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Title:Development of an accurate 3D Monte Carlo broadband atmospheric radiative transfer model
Author(s):Jones, Alexandra L.
Director of Research:Di Girolamo, Larry
Doctoral Committee Chair(s):Di Girolamo, Larry
Doctoral Committee Member(s):Jewett, Brian; Rauber, Robert; Riemer, Nicole
Department / Program:Atmospheric Sciences
Discipline:Atmospheric Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Radiative transfer
Monte Carlo
Abstract:Radiation is the ultimate source of energy that drives our weather and climate. It is also the fundamental quantity detected by satellite sensors from which earth's properties are inferred. Radiative energy from the sun and emitted from the earth and atmosphere is redistributed by clouds in one of their most important roles in the atmosphere. Without accurately representing these interactions we greatly decrease our ability to successfully predict climate change, weather patterns, and to observe our environment from space. The remote sensing algorithms and dynamic models used to study and observe earth's atmosphere all parameterize radiative transfer with approximations that reduce or neglect horizontal variation of the radiation field, even in the presence of clouds. Despite having complete knowledge of the underlying physics at work, these approximations persist due to perceived computational expense. In the current context of high resolution modeling and remote sensing observations of clouds, from shallow cumulus to deep convective clouds, and given our ever advancing technological capabilities, these approximations have been exposed as inappropriate in many situations. This presents a need for accurate 3D spectral and broadband radiative transfer models to provide bounds on the interactions between clouds and radiation to judge the accuracy of similar but less expensive models and to aid in new parameterizations that take into account 3D effects when coupled to dynamic models of the atmosphere. Developing such a state of the art model based on the open source, object-oriented framework of the I3RC Monte Carlo Community Radiative Transfer ("IMC-original'") Model is the task at hand. It has involved incorporating (1) thermal emission sources of radiation ("IMC+emission model"), allowing it to address remote sensing problems involving scattering of light emitted at earthly temperatures as well as spectral cooling rates, (2) spectral integration across an arbitrary range of the electromagnetic spectrum ("MCBRaT-3D" model) to produce heating rates relevant to atmospheric dynamics, and (3) developing tools to interface between the model and databases of single scattering properties of the real atmosphere. Special attention has been paid to practical aspects of implementation for high performance computing on Blue Waters. Incremental tests of the accuracy of each new component have been performed based on carefully designed analytical solutions, culminating in the "MCBRaT-3D" model's ability to reproduce a profile of broadband atmospheric heating rate from a published intercomparison study and its initial use to provide benchmarking results for the evaluation of other 3D models. The models, tools, and databases developed herein provide a significant contribution to the field of atmospheric science, especially by making them publicly available for further development and use. They will enable quantitative evaluations of radiative transfer models and parameterizations by providing a highly accurate solution to many 3D radiative transfer problems encountered in the atmospheric sciences.
Issue Date:2016-01-20
Rights Information:Copyright 2016 by Alexandra L. Jones. All rights reserved.
Date Available in IDEALS:2016-07-07
Date Deposited:2016-05

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