基于CMIP5模式与Argo观测数据的海洋有效重力势能分析

有效重力势能作为重力势能中活跃的部分,能够参与海洋能量循环。本文计算和评估了CMIP5中9个模式的全球大洋2 000 m以上积分的有效重力势能和200～500 m深度范围内的中尺度有效重力势能,并与由BOA_Argo观测数据计算的结果进行比较。分析表明,就全球大洋2 000 m以上积分的有效重力势能而言,多数模式的计算结果均大于由Argo观测数据计算的结果。通过比较有效重力势能的空间分布特征,发现在强动力活跃区（特别是黑潮、湾流、南极绕极流区）,模式与观测相差较大,其差别主要来源于观测与模式中扰动密度的差异。此外,在黑潮和南大洋区域,涡动能和有效重力势能具有较高的时间相关性,而在北大西洋湾流区域,两者的相关性较低;功率谱分析显示中尺度有效重力势能与涡动能都存在显著的半年和年变化周期。     

Modeling urban growth in a metropolitan area based on bidirectional flows,an improved gravitational field model,and partitioned cellular automata

Simulating urban landscape dynamics in metropolitan areas has attracted much attention lately, but the difficulty remains. Although large-scale urban simulation studies consider spatial interaction as an important factor, spatial interaction cannot be accurately measured based on a single element flow, and its effects may not strictly follow a distance decay function. Furthermore, different cities may require different transition rules. In this study, we combined bidirectional flows of population and information and an improved gravitational field model to model the urban spatial interaction, and we then integrated a partitioned cellular automata (CA) model to simulate the urban growth for different cities in the Yangtze River middle reaches megalopolis. It was found that the simulation results generated by the CA model considering spatial interaction are significantly improved. Furthermore, partitioned conversion thresholds can effectively improve the model performance. The proposed model showed a much better performance in the simulation of subordinate cities surrounding the core cities, than for the core cities and fringe cities. We suggest that large-scale urban simulation should pay more attention to the development of partitioned transition rules. The effects of intercity urban flows should also be considered in the simulation of small- and medium-sized cities near the regional cores.     

矩形棱柱体重力位三阶梯度张量正演计算公式

基于位场理论推导出矩形棱柱体重力位三阶梯度张量正演计算的解析公式,采用理论模型对比解析公式与重力位二阶梯度张量中心差分的计算结果,并以是否满足拉普拉斯方程作为检验标准,对推导公式的正确性进行验证。     

A Brief Review of Kilonova (Mergernova) Researchestwo

The neutron star-neutron star and neutron star-black hole mergers may cause the intense radiation of high-frequency gravitational waves (GWs), they can also produce various electromagnetic emissions by ejecting materials outwards. Therefore, these merger events are the most important targets of current multi-messenger astronomical studies. The thermal transient radiation emitted from merger ejecta is called the kilonova or, more generally, the mergernova, which is powered by the radioactive decays of r-process elements, and the energy injection from the central merger product. This phenomenon was first predicted theoretically by Li and Paczynski in 1998, and confirmed by the optical-infrared observations of the GW170817 event in 2017. As a result, the kilonova/mergernova observation had played a crucial role in locating GW170817, identifying its astrophysical origin, and even constraining the nature of the merger product of this event. This paper briefly reviews the primary progress of kilonova/mergernova researches, including the initiative, improvement, and development of the model, the observational discoveries of candidates, and the optical electromagnetic counterpart of GW170817.     

位Love数与位移Love数之间的函数关系的注释

固体潮Love数是表示引潮力与地球形变之间关系的参数,在地球科学中有重要应用价值。地球在各种力学机制的作用下产生了形变,形变又导致地球引力位的变化,即形变附加位或Euler引力位增量。Grafarend等基于矢量球函数的基本理论,在地球密度球对称情况下,给出了形变地球的Euler引力位增量的表达式,并利用Love-Shida假设,给出了位和位移Love数之间的函数关系。本文重新研究了Grafarend等(1997)的工作,在指出其推导过程中的一处错误后,修正了位和位移Love数的之间的函数关系。     

卫星重力反演的短弧长积分法研究

给出了统一求解球谐位系数、弧段边界轨道改正向量、有偏距离改正及加速度计偏差的短弧长积分法,通过对力模型梯度改正减弱了轨道误差对反演地球重力场的影响.采用GRACE卫星1个月的实测轨道及星间距离数据计算表明,短弧长积分法加了梯度改正的精度比不加梯度改正整体提高了近一倍,且该方法在高阶次位系数的精度优于动力学法.基于GRA...     

基于三角高程测量的跨海高程传递方法

对黄岛试验区实测数据进行最小二乘平差和抗差估计解算,结果表明,对于10km以内的跨海距离,基于三角高程测量的跨海正常高程传递精度为2mm/km,达到二等水准的要求.基于三角高程测量的跨海正常高差与直接观测的水准高差和EGM08模型的计算高差互差均小于3mm/km,与天文重力水准计算的高差互差为5mm/km.     

切变基流中惯性重力波的发展

采用分层浅水波方程、一简单的二层模式和ＷＫＢ方法，考虑基本气流的垂直切变，水平切变以及地形的影响，分析了惯性重力波的发展变化，得到有关导式波和曳式波发展的环境条件。     

Time-delay Interferometry for ASTROD-GW

ASTROD-GW(ASTROD[Astrodynamical Space Test of Relativity using Optical Devices] optimized for Gravitational Wave detection) is an optimization of ASTROD to focus on the detection of gravitational waves. Three spacecraft in the mission are positioned respectively in the vicinity of the Sun- Earth Lagrange points L3, L4 and L5. They form a nearly equilateral interferometerarray with the arm lengths of about 260 million kilometers. A set of optimized 20-yr mission orbits of the ASTROD-GW spacecraft are worked out by us. And with this, we have performed the numerical simulation of time-delay interferometry under the CGC2.7 (CGC: Center for Gravitation and Cosmology) ephemeris framework.