# SST increases unreasonably when run nemo with ERA5 data **URL:** \ **Category:** v4.2.x\ **Created:** [24 October 2024 13:12 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773 "2024-10-24T13:12:33Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![ttlin](https://avatars.discourse-cdn.com/v4/letter/t/7993a0/32.png) [@ttlin](https://nemo-ocean.discourse.group/u/ttlin)\ **Post date:** [24 October 2024 13:12 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/1 "2024-10-24T13:12:33Z")
Hello, I am doing the global simulation and running the NEMO with ERA5 data. I found the simulation results looks unreasonably in my experiment. Everything went well when I did the spin up with ncar. This is the setting what I use to do spinup ![image](https://global.discourse-cdn.com/free1/uploads/nemo_ocean/original/1X/0f1c33986990209bd853aaeeec473a157650c3c9.png) The tos from spinup is attached here ![image](https://global.discourse-cdn.com/free1/uploads/nemo_ocean/original/1X/be6df92e279b52472bfa69a49a63f8d3a2579168.png) After 40 years spinup, I change the atmosphere data to ERA5 data. This is the setting. ![image](https://global.discourse-cdn.com/free1/uploads/nemo_ocean/original/1X/05b6acea5225ced1f49c8c36924f847af12572a3.png) the value is unreasonable after I change the data ![image](https://global.discourse-cdn.com/free1/uploads/nemo_ocean/original/1X/3f2de60086375a508aa437e93d0afac18b7f9ab5.png) The Anartic Ocean looks crazy warm in my output. Has anyone met this issue before? Has anyone had experience running nemo with ERA5 data? I would appreciate anyone could help me out or give me some advice. Thanks in advance! ---
**Author:** ![robinson](https://avatars.discourse-cdn.com/v4/letter/r/848f3c/32.png) [@robinson](https://nemo-ocean.discourse.group/u/robinson)\ **Post date:** [24 October 2024 13:43 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/2 "2024-10-24T13:43:39Z")
Hei, The name of your ERA5 files suggests it is hourly data, but then the frequency in hours is set to 3 ? /robinson ---
**Author:** ![ttlin](https://avatars.discourse-cdn.com/v4/letter/t/7993a0/32.png) [@ttlin](https://nemo-ocean.discourse.group/u/ttlin)\ **Post date:** [24 October 2024 14:09 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/3 "2024-10-24T14:09:55Z")
Hi robinson, thanks for your reply！Actually, the ERA5 data is 3 hourly. Sorry for the confusing name. ---
**Author:** ![robinson](https://avatars.discourse-cdn.com/v4/letter/r/848f3c/32.png) [@robinson](https://nemo-ocean.discourse.group/u/robinson)\ **Post date:** [24 October 2024 15:24 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/4 "2024-10-24T15:24:13Z")
ok, so I’m comparing to my namelist (i also use ERA5), you have set time interp to false, and climatology to true, which are both strange choices since it is a re-analysis. Then there are all these choices of skin parametrization that i do not have in my nemo version, and also i cannot use dew point temp instead of specific humidity in my namelist. Is this temperature in the right unit for example ? ---
**Author:** ![ttlin](https://avatars.discourse-cdn.com/v4/letter/t/7993a0/32.png) [@ttlin](https://nemo-ocean.discourse.group/u/ttlin)\ **Post date:** [25 October 2024 08:16 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/5 "2024-10-25T08:16:38Z")
Hi robinson, can you share me your namelist? ---
**Author:** ![acc](https://avatars.discourse-cdn.com/v4/letter/a/b38774/32.png) [@acc](https://nemo-ocean.discourse.group/u/acc)\ **Post date:** [31 October 2024 13:47 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/6 "2024-10-31T13:47:57Z")
Have you checked that your weights files are giving you the correct interpolation on the fly? ERA5 has a known warm bias in the Arctic; wonder if your fields are upside down? ---
**Author:** ![ttlin](https://avatars.discourse-cdn.com/v4/letter/t/7993a0/32.png) [@ttlin](https://nemo-ocean.discourse.group/u/ttlin)\ **Post date:** [31 October 2024 13:56 UTC](https://nemo-ocean.discourse.group/t/sst-increases-unreasonably-when-run-nemo-with-era5-data/773/7 "2024-10-31T13:56:50Z")
Hi, the problem is solved. The reason is that Nemo keeps reading the first time step of the atmosphere forcing data during the simulation. I checked the input data and found that my data has a fixed time dimension. The problem was solved after I changed the time dimension to unlimited although I do not really know why it happens like that. Anyway, Thanks for your reply！