scholarly journals A new ionospheric tomographic algorithm — constrained multiplicative algebraic reconstruction technique (CMART)

2010 ◽  
Vol 119 (4) ◽  
pp. 489-496 ◽  
Author(s):  
Debao Wen ◽  
Sanzhi Liu
Keyword(s):  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
Algebraic Reconstruction

scholarly journals Limb scatter ozone retrieval from 10 to 60 km using a Multiplicative Algebraic Reconstruction Technique

2008 ◽  
Vol 8 (3) ◽  
pp. 11853-11877 ◽  
Author(s):  
D. A. Degenstein ◽  
A. E. Bourassa ◽  
C. Z. Roth ◽  
E. J. Llewellyn
Keyword(s):  
Vertical Profile ◽  
Retrieval Algorithm ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Vertical Profiles ◽  
Number Density ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
One Dimensional ◽  
Upper Troposphere ◽  
Algebraic Reconstruction

Abstract. The OSIRIS instrument onboard the Odin spacecraft routinely measures vertical profiles of spectrally dispersed, limb scattered sunlight from the upper troposphere into the lower mesosphere. These measurements are used to retrieve the ozone number density vertical profile over the altitude range from 10 to 60 km using the SaskMART Multiplicative Algebraic Reconstruction Technique, which is a one dimensional modification of an existing two-dimensional tomographic retrieval algorithm. This technique allows for the consistent merging of the absorption information from radiance measurements at wavelengths in the Chappuis and the Hartley-Huggins bands at each iteration of the inversion. The effectiveness of the retrieval is demonstrated using a set of coincident SAGE II occultation measurements that show a mean bias of less than 2% from 18 to 53 km.

BIFURCATION ANALYSIS OF ITERATIVE IMAGE RECONSTRUCTION METHOD FOR COMPUTED TOMOGRAPHY

2008 ◽  
Vol 18 (04) ◽  
pp. 1219-1225 ◽  
Author(s):  
TETSUYA YOSHINAGA ◽  
YOSHIHIRO IMAKURA ◽  
KEN'ICHI FUJIMOTO ◽  
TETSUSHI UETA
Keyword(s):  
Computed Tomography ◽  
Image Reconstruction ◽  
Computational Method ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Algebraic Reconstruction Technique ◽  
Reconstruction Algorithms ◽  
Iterative Image Reconstruction ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
Algebraic Reconstruction

Of the iterative image reconstruction algorithms for computed tomography (CT), the power multiplicative algebraic reconstruction technique (PMART) is known to have good properties for speeding convergence and maximizing entropy. We analyze here bifurcations of fixed and periodic points that correspond to reconstructed images observed using PMART with an image made of multiple pixels and we investigate an extended PMART, which is a dynamical class for accelerating convergence. The convergence process for the state in the neighborhood of the true reconstructed image can be reduced to the property of a fixed point observed in the dynamical system. To investigate the speed of convergence, we present a computational method of obtaining parameter sets in which the given real or absolute values of the characteristic multiplier are equal. The advantage of the extended PMART is verified by comparing it with the standard multiplicative algebraic reconstruction technique (MART) using numerical experiments.

scholarly journals Limb scatter ozone retrieval from 10 to 60 km using a multiplicative algebraic reconstruction technique

2009 ◽  
Vol 9 (17) ◽  
pp. 6521-6529 ◽  
Author(s):  
D. A. Degenstein ◽  
A. E. Bourassa ◽  
C. Z. Roth ◽  
E. J. Llewellyn
Keyword(s):  
Vertical Profile ◽  
Retrieval Algorithm ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Vertical Profiles ◽  
Number Density ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
One Dimensional ◽  
Upper Troposphere ◽  
Algebraic Reconstruction

Abstract. The OSIRIS instrument onboard the Odin spacecraft routinely measures vertical profiles of spectrally dispersed, limb scattered sunlight from the upper troposphere into the lower mesosphere. These measurements are used to retrieve the ozone number density vertical profile using the SaskMART Multiplicative Algebraic Reconstruction Technique, which is a one dimensional modification of an existing two-dimensional tomographic retrieval algorithm. The retrieved profile extends from the cloud top to 60 km. In the absence of clouds the retrieval extends down to 10 km. This technique allows for the consistent merging of the absorption information from radiance measurements at wavelengths in the Chappuis and the Hartley-Huggins bands at each iteration of the inversion. The effectiveness of the retrieval is demonstrated using a set of coincident SAGE II occultation measurements that show a mean bias of less than 2% from 18 to 53 km.

The retrieval of vertical profiles of the ozone number density using Chappuis band absorption information and a multiplicative algebraic reconstruction technique

2007 ◽  
Vol 85 (11) ◽  
pp. 1225-1243 ◽  
Author(s):  
C Z Roth ◽  
D A Degenstein ◽  
A E Bourassa ◽  
E J Llewellyn
Keyword(s):  
Radiative Transfer Model ◽  
Transfer Model ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Number Density ◽  
Multiplicative Algebraic Reconstruction Technique ◽  
Ozone Profile ◽  
Band Absorption ◽  
Good Agreement ◽  
Algebraic Reconstruction

A new algorithm, SaskMART, is presented that uses observations of limb-scattered sunlight and a radiative transfer model to determine the ozone number-density profile up to 35 km altitude. In practice, clouds limit the lower extent of the retrieval to around 15 km but if the troposphere is clear the retrieval can be extended to altitudes as low as 10 km. SaskMART is an iterative Multiplicative Algebraic Reconstruction Technique that generates accurate results and is insensitive to the initial estimate of the ozone profile. Examples are presented using the OSIRIS limb-scattered radiance measurements and good agreement has been found when these results are compared with those derived from SAGE II measurements. PACS Nos.: 33.20.Kf, 33.20.Lg, 42.68.Ca, 42.68.Mj, 92.60.H–, 92.60.hd

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