Pure and Applied Geophysics

, Volume 169, Issue 3, pp 367–379 | Cite as

Multivariate Data Assimilation in the Tropics by Using Equatorial Waves

  • Nedjeljka ŽagarEmail author


This paper reports recent advances in understanding of dynamical aspects of the tropical data assimilation. In contrast with the mid-latitudes, there is no a well-defined approach for the tropical data assimilation in numerical weather prediction (NWP) community which has traditionally been concentrated on the mid-latitude analysis problem. In particular, the impact of the equatorial Rossby, inertio-gravity, and mixed Rossby-gravity waves on the tropical forecast-error covariances is difficult to quantify. Various tropical waves are characterized by different couplings between the mass field and the wind field. The average mixture of these waves, built into the background-error covariance matrix for data assimilation provides analysis increments which appear nearly univariate even though they result from the advanced multivariate assimilation methodology. This applies to both dry and moist idealized tropical systems as well as to a 4D-Var NWP assimilation system.


Tropics Data assimilation 4D-Var Multivariate relationships Equatorial waves Moist processes 



The author would like to thank David Tan of ECMWF for allowing her to use his assimilation experiment with a single temperature observation in the ECMWF 4D-Var system. The Centre of Excellence for Space Sciences and Technologies SPACE-SI is an operation part financed by the European Union, European Regional Development Fund and Republic of Slovenia, Ministry of Higher Education, Science and Technology.


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Copyright information

© Springer Basel AG 2011

Authors and Affiliations

  1. 1.Faculty of Mathematics and PhysicsUniversity of LjubljanaLjubljanaSlovenia
  2. 2.Center of Excellence SPACE-SILjubljanaSlovenia

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