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Assimilation of low-level wind in a high-resolution mesoscale model using the back and forth nudging algorithm

Tellus: Series A, Dynamic Meteorology and Oceanography. 2012;64(0):1-15 DOI 10.3402/tellusa.v64i0.18697


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Journal Title: Tellus: Series A, Dynamic Meteorology and Oceanography

ISSN: 1600-0870 (Online)

Publisher: Taylor & Francis Group

Society/Institution: International Meteorological Institute

LCC Subject Category: Geography. Anthropology. Recreation: Oceanography | Science: Physics: Meteorology. Climatology

Country of publisher: United Kingdom

Language of fulltext: English

Full-text formats available: PDF, HTML



Jean-François Mahfouf

Alexandre Boilley


Blind peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 20 weeks


Abstract | Full Text

The performance of a new data assimilation algorithm called back and forth nudging (BFN) is evaluated using a high-resolution numerical mesoscale model and simulated wind observations in the boundary layer. This new algorithm, of interest for the assimilation of high-frequency observations provided by ground-based active remote-sensing instruments, is straightforward to implement in a realistic atmospheric model. The convergence towards a steady-state profile can be achieved after five iterations of the BFN algorithm, and the algorithm provides an improved solution with respect to direct nudging. It is shown that the contribution of the nudging term does not dominate over other model physical and dynamical tendencies. Moreover, by running backward integrations with an adiabatic version of the model, the nudging coefficients do not need to be increased in order to stabilise the numerical equations. The ability of BFN to produce model changes upstream from the observations, in a similar way to 4-D-Var assimilation systems, is demonstrated. The capacity of the model to adjust to rapid changes in wind direction with the BFN is a first encouraging step, for example, to improve the detection and prediction of low-level wind shear phenomena through high-resolution mesoscale modelling over airports.