scholarly journals On the role of infiltration and exfiltration in swash zone boundary layer dynamics

2015 ◽  
Vol 120 (9) ◽  
pp. 6329-6350 ◽  
Author(s):  
José Carlos Pintado‐Patiño ◽  
Alec Torres‐Freyermuth ◽  
Jack A. Puleo ◽  
Dubravka Pokrajac
Keyword(s):  
Boundary Layer ◽  
Swash Zone ◽  
Zone Boundary ◽  
Boundary Layer Dynamics

scholarly journals Surface heterogeneity impacts on boundary layer dynamics via energy balance partitioning

2010 ◽  
Vol 10 (7) ◽  
pp. 17815-17851 ◽  
Author(s):  
N. A. Brunsell ◽  
D. B. Mechem ◽  
M. C. Anderson
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Land Surface ◽  
Surface Heterogeneity ◽  
Length Scales ◽  
Surface Conditions ◽  
Boundary Layer Dynamics

Abstract. The role of land-atmosphere interactions under heterogeneous surface conditions is investigated in order to identify mechanisms responsible for altering surface heat and moisture fluxes. Twelve coupled land surface – large eddy simulation scenarios with four different length scales of surface variability under three different horizontal wind speeds are used in the analysis. The base case uses Landsat ETM imagery over the Cloud Land Surface Interaction Campaign (CLASIC) field site for 3 June 2007. Using wavelets, the surface fields are band-pass filtered in order to maintain the spatial mean and variances to length scales of 200 m, 1600 m, and 12.8 km as lower boundary conditions to the model. The simulations exhibit little variation in net radiation. Rather, a change in the partitioning of the surface energy between sensible and latent heat flux is responsible for differences in boundary layer dynamics. The sensible heat flux is dominant for intermediate surface length scales. For smaller and larger scales of surface heterogeneity, which can be viewed as being more homogeneous, the latent heat flux becomes increasingly important. The results reflect a general decrease of the Bowen ratio as the surface conditions transition from heterogeneous to homogeneous. Air temperature is less sensitive to surface heterogeneity than water vapor, which implies that the role of surface heterogeneity in modifying the local temperature gradients in order to maximize convective heat fluxes. More homogeneous surface conditions, on the other hand, tend to maximize latent heat flux. Scalar vertical profiles respond predictably to the partitioning of surface energy. Fourier spectra of the vertical wind speed, air temperature and specific humidity (w, T and q) and associated cospectra (w'T', w'q' and T'q'), however, are insensitive to the length scale of surface heterogeneity, but the near surface spectra are sensitive to the mean wind speed.

scholarly journals Boundary layer dynamics in the swash zone under large-scale laboratory conditions

2016 ◽  
Vol 113 ◽  
pp. 47-61 ◽  
Author(s):  
Andrea Ruju ◽  
Daniel Conley ◽  
Gerd Masselink ◽  
Martin Austin ◽  
Jack Puleo ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Swash Zone ◽  
Laboratory Conditions ◽  
Boundary Layer Dynamics

scholarly journals The role of boundary layer dynamics on the diurnal evolution of isoprene and the hydroxyl radical over tropical forests

2011 ◽  
Vol 116 (D7) ◽  
Author(s):  
Jordi Vilà-Guerau de Arellano ◽  
Edward G. Patton ◽  
Thomas Karl ◽  
Kees van den Dries ◽  
Mary C. Barth ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hydroxyl Radical ◽  
Tropical Forests ◽  
Boundary Layer Dynamics

scholarly journals Turbulent transport of energy across a forest and a semiarid shrubland

2018 ◽  
Vol 18 (13) ◽  
pp. 10025-10038 ◽  
Author(s):  
Tirtha Banerjee ◽  
Peter Brugger ◽  
Frederik De Roo ◽  
Konstantin Kröniger ◽  
Dan Yakir ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Turbulent Transport ◽  
Surface Heterogeneity ◽  
Flux Divergence ◽  
Diurnal Cycles ◽  
Turbulent Statistics ◽  
Secondary Circulations ◽  
The Difference ◽  
Boundary Layer Dynamics

Abstract. The role of secondary circulations has recently been studied in the context of well-defined surface heterogeneity in a semiarid ecosystem where it was found that energy balance closure over a desert–forest system and the structure of the boundary layer was impacted by advection and flux divergence. As a part of the CliFF (“Climate feedbacks and benefits of semi-arid forests”, a collaboration between KIT, Germany, and the Weizmann Institute, Israel) campaign, we studied the boundary layer dynamics and turbulent transport of energy corresponding to this effect in Yatir Forest situated in the Negev Desert in Israel. The forest surrounded by small shrubs presents a distinct feature of surface heterogeneity, allowing us to study the differences between their interactions with the atmosphere above by conducting measurements with two eddy covariance (EC) stations and two Doppler lidars. As expected, the turbulence intensity and vertical fluxes of momentum and sensible heat are found to be higher above the forest compared to the shrubland. Turbulent statistics indicative of nonlocal motions are also found to differ over the forest and shrubland and also display a strong diurnal cycle. The production of turbulent kinetic energy (TKE) over the forest is strongly mechanical, while buoyancy effects generate most of the TKE over the shrubland. Overall TKE production is much higher above the forest compared to the shrubland. The forest is also found to be more efficient in dissipating TKE. The TKE budget appears to be balanced on average both for the forest and shrubland, although the imbalance of the TKE budget, which includes the role of TKE transport, is found to be quite different in terms of diurnal cycles for the forest and shrubland. The difference in turbulent quantities and the relationships between the components of TKE budget are used to infer the characteristics of the turbulent transport of energy between the desert and the forest.

scholarly journals Scattering and absorption properties of near-surface aerosol over Gangetic–Himalayan region: the role of boundary layer dynamics and long-range transport

2014 ◽  
Vol 14 (15) ◽  
pp. 21101-21148 ◽  
Author(s):  
U. C. Dumka ◽  
D. G. Kaskaoutis ◽  
M. K. Srivastava ◽  
P. C. S. Devara
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
Long Range Transport ◽  
Monsoon Circulation ◽  
Anthropogenic Aerosols ◽  
Absorption Properties ◽  
Near Surface ◽  
Range Transport ◽  
Boundary Layer Dynamics

Abstract. Knowledge of light scattering and absorption properties of atmospheric aerosols is of vital importance in evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic–Himalayan (GH) region due to large aerosol loading over the plains and the uplift over the Himalayan range causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, Ganges Valley Aerosol Experiment (GVAX) was initiated over the region aiming to examine the aerosol properties, source regions, uplift mechanisms and aerosol-cloud interactions. The present study examines the temporal (monthly, seasonal) evolution of scattering (σsp) and absorption (σap) coefficients, their wavelength dependence, and the role of the Indo-Gangetic plains (IGP), boundary-layer dynamics (BLD) and long-range transport (LRT) in the aerosol uplift over the Himalayas. The measurements are performed at the elevated site Nainital via the Atmospheric Radiation Measurement Mobile Facility including several instruments (Nephelometer, Particle Soot Absorption Photometer, etc.) during June 2011 to March 2012. The σsp and σap exhibit a pronounced seasonal variation with monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during monsoon, in contrast to the absorption Ångström exponent which maximizes in December–March. The analysis is performed separately for particles bellow 10 and 1μm in diameter in order to examine the influence of the particle size on optical properties. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes, while the aerosols are found to be well-mixed and aged-type dominant.

scholarly journals Role of the boundary layer dynamics effects on an extreme air pollution event in Paris

2016 ◽  
Vol 141 ◽  
pp. 571-579 ◽  
Author(s):  
J.-C. Dupont ◽  
M. Haeffelin ◽  
J. Badosa ◽  
T. Elias ◽  
O. Favez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Pollution Event ◽  
Boundary Layer Dynamics

Short-Period Modulations in Aerosol Optical Depths over the Central Himalayas: Role of Mesoscale Processes

2008 ◽  
Vol 47 (5) ◽  
pp. 1467-1475 ◽  
Author(s):  
U. C. Dumka ◽  
K. Krishna Moorthy ◽  
S. K. Satheesh ◽  
Ram Sagar ◽  
P. Pant
Keyword(s):  
Boundary Layer ◽  
Arid Regions ◽  
Synoptic Scale ◽  
Wind Fields ◽  
Central Himalayas ◽  
Short Period ◽  
Observational Site ◽  
Boundary Layer Dynamics ◽  
Mesoscale Processes

Abstract Multiyear measurements of spectral aerosol optical depths (AODs) were made at Manora Peak in the central Himalaya Range (29°22′N, 79°27′E, ∼1950 m above mean sea level), using a 10-channel multiwavelength solar radiometer for 605 days during January 2002–December 2004. The AODs at 0.5 μm were very low (≤0.1) in winter and increased steeply to reach high values (∼0.5) in summer. It was observed that monthly mean AODs vary significantly (by more than a factor of 6) from January to June. Strong short-period fluctuations (within a daytime) were observed in the AODs. Further investigations of this aspect have revealed that boundary layer dynamics plays a key role in transporting aerosols from the polluted valley region to higher altitudes, causing large contrast in AODs between forenoon and afternoon. The seasonal variations in AODs, while examined in conjunction with synoptic-scale wind fields, have revealed that the transport of dust aerosols from arid regions to the valley regions adjacent to the observational site and their subsequent transport upward by boundary layer dynamics are responsible for the summer increases.

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