Parallelism detection of visibility meter’s probe beam and the effect on extinction coefficient measurement

Abstract. Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 μm is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 μm is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 μm aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40 μm aerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 μm channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

Download Full-text

New Method of Aerosol Extinction Coefficient Measurement

Acta Optica Sinica ◽

10.3788/aos201434.0101001 ◽

2014 ◽

Vol 34 (1) ◽

pp. 0101001

Author(s):

宫纯文 Gong Chunwen ◽

李学彬 Li Xuebin ◽

李建玉 Li Jianyu ◽

曹亚楠 Cao Yanan ◽

朱文越 Zhu Wenyue ◽

...

Keyword(s):

Extinction Coefficient ◽

New Method ◽

Aerosol Extinction ◽

Coefficient Measurement ◽

Aerosol Extinction Coefficient

Download Full-text

A method for improving the accuracy of an extinction coefficient measurement of weakly absorbing interference layers

Modeling Aspects in Optical Metrology VII ◽

10.1117/12.2525068 ◽

2019 ◽

Author(s):

Van Ba Nguyen ◽

Lyudmila Aleksandrovna Gubanova ◽

Dinh Bao D. B. Bui

Keyword(s):

Extinction Coefficient ◽

Coefficient Measurement

Download Full-text

Toward a combined SAGE II-HALOE aerosol climatology: an evaluation of HALOE version 19 stratospheric aerosol extinction coefficient observations

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-13933-2012 ◽

2012 ◽

Vol 12 (6) ◽

pp. 13933-13965

Author(s):

L. W. Thomason

Keyword(s):

Extinction Coefficient ◽

Stratospheric Aerosol ◽

Substantial Improvement ◽

Data Sets ◽

Aerosol Extinction ◽

Scientific Applications ◽

Quality Product ◽

Coefficient Measurement ◽

Derived Data ◽

Aerosol Extinction Coefficient

Abstract. Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 μm is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances. The 3.40 μm is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 μm aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40 μm aerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 μm channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

Download Full-text

The method of determining the metrological performance of unit reference standards of reflection coefficient in waveguides at millimeter waves

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-1-59-63 ◽

2020 ◽

pp. 59-63

Author(s):

A.S. Bondarenko ◽

A.S. Borovkov ◽

I.M. Malay ◽

V.A. Semyonov

Keyword(s):

Reflection Coefficient ◽

Millimeter Waves ◽

Primary Standard ◽

Reference Standards ◽

Measurement Scale ◽

Current State ◽

Coefficient Measurement ◽

Mathematical Equations ◽

Electrodynamic Modeling ◽

Metrological Performance

The analysis of the current state of the reflection coefficient measurements in waveguides at millimeter waves is carried out. An approach for solving the problem of reproducing the reflection coefficient measurement scale is proposed. Mathematical equations, which are the basis of the reflection coefficient measurement equation are obtained. The method of determining the metrological performance of reflection coefficient unit’s reference standards is developed. The results of electrodynamic modeling and analytical calculations by the developed method are compared. It is shown that this method can be used for reproducing the reflection coefficient unit in the development of the State primary standard.

Download Full-text

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

MRS Proceedings ◽

10.1557/proc-770-i3.2 ◽

2003 ◽

Vol 770 ◽

Cited By ~ 1

Author(s):

Nathanael Smith ◽

Max J. Lederer ◽

Marek Samoc ◽

Barry Luther-Davies ◽

Robert G. Elliman

Keyword(s):

Probe Beam ◽

Time Resolution ◽

Pump Beam ◽

Silicon Nanocrystals ◽

Continuous Wave ◽

Optical Gain ◽

Optical Pump ◽

Time Resolved ◽

Pump Probe ◽

Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

Download Full-text