We use data from the Radial Velocity Experiment ( RAVE ) and the Tycho-Gaia astrometric solution catalogue ( TGAS ) to compute the velocity fields yielded by the radial ( V _ { R } ) , azimuthal ( V _ { \phi } ) and vertical ( V _ { z } ) components of associated Galactocentric velocity .
We search in particular for variation in all three velocity components with distance above and below the disc midplane , as well as how each component of V _ { z } ( line-of-sight and tangential velocity projections ) modifies the obtained vertical structure .
To study the dependence of velocity on proper motion and distance we use two main samples : a RAVE sample including proper motions from the Tycho -2 , PPMXL and UCAC4 catalogues , and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues .
In both samples , we identify asymmetries in V _ { R } and V _ { z } .
Below the plane we find the largest radial gradient to be \partial V _ { R } / \partial R = -7.01 \pm 0.61 km s ^ { -1 } kpc ^ { -1 } , in agreement with recent studies .
Above the plane we find a similar gradient with \partial V _ { R } / \partial R = -9.42 \pm 1.77 km s ^ { -1 } kpc ^ { -1 } .
By comparing our results with previous studies , we find that the structure in V _ { z } is strongly dependent on the adopted proper motions .
Using the Galaxia Milky Way model , we demonstrate that distance uncertainties can create artificial wave-like patterns .
In contrast to previous suggestions of a breathing mode seen in RAVE data , our results support a combination of bending and breathing modes , likely generated by a combination of external or internal and external mechanisms .