Radio Occultation with CHAMP.- GPS Radio Occultation with CHAMP and GRACE: Recent Results.- Sensitivity of Stratospheric Retrievals from Radio Occultations on Upper Boundary Conditions.- Error Characteristics of Refractivity Profiles Retrieved from CHAMP Radio Occultation Data.- Refractivity Biases in GNSS Occultation Data.- Stellar Occultation with GOMOS.- GOMOS Ozone Profiles at High Latitudes: Comparison with Marambio and Sodankyla Sonde Measurements.- Ozone and Temperature Retrieval Results from GOMOS Validated with CHAMP and ECMWF.- Modeling Errors of GOMOS Measurements: A Sensitivity Study.- Wave Optics Algorithms for the Processing of Radio Occultation Data.- Asymptotic Wave Optics Methods in Inversion and Direct Modeling of Radio Occultations: Recent Achievements.- Processing Radio Occultation Data by Full Spectrum Inversion Techniques: An Overview and Recent Developments.- Evaluation of the Processing of Radio Occultation Signals by Reconstruction of the Real Signals.- Radio Holographic Filtering of Noisy Radio Occultations.- Future GNSS Occultation Missions and the LEO-LEO Occultation Concept.- Preparing for COSMIC: Inversion and Analysis of Ionospheric Data Products.- The Operational EPS GRAS Measurement System.- ROSA: The Italian Space Agency GPS Radio Occultation Receiver. Signal Tracking Characteristics and Terrestrial Measurement Campaign.- Tropospheric Water Vapor from LEO-LEO Occultation: Estimation by Differential Attenuation Measurements near 20 GHz.- Processing X/K Band Radio Occultation Data in Presence of Turbulence: An Overview.- Use of GNSS Occultation Data in Numerical Weather Prediction and in Atmospheric Studies.- Assimilation of GNSS Radio Occultation Data into Numerical Weather Prediction.- Observation Operators for the Assimilation of Occultation Data Into Atmospheric Models: A Review.- Analysis of Atmospheric and Ionospheric Wave Structures Using the CHAMP and GPS/MET Radio Occultation Database.- Are we Observing Mountain Waves Above the Andes Range from GPS Occultation Profiles?.- Analysis of Seasonal and Daily Mid-Latitude Tropopause Pressure Using GPS Radio Occultation Data and NCEP-NCAR Reanalyses.- CHAMP Radio Occultation Detection of the Planetary Boundary Layer Top.- Use of GNSS Occultation Data for Climate Monitoring and Climate Change Studies.- Monitoring Climate Variability and Change by Means of GNSS Data.- Climate Benchmarking Using GNSS Occultation.- Global Climatologies Based on Radio Occultation Data: The CHAMPCLIM Project.- Pre-Operational Retrieval of Radio Occultation Based Climatologies.- Assimilation of GNSS Radio Occultation Profiles into GCM Fields for Global Climate Analysis.