Dependence Of Radiative Forcing On Mineralogy In The Community Atmosphere Model
The mineralogy of desert dust is important due to its effect on radiation, clouds and biogeochemical cycling of trace nutrients. This study presents the simulation of dust as a function of both mineral composition and size at the global scale using mineral soil maps. Externally mixed bulk mineral aerosols in the Community Atmosphere Model version 4 (CAM4) and internally mixed modal mineral aerosols in the Community Atmosphere Model version 5.1 (CAM5) embedded in the Community Earth System Model version 1.0.3 (CESM) coordinated by the National Center for Atmospheric Research (NCAR) are speciated into common mineral components in place of total dust. The simulations with mineralogy are compared to available observations of mineral atmospheric distribution and deposition along with observations of clear-sky radiative forcing efficiency. Based on these simulations, we estimate the all-sky direct radiative forcing at the top of the atmosphere as +0.04 and +0.10 Wm-2 for CAM4 and CAM5 simulations with mineralogy and compare this with simulations of dust with optimized optical properties, wet scavenging and particle size distribution in CAM4 and CAM5 of -0.05 and -0.11 Wm-2, respectively. The ability to correctly include the mineralogy of dust in climate models is hindered by its spatial and temporal variability as well as insufficient global in-situ observations, incomplete and uncertain source mineralogies and the uncertainties associated with data retrieved from remote sensing methods.
Mahowald, Natalie M
Derry, Louis A.; Hess, Peter George Mueller
M.S. of Atmospheric Science
Master of Science
dissertation or thesis