0000000000056579

AUTHOR

Karri Muinonen

0000-0001-8058-2642

showing 3 related works from this author

Controlled time integration for the numerical simulation of meteor radar reflections

2016

We model meteoroids entering the Earth[U+05F3]s atmosphere as objects surrounded by non-magnetized plasma, and consider efficient numerical simulation of radar reflections from meteors in the time domain. Instead of the widely used finite difference time domain method (FDTD), we use more generalized finite differences by applying the discrete exterior calculus (DEC) and non-uniform leapfrog-style time discretization. The computational domain is presented by convex polyhedral elements. The convergence of the time integration is accelerated by the exact controllability method. The numerical experiments show that our code is efficiently parallelized. The DEC approach is compared to the volume …

010504 meteorology & atmospheric sciencesComputer scienceMETEORPLASMATIC OBJECTSRADAR REFLECTIONS01 natural sciencesplasmatic objectslaw.inventionINTEGRAL EQUATIONSlawRadar010303 astronomy & astrophysicsSpectroscopyEARTH ATMOSPHEREvolume integral equationRadiationPLASMANUMERICAL MODELSMathematical analysisFinite differenceNUMERICAL METHODMETEORSAtomic and Molecular Physics and OpticsCALCULATIONSControllabilityDISCRETE EXTERIOR CALCULUSAstrophysics::Earth and Planetary AstrophysicsMAGNETOPLASMADiscretizationRADAR REFLECTIONTIME DOMAIN ANALYSISVOLUME INTEGRAL EQUATIONdiscrete exterior calculusELECTROMAGNETIC SCATTERINGOpticsFINITE DIFFERENCE TIME DOMAIN METHOD0103 physical sciencesSCATTERINGTime domainmeteorsNUMERICAL METHODS0105 earth and related environmental sciencesta113ta114Computer simulationbusiness.industryta111Finite-difference time-domain methodRADARDiscrete exterior calculuselectromagnetic scatteringradar reflectionsELECTROMAGNETIC METHODmeteoritbusinessJournal of Quantitative Spectroscopy and Radiative Transfer
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Ray optics for absorbing particles with application to ice crystals at near-infrared wavelengths

2018

Abstract Light scattering by particles large compared to the wavelength of incident light is traditionally solved using ray optics which considers absorption inside the particle approximately, along the ray paths. To study the effects rising from this simplification, we have updated the ray-optics code SIRIS to take into account the propagation of light as inhomogeneous plane waves inside an absorbing particle. We investigate the impact of this correction on traditional ray-optics computations in the example case of light scattering by ice crystals through the extended near-infrared (NIR) wavelength regime. In this spectral range, ice changes from nearly transparent to opaque, and therefore…

010504 meteorology & atmospheric sciencesOpacityspektroskopiaIce crystalsPhysics::OpticsRay optics01 natural sciencesPOLARIZED-LIGHT SCATTERING114 Physical sciencesLight scattering010309 opticsScatteringMEDIAOptics0103 physical sciencesABSORPTIONInhomogeneous wavesCIRRUSray opticsSpectroscopy0105 earth and related environmental sciencesPhysicsta113absorbing mediaRadiationta115Geometrical opticsIce crystalsta114Scatteringbusiness.industryscatteringCLOUDSkiteetRayAtomic and Molecular Physics and OpticsoptiikkaSOLAR-RADIATIONWavelengthMAXWELLS EQUATIONSAbsorbing mediainhomogeneous wavesLight scattering by particlesPHASE MATRIXGEOMETRIC-OPTICSbusinessice crystalsAPPROXIMATION
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How much is enough? : The convergence of finite sample scattering properties to those of infinite media

2021

We study the scattering properties of a cloud of particles. The particles are spherical, close to the incident wavelength in size, have a high albedo, and are randomly packed to 20% volume density. We show, using both numerically exact methods for solving the Maxwell equations and radiative-transfer-approximation methods, that the scattering properties of the cloud converge after about ten million particles in the system. After that, the backward-scattered properties of the system should estimate the properties of a macroscopic, practically infinite system. (C) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.o…

010504 meteorology & atmospheric scienceseducationparticulate random mediapienhiukkasetoptiset ominaisuudet01 natural sciences114 Physical sciencesVolume densityScatteringsymbols.namesakelaskennallinen tiedeConvergence (routing)Radiative transferRadiative transferMaxwellin yhtälötsirontaSpectroscopy0105 earth and related environmental sciencesPhysicsRadiationScatteringscatteringAlbedoSample (graphics)Atomic and Molecular Physics and OpticsComputational physicsWavelengthMaxwell's equationsMaxwell equationsradiative transferParticulate random mediasymbolsapproksimointi
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