Wavelet analysis of turbulence in cirrus clouds

Two flights of the UK Meteorological Offices Hercules aircraft through daytime frontal cirrus around Scotland have been analysed using wavelet analysis on the vertical velocity time-series from the horizontal runs. It is shown that wavelet analysis is a useful tool for analysing the turbulence data in cirrus clouds. It finds the largest scales involved in producing turbulence, as does Fourier analysis, such as the 2-km spectral peaks corresponding to convective activity during flight A283. Wavelet spectra have the added advantage that the position is shown, and so they identify smaller-scale, highly localised processes such as the production of turbulent kinetic energy by the breaking of Kelvin-Helmholtz waves due to the vertical shear in the horizontal wind. These may be lost in Fourier spectra obtained for long time-series, though they contribute something to the average spectral density at the appropriate scale. The main disadvantage of this technique is that only octave frequency bands are resolved.     

Elemental composition of individual chondrules from carbonaceous chondrites,including Allende

Major and trace element analyses of over 180 individual chondrules from 12 carbonaceous chondrites are reported, including individual analyses of 60 chondrules from Pueblito de Allende. Siderophile elements in most chondrules are depleted, compared to the whole chondrite. Correlations of Al-Ir and Ir-Sc among chondrules high in Ca and Al were observed. A Cu-Mn correlation was also found for chondrules from some meteorites. No correlation was observed between Au and other siderophile elements (Fe, Ni, Co and Ir). It is suggested that these elemental associations were present in the material from which the chondrules formed. Compositionally, chondrules appear to be a multicomponent mixture of remelted dust. One component displaying an Al-Ir correlation is identified as Allende-type white aggregates. The other components are a material chemically similar to the present matrix and sulfides-plus-metal material. Abundances of the REE (rare earth elements) were measured in ‘ordinary’ Allende chondrules and were 50% higher than REE abundances in Mokoia chondrules; REE abundances in Ca-Al rich chondrules were similar to REE abundances in Ca-rich white aggregates.     

Theory of decametric radio emissions from Jupiter

It is suggested that the Jovian decametric emissions (DAM) originate in a cyclotron instability of weakly relativistic electrons trapped in the Jovian magnetic field. The resulting radiation has a group velocity in the magnetosphheric plasma which may be of order 10²km/sec, and thus takes much more time to escape the magnetosphere than if the group velocity were at or near the speed of light. Therefore, the asymmetry of the Io phase with respect to sources east and west of the Earth-Jupiter line does not imply an asymmetric beaming of DAM; it is caused by the delay the waves experience in traversing the magnetosphere. The frequency drifts of milli- and decasecond bursts are also explained. It is found that the rotation of the magnetosphere can play an important role, since the observer views the propagation velocity of the waves as the sum of their group velocity and the velocity of the medium itself. The rotation velocity is in opposite directions, relative to the observer, for sources east and west of the Earth-Jupiter line; the resultant vector addition gives positive frequency drifts for decasecond bursts from the early and fourth sources, and negative drifts for bursts from the main and third sources. The negative drifts of millisecond bursts may be the result of large density gradients of plasma in a temporarily compressed magnetosphere.     

Mars: Evidence for dynamic processes from mariners 6 and 7

Mariners 6 and 7 photographs of the equatorial region of Mars document a three-stage evolution of that part of the Martian surface: (1) High- and intermediate-albedo cratered terrains in Meridiani Sinus, Margaritifer Sinus-Thymiamata, Deucalionis Regio-Sabaeus Sinus, and Hellespontus; (2) low-albedo moderately cratered terrain and dark crater fill in Meridiani Sinus, Thymiamata, and Deucalionis Regio-Sabaeus Sinus and possible volcanism in the Hellas-Hellespontus border; and (3) high-albedo surficial deposits, banked-up crater fill, a possible bright-ray crater in Meridiani Sinus, chaotic terrain on the edge of the Margaritifer Sinus mesa, featureless terrain in Hellas and Edom, sinuous channel-like reentrants on scarps at the Hellas-Hellespontus boundary. Regional faulting seems to have occurred following formation of the old cratered plains and prior to formation of low-albedo plains in Meridiani Sinus and also prior to formation of canyon-like reentrants and featureless terrain along the Hellas-Hellespontus boundary.Mars has had a complex history of dynamic evolution, possibly analogous to the more stable regions of Earth. Its geochemical differentiation and thermal regime should account for long-term postaccretional tectonic and volcano-tectonic processes as well as for fluid media on its surface sufficient to cause erosion, including the cutting of large canyons.     

Semi-monthly mean sea-level pressure maps for the Mediterranean area

Summary Semi-monthly mean sea-level pressure maps for the Mediterranean and adjacent areas are presented. Isobars have been drawn at 1-millibar intervals. The most significant features on the maps and the advantages of the mode of presentation are discussed briefly.

---

Zusammenfassung Es werden auf das Meeresniveau bezogene halbmonatliche mittlere Luftdruckkarten für das Mittelmeergebiet und die anstoßenden Länder vorgelegt. Die Isobaren wurden für Millibarabstände gezeichnet. Die wichtigsten Resultate der Karten und die Vorzüge der Darstellungsweise werden kurz besprochen.

---

Résumé Présentation de cartes de la pression moyenne semi-mensuelle, réduite au niveau de la mer, de la région méditerranéenne et des contrées voisines. Les isobares sont tracées de millibar en millibar. Brève discussion des traits principaux des cartes et des avantages de la méthode de représentation.

---

---

With 25 Figures.

---

The work reported in this paper has been supported by the Geophysics Research Division of the Air Force Cambridge Research Center, under Contract AF 19 (122)-466.