The magnetic-field geometry in polar ray structures of the solar corona

Variations in the positions of the intersection points of tangents to ray structures in the polar corona of the Sun during the solar cycle are considered. At first glance, the decrease in the distance q between the tangent intersection point and the center of the solar disk during activity maximum contradicts harmonic analyses that indicate that the relative weight of higher harmonics in the global field increases during this period. Indeed, the higher the harmonic number in an axisymmetric field, the closer the intersection point of the field-line tangents (the magnetic focus) to the solar surface. It is shown that q for a field composed of two harmonics with opposite polarities at the poles can be smaller than q for either of them taken alone. A simple model representing the global field using the third and seventh harmonics is analyzed; this model can reproduce quite satisfactorily the observed dynamics of magnetic foci of the polar field.     

Integrated geophysical surveys on railroads in permafrost areas

The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engi...     

Downflow of the Antarctic shelf water at the shelf and continental slope of the Commonwealth Sea in the summer season and its effect on the bottom water formation in the Southern Ocean

In the summer seasons of 2004–2007, the intensive runoff (cascading) of the Antarctic shelf water (ASW) down the shelf and continental slope was revealed thanks to the recording of numerous thermohaline profiles across the shelf and continental slope of the Commonwealth Sea and Prydz Bay. The quickly executed profiles (4–10 h) with submesoscale resolution (near the shelf’s edge, the scale was even eddy-determinative, i.e., within 1.9–5.6 km), in combination with the fine-structure sounding and fine vertical resolution of the near-bottom boundary layer, provided a qualitatively new level of understanding the natural data. The detailed analysis of the temperature, salinity, and density patterns revealed the regularities and peculiarities of the ASW shelf and slope cascading. The intensive ASW cascading near the shelf break and lower part of the slope can be forced (appearing as discrete frontal meanders) or free (appearing as discrete plumes) and often has a wave-eddy character. The field observational data confirmed the obtained representative estimates of the elements of the ASW slope cascading. The basic area of the ASW formation is near the Amery Shelf Ice, from where the ASW spreads to the northwest, goes around the Fram Bank, and flows down the continental slope. The evaluative contribution of the ASW slope cascading to the ventilation of the deep and slope water of the Southern Ocean (near the shelf break 70 km long where the ASW cascading was observed) is Q _K = 0.04–0.24 Sv, which agrees well with the analogous estimates obtained in other regions of the Antarctic.     

Peculiarities of Dense Water Cascading off the Deep Part of Antarctic Continental Slope (A Case Study for the Commonwealth Sea)

The developed approach to the calculation and construction of adequate local and common fields of potential density for the whole continental slope (to 2000 m) allows the representative detailed analysis of the downflow of cold and dense shelfwaters in all parts ofthe slope (cascading) in the Commonwealth Sea including the poorly explored deep part. Most often the slope cascading is manifested in the form of discrete meanders (in the steep part of the slope) or discrete plumes (both in the steep and deep parts). More rarely, it occurs in the form of intrusions and eddies (lenses). The pattern and stability of cascading depend on the slope steepness. The detected local irregularities of bottom topography also affect the cascading: they lead to the instability of density flows, intrusive layering, and eddy formation.     

Polar meteorology: Results of Russian research in 2011–2014

A review of the results of Russian polar research performed in 2011–2014 is provided. It is based on material prepared by the Commission on Polar Meteorology of the National Geophysical Committee, Russian Academy of Sciences, for the National Report on Meteorology and Atmospheric Sciences submitted to General Assembly XXVI of the International Union of Geodesy and Geophysics¹ [1].     

Analysis of the Large-Scale Dynamics of Surface Waters in the Southern Ocean with the Help of Lagrangian Drifters

We summarize the results of reconstruction of the monthly average surface circulation in the Southern Ocean according to the paths of autonomous drifting buoys launched in the course of the First Global Geophysical Experiment (FGGE) according to the Program of Investigation of Global Atmospheric Processes in 1978–1980. The data of numerical analysis reveal significant annual and seasonal variability in the behavior of the integral characteristics of the Antarctic Circumpolar Current, the west extension of the Agulhas Current, the zone of convergence of the Falkland and Brasil Currents, and the cyclonic gyres in the Weddell and Ross Seas. It is established that the dynamics of the large-scale surface circulation in the Southern Ocean can be described by two or three empirical orthogonal modes. In general, we observe a strong correlation between the locations of the zones with high kinetic energy of currents and the zones of bottom rise.     

Results of Russian Studies of Polar Meteorology in 2015–2018

Izvestiya, Atmospheric and Oceanic Physics - This is a review of the results from Russian polar research in 2015–2018 prepared by the Commission on Polar Meteorology of the National...     

Positional evolution of magnetic foci in the polar regions of the Sun with the phase of the solar activity cycle

The behavior of magnetic foci—intersection points of tangents to ray structures in the polar corona of the Sun—is studied. This behavior reflects the evolution of the large-scale magnetic field near the poles, and is one of only a few sources of information on the polar magnetic field of the Sun. For the first time, the positions of the magnetic foci are plotted as a function of the solar-cycle phase for a full cycle, based not only on total-eclipse images but also on daily coronal observations in the FeIX and FeX (171 Å) lines carried out with the EIT telescope on the SOHO satellite. The temporal behavior of the foci over a cycle differs appreciably from that inferred from isolated observations during eclipses. The curve agrees fairly well with the model of the global-field evolution suggested by us previously.