云南天文台高分辨太阳光球CCD图象系统

介绍了配置在云南天文台太阳精细结构望远镜的高分辨光球ＣＣＤ图象系统的总体性能、硬件配置、附加光学系统和软件。给出了它的技术检测和试用结果。最后提出了若干改进和完善的考虑,以及对有关观测和研究方面的一些预期和展望。     

一个太阳微波射电爆发中的快速脉动现象

１９９０年７月３０日观测到一个射电大爆发,其中在２８４０ＭＨｚ射电爆发的峰值附近,发现了周期约为３０ｍｓ的快速脉动现象,脉动是窄带的,调制度约为５０％。     

VIRGO: Experiment for helioseismology and solar irradiance monitoring

The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar constant, two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given.died 13 October 1994     

Long-period geomagnetic pulsations caused by the solar wind negative pressure impulse on 22 March 1979 (CDAW-6)

An analysis is made of the long-period geomagnetic pulsations as recorded at seven Norilsk meridian stations ( = 162°, latitudinal range: 61°–71°N) following abrupt magnetospheric expansion during the storm of 22 March 1979 caused by a rapid decrease in solar wind density. As with the time interval following an abrupt contraction at the time of sudden storm commencement, there exist two types of pulsations in the pulsation spectra: latitude-independent (T>400 s) and latitude-dependent (T<200 s) pulsations. The first pulsation type is interpreted in terms of forced pulsations associated with magnetopause oscillations. The oscillation period is determined by plasma density in the boundary layer and by the radius of the magnetosphere (T ^1/2R⁴). The latitudinal dependence of the period, amplitude and polarization of the second-type pulsations is in agreement with the resonance mechanism of their origin.     

On the periodic variations of geomagnetic activity indices Ap and ap

Yearly averages of geomagnetic activity indices Ap for the years 1967–1984 are compared to the respective averages of v² · B_s, where v is the solar wind velocity and B_s is the southward interplanetary magnetic field (IMF) component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap with v² and B_s separately we find that, during the declining phase of the solar cycle, v² and during the ascending phase B_s have more influence on Ap. According to this observation (using Fourier spectral analysis) the semiannual and 27 days, Ap variations for the years 1932–1993 were analysed separately for years before and after sunspot minima. Only those time-intervals before sunspot minima with a significant 27-day recurrent period of the IMF sector structure and those intervals after sunspot minima with a significant 28–28.5-day recurrent period of the sector structure were used. The averaged spectra of the two Ap data sets clearly show a period of 27 days before and a period of 28–29 days after sunspot minimum. Moreover, the phase of the average semiannual wave of Ap is significantly different for the two groups of data: the Ap variation maximizes near the equinoxes during the declining phase of the sunspot cycle and near the beginning of April and October during the ascending phase of the sunspot cycle, as predicted by the Russell-McPherron (R-M) mechanism. Analysing the daily variation of ap in an analogue manner, the same equinoctial and R-M mechanisms are seen, suggesting that during phases of the solar cycle, when ap depends more on the IMF-B_s component, the R-M mechanism is predominant, whereas during phases when ap increases as v increases the equinoctial mechanism is more likely to be effective.     

从反射太阳光谱反演大气气溶胶体积谱分布的理论研究

由大气顶射出太阳辐射的形式解出发,结合球形粒子的米散射理论,由反射太阳光谱推导获得了反演整层大气气溶胶粒子体积谱分布的权重函数。在权重函数特征分析的基础上,根据一个简单的线性反演算法,利用大气辐射传输计算模拟的大气顶反射太阳光谱,反演获得了不同气溶胶浓度和复折射率条件下的气溶胶粒子体积谱。结果表明,初步建立了一套自洽的大气气溶胶体积谱分布的反演方法。通过米散射计算获得的反演参数考虑了波长对粒子半径的权重特征,使气溶胶体积谱的反演具有了明确的物理依据;同目前常用的查算表方法相比,简化了反演方案中参数化的复杂程度。     

Radiative energy partition and cloud radiative forcing at a Po valley site

Values of downward and upward flux densities of solar and terrestrial radiation were continuously recorded between 1 December 2001 and 30 November 2002 using a four-components radiometer at S. Pietro Capofiume (SPC) in northern Italy (44°39′N, 11°37′E, alt. 11 m a.m.s.l.), which is characterized by a weakly-reflective surface. The aim of the study was to investigate the effects of clouds on surface radiation balance (SRB); the cloud fraction (N) has been retrieved through the inverted form of the parameterization proposed by Kasten and Czeplak [Solar Energy 24 (1980) 177] and cloud types estimated following the methodology of Duchon and O'Malley [J. Appl. Meteorol. 38 (1999) 132]. The cloud radiative forcing (CRF) was evaluated through the Bintanja and Van den Broeke [Int. J. Climatol. 16 (1996) 1281] formula and then associated with cloud type. Experimental results showed that during the measuring period the net shortwave (Sw) balance always decreased with increasing N, whereas the net longwave (Lw) balance increased in all seasons. The net radiation available at the surface decreased with increasing N in all seasons except in winter, where no significant dependency was detected.The analysis of the cloud radiative forcing indicates that all seasons were characterized by a net cooling of the surface except winter, where clouds seem to have no effects on the surface warming or cooling. Taking into account the dependence on solar radiation cycle, an intercomparison between the retrieved cloud types seems to indicate that the effect of stratus was a slight cooling whereas that of cumulus clouds was a stronger cooling of the surface. On the contrary, cirrus clouds seem to have slight warming effect on the surface.The annual trends of mean monthly values of shortwave and longwave radiation balances confirmed that the measurement site is characterized by a temperate climate. Moreover, in spite of the cooling effect of clouds, a monthly radiative energy surplus is available all year long for surface–atmosphere energy exchanges. The analysis is also instrumental for the detection of SRB variations.     

A decadal solar effect in the tropics in July–August

The availability of global gridded precipitation and outgoing long-wave radiation (OLR) data after 1978 makes possible an investigation of the influence of the decadal solar oscillation in the tropics during three solar maxima and two solar minima. The NCEP/NCAR reanalyses starting in the 1950s allows the inclusion of an additional two solar maxima and minima to look for consistency of response across a longer time period. In the northern summer (July–August), the major climatological tropical precipitation maxima are intensified in solar maxima compared to solar minima during the period 1979–2002. The regions of this enhanced climatological precipitation extend from the Indian monsoon to the West Pacific oceanic warm pool and farther eastwards in the Intertropical Convergence Zone of the North Pacific and North American Monsoon, to the tropical Atlantic and greater rainfall over the Sahel and central Africa. The differences between solar maxima and minima in the zonal mean temperature through the depth of the troposphere, OLR, tropospheric vertical motion, and tropopause temperature are consistent with the differences in the rainfall. The upward vertical motion is stronger in regions of enhanced tropical precipitation, tropospheric temperatures are higher, tropopause temperatures are lower, and the OLR is reduced due to higher, colder cloud tops over the areas of deeper convective rainfall in the solar maxima than in the minima. These differences between the extremes of the solar cycle suggest that an increase in solar forcing intensifies the Hadley and Walker circulations, with greater solar forcing resulting in strengthened regional climatological tropical precipitation regimes. These effects are as strong or even more pronounced when warm and cold extremes in the Southern Oscillation are removed from the analyses. Additionally, lower stratospheric temperatures and geopotential heights are higher with greater solar forcing suggesting ozone interactions with solar forcing in the upper stratosphere.     

太阳能在处理水、大气及土壤中有机污染物方面的应用

太阳能除作为传统的热源外，还可用于驱动化学过程。本文主要介绍利用光催化氧化技术处理废水、大气及土壤中有机污染物方面的最新进展，正在进行的现场实验、有关的太阳能设施，目前存在的主要困难及未来的应用前景等。     

夏季北冰洋海冰边缘区海水温盐结构及其形成机理

利用1999年北极科学考察期间在海冰边缘区的三次考察数据，研究了北冰洋海冰边缘区的温度和盐度结构。将海冰边缘区分为机制不同的两大类，一类是暖水海冰边缘区，主要热源是外部暖水进入海冰边缘区携带的热量；另一类是冷水海冰边缘区，主要热源是太阳辐射加热。文中主要对冷水海冰边缘区进行了研究。虽然两个冷水海冰边缘区(R区与T区)温度结构不尽相同，但都存在表层以下水体中的温度极大值现象，R区的温度极大值位于20m左右，T区的位于40—50m左右的深度，可以认为是海冰边缘区的典型温度特征。作者认为，次表层暖水的热源是太阳辐射的直接加热，为此，建立了太阳加热引起海水次表层增暖的物理模型和简单的数学模型，获得了冰下海水在太阳辐射的作用下增暖的解析解。结果表明，部分太阳辐射能穿过海冰加热冰下海水，加热之初温度的极大值出现在近表层，随着时间的推移，海温极大值的位置向下移动，最终可以达到40m左右，证明了仅仅依靠太阳的短波辐射就可以形成中间暖的水层。文中阐明，开阔海水更多的是上混合层和跃层结构，冰下海水主要是次表层暖水结构；冷水海冰边缘区的海水主要带有冰下海水的特征。由于次表层暖水的形成与海冰厚度关系很大，近十几年北冰洋海冰厚度的显著减少势必加强次表层暖水，可能是北冰洋增暖的又一个重要现象，对全球气候变化有意义深远的影响。