The above link describes the coefficients used to define the ECMWF model levels in pressure in order to compute geopotential height. Is there a similar data for NCEP reanalysis model or is the data already on pressure levels in which case the above step is not required ? To be precise I am looking for the identical data for the T62 NCEP reanalysis data(2.5 x 2.5). The NCEP reanalysis model uses the sigma vertical coordinate. The same question can be rephrased in the following manner
1) What are the values of the sigma levels and where can they be downloaded? For e.g. if the sigma level is 0.995 and the surface pressure is 1000 hPa then the pressure at the sigma level 0.995 is 995 hPa.
2) Are the sigma levels of the NCEP reanalysis model comparable to the a and b coefficients of the ECMWF model ?
The hybrid vertical coordinate of UCAR Community Atmosphere Model(CAM 3.0) describes a similar equation to that of ECMWF and has explicit coefficients A and B as shown below
$p(\eta,p_s) = A(\eta)p_0 + B(\eta)p_s$
where p is pressure, $p_s$ is surface pressure, $p_0$ is a specified constant reference pressure and A and B are coefficients that specify the coordinate being used and are defined only at the discrete model levels.
GOAL - I have code that uses ECMWF data as input to run a few calculations. I am looking to run the same code using NCEP renanalysis model data.
Page 6 Section 2.2.1 Vertical Discretization
Simmons, A.J., Burridge, D.M., An Energy and Angular Momentum Conserving Vertical Coordinate Finite Difference Scheme and Hybrid Vertical Coordinate, Monthly Weather Review 758-766,1981
Collins, W. D., P. J. Rasch, and Others, Description of the NCAR Community Atmosphere Model (CAM 3.0), Technical Report NCAR/TN-464+STR, National Center for Atmospheric Research, Boulder, Colorado, 210 pp., 2004. CAM