scholarly journals Application of Oxygen A-band Equivalent Width for Cloud Optical Depth Measurement

2016 ◽  
Author(s):  
Edward R. Niple ◽  
Herman E. Scott ◽  
John A. Conant ◽  
Stephen H. Jones ◽  
Frank J. Iannarilli ◽  
...  
Keyword(s):  
Optical Depth ◽  
Equivalent Width ◽  
New Technique ◽  
Spectral Radiance ◽  
Cloud Optical Depth ◽  
Depth Measurement ◽  
Visible Band ◽  
A New Technique ◽  
Better Than

Abstract. This paper presents a new technique for measuring Cloud Optical Depth (COD). It is based on ground-based visible band zenith spectral radiances much like the AERONET Cloud-Mode sensors. What is novel in our approach is that we employ absorption in the oxygen A-band as a means of resolving the COD Ambiguity inherent in using up-looking spectral radiances. We describe the algorithm and a sensor that implements it, and compare its performance to AERONET Cloud-Mode measurements collected during the Two Column Aerosol Project (TCAP). Spectral radiance agreement was excellent (better than 1 %) while COD agreement was good.

scholarly journals Application of oxygen A-band equivalent width to disambiguate downwelling radiances for cloud optical depth measurement

2016 ◽  
Vol 9 (9) ◽  
pp. 4167-4179 ◽  
Author(s):  
Edward R. Niple ◽  
Herman E. Scott ◽  
John A. Conant ◽  
Stephen H. Jones ◽  
Frank J. Iannarilli ◽  
...  
Keyword(s):  
Optical Depth ◽  
Near Infrared ◽  
Spectral Radiance ◽  
Retrieval Method ◽  
Cloud Optical Depth ◽  
Depth Measurement ◽  
The Us ◽  
Linear Fit ◽  
Radiation Measurements ◽  
Better Than

Abstract. This paper presents the three-waveband spectrally agile technique (TWST) for measuring cloud optical depth (COD). TWST is a portable field-proven sensor and retrieval method offering a unique combination of fast (1 Hz) cloud-resolving (0.5° field of view) real-time-reported COD measurements. It entails ground-based measurement of visible and near-infrared (VNIR) zenith spectral radiances much like the Aerosol Robotic Network (AERONET) cloud-mode sensors. What is novel in our approach is that we employ absorption in the oxygen A-band as a means of resolving the COD ambiguity inherent in using up-looking spectral radiances. We describe the TWST sensor and algorithm, and assess their merits by comparison to AERONET cloud-mode measurements collected during the US Department of Energy's Atmospheric Radiation Measurements (ARM) Two-Column Aerosol Project (TCAP). Spectral radiance agreement was better than 1 %, while a linear fit of COD yielded a slope of 0.905 (TWST reporting higher COD) and offset of −2.1.

scholarly journals X-Ray Reflectivity Measurements of Surface Roughness Using Energy Dispersive Detection

1990 ◽  
Vol 208 ◽  
Author(s):  
E. Chason ◽  
D. T. Warwick
Keyword(s):  
Surface Roughness ◽  
Excellent Agreement ◽  
Ion Bombardment ◽  
Energy Dispersive ◽  
New Technique ◽  
Scattering Angle ◽  
X Ray ◽  
Growth Chambers ◽  
A New Technique ◽  
Better Than

ABSTRACTWe describe a new technique for measuring X-ray reflectivity using energy dispersive X-ray detection. The benefits of this method are the use of a fixed scattering angle and parallel detection of all energies simultaneously. These advantages make the technique more compatible with growth chambers and useable with laboratory X-ray sources. We find excellent agreement between the calculated Fresnel reflectivity and the reflectivity obtained from a smooth Ge (001) surface. Reflectivities obtained during 500 eV Xe ion bombardment of Ge surfaces demonstrate the sensitivity of the technique to be better than 1 Å.

scholarly journals Accurate timing of a particle beam using laser ablation

2001 ◽  
Vol 19 (2) ◽  
pp. 237-239 ◽  
Author(s):  
A. BALLARD ◽  
K. BONIN
Keyword(s):  
Laser Ablation ◽  
Particle Beam ◽  
Ablation Plume ◽  
New Technique ◽  
Cluster Beam ◽  
Beam Path ◽  
Light Force ◽  
A New Technique ◽  
Better Than

We report on a new technique that we used to accurately time the velocity of a cluster beam. It involves deflecting particles away from their usual beam path by scattering with an ablation plume. We were able to time the occurrence of a C60 cluster beam to better than 0.2%. This technique was critical in recent light-force polarizabilities experiments.

scholarly journals Assessing a Cloud Optical Depth Retrieval Algorithm with Model-Generated Data and the Frozen Turbulence Assumption

2004 ◽  
Vol 61 (23) ◽  
pp. 2951-2956 ◽  
Author(s):  
H. W. Barker ◽  
C. F. Pavloski ◽  
M. Ovtchinnikov ◽  
E. E. Clothiaux
Keyword(s):  
Time Series ◽  
Optical Depth ◽  
Retrieval Algorithm ◽  
Surface Site ◽  
Cloud Optical Depth ◽  
Radiation Data ◽  
Shallow Cumulus ◽  
Radiance Data ◽  
Radiation Measurements ◽  
Better Than

Abstract A cloud optical depth retrieval algorithm that utilizes time series of solar irradiance and zenith downwelling radiance data collected at a fixed surface site is assessed using model-generated cloud fields and simulated radiation measurements. To date, the retrieval algorithm has only been assessed using instantaneous cloud fields in which time series were mimicked via the frozen turbulence assumption. In this study, time series of radiation data are generated for use by the algorithm from a series of snapshots of an evolving and advecting cloud field, with values of optical depth retrieved for clouds occurring at the midpoint of the time series. This approach resembles conditions encountered in the field much better than those arising from the convenient frozen turbulence assumption. Values of optical depth are also retrieved for the same cloud field by employing the frozen turbulence approach. For the field of broken, shallow cumulus considered here, differences between the two sets of retrievals are small. This suggests that the encouraging results obtained thus far for this retrieval algorithm have not been secured falsely by the frozen turbulence assumption.

Cloud optical depth measurement comparison between a Raman-Mie and Mie elastic lidar

2008 ◽  
Author(s):  
Yonghua Wu ◽  
Shuki Chaw ◽  
Barry Gross ◽  
Fred Moshary ◽  
Sam Ahmed
Keyword(s):  
Optical Depth ◽  
Cloud Optical Depth ◽  
Depth Measurement

scholarly journals A New Technique for Simulation the Zakharov–Kuznetsov Equation

2018 ◽  
Vol 14 (2) ◽  
pp. 7912-7920
Author(s):  
Mohammed Sabah Abdul-Wahab ◽  
A. S. J. Al-Saif
Keyword(s):  
Variational Iteration Method ◽  
Approximate Solutions ◽  
New Technique ◽  
Test Problems ◽  
Initial Condition ◽  
Two Dimensional ◽  
Analysis Method ◽  
Homotopy Analysis ◽  
A New Technique ◽  
Better Than

In this article, a new technique is proposed to simulated two-dimensional Zakharov–Kuznetsov equation with the initial condition. The idea of this technique is based on Taylors' series in its derivation. Two test problems are presented to illustrate the performance of the new scheme. Analytical approximate solutions that we obtain are compared with variational iteration method (VIM) and homotopy analysis method (HAM). The results show that the new scheme is efficient and better than the other methods in accuracy and convergence.

scholarly journals Comparison of mid-latitude single and mixed-phase cloud optical depth from co-located infrared spectrometer and backscatter LiDAR measurements

2021 ◽  
Author(s):  
Gianluca Di Natale ◽  
Marco Barucci ◽  
Claudio Belotti ◽  
Giovanni Bianchini ◽  
Francesco D'Amato ◽  
...  
Keyword(s):  
Optical Depth ◽  
Far Infrared ◽  
Spectral Radiance ◽  
Observation System ◽  
Ice Clouds ◽  
Cloud Optical Depth ◽  
Lidar Measurements ◽  
Infrared Spectrometer ◽  
Mobile Observation ◽  
Ice Water

Abstract. The longwave downwelling spectral radiance measurements performed by means of the Far-Infrared Radiation Mobile Observation System (FIRMOS) spectrometer at the summit of the Mt. Zugspitze (German Alps) in the Winter 2018–2019, allowed to retrieve the optical and micro-physical properties of ice, mixed and water clouds, showing a good agreement of the statistical relationship between the ice water path and the ice optical depth with the ones from previous works. In this paper the optical depths retrieved from FIRMOS are initially compared with selected cases calculated from backscattering Light Detection And Ranging (LiDAR) data by using a transmittance method. Then, in order to compare the whole FIRMOS dataset, the power-law relationship between backscattering and extinction is used to apply the Klett method and automatize the routine. Minimizing the root mean square differences, the exponent of the relationship, the so called backscatter-extinction coefficient ratio, is assessed to be 0.85 with a variabiliy in the range 0.60–1.10 for ice clouds and 0.50 with a variability within 0.30–0.70 for mixed and water clouds.

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