|KOK, JASPER - Cornell University - New York|
|MAHOWALD, NATALIE - Cornell University - New York|
|FRATINI, G - Li-Cor, Inc|
|GILLIES, J - Desert Research Institute|
|ISHIZUKA, M - Kagawa University|
|LEYS, J - Collaborator|
|MIKAMI, M - Collaborator|
|PARK, M - Seoul National University|
|PARK, S - Seoul National University|
|Van Pelt, Robert - Scott|
Submitted to: Atmospheric Chemistry and Physics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2014
Publication Date: 12/9/2014
Citation: Kok, J., Mahowald, N., Fratini, G., Gillies, J.A., Ishizuka, M., Leys, J.F., Mikami, M., Park, M.S., Park, S.U., Van Pelt, R.S., Zobeck, T.M. 2014. An improved dust emission model: Part 1: Model description and comparison against measurements. Atmospheric Chemistry and Physics. 14:13023-13041.
Interpretive Summary: Global circulation and climate models use atmospheric dust as forcers of atmospheric absorption of solar radiation and airmass heating. Current models of surface dust emissions due to wind erosion of soils are not adequately predicting the dust emissions from natural interactions of the soil surface and the atmosphere. In this paper, a new, mechanistic model of dust emission is developed that is based on soil and atmospheric parameters that are available on a global scale. The new model compares very favorably with multiple independently measured dust emission data sets. This advancement will greatly improve our ability to predict future climate changes and dust feedback effects on those changes.
Technical Abstract: Climate-induced changes in the global dust cycle are thought to have amplified past climate changes, and their potentially important role in future climate change remains unclear. Simulations of this so-called dust climate feedback are hindered by the empirical nature of existing dust flux parameterizations in models. We address this problem by presenting a physically-based theory for the dust flux that more accurately accounts for differences in soil erodibility. We show that the resulting parameterization reproduces measurements with over a factor of two less error than existing parameterizations. Moreover, the theory indicates that the sensitivity of the dust flux to the soil threshold wind speed has been substantially underestimated in models. Since the threshold wind speed varies with soil moisture, this result implies that the dust cycle is more sensitive to climate changes than previously thought. We use a global model to show that our future climate, which is predicted to have drier arid regions, will consequently be dustier than previously thought. Since dust aerosols probably produce a negative radiative forcing, the dust climate feedback is likely negative, and would thus somewhat dampen future climate changes. We provide the first estimate of the dust climate feedback due to interactions with radiation, yielding -0.03 ± 0.05 W/m2/K.