Downscaling CESM2 in CLM5 to Hindcast Pre-Industrial Equilibrium Line
Altitudes for Tropical Mountain Glaciers
Abstract
Tropical mountain glaciers are an important water resource and highly
impacted by recent climate change. Tropical mountain glaciation also
occurred in the recent and deep past, which presents opportunities for
better validating paleoclimate simulations in continental interiors and
mountainous regions but requires bridging global model scales (100s of
km) with the ~ 1–10 km scale of glaciers when
paleotopography is poorly known. Here we hindcast tropical mountain
glaciation in pre-industrial time by using global climate model
meteorology to force standalone simulations in its land component that
use high resolution topography to resolve selected tropical mountain
glaciers. These simulations underestimate observed equilibrium line
altitudes (ELA) by 249 ± 330 m, but the simulated ELA and snow lines
capture observed inter-mountain ELA variability. Error in large-scale
model precipitation and ELA reconstruction uncertainty are the main
contributors to this bias.