Multiresolution Flux Decomposition

Howell, Jim; Mahrt, L.

doi:10.1023/a:1000210427798

Cited by 158 publications

(125 citation statements)

References 28 publications

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“…Figure 4 shows the multiresolution spectra of horizontal and vertical velocities at the rooftop and sidewalk sites for 2 days starting from 0000 LST 25 June. The multiresolution spectrum analysis enables the decomposition of non-periodic time series, and the fast Haar transform algorithm used for the multiresolution decomposition requires less computation time than the fast Fourier transform (Howell and Mahrt 1997;Vickers and Mahrt 2003). occurred after 1500−1600 LST throughout the whole period.…”

Section: Measurement Sites and Weather Synopsismentioning

confidence: 99%

Measurements of Turbulent Flow and Ozone at Rooftop and Sidewalk Sites in a High-Rise Building Area

Park¹,

Kwak²,

Han³

et al. 2015

SOLA

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Turbulent flow and ozone concentration at two (rooftop and sidewalk) sites in a high-rise building area of Seoul, Republic of Korea, were measured for the period of 24−27 June 2013 to examine their characteristics according to site location. During the observation period, the diurnal variations of air temperature, wind speed, and turbulent kinetic energy were distinct at both sites. The time series of ozone concentration exhibits a diurnal variation with daytime double peaks and one nighttime peak at both sites. The horizontal wind direction at the rooftop site has variations related to local winds, while the horizontal wind direction at the sidewalk site is mostly southerly (following a nearby street). The multiresolution spectra of horizontal and vertical velocities at the rooftop site confirm diurnal and turbulence-related variations. A quadrant analysis indicates that turbulence at the rooftop site is characterized by frequent ejections and less frequent but stronger sweeps, while turbulence at the sidewalk site is weaker and less characterizable than turbulence at the rooftop site.

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Section: Measurement Sites and Weather Synopsismentioning

confidence: 99%

Measurements of Turbulent Flow and Ozone at Rooftop and Sidewalk Sites in a High-Rise Building Area

Park¹,

Kwak²,

Han³

et al. 2015

SOLA

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“…Spectra and co-spectra for the indicated variables from 70 daytime 30 min periods (for the 25% of periods with the highest aerosol concentrations during BEARPEX). The variances and covariances (and their normalized values) that are presented on the Yaxes were calculated using the multiresolution decomposition methods described by Howell and Mahrt (1997) and Vickers and Mahrt (2003).…”

Section: Spectra and Co-spectramentioning

confidence: 99%

Size-dependent aerosol deposition velocities during BEARPEX'07

Vong

Vickers

et al. 2010

Atmos. Chem. Phys.

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Abstract. Aerosol concentrations and 3-D winds were measured from 9 to 25 September 2007, above a pine forest in California. The measurements were combined using the eddy covariance (EC) technique to determine aerosol eddy fluxes as a function of particle diameter within the accumulation mode size range (0.25 µm≤D p ≤1 µm here). Measured heat and water vapor fluxes were utilized to correct the aerosol eddy fluxes for aerosol hygroscopic growth. The hygroscopic growth correction was necessary despite the low RH and relatively hygrophobic nature of the particles. Uncertainties associated with particle counting also were evaluated from the data. Aerosol deposition velocities (V d = EC turbulent flux/mean particle concentration) during daytime were shown to vary from −0.2 to −1.0 cm s −1 ; the magnitude of particle V d increases with friction velocity and particle diameter.

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“…Since the structures in the time series are generally local and not periodic, we orthogonally decompose the flow into the local multiresolution basis set (e.g., Howell and Mahrt 1997). Fourier decomposition into sinusoidal functions is most suitable for periodic phenomena such as monotonic gravity wave trains while events such as individual microfronts and solitions are more appropriately represented by local basis sets.…”

Section: Decomposition In Timementioning

confidence: 99%

Characteristics of Submeso Winds in the Stable Boundary Layer

Mahrt

2008

Boundary-Layer Meteorol

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The characteristics of submeso motions in the stable boundary layer are examined using observations from networks of sonic anemometers with network sizes ranging from a few hundred metres to 100 km. This study examines variations on time scales between 1 min and 1 h. The analysis focuses on the behaviour of the spectra of the horizontal kinetic energy, the ratios of the three velocity variances, their kurtosis, the dependence of horizontal variability on time scale, and the inter-relationship between vertical vorticity, horizontal divergence and deformation. Motions on larger time and space scales in the stable boundary layer are found to be nearly two-dimensional horizontal modes although the ratio of the vorticity to the divergence is generally on the order of one and independent of scale. One exception is a small network where stronger horizontal divergence is forced by a decrease in surface roughness. The horizontal variability, averaged over 1 h, appears to be strongly influenced by surface heterogeneity and increases with wind speed. In contrast, the time dependence of the horizontal structure on time scales less than one hour tends to be independent of wind speed for the present datasets. The spectra of the horizontal kinetic energy and the ratio of the crosswind velocity variance to the along-wind variance vary substantially between networks. This study was unable to isolate the cause of such differences. As a result, the basic behaviour of the submeso motions in the stable boundary layer cannot be generalized into a universal theory, at least not from existing data.

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Multiresolution Flux Decomposition

Cited by 158 publications

References 28 publications

Measurements of Turbulent Flow and Ozone at Rooftop and Sidewalk Sites in a High-Rise Building Area

Measurements of Turbulent Flow and Ozone at Rooftop and Sidewalk Sites in a High-Rise Building Area

Size-dependent aerosol deposition velocities during BEARPEX'07

Characteristics of Submeso Winds in the Stable Boundary Layer

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