Lagrangian transport experiments in the MLT region

In order to evaluate material transports in the upper mesosphere and lower thermosphere (MLT) region, Lagrangian transport experiments are performed using wind fields simulated by the Kyushu University middle atmosphere general circulation model (Miyahara and Miyoshi, 1997; Miyahara et al., 1993). The Lagrangian mean meridional circulation is different from the residual mean circulation defined by the Transformed Eulerian Mean equation system, which is thought to be approximately equal to the Lagrangian mean meridional circulation in the middle atmosphere in case of weak dissipation and transience (Andrews and McIntyre, 1978; Andrews et al., 1987). It is considered that the diffusivity caused by the transience and dissipation of various wave motions in the MLT region has significant effects on the material transport in this region, and makes them different from each other.