Issue with Mars service access

[gitRonang]

Hello,
I have download all ai-models and their assets, but when I wan't to do some inference, I got this API exception:
" ecmwfapi.api.APIException: "ecmwf.API error 1: User '[myadressmail]' has no access to services/mars"

However, on the ECMWF web site I see that public members have access to Mars services? Any advice to avoid that?

Thank you

[chengshenlian]

@gitRonang
While attempting to access and use the ECMWF's MARS dataset, I encountered similar issues. It became evident that my account lacked the necessary permissions to access the MARS dataset via the ECMWF web API. According to the information on ECMWF's official website (Accessing Forecasts), only authorized users from ECMWF member countries and World Meteorological Organization (WMO) members are granted such access permissions. Additionally, a commercial license is available for purchase at a cost of 3000 euros per year (related order link).

In light of these restrictions, I shifted my focus to using the CDS (Climate Data Store) free dataset for testing purposes. Although this dataset lags by 4-5 days compared to the latest data, it still suffices for regular testing needs.

Based on my experience, if a project is solely intended for research purposes, I would recommend using the CDS dataset. For those who are not internal authorized users and need access to nearly real-time MARS dataset, purchasing a commercial license, costing 3000 euros per year, is necessary.

In practice, I found that processing the CDS dataset with an A100 80GB graphics card for 4 minutes was sufficient to generate a graphcast.grib file for the next 10 days. This demonstrates that, despite some timeliness limitations, the CDS dataset remains a very effective and practical option.

[chomutovskij]

@chengshenlian could you please share the link where you found that MARS is nearly real-time?

All the documentation on ERA5 that I found so far (links included below) mention 5 day latency.

https://confluence.ecmwf.int/plugins/servlet/mobile?contentId=181127817#content/view/181127817

ERA5 is a comprehensive reanalysis, from 1940 to 5 days behind real time

https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-pressure-levels?tab=overview

ERA5 is updated daily with a latency of about 5 days.

https://climatedataguide.ucar.edu/climate-data/era5-atmospheric-reanalysis

Each day one new day is added that is 5 days behind real time.

[chengshenlian]

@chomutovskij
I recently reviewed the official documentation of ai-models regarding the use of MARS.
The original text states: “By default, ai-models use yesterday's 12Z analysis from ECMWF, fetched from the Centre's MARS archive using the ECMWF WebAPI. You will need an ECMWF account to access that service.”

Therefore, initially, I assumed that through MARS, it was possible to access the most recent day's data. Subsequently, after reviewing the commercial license, I discovered that real-time products could be accessed through ECMWF, leading me to speculate that the ECMWF Web API might provide real-time data access.

However, after considering the information you provided, I realize that regardless of whether it is through the MARS API or the CDS API, we can only access the ERA5 dataset. This dataset has an approximate delay of five days. Since I have not used the MARS API and do not have the necessary permissions, I am unable to provide more accurate information on this matter. Therefore, we need an explanation from official or authoritative channels to clarify which dataset can provide nearly real-time data, thereby enabling real-time 10-day weather forecasting.