18 December 2008. More than 85% of the ground pixels of GOME(-2) and SCIAMACHY are influenced by clouds. Therefore, detection of clouds is essential in obtaining precise tropospheric pollution information from these satellite sensors. Wang et al. [2008] have improved the FRESCO cloud detection algorithm by including Rayleigh scattering. Validation of the improved algorithm, FRESCO+, with groundbased radar observations shows that the FRESCO+ cloud pressure is the mid-level of clouds. It appears that FRESCO+ gives more reliable cloud pressures over partly cloudy pixels than FRESCO. Globally averaged, the FRESCO+ cloud pressure is about 50 hPa higher than FRESCO. Application of FRESCO+ to cloud correction of tropospheric NO₂ measurements from SCIAMACHY shows that the algorithm works better than the previous version. FRESCO+ is now the operational cloud algorithm for the TEMIS data products from GOME and SCIAMACHY (see: http://www.temis.nl).