Figure 7 . Sensitivity analysis where initial conditions use
final rainfall patterns from Case 3 (a) and Case 4 (b), and examples
from the eastern flank of the Peruvian Andes (c) and eastern-central
Himalaya (d). Panel layouts are the same as in Figure 3b. Triangular
fields in demarcated in black dashes in (a) and (b) bound rainfall
gradients with the same pattern as the initial condition (i.e.,
bottom-heavy or top-heavy), but cause complex transient responses
similar to those expected for reversals in polarity of the rainfall
pattern as the rainfall becomes relatively bottom- or top-heavy
– see section 5.1 for further discussion. Panels (c & d) show examples
of climate change scenarios from model simulations reported in
supplementary tables by Mutz et al. (2018), for a hypothetical
transverse river with parameters in Table 1. Initial condition is set in
the Pliocene (PLIO), and representative evolution of the orographic
rainfall pattern through to the Last Glacial Maximum (LGM) is plotted,
illustrating that climate changes that are predicted to trigger complex
responses are likely not uncommon.