Shell representations for flux and temperature at the time of a maximum DS of 20 m/s. The masked shell is defined as the element-wise product between the spectral shell and the associated density-weight map. In the shell construction, a cell is assigned zero only when no spectral pixels populate the corresponding bin. Although the same selected spectral pixels are used for both the flux- and temperature-based shells, they are projected onto different shell spaces, (F, ∂F/∂v) and (T, ∂T/∂v), so the occupancy of the shell cells is not identical between the two representations. Top row: Flux representations, with the first two panels unmasked and the last two masked. Bottom row: Same configuration for the temperature-based representation.