The Advanced Microwave Precipitation Radiometer (AMPR) was deployed during the Texas-Florida Underflights (TEFLUN-A); the first of three TRMM ground validation missions. AMPR data were collected at four microwave frequencies (10.7, 19.35, 37.1 and 85.5 GHz) for the period of 15 April 1998 through 04 May 1998. The TEFLUN-A mission studied convection over sub-tropical land and ocean regions within the range of research-quality radar, lightning, radiosonde, and raingage sites in Florida and Texas.