Representing Vegetation with Ecosystem Functional Types in WRF Simulations

OMAR V. MÜLLER; ERNESTO H. BERBERY

Boulder, CO, USA

Workshop; 13th Annual WRF Users' Workshop; 2012

Land surface processes vary from energy and water exchange with the atmosphere on short time scales to changes in soil moisture, vegetation structure and phenology on longer timescales. However, WRF model represents vegetation with land cover types fixed in time. Hence, they are insensitive to any vegetation variability.In order to include biosphere processes and their effects over the atmosphere, we examine the advantages of using Ecosystem Functional Types (EFTs) as a replacement of conventional land cover types. EFTs are groups of ecosystems that share functional characteristics in relation to the exchanges of matter and energy between the biota and the physical environment. EFTs are defined on a yearly basis, therefore, they can reproduce vegetation changes resulting from either land use or natural changes.Long-term simulations with conventional land cover representation were compared with simulations using EFTs as lower boundary conditions during the drought of 2008 in southestern South America. The results show the model sensitivity to vegetation variability, reducing the precipitation bias over the drought region and another region of large precipitation to the north. This suggests that a better representation of surface processes could enhance the system predictability.