scholarly journals Polar low le Cygne: Satellite observations and numerical simulations

2004 ◽  
Vol 130 (598) ◽  
pp. 1075-1102 ◽  
Author(s):  
Chantal Claud ◽  
Guenther Heinemann ◽  
Elmer Raustein ◽  
Lynn McMurdie
Keyword(s):  
Numerical Simulations ◽  
Satellite Observations ◽  
Polar Low

scholarly journals Quasi-separatrix Layers Induced by Ballooning Instability in Near-Earth Magnetotail

2019 ◽  
Author(s):  
Ping Zhu ◽  
Zechen Wang ◽  
Jun Chen ◽  
Xingting Yan ◽  
Rui Liu
Keyword(s):  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Solar Physics ◽  
Close Correlation ◽  
Satellite Observations ◽  
Two Dimensional ◽  
3 Dimensional ◽  
Ballooning Instability ◽  
3D Geometry ◽  
Alternative Means

Abstract. Magnetic reconnection processes in the near-Earth magnetotail can be highly 3-dimensional (3D) in geometry and dynamics, even though the magnetotail configuration itself is nearly two dimensional due to the symmetry in the dusk-dawn direction. Such reconnection processes can be induced by the 3D dynamics of nonlinear ballooning instability. In this work, we explore the global 3D geometry of the reconnection process induced by ballooning instability in the near-Earth magnetotail by examining the distribution of quasi-separatrix layers associated with plasmoid formation in the entire 3D domain of magnetotail configuration, using an algorithm previously developed in context of solar physics. The 3D distribution of quasi-separatrix layers (QSLs) as well as their evolution directly follows the plasmoid formation during the nonlinear development of ballooning instability in both time and space. Such a close correlation demonstrates a strong coupling between the ballooning and the corresponding reconnection processes. It further confirms the intrinsic 3D nature of the ballooning-induced plasmoid formation and reconnection processes, in both geometry and dynamics. In addition, the reconstruction of the 3D QSL geometry may provide an alternative means for identifying the location and timing of 3D reconnection sites in magnetotail from both numerical simulations and satellite observations.

A Polar Low Observed Over the Korea Strait on 11 February 2011: High-resolution Numerical Simulations

2017 ◽  
Vol 17 (3) ◽  
pp. 55-67 ◽  
Author(s):  
Yujin Kim ◽  
◽  
Mirae Hong ◽  
Jae Gyoo Lee ◽  
◽  
...  
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
Korea Strait ◽  
Polar Low

scholarly journals A ‘hurricane-like’ polar low fuelled by sensible heat flux: high-resolution numerical simulations

2012 ◽  
Vol 138 (666) ◽  
pp. 1308-1324 ◽  
Author(s):  
Ivan Føre ◽  
Jón Egill Kristjánsson ◽  
Erik W. Kolstad ◽  
Thomas J. Bracegirdle ◽  
Øyvind Saetra ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Resolution ◽  
Numerical Simulations ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Polar Low

scholarly journals Assessment of the solar energy potential in Greece using ground-based measurements, satellite observations and numerical simulations of radiative transfer models

2018 ◽  
Author(s):  
Παναγιώτης-Νεκτάριος Κοσμόπουλος
Keyword(s):  
Solar Energy ◽  
Radiative Transfer ◽  
Numerical Simulations ◽  
Satellite Observations ◽  
Surface Radiation ◽  
Energy Potential ◽  
Radiative Transfer Models ◽  
Transfer Models

Η παρούσα διδακτορική διατριβή πραγματεύεται την εκτίμηση του ηλιακού δυναμικού στον Ελλαδικό χώρο με επίγειες και δορυφορικές παρατηρήσεις και αριθμητικές προσομοιώσεις μοντέλων διάδοσης της ακτινοβολίας. Αρχικά χρησιμοποιήθηκαν πυρανόμετρα από το Ελληνικό Δίκτυο Ηλιακής Ενέργειας και το δίκτυο σταθμών του Εθνικού Αστεροσκοπείου Αθηνών με σκοπό την αξιολόγηση προγνώσεων ηλιακής ενέργειας 1 και 2 ημερών μπροστά από το μοντέλο MM5. Το ολικό δυναμικό ηλιακής ενέργειας βρέθηκε να κυμαίνεται μεταξύ 1,5 και 1,9 MWh/m2 με τη νέφωση να προκαλεί αύξηση των σφαλμάτων πρόγνωσης της τάξης του 10%. Εν συνεχεία, εκτιμήθηκε η επίδραση των αιωρούμενων σωματιδίων στην επιφανειακή ηλιακή ακτινοβολία, εστιάζοντας σε ένα έντονο επεισόδιο σκόνης, αναδεικνύοντας τις υψηλές απώλειες ηλιακής ενέργειας της τάξης του 80 και 50% για τα συγκεντρωτικά (CSP) και τα φωτοβολταϊκά (PV) συστήματα αντίστοιχα. Οι παραπάνω αναλύσεις πραγματικών σεναρίων και ατμοσφαιρικών συνθηκών συνεισφέρουν στην κατανόηση αλλά και στην ποσοτικοποίηση του εύρους της επίδρασης που έχουν τα νέφη και τα αιωρούμενα σωματίδια στην ηλιακή ενέργεια, αλλά και στις δυνητικές αστοχίες πρόγνωσης σε περιοχές με υψηλό ηλιακό δυναμικό όπως είναι η Ελλάδα. Ταυτόχρονα, αναπτύχθηκε μια σειρά από καινοτόμα μοντέλα εκτίμησης του δυναμικού ηλιακής ενέργειας τα οποία δύνανται να λειτουργούν επιχειρησιακά και σε πραγματικό χρόνο. Τα μοντέλα αυτά βασίζονται σε πίνακες προσομοιώσεων διάδοσης της ακτινοβολίας, σε τεχνικές υπολογιστικής επιτάχυνσης με νευρωνικά δίκτυα και εξισώσεις πολλαπλής παλινδρόμησης και δορυφορικά δεδομένα εισόδου πραγματικού χρόνου. Η αξιοπιστία τους επαληθεύτηκε με επίγειες μετρήσεις των δικτύων Baseline Surface Radiation Network και Global Atmosphere Watch από τη νότια Αφρική μέχρι τη βόρεια Ευρώπη, ενώ πραγματοποιήθηκε και μια ανάλυση ευαισθησίας των δεδομένων εισόδου (κυρίως νεφών και αιωρούμενων σωματιδίων) ως προς την επίδρασή τους στην ηλιακή ακτινοβολία. Η συνολική προσέγγιση του διδακτορικού στοχεύει στο να αποτελέσει ένα βήμα μπροστά στην πρόγνωση της ηλιακής ενέργειας, στον επιχειρησιακά εφικτό ενεργειακό σχεδιασμό των ηλιακών πάρκων, στην αποτελεσματική εκμετάλλευση της ηλιακής ενέργειας, αλλά και στο να συνεισφέρει στο σχηματισμό πολιτικών που αφορούν τις ανανεώσιμες πηγές ενέργειας.

scholarly journals Combining POLDER-3 satellite observations and WRF-Chem numerical simulations to derive biomass burning aerosol properties over the Southeast Atlantic region

2021 ◽  
Author(s):  
Alexandre Siméon ◽  
Fabien Waquet ◽  
Jean-Christophe Péré ◽  
Fabrice Ducos ◽  
François Thieuleux ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Biomass Burning ◽  
Climate Models ◽  
Single Scattering ◽  
Satellite Observations ◽  
Biomass Combustion ◽  
Absorption Properties ◽  
Brown Carbon ◽  
Aerosol Absorption ◽  
Physico Chemical

Abstract. Aerosol absorption is a key property to assess the radiative impacts of aerosols on climate at both global and regional scales. The aerosol physico-chemical and optical properties remain not sufficiently constrained in climate models, with difficulties to properly represent both the aerosol load and their absorption properties in clear and cloudy scenes, especially for absorbing biomass burning aerosols (BBA). In this study we focus on biomass burning (BB) particle plumes transported above clouds over the Southeast Atlantic (SEA) region off the southwest coast of Africa, in order to improve the representation of their physico-chemical and absorption properties. The methodology is based on aerosol regional numerical simulations from the WRF-Chem coupled meteorology-chemistry model combined with a detailed inventory of BB emissions and various sets of innovative aerosol remote sensing observations, both in clear and cloudy skies from the POLDER-3/PARASOL space sensor. Current literature indicates that some organic aerosol compounds (OC) called "brown carbon" (BrOC), primarily emitted by biomass combustion absorb the ultraviolet-blue radiation more efficiently than pure black carbon (BC). We exploit this specificity by comparing the spectral dependence of the aerosol single scattering albedo (SSA) derived from the POLDER-3 satellite observations in the 443–1020 nm wavelength range with the SSA simulated for different proportions of BC, OC and BrOC at the source level, considering the homogeneous internal mixing state of particles. These numerical simulation experiments are based on two main constraints: maintaining a realistic aerosol optical depth both in clear and above cloudy scenes and a realistic BC/OC mass ratio. Modelling experiments are presented and discussed to link the chemical composition with the absorption properties of BBA and to provide estimates of the relative proportions of black, organic and brown carbon in the African BBA plumes transported over the SEA region for July 2008. The absorbing fraction of organic aerosols in the BBA plumes, i.e., BrOC, is estimated at 2 to 3 %. The simulated mean SSA are 0.81 (565 nm) and 0.84 (550 nm) in clear and above cloudy scenes respectively, in good agreement with those retrieved by POLDER-3 (0.85 ± 0.05 at 565 nm in clear-sky and at 550 nm above clouds) for the studied period.

Satellite observations of a polar low over the Norwegian Sea by special sensor microwave imager, Geosat, and TIROS-N operational vertical sounder

1993 ◽  
Vol 98 (C8) ◽  
pp. 14487 ◽  
Author(s):  
Chantal Claud ◽  
Nelly M. Mognard ◽  
Kristina B. Katsaros ◽  
Alain Chedin ◽  
Noelle A. Scott
Keyword(s):  
Satellite Observations ◽  
Norwegian Sea ◽  
Polar Low ◽  
Microwave Imager

scholarly journals Quasi-separatrix layers induced by ballooning instability in the near-Earth magnetotail

2019 ◽  
Vol 37 (3) ◽  
pp. 325-335
Author(s):  
Ping Zhu ◽  
Zechen Wang ◽  
Jun Chen ◽  
Xingting Yan ◽  
Rui Liu
Keyword(s):  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Strong Coupling ◽  
Solar Physics ◽  
Three Dimensional ◽  
Close Correlation ◽  
Satellite Observations ◽  
Two Dimensional ◽  
Ballooning Instability ◽  
Alternative Means

Abstract. Magnetic reconnection processes in the near-Earth magnetotail can be highly three-dimensional (3-D) in geometry and dynamics, even though the magnetotail configuration itself is nearly two-dimensional due to the symmetry in the dusk–dawn direction. Such reconnection processes can be induced by the 3-D dynamics of nonlinear ballooning instability. In this work, we explore the global 3-D geometry of the reconnection process induced by ballooning instability in the near-Earth magnetotail by examining the distribution of quasi-separatrix layers associated with plasmoid formation in the entire 3-D domain of magnetotail configuration, using an algorithm previously developed in the context of solar physics. The 3-D distribution of quasi-separatrix layers (QSLs) as well as their evolution directly follow the plasmoid formation during the nonlinear development of ballooning instability in both time and space. Such a close correlation demonstrates a strong coupling between the ballooning and the corresponding reconnection processes. It further confirms the intrinsic 3-D nature of the ballooning-induced plasmoid formation and reconnection processes, in both geometry and dynamics. In addition, the reconstruction of the 3-D QSL geometry may provide an alternative means of identifying the location and timing of 3-D reconnection sites in the magnetotail from both numerical simulations and satellite observations.

The Thermal Wake of Kauai Island: Satellite Observations and Numerical Simulations*

2008 ◽  
Vol 21 (18) ◽  
pp. 4568-4586 ◽  
Author(s):  
Yang Yang ◽  
Shang-Ping Xie ◽  
Jan Hafner
Keyword(s):  
Numerical Simulations ◽  
Diurnal Cycle ◽  
Satellite Observations ◽  
Trade Wind ◽  
Strong Wind ◽  
Wake Effect ◽  
Cloud Band ◽  
Warm Advection ◽  
Early Afternoon ◽  
Thermal Wake

Abstract Island thermal effects on the trail cloud band over the central North Pacific are investigated for the lee of Hawaii using satellite observations and a regional atmospheric model. The trail cloud band develops around noon and peaks in cloudiness in the early afternoon. The analysis of numerical simulations of the Kauai wake suggests that a dynamically induced convergence zone forms in the lee of Kauai and Oahu (maximum elevation at 1.5 and 1.2 km, respectively) under the trade wind flow. The island thermal effect significantly modulates the island wake and creates a diurnal cycle of development and decay in the lee cloud band. As solar radiation heats up the island from morning to afternoon, warm air moves downstream (warm advection) from the island in the wake zone, increasing the air temperature, decreasing the air pressure, and enhancing low-level wind convergence in favor of the formation of the trail clouds. Conversely the cold advection during night suppresses cloud formation in the wake. The warm advection and the convergence in the wake increase with the upstream trade wind strength, consistent with satellite observations that the cloudiness increases in the wake under strong wind conditions in the afternoon. The similarity in the trail cloud and its diurnal cycle between Kauai and Oahu suggests that the thermal wake effect is quite common. The conditions for such a thermal wake are discussed.

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