Open AccessSequential assimilation of stratospheric chemical observations in a three‐dimensional model
Author(s) -
Chipperfield M. P.,
Khattatov B. V.,
Lary D. J.
Publication year - 2002
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2002jd002110
Subject(s) - stratosphere , assimilation (phonology) , data assimilation , atmospheric sciences , occultation , chemical transport model , environmental science , ozone depletion , physics , meteorology , astrophysics , troposphere , linguistics , philosophy
We describe a technique to assimilate chemical observations in a three‐dimensional (3‐D) chemical transport model (CTM). The method uses the established sequential technique of Khattatov et al. [2000], but here, it is applied simultaneously to many observed species. Following the assimilation, care is taken to preserve compact correlations between all modeled long‐lived tracers and the total abundance of reactive families (e.g., inorganic chlorine). This way, the observations of long‐lived tracers and family members constrain many other species in the model. In this paper, we apply the technique to the assimilation of O 3 , CH 4 , H 2 O, and HCl from the Halogen Occultation Experiment (HALOE) in 1992. Despite the poor coverage of HALOE, the assimilation of species with long photochemical lifetimes is a useful global constraint on the model. Results of the assimilation model have been tested by comparison with Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) profiles of O 3 , CH 4 , H 2 O, HCl, and N 2 O. Direct comparison of the assimilated species shows that the assimilation model performs better in reproducing the independent observations. Comparison of the nonassimilated species (N 2 O) shows that assimilation has generally improved the comparison, especially in the midlatitude lower stratosphere.