I am using Sentinel-2A data for the area of south-eastern Australia. However, despite that the revisiting time of Sentinel-2A satellite is 5 days, I found that images for my study area have a rather low temporal resolution. Sometimes I need to wait for nearly 20 days before a new image is available. I found that for some places, like Europe and North America, the temporal availability is higher than my study area of south-eastern Australia. So I am wondering whether it is a normal phenomenon or not? Thank you~
The revisit time of the Sentinel-2 constellation (i.e with both satellites acquiring data) will be 5 days providing the same viewing conditions can be met (i.e there is no cloud cover etc.). Currently, only one satellite has been launched, and thus the revisit frequency of the satellite is greater than with two.
The reasoning for the acquisition of selected parts of the globe is a consequence of the mission being in the Ramp-Up Phase. As it states here: https://sentinel.esa.int/web/sentinel/missions/sentinel-2/operations-ramp-up-phase
A gradual ramp-up of the system performance is currently being defined, increasing gradually the observations capacity as well as the mission performance level in a stepwise approach.
This will include:
A gradual increase of acquisition capacity from an initial observation/processing scenario mainly focusing on Europe during the spacecraft in-orbit commissioning phase up to full systematic observation of the world at the end of the ramp-up phase
ensuring coverage of global Cal/Val needs during all times
ensuring as early as possible Copernicus Services dataset needs starting from Europe and extending gradually to the rest of the world
ensuring maximum coverage/optimised orbit length for generation of the Global Reference Image (GRI), required to produce high accuracy L1C products. This may take up to 9 months after IOCR to complete
ESA regularily release the forthcoming Acquistion Plans of the Sentinel-2 mission. They can be found here: https://sentinel.esa.int/web/sentinel/missions/sentinel-2/acquisition-plans. Used in conjunction with the Sentinel-2 L1C Tiling Grid (available under the Key Resources portlet on the same page) the Orbits over your AOI can be plotted.
Any unplanned events - outages of the instrument etc - are identified in the ESA RSS News feed. This can be found in the blue footer of each page of the Sentinel Online https://sentinel.esa.int/web/sentinel/ site.
I hope this is of help.
S2 MPC Operations Manager
Thank you very much for your very detailed answer. It is really helpful to me~