Browsing by Keyword "Geophysics"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Accurate calculation of conductive conductances in complex geometries for spacecrafts thermal models(2016-02-15) Garmendia, Iñaki; Anglada, Eva; Vallejo, Haritz; Seco, Miguel; CIRMETAL; MAQUINASThe thermal subsystem of spacecrafts and payloads is always designed with the help of Thermal Mathematical Models. In the case of the Thermal Lumped Parameter (TLP) method, the non-linear system of equations that is created is solved to calculate the temperature distribution and the heat power that goes between nodes. The accuracy of the results depends largely on the appropriate calculation of the conductive and radiative conductances. Several established methods for the determination of conductive conductances exist but they present some limitations for complex geometries. Two new methods are proposed in this paper to calculate accurately these conductive conductances: The Extended Far Field method and the Mid-Section method. Both are based on a finite element calculation but while the Extended Far Field method uses the calculation of node mean temperatures, the Mid-Section method is based on assuming specific temperature values. They are compared with traditionally used methods showing the advantages of these two new methodsItem Jupiter’s Great Red Spot: Strong Interactions With Incoming Anticyclones in 2019(2021-04) Sánchez-Lavega, A.; Anguiano-Arteaga, A.; Iñurrigarro, P.; Garcia-Melendo, E.; Legarreta, J.; Hueso, R.; Sanz-Requena, J. F.; Pérez-Hoyos, S.; Mendikoa, I.; Soria, M.; Rojas, J. F.; Andrés-Carcasona, M.; Prat-Gasull, A.; Ordoñez-Extebarria, I.; Rogers, J. H.; Foster, C.; Mizumoto, S.; Casely, A.; Hansen, C. J.; Orton, G. S.; Momary, T.; Eichstädt, G.; RENOVABLES OFFSHOREJupiter’s Great Red Spot (GRS), a giant anticyclone, is the largest and longest-lived of all the vortices observed in planetary atmospheres. During its history, the GRS has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that interacted in a complex way. In 2018–2020, while having a historically small size, its structure and even its survival appeared to be threatened when a series of anticyclones moving in from the east tore off large fragments of the red area and distorted its shape. In this work, we report observations of the dynamics of these interactions and show that as a result the GRS increased its internal rotation velocity, maintaining its vorticity but decreasing its visible area, and suffering a transient change in its otherwise steady 90-day oscillation in longitude. From a radiative transfer analysis and numerical simulations of the dynamics we show that the interactions affected the upper cloud tops of the GRS. We argue that the intense vorticity of the GRS, together with its larger size and depth compared to the interacting vortices, guarantees its long lifetime.Item Studying cumulative ozone exposures in Europe during a 7-year period(1997-10-27) Bastrup-Birk, Annemarie; Brandt, Jørgen; Zlatev, Zahari; Uria, Ignacio; Centros PRE-FUSION TECNALIA - (FORMER)Ozone is one of the most harmful pollutants in the troposphere. High ozone concentrations can damage plants, animals and humans. The damaging effects depend on the magnitude of a critical level of a special parameter, the cumulative ozone exposure. This is why cumulative ozone exposures must be carefully studied. It is important to determine the relationships between relevant emissions (NOx emissions, human-made VOC emissions, and/or a combination of NOx emissions and human-made VOC emissions) and cumulative ozone exposures All these issues are discussed in this paper. Meteorological data from seven consecutive years, from 1989 to 1995, have been used in the experiments with different scenarios for varying the emissions (the NOx emissions, the human-made VOC emissions, as well as both the NO emissions and the human-made VOC emissions). The particular air pollution model used in this study is the Danish Eulerian Model. Several hundred runs with different input data (meteorological data and/or emission data) have been performed. Advanced visualization techniques are used to interpret the large amount of digital data collected in these runs and to show clearly different trends and relationships that are normally hidden behind millions and millions of numbers. The model results were compared with measurements taken at more than 80 stations located in different European countries. The experiments indicate that it is sufficient to carry out computations over 5 consecutive years in order to eliminate the influence of extreme meteorological conditions (very warm or very cold summer months) on the cumulative ozone exposures, while this effect is clearly seen if less than 5 years are used in the experiments It is shown that the relationship between the emissions (NOx and/or human-made VOC emissions) and the cumulative ozone exposures is in general nonlinear. Finally, it is illustrated that the critical values for ozone exposures are exceeded in most of Europe (in many areas by more than 7 times).