A Study of Turbulence above the Amazon Forest Using the Reduced TKE Phase Space
Abstract
We propose an approach based on a simplified form of the TKE budget equation (the "reduced TKE budget") which can be represented by a two-dimensional phase space. The phase space provides a visual way to quantify relative contributions of shear and buoyancy production/destruction of TKE, as well as the local imbalance between production and dissipation. We apply this framework to study turbulence in the canopy roughness sublayer above the Amazon forest (using data from the GoAmazon field campaign), and contrast results with those characteristic of the canonical surface layer (using data from the AHATS field campaign). Results reveal interesting insight into the behavior of the vertical velocity variance over forests, linking its magnitude to the imbalance between local production and dissipation of TKE. In addition, the phase space reveals a large number of runs with continuous 3D turbulence and a characteristic K41 inertial subrange for very large flux Richardson numbers (Rif = 1 or larger). Further analysis shows that this turbulence is sustained by turbulent transport of TKE, and a criterion is proposed for the breaking point of sustained K41 turbulence in the presence of transport.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A52D..03C
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSESDE: 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSESDE: 3379 Turbulence;
- ATMOSPHERIC PROCESSES