Clear-Air Roll Vortices and Turbulent Motions as Detected with an Airborne Gust Probe and Dual-Doppler Radar

Reinking, Roger F.; Doviak, Richard J.; Gilmer, R. O.

doi:10.1175/1520-0450(1981)020<0678:carvat>2.0.co;2

Cited by 40 publications

(25 citation statements)

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“…These streets, which usually arise in moderate or strong winds in conditions with a significant upward heat flux (Le Mone, 1973), have been shown to be associated with large-scale longitudinal roll motions in the PBL. They have also been detected in clear air (Reinking et al, 1981) and the presence of clouds is regarded as a consequence rather than a cause of the roll motions.…”

Section: Introductionsupporting

confidence: 93%

A numerical study of cloud streets in the planetary boundary layer

Mason

1985

Boundary-Layer Meteorol

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A two-dimensional numerical model is used to study the influence of small non-precipitating clouds on horizontal roll vortices in the planetary boundary layer. The model explicitly represents the large-scale two-dimensional motions whilst small-scale eddies are parameterized by a buoyancy dependent mixing-length hypothesis. It is applied to conditions corresponding to an observed case of cloud street formation.

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Section: Introductionsupporting

confidence: 93%

A numerical study of cloud streets in the planetary boundary layer

Mason

1985

Boundary-Layer Meteorol

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“…The results also suggest that the importance of roll vortices in transporting sensible heat and moisture increases upward, and that these transports near Zi are primarily carried out by roll circulations in the roll vortex regime (Figures 11 and 14). These results are in good agreement with previous studies (e.g., LeMone, 1973, Reinking et al, 1981CZ).…”

Section: Discussionmentioning

confidence: 99%

“…As can be seen from Figure 10, all three normalized spectra have higher spectral densities in the frequency band f = 0.2-0.5 and peak at the frequencies near f = 0.33. This result indicates that the roll spacing is about three times the MABL depth, in good agreement with previous studies (e.g., LeMone, 1973;Reinking et al, 1981).…”

Section: Spectral Distributionsmentioning

confidence: 99%

Heat fluxes and roll circulations over the western Gulf Stream during an intense cold-air outbreak

Chou

Ferguson

1991

Boundary-Layer Meteorol

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Turbulence and heat fluxes in the marine atmospheric boundary layer (MABL) far the roll vortex regime, observed during the Genesis of Atlantic Lows Experiment (GALE) over the western Gulf Stream, have been studied. The spqctral analysis suggests that cloud streets (roll vortices) are vertically organized convection in the MABL having the same roll scale for both the cloud layer and subcloud layer, and that the roll spacing is about three times the MABL depth. The roll circu~tions contribute signi~cantly to the sensible (temperature) and latent heat (moisture) fluxes with importance increasing upward. Near the MABL top, these fluxes are primarily due to roll vortices which transfer both sensible heat and moisture upward in the lower half of the convective MABL. Near the MABL top, the roll circulations transfer sensible heat downward and moisture upward in the clear thermalstreet region, but roll vortices influenced by evaporative cooling can transfer sensible heat upward and moisture downward in the cloud-street region. Near the cloud-top, the upward buoyancy Rux due to evaporative cooling is highly related to the roll circulations near the inversion.For the lower half of the MABL, the normalized temperature flux decreases upward more rapidly than the humidity flux, which is mainly because Potential temperature (8) increases slightly upward while humidity (q) decreases slightly upward above the unstable surface layer. The gradient production (associated with the 6 gradient) is a source for the temperature flux in the unstable surface layer but changes to a sink in the mixed layer, while the gradient production (associated with the q gradient) acts as a source for the humidity ilux in both the unstable surface and mixed layers. The results suggest that the entrainment at the MABL top might affect the budgets of temperature and humidity fluxes in the lower MABL, but not in the unstable surface layer.

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“…Dual-Doppler wind analysis methods have greatly aided our understanding of weather phenomena ranging from mesoscale convective complexes to clear air boundary layers (e.g., Browning and Wexler 1968;Brandes 1977;Ray et al 1981;Reinking et al 1981;Carbone 1983;Kessinger et al 1987;Parsons and Kropfli 1990;Atkins et al 1995;Dowell and Bluestein 1997;Sun andCrook 1997, 1998). However, most of these methods still suffer from notable deficiencies, including the setting of often-arbitrary vertical velocity boundary conditions, spatial interpolation and discretization errors, uncertainties in radial wind estimates (due to, e.g., sidelobes and ground clutter), and the nonsimultaneous nature of the measurements.…”

Section: Introductionmentioning

confidence: 67%

A Three-Dimensional Variational Data Analysis Method with Recursive Filter for Doppler Radars

Gao

Xue

Brewster

et al. 2004

J. Atmos. Oceanic Technol.

214

212

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In this paper, a new method of dual-Doppler radar wind analysis based on a three-dimensional variational data assimilation (3DVAR) approach is proposed. In it, a cost function, including background term and radial observation term, is minimized through a limited memory, quasi-Newton conjugate-gradient algorithm with the mass continuity equation imposed as a weak constraint. In the method, the background error covariance matrix, though simple in this case, is modeled by a recursive filter. Furthermore, the square root of this matrix is used to precondition the minimization problem.The current method is applied to Doppler radar observation of a supercell storm, and the analysis results are compared to a conceptual model and previous research. It is shown that the horizontal circulations, both within and around the storms, as well as the strong updraft and the associated downdraft, are well analyzed. Because no explicit integration of the anelastic mass continuity equation is involved, error accumulation associated with such integration is avoided. As a result, the method is less sensitive to the vertical boundary uncertainties.

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Clear-Air Roll Vortices and Turbulent Motions as Detected with an Airborne Gust Probe and Dual-Doppler Radar

Cited by 40 publications

References 0 publications

A numerical study of cloud streets in the planetary boundary layer

A numerical study of cloud streets in the planetary boundary layer

Heat fluxes and roll circulations over the western Gulf Stream during an intense cold-air outbreak

A Three-Dimensional Variational Data Analysis Method with Recursive Filter for Doppler Radars

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