Galactocentric radius (R_gal) and projected Rayleigh statistic (V, Eq. (4)) for the 3°× 20° × 1.29 km s⁻¹ tiles. From top to bottom, the panels correspond to each Galactic quadrant and to the whole Galactic longitude range. The colors indicate the Galactic longitude of the tiles. The horizontal dashed lines indicate V = ±2.87, which indicate the 3cc significance in the preferential orientation around θ = 0° or θ = 90°, respectively. The vertical dotted line indicates the radius of the solar orbit. The solid line in the bottom panel corresponds to the mean V values in 1-kpc R_gal bins. The vertical solid lines mark the central locations of the H I shells identified in the LAB survey (Ehlerová & Palouš 2013) and the SGPS (McClure-Griffiths et al. 2002) in the range |b| < 10°, shown in gray and green colors, respectively.