During the International H20 Project 2002 (IHOP 2002), Reference Radiosondes were released sixteen times. Either a Vaisala RS80 radiosonde released from the Homestead site or a National Weather Service (NWS) VIZ radiosonde released from Dodge City, KS accompanied the Reference Radiosondes during their flights. Consult the README for dates and times when the Reference Sondes were released and from which site sondes were released simultaneously. There are some issues with the Reference Radiosonde data. The following is just a summary. For a more detailed explanation please see the "Important Notes to Users" section in the readme file. Pressure Errors: The Reference Sonde (RS) uses a hypsometer to measure pressure, and this sensor hasbeen found to be unreliable. We suggest not using the RS pressure data. Time difference: The time difference in the launch time between the RS sounding files and the VIZ/Vaisala soundings is due to the RS recording data on the ground, while the other sondes began recording closer to, or at, the actual launch time. Wind data: The RS wind data were not corrected for balloon pendulum swing because the effects of the balloon swing are large, they vary from sounding to sounding, and because the focus of the RS for IHOP was on the humidity measurements.