Lagrangian decomposition of the Hadley Cells
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
The Lagrangian trajectory code TRACMASS is extended to the atmosphere to examine the tropi- cal Hadley Cells using fields from the ERA-Interim reanalysis dataset. The analysis is made using both pressure, temperature and specific humidity as vertical coordinates. By letting a trajectory represent a mass transport and tracing millions of trajectories in a domain between the latitudes 15°N and 15°S, the mass stream function based on trajectories is obtained (Lagrangian stream function). By separating the trajectories into classes depending on their starting point and des- tination (“North-to-North”, “North-to-South”, “South-to-North” and “South-to-South”), the mass stream function is decomposed into four paths. This can not be done if the stream function is cal- culated directly from the velocity fields (Eulerian stream function). Using this technique, the mass transports recirculating within the cells are compared to the mass transports between the cells, giving further insight to the structure of the Hadley Circulations.
The magnitudes of the mass stream functions are presented by converting the volume flux unit Sverdrup into a mass flux unit. It is found that the recirculating transports of the northern and southern cells are 473 Sv and 508 Sv respectively. The inter-hemispheric mass transports are 126 Sv northward and 125 Sv southward. It is also found that far from all trajectories follow paths sim- ilar to the stream lines, since the stream lines are zonal and temporal means and the particle trajectories chaotic.
Place, publisher, year, edition, pages
2009. , 37 p.
Lagrangian decomposition, Hadley, TRACMASS, trajectory streamfunction
Meteorology and Atmospheric Sciences
IdentifiersURN: urn:nbn:se:su:diva-87324OAI: oai:DiVA.org:su-87324DiVA: diva2:602584
2009-06-03, C609, Svante Arrhenius väg 16C, Stockholm, 16:13 (Swedish)
UppsokPhysics, Chemistry, Mathematics
Döös, Kristofer, Professor
Svensson, Gunilla, Professor