The GPM Ground Validation Advanced Microwave Precipitaiton Radiometer (AMPR) MC3E dataset was collected by the Advanced Microwave Precipitation Radiometer (AMPR) instrument, which played a key role in the Midlatitude Continental Convective Clouds Experiment (MC3E). The AMPR remotely sensed passive microwave signatures of geophysical parameters from an airborne platform. The instrument is a low noise system which provided multi-frequency microwave imagery with high spatial and temporal resolution. AMPR data were collected at a combination of four microwave frequencies (10.7, 19.35, 37.1, and 85.5 GHz) with two orientations each (Vpol-to-Hpol and Hpol-to-Vpol), which were complimentary to current aircraft and satellite instrumentation. These frequencies are best suited to the study of rain systems, but were also useful to studies of other atmospheric, oceanic, and land surface processes.