The results of three tropospheric ion field studies are presented along with new identities and a discussion of ion variability. The ion identifications were made using a dual collision chamber tandem mass spectrometer. Included among the species recently identified are isobutylamine, 2-dimenthylaminoethanol and/or sarcosine, SO4NO-2, SO4NO-3, and a species that appears to be similar to glucose containing an amine and 0-3 methyl groups and possibly some fairly massive (masses>200 amu) primary amines. The variability of most of the major ions in the positive spectrum is observed to be surprisingly small. For several of the more massive positive ions, this lack of variability is difficult to explain, since the atmospheric lifetime of the parent species of these ions should be short. ¿ American Geophysical Union 1990