Earthdata Forum

I am a subscriber of MODIS-Aqua L1 data for Indian ocean region (25 to 110E, -40 to 30N).

I fetch list of files for my ROI using
wget --load-cookies ~/.urs_cookies --save-cookies ~/.urs_cookies --keep-session-cookies \
--post-data="subID=$SubID&results_as_file=1" -q -O - https://oceandata.sci.gsfc.nasa.gov/api/file_search > ListAll.txt
more ListAll.txt | grep A$Year$day >ListRemote$Year$day.txt [ For shorting data for that particular day ]

And I do that daily.

I want to know by what time (UTC) all the L1 files for this region become available in the web.

Let say, for 19th Feb 2020, Sunset at Port Elizabeth (~25E) is at 19:00 Local time i.e. 17:00 UTC and it is night time in Indian Ocean. So data acquisition for all ocean color day products is over for the date for this region. There will be transfer of raw data from satellite to ground stations, different processing and finally dissemination, so there will be a time delay between raw data acquisition of last LAC (of the above mentioned ROI) and that data comes online. My question is at what time all the L1 data from this region become available in the web?

That's a question that cannot be answered with any confidence.   Nominally, the data are available within about 4-8 hours after collection, but there are too many factors involved (several of which you identified) to be able to  provide a reliable estimate.  It is now ~1330 UTC and data collected over the Indian Ocean for today (at ~0830 UTC) are available on the L1/L2 browser (which has additional latency over the L1 subscription). 

Sean