Tellus: Series A, Dynamic Meteorology and Oceanography (Mar 2012)

Control of lateral boundary conditions in four-dimensional variational data assimilation for a limited area model

  • Nils Gustafsson

DOI
https://doi.org/10.3402/tellusa.v64i0.17518
Journal volume & issue
Vol. 64, no. 0
pp. 1 – 14

Abstract

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The limited area model forecasting problem is a lateral boundary condition (LBC) problem in addition to the initial condition problem. The data assimilation has traditionally been considered as a process for estimation of the initial condition only, while for the limited area data assimilation this estimation may be extended to include also the LBCs, at least during the data assimilation time window when observations are available. A procedure for such a control of the LBCs has been included in the four-dimensional variational data assimilation (4D-Var) scheme for the HIgh Resolution Limited Area Model (HIRLAM) forecasting system. A description of this procedure is provided together with results from idealised as well as real data experiments. The results indicate that control of LBCs may be important with small forecast domains and in particular for weather disturbances moving quickly into and through the forecast domain.

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