Evident cooling effects of surface wetlands to mitigate climate change -
a study of the Prairie Pothole Region
Abstract
Wetlands are an important land type – they provide vital ecosystem
services such as regulating floods, storing carbon, and providing
wildlife habitat. The ability to simulate their spatial extent and
hydrological processes is important for valuing wetlands’ function. The
purpose of this study is to dynamically simulate wetlands’ hydrological
processes and their feedback to the regional climate in the Prairie
Pothole Region (PPR) of North America, where a large number of wetlands
exist. In this study, we incorporated a wetland scheme into the Noah-MP
Land Surface Model with two major modifications: (1) modifying the
sub-grid saturation fraction for spatial wetland extent; (2)
incorporating a dynamic water storage to simulate hydrological
processes. This scheme was tested at a fen site in central Saskatchewan,
Canada and applied regionally in the PPR with 13-year climate forcing
produced by a high-resolution convection-permitting model. The
differences between wetland and no-wetland simulations are significant,
with increasing latent heat and evapotranspiration while decreasing
sensible heat and runoff. Finally, the dynamic wetland scheme was tested
using the coupled WRF model, showing an evident cooling effect of
1~3℃ in summer where wetlands are abundant. In
particular, the wetland simulation shows reduction in the number of hot
days for more than 10 days over the summer of 2006, when a long-lasting
heatwave occurred. This research has great implications for land
surface/regional climate modeling, as well as wetland conservation, for
valuing wetlands in providing a moisture source and mitigating extreme
heatwaves, especially under climate change.