Simple approaches and inversion methods retrieve particle size parameters of atmospheric desert aerosols

1998 ◽  
Vol 32 (2) ◽  
pp. 239-245 ◽  
Author(s):  
Victoria E. Cachorro
Keyword(s):  
Particle Size ◽  
Inversion Methods ◽  
And Inversion

scholarly journals A study of the approaches used to retrieve aerosol extinction, as applied to limb observations made by OSIRIS and SCIAMACHY

2018 ◽  
Vol 11 (6) ◽  
pp. 3433-3445 ◽  
Author(s):  
Landon A. Rieger ◽  
Elizaveta P. Malinina ◽  
Alexei V. Rozanov ◽  
John P. Burrows ◽  
Adam E. Bourassa ◽  
...  
Keyword(s):  
Particle Size ◽  
Radiative Transfer ◽  
A Priori ◽  
Stratospheric Aerosol ◽  
Aerosol Extinction ◽  
Transfer Modelling ◽  
Inversion Techniques ◽  
And Inversion ◽  
Good Agreement

Abstract. Limb scatter instruments in the UV–vis spectral range have provided long-term global records of stratospheric aerosol extinction important for climate records and modelling. While comparisons with occultation instruments show generally good agreement, the source and magnitude of the biases arising from retrieval assumptions, approximations in the radiative transfer modelling and inversion techniques have not been thoroughly characterized. This paper explores the biases between SCIAMACHY v1.4, OSIRIS v5.07 and SAGE II v7.00 aerosol extinctions through a series of coincident comparisons as well as simulation and retrieval studies to investigate the cause and magnitude of the various systematic differences. The effect of a priori profiles, particle size assumptions, radiative transfer modelling, inversion techniques and the different satellite datasets are explored. It is found that the assumed a priori profile can have a large effect near the normalization point, as well as systematic influence at lower altitudes. The error due to particle size assumptions is relatively small when averaged over a range of scattering angles, but individual errors depend on the particular scattering angle, particle size and measurement vector definition. Differences due to radiative transfer modelling introduce differences between the retrieved products of less than 10 % on average, but can introduce vertical structure. The combination of the different scenario simulations and the application of both algorithms to both datasets enable the origin of some of the systematic features such as high-altitude differences when compared to SAGE II to be explained.

scholarly journals A study of the approaches used to retrieve aerosol extinction, as applied to limb observations made by OSIRIS and SCIAMACHY

2018 ◽  
Author(s):  
Landon A. Rieger ◽  
Elizaveta P. Malinina ◽  
Alexei V. Rozanov ◽  
John P. Burrows ◽  
Adam E. Bourassa ◽  
...  
Keyword(s):  
Particle Size ◽  
Radiative Transfer ◽  
A Priori ◽  
Stratospheric Aerosol ◽  
Aerosol Extinction ◽  
Measurement Vector ◽  
Transfer Modelling ◽  
Inversion Techniques ◽  
And Inversion ◽  
Good Agreement

Abstract. Limb scatter instruments in the UV-Vis spectral range have provided longterm global records of stratospheric aerosol extinction important for climate records and modelling. While comparisons with occultation instruments show generally good agreement, the source and magnitude of the biases arising from retrieval assumptions, approximations in the radiative transfer modelling, and inversion techniques has not been thoroughly characterized. This paper explores the biases between SCIAMACHY v1.4, OSIRIS v5.07 and SAGE II v7.00 aerosol extinctions through a series of coincident comparisons as well as simulation and retrieval studies to investigate the cause and magnitude of the various systematic differences. The effect of a priori profiles, particle size assumptions, radiative transfer modelling, inversion techniques, and the different satellite datasets are explored. It is found that the assumed a priori profile can have a large effect near the normalization point, as well as systematic influence at lower altitudes. The error due to particle size assumptions is relatively small when averaged over a range of scattering angles, but individual errors depend on the particular scattering angle, particle size and measurement vector definition. Differences due to radiative transfer modelling introduce differences between the retrieved products of less than 10 % on average, but can introduce vertical structure. The combination of the different scenario simulations and the application of both algorithms to both datasets enable the origin of some of the systematic features such as high altitude differences when compared to SAGE II to be explained.

Action research on division of fractions

1966 ◽  
Vol 13 (4) ◽  
pp. 293-295
Author(s):  
Patricia M. Bergen
Keyword(s):  
Action Research ◽  
Sixth Grade ◽  
Common Denominator ◽  
Inversion Methods ◽  
Division Of Fractions ◽  
The Common ◽  
And Inversion ◽  
Reciprocal Method

Division of fractions has caused confusion for pupils and irresolution in teachers for many years. Its rationalization in terms sixth-grade pupils will understand is difficult. Even the authorities on the teaching of arithmetic disagree on the best method of coping with this problem. Recommendations encompass the common denominator and inversion methods and, of late, the complex fraction (reciprocal) method.

scholarly journals 2.5D vs 1D AEM Forward and Inversion Methods at a Survey Scale : A Case Study

2018 ◽  
Vol 2018 (1) ◽  
pp. 1-8
Author(s):  
J. Silic ◽  
R. Paterson ◽  
D. FitzGerald
Keyword(s):  
Inversion Methods ◽  
And Inversion

scholarly journals Data inversion methods to determine sub-3 nm aerosol size distributions using the particle size magnifier

2018 ◽  
Vol 11 (7) ◽  
pp. 4477-4491 ◽  
Author(s):  
Runlong Cai ◽  
Dongsen Yang ◽  
Lauri R. Ahonen ◽  
Linlin Shi ◽  
Frans Korhonen ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Em Algorithm ◽  
Kernel Function ◽  
Function Method ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Inversion Methods ◽  
The Em Algorithm ◽  
Stepwise Method

Abstract. Measuring particle size distribution accurately down to approximately 1 nm is needed for studying atmospheric new particle formation. The scanning particle size magnifier (PSM) using diethylene glycol as a working fluid has been used for measuring sub-3 nm atmospheric aerosol. A proper inversion method is required to recover the particle size distribution from PSM raw data. Similarly to other aerosol spectrometers and classifiers, PSM inversion can be deduced from a problem described by the Fredholm integral equation of the first kind. We tested the performance of the stepwise method, the kernel function method (Lehtipalo et al., 2014), the H&A linear inversion method (Hagen and Alofs, 1983), and the expectation–maximization (EM) algorithm. The stepwise method and the kernel function method were used in previous studies on PSM. The H&A method and the expectation–maximization algorithm were used in data inversion for the electrical mobility spectrometers and the diffusion batteries, respectively (Maher and Laird, 1985). In addition, Monte Carlo simulation and laboratory experiments were used to test the accuracy and precision of the particle size distributions recovered using four inversion methods. When all of the detected particles are larger than 3 nm, the stepwise method may report false sub-3 nm particle concentrations because an infinite resolution is assumed while the kernel function method and the H&A method occasionally report false sub-3 nm particles because of the unstable least squares method. The accuracy and precision of the recovered particle size distribution using the EM algorithm are the best among the tested four inversion methods. Compared to the kernel function method, the H&A method reduces the uncertainty while keeping a similar computational expense. The measuring uncertainties in the present scanning mode may contribute to the uncertainties of the recovered particle size distributions. We suggest using the EM algorithm to retrieve the particle size distributions using the particle number concentrations recorded by the PSM. Considering the relatively high computation expenses of the EM algorithm, the H&A method is recommended for preliminary data analysis. We also gave practical suggestions on PSM operation based on the inversion analysis.

Flexible Provenance Tracing

2013 ◽  
pp. 157-175
Author(s):  
Liwei Wang ◽  
Henning Koehler ◽  
Ke Deng ◽  
Xiaofang Zhou ◽  
Shazia Sadiq
Keyword(s):  
Inversion Method ◽  
Data Provenance ◽  
Time Requirement ◽  
Provenance Information ◽  
Inversion Methods ◽  
Provenance Data ◽  
Source Data ◽  
History Of ◽  
And Inversion ◽  
Derivation Process

The description of the origins of a piece of data and the transformations by which it arrived in a database is termed the data provenance. The importance of data provenance has already been widely recognized in database community. The two major approaches to representing provenance information use annotations and inversion. While annotation is metadata pre-computed to include the derivation history of a data product, the inversion method finds the source data based on the situation that some derivation process can be inverted. Annotations are flexible to represent diverse provenance metadata but the complete provenance data may outsize data itself. Inversion method is concise by using a single inverse query or function but the provenance needs to be computed on-the-fly. This paper proposes a new provenance representation which is a hybrid of annotation and inversion methods in order to achieve combined advantage. This representation is adaptive to the storage constraint and the response time requirement of provenance inversion on-the-fly.

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