A note on atmospheric predictability

Authors: BENGTSSON, LENNART; HODGES, KEVIN I.

Source: Tellus A, Volume 58, Number 1, January 2006 , pp. 154-157(4)

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Abstract:

Using the method of <link rid="b4">Lorenz (1982), we have estimated the predictability of a recent version of the European Center for Medium-Range Weather Forecasting (ECMWF) model using two different estimates of the initial error corresponding to 6- and 24-hr forecast errors, respectively. For a 6-hr forecast error of the extratropical 500-hPa geopotential height field, a potential increase in forecast skill by more than 3 d is suggested, indicating a further increase in predictability by another 1.5 d compared to the use of a 24-hr forecast error. This is due to a smaller initial error and to an initial error reduction resulting in a smaller averaged growth rate for the whole 7-d forecast. A similar assessment for the tropics using the wind vector fields at 850 and 250 hPa suggests a huge potential improvement with a 7-d forecast providing the same skill as a 1-d forecast now. A contributing factor to the increase in the estimate of predictability is the apparent slow increase of error during the early part of the forecast.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1600-0870.2006.00156.x

Affiliations: 1: Environmental Systems Science Centre (ESSC), University of Reading, Harry Pitt Building, Whiteknights, Reading, RG6 6AL, United Kingdom

Publication date: 2006-01-01