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The impact of the height of the model top on the simulation of tropospheric stationary waves
Author(s) -
Ruosteenoja Kimmo
Publication year - 1999
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49712555415
Subject(s) - troposphere , forcing (mathematics) , atmospheric sciences , northern hemisphere , climatology , latitude , environmental science , atmosphere (unit) , southern hemisphere , middle latitudes , geology , meteorology , physics , geodesy
Wintertime stationary waves in the northern hemisphere were simulated with a linear model, employing an observational zonal‐mean state and recent estimates for thermal damping. the sensitivity of the simulations to the height of the model top, which was varied between 0.1 and 100 hPa, proved to be much smaller than in previous research. As long as the model top was located at 10 hPa or higher, the tropospheric stationary waves were well simulated, the correlation with the observed pattern at various levels being ∼ 0.8 or higher. Lowering the top to 30 or 100 hPa reduced the correlation by less than 0.1 units in the upper troposphere, and by even less near the surface. In an experiment with a local idealized high‐latitude forcing, the response was somewhat more sensitive to the placement of the top. Eliassen‐Palm fluxes proved an excellent tool in tracing the influence of the top on wave propagation. the distribution of the fluxes shows that the interaction with the model top takes place mainly in the extratropics, irrespective of the latitude of the forcing. Applying a sponge layer with artificially enhanced damping near the top improved the solution significantly in most of the experiments in which the top was located at 30 hPa or lower.