BLLAST Modelling activities


The BLLAST project has a strong modeling component to complete the investigation of the dynamics of the afternoon transition and support the observations taken during the observational period.

The modelling tools:

Up to now the modeling tools available in BLLAST community are:


Research strategy

We plan before, during and after the BLLAST experimental campaign a number of numerical experiments at different spatial and time scales. These are the following:


Scientific questions:

This section lists the different scientific questions the modeling group will try to answer.


A/ The common questions we should address before a LES study:

1/ How LES models simulate the transition period?

2/ Can we provide some guidance for the field campaign what to look (which variables)? Where (which levels)? When?

3/ At what time the LES should start to correctly simulate the transition period from the atmospheric turbulence and surface point of view?

4/ Is the response very sensitive to resolution, numerical schemes and sub-grid scale parameterizations?

5/ How do operational models perform in describing the transition? This can help focusing on the major defaults of those models. Focusing in the physical parameterizations: boundary layer schemes, surface representations and radiation.


B/ The atmospheric boundary layer specific questions

1/vertical structure:

2/ timing:

3/ role of different processes:


C/ Surface processes

1/ What is the impact of the surface characteristics on the transition period?

2/ What are the relevant surface parameters for the scaling: heat storage in the cover/ground, Bowen ratio, roughness , ...

3/ Over heterogeneous surface

4/ Impact on in situ measurements:

5/ Over topography:

What is the impact of the topography on the transition?

6/ Can we suggest an appropriate scaling which would cover this transition from the well-mixed BL to the stable BL and overlying residual layer ?

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