# \#mars **URL:** https://forum.ecmwf.int/tag/mars/63.md [Latest](https://forum.ecmwf.int/latest.md) · [Categories](https://forum.ecmwf.int/categories.md) · [Tags](https://forum.ecmwf.int/tags.md) --- ## [combining Mars dataset after downloading it on a monthly or yearly time step](https://forum.ecmwf.int/t/combining-mars-dataset-after-downloading-it-on-a-monthly-or-yearly-time-step/14733)
**Author:** [@James\_Oti](https://forum.ecmwf.int/u/James_Oti)\ **Replies:** 0\ **Last updated:** [18 February 2026 17:05 UTC](https://forum.ecmwf.int/t/combining-mars-dataset-after-downloading-it-on-a-monthly-or-yearly-time-step/14733 "2026-02-18T17:05:25Z")
Hello I have downloaded yearly and monthly data from the Mars server. I get this error “ValueError: Resulting object does not have monotonic global indexes along dimension valid\_time” after trying to open with mfdatas… --- ## [Minor difference between MARS archive data and ](https://forum.ecmwf.int/t/minor-difference-between-mars-archive-data-and/14253)
**Author:** [@Toshiyuki\_Bandai](https://forum.ecmwf.int/u/Toshiyuki_Bandai)\ **Replies:** 0\ **Last updated:** [14 October 2025 09:26 UTC](https://forum.ecmwf.int/t/minor-difference-between-mars-archive-data-and/14253 "2025-10-14T09:26:10Z")
I’m seeing small differences between ECMWF Open Data and MARS. For example, when I compare the temperature data at p = 1000 hPa for step=24h at 0.25 degrees resolution between ECMWF Open Data and MARS, there is a tiny di… --- ## [API Request failing with internal MARS-server error](https://forum.ecmwf.int/t/api-request-failing-with-internal-mars-server-error/883)
**Author:** [@Christopher\_Subich](https://forum.ecmwf.int/u/Christopher_Subich)\ **Replies:** 1\ **Last updated:** [10 January 2024 14:55 UTC](https://forum.ecmwf.int/t/api-request-failing-with-internal-mars-server-error/883 "2024-01-10T14:55:14Z")
I've been downloading (among other things) surface-level information for relatively recent dates, and my download for February 2022 has failed. The most recent of these requests has the request ID f840acf6-8ed3-4ca0-… --- ## [Can I use forecast data in ERA5 MARS(stream=oper, type=fc) as NWP forecast?](https://forum.ecmwf.int/t/can-i-use-forecast-data-in-era5-mars-stream-oper-type-fc-as-nwp-forecast/1583)
**Author:** [@Mingtao\_Cui](https://forum.ecmwf.int/u/Mingtao_Cui)\ **Replies:** 0\ **Last updated:** [20 September 2023 03:02 UTC](https://forum.ecmwf.int/t/can-i-use-forecast-data-in-era5-mars-stream-oper-type-fc-as-nwp-forecast/1583 "2023-09-20T03:02:42Z")
I am working on a atmosphere-to-power AI model on a solar power station, and I am not sure whether I can use ERA5 MARs forecast data (stream=oper, type=fc) as NWP input data in my model. From ERA5 documentation, I see t… --- ## [Issue affecting access to ECMWF MARS archived products via CDS API](https://forum.ecmwf.int/t/issue-affecting-access-to-ecmwf-mars-archived-products-via-cds-api/1266)
**Author:** [@Anabelle](https://forum.ecmwf.int/u/Anabelle)\ **Replies:** 0\ **Last updated:** [4 June 2021 13:56 UTC](https://forum.ecmwf.int/t/issue-affecting-access-to-ecmwf-mars-archived-products-via-cds-api/1266 "2021-06-04T13:56:36Z")
There are technical difficulties with the ECMWF MARS Tape archive system where some CDS products are stored. These are currently being investigated. As a consequence of this, data requests for these datasets will remain … --- ## [Correct MARS request for ERA5.1](https://forum.ecmwf.int/t/correct-mars-request-for-era5-1/902)
**Author:** [@Tom\_Akkermans](https://forum.ecmwf.int/u/Tom_Akkermans)\ **Replies:** 2\ **Last updated:** [19 May 2020 07:53 UTC](https://forum.ecmwf.int/t/correct-mars-request-for-era5-1/902 "2020-05-19T07:53:26Z")
Hi, Given the recent ERA update to ERA5.1, i wanted to know if my new MARS request is correct. Below the parameters I supplied, the only change compared to my earlier script is parameter DATASET which i changed to era5… --- ## [ECMWF MARS system session](https://forum.ecmwf.int/t/ecmwf-mars-system-session/1002)
**Author:** [@Michela](https://forum.ecmwf.int/u/Michela)\ **Replies:** 0\ **Last updated:** [25 September 2019 14:10 UTC](https://forum.ecmwf.int/t/ecmwf-mars-system-session/1002 "2019-09-25T14:10:46Z")
We want to inform users that there is currently a ECMWF system session affecting access to MARS from CDS. In order to prevent failures, currently NO requests are being dispatched to MARS External. This might cause delays… --- ## [CDS Service - restricted access to ECMWF MARS on 19/8/19 and 21/9/19](https://forum.ecmwf.int/t/cds-service-restricted-access-to-ecmwf-mars-on-19-8-19-and-21-9-19/879)
**Author:** [@Kevin\_Marsh](https://forum.ecmwf.int/u/Kevin_Marsh)\ **Replies:** 0\ **Last updated:** [19 August 2019 10:39 UTC](https://forum.ecmwf.int/t/cds-service-restricted-access-to-ecmwf-mars-on-19-8-19-and-21-9-19/879 "2019-08-19T10:39:14Z")
The CDS group have just issued the following information: Please notice the following sessions affecting CDS: Monday 19th - Access to ECMWF MARS will be restricted between 12:30 - 14:30 BST because of ECMWF Network ses…