The SM retrievals from active MW sensors, which provide estimates of the water saturation of the 5 cm topsoil layer in relative units between 0 and 100 [%], are estimated using the WARP 5.2 change detection method. The dual channel VUA-NASA Land Parameter Retrieval Model is used to convert brightness temperatures from passive microwave sensors to soil moisture values . In order to generate a consistent product for a long term, an extra step is necessary to merge SM retrievals from different satellites over different periods to remove the system error. A backwards propagating cumulative distribution function matching approach is applied to scale passive SM data sets into a common radiometer and active SM estimates into a common scatterometer climatology using the most recent data sets as reference. AMSR-E is used for the passive data sets and ASCAT is used for the active ones.The earlier passive observations are successively matched to the passive reference to generate individual CCI-passive product over 30-year period. Ultimately, CCI-active and CCI-passive are then merged to a blended dataset based on the sensitivity to vegetation density. CCI-active is used over moderate vegetation areas while CCI-passive is adopted over low vegetation areas