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Please note that geopotential is not archived operationally on model levels in MARS at ECMWF. To compute geopotential on model levels use Metview's mvl_geopotential_on_ml() function. The following example shows how to use function mvml_to_hl() together with mvl_geopotential_on_ml() :
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# retrieve the data on model levels - surface geopotential (zs) is only available in the first forecast step! common_retrieve_params = ( type : "fc", levtype : "ml", step : 12, grid : [1.5,1.5] ) t = retrieve param : "t", levelist : [1, 'to', 137], common_retrieve_params) q = retrieve param : "q", levelist : [1, 'to', 137], common_retrieve_params) lnsp = retrieve( param : "lnsp", levelist : 1, common_retrieve_params) zs = retrieve( param : "z", levelist : 1, type : "fc", levtype : "ml", step : 0, grid : [1.5,1.5]) # compute geopotential on model levels z = mvl_geopotential_on_ml(t, q, lnsp, zs) # interpolate the t field onto a list of height levels above sea level hlevs = [1000, 2000, 3000, 4000, 5000] th = mvml_to_hl (t, z, nil, hlevs, "sea", "linear") |
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