Nesting Overview#

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PALM offers two different kinds of nesting.

• self-nesting
  One or more instances of PALM (so called children or childs) with higher spatial resolution are nested inside the total domain (called the root domain). Recursive nesting (nests within nests) is allowed. A typical application for self-nesting is if high spatial resolution is only required at specific areas of interest, e.g. within the urban canopy layer or in the entrainment zone at the top of a mixed layer, and if computational resources do not allow to use that high resolution for the total tomain.
  
  
• mesoscale nesting
  Boundary layer processes contain a wide range of scales, ranging from the mesoscale, e.g. urban heat island, land-sea breeze, low-level jets, etc. down to the microscale, e.g. effects of single trees, building and roof shapes, local emissions, etc.. To consider both large model domains and a small grid size would often require huge computational resources. The idea of mesoscale nesting is to consider the effects of mesoscale processes in PALM via lateral (and top) boundary conditions provided by larger-scale models, and refine the grid within the domain of interest.

Mesoscale nesting and self-nesting can be used simultaneously. In a self-nesting setup, mesocale-nesting can be used for the root domain (but only for the root domain!).