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ECMWF analysis over Atlantic-Africa regions Print E-mail
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ECMWF analysis over Atlantic-Africa regions
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Levels

Model levels

  • 60 levels before 01/02/2006
  • 91 levels after 01/02/2006 included

 

The ECMWF model uses a hybrid vertical coordinate that reduces smoothly from a terrain-following sigma coordinate in the lower troposphere to a pressure coordinate in the stratosphere.


To represent the vertical variation of the dependent variables Chap2_Discretization75.gif , Chap2_Discretization20.gif , Chap2_Discretization25.gif and Chap2_Discretization30.gif , the atmosphere is divided into Chap2_Discretization50.gif layers. These layers are defined by the pressures at the interfaces between them (the `half-levels'), and these pressures are given by

Chap2_Discretization56.gif (1)



for Chap2_Discretization61.gif . The Chap2_Discretization66.gif and Chap2_Discretization71.gif are constants whose values effectively define the vertical coordinate and Chap2_Discretization114.gif is the surface pressure field.


The values of the Chap2_Discretization5.gif and Chap2_Discretization15.gif for all Chap2_Discretization99.gif allow the reconstruction of the `full-level' pressure Chap2_Discretization104.gif associated with each model level (middle of layer) from Chap2_Discretization119.gif (Chap2_Discretization109.gif )by using equation (1) and the surface pressure field.

 

Pressure levels

  • 21 levels (in hPa) : 1000, 925, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10, 7, 5, 3, 2,1

The fields have been interpolated to standard pressure levels from the original model levels.




Last Updated ( Monday, 02 June 2008 )