The TCSP Aerosonde dataset consists of measurements of air temperature, pressure, and relative humidity were made on each flight using two Vaisalla RS902 sondes located under the wings of the aerosonde aircraft. A Heiltronics KT11.k6 infrared pyrometer was used to measure sea surface temperatures (SST). The TCSP Field Experiment was held during the month of July, 2005, in Costa Rica. The mission was to study the processes associated with tropical waves passing over Central America to the Pacific ocean, where they would eventually form tropical cyclones.