Capturing tropical instability waves in the ECMWF Coupled Reanalysis System

TitleCapturing tropical instability waves in the ECMWF Coupled Reanalysis System
Publication TypeReport
Date Published02/2015
Series/CollectionERA Report Series
Document Number17
Authorsde Boisséson, E, Laloyaux, P, Alonso-Balmaseda, M
Event Series/CollectionERA Report
Place of publicationShinfield Park, Reading

The European Centre for Medium-Range Weather Forecasts (ECMWF) has developed a prototype of ocean-atmosphere coupled assimilation system that will be used for 20th century reanalysis experiments. This system has been run over a two-year period using a century-reanalysis configuration. The ability of the system to capture intraseasonal coupled processes such as Pacific Tropical Instability Waves (TIWs) is evaluated against observations and an atmosphere-only reanalysis. The coupled reanalysis shows to be an improvement over the atmospheric reanalysis as it is able to capture these tropical instabilities with similar characteristics as the observed state except for relatively weak amplitudes. Experiments show that alternative methods to constrain the air-sea interface of the system may improve the representation of the tropical instabilities in the analysis fields.

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