Coherent change detection for urban development monitoring

Coherence measurements provide a tool with significant potential for detecting change. To reduce the likelihood of missed events data from both ascending and descending orbits should be used. Data from ascending orbits (which is acquired at 22.00 hrs GMT) lead to higher coherence values than that from the descending orbits (at 11.00 hrs GMT); possibly as a result of ionospheric effects: however the data available were over a restricted period. The resolution of ERS data imposes a fundamental limit to the sensitivity of the change measurements through the size of the coherence measurement window