CMIP model output is made available via the Earth System Grid Federation (ESGF) along with data from other projects including some obs4MIPs.
Obs4MIPs data published on ESGF is available as a companion project of CMIP via Metagrid. Currently, efforts are underway to introduce new datasets to obs4MIPs as well as to update existing products. ESGF is a primary platform for making many obs4MIPs compliant data available.