The proposed CALT project aims to bring together the operators of existing and future satellite altimetry permanent calibration sites. This would improve the overall services for the altimeter biases and drifts for each satellite mission (e.g., Jason, Envisat, GFO, Altika, HY-2, Cryosat-2, Sentinel, etc.) and cross calibrate different missions at different world locations on a common and long-term ...