Where can I get the topography data used in the CARRA

Datasets and Usage C3S - Datasets and Usage
1

Hi,

Is it possible to get the elevation/topography data in 2.5km resolution used in the CARRA? I would like to get the difference between CARRA and in-situ observation over Greenland, in which effects by the lapse rate will be considered.

Best regards
Tinghai

2

Sorry if this is too late to be helpful, my account got suspended for a bit because I tried putting links in my response. Here it is with links removed, hopefully it’s easy to find the pages I refer to with a Google search.

CARRA derives its 2.5km orography primarily from ArcticDem v7 produced by the University of Minnesota Polar Geospatial Center (PGC). In particular, the CARRA full system documentation, appendix 6 says

Orography: Baseline dataset with GMTED2010 in ca 300m resolution + ArcticDem v7.0 over Greenland (2 m) with corrections on gaps using dataset of ArcticDem v6.0 , AsterDem and TanDem X + consistency correction about coast lines in Greenland with land-sea mask data from Danish Map Supply.

So, for your purpose, it may be more worthwhile to retrieve data from one of those DEMS to get higher resolution data, which is also more widely used (many climate models/papers use the ArcticDem, but few focus on CARRA’s more processed, niche elevation dataset).

However, if the resolution or data cleaning used by CARRA is helpful to you, it is also possible to retrieve the orography data used by CARRA as part of the “Arctic regional reanalysis on single levels from 1991 to present” product on the Copernicus Data Store. For Greenland, you’ll want to select the west domain of data, and you’ll need to select “surface or atmosphere” rather than “soil level” in order for orography to be a valid variable.

To request this data in Python with the CDS API, you can use the following code after setting up the cdsapi package with your API key and user information.

import cdsapi

dataset = "reanalysis-carra-single-levels"
request = {
    "domain": "west_domain",
    "level_type": "surface_or_atmosphere",
    "variable": ["orography"],
    "product_type": "analysis",
    "time": ["00:00"],
    "year": ["2025"],
    "month": ["01"],
    "day": ["01"],
    "data_format": "grib"
}

client = cdsapi.Client()
client.retrieve(dataset, request).download()