SMHI datasets (HARMONIE/V1, HARMONIE/V2)
Spin-up issues
Description:
The largest spin-up issues occurs during the first 2 hours of the forecast. It is therefore recommended to primarily use the 6 hourly analysis fields whenever this is possible. Also, it seems that three hourly values can be used without larger restriction. The spin-up problems are most pronounced during turbulent conditions, for example connected to deep low pressure systems, and should therefore be limited in space and time.
These spin-up problems are in some situations causing too high wind speeds for the 1-2 hour forecasts. This is most pronounced in the wind gust but the problem also occurs for the mean wind at 10 meter altitude. Similar problems can be seen for maximum/minimum temperature. Then in general there is a spin-up problem for precipitation. Here, it is not recommended to use the first 6 hours of the forecasts. Therefore, if a user wants to use the 24 hour accumulated precipitation it is recommended to use the 30-6 hour forecasts.
Wrong 0% values in relative humidity, cloud cover and albedo fields
Description:
There are some isolated spots of one or a few grid points with wrong zero values in the fields of relative humidity (both at 2m and on pressure levels). It happened because of a wrong algorithm used for re-computation of the values from 0-1 interval to 0-100% (the supersaturation was set to 100% instead of 0% value).
The same issue can be probably found in cloud cover and albedo fields as well but its extent there is not known.
Missing values in surface sensible heat flux and surface latent heat flux fields
Description:
The sensible heat flux and surface latent heat flux fields appear to have missing values over the land and because of that should not be used.
Land-sea mask to be used to downscale MESCAN-SURFEX fields
Description:
The UERRA-HARMONIE reanalyses need to be downscaled from 11km to 5.5km in order to drive the MESCAN-SURFEX system. For that a corresponding land-sea-mask field is needed, which is currently not archived in MARS. As a solution, please download that land-sea-mask field here. We recommend users to apply it for all the MESCAN-SURFEX fields and to focus their analysis on land points only.
More information and an illustration of potential issues when not using the appropriate LSM can be found in the related C3S support ticket.
MO datasets (UM, UM/En)
The wind directions are wrong by exactly 180 degrees
Description:
The wind directions are wrong by exactly 180 degrees (the direction is the wind is blowing to, rather than where it is blowing from) The U/V components are not affected.
Météo-France datasets (MESCAN-SURFEX)
Soil level parameters are inverted with respect to their Y-axis
Description:
Both of the fields provided by Météo-France for the UERRA soil levels (Volumetric transpiration stress-onset (soil moisture) and Volumetric wilting point) are inverted with respect to their Y-axis