The NIMA Method for Improved Moment Estimation from Doppler Spectra

Morse, Corinne S.; Goodrich, Robert K.; Cornman, Larry

doi:10.1175/1520-0426-19.3.274

Cited by 67 publications

(52 citation statements)

References 16 publications

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“…The 915 DWP is also quality controlled by applying the Weber-Wuertz intermittent clutter rejection algorithm outlined by Bianco et al (2013). Additionally, profiles of horizontal wind from the 915 DWP are obtained by applying the NCAR Improved Moments Algorithm (NIMA; Cornman et al 1998;Morse et al 2002) at 10-min intervals to remove spectral contamination and derive consensus wind components. These profiles (available for 89 cases) are used to assess horizontal wind magnitude changes.…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

Multi-platform Observations Characterizing the Afternoon-to-Evening Transition of the Planetary Boundary Layer in Northern Alabama, USA

Wingo

Knupp

2014

Boundary-Layer Meteorol

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Observations from the University of Alabama in Huntsville campus and groundbased scanning radar for over 140 total spring, summer, and autumn cases are studied to contribute to the relative scarcity of long-term datasets documenting the afternoon-to-evening transition of the planetary boundary layer. A sunset relative frame of reference is employed, focusing on the period 3 h before to 2 h after astronomical sunset, and several findings are consistent with previous investigations. Fluctuating components of wind and temperature computed from nearly collocated surface, Doppler wind profiler, and vertically pointing Doppler lidar measurements show a consistent decline as turbulence intensity diminishes through the transition. When normalized by their initial values, a pattern emerges: temperature variances decline slowly at first then quite abruptly after about 90 min before sunset. After the temperature variances begin to wane, vertical velocity fluctuations decrease, and the rate of their decay increases as vigorous thermal structures diminish. The fastest decline of the horizontal wind variance occurs after an accelerated vertical wind variance decrease, and the horizontal wind fluctuations display the slowest rate of decrease among these quantities. Near-surface humidity measurements show increases in mean water vapour mixing ratio as a steady rise generally beginning about 80 min prior to sunset. Composites of mean lidar vertical motion show final convective-type towers of upward motion occur about an hour before sunset and are coherent through 800 m (all heights a.g.l.). Lidar vertical motion variance at 195 m decreases by more than an order of magnitude approaching sunset, then remains below 0.01 m 2 s −2 for the rest of the studied time frame. Subtle, but steady, increases in both horizontal wind speed and radar-derived horizontal wind convergence above the surface layer (at 300 m) span the entire 5-h time frame. While the convergence results show a broad range, an increase in the mean is clear and found to be statistically significant. Implications

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Section: Data and Analysis Methodsmentioning

confidence: 99%

Multi-platform Observations Characterizing the Afternoon-to-Evening Transition of the Planetary Boundary Layer in Northern Alabama, USA

Wingo

Knupp

2014

Boundary-Layer Meteorol

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“…They were operated in a 5-beam mode with nominal 192-m range gates. We applied the NCAR Improved Moment Algorithm (Morse et al, 2002) to the moments data from the profilers to obtain 30-min average consensus winds. The radiosonde systems were Vaisala DigiCORA ™ systems and used model RS-92 sondes, also manufactured by Vaisala.…”

Section: Instrumentsmentioning

confidence: 99%

The T1-T2 study: evolution of aerosol properties downwind of Mexico City

et al. 2007

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Abstract. As part of a major atmospheric chemistry and aerosol field program carried out in March 2006, a study was conducted in the area to the north and northeast of Mexico City to investigate the evolution of aerosols and their associated optical properties in the first few hours after their emission. The focus of the T1-T2 aerosol study was to investigate changes in the specific absorption α ABS (absorption per unit mass, with unit of m 2 g −1 ) of black carbon as it aged and became coated with compounds such as sulfate and organic carbon, evolving from an external to an internal mixture. Such evolution has been reported in previous studies. The T1 site was located just to the north of the Mexico City metropolitan area; the T2 site was situated approximately 35 km farther to the northeast. Nephelometers, particle soot absorption photometers, photoacoustic absorption spectrometers, and organic and elemental carbon analyzers were used to measure the optical properties of the aerosols and the carbon concentrations at each of the sites. Radar wind profilers and radiosonde systems helped to characterize the meteorology and to identify periods when transport from Mexico City over T1 and T2 occurred. Organic and elemental carbon concentrations at T1 showed diurnal cycles reflecting the nocturnal and early morning buildup from nearby sources, while concentrations at T2 appeared to be more affected by transport from Mexico City. Specific absorption during transport periods was lower than during other times, consistent with the likelihood of fresher emissions being found when the winds blew from Mexico City over T1 and T2. The speCorrespondence to: J. C. Doran (christopher.doran@pnl.gov) cific absorption at T2 was larger than at T1, which is also consistent with the expectation of more aged particles with encapsulated black carbon being found at the more distant location. In situ measurements of single scattering albedo with an aircraft and a ground station showed general agreement with column-averaged values derived from rotating shadowband radiometer data, although some differences were found that may be related to boundary-layer evolution.

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“…Only this signal will then be used for the determination of the wind vector. Several criteria are used to make an "intelligent" selection of the signal (Clothiaux et al, 1994;Gossard, 1997;Griesser, 1998;Cornman et al, 1998;Schumann et al, 1999;Wilfong et al, 1999b;Morse et al, 2000). The emphasis on frequency domain processing was probably caused by the fact that it is much easier to handle spectral data, as the data volume is significantly reduced due to the data compression effect of the periodogram computation and the spectral integration.…”

Section: Statement Of the Problemmentioning

confidence: 99%

Wavelet based methods for improved wind profiler signal processing

Lehmann

Teschke

2001

Ann. Geophys.

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Abstract. In this paper, we apply wavelet thresholding for removing automatically ground and intermittent clutter (airplane echoes) from wind profiler radar data. Using the concept of discrete multi-resolution analysis and non-parametric estimation theory, we develop wavelet domain thresholding rules, which allow us to identify the coefficients relevant for clutter and to suppress them in order to obtain filtered reconstructions.

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The NIMA Method for Improved Moment Estimation from Doppler Spectra

Cited by 67 publications

References 16 publications

Multi-platform Observations Characterizing the Afternoon-to-Evening Transition of the Planetary Boundary Layer in Northern Alabama, USA

Multi-platform Observations Characterizing the Afternoon-to-Evening Transition of the Planetary Boundary Layer in Northern Alabama, USA

The T1-T2 study: evolution of aerosol properties downwind of Mexico City

Wavelet based methods for improved wind profiler signal processing

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