ALOS Systematic Observation Strategy

The PRISM and AVNIR-2 Observation Plans

PRISM and AVNIR-2 are programmed for repetitive, global-scale observations, and like PALSAR, the observation strategy implemented aims to maintain both spatial and temporal consistency over regional scales. The timing of the regional observations has been determined based on cloud statistics, seasonality and sun elevation, although cloud cover inevitably limit the amount of useful data acquired.

The default mode for PRISM operations is the 3-telescope triplet mode to enable along-track stereo viewing. As the swath width in triplet mode is 35 km, two 46-day cycles are required to achieve a full regional coverage, during which the instrument is tilted alternately (+/- 1.2° ) in across-track direction.
The PRISM plan can be summarized as follows:

  • Odd cycle numbers: +1.2° viewing angle
  • Even cycles: -1.2° viewing angle

Some area will be operated by 2-telescopes observing mode (nadir 70km + backward 35km) based on the users requirement.

The default mode for AVNIR-2 is nadir view.

For any given region, AVNIR-2 is typically scheduled for "one acquisition during two consecutive cycles", meaning that if an acquisition is successfully programmed the first of the two cycles in question, it will not be included in the plan during the second (regardless of cloud cover).

For detailed views of which regions that are scheduled for acquisitions by the optical instruments during a particular cycle, click here for PRISM, and AVNIR-2, respectively.