PRISM FTP Server README file
Last updated 2025-03-27

FTP server hostname:  ftp://prism.oregonstate.edu

This FTP server exists to distribute PRISM data to the public.
The PRISM Datasets document (PRISM_datasets.pdf), available at the top level of the FTP server, contains detailed information about PRISM data.

IMPORTANT NOTES:

======= Notes - Section 1 =======

  ftp://prism.oregonstate.edu
   |- daily
   |- time_series_archive
   |- monthly
   |- normals_bil

This section of the FTP directory structure has been in place for many years:
 * Contains PRISM data with 'data stability' in filenames (e.g., PRISM_ppt_provisional_4kmD2_20250101_bil.zip)
 * Raster data distributed in BIL (Binary Interleaved by Line) format
 * Spatial resolution: 4km only


======= Notes - Section 2 =======

  ftp://prism.oregonstate.edu
   |- time_series
   |- normals

This section of the FTP directory structure (added Feb 2025) makes these changes:
 * Raster data are now distributed in COG (Cloud-Optimized GeoTIFF) format (see https://cogeo.org)
 * Filenames use the internal PRISM naming scheme (e.g., prism_ppt_us_30s_20250101.zip)
    - note that 15s ≡ 400m, 30s ≡ 800m, 25m ≡ 4km (s = seconds, m = minutes)
 * Regions (us, hi, ak, pr) added at second level of time_series & normals directory structures
    - PRISM data for Hawaii, Alaska, and Puerto Rico will be added as they are produced
    - "us" contains data for the 48 conterminous states
    - "hi", "ak", "pr" will contain regional data as they are completed
 * Spatial resolution (400m, 800m, 4km) added at third level 
    - added 800m, which is now available to the public in addition to 4km
    - added 400m, which will be used for Hawaii and Puerto Rico
 * PRISM variable (ppt, tmin, tmax, etc.) added at fourth level
 * Temporal resolution (daily, monthly) added at fifth level


======= Notes - Section 3 =======

On 30 September 2025, we will deprecate the directory structure described in Section 1 above. It will be replaced by the directory structure described in Section 2. Please update all scripts to fetch data from the directory structure in Section 2. We will eventually only update data in the Section 2 directory structure.