The influence of NCEP-data assimilated into COMMA-LIM on the 16-day wave

The general circulation model COMMA-LIM solves the primitive equations on a sphere using gridpoints. The relative large interval between adjacent gridpoints (5° × 5.6° latitude versus longitude) causes an incorrect meridional temperature gradient in the coarsly resolved troposphere that leads to too weak winds there, particularly in the lower winter stratosphere above the polar region. By using the technique of nudging 11-year averaged NCEP zonal mean temperature data were assimilated into COMMA-LIM. This means that longitudinal dependent processes as calculated by the model still influence the atmosphere. The nudging method has improved not only the lower atmosphere, but also the middle atmospheric jets show a more realistic behaviour. A numerical experiment by forcing the 16-day wave was carried out in order to investigate the influence of an improved background circulation on the vertical propagation of planetary waves.Das globale Zirkulationsmodell COMMA-LIM berechnet die primitiven Gleichungen auf einem Kugelgitter. Der relativ große Gitterabstand von 5°× 5.6° in Breite und Länge und die grobe vertikale Auflösung führen zu einem inkorrekten meridionalen Temperaturgradienten in der Troposphäre, so dass die troposphärischen Jets und der polare Winterwirbel zu schwach ausgeprägt sind. Mit Hilfe der Methode des Nudging wurden in den unteren 30 km der Atmosphäre 11-Jahres gemittelte NCEP Reanalysedaten des Temperaturfeldes assimiliert. Dabei wurde nur der zonale Mittelwert der berechneten Temperatur an die Reanalysedaten relaxiert, so dass die Antriebsterme, die von COMMA-LIM berechnet werden, erhalten bleiben. Durch diese Methode wurden Wind- und Temperaturfeld sowohl in der Troposphäre als auch in der mittleren Atmosphäre verbessert. Ein Experiment zur Ausbreitung der 16-Tage Welle wurde unter den neuen Bedingungen durchgeführt, und der Einfluß der veränderten Atmosphäre auf die vertikale Wellenausbreitung wurde untersucht

DEVELOPMENT OF STRUCTURES FROM SOLID WOOD FOR OBJECTS OF INFRASTRUCTURE

New prefabricated lightweight structures made of solid wood with connections for joining and building metal screws for wood are proposed. Manufacture and assembly of basic elements-bars with a cross-section of 15x15 cm can be carried out in line conditions on the simplest woodworking equipment. The use of local tim-ber material has a number of advantages (ecological, economic and operational). The description of structures with manufacturing process, examples of buildings with vaulted and hipped roofing, connection arrangement, preparation of experimental samples with the use of new equipment of the National Research Moscow State University of Civil Engineering are given. The method of analysis with allowance for plastic deformations is under consideration. It provides additional economic advantages. The analysis is carried out by the method of integral estimates developed by Prof. V.M. Bondarenko for reinforced concrete structures and adapted to wooden structures by Prof. K.P. Pyatikrestovsky. Special strength criteria are used for the analysis of decks working together with the ribs (in a combined stressed state). It is planned to build buildings for various purposes in the ar-eas of development of the Far North of Russia

The influence of NCEP-data assimilated into COMMA-LIM on the 16-day wave

The general circulation model COMMA-LIM solves the primitive equations on a sphere using gridpoints. The relative large interval between adjacent gridpoints (5° × 5.6° latitude versus longitude) causes an incorrect meridional temperature gradient in the coarsly resolved troposphere that leads to too weak winds there, particularly in the lower winter stratosphere above the polar region. By using the technique of nudging 11-year averaged NCEP zonal mean temperature data were assimilated into COMMA-LIM. This means that longitudinal dependent processes as calculated by the model still influence the atmosphere. The nudging method has improved not only the lower atmosphere, but also the middle atmospheric jets show a more realistic behaviour. A numerical experiment by forcing the 16-day wave was carried out in order to investigate the influence of an improved background circulation on the vertical propagation of planetary waves.Das globale Zirkulationsmodell COMMA-LIM berechnet die primitiven Gleichungen auf einem Kugelgitter. Der relativ große Gitterabstand von 5°× 5.6° in Breite und Länge und die grobe vertikale Auflösung führen zu einem inkorrekten meridionalen Temperaturgradienten in der Troposphäre, so dass die troposphärischen Jets und der polare Winterwirbel zu schwach ausgeprägt sind. Mit Hilfe der Methode des Nudging wurden in den unteren 30 km der Atmosphäre 11-Jahres gemittelte NCEP Reanalysedaten des Temperaturfeldes assimiliert. Dabei wurde nur der zonale Mittelwert der berechneten Temperatur an die Reanalysedaten relaxiert, so dass die Antriebsterme, die von COMMA-LIM berechnet werden, erhalten bleiben. Durch diese Methode wurden Wind- und Temperaturfeld sowohl in der Troposphäre als auch in der mittleren Atmosphäre verbessert. Ein Experiment zur Ausbreitung der 16-Tage Welle wurde unter den neuen Bedingungen durchgeführt, und der Einfluß der veränderten Atmosphäre auf die vertikale Wellenausbreitung wurde untersucht

Arctic Stratosphere Circulation Changes in the 21st Century in Simulations of INM CM5

Simulations of Institute of Numerical Mathematics (INM) coupled climate model 5th version for the period from 2015 to 2100 under moderate (SSP2-4.5) and severe (SSP5-8.5) scenarios of greenhouse gases growth are analyzed to investigate changes of Arctic polar stratospheric vortex, planetary wave propagation, Sudden Stratospheric Warming frequency, Final Warming dates, and meridional circulation. Strengthening of wave activity propagation and a stationary planetary wave number 1 in the middle and upper stratosphere, acceleration of meridional circulation, an increase of winter mean polar stratospheric volume (Vpsc) and strengthening of Arctic stratosphere interannual variability after the middle of 21st century, especially under a severe scenario, were revealed. March monthly values of Vpsc in some winters could be about two times more than observed ones in the Arctic stratosphere in the spring of 2011 and 2020, which in turn could lead to large ozone layer destruction. Composite analysis shows that “warm” winters with the least winter mean Vpsc values are characterized by strengthening of wave activity propagation from the troposphere into the stratosphere in December but weaker propagation in January–February in comparison with winters having the largest Vpsc values

Semi-annual variation of excited hydroxyl emission at mid-latitudes

Ground-based observations show a phase shift in semi-annual variation of excited hydroxyl (OH∗) emissions at mid-latitudes (43∘ N) compared to those at low latitudes. This differs from the annual cycle at high latitudes. We examine this behaviour by utilising an OH∗ airglow model which was incorporated into a 3D chemistry–transport model (CTM). Through this modelling, we study the morphology of the excited hydroxyl emission layer at mid-latitudes (30–50∘ N), and we assess the impact of the main drivers of its semi-annual variation: temperature, atomic oxygen, and air density. We found that this shift in the semi-annual cycle is determined mainly by the superposition of annual variations of temperature and atomic oxygen concentration. Hence, the winter peak for emission is determined exclusively by atomic oxygen concentration, whereas the summer peak is the superposition of all impacts, with temperature taking a leading role

Arctic Stratosphere Circulation Changes in the 21st Century in Simulations of INM CM5

Simulations of Institute of Numerical Mathematics (INM) coupled climate model 5th version for the period from 2015 to 2100 under moderate (SSP2-4.5) and severe (SSP5-8.5) scenarios of greenhouse gases growth are analyzed to investigate changes of Arctic polar stratospheric vortex, planetary wave propagation, Sudden Stratospheric Warming frequency, Final Warming dates, and meridional circulation. Strengthening of wave activity propagation and a stationary planetary wave number 1 in the middle and upper stratosphere, acceleration of meridional circulation, an increase of winter mean polar stratospheric volume (Vpsc) and strengthening of Arctic stratosphere interannual variability after the middle of 21st century, especially under a severe scenario, were revealed. March monthly values of Vpsc in some winters could be about two times more than observed ones in the Arctic stratosphere in the spring of 2011 and 2020, which in turn could lead to large ozone layer destruction. Composite analysis shows that “warm” winters with the least winter mean Vpsc values are characterized by strengthening of wave activity propagation from the troposphere into the stratosphere in December but weaker propagation in January–February in comparison with winters having the largest Vpsc values

Simulation of the ENSO influence on the extra-tropical middle atmosphere

Abstract The impact of the El Niño Southern Oscillation (ENSO) on the Northern Hemisphere mid-winter zonal wind, temperature, and stationary planetary waves (SPWs) is evaluated using the Middle and Upper Atmosphere Model and Modern-Era Retrospective Analysis for Research and Applications (MERRA). The composites determined using simulated ensembles and MERRA winters with different ENSO phases show that the mean zonal wind in the stratosphere at higher-middle latitudes is weaker and polar region is warmer, and the activity of SPW1 is higher during El Niño events. The simulated and observed SPW2 amplitude behaves in the opposite way, and it is stronger in the stratosphere during La Niña. The observed changes of SPW1 and SPW2 amplitudes under La Niña and El Niño events should affect an efficiency of the stratosphere–troposphere coupling in different longitudinal sectors through the changes in horizontal distributions of the downward wave activity flux