| 1. |
- Kjellsson, Joakim, 1986-, et al.
(author)
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Lagrangian decomposition of the Hadley and Ferrel cells
- 2012
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In: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 39, s. L15807-
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Journal article (peer-reviewed)abstract
- The meridional overturning circulation of the atmosphere between 45°S and 45°N is decomposed using simulated 3D Lagrangian trajectories for calculating the Lagrangian overturning streamfunctions. This permits an analysis of meridional mass transports which otherwise cancel in time-averaged zonal-mean Eulerian streamfunctions. Overturning circulations inferred from trajectories of no net meridional transport are qualitatively similar to the Eulerian mean, but yield half the Hadley cell amplitude, and twice that of the Ferrel cell. Cross-equatorial transports of some 130 Sv result in two cells that account for the remainder of the Hadley cells. The overturning in midlatiudes is partly cancelled by large (≈150 Sv) meridional transports approximately following isentropes. Changes and implications for various coordinate systems, e.g., isentropic, are also discussed.
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| 2. |
- Kjellsson, Joakim, 1986-, et al.
(author)
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Surface drifters and model trajectories in the Baltic sea
- 2012
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In: Boreal environment research. - 1239-6095 .- 1797-2469. ; 17:6, s. 447-459
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Journal article (peer-reviewed)abstract
- Results from recent deployments of surface drifters in the Baltic Sea are presented. For the first time ever, the realism of model-generated trajectories was assessed by a statistical com- parison with trajectories of SVP drifters. The absolute dispersion (i.e. the distance from the initial point as a function of time) was found to be somewhat underestimated by the model trajectories. A severe underestimation of the relative dispersion (pair separation) was also noted, which may, to some extent, be due to the limited resolution of the model. However, the relative dispersion was also found to be very dependent on the initial separation of the model trajectory pairs. After filtering the inertial oscillations, a good agreement of the veloc- ity auto-correlations between the drifters and model trajectories was found. A discussion on the impact of these results on future trajectory modelling in the Baltic Sea is also provided.
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