Roughness sublayer and canopy layer turbulent profiles over tall vegetation
This presentation is the property of its rightful owner.
Sponsored Links
1 / 25

Roughness Sublayer and Canopy Layer turbulent profiles over tall vegetation PowerPoint PPT Presentation


  • 194 Views
  • Uploaded on
  • Presentation posted in: General

Roughness Sublayer and Canopy Layer turbulent profiles over tall vegetation. Ricardo K. Sakai D. R. Fitzjarrald Matt Czikowsky University at Albany, SUNY. Surface Layer. Inertial sublayer. Cross section from Laser Vegetation Imaging Sensor (LVIS). Constant Flux. Roughness sublayer.

Download Presentation

Roughness Sublayer and Canopy Layer turbulent profiles over tall vegetation

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Roughness Sublayer and Canopy Layer turbulent profiles over tall vegetation

Ricardo K. Sakai

D. R. Fitzjarrald

Matt Czikowsky

University at Albany, SUNY


Surface layer

Surface Layer

Inertial sublayer

Cross section from Laser Vegetation Imaging Sensor (LVIS)

Constant Flux

Roughness

sublayer

Rugosity = f(canopy topography)

Jess Parker

Canopy

sublayer


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Wind Tunnel

cylinders

HF Foliated

Deciduous

HF Leafless

Deciduous

Boreal forest

Coniferous

Oak Ridge

deciduos

Amazon

Broad Leaf

Almond orchard

Camp Borden

Deciduous

Canopy area densities (CAD, , where PAI is the plant area index) for (a) for wind tunnel (Raupach et al., 1986), (b) HF foliated (Parker, personal communication), (c) HF leafless (Parker, personal communication), (d) coniferous forest (Halldin, 1985), (e) Amazon forest (Roberts et al., 1994) (f) Oak Ridge (Meyers and Baldocchi, 1991), (g) almond orchard (Baldocchi and Hutchison, 1988), (h) Camp Borden (Neumann et al., 1989).


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

CANOPY LAYER


Normalized cumulative canopy area density

Normalized cumulative canopy area density:

where h is the mean canopy height.

PAI is plant area index

CAD is the canopy area distribution


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

σw /u*vsz/h

σw /u*vszc

MOS value in IL


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

σU /u*vsz/h

σU /u*vszc

MOS value in IL


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

u*(z/h)/u*(1) vsz/h

u*(z/h)/u*(1) vszc


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Roughness Sublayer


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

For a broad leaf forests:

Displacement height (d) - mean level of momentum absorption (Thom, 1971):

Traditional:New approach:

Therefore: dc=0.7 h (Deciduous - Broad leaf forests)

dc=0.6 h (sparse coniferous) - numerically


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

σwvsz/h

σwvs (z-dc)/(h-dc)

MOS value in the IL


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Skw(w) vsz/h

Skw(w) vs (z –dc)/(h-dc)

Skewness

Skewness

Skewness in the lower CBL


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Fitted curve (above canopy):


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Spectral Analysis

Drowning in spectra, craving cospectra


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Cospectral shape in RSL:

-5/3 power law

Su

Less peaked

More peaked

Moraes et al., accepted in Physica A


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Dimensionless frequency:

Where:

Above canopy: z > h → z’= z-dc

Inside canopy: z < h → z’= h-dc


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

Conclusions:

Seeking similarity rules for tall canopies.

Scaling length is (h-dc(CAD)) in the RSL for several forests

Canopy Layer (several forests):

- The use of the canopy area density helps to differentiate broad leaves from coniferous forests, approaching to a more “universal relationship”.

To improve, rugosity?

Roughness sublayer (several forests):

- Ratio [(z-dc)/(h- dc)] is about 2.4 to 3.5

- Scaling to (z-d)/(h-d) gives better generalization.

- Skewness of w profile is a good indicator of the RSL

Spectral analysis (only HF):

- best scaling is (h-dc) within the canopy.

- “Short circuit”/wake effect only during the foliated period


Roughness sublayer and canopy layer turbulent profiles over tall vegetation

[previous][next]

Gryanik and Hartmann,2002,JAS

Fig. 4. (a), (c) Skewness of the vertical wind velocity and (b), (d) the temperature. (a) and (b) Full dots represent the Reynolds-averaged skewness and open circles the mass-flux skewness [Eq. (10)] of the aircraft data. Solid lines are the LES results of free convection of MGMOW. The ordinates show normalized height. (c), (d) Mass-flux vs Reynolds skewness of the aircraft data. The ratio of the mass-flux to Reynolds skewness is 0.30 for Sθ and 0.31 for Sw, but the correlation is very low. De Laat and Duynkerke (1998) found a ratio of 0.25 for Sw for a stratocumulus case


  • Login