scholarly journals Autoregressive Spectral Averaging Estimator

2017 ◽  
Author(s):  
Chu-An Liu ◽  
Biing-Shen Kuo ◽  
Wen-Jen Tsay
Keyword(s):  
Spectral Averaging

scholarly journals Parametrizations of Liquid and Ice Clouds’ Optical Properties in Operational Numerical Weather Prediction Models

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 89
Author(s):  
Harel. B. Muskatel ◽  
Ulrich Blahak ◽  
Pavel Khain ◽  
Yoav Levi ◽  
Qiang Fu
Keyword(s):  
Optical Properties ◽  
Numerical Weather Prediction ◽  
Radiation Transfer ◽  
Prediction Models ◽  
Weather Prediction ◽  
Effective Size ◽  
Asymmetry Factor ◽  
Numerical Weather ◽  
Numerical Weather Prediction Models ◽  
Spectral Averaging

Parametrization of radiation transfer through clouds is an important factor in the ability of Numerical Weather Prediction models to correctly describe the weather evolution. Here we present a practical parameterization of both liquid droplets and ice optical properties in the longwave and shortwave radiation. An advanced spectral averaging method is used to calculate the extinction coefficient, single scattering albedo, forward scattered fraction and asymmetry factor (bext, v, f, g), taking into account the nonlinear effects of light attenuation in the spectral averaging. An ensemble of particle size distributions was used for the ice optical properties calculations, which enables the effective size range to be extended up to 570 μm and thus be applicable for larger hydrometeor categories such as snow, graupel, and rain. The new parameterization was applied both in the COSMO limited-area model and in ICON global model and was evaluated by using the COSMO model to simulate stratiform ice and water clouds. Numerical weather prediction models usually determine the asymmetry factor as a function of effective size. For the first time in an operational numerical weather prediction (NWP) model, the asymmetry factor is parametrized as a function of aspect ratio. The method is generalized and is available on-line to be readily applied to any optical properties dataset and spectral intervals of a wide range of radiation transfer models and applications.

scholarly journals Improving Wind Profiler–Measured Winds Using Coplanar Spectral Averaging

2004 ◽  
Vol 21 (11) ◽  
pp. 1671-1678 ◽  
Author(s):  
Robert Schafer ◽  
Susan K. Avery ◽  
Kenneth S. Gage ◽  
Paul E. Johnston ◽  
D. A. Carter
Keyword(s):  
Quality Control ◽  
Fuzzy Logic ◽  
Consensus Method ◽  
Wind Profiler ◽  
Christmas Island ◽  
Simulated Wind ◽  
Spectral Averaging

Abstract A method is presented that increases the detectability of weak clear-air signals by averaging Doppler spectra from coplanar wind profiler beams. The method, called coplanar spectral averaging (CSA), is applied to both simulated wind profiler spectra and to 1 yr of archived spectra from a UHF profiler at Christmas Island (1 October 1999–30 September 2000). A collocated 50-MHz wind profiler provides a truth for evaluating the CSA technique. In the absence of precipitation, it was found that CSA, when combined with a fuzzy logic quality control, increases the height coverage of the 1-hourly averaged UHF profiler winds by over 600 m (two range gates). CSA also increased the number of good wind estimates at each observation range by about 10%–25% over the standard consensus method.

Spectral averaging of the point spread function for Yohkoh's SXT

Solar Physics ◽  
1996 ◽  
Vol 168 (1) ◽  
pp. 215-217
Author(s):  
David C. Weston ◽  
Loren W. Acton
Keyword(s):  
Point Spread Function ◽  
Point Spread ◽  
Spread Function ◽  
Spectral Averaging

scholarly journals INTERPRETATION OF STALL PRECURSOR SIGNATURES

2021 ◽  
pp. 1-15
Author(s):  
Christoph Brandstetter ◽  
Xavier Ottavy ◽  
Benoit Paoletti ◽  
Sina C Stapelfeldt
Keyword(s):  
Cross Correlation ◽  
Sensor Placement ◽  
Experimental Studies ◽  
Measurement Data ◽  
Post Processing ◽  
Correlation Methods ◽  
Stall Precursor ◽  
Processing Techniques ◽  
Highly Loaded ◽  
Spectral Averaging

Abstract A specific phenomenon that has been observed in many experimental studies on turbomachinery compressors and fans is discussed under the term ‘rotating instabilities’. It is associated to a local aerodynamic phenomenon, typically occurring in the tip region at highly loaded near stall conditions and often linked to blade vibrations. Even though the effect has been discussed over more than two decades, a very ambiguous interpretation still prevails. A particular problem is that certain signatures in measurement data are often considered to characterize the phenomenon despite possible misinterpretations. The present paper illustrates that a specific image of a pulsating disturbance that has been established in the 1990s needs to be reconsidered. At the example of a recent investigation on a composite fan the difficulties concerning sensor placement and post-processing techniques is discussed with a focus on spectral averaging, isolation of non-synchronous phenomena and multi-sensor cross-correlation methods.

Spectral averaging of small-amplitude sine-Gordon wave trains

1988 ◽  
Vol 38 (9) ◽  
pp. 4419-4430 ◽  
Author(s):  
J. W. Larson ◽  
E. R. Tracy
Keyword(s):  
Small Amplitude ◽  
Wave Trains ◽  
Spectral Averaging

Vibration-based wind turbine planetary gearbox fault diagnosis using spectral averaging

Wind Energy ◽  
2015 ◽  
Vol 19 (9) ◽  
pp. 1733-1747 ◽  
Author(s):  
Jae Yoon ◽  
David He ◽  
Brandon Van Hecke ◽  
Thomas J. Nostrand ◽  
Junda Zhu ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Wind Turbine ◽  
Planetary Gearbox ◽  
Spectral Averaging
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