Analysis of Oscillatory Modes of the Magnetic Field of Solar Facular Formations

Geomagnetism and Aeronomy - Quasi-periodical variations in the magnetic fields of long-living, small-scale magnetic structures, solar facular formations (FFs), are analyzed. We used the method of...     

Numerical Simulation of Sub-Terahertz Thermal Emission: RADYN Code

Geomagnetism and Aeronomy - The temporal evolution of thermal bremsstrahlung in the sub-terahertz range is calculated for F-CHROMA models of the flare chromosphere and transition region (...     

Role of land surface parameterizations on modeling cold-pooling events and low-level jets

Land surface parameterization schemes play a significant role in the accuracy of meso-local scale numerical models by accounting for the exchange of energy and water between the soil and the atmosphere. The role of land surface processes during large-scale cold-pooling events was studied with two land surface schemes (LSMs) in the Advanced Research Weather Forecasting model (ARW). Model evaluation was complex due to the surface and boundary layer interactions at different temporal and spatial scales as revealed by a scale dependent variance analysis. Wavelet analysis was used for the first time to analyze the model errors with specific focus on land surface processes. The ARW model was also evaluated for the formation of a low-level jet (LLJ). It is shown that vertical resolution in the model boundary layer played a significant role in determining the characteristics of LLJ, which influenced the lower boundary layer structure and moisture distribution. The results showed that the simulated low-level jet over southern Georgia was sensitive to the land surface parameterization and led to a significant difference in the boundary layer exchange. The jet shear played a crucial role in the maintenance of turbulence and weak shear caused excessive radiative cooling leading to unrealistic cold pools in the model. The results are important for regional downscaling as the excessive cold pools that are simulated in the model can go unnoticed.     

Determination of liquid water content and reserve of cumulonimbus cloudiness from meteorological radar information

The study of the liquid water content and reserve of convective cloudiness accompanied by the rain showers, thunderstorms, and hail is carried out. The values of liquid water content and reserve were obtained by means of computations on the basis of the radar characteristics of cumulonimbus cloudiness as well as with the aid of a number of empirical dependences. It was demonstrated that the use of meteorological radar information for the purpose of computation of the microphysical cloud characteristics such as liquid water content and reserve enables to supplement and specify the data of the ground-based meteorological and aerological observations.     

Description of radiation conditions and evaluation of the date of <Superscript>137</Superscript>Cs release to the atmosphere using the radionuclide transfer model coupled with the forecasts by the mesoscale hydrodynamic model

The estimates of ¹³⁷Cs emissions from the accident happened in Elektrostal at the beginning of April 12, 2013 are presented. The transport of radionuclides and their dry and wet deposition on the surface are computed using the Lagrangian stochastic model of the NOSTRADAMUS software package worked out by Nuclear Safety Institute of Russian Academy of Sciences. Prognostic fields of wind (horizontal and vertical components) in the lower troposphere, precipitation, and vertical and horizontal turbulence diffusivity coefficients in the lower atmosphere (up to 4 km) were used as input data. Prognostic fields were obtained using the WRF-ARW numerical mesoscale model.     

Long-term oscillations of sunspots and a special class of artifacts in SOHO/MDI and SDO/HMI data

A specific type of artifacts (named as “p2p”), that originate due to displacement of the image of a moving object along the digital (pixel) matrix of receiver are analyzed in detail. The criteria of appearance and the influence of these artifacts on the study of long-term oscillations of sunspots are deduced. The obtained criteria suggest us methods for reduction or even elimination of these artifacts. It is shown that the use of integral parameters can be very effective against the “p2p” artifact distortions. The simultaneous observations of sunspot magnetic field and ultraviolet intensity of the umbra have given the same periods for the long-term oscillations. In this way the real physical nature of the oscillatory process, which is independent of the artifacts have been confirmed again. A number of examples considered here confirm the dependence between the periods of main mode of the sunspot magnetic field long-term oscillations and its strength. The dependence was derived earlier from both the observations and the theoretical model of the shallow sunspot. The anti-phase behavior of time variations of sunspot umbra area and magnetic field of the sunspot demonstrates that the umbra of sunspot moves in long-term oscillations as a whole: all its points oscillate with the same phase.