Two Maps Diverged in the Arabian Peninsula: How Mapping Soil Properties and 10m Wind Speed Impact the Mass of Dust Emitted in the GOCART Dust Emission Scheme.

Dust emission schemes have a hand in helping to accurately model many of Earth’s atmospheric processes. Dust emission is dependent on the wind and soil properties. These meteorological and physical properties are difficult to model globally. Parameterizations are used to predict and calculate large-scale values of dust emission. These parameterizations can be based on different meteorological and physical properties and in some cases produce dramatically different results, which has sweeping impacts on subsequent calculations such as radiative balance, cloud formation, biogenic process, and air quality. In this work, we examine how measurements of 10-meter wind speed from the NOAA Integrated Surface Database (ISD) and model values of 10-meter wind speed from the NASA MERRA-2 Reanalysis (Modern-Era Retrospective analysis for Research and Applications, Version 2) propagate to dust mass emitted in two leading dust emission schemes. Additionally, we look at how defining soil characteristics or topography plays a role in dust mass emitted. The first scheme is the GOCART (Goddard Chemistry Aerosol Radiation and Transport) dust emission scheme as it is used in the MERRA-2 Reanalysis - which utilizes a topographic source function. The second scheme utilizes the Sediment Supply Map (SSM) from FENGSHA (Mandarin for ‘wind-blown dust’), which defines soil properties instead of topography. The differences in wind fields and dust mass emitted are quantified on a regional scale as well as at monthly, seasonally, yearly and 20-year intervals as well as diurnally. Additional steps are taken to validate and investigate differences in AOD (Aerosol Optical Depth) due to the differences in parameterization between the GOCART topographic scheme and the FENGSHA soil properties scheme. Broadly, the ISD and MERRA-2 10-meter wind speeds disagree in magnitude and seasonality over the study region. The topographic source function and SSM show similar patterns of positive and negative differences compared to the MERRA-2 Reanalysis. However, the topographic source exhibits smaller values of dust emission in the Middle East compared to the SSM by an order of magnitude in many of the cases discussed here. Similarly, variability in the mass of dust emitted by year and season in both the SSM and topographic source is explored. AOD is discussed in relation to the flux values as calculated by both schemes. Physical reasoning for qualitative and quantitative results are discussed.