Office for Outer Space Affairs
UN-SPIDER Knowledge Portal
Help Shape the Future of the UN-SPIDER Knowledge Portal
The UN-SPIDER Knowledge Portal is your one-stop platform for resources on space-based disaster risk management. It provides: • Links and guidance on satellite data sources and applications • Recommended practices and step-by-step methodologies • Training materials and tutorials • Case studies and user stories from real-world applications • News and updates on UN-SPIDER activities, events, and global developments
Since its last major review in 2012, the Portal has evolved significantly. Now, we want to hear from you.
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A major reassessment of 18 years of satellite observations has provided a new, more detailed view of sea-level change around the world. Incorporating the data from a number of spacecraft, the study re-affirms that ocean waters globally are rising by just over 3mm/yr. Measuring ocean surface shape from satellites has a relatively short history. Routine observations began with Europe's ERS-1 spacecraft in 1991, and this has subsequently been followed up by a series of international missions. The benchmark today is arguably Jason/Poseidon - a cooperative venture between the US and Europe (principally France). Now in its third incarnation, the Jason satellite circles the globe making a topographic map of 95% of the Earth's ice-free oceans every 10 days. To do this, it uses a radar altimeter, which constantly bounces microwave pulses off the sea surface.