Effects of systematic and random errors on the retrieval of particle microphysical properties from multiwavelength lidar measurements using inversion with regularization

Abstract. In this work we study the effects of systematic and random errors on the inversion of multiwavelength (MW) lidar data using the well-known regularization technique to obtain vertically resolved aerosol microphysical properties. The software implementation used here was developed at the Physics Instrumentation Center (PIC) in Troitsk (Russia) in conjunction with the NASA/Goddard Space Flight Center. Its applicability to Raman lidar systems based on backscattering measurements at three wavelengths (355, 532 and 1064 nm) and extinction measurements at two wavelengths (355 and 532 nm) has been demonstrated widely. The systematic error sensitivity is quantified by first determining the retrieved parameters for a given set of optical input data consistent with three different sets of aerosol physical parameters. Then each optical input is perturbed by varying amounts and the inversion is repeated. Using bimodal aerosol size distributions, we find a generally linear dependence of the retrieved errors in the microphysical properties on the induced systematic errors in the optical data. For the retrievals of effective radius, number/surface/volume concentrations and fine-mode radius and volume, we find that these results are not significantly affected by the range of the constraints used in inversions. But significant sensitivity was found to the allowed range of the imaginary part of the particle refractive index. Our results also indicate that there exists an additive property for the deviations induced by the biases present in the individual optical data. This property permits the results here to be used to predict deviations in retrieved parameters when multiple input optical data are biased simultaneously as well as to study the influence of random errors on the retrievals. The above results are applied to questions regarding lidar design, in particular for the spaceborne multiwavelength lidar under consideration for the upcoming ACE mission.

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Effects of systematic and random errors on the retrieval of particle microphysical properties from multiwavelength lidar measurements using inversion with regularization

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-6-4607-2013 ◽

2013 ◽

Vol 6 (3) ◽

pp. 4607-4644 ◽

Cited By ~ 2

Author(s):

D. Pérez-Ramírez ◽

D. N. Whiteman ◽

I. Veselovskii ◽

A. Kolgotin ◽

M. Korenskiy ◽

...

Keyword(s):

Optical Data ◽

Physical Parameters ◽

Random Errors ◽

Additive Property ◽

Nasa Goddard Space ◽

Microphysical Properties ◽

Multi Wavelength ◽

Fine Mode ◽

Systematic And Random Errors ◽

The Individual

Abstract. In this work we study the effects of systematic and random errors on the inversion of multi-wavelength (MW) lidar data, using the well-known regularization technique, to obtain vertically-resolved aerosol microphysical properties. The software implementation used here was developed at the Physics Instrumentation Center (PIC) in Troitsk (Russia) in conjunction with NASA/Goddard Space Flight Center. Its applicability to Raman lidar systems based on backscattering measurements at three wavelengths (355, 532 and 1064 nm) and extinction measurements at two wavelengths (355 and 532 nm) has been demonstrated widely. The systematic error sensitivity is quantified by first determining the retrieved parameters for a given set of optical input data consistent with two different sets of aerosol physical parameters. Then each optical input is perturbed by varying amounts and the inversion is repeated. We find a generally linear dependence of the retrieved errors in the microphysical properties on the induced systematic errors in the optical data. For the retrievals of effective radius, number/surface/volume concentrations and fine mode radius and volume, we found that these results are not significantly affected by the range of the constraints used in inversions. But significant sensitivity was found to the allowed range of the imaginary part of the particle refractive index to reach. Our results also indicate that exist an additive property for the deviations induced by the biases induced in the individual optical data. This permits the results here to be used to predict deviations in retrieved parameters when multiple input optical data are biased as well as to study the influence of random errors on the retrievals. The above results can be applied to questions regarding lidar design, as for example the space-borne multi-wavelength lidar to be deployed in the upcoming ACE mission anticipated to provide optical data with 15% accuracy in each of the lidar channels.

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Simulations of spaceborne multiwavelength lidar measurements and retrievals of aerosol microphysics

10.5194/amt-2016-174 ◽

2016 ◽

Cited By ~ 1

Author(s):

David N. Whiteman ◽

Daniel Perez-Ramirez ◽

Igor Veselovskii ◽

Peter Colarco ◽

Virginie Buchard

Keyword(s):

Surface Area ◽

Satellite Orbit ◽

Global Model ◽

Optical Data ◽

Retrieval Performance ◽

Ancillary Data ◽

Model Simulations ◽

Lidar Measurements ◽

Fine Mode ◽

Multiwavelength Lidar

Abstract. In support of the Aerosol, Clouds, Ecosystems missions, simulations of a spaceborne multiwavelength lidar are performed based on global model simulations of the atmosphere along a satellite orbit track. The yield for aerosol microphysical inversions is quantified and comparisons are made between the aerosol microphysics inherent in the global model and those inverted from both the model's optical data and the simulated lidar measurements, which are based on the model's optical data. We find that yield can be significantly increased if inversions based on reduced optical data are acceptable. In general, retrieval performance is better for cases where the aerosol fine mode dominates. Lack of sensitivity to coarse mode cases is found, in agreement with earlier studies. Surface area is generally the most robustly retrieved quantity. The work here points toward the need for ancillary data to aid in the constraints of the lidar inversions and also for the need for joint inversions involving lidar and polarimeter measurements.

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Systematic and Random Errors Associated with Johnston's Cephalometric Analysis

British Journal of Orthodontics ◽

10.1179/bjo.20.2.101 ◽

1993 ◽

Vol 20 (2) ◽

pp. 101-107 ◽

Cited By ~ 9

Author(s):

Stephen D. Keeling ◽

Sal R. Cabassa ◽

Gregory J. King

Keyword(s):

Random Error ◽

Error Variance ◽

Individual Case ◽

Base Change ◽

Mixed Dentition ◽

Random Errors ◽

Angular Measure ◽

Basal Bone ◽

Systematic And Random Errors ◽

The Individual

This study examined intra- and interexaminer systematic and random errors associated with Johnston's cephalometric method of assessing skeletal and dental changes from pairs of radiographs. Data were obtained from the tracings of radiographs of 30 mixed dentition subjects, who had been treated to correct a Class II malocclusion. Measurements included molar and incisor crown movements relative to basal bone, apical base change, maxillary and mandibular displacement relative to the cranial base, and total molar and overjet reduction. In addition, the change in axial inclination of the incisors and molars was determined. A paired t- test for each pair of replicates for each measure was performed to examine inter- and intra-examiner bias. Estimates of the random error, the coefficient of reliability, and confidence limits (95 per cent level) of a single determination were undertaken. No systematic errors occurred between/within examiners for any linear or angular measure. Interexaminer random errors, based on the standard deviation of the mean difference between replicates, were greater than intra-examiner random errors for 12 out of 13 parameters. Measures assessing molar correction and overjet reduction had the least amount of random error variance within and across judges, while changes in mandibular position had the greatest. Because considerable random errors occurred, the Johnston analysis when used to assess skeletal changes, as well as individual molar and incisor movements, may have limited utility in clinical practice for the individual case.

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Demonstration of Aerosol Property Profiling by Multiwavelength Lidar under Varying Relative Humidity Conditions

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2009jtecha1254.1 ◽

2009 ◽

Vol 26 (8) ◽

pp. 1543-1557 ◽

Cited By ~ 57

Author(s):

I. Veselovskii ◽

D. N. Whiteman ◽

A. Kolgotin ◽

E. Andrews ◽

M. Korenskii

Keyword(s):

Relative Humidity ◽

Complex Refractive Index ◽

Strong Dependence ◽

Radiosonde Data ◽

Optical Data ◽

Physical Parameters ◽

Raman Lidar ◽

Hygroscopic Growth ◽

Fine Mode ◽

Sun Photometer

Abstract The feasibility of using a multiwavelength Mie–Raman lidar based on a tripled Nd:YAG laser for profiling aerosol physical parameters in the planetary boundary layer (PBL) under varying conditions of relative humidity (RH) is studied. The lidar quantifies three aerosol backscattering and two extinction coefficients and from these optical data the particle parameters such as concentration, size, and complex refractive index are retrieved through inversion with regularization. The column-integrated, lidar-derived parameters are compared with results from the AERONET sun photometer. The lidar and sun photometer agree well in the characterization of the fine-mode parameters, however the lidar shows less sensitivity to coarse mode. The lidar results reveal a strong dependence of particle properties on RH. The height regions with enhanced RH are characterized by an increase of backscattering and extinction coefficient and a decrease in the Ångström exponent coinciding with an increase in the particle size. The hygroscopic growth factor calculated for a select case is consistent with previous literature results despite the lack of collocated radiosonde data. These results demonstrate the potential of the multiwavelength Raman lidar technique for the study of aerosol humidification process.

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Statistics and parallaxes

International Astronomical Union Colloquium ◽

10.1017/s0252921100073875 ◽

1978 ◽

Vol 48 ◽

pp. 7-29

Author(s):

T. E. Lutz

Keyword(s):

Experimental Design ◽

Statistical Methods ◽

Review Paper ◽

Systematic Errors ◽

Past Experience ◽

Random Errors ◽

Trigonometric Parallaxes ◽

Systematic And Random Errors

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.

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Evaluation of the SteamVR Motion Tracking System with a Custom-Made Tracker

Applied Sciences ◽

10.3390/app11146390 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6390

Author(s):

Marcin Maciejewski

Keyword(s):

Motion Tracking ◽

Tracking System ◽

Training System ◽

Random Errors ◽

Operational Conditions ◽

Custom Made ◽

Systematic And Random Errors ◽

Position And Orientation ◽

Motion Tracking System ◽

System Operating

The paper presents the research of the SteamVR tracker developed for a man-portable air-defence training system. The tests were carried out in laboratory conditions, with the tracker placed on the launcher model along with elements ensuring the faithful reproduction of operational conditions. During the measurements, the static tracker was moved and rotated in a working area. The range of translations and rotations corresponded to the typical requirements of a shooting simulator application. The results containing the registered position and orientation values were plotted on 3D charts which showed the tracker’s operation. Further analyses determined the values of the systematic and random errors for measurements of the SteamVR system operating with a custom-made tracker. The obtained results with random errors of 0.15 mm and 0.008° for position and orientation, respectively, proved the high precision of the measurements.

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Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar data set – DISCOVER-AQ 2011

Atmospheric Measurement Techniques ◽

10.5194/amt-7-3095-2014 ◽

2014 ◽

Vol 7 (9) ◽

pp. 3095-3112 ◽

Cited By ~ 7

Author(s):

P. Sawamura ◽

D. Müller ◽

R. M. Hoff ◽

C. A. Hostetler ◽

R. A. Ferrare ◽

...

Keyword(s):

Remote Sensing ◽

In Situ Measurements ◽

Index Of Refraction ◽

High Spectral Resolution ◽

Lidar Data ◽

Data Set ◽

Microphysical Properties ◽

Lidar Measurements ◽

Multiwavelength Lidar

Abstract. Retrievals of aerosol microphysical properties (effective radius, volume and surface-area concentrations) and aerosol optical properties (complex index of refraction and single-scattering albedo) were obtained from a hybrid multiwavelength lidar data set for the first time. In July 2011, in the Baltimore–Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne (in situ and remote sensing) and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar data set combines ground-based elastic backscatter lidar measurements at 355 nm with airborne High-Spectral-Resolution Lidar (HSRL) measurements at 532 nm and elastic backscatter lidar measurements at 1064 nm that were obtained less than 5 km apart from each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor in such discrepancies.

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Aerosol microphysical retrievals from Precision Filter Radiometer direct solar radiation measurements and comparison with AERONET

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-99-2014 ◽

2014 ◽

Vol 7 (1) ◽

pp. 99-130 ◽

Cited By ~ 1

Author(s):

S. Kazadzis ◽

I. Veselovskii ◽

V. Amiridis ◽

J. Gröbner ◽

A. Suvorina ◽

...

Keyword(s):

Temporal Resolution ◽

Volume Concentration ◽

Effective Radius ◽

Optical Data ◽

Inversion Method ◽

High Temporal Resolution ◽

Random Errors ◽

Percentage Difference ◽

Filter Radiometer ◽

And Inversion

Abstract. Synchronized sun-photometric measurements from the AERONET-CIMEL and GAW-PFR aerosol networks are used to compare retrievals of the aerosol optical depth, effective radius and volume concentration during a high temporal resolution measurement campaign at the Athens site in the Mediterranean Basin from 14–22 July 2009. During this period, direct sun AOD retrievals from both instruments exhibited small differences in the range 0.01–0.02 despite the presence of a strong dust event. In addition to AERONET-CIMEL inversion data, an independent inversion method was applied that involves expanding the particle size distribution in terms of measurement kernels so as to estimate bulk particle parameters from a linear-estimated combination of the input optical data. AOD measurements obtained from both CIMEL and PFR instruments using this method also showed reasonable agreement. For low aerosol loads (AOD < 0.2), measurements of the effective radius by the PFR were found to be −20% to +30% different from CIMEL values for both direct sun data and inversion data. At higher loads (AOD > 0.4), measurements of the effective radius by the PFR are consistently 20% lower than CIMEL for both direct sun and inversion data. Volume concentrations at low aerosol loads from the PFR are up to 80% higher than the CIMEL for direct sun data, but inversion data suggests that volume concentrations from the PFR are up to 20% lower than the CIMEL under these same conditions. At higher loads, the percentage difference in volume concentrations from the PFR and CIMEL is systematically negative with inversion data predicting differences 30% lower than those obtained from direct sun data. An assessment of the effect of errors in the AOD retrieval on the estimation of PFR bulk parameters was made using Monte Carlo simulations and demonstrated that it is possible to estimate the effective radius with an uncertainty below 60% and the volume concentration with an uncertainty below 65% even when AOD < 0.2 and when the input errors are as high as 10%. Highlights – A comparison of high temporal resolution synchronous CIMEL and PFR direct sun AOD measurement retrievals – Calculation of bulk aerosol microphysics parameters using a linear estimation inversion technique – A comparison of retrieved aerosol volume concentrations and effective radii from CIMEL and PFR inversions – An analysis of the sensitivity of PFR retrievals to random errors on the optical input data

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