The BOREAS AFM-03 team used the NCAR Electra aircraft to make sounding measurements to study the planetary boundary layer using in situ and remote-sensing measurements. Measurements were made of wind speed and direction, air pressure and temperature, potential temperature, dewpoint, mixing ratio of H2O, CO2 concentration, and ozone concentration. Twenty-five research missions were flown over the NSA, SSA, and the transect during BOREAS IFCs 1, 2, and 3 during 1994. All missions had from 4 to 10 soundings through the top of the planetary boundary layer. This sounding data set contains all of the in situ vertical profiles through the boundary layer top that were made (with the exception of "porpoise" maneuvers). Data were recorded in 1-second time intervals.