IMERG is now available back to June 2000 of the TRMM era. Both the 'early'
and the 'late' products have been retrospectively processed. These products are available in the same location on the jsimpson.pps.eosdis.nasa.gov FTP server as the current GPM IMERG products: /NRTPUB/imerg/early/YYYYMM and /NRTPUB/imerg/late/YYYYMM.
We are in the process of retrospectively processing the GIS-friendly versions and accumulations of these IMERG products. This is likely to be completed by the end of September 2019.
A very important item is that we have been directed to eliminate ftp to all our servers. We know that many of you have scripts that automatically retrieve data. PPS is attempting to impact you as little as possible. We are putting up an FTPS server. This means that as long as you have a client that support FTPS you should be able to use almost extactly the same commands as you currently use.
We will soon announce a public access to this FTPS server. You can then test new FTPS scripts against the FTPS server in parallel with continued retrieval using ftp (thereby not interrupting your operational flow). We hope to be able to provide this parallel access for six months. After 6 months we will be required to eliminate FTP totally.