| Home > Research > Ifsdocs > ASSIMILATION > |
DATA ASSIMILATION
IFS documentation Front Page
Table of contents
CHAPTER 1 Incremental
formulation of 3D/4D variational assimilation-an overview
CHAPTER 2 3D variational assimilation
CHAPTER 3 4D variational assimilation
CHAPTER 4 Background term
CHAPTER 5 Conventional observational
constraints
CHAPTER 6 Satellite observational
constraints
CHAPTER 7 Background, analysis
and forecast errors
CHAPTER 8 Gravity-wave control
CHAPTER 9 Data partitioning (OBSORT)
CHAPTER 10 Observation screening
CHAPTER 11 Analysis of snow
CHAPTER 12 Land surface analysis
CHAPTER 13 SST and sea-ice analysis
CHAPTER 14 Reduced-rank Kalman filter
Previous Section
10.1 Introduction
This chapter describes the observation screening in the ECMWF 3D/4D-Var data assimilation. A more general description can be found in Järvinen and Undén (1997). The purpose of the observation screening is to select a clean array of observations to be used in the data assimilation. This selection involves quality checks, removal of duplicated observations, thinning of their resolution etc.. The new selection algorithm was implemented operationally in September 1996 and was designed to reproduce (to a large extent) the selection of observations that the old screening of the ECMWF OI analysis code used to make (Lönnberg and Shaw, 1985 and 1987; Lönnberg, 1989).
This chapter was prepared in September 1997 by Heikki Järvinen, Roger Saunders and Didier Lemeur, and updated in February 1999 by Roger Saunders for TOVS processing, by Elias Holm and Francois Bouttier for the remainder.
Next Section
Previous Section
 |
21.03.2002 |
 |
© ECMWF |
