Variations in exospheric density at heights near 1100km, derived from satellite orbits

In an earlier paper, values of exospheric density were obtained from the orbit of Echo 2 for the years 1964–1965. The results indicated a semi-annual variation in density by a factor of between 2 and 3, considerably larger than predicted by existing atmospheric models.

These studies have now been extended to the beginning of 1967, using both Echo 2 and Calsphere 1, to show how the density is responding to increasing solar activity. Variations in density during 1964 have been analysed in more detail. The long-term variation associated with the solar cycle and the short-term variations associated with magnetic and solar disturbances agree with the variations expected on the basis of current models. The semi-annual variation is persisting to higher levels of solar activity, and although its amplitude is diminishing the factor of variation was still 1.6 in 1966.     

Measurements of radio noise at 0.700 mc and 2.200 mc from a high-altitude rocket probe

Radio noise observations at frequencies of 0·700 Mc and 2·200 Mc were made at altitudes between 3000 and 11,000 km from a Blue Scout Jr. high-altitude rocket probe on 30 July 1963. A steady background flux of (7·5₋₃⁺⁶) × 10⁻¹⁹ W m⁻²)(c/s)⁻¹ at 0·700 Mc and (1·8^+1.0_−0.5 × 10⁻¹⁹ W m⁻² (c/s)⁻¹ at 2·200 Mc was observed. Assuming a galactic origin of the observed fluxes at both frequencies, the averaged sky brightnesses are b(0·700 Mc) = (6₋₃⁺⁵) × 10⁻²⁰ W m⁻² (c/s)⁻¹ sr⁻¹b(2·200 Mc) = (1.4^+1.0_−0.5 × 10⁻²⁰ W m⁻² (c/s)⁻¹ sr⁻¹ The observed brightness at 2·200 Mc is in reasonable agreement with the results of other observers. The apparent brightness at 0·700 Mc is, however, greater than was expected from previous observations. An alternative source of the 0·700 Mc flux in the terrestrial exosphere, as well as characteristics of several noise bursts observed during the flight, is briefly discussed.     

Ionospheric conditions

A general analysis of ionospheric conditions has been made in the light of possible ionic reactions occurring in the upper atmosphere. Data obtained on various parameters, such as ionic production and recombination, show that precise knowledge of the spectral distribution of solar radiation is needed and that other experimental determinations on dissociative recombinations are required.

The ionic complexity of the ionosphere is underlined by describing how the atomic ions O⁺ and N⁺ react with N₂, O₂ and NO molecules. The behavior of the molecular ions N⁺₂, O⁺₂and NO⁺depends on a group of simultaneous processes involving charge transfers and ionatom interchanges which are more important than dissociative recombinations. The altitude distribution of ions is exemplified by discussing the relative importance of various loss coefficients in the D-, E- and F-regions. It is seen that molecular nitrogen ions are subject to important charge transfer processes, that nitric oxide ions are always final products destroyed only by dissociative recombination. Additionally, the entire production of atomic oxygen ions is related to the photoionization of molecular nitrogen. Some information is also given on possible anomalies in the ratio of O⁺₂ and NO⁺ densities in the lower ionosphere. From the lack of sufficient experimental information on ionic processes it is shown that a precise analysis of ionospheric behavior remains highly speculative.     

Equivalent thickness of the outer ionosphere obtained by evaluation of Faraday records

With an appropriate system of higher order approximations the Faraday-effect is calculated for instantaneous ionospheric models the data of which are derived from the results of vertical soundings. Only one parameter which corresponds to the thickness of the outer ionosphere is left open; it is determined by global comparison with simultaneous Faraday-observations of satellite emissions. The thickness parameter shows various forms of variation with latitude; an increase towards north is the rule for quiet daytime conditions. Comparison with local methods shows considerable differences due to the indetermination of the absolute number of rotations.     

中国辽宁-浙江沿海地区川蔓草分布现状、生态特征及其主要威胁

川蔓草(Ruppia)是一种广泛分布在咸水、半咸水生境中的广义海草, 其形成的川蔓草床具有重要的生态学价值。然而, 对于其在中国境内的分布情况尚缺乏大范围的调查。基于此, 本研究于2016—2019年对中国辽宁-浙江沿海区域的川蔓草分布情况进行了初步调查, 探究了调查区域内川蔓草的生境分布类型, 及生态特征, 分析了川蔓草床的主要威胁, 并提出了对川蔓草床科学管理的建议。结果表明: 川蔓草在中国浙江省、江苏省、山东省、天津市、河北省、辽宁省均有分布; 分布面积超过2 100 ha; 该区域内分布的川蔓草物种均为中国川蔓草, 主要分布生境包括咸水养殖池塘、咸水沟渠(池塘)、盐场、瀉湖(湖泊)、潮间带(围堰)5类; 人类活动影响(人工清捞、施药、河道工程等)与极端气候事件(极端干旱事件)都会导致川蔓草床退化, 但大部分川蔓草床可以依靠沉积物中的种子库在环境适宜时进行种群恢复; 不同生境中的川蔓草种群特征差异较大, 因此, 对不同生境中的川蔓草应制定差异性管理措施。     

A combined numerical tidal model for the Hangzhou Bay and Qiantang River

-In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected to the 2-D model for the Hangzhou Bay. The harmonic constants of diurnal constituent [ (K1 O1)/2],semidiurnal constituent (M2) and shallow water constituent (M4) are obtained. The results produced by the combined model are in better agreement with the observed ones than those produced solely by the original 2-D model. The combined model gives much more reliable results for tide-induced residual water level and current.     

斜向波对直立式防波堤堤头作用的试验研究

直立式防波堤堤头在斜向波浪作用下波浪力的计算在现行的技术规范中尚属空白。通过物理模型试验给出了堤头结构设计所需的波压分布图，指出了波浪入射方向和地形对堤头所受波浪力的贡献有时可以超过波高和波周期，根据现行规范按波浪正向入射计算堤头所受的波浪力偏于安全。