Abstract We addressed the sensitivity of Global Navigation Satellite System (GNSS) radio occultation (RO) measurements to atmospheric horizontal variability based on realistically simulated data. Retrieved parameters from refractivity via pressure, and geopotential height to dry temperature were investigated. The errors in a realistic horizontally variable atmosphere relative to errors in a spherically symmetric atmosphere were quantified based on an ensemble of 60 occultation events. These events have been simulated using ray tracing through a representative European Centre for Medium-Range Weather Forecasts (ECMWF) T213L50 analysis field with and without horizontal variability, respectively. Below ∼7 km height biases and standard deviations of all parameters under spherical symmetry are significantly smaller than corresponding errors in a realistic atmosphere with horizontal variability. The relevance of the geometry of reference profiles was assessed in this context as well. A significant part of the total error below ∼7 km can be attributed to adopting reference profiles vertically at mean tangent point locations instead of extracting them along actual 3D tangent point trajectories. The sensitivity of retrieval products to the angle-of-incidence of occultation rays relative to the boresight direction of the receiving antenna was analyzed for three different azimuth sectors (0–10°, 20–30°, 40–50°) with 20 events in each sector. Below about 7 km, most errors were found to increase with increasing angle of incidence. Dry temperature biases between 7 and 20 km exhibit no relevant increase with increasing angle of incidence, which is favorable regarding the climate monitoring utility of the data.