Estimating the baroclinic Rossby radius of deformation in the Sea of Okhotsk

The first baroclinic Rossby radius of deformation (R ₁) in the Sea of Okhotsk is estimated using the hydrological datasets from the World Ocean Atlas (WOA) 2001 and WOA 2013. It is established that the maximum values of R ₁ are observed over the Kuril Basin (18–20 km), and its minimum values (1.5–2 km), over the northern shelf of the Sea of Okhotsk. In the central part of the sea R1 varies from 8 to 10 km. The seasonal variability of R1 for both datasets is characterized by the minima in winter and by the maxima in summer. It was found that on the eastern shelf of Sakhalin Island R ₁ reaches the maximum both in November (～6 km) and in April (～4-5 km). According to the obtained estimates of R ₁, the model grid resolution of 3 to 8 km should be used for the eddy-permitting numerical simulation of circulation in the Sea of Okhotsk, and the model grid resolution from 1.5 to 2 km, for the explicit simulation of mesoscale variability.     

Geochemistry of ultrahigh-pressure anatexis: fractionation of elements in the Kokchetav gneisses during melting at diamond-facies conditions

The Kokchetav complex in Kazakhstan contains garnet-bearing gneisses that formed by partial melting of metasedimentary rocks at ultrahigh-pressure (UHP) conditions. Partial melting and melt extraction from these rocks is documented by a decrease in K₂O and an increase in FeO + MgO in the restites. The most characteristic trace element feature of the Kokchetav UHP restites is a strong depletion in light rare earth elements (LREE), Th and U. This is attributed to complete dissolution of monazite/allanite in the melt and variable degree of melt extraction. In contrast, Zr concentrations remain approximately constant in all gneisses. Using experimentally determined solubilities of LREE and Zr in high-pressure melts, these data constrain the temperature of melting to ~1,000 °C. Large ion lithophile elements (LILE) are only moderately depleted in the samples that have the lowest U, Th and LREE contents, indicating that phengite retains some LILE in the residue. Some restites display an increase in Nb/Ta with respect to the protolith. This further suggests the presence of phengite, which, in contrast to rutile, preferentially incorporates Nb over Ta. The trace element fractionation observed during UHP anatexis in the Kokchetav gneisses is significantly different from depletions reported in low-pressure restites, where generally no LREE and Th depletion occurs. Melting at UHP conditions resulted in an increase in the Sm/Nd ratio and a decoupling of the Sm–Nd and Lu–Hf systems in the restite. Further subduction of such restites and mixing with mantle rocks might thus lead to a distinct isotopic reservoir different from the bulk continental crust.     

Pulsations of non-thermal emissions from the solar flare of November 5, 1992 and the trap-plus-precipitation model

The fine structure of the time variations of microwave and hard X-ray emissions from the solar flare of November 5, 1992 was analyzed. On the basis of the wavelet analysis, pulsations of intensity with a period of about 6 s were revealed in both the data sets. The observed time delay between the coronal plasma emission measure maximum and the temperature maximum is consistent with the concept of chromospheric evaporation. The anticorrelation observed between the time profiles of the microwave and hard X-ray emissions and the nature of the time delays between the peaks are associated with the excitation of radial fast magneto-acoustic oscillations in the flare loop (a coronal trap). Consequences of the obtained results are discussed.     

Paleoproterozoic mafic dyke swarms of the Belomorian Province,eastern Fennoscandian Shield

Paleoproterozoic mafic igneous rocks (2450–1970 Ma) are exposed in the form of layered intrusions, dykes, and volcanic rocks in the Karelian, Kola and Murmansk provinces and in the form of dykes and small intrusions in the Belomorian Province, Eastern Fennoscandian Shield. The age and sequence of mafic dyke emplacement during the Paleoproterozoic are very similar in these regions. Further comparisons of geochemical characteristics of mafic dyke swarms in the Belomorian Province and neighboring cratons show considerable similarities.     

Long-lived hot coronal structures observed with CORONAS-F/SPIRIT in the Mg XII line

Large-scale hot features were detected and observed several times high in the solar corona in the high-temperature Mg XII line (T = 5–20 MK, T _max = 10 MK) with the soft X-ray telescope of the SPIRIT instrumentation complex onboard the CORONAS-F spacecraft. These features look like a spider up to 300000 km in size and live up to a few days. Their bright cores observed at heights were from 0.1 to 0.3 solar radii are connected with active regions by darker legs, giant loops. These features are disposed above arcades, which are simultaneously observed in cooler emission lines sensitive to temperatures of 1 to 2 MK. For the core of such a feature observed December 28–29, 2001, Zhitnik et al. (2003a) estimated an electron temperature of 10 MK and a number density of n _e ≈ 10¹⁰ cm^?3. A high activity and an association with eruptive phenomena were found for such features in continuous (up to 20-day) observations with a cadence of 0.6–1.7 min. In the present paper, we discuss the relation of such features to coronal structures, which are known from previous studies. We identify such off-limb features observed with SPIRIT on October 22, November 12, and December 28–29, 2001, with hot upper parts of post-eruptive arcades. The results of multifrequency analysis of these features based on the data obtained in various spectral ranges by different instruments (Yohkoh/SXT, SOHO/EIT, SOHO/LASCO, Nobeyama and SSRT radioheliographs) are briefly discussed. We address the physical conditions of the long-term existence of giant hot coronal structures. It is demonstrated that the post-eruptive energy release must be prolonged and the condition β ? 1 is not satisfied in these structures. It is argued that the so-called “standard flare model” should be better considered as a “standard post-eruptive energy release model.”     

Type-II Spicules as Important Sources of Both Heating and Sustain the Mass Loss of Solar Corona

Geomagnetism and Aeronomy - Heat fluxes from hot open magnetic flux tubes into the surrounding corona as a possible source of corona heating are determined. In order to compensate for radiation and...