Earthdata Forum

Hi everyone,

I have a question regarding the availability of MODIS products, specifically MOD09A1 and MYD09A1 (8-day surface reflectance composite). Typically, I observe that these products become available within 2-3 days after the end of the acquisition period. However, occasionally, there are significant delays, with some products taking 5-10 days or even longer.

For example, the latest available image I can access is from November 8th, which corresponds to a composite ending on November 15th. The subsequent image, covering the period from November 16th to November 23rd, is still unavailable as of December 1st.

I’m curious to know:

What factors affect the delay in releasing these images?
What is the typical time frame for these products to be published after the end of their acquisition period?
Are there any common issues, such as processing backlogs or data quality checks, that might contribute to these delays?
I appreciate any insights or experiences you can share. Thank you!

Hello,
Sorry for the delay with the data processing. There are many factors that can affect data processing. It can be sensor and/or satellite related such as maneuvers and satellite issues. There will probably be more of this as Terra and Aqua age. Also, there can be issues at MODAPS as far as infrastructure goes, a couple years ago it was for a week to replace the electrical system. Also, sometimes they need to wait for input data for specific products. There are times it may be software or hardware issues. In this case, it could be they were short staffed because of the holiday week. I noticed the MOD09GAs were backed up a couple of days, but 3 days came in yesterday morning. Backlogs have certainly been an issue in the past, there was a time when they were processing the MODIS V006, V061 and all the VIIRS products at the same time. That should not be the case now though. I would expect the data very soon, seeing that the GAs are all caught up.

I think you are right when you say "typical" is 2-3days. A good way to figure average is to look at ingest days in the Data Pool: https://e4ftl01.cr.usgs.gov/MOLT/MOD09A1.061/
It has the dated files on the left and the date on the right shows when it was ingested.
Thanks for your patience and let me know if you have any questions.
Thanks,
Brett