Further LES-study on the energy imbalance problem with eddy covariance fluxes
Responsible: Gerald Steinfeld
Project type: ​DAAD grant and Academic Frontiers Student Exchange Promotion Program In 2003-2004 (​MEXT, Japan)
Duration: 01/06/2003 - 31/05/2004

This is a joint project together with Manabu Kanda at the ​Department of International Development Engineering, Tokyo Institute of Technology, Japan. It includes a one-year research stay in Japan.

This study is based on the former co-operation between Kanda and Marcus Letzel - LES Study of the Energy Imbalance Problem with Eddy Covariance Fluxes. In their study they carried out simulations of a convective boundary layer with the following prerequisites:

• horizontal homogenous surface heat flux (or a mere 1D horizontal variation)
  
• vanishing horizontal mean value of the vertical velocity.
  
  

In the scope of this project it should be investigated what the effects are on the observed energy imbalance if at least one of these "ideal case" prerequisites does not apply. For example, the presence of inhomogenities is characteristic of the Earth´s surface.

Therefore it is planned to carry out simulations with a prescribed one-dimensional sinusoidal surface heat flux (parameter studies with e.g. varying maximum amplitude and wavelength) in order to study the effects of the thermally induced meso-scale circulation on the observed energy imbalance characteristics. These studies imply a slightly different definition of energy imbalance compared with the former studies of Kanda et al.?

Furthermore the influence of a synoptic-scale downward movement - as it is observed in high pressure systems - on the energy imbalance should be investigated by a LES-study. The goal is to examine the results of some theoretical studies.

Finally, some fundamental comparisons between the heat fluxes calculated by the temporal eddy covariance method and calculated the spatial eddy covariance method will be carried out.