Clarification on native resolution and interpolation for S2S Real-time dataset

Datasets and Usage Other - Datasets and Usage
1

Dear ECMWF Support Team,

I am currently retrieving ECMWF subseasonal model data from the S2S database (Realtime, Instantaneous and Accumulated) using the following MARS request:

retrieve,
class=s2,
dataset=s2s,
date=2026-03-01/to/2026-03-31,
expver=prod,
levtype=sfc,
model=glob,
number=1/50/100,
origin=ecmf,
param=121,
step=18/24/30,
stream=enfo,
time=00:00:00,
type=pf,
target="output"

While I successfully downloaded the data, I have some questions regarding the native spatial resolution of the archive and how regridding is handled:

  1. Is the native archived resolution of this specific dataset 1.5 degrees?

  2. If I specify a target grid resolution of 0.125 degrees in my retrieval, does the system simply perform spatial interpolation directly from the 1.5-degree archived data?

I am asking because our administration receives the commercial real-time S2S model forecasts at a 0.4-degree resolution. When I compare the fields retrieved from the S2S archive with our 0.4-degree real-time commercial feed, the results look significantly different.

Any insights into why these discrepancies occur or how the interpolation is processed on the backend would be greatly appreciated.

Best regards,

Chih-Chia Wang