Aims Combining field data analysis and modeling,this study investigates factors influencing the diurnal boundary layer(BL)development in boreal forest.Methods Field data analysis used both air sounding and surface flu...Aims Combining field data analysis and modeling,this study investigates factors influencing the diurnal boundary layer(BL)development in boreal forest.Methods Field data analysis used both air sounding and surface flux measurements collected during the Boreal Ecosystem–Atmosphere Study field campaigns in central Canada.Model study applied a non-local transilient turbulence theory(TTT)to simulate the impact of the heterogeneous boundary conditions together with initial conditions on the BL development at the Candle Lake and Thompson release sites over boreal forests.Boundary conditions were characterized by the integrated surface flux measurements from different forest stands.The lake effect was included in constructing the surface fluxes at Candle Lake release site.Important Findings Analyses of serial upper air sounding data and tower flux data indicate strong linear impacts of surface sensible heat forcing on the diurnal BL development above boreal forests.The regression slopes on the relationship between the BL development and the surface fluxes reflect the influences of initial boundary conditions to the BL developments.Both the modeled and the measured diurnal BLs show that lakes reduce sensible heat flux,leading to a shallower boundary in Candle Lake than in Thompson.Comparison of the model results and field measurements on the BL profiles indicates that the TTT model has the capability to simulate the BL development above boreal forests for sunny,rainfall or cloudy days.This study demonstrates the importance of lake on surface fluxes and BL development.The modeling effort shows the potential to couple the transilient theory with a land surface process model to study land surface and atmosphere interaction in boreal forest.展开更多
基金The National Aeronautics and Space Administration(NASA)(NNG05GE01G).
文摘Aims Combining field data analysis and modeling,this study investigates factors influencing the diurnal boundary layer(BL)development in boreal forest.Methods Field data analysis used both air sounding and surface flux measurements collected during the Boreal Ecosystem–Atmosphere Study field campaigns in central Canada.Model study applied a non-local transilient turbulence theory(TTT)to simulate the impact of the heterogeneous boundary conditions together with initial conditions on the BL development at the Candle Lake and Thompson release sites over boreal forests.Boundary conditions were characterized by the integrated surface flux measurements from different forest stands.The lake effect was included in constructing the surface fluxes at Candle Lake release site.Important Findings Analyses of serial upper air sounding data and tower flux data indicate strong linear impacts of surface sensible heat forcing on the diurnal BL development above boreal forests.The regression slopes on the relationship between the BL development and the surface fluxes reflect the influences of initial boundary conditions to the BL developments.Both the modeled and the measured diurnal BLs show that lakes reduce sensible heat flux,leading to a shallower boundary in Candle Lake than in Thompson.Comparison of the model results and field measurements on the BL profiles indicates that the TTT model has the capability to simulate the BL development above boreal forests for sunny,rainfall or cloudy days.This study demonstrates the importance of lake on surface fluxes and BL development.The modeling effort shows the potential to couple the transilient theory with a land surface process model to study land surface and atmosphere interaction in boreal forest.
