Analysis of the color variability of BL Lac in the visible range during the 1997 outburst

The color variability of BL Lac during the strong 1997 outburst was studied. It was found that the energy distribution in the spectrum of the variable source, which determines the object’s photometric behavior, did not vary during the outburst. It was a power- law spectrum and was flatter than during other, lower-power out-bursts. There is no doubt of the synchrotron nature of the variable source. Translated from Astrofizika, Vol. 43, No. 2, pp. 175-182, April–June, 2000.     

Short-period internal waves in an arctic Fjord (Spitsbergen)

Measurements of temperature and salinity in the frequency range of short-period internal waves are considered. The measurements were carried out in the Van Mijen Fjord in Spitsbergen. The dominating periods of short-period internal waves are equal to a few minutes. They correspond to an internal wave with a dimensionless wavenumber 1/2. The generation of short-period internal waves is determined by external forcing from wind and tide. In winter, when the surface of the fjord is covered with ice, the wind stress is not transferred to the internal oscillations and the spectral level of internal waves decreases.     

Distribution and changes of active layer thickness (ALT) and soil temperature (TTOP) in the source area of the Yellow River using the GIPL model

Active layer thickness (ALT) is critical to the understanding of the surface energy balance, hydrological cycles, plant growth, and cold region engineering projects in permafrost regions. The temperature at the bottom of the active layer, a boundary layer between the equilibrium thermal state (in permafrost below) and transient thermal state (in the atmosphere and surface canopies above), is an important parameter to reflect the existence and thermal stability of permafrost. In this study, the Geophysical Institute Permafrost Model (GIPL) was used to model the spatial distribution of and changes in ALT and soil temperature in the Source Area of the Yellow River (SAYR), where continuous, discontinuous, and sporadic permafrost coexists with seasonally frozen ground. Monthly air temperatures downscaled from the CRU TS3.0 datasets, monthly snow depth derived from the passive microwave remote-sensing data SMMR and SSM/I, and vegetation patterns and soil properties at scale of 1:1000000 were used as input data after modified with GIS techniques. The model validation was carried out carefully with ALT in the SAYR has significantly increased from 1.8 m in 1980 to 2.4 m in 2006 at an average rate of 2.2 cm yr^?1. The mean annual temperature at the bottom of the active layer, or temperature at the top of permafrost (TTOP) rose substantially from ?1.1°C in 1980 to ?0.6°C in 2006 at an average rate of 0.018°C yr^?1. The increasing rate of the ALT and TTOP has accelerated since 2000. Regional warming and degradation of permafrost has also occurred, and the changes in the areal extent of regions with a sub-zero TTOP shrank from 2.4×10⁴ to 2.2×10⁴ km² at an average rate of 74 km² yr^?1. Changes of ALT and temperature have adversely affected the environmental stability in the SAYR.     

The First Reported Pleistocene Beaver,Castor fiber (Castoridae,Rodentia), from the Gobi Altai Region of Mongolia

Doklady Earth Sciences - Here, we report a fragmentary Castor fiber (Linnaeus, 1758) proximal left ulna from Tsagaan Agui Cave (Gobi Altai Mountains, southern Mongolia). This constitutes the first...