Idealized simulations of orographic precipitation across complex, evolving topography

Precipitation gradients across large-scale complex topography play a central role in the hydroclimatology of mountainous regions. On geological time-scales, topography can change due to tectonic processes, with associated upstream and downstream influences on precipitation. However, there are few quantitative constraints on the sensitivity of precipitation gradients to topography and atmospheric conditions, or on the impact of evolving topography on precipitation gradients. Idealized WRF simulations of orographic precipitation over two-dimensional valley-ridge topography show that 800 m of ridge uplift increases precipitation at the uplifting ridge by a factor of ten, and that even just 200 m of ridge uplift can double the precipitation over the ridge. Small changes in topography also have a large impact on precipitation both upstream and downstream of the uplifting ridge. Furthermore, uniform changes in the initial atmospheric state induce nonuniform changes in precipitation across the idealized mountain range.