The statistical minimum-rms inversion method used to obtain temperature profiles, requires estimates of covariance matrices and means for Planck function profiles of the atmosphere. In order to obtain these estimates over the pressure range of IWO to 0.01 mb, it was necessary to combine data from temperature measurements by radiosondes, rocketsondes and grenadesondes. Radiosonde data reaching the 10-mb level were extended to higher levels by means of a modified regression technique. Matrices and means have been obtained by this method for seasonal and geographical groupings in the Northern Hemisphere and the tropics. Details of the geographical and time changes in the matrices and the means are presented.