Impacts of Aerosol Shortwave Radiation Absorption on the Dynamics of an Idealized Convective Atmospheric Boundary Layer
| Autor: | Maarten Krol, Albert A. M. Holtslag, Eduardo Barbaro, J. Vilà-Guerau de Arellano |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Convection
Meteorologie en Luchtkwaliteit Atmospheric Science 010504 meteorology & atmospheric sciences Meteorology and Air Quality Planetary boundary layer entrainment Stratification (water) 010501 environmental sciences Sensible heat Atmospheric sciences 01 natural sciences closure-model Potential temperature surface climate Physics::Atmospheric and Oceanic Physics 0105 earth and related environmental sciences actinic flux WIMEK turbulence simulation Aerosol photolysis 13. Climate action Heat transfer Turbulence kinetic energy Environmental science heating rates energy-budget |
| Zdroj: | Boundary-Layer Meteorology, 148(1), 31-49 Boundary-Layer Meteorology 148 (2013) 1 Boundary-Layer Meteorology |
| ISSN: | 0006-8314 |
| Popis: | We investigated the impact of aerosol heat absorption on convective atmospheric boundary-layer (CBL) dynamics. Numerical experiments using a large-eddy simulation model enabled us to study the changes in the structure of a dry and shearless CBL in depth-equilibrium for different vertical profiles of aerosol heating rates. Our results indicated that aerosol heat absorption decreased the depth of the CBL due to a combination of factors: (i) surface shadowing, reducing the sensible heat flux at the surface and, (ii) the development of a deeper inversion layer, stabilizing the upper CBL depending on the vertical aerosol distribution. Steady-state analytical solutions for CBL depth and potential temperature jump, derived using zero-order mixed-layer theory, agreed well with the large-eddy simulations. An analysis of the entrainment zone heat budget showed that, although the entrainment flux was controlled by the reduction in surface flux, the entrainment zone became deeper and less stably stratified. Therefore, the vertical profile of the aerosol heating rate promoted changes in both the structure and evolution of the CBL. More specifically, when absorbing aerosols were present only at the top of the CBL, we found that stratification at lower levels was the mechanism responsible for a reduction in the vertical velocity and a steeper decay of the turbulent kinetic energy throughout the CBL. The increase in the depth of the inversion layer also modified the potential temperature variance. When aerosols were present we observed that the potential temperature variance became significant already around $$0.7z_i$$ (where $$z_i$$ is the CBL height) but less intense at the entrainment zone due to the smoother potential temperature vertical gradient. |
| Databáze: | OpenAIRE |
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