Some studies on the solar microwave bursts in relation to the slowly varying component

The occurrences of 5772 microwave bursts recorded by the Sagamore Hill and Manilla Solar Radio Observatories over the period January 1968 to July 1970, covering the maximum phase of the current solar cycle at frequencies 2695, 4995 and 8800 MHz and their energy excesses have been examined in relation to the S-component of solar radio emission. The average slowly varying component has been determined by the superposed epoch method commonly known as the Chree analysis. Similar treatment of the bursts, data, mentioned above has been made to examine any probable 27-day variation and the results obtained have been compared with that of the S-component. Further, spectra of the microwave bursts under the so-called spectral type - inverted U, particularly those having a peak at 4995 MHz, have also been examined and compared with the average spectrum of the S-component. Some of the important results obtained from the present analysis are: (1) the nature of variation of both the average number of occurrences and energy excesses of the microwave bursts follow in general the average 27-day variation of the S-component, (2) the number of occurrences and energy excesses of the microwave bursts are comparatively greater in the ascending phase of the 27-day cycle than those in the descending phase, (3) bursts at progressively higher frequencies originate at lower levels in the solar atmosphere than those of the associated S-component, and (4) the average spectrum of the microwave bursts of inverted U spectral type having a peak at 4995 MHz is quite identical in nature to that of the S-component.     

Diurnal surface temperature difference index derived from ground-based meteorological measurements for assessment of moisture availability

Droughts have become widespread in the Northern Hemisphere, including in China, where they have affected farmland resources on the Loess Plateau. Given this background, we proposed a new index, the Normalized Day-Night Surface Temperature Index (NTDI), to estimate moisture availability (m_a), defined as the ratio of actual to reference evapotranspiration. The NTDI is defined as the ratio of the difference between the maximum daytime surface temperature and the minimum nighttime surface temperature, to the difference between the maximum and minimum surface temperatures estimated from meteorological data by applying energy balance equations.To calculate the index, we used data of 20 clear-sky meteorological observations made during the 2005 growing season at a natural grassland station in the Liudaogou River basin on the Loess Plateau. The NTDI showed a significant inverse exponential correlation with m_a (R² = 0.97, p < 0.001), whereas the numerator of the index (the maximum daytime surface temperature minus the minimum nighttime surface temperature) was only weakly correlated with m_a (R² = 0.24, p = 0.03). This result indicates that normalization relative to the index denominator (maximum surface temperature − minimum surface temperature) dramatically improved the accuracy of the estimate.     

1986年2月初太阳活动区的形态研究

根据Marshall空间飞行中心(MSFC)太阳天文台的矢量磁场测量和云南天文台的黑子细节照相资料,作者们详细研究了1986年2月初太阳大活动区(AR4711)的形态和演化。主要结论如下: i)几乎在活动区中每处地方,相距五小时观测到横向磁场排列方向和黑子半影纤维形态之间存在良好的相似性。 ii)利用文[4]的方法,推断了本活动区强的垂直电流源和强的水平电流渠道。 iii)与1972年8月初著名的太阳活动区(McMath 11976)相类似,沿老活动区的中性线的新浮磁通管的两足点(偶极黑子)的分离运动导致了一个密集四极磁结构的形成。 iv)新浮磁通管似乎是本活动区最强的电流系统。 上述结论将为进一步研究本区电流/磁场环系的演化及其与耀斑活动的关系提供一个基础数据。     

Correlation Between the Sunspot Number,the Total Solar Irradiance,and the Terrestrial Insolation

Our study deals with the correlations between the solar activity on the one hand and the solar irradiance above the Earth’s atmosphere and at ground level on the other. We analyzed the combined ACRIM I+II time series of the total solar irradiance (TSI), the Mauna Loa time series of terrestrial insolation data, and data of terrestrial cosmic ray fluxes. We find that the correlation between the TSI and the sunspot number is strongly non-linear. We interpret this as the net balance between brightening by faculae and darkening by sunspots where faculae dominate at low activity and sunspots dominate at high activity. Such a behavior is hitherto known from stellar analogs of the Sun in a statistical manner. We perform the same analysis for the Mauna Loa data of terrestrial insolation. Here we find that the linear relation between sunspot number and insolation shows more than 1% rise in insolation by sunspot number variations which is much stronger than for the TSI. Our conclusion is that the Earth atmosphere acts as an amplifier between space and ground, and that the amplification is probably controlled by solar activity. We suspect the cosmic rays intensity as the link between solar activity and atmospheric transparency. A Fourier analysis of the time series of insolation shows three dominant peaks: 10.5, 20.4, and 14.0 years. As a matter of fact, the cosmic rays data show the same pattern of significant peaks: 10.7, 22.4, and 14.9 years. This analogy supports our idea that the cosmic rays variation has influence on the transparency of the Earth atmosphere.     

Three-Dimensional (3-D) Reconstructions of EISCAT IPS Velocity Data in the Declining Phase of Solar Cycle 23

The European Incoherent SCATter (EISCAT) radar has been used for remote-sensing observations of interplanetary scintillation (IPS) for a quarter of a century. During the April/May 2007 observing campaign, a large number of observations of IPS using EISCAT took place to give a reasonable spatial and temporal coverage of solar wind velocity structure throughout this time during the declining phase of Solar Cycle 23. Many co-rotating and transient features were observed during this period. Using the University of California, San Diego three-dimensional (3-D) time-dependent computer assisted tomography (C.A.T.) solar-wind reconstruction analysis, we show the velocity structure of the inner heliosphere in three dimensions throughout the time interval of 20 April through 20 May 2007. We also compare to white-light remote-sensing observations of an interplanetary coronal mass ejection (ICME) seen by the STEREO Ahead spacecraft inner Heliospheric Imager on 16 May 2007, as well as to in-situ solar-wind measurements taken with near-Earth spacebourne instrumentation throughout this interval. The reconstructions show clear co-rotating regions during this period, and the time-series extraction at spacecraft locations compares well with measurements made by the STEREO, Wind, and ACE spacecraft. This is the first time such clear structures have been revealed using this 3-D technique with EISCAT IPS data as input.     

Reconstruction of the North–South Solar Asymmetry with a Kuramoto Model

This paper applies a Kuramoto model of coupled oscillators to investigate the north–south (N–S) solar asymmetry and properties of meridional circulation. We focus our study on the asymmetry of the 11-year phase, which is slight but persistent: only two changes of sign (around 1928 and 1968) are observed in the past century. We present a model of two non-linear coupled oscillators that links the hemispheric phase asymmetry of sunspots with the asymmetry of the meridional flow. We use a Kuramoto model with evolving frequencies and constant symmetric coupling to show how asymmetry in meridional circulation could produce a persistent phase lead of one solar hemisphere over the other. We associate the natural frequencies of the two oscillators with the velocities of the meridional flow cells in the northern and southern hemispheres. We assume the respective circulations to be independent and estimate the value of the relevant cross-equatorial coupling by the coupling coefficient in the Kuramoto model. We find that a persistent N–S asymmetry of sunspots and the change of the leading hemisphere could indeed both be the result of the evolving frequencies of meridional circulation; the necessary asymmetry of the meridional flow may be small; and the cross-equatorial coupling has an intermediate range value. Possible applications of these results in solar dynamo models are discussed.     

Further investigations of the fog in the photo-electric condensation nucleus counter

Summary The effect on extinction of isothermal distillation, shrinking of the droplets by evaporation without recondensation of the liberated water vapour, coagulation and differential settling of the fog droplets which take place in the fog of a photo-electric nucleus counter and which can produce a small additional extinction («creep») in the first seconds after its formation, were numerically examined. The relative contribution of each process to the total creep observed is assessed. It is found that isothermal distillation can produce amounts of creep (up to 1.70%) which exceed considerably those caused by evaporation or coagulation. The results of these computations explain the occurrence of creep with concentrations greater than approx. 25 000 nuclei/cm³ in fog-tubes of 3.85 cm air-column diameter.That the disappearance of creep in fog-tubes of diameters 2.5 cm and less is due to the accelerated heat-flow from the walls of the narrow fog-tube was previously proved by reducing appropriately the diameter of the light pencil through the fog. In order to meet the objection that by restricting the cross section of the light pencil the fine structure of the fog comes into play, the increase in the travel time of the heat from the walls was achieved this time by using a photo-electric counter with a fog-tube of 8 cm diameter and a light beam of 2.8 cm diameter as in the «Standard Counter 1946». As expected, creep was found in every single measurement up to readings of 53%. Typical examples of the galvanometer pointer-movement and photographic records of the extinction during fog formation in such a wide fog-tube for readings between approx. 10 and 76% are given and their peculiarities discussed.The extinction over the range from 175 000 to 20 000 nuclei/cm³ was also measured with a red and a blue monochromatic interference filter and the results contrasted against the computed extinctions for these two wave lengths. It was ascertained that for the same number of nuclei the extinction for red light is in general larger than that for blue; the difference between the observed extinctions varies considerably, becoming zero or even negative. The most striking feature, however, is the different course of the extinction for the two wave lengths as a function of the number or size of the droplets.The size of the fog droplets in the counter was deduced from the extinction measurements for these two wave lengths and by collecting the falling droplets on coated slides. The radius of the droplets obtained by the optical method varies from 1.81 to 3.19 when the extinction decreases from 86 to 56%. The radius of the droplets as deduced from gelatine coated slides dyed with Naphtol Green B increases from 1.44 at 67.4% extinction (42 400 nuclei/cm³) to 6.30 at 15.6% (858 nuclei/cm³).

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Zusammenfassung Der Einflus der isothermalen Destillation, des Einschrumpfens der Tröpfchen durch Verdunstung ohne Wiederkondensation des freiwerdenden Wasserdampfes, des Zusammenfliessens und Absetzens der Nebeltröpfchen auf die Extinktion, welche im Nebel des photo-elektrischen Kernzählers stattfinden und die in den ersten Sekunden nach seiner Bildung eine kleine zusätzliche Extinktion (im folgenden Kriechen genannt) erzeugen können, wurde numerisch geprüft. Der entsprechende Beitrag jedes einzelnen der oben genannten Prozesse zum Gesamtbetrag des beobachteten Kriechens wurde abgeschätzt. Es wurde gefunden, dass isothermale Destillation zusätzliche Extinktions-Beträge (bis zu 1.70%) erzeugen kann, welche jene durch Verdunstung oder Zusammenfliessen der Tröpfchen verursachten, beträchtlich übersteigen. Die Resultate dieser Berechnungen erklären das Auftreten des Kriechens bei Konzentrationen grösser als ca. 25 000 Kerne per cm³ in Nebelrohren von 3.85 cm Luftsäulen-Durchmesser.Dass das Verschwinden des Kriechens in Nebelrohren mit einem Durchmesser von 2.5 cm und weniger dem beschleunigten Wärmefluss von den Wänden des engen Nebelrohres zuzuschreiben ist, wurde früher durch eine entsprechende Verengung des Lichtbündels, welches zur Durchleuchtung des Nebels verwendet wird, bewiesen. Um dem Einwand zu begegnen, dass bei so starker Verkleinerung des Querschnittes des Lichtbündels, wie sie benützt wurde, schon die Feinstruktur des Nebels eine Rolle spielt, wurde diesmal die Verlängerung der Laufzeit der Wärme von den Wänden durch Erweiterung des Nebelrohres auf 8 cm Durchmesser erzielt, während der Durchmesser des Lichtbündels mit 2.8 cm — wie im «Standard photo-elektrischen Kernzähler 1946» — unverändert belassen wurde. Entsprechend den Erwartungen wurde bei jeder einzelnen Messung bis zu Lesungen von 53% Kriechen festgestellt. Typische Beispiele der Bewegung des Galvanometer-Zeigers und photographische Aufzeichnungen der Extinktion während der Nebelbildung in einem solchen weiten Nebelrohr werden für Lesungen zsischen ca. 10 und 76% gegeben und ihre Eigentümlichkeiten besprochen.Die Extinktion für Konzentrationen zwischen 175 000 und 20 000 Kernen per cm³ wurde auch mit einem roten und blauen Interferenz-Filter gemessen und die Resultate den für diese zwei Wellenlängen berechneten Extinktionen gegenübergestellt. Es wurde festgestellt, dass bei der gleichen Kernzahl die Extinktion für rotes Licht im allgemeinen grösser ist als jene für blaues; die Differenz zwischen den beobachteten Extinktionen schwankt beträchtlich, wird null oder sogar negativ. Am auffallendsten ist jedoch der verschiedene Verlauf der Extinktion für die zwei Wellenlängen als Funktion der Zahl oder Grösse der Tröpfchen.Die Grösse der Nebeltröpfchen im Nebelrohr des photo-elektrischen Kernzählers wurde aus den Extinktions-Messungen in diesen zwei Wellenlängen und durch Auffangen der fallenden Tröpfchen auf Mikroskop-Objektträgern und Deckgläsern, welche mit gefärbter Gelatine überzogen waren, bestimmt. Der Radius der Tröpfchen, welcher mittels der optischen Methode ermittelt wurde, liegt zwischen 1.81 und 3.19 , wenn die Extinktion von 86 auf 56% abnimmt.Der Tröpfchenradius, wie er aus den Flecken auf den Mikroskopgläschen, deren Gelatineüberzug mit Naphtol Grün B eingefärbt war, bestimmt wurde, wächst von 1.44 bei 67.4% Extinktion (42 400 Kerne per cm³) auf 6.30 bei 15.6% (858 Kerne per cm³).

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The research reported in this article has been sponsored and supported in part by the Geophysics Research Directorate of the Air Force Cambridge Research Center, Air Research and Development Command, United States Air Force, under Contract AF 61(052)-26, through the European Office, ARDC in Brussels.     

The Pleistocene evolution of the East Antarctic Ice Sheet in the Prydz bay region: stable isotopic evidence from ODP Site 1167

Ocean Drilling Program Leg 188, Prydz Bay, East Antarctica is part of a larger initiative to explore the Cenozoic history of the Antarctic Ice Sheet through direct drilling and sampling of the continental margins. In this paper, we present stable isotopic results from Ocean Drilling Program (ODP) Site 1167 located on the Prydz Channel Trough Mouth Fan (TMF), the first Antarctic TMF to be drilled. The foraminifer-based δ¹⁸O record is interpreted along with sedimentary and downhole logging evidence to reconstruct the Quaternary glacial history of Prydz Bay and the adjacent Lambert Glacier Amery Ice Shelf System (LGAISS). We report an electron spin resonance age date of 36.9±3.3 ka at 0.45 m below sea floor and correlate suspected glacial–interglacial cycles with the global isotopic stratigraphy to improve the chronology for Site 1167. The δ¹⁸O record based on planktonic (Neogloboquadrina pachyderma (s.)) and limited benthic results (Globocassidulina crassa), indicates a trend of ice sheet expansion that was interrupted by a period of reduced ice volume and possibly warmer conditions during the early–mid-Pleistocene (0.9–1.38 Ma). An increase in δ¹⁸O values after 900 ka appears to coincide with the mid-Pleistocene climate transition and the expansion of the northern hemisphere ice sheet. The δ¹⁸O record in the upper 50 m of the stratigraphic section indicates as few as three glacial–interglacial cycles, tentatively assigned as marine isotopic stages (MIS) 16–21, are preserved since the Brunhes/Matuyama paleomagnetic reversal (780 ka). This suggests that there is a large unconformity near the top of the section and/or that there may have been few extreme advances of the ice sheet since the mid-Pleistocene climate transition resulting in lowered sedimentation rates on the Prydz Channel TMF. The stable isotopic record from Site 1167 is one of the few available from the area south of the Antarctic Polar Front that has been linked with the global isotopic stratigraphy. Our results suggest the potential for the recovery of useful stable isotopic records in other TMFs.