Establishing the Large Scale Geomorphological Signature of Dust Emissions
1, Paul Ginoux2, Joanna Bullard1, Thomas Gill3
1Loughborough University, Loughborough, Leicestershire, UK, 2NOAA Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA, 3University of Texas at El Paso, El Paso, Texas, USA
The Preferential Dust Source (PDS) scheme is a land surface classification scheme that has been developed to enable large scale mapping of geomorphology in terms of its importance for dust emissions. The ability of this classification to actually represent dust emission however has not been independently evaluated other than at local scales. Here, we examine the PDS scheme as a qualitative conceptual model of surface emissivity against a quantitative measurement of remotely sensed dust loading (MODIS Deep Blue Collection 6) for a major dust source region in North America - the Chihuahuan Desert. The predicted ranked importance of each geomorphic type for dust emissions is compared with the actual ranked importance as determined from the long term satellite dust loading. For the Chihuahuan Desert, the predicted variability and magnitude of dust emissions from most surface types coincides with the observed characteristics, clearly demonstrating the significance of geomorphological controls on emission (e.g., the preferential nature of ephemeral lakes). The exception is for areas of low magnitude but persistent emissions such as alluvial surfaces where PDS is found to over-predict dustiness. Overall, PDS emerges as a good predictor of dust emissions at a broad scale, and by inherently incorporating the dynamics of land surface types (e.g. susceptibility to flooding, frequency of sediment supply), PDS could be used to improve models of future dust emissions.