I'm running a ROMS configuration for the northwestern European shelf region. The configuration has 1/4° by 1/4° resolution, and some smoothing of the bathymetry is applied to avoid horizontal pressure gradient errors. It's forced by ERA_interim atmospheric forcing and GLORYS lateral ocean boundary conditions. We're focusing on sea level output. I've received the input files from another researcher and encountered some problems setting this configuration up on the HPC environment of my institution. The model is running OK, but I'm getting dissimilar results in terms of time-mean sea level.
I have triple-checked that all my input settings agree with the files that I received. I'm using the latest version of ROMS at the time of downloading, i.e. version 3.7 SVN revision 966M. When running for 10 years, I get the following time-mean sea level (left panel), which is different from the 'original' results obtained by the colleague that tuned the model using version 3.7 revision 783 (middle panel). I included an observational product, albeit over a longer time period, for comparison (right panel):

In all cases the time-mean sea level displayed are anomalies with respect to the regional mean.
I proceeded downloading the revision 783 src code on my HPC environment, and ran the experiment again. The result was exactly the same as the middle panel. So, it seems like the solution of the original model is strongly affected by updates in the ROMS version. It seems odd that a different version can have so much effect. We would like to find out if there are particular reasons that could cause the differences that we're seeing? Any help would be greatly appreciated, and I'm happy to provide more information is needed.
Kind regards,
Tim