This dataset provides an annual average climatology of planetary boundary layer (PBL) height derived from COSMIC/FORMOSAT-3, TerraSAR-X, KOMPSAT-5, and PAZ Global Positioning System (GPS) radio occultation (RO) measurements. The COSMIC/FORMOSAT-3 mission consists of a six-satellite constellation launched in 2006. Each satellite carries an Integrated GPS Occultation Receiver (IGOR) GPS receiver and is equipped with fore and aft looking antenna to track both setting and rising occultations. The constellation provides globally distributed measurements across different local times. The instrument tracks the L-band microwave signal broadcast by a GPS satellite in a limb-viewing geometry. The IGOR receivers are capable of tracking the GPS signals in open loop through the middle to lower troposphere, which is essential for obtaining data with high quality for PBL height estimation, especially at low latitudes. The refractivity profiles form the basis for this PBL height product. For each occultation, the PBL height is calculated as the height where the vertical gradient of the refractivity (dN/dz) is minimum. This algorithm is designed to locate the height where a large vertical change in refractivity occurs, corresponding to the transition from the free troposphere to the PBL. More details can be found in Ao et al. (2012). This is the latest version of this collection which supercedes previous versions.