Radial velocities of the components of multiple star systems of Trapezium type. I

Translated fromAstrofizika, Vol. 36, No. 2, pp. 273–275, April–June 1993.     

Relative deformations of selenodetic nets of coordinates

One of the main problems of selenodesy consists of the construction of a net of basic reference points on the surface of the Moon. At present there exist many catalogues containing the coordinates of selected objects on the Moon. These catalogues differ by the presence of both systematic and accidental errors.The investigations concerning the comparison of catalogues and the elucidation of their systematic differences are of very recent date. Various methods of interpretation of the systematic differences between catalogues have been proposed. Without an attempt to encompass the whole problem in what follows, we shall describe one method for comparative study of catalogues based on the theory of the deformation of continuous media.     

N–S Asymmetry in the Solar Differential Rotation During 1957–1993

The properties of the differential rotation of the Sun are investigated by using H filaments as tracers. Annual average angular velocities of 716 quiescent filaments are determined from H photoheliograms of the Abastumani Astrophysical Observatory film collection for the years 1957–1993. The existence of north-south (N–S) asymmetry in H filaments rotation is confirmed statistically. The connection of asymmetry with the solar activity cycles is established. It is found that the northern hemisphere rotates faster during the even cycles (20 and 22) while the rotation of southern hemisphere dominates in odd ones (cycles 19 and 21). The mechanism of the solar activity should be responsible for the N–S asymmetry of the solar differential rotation. A theoretical explanation for the N–S asymmetry in the Suns rotation is offered. It is suggested that the asymmetry in the rotation of the two hemispheres of the Sun is balanced by the dynamo mechanism, which acts in parallel to the mechanism offered here. It is concluded that the N–S asymmetry of the solar rotation should cause a difference in activity level between the northern and southern hemispheres.     

Independent selenocentric system of coordinates by large-scale star-calibrated lunar photography

The selenocentric coordinates of 263 craters and one mountain are given. The scale and orientation of the selenocentric coordinates system is determined by star-calibrated lunar photographs obtained with the long-focus horizontal telescope. The origin of the system is defined by the theory of the motion of the Moon. The physical libration is taken into account for the reduction of the coordinates system to the principal axes of the lunar inertia. The reference stars coordinates are reduced to the FK4 system. The position of the lunar mass centre is determined by LURE-2 theory, the rotation parameters are taken from the Migus tables (Migus, 1980).     

Two metamorphic stages in the Svecofennian domain: Evidence from the isotopic geochronological study of the Ladoga and Sulkava metamorphic complexes

The Ladoga, Russia, and adjacent Sulkava, southeastern Finland, metamorphic complexes are the two largest “granulite” provinces of the Svecofennian domain. In this area, the domain is composed of outer and inner zones. Sulkava is situated in the inner zone, which principally can be compared to the accretionary arc complex of Southern Finland. Ladoga is situated in the outer zone, which is correlated with the accretionary arc complexes of central and Western Finland. The complexes contain different metamorphic assemblages, which are caused by the different composition of the sedimentary protoliths: the rocks of the Sulkava metamorphic complex are higher in Al and K than those of the Ladoga Complex. Pb-Pb step leaching dating was used to determine the age of prograde sillimanite from both complexes. The dates thus obtained constrain metamorphic peaks for the Sulkava and Ladoga complexes at 1799 ± 19 Ma and 1878 ± 7 Ma, respectively, which is consistent with the U-Pb monazite ages of gneisses from both of the complexes. The differences in the ages of the metamorphic minerals from these complexes reflect the Early Svecofennian (1.89–1.86 Ga) and Late Svecofennian (1.83–1.79 Ga) metamorphic stages in the Fennoscandian Svecofennides.     

冬、夏季热带及副热带穿透性对流气候特征分析

文中利用热带测雨卫星 (TRMM) 搭载的测雨雷达 (PR) 1998~2007年的探测结果, 就热带及副热带地区穿透性对流的频次、条件降水强度及垂直廓线等特征进行了分析。研究结果表明: 深对流和穿透性对流都主要发生在热带辐合带 ( ITCZ)、南太平洋辐合带 (SPCZ)、亚洲季风区、20°N以南的非洲以及美洲等地区, 它们的空间分布具有明显的地域性和季节变化特征, 而且陆地深对流更容易发展成为穿透性对流, 但绝大部分地区的穿透性对流频次不超过0.2%。对穿透性对流条件降水强度的分析表明, 热带及副热带大部分地区的穿透性对流条件降水强度在10 mm/h以上, 且洋面的条件降水强度要比陆地大, 但由于其频次较小导致其对总降水的贡献并不大。尽管深对流和穿透性对流降水廓线的外形比较相似, 但相同的高度, 深对流的降水强度要比穿透性对流偏小, 而且这种差异随海陆和纬度的不同而有所区别。此外, 热带地区 (15°S~15°N) 冬、夏季深对流和穿透性对流降水廓线都只存在较小差异, 并没有显示出明显的季节变化。     

Dangerous fogs on the territory of Georgia

The statistical structure of dangerous fogs with the visibility of less than 50 m is studied using the observation data of 50 meteorological stations in Georgia for the period of 1961–2006. The contribution of dangerous fogs to the total number of foggy days is estimated. The number of days with dangerous fogs and their duration in different regions of the country are determined and the empirical functions of their distribution, sizes of areas of their expansion, temperature regime, and peculiarities of annual variations are studied.     

中国南方地基雨量计观测与星载测雨雷达探测降水的比较分析

利用热带测雨卫星(TRMM)上搭载的测雨雷达(PR)探测结果和中国40°N以南地区约430个台站雨量计观测结果,分析研究了1998-2005年中国南方地区这两种降水资料气候分布的异同.研究结果表明两种降水资料在2.5°空间水平分辨率上,所描述的中国南方降水率气候分布在多年年平均和季平均上具有较好的一致性,但在降水率极值和极值区范围大小等细节上两者还存在一定的差异,主要是地面雨量计结果相对PR结果偏高,其中中同南方50%以上地区两者相差在1 mm/d以内、30%的地区两者相差在1-2 mm/d,夏季差异可超过2 mm/d.对两种降水资料差异的原因分析表明,地面雨量计空间分布密度是影响两者差异的决定性因素,当格子内雨量计超过6个时,两者的相关系数大于0.7;夏季两种降水资料的相关性都比其他季节差,不论格子内的雨量计数量多与少;对流降水多发地区,两种降水资料之间的差异大于层云降水多发地.利用PR探测结果对夏季青藏高原多年月平均降水率分布及高原东、西部的降水特点的分析表明,6月高原东部出现2 mm/d左右的降水区,而在7和8月1 mm/d的降水区域基本覆盖了除高原西部以外的整个高原,其中高原中部地区出现降水率近3mm/d的大值区.月降水距平的时间演变表明,高原降水偏少月份要多于偏多月份.