Introduction of a New Cycle in Replacement of Metonic: An Ideal Solution towards a Deviation Free Luni-Solar Calendar

Molad is simply an interval between two successive new moon timelines with respect to the line joining the Sun and the Earth i.e., with respect to the Sun as seen from the Earth, which in scientific terms is referred as lunation or “synodic lunar month”. Though synodic lunar month may vary by up to ±0.7 days locally, the length of mean synodic lunar month is constant over a long period of time and is a crucial value in determining the luni-solar calendar’s new months similar to Hebrew calendar’s “Rashei Hodesh”. Based on the Metonic cycle the luni-solar Hebrew calendar adds 07 intercalary months in 19 solar years. This hypothesis proposes a new cycle instead of the Metonic cycle towards eliminating the deviation of the calendar incurred in the long course of time. The research analyzed that application of the conventional Metonic cycle to luni-solar calendar is erroneous, which theoretically leads Hebrew calendar to absorb extra 11 days (approx.) by 2053 years after inception. The study pointed out that through the application of 2116 - 2053 lunar-solar years cycle instead of 235 - 228 lunar-solar months based Metonic cycle, formulation of a far better high precession luni-solar calendar is possible and also both lunar and solar sides of the luni-solar calendar became fully balanced and harmonized.

Regularized luni-solar gravity dynamics on resident space objects

Resident space object population in highly elliptical high perigee altitude(>600 km)orbits is significantly affected by luni-solar gravity.Using regularization,an analytical orbit theory with luni-solar gravity effects as third-body perturbations in terms of Kustaanheimo-Stiefel regular elements is developed.Numerical tests with different cases resulted in good accuracy for both short-and long-term orbit propagations.It is observed that the luni-solar perturbations affect the accuracy of the analytical solution seasonally.The analytical theory is tested with the observed orbital parameters of the few objects in highly elliptical orbits.The analytical evolution of osculating perigee altitude is found to be concurrent with observed data.Solar perturbation,when compared with lunar perturbation,is established to be dominant over such orbits.

基于阴阳历叠加的中长期天气预报方法

采用在阴阳历叠加的基础上进行修正的方法,利用环渤海地区和青藏高原东北部地区1960-2010年地面测站降水、风速资料,探讨了阴阳历叠加法进行中长期天气预报的可行性.结果表明:对于不同地区,不同要素阴阳历叠加预报时最佳样本长度略有差异,降水预报时环渤海地区最佳样本长度为37 a,青藏高原东部地区最佳样本长度为20 a;对大风天气过程而言,环渤海地区最佳样本长度为34 a,青藏高原东北部地区为31 a.降水日预报检验表明,环渤海地区和青藏高原东北部地区降水日预报威胁评分(TS)呈单峰型变化,峰值均集中在夏季,6-8月降水日预报TS评分均高于0.4,两地各月降水日预报TS评分均高于气候概率.利用站点相关订正后,准确率最高可提高14.2%,最低提升了4.1%,平均提高9.8%,站点相关订正是有效的.两地大风预报准确率呈现单峰型分布特征,并在3-5月间为明显的波峰,且两地的预报TS评分均高于气候概率TS评分,预报是有效的.

由PREM模型参数计算地球自转的周期变化

弹性地球在日月引潮力势作用下的形变引起其转动惯量的改变，从而导致地球自转速率的变化．本文利用PREM地球模型所给的物质密度和弹性等参数分布．计算日月引潮力势产生的地球形变附加势，进而计算转动惯量的变化．最后得到一系列包含周期同引潮势带谐项、振幅大于1微秒的自转速率周期变化系数．

国内天文地球动力学中的潮汐研究

简要说明了天文地球动力学范畴内所研究的潮汐现象,包括由日月引潮力引起的固体潮、海洋潮、大气潮和由于地球自转轴的极移引起的极潮,以及这些潮汐对地球自转和地球自转的测量产生的效应。重点阐述中国天文学界在这一领域里的研究成果。这些研究涉及潮汐影响地球自转的机制,也就是各种潮汐效应与极移、自转速率变化和章动的关系,包括构建这类关系的理论模型,分析潮汐对它们的影响,利用中国古代丰富的天象记录计算地球自转的长期减慢,计算弹性或滞弹地球的洛夫数,依据某一地球模型计算潮汐效应或章动序列等等。研究也涉及在测量地球自转参数的不同技术中各种潮汐效应对测量结果产生的影响及其改正,并涉及与潮汐有关的观测方法的优化和数据处理过程的改进。最后介绍了中国学者所发现的脉冲星的周期和周期变率测量中的潮汐效应,尽管它们的量级甚微,但不容忽视。

水准高差的日月潮汐改正

本文研究了日月潮汐对水准高差的影响 ,导出了水准高差的日月潮汐改正公式 ,从而验证了现行水准测量规范引用的公式 ,并发现其存在的个别错误 。

对月日潮汐摩擦耗散的估计

月日潮汐摩擦和地球惯量矩变化是日长长期变化的主要原因.在本文中,利用最新的地球物理和古生物钟数据,对过去15亿年以来的月日潮汐摩擦、地球惯量矩变化和日长长期变化等作了数值对比研究.由此得到二个重要结论:一是仅利用地球的自转形变不能解释J2的变化,这说明地球的重力分异现象至今仍存在着;其二是在几亿年前的潮汐摩擦比现在大得多,若取潮汐耗散与距离的立方成反比时,理论结果与由古生物钟得到的回归年日数和朔望月日数数据较为符合.

彝族文献中的天文历法与二十四节气

彝族天文历法是彝族文化的重要部份。彝族文献中存在大量的天文历法知识,包括二十四节气。通过对彝族史诗和经典著作中的天文历法及二十四节气进行梳理、解读和分析,发现彝族天文历法建立在阴阳宇宙观之上,具有阴阳合历的性质。彝族文献中记载的物候、四季和二十四节气是彝族历法中"阳历"性质的表现。二十四节气是彝汉历法的共同特征。

一个自动确定指针的阴阳历叠加程序

从实际预报出发 ,根据阴阳历之间的关系 ,用 Turbo C语言编写了一个能够灵活、快速自动确定指针的阴阳历叠加程序 。

Analytical long-term evolution and perturbation compensation models for BeiDou MEO satellites

The current paper establishes the analytical models of the long-term evolution and perturbation compensation strategy for Medium Earth Orbits（MEO）shallow-resonant navigation constellation,with application to the Chinese Bei Dou Navigation Satellite System（BDS）.The long-term perturbation model for the relative motion is developed based on the Hamiltonian model,and the long-term evolution law is analyzed.The relationship between the control boundary of the constellation and the offset of the orbital elements is analyzed,and a general analytical method for calculating the offset of the orbit elements is proposed.The analytical model is further improved when the luni-solar perturbations are included.The long-term evolutions of the BDS MEO constellation within 10 years are illustrated,and the effectiveness of the proposed analytical perturbation compensation calculation approach is compared with the traditional numerical results.We found the fundamental reason for the nonlinear variations of the relative longitude of ascending node and the mean argument of latitude is the long-periodic variations of the orbital inclination due to the luni-solar perturbations.The proposed analytical approach can avoid the numerical iterations,and reveal the essential relationship between the orbital element offsets and the secular drifts of the constellation configuration.Moreover,there is no need for maintaining the BDS MEO constellation within 10 years while using the perturbation compensation method.