At the time of the radar image, the ship is co-located with the radar in the center of the concentric rings. A red line on the reflectivity image traces the ship's path from its present location over the previous ten hours. Radially extending from the radar site on the reflectivity image, a blue line indicates the axis on which both cross-sections were taken. The radar site is always located on the left side of the cross-sections for standardization. For radial velocity, positive values indicate reflectivities moving away from the radar.
Negative values indicate reflectivities moving towards the radar.
Three criteria were employed for selecting the best axis for cross-sections. One, axes traversing areas of maximum reflectivities generally offer the most reliable data sets. Two, azimuths yielding more spatially complete data sets are favored over azimuths of greater reflectivities with less spatially complete data sets.