An infrared Heterodyne Radiometer (IHR) located at Langley Research Center, Hampton, Va., has been used to study the seasonal variation of the vertical distribution of atmospheric ammonia. The ammonia profiles are inferred from high resolution atmospheric solar transmittance measurements around the ammonia absorption feature at 927.32323 cm-1. The transmittance data are obtained from six IF channel with spectral resolutions ranging from .0067 cm-1 to .033 cm-1. Results from this study show a marked decrease in the tropospheric ammonia level with a decrease at ground level from ~10 ppb in March 1979 to ~1.3 ppb in August 1979.