Accession Number : ADP007337

Title :   Freezing and Thawing of Soils Under the Influence of 300- and 90-Year Periods of Temperature Fluctuation,

Corporate Author : MOSCOW STATE UNIV (USSR) DEPT OF GEOLOGY

Personal Author(s) : Romanovsky, V.E. ; Garagula, L.S. ; Seregina, N.V.

Report Date : MAR 1992

Pagination or Media Count : 6

Abstract : Mathematical modeling of perennial freeze and thaw is used in geocryology to solve both scientific and engineering problems. The surface temperature of a substrate is given as either a constant (stationary problem) or a function with a fixed period of fluctuation (periodic problem). In this paper a numerical permafrost model is developed for the southern Siberia region to study the influence of rhythmic climate change on the dynamics of permafrost. The mathematical model is represented as a two-dimensional heat conduction problem for a moist substrate with the latent heat effect for complex geological structures. This model takes into account a complex periodic temperature change at the soil surface and a stable heat flow at the lower and lateral boundaries for a steady domain. The enthalpy method to arrive at a numerical solution for this problem is used. It has been realized as a fully implicit local one-dimensional finite-difference scheme on an irregular grid. The calculations of the dynamics of temperature fields and permafrost boundaries are discussed to evaluate this scheme for the southern permafrost region of Eastern Siberia. The modeled results show that transects of temperature fields along some profiles (particularly at sites with complex geological structures) contain more information about permafrost dynamics than do ground temperature profiles from isolated boreholes.

Descriptors :   *CLIMATE, *HEAT TRANSMISSION, *MATHEMATICAL MODELS, *PERMAFROST, *SOILS, *TEMPERATURE, *THAWING, BOREHOLES, BOUNDARIES, DYNAMICS, ENGINEERING, ENTHALPY, FLOW, FUNCTIONS, GRIDS, HEAT, LATENT HEAT, MODELS, ONE DIMENSIONAL, PROFILES, REGIONS, SIBERIA, SITES, STRUCTURES, SUBSTRATES, SURFACE TEMPERATURE, SURFACES, TWO DIMENSIONAL, ARCTIC REGIONS, SYMPOSIA.

Subject Categories : Geography
      Snow, Ice and Permafrost
      Meteorology
      Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE