Landsat 8 currently acquires up to 725 images per day — up from the 550 images per day acquired in 2013.
Priorities assigned to each scene and special request help distribute the acquisitions.
Day-lit images are defined as images with sun elevations greater than five degrees. If fewer than 725 images per day exist, all candidates can be scheduled. If more than 725 candidate scenes exist, then images are excluded as a function of cloud cover prediction and long term cloud cover statistics. If the cloud cover prediction is better than the long-term average then the priority is increased. If an acquisition is rejected, a missed opportunity boost will take effect to increase the probability of future acquisitions.
The map below shows the priorities of Landsat 8 scenes as of 6 May 2015. The lower priority scenes are more likely to be rejected to meet the daily limit, while the highest priority scenes are only rejected for maneuvers or rare calibration events.
Figure 1. Distribution map of Landsat 8 Acquisition priorities
The graph below represents the distribution of candidate scenes through the year, if no special requests are scheduled. The orange region represents scenes that do not meet the day-lit criteria. The line is the 725 daily limit. The green region represents the scenes that are scheduled. The red region represents the scenes that are rejected due to the daily limit. The region between the green region and the gray line is the margin available for scheduling special requests that do not cause LTAP scenes to be rejected.
Figure 2. Annual distribution graph of Landsat 8 candidate scenes