Variation in the volumetric power and momentum losses in the JET-ILW scrape-off layer

•A large variation in the scrape-off layer momentum and power losses has been demonstrated on JET with the ITER-like wall.•Observations provide key insights into the dependence of volumetric losses on the dominant dissipation mechanisms, whether due to neutral-plasma interactions, impurity radiation induced detachment, and their interplay.•In pure deuterium L-mode density ramps, a relatively constant target heat flux response is observed above a target electron temperature (Te,t) of 5 eV, where the decrease in Te,t is balanced by a rise in target pressure.•Conversely, the onset of momentum losses in L-mode nitrogen seeding scans in low recycling conditions occurs at high Te,t = 10 eV, leading to a more pronounced reduction in the target heat flux.•The results confirm the theoretical and code predictions that both volumetric loss processes are required for detachment.