A Study Of Coherent Structures In The Atmospheric Surface Layer Over Short And Tall Grass

Sadani, L. K.; Kulkarni, J. R.

doi:10.1023/a:1018992529079

Cited by 8 publications

(3 citation statements)

References 16 publications

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“…Dataset length Stratification Antonia and Chambers (1978) 1.5 h Stable Gao et al (1989) 1.5 h Unstable Bergström and Högström (1989) 200 min Unstable Paw U et al (1992) Not noted Unstable, neutral, stable Gao et al (1992) 23 h Unstable, neutral, stable Gao et al (1993) 30 min Unstable Lu and Fitzjarrald (1994) 85 h Unstable, stable Qiu et al (1995) 35 h Unstable Chen et al (1997) 65 h Unstable Brunet and Irvine (2000) 350 h Unstable, neutral, stable Sadani and Kulkarni (2001) 2 days Unstable Krusche and De Oliveira (2004) 43 h Unstable Feigenwinter and Vogt (2005) 7 h (116 events) Unstable Thomas and Foken (2006) Up to 1,650 h Unstable, neutral, stable control and partitioning of the data into three wind sectors, only 282-462.5 h of temperature fluctuation data remained for individual wind sectors. The present paper addresses the above mentioned limitations by applying an objective and well-adapted methodology for coherent structure extraction.…”

Section: Authormentioning

confidence: 99%

Long-term study of coherent structures in the atmospheric surface layer

Barthlott

Drobinski

Fesquet

et al. 2007

Boundary-Layer Meteorol

119

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A long-term study of coherent turbulence structures in the atmospheric surface layer has been carried out using 10 months of turbulence data taken on a 30-m tower under varying meteorological conditions. We use an objective detection technique based on wavelet transforms. The applied technique permits the isolation of the coherent structures from small-scale background fluctuations which is necessary for the development of dynamical models describing the evolution and properties of these phenomena. It was observed that coherent structures occupied 36% of the total time with mean turbulent flux contributions of 44% for momentum and 48% for heat. The calculation of a transport efficiency parameter indicates that coherent structures transport heat more efficiently than momentum. Furthermore, the transport efficiency increases with increasing contribution of the structures to the overall transport

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Section: Authormentioning

confidence: 99%

Long-term study of coherent structures in the atmospheric surface layer

Barthlott

Drobinski

Fesquet

et al. 2007

Boundary-Layer Meteorol

119

View full text Add to dashboard Cite

show abstract

“…These organized motions have been shown to be responsible for the production of turbulence and to contain the majority of the turbulent kinetic energy (TKE) in the ABL (e.g., Etling and Brown 1993;Wilson 1996;Wilson and Wyngaard 1996;Sadani and Kulkarni 2001;Katul et al 2006). Quantitative models utilizing structural information of these motions to predict either statistical profiles (e.g., Townsend 1976;Perry et al 1986) or turbulent dynamics (e.g., Aubry et al 1988;Rempfer and Fasel 1994;Waleffe 1997) have shown encouraging results.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Coherent Structures Within the Atmospheric Boundary Layer

Huang

Cassiani

Albertson

2009

Boundary-Layer Meteorol

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Large-eddy simulation has become an important tool for the study of the atmospheric boundary layer. However, since large-eddy simulation does not simulate small scales, which do interact to some degree with large scales, and does not explicitly resolve the viscous sublayer, it is reasonable to ask if these limitations affect significantly the ability of large-eddy simulation to simulate large-scale coherent structures. This issue is investigated here through the analysis of simulated coherent structures with the proper orthogonal decomposition technique. We compare large-eddy simulation of the atmospheric boundary layer with direct numerical simulation of channel flow. Despite the differences of the two flow types it is expected that the atmospheric boundary layer should exhibit similar structures as those in the channel flow, since these large-scale coherent structures arise from the same primary instability generated by the interaction of the mean flow with the wall surface in both flows. It is shown here that several important similarities are present in the two simulations: (i) coherent structures in the spanwise-vertical plane consist of a strong ejection between a pair of counter-rotating vortices; (ii) each vortex in the pair is inclined from the wall in the spanwise direction with a tilt angle of approximately 45 • ; (iii) the vortex pair curves up in the streamwise direction. Overall, this comparison adds further confidence in the ability of large-eddy simulation to produce large-scale structures even when wall models are used. Truncated reconstruction of instantaneous turbulent fields is carried out, testing the ability of the proper orthogonal decomposition technique to approximate the original turbulent field 123 148 J. Huang et al.with only a few of the most important eigenmodes. It is observed that the proper orthogonal decomposition reconstructs the turbulent kinetic energy more efficiently than the vorticity.

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“…In the tropics, significant diurnal oscillations in wind speed (WS), static instability, turbulent exchange and convective activity are observed within the atmospheric boundary layer (Asnanai, 1993). Some of the significant field experimental studies from the tropical Indian region include the Monsoon Experiment (MONEX) during 1979 (Das et al , 2004), monsoon boundary layer Experiment (MONTBLEX–1990) conducted during the southwest summer monsoon season over the monsoon trough region of the Gangetic plains (Goel and Srivastava, 1990; Kusuma et al , 1991, 1995, 1996; Sivaramakrishnan et al , 1992; Kailas and Goel, 1996) and Land Surface Process Experiment (LASPEX–1997) conducted over the Sabarmati basin of Gujarat (Pillai et al , 1998; Satyanarayana et al , 2000; Nagar et al , 2001; Sadani and Kulkarni, 2001). On the east coast, surface and boundary layer measurements were made with meteorological towers, tethered balloons and a Doppler SODAR at Kalpakkam to study the characteristics of internal boundary layer (Venkatesan et al , 1999) for understanding atmospheric diffusion at the tropical costal region.…”

Section: Introductionmentioning

confidence: 99%