Estimations from geostrophic trajectories of horizontal diffusivity in the mid‐latitude troposphere and lower stratosphere

Murgatroyd, R. J.

doi:10.1002/qj.49709540304

Cited by 52 publications

(29 citation statements)

References 8 publications

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“…Their main result was that horizontal EAFs provide evidence for the presence of a negative lobe, attributed to the meander, which did not appear in the vertical component. Negative lobes in EAFs were also reported by Frenkiel (1953), Kao (1965), Murgatroyd (1969), Csanady (1973), Hanna (1983) and Maryon (1998). In particular, Hanna (1983, Figure 4) reported an example of a longitudinal wind component EAF experiencing a large negative lobe, reaching a minimum of )0.65 and a secondary maximum of 0.40.…”

Section: Introductionmentioning

confidence: 67%

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An Analysis Of Sonic Anemometer Observations In Low Wind Speed Conditions

Anfossi

Oettl

Degrazia

et al. 2005

Boundary-Layer Meteorology

169

184

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When the wind speed decreases below a certain value (1-2 m s À1 ) meandering (low frequency horizontal wind oscillations) starts to prevail. In these conditions it becomes difficult to define a precise mean wind direction and to estimate the airborne dispersion. To study the wind and turbulence characteristics during meandering, two sonic anemometer datasets, containing hourly wind observations, were analysed: the first one, lasting 1 year, was recorded in complex terrain (Graz, Austria) and the second one, lasting about 1 month, was recorded in a rather flat area (Tisby, Sweden). It was found that meandering seems to exist under all meteorological conditions regardless of the stability or wind speed and it was confirmed that meandering sets a lower limit for the horizontal wind component variances. Further, it was found that the autocorrelation functions of the horizontal wind components, computed for the low wind cases, show an oscillating behaviour with the presence of large negative lobes. Two different relationships from the literature, and relevant to these oscillatory aspects, were fitted to the data. They contain two parameters: one associated and relevant to the classical integral time scale and the second with meandering occurrence. Based on these relationships, expressions for the mean square displacement of particles r 2 y ðtÞ were also derived.

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Section: Introductionmentioning

confidence: 67%

“…was also proposed by Murgatroyd (1969). In contrast to Equation (7), Equations (9), (10) and (11) depend upon two parameters.…”

Section: Analytical Forms For Low Wind Eafmentioning

confidence: 92%

An Analysis Of Sonic Anemometer Observations In Low Wind Speed Conditions

Anfossi

Oettl

Degrazia

et al. 2005

Boundary-Layer Meteorology

169

184

View full text Add to dashboard Cite

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“…The diffusion term includes both vertical and horizontal diffusion. Horizontal diffusion is set proportional to the variance of the horizontal wind components (Murgatroyd, 1969). Vertical diffusion in the boundary layer is specified as a function of the large-scale vertical temperature gradient (Oort, 1983) and surface roughness.…”

Section: Model Descriptionmentioning

confidence: 99%

A global three-dimensional model of the tropospheric sulfur cycle

1991

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The tropospheric part of the atmospheric sulfur cycle has been simulated in a global threedimensional model. The model treats the emission, transport, chemistry, and removal processes for three sulfur components; DMS (dimethyl sulfide), SO, and SO% (sulfate). These processes are resolved using an Eulerian transport model, the MOGUNTIA model, with a horizontal resolution of 10 longitude by 10" latitude and with 10 layers in the vertical between the surface and 100 hPa. Advection takes place by climatological monthly mean winds. Transport processes occurring on smaller space and time scales are parameterized as eddy diffusion except for transport in deep convective clouds which is treated separately. The simulations are broadly consistent with observations of concentrations in air and precipitation in and over polluted regions in Europe and North America. Oxidation of DMS by OH radicals together with a global emission of 16 Tg DMS-S yr-' from the oceans result in DMS concentrations consistent with observations in the marine boundary layer. The average turn-over times were estimated to be 3, 1.2-1.8, and 3.2-6.1 days for DMS, SO,, and SOi-respectively.

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“…On the other hand, air masses in the jet core are usually moist, indicating a tropospheric origin. Murgatroyd [14] finds that the water content and ozone measurement in the jet stream indicate that these often appear to be descending motions on the low pressure side of the middle latitude jet stream through the tropopause gap. A tongue of dry, ozone-rich air then appears to flow downwards below the jet stream, often in the upper region of a front.…”

Section: Total ( Unbrack Eted Figures) and Cumulative (Bracketed Figumentioning

confidence: 98%

Some features of the ozone climatology of Ontario, Canada and possible contributions of stratospheric ozone to surface concentrations

Mukammal

Neuman

Nichols

1985

Arch. Met. Geoph. Biocl. A.

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SummaryBackground ozone concentration displayed distinct seasonal variations at all stations, with a maximum of about 40 ppb in spring and a minimum of about 23 ppb in autumn. The monthly and yearly mean diurnal variations of ozone at urban stations exhibited bi-modal characteristics not evident at rural sites. Two daily maxima and minima were recorded at urban stations, but only one maximum and one minimum at rural sites. The second minimum in the evening at urban stations was shown to be related to high levels of nitric oxide, while nighttime heat island was considered the main cause of the second maximum. One-day resultant trajectories show that the most frequent and highest ozone concentrations were associated with a relatively light to moderate south to southwesterly flow but not with light or with strong winds. Although there were several recognizable meteorological regimes associated with elevated ozone concentrations over Ontario, those with weak pressure gradients favourable for the onset of lake breeze or with southwesterly flows on the west side of slow-moving high pressure centres crossing the eastern United States were the most frequent and resulted in the highest ozone concentrations. Ozone maxima over Ontario may mostly be attributed to long distance transport of emissions from major industrial areas south of the border. However, tropospheric and stratospheric contributions cannot be ruled out and may even be a major source at times. A case study of possible stratospheric ozone influx into the troposphere is presented. Zusammenfassung Grundlagen der Ozonklimatologie der

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Estimations from geostrophic trajectories of horizontal diffusivity in the mid‐latitude troposphere and lower stratosphere

Cited by 52 publications

References 8 publications

An Analysis Of Sonic Anemometer Observations In Low Wind Speed Conditions

An Analysis Of Sonic Anemometer Observations In Low Wind Speed Conditions

A global three-dimensional model of the tropospheric sulfur cycle

Some features of the ozone climatology of Ontario, Canada and possible contributions of stratospheric ozone to surface concentrations

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