invlib: A generic implementation of Bayesian methods for inverse problems in remote sensing

Examensarbete för masterexamen

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Type: Examensarbete för masterexamen
Master Thesis
Title: invlib: A generic implementation of Bayesian methods for inverse problems in remote sensing
Authors: Pfreundschuh, Simon
Abstract: Spaceborne earth observation missions constitute an essential source of information for climate science. In order to extract physically relevant quantities from the electromagnetic signals recorded by the detector onboard the satellite several data processing steps are required. This process, the so called data retrieval, requires a thorough mathematical formulation as well as an efficient implementation to ensure both the correctness of the retrieved data and the ability to handle large retrievals at a sufficiently high bandwidth. As part of this thesis project the invlib C++ template library has been developed, which implements Bayesian methods for inverse problems arising from the retrieval of remote sensing earth observation data. The library provides functionality for the memory-efficient calculation of maximum a posteriori estimators of Bayesian inverse problems with Gaussian priors and measurement error. This method, known in the field of remote sensing as the optimal estimation method (OEM), has been implemented using generic programming techniques in order to provide a maximum of flexibility and performance to the user of the library. The invlib library has been integrated into the Atmospheric Radiative Transfer Simulator (ARTS), which is a publicly available software package for the simulation of the propagation of electromagnetic radiation through the atmosphere. The integration of the retrieval functionality considerably simplifies the data retrieval workflow with ARTS, which previously required the use of a separate, external software package. In this thesis report the use of the invlib library for tomographic retrievals from the Odin SMR mission is demonstrated. Using the new implementation based on the invlib library, it is now possible to perform the tomographic retrievals of data from a complete half-orbit in a single computation. Furthermore, it is demonstrated how the computations can be parallelized using invlibs generic parallel matrix and vector types. Finally, also the use of the invlib library for the three-dimensional retrieval of simulated data from the MATS satellite mission is illustrated. The principal result of this thesis is a free software C++ template library for remote sensing data retrieval, that emphasizes generality and performance. Furthermore, the invlib library has been integrated into the ARTS software package and the retrieval functionality made available to a large community of existing users. The capabilities of the library to perform and accelerate the solution of real world retrieval problems has been demonstrated by applying it to data from two different earth observation missions.
Keywords: Grundläggande vetenskaper;Optimeringslära, systemteori;Meteorologi och atmosfärforskning;Basic Sciences;Optimization, systems theory;Meteorology and Atmospheric Sciences
Issue Date: 2016
Publisher: Chalmers tekniska högskola / Institutionen för rymd- och geovetenskap
Chalmers University of Technology / Department of Earth and Space Sciences
Collection:Examensarbeten för masterexamen // Master Theses

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