How is the tropopause level calculated in the reanalysis?
[6/19/96] The model level analyses are used to calculate tropopause data. (A post processor is used). The procedure at NCEP looks for the lowest level above 450 mb where the lapse rate is under 2K per km. A more exact location for the tropopause between two model levels is determined, and the pressure and temperature are calculated for that spot in the vertical. The trop is not allowed to be above 85 mb. In spite of changing observations, the analyses should be quite stable over time. Therefore the derived tropopause data should be stable over time. [From Kanamitsu. NCEP has a listing of the program used.] • The NCEP/NCAR Reanalyses provides diabatic heating components, with unit K/s. Is this heating the tendency of the POTENTIAL temperature, or just of temperature itself? [Jan, 1999] The diabatic heating (K/s) is the temperature tendancy and not the potential temperature tendancy. • How is the PV (potential vorticity) on the theta surface computed? [Jan 1999] The PV is first interpola
