WRFv3.2-SPAv2: development and validation of a coupled ecosystem–atmosphere model, scaling from surface fluxes of COsub2/sub and energy to atmospheric profiles

摘要

The Weather Research and Forecasting meteorological (WRF) model has beencoupled to the Soil–Plant–Atmosphere (SPA) terrestrial ecosystem model, toproduce WRF-SPA. SPA generates realistic land–atmosphere exchanges throughfully coupled hydrological, carbon and energy cycles. The addition of a~landsurface model (SPA) capable of modelling biospheric CO₂ exchange allowsWRF-SPA to be used for investigating the feedbacks between biosphere carbonbalance, meteorology, and land use and land cover change. We have extensivelyvalidated WRF-SPA using multi-annual observations of air temperature,turbulent fluxes, net radiation and net ecosystem exchange of CO₂ at threesites, representing the dominant vegetation types in Scotland (forest,managed grassland and arable agriculture). For example air temperature iswell simulated across all sites (forest R2 = 0.92,RMSE = 1.7 °C, bias = 0.88 °C; managed grasslandR2 = 0.73, RMSE = 2.7 °C, bias = ?0.30 °C;arable agriculture R2 = 0.82, RMSE = 2.2 °C,bias = 0.46 °C; RMSE, root mean square error). WRF-SPA generatesmore realistic seasonal behaviour at the site level compared to an unmodifiedversion of WRF, such as improved simulation of seasonal transitions in latentheat flux in arable systems. WRF-SPA also generates realistic seasonal CO₂exchanges across all sites. WRF-SPA is also able to realistically modelatmospheric profiles of CO₂ over Scotland, spanning a 3 yr period(2004–2006), capturing both profile structure, indicating realistictransport, and magnitude (model–data residual <±4 ppm) indicatingappropriate source sink distribution and CO₂ exchange. WRF-SPA makes useof CO₂ tracer pools and can therefore identify and quantify land surfacecontributions to the modelled atmospheric CO₂ signal at a specifiedlocation.