ROSE 3D Chemistry-Transport Model
DLR Version - Model Description
| Model resolution | |
| Horizontal: | Euler grid with 5° x 5.6° resolution (latitude/longitude) |
| Vertical: | 37 levels between 316 and 0.316 hPa (8-55 km) giving 1.3 km spacing |
| Temporal: | 15 min. for chemistry; 1.5 hours for transport |
| Output resolution: | 1h for validation purposes; 00, 06, 12, 18 UTC in operational use. |
Transport scheme
Semi-Lagrange transport driven by daily UKMO wind fields (Smolarkiewicz, 1995).
Chemistry
Gas-phase chemistry is based on the family-concept as formulated by Rose and Brasseur, 1989 (revised 1996). Reaction rates are calculated using daily temperature fields from UKMO and pre-calculated photolysis frequencies depending on local insolation and ozone column. Differential equations are solved by a semi-implicit scheme.
| Transported species | Equilibrium species |
|
Ox HO2NO2 (O(1D)+O(3P)+O3) CO H2O2 BrOx(Br+BrO) H2O² HBr NOx (NO+NO2) HOBr NOy (N + NO) BrONO2 N2O H2SO4³ N2O5 HNO3² HNO4 ClOx (Cl+ClO) Cl2O2 OClO Cl2² ClNO2² ClONO2 HCl HOCl² CH4 |
O(1D), O(3P) O3 O2* H OH HO2 NO N NO2 NO3 N2* Cl ClO Br BrO BrCl H2* CFC-11, CFC-12 |
|
² PSCs: Chipperfield, 1994 |
*constant 2-D field |
Assimilation scheme
Sequential assimilation of level 2 trace gas concentrations
at the moment only GOME ozone columns planned:
ENVISAT trace gas columns and vertical profiles.
Differences between ROSE/DLR and NCAR-ROSE
GOME ozone columns are assimilated sequentially using optimal interpolation to model-grid into the ROSE/DLR version:
A factor between the internal model ozone column and the incoming GOME total ozone measurement is derived and applied as a constant factor to the modelled ozone concentration at all vertical levels.
ROSE/DLR version 2.4 contains an empirical correction
to cope with observed altitude dependent systematic deviations between model
and measurements. ROSE/DLR ozone profiles (with assimilated GOME measurements)
vary systematically if compared with satellite and sonde measurements (see validation
page).
As a first, pragmatic approach to correct this model behaviour SAGE
II measurements are used. A height and latitude dependent factor between
ROSE/DLR ozone profiles and SAGE II measurements is calculated for four seasons.
This factor is applied to the modeled ozone profiles as a last step before the
data output. During that 'correction' the total ozone column amount is
kept constant to avoid inconsistencies in total column ozone. Comparison with
CRISTA measurements show significant improvements if the 'SAGE correction factor'
is applied.
Explanations for this model behaviour are under examination.
The horizontal resolution is set to a fixed value. Modifications are necessary for an operational use in the DLR-DFD environment. A more flexible controlling of model runs through parameter files and a different output scheme is necessary.
NCAR-ROSE
Information about the original NCAR-ROSE model version can be found on the NCAR website http://www.ncar.ucar.edu/ncar.
Papers on ROSE
Brasseur G., K. Rose, C. M. Smythe, The behavior of ozone and other trace gases in the statosphere during dynamically perturbed situations: A three-dimensional model, Ozone in the Atmosphere, R. D. Bojkov, P. Fabian (Eds.), DEEPAK Publishing, 1989, ISBN 0-937194-15-8
Riese, M., X. Tie, G. Brasseur and D. Offermann, Three-dimensional simulation of stratospheric trace gas distributions measured by CRISTA, J. Geophys. Res., 104, 16419-16435, 1999
Smolarkiewicz, P.K. and P.J. Rasch, Monotone advection on the sphere: An Eulerian versus Semi-Lagrangian approach, J. Geophys. Res., 100, 1253-1269, 1995
Please send questions, comments, ideas or criticism to Frank Baier (DLR-DFD).
