of the convection scheme on the cloud profile are discussed.

Variational Assimilation of Satellite Cloud Water/Ice Path and Microphysics Scheme Sensitivity to the Assimilation of a Rainfall Case

Hydrometeor variables （cloud water and cloud ice mixing ratios） are added into the WRF three-dimensional variational assimilation system as additional control variables to directly analyze hydrometeors by assimilating cloud observations. In addition, the background error covariance matrix of hydrometeors is modeled through a control variable transform, and its characteristics discussed in detail. A suite of experiments using four microphysics schemes （LIN, SBU-YLIN, WDM6 and WSM6） are performed with and without assimilating satellite cloud liquid/ice water path. We find analysis of hydrometeors with cloud assimilation to be significantly improved, and the increment and distribution of hydrometeors are consistent with the characteristics of background error covariance. Diagnostic results suggest that the forecast with cloud assimilation represents a significant improvement, especially the ability to forecast precipitation in the first seven hours. It is also found that the largest improvement occurs in the experiment using the WDM6 scheme, since the assimilated cloud information can sustain for longer in this scheme. The least improvement, meanwhile, appears in the experiment using the SBU-YLIN scheme.

ID-Based User Authentication Scheme for Cloud Computing

In cloud computing environments, user authentication is an important security mechanism because it provides the fundamentals of authentication, authorization, and accounting （AAA）. In 2009, Wang et al. proposed an identity-based （ID-based） authentication scheme to deal with the user login problem for cloud computing. However, Wang et aL＇s scheme is insecure against message alteration and impersonation attacks. Besides, their scheme has large computation costs for cloud users. Therefore, we propose a novel ID-based user authentication scheme to solve the above mentioned problems. The proposed scheme provides anonymity and security for the user who accesses different cloud servers. Compared with the related schemes, the proposed scheme has less computation cost so it is very efficient for cloud computing in practice.

The Impact of Low-Level Cloud over the Eastern Subtropical Pacific on the "Double ITCZ" in LASG FGCM-0

Like many other coupled models, the Flexible coupled General Circulation Model (FGCM-0) suffers from the spurious “Double ITCZ”. In order to understand the “Double ITCZ” in FGCM-0, this study first examines the low-level cloud cover and the bulk stability of the low troposphere over the eastern subtropical Pacific simulated by the National Center for Atmospheric Research (NCAR) Community Climate Model version 3 (CCM3), which is the atmosphere component model of FGCM-0. It is found that the bulk stability of the low troposphere simulated by CCM3 is very consistent with the one derived from the National Center for Environmental Prediction (NCEP) reanalysis, but the simulated low-level cloud cover is much less than that derived from the International Satellite Cloud Climatology Project (ISCCP) D2 data. Based on the regression equations between the low-level cloud cover from the ISCCP data and the bulk stability of the low troposphere derived from the NCEP reanalysis, the parameterization scheme of low-level cloud in CCM3 is modified and used in sensitivity experiments to examine the impact of low-level cloud over the eastern subtropical Pacific on the spurious “Double ITCZ” in FGCM-0. Results show that the modified scheme causes the simulated low-level cloud cover to be improved locally over the cold oceans. Increasing the low-level cloud cover off Peru not only significantly alleviates the SST warm biases in the southeastern tropical Pacific, but also causes the equatorial cold tongue to be strengthened and to extend further west. Increasing the low-level cloud fraction off California effectively reduces the SST warm biases in ITCZ north of the equator. In order to examine the feedback between the SST and low-level cloud cover off Peru, one additional sensitivity experiment is performed in which the SST over the cold ocean off Peru is restored. It shows that decreasing the SST results in similar impacts over the wide regions from the southeastern tropical Pacific northwestwards to the western/central equatorial Pacific as increasing the low-level cloud cover does.

The Cloud Storage Ciphertext Retrieval Scheme Based on ORAM

Due to its characteristics distribution and virtualization, cloud storage also brings new security problems. User＇s data is stored in the cloud, which separated the ownership from management. How to ensure the security of cloud data, how to increase data availability and how to improve user privacy perception are the key issues of cloud storage research, especially when the cloud service provider is not completely trusted. In this paper, a cloud storage ciphertext retrieval scheme based on AES and homomorphic encryption is presented. This ciphertext retrieval scheme will not only conceal the user retrieval information, but also prevent the cloud from obtaining user access pattern such as read-write mode, and access frequency, thereby ensuring the safety of the ciphertext retrieval and user privacy. The results of simulation analysis show that the performance of this ciphertext retrieval scheme requires less overhead than other schemes on the same security level.

Impact of Different Cloud Microphysics Parameterization Schemes on Typhoon Intensity and Structure

The impact of different cloud microphysics parameterization schemes on the intensity and structure of the Super-strong Typhoon Rammasun(1409)in 2014 is investigated using the Weather Research and Forecasting model version 3.4 with eight cloud microphysics parameterization schemes.Results indicate that the uncertainty of cloud microphysics schemes results in typhoon forecast uncertainties,which increase with forecast time.Typhoon forecast uncertainty primarily affects intensity predictions,with significant differences in predicted typhoon intensity using various cloud microphysics schemes.Typhoon forecast uncertainty also affects the predicted typhoon structure.Greater typhoon intensity is accompanied by smaller vortex width,tighter vortex structure,stronger wind in the middle and lower troposphere,greater height of the strong wind region,smaller thickness of the eyewall and the outward extension of the eyewall,and a warmer warm core at upper levels of the eye.The differences among the various cloud microphysics schemes lead to different amounts and distributions of water vapor and hydrometeors in clouds.Different hydrometeors have different vertical distributions.In the radial direction,the maxima for the various hydrometeors forecast by a single cloud microphysics scheme are collocated with each other and with the center of maximum precipitation.When the hydrometeor concentration is high and hydrometeors exist at lower altitudes,more precipitation often occurs.Both the vertical and horizontal winds are the strongest at the location of maximum precipitation.Results also indicate that typhoon intensities forecast by cloud microphysics schemes containing graupel processes are noticeably greater than those forecast by schemes without graupel processes.Among the eight cloud microphysics schemes investigated,typhoon intensity forecasts using the WRF Single-Moment 6-class and Thompson schemes are the most accurate.

LASG Global AGCM with a Two-moment Cloud Microphysics Scheme:Energy Balance and Cloud Radiative Forcing Characteristics

Cloud dominates influence factors of atmospheric radiation, while aerosol–cloud interactions are of vital importance in its spatiotemporal distribution. In this study, a two-moment(mass and number) cloud microphysics scheme, which significantly improved the treatment of the coupled processes of aerosols and clouds, was incorporated into version 1.1 of the IAP/LASG global Finite-volume Atmospheric Model(FAMIL1.1). For illustrative purposes, the characteristics of the energy balance and cloud radiative forcing(CRF) in an AMIP-type simulation with prescribed aerosols were compared with those in observational/reanalysis data. Even within the constraints of the prescribed aerosol mass, the model simulated global mean energy balance at the top of the atmosphere(TOA) and at the Earth’s surface, as well as their seasonal variation, are in good agreement with the observational data. The maximum deviation terms lie in the surface downwelling longwave radiation and surface latent heat flux, which are 3.5 W m-2(1%) and 3 W m-2(3.5%), individually. The spatial correlations of the annual TOA net radiation flux and the net CRF between simulation and observation were around 0.97 and 0.90, respectively. A major weakness is that FAMIL1.1 predicts more liquid water content and less ice water content over most oceans. Detailed comparisons are presented for a number of regions, with a focus on the Asian monsoon region(AMR). The results indicate that FAMIL1.1 well reproduces the summer–winter contrast for both the geographical distribution of the longwave CRF and shortwave CRF over the AMR. Finally, the model bias and possible solutions, as well as further works to develop FAMIL1.1 are discussed.

Evaluation of a Lagrangian advection scheme for cloud droplet diffusion growth with a maritime shallow cumulus cloud case

A Lagrangian advection scheme(LAS)for solving cloud drop diffusion growth was previously proposed(in 2020)and validated with simulations of cloud droplet spectra with a one-and-a-half dimensional(1.5D)cloud bin model for a deep convection case.The simulation results were improved with the new scheme over the original Eulerian scheme.In the present study,the authors simulated rain embryo formation with the LAS for a maritime shallow cumulus cloud case from the RICO(Rain in Cumulus over the Ocean)campaign.The model used to simulate the case was the same 1.5D cloud bin model coupled with the LAS.Comparing the model simulation results with aircraft observation data,the authors conclude that both the general microphysical properties and the detailed cloud droplet spectra are well captured.The LAS is robust and reliable for the simulation of rain embryo formation.

基于云模型的水光互补清洁能源基地容量配置方案优选

为优选水光互补清洁能源基地容量配置方案,从安全性、环保性、经济性、技术性4个方面选取14个指标构建了综合评价指标体系,采用改进云模型方法对容量配置方案进行评价。改进云模型方法以基于层次分析法改进的云模型求解主观权重,以熵权法求解客观权重,组合赋权得到指标权重,再利用条件云发生器计算各指标的隶属度,最后根据级别特征值法计算容量方案等级评分,确定最优方案。将该方法应用于我国西南某清洁能源基地水光互补系统容量配置方案的优选,优选结果与集对分析法优选结果和实际选择方案均相符,证明了该方法的有效性与适用性。

Study on New Generation Spaceborne Rain and Cloud Measuring Radar System Techniques

Dual-frequency and multi-polarization spaceborne rain and cloud measuring radar is the inevitable trend of remote sensing techniques.Techniques of new generation dual-frequency and multi-polarization spaceborne rain and cloud measuring radar are studied systematically.Radar block diagram and main parameters are presented.Antenna subsystem scheme is analyzed and antenna parameters are proposed.Central electronic device subsystem scheme is given and data rate of spaceborne radar is calculated.This paper is a meaningful try for carrying out spaceborne rain and cloud measuring radar design,acting as a reference to Chinese spaceborne rain and cloud measuring radar design and production in future.

基于云模型的高速铁路引入铁路枢纽线路方案优选研究

针对高速铁路引入铁路枢纽线路方案设计所面临的多维环境影响、多重约束条件以及多元评价目标,建立科学的线路方案决策模型成为亟需解决的关键难题。以走得通、走得稳、走得好、走得省为目标,从5个维度选取30项指标建立高速铁路引入铁路枢纽线路方案优选的层次指标体系。采用改进的黄金分割法和云模型理论对定性指标进行系统量化后转化为灰色关联系数矩阵,度量决策信息的差异性和不确定性的同时还能衡量与目标序列趋势变化的趋同程度。为了提供科学客观和准确系统的决策支持,统筹VIKOR法和改进密切值法建立基于客观数据驱动的线路方案决策模型,从不同维度对备选方案进行全面评估;在深入分析沿线5个利益群体的利益诉求以及不利后果的基础上,引入Pythagorean模糊云模型理论优化了由于利益群体有限理性行为所引起的缺陷,并融合逼近理想解排序的思想建立了基于方案偏好驱动的线路方案决策模型,提高方案的可行性和可接受性。最后统筹考虑客观数据信息值以及方案偏好信息值进行综合决策,并结合工程实例对模型进行应用分析。结果表明:基于本模型的决策结果与工程实际具有较好的一致性,验证了模型的可靠性和适用性,为高速铁路引入铁路枢纽线路方案优化设计提供了一定的理论支持。

基于粒子群和改进蚁群算法的云计算任务调度

针对目前云计算任务调度方法的效率较低和日益多样化的用户服务质量需求等问题,提出一种将粒子群算法和改进蚁群算法结合的混合粒子群蚁群算法(HPSO-ACO),包括建立云计算任务调度模型、用户服务质量模型及虚拟资源节点模型。利用离散型粒子群算法,得到初始解集,转化为蚁群算法信息素的初始值,通过改进蚁群算法的寻径规则和信息素更新规则,得到最终解。通过仿真实验将粒子群算法、蚁群算法和HPSO-ACO算法进行比较,其结果表明,HPSO-ACO算法有效且可行,能够减少任务完成时间和降低完成成本,满足用户服务质量要求。

智慧城轨云脑平台总体方案设计

随着大数据、物联网、人工智能、5G等现代信息技术的进步,城市轨道交通逐步朝着智慧化、智能化的方向发展。城市轨道交通系统在运营中会产生大量数据,为促进数据的汇聚、融合和共享应用,需构建作为智慧城轨发展基础平台与数字底座的智慧城轨云脑平台。文章在分析建设智慧城轨云脑平台必要性的基础上,确定智慧城轨云脑平台总体方案设计思路,并以此为基础进行平台总体架构和功能设计,最后对平台在车站、线路、线网3个层面的业务应用进行阐述,以期提升数据治理能力,实现快速流畅的数据交互、全面真实的数据分析、科学精准的决策施策,为城市轨道交通系统的安全、绿色、高效运行提供有力支撑。

10kV智能干式变压器设计浅析

针对10kV干式变压器运维智能化较低的现状,本文作者将传感器和变压器融合设计,形成三种差异化智能配置方案,实现变压器的运行状态和运行环境信息采集。使用基于拉依达准则的野点剔除和基于滑动窗的平局值滤波对绕组温度和铁心温度信号进行预处理,以消除传感器的随机误差和粗大误差,在变压器或运行环境异常时发出告警信号和联动控制信号,并能实现剩余寿命的预测,最后通过云平台实现干式变压器的集中统一管理,提高运维效率和故障响应速度。

新一代基于云架构信号系统建设方案

[目的]以推进城市轨道交通信息化、发展智能系统、建设“智慧城轨”为主题,构建高度集成的城市轨道交通云平台是新时代技术发展方向,信号系统与云平台融合属于信号系统的一个重要发展趋势,需对如何构建高效、可靠、经济的基于云架构的信号系统进行深入研究。[方法]结合常州地铁新一轮城市轨道交通建设方案的需求,根据现有云平台技术特点和信号系统技术现状,对信号系统云化可行性及建设方案进行分析、论证;重点研究线网统一的ATS(列车自动监控)建设方案、信号系统云化范围、云平台架构的选择、云化后信号系统ATS互联互通方案等内容。[结果及结论]明确了信号系统云化的定义,论证了信号系统ATS云化的可行性;根据信号系统云化后能否通过SIL2(安全、完整性等级2)评估,确定了ATS云化的具体设备清单;提出了新一代基于云架构的信号系统建设方案,建议承载ATS的城市轨道交通云平台架构可逐步从模式一向模式三过渡,并应具备更新迭代的能力。信号系统设备融入云平台后能够提升信号系统的处理能力,减少硬件设备数量,并有利于实现线网资源信息互通,促进调度智能化的发展。

基于组合赋权-二维云模型的铁路线路方案优选研究

针对线路方案比选时评价指标体系单一赋权方法的局限性,以及决策过程中多从工程建设结果单方面考虑的问题,提出基于组合赋权-二维云模型的线路方案评价方法。依托沈白铁路通化段线路方案比选实例,以技术可行和生态平衡为导向,选取线路设计、自然人文景观破坏、水土资源环境污染、施工难度及安全4个方面的17个影响线路走向因素,构建线路方案评价指标体系,后运用改进层次分析法与熵权法组合赋权确定指标权重,并以工程建设结果与工后恢复成本作为二维云的2组基础变量,运用MATLAB正向云发生器输出评价云图,确定不同线路方案的隶属等级。结果表明:经新宾、通港方案隶属评价等级介于良好和优秀之间,更贴近良好(Ⅱ级);经新宾、通化县西和经桓仁北、通化县西方案,隶属评价等级介于一般和良好之间,更贴近一般(Ⅲ级);推荐经新宾、通港方案为铁路建设方案,与工程实际选择一致。