Radio occultation observations gridded to daily 2.5°x2.5° fields by a Gaussian weighted average over ±2 days and 15°x5° longitude-latitude, based on radio occultation profile data version OPSv5.6.2. A detailed description of this data is given in Brunner and Steiner (2017): https://doi.org/10.5194/amt-10-4727-2017