Measurements of Freshly Emitted Dust Size Distributions made with a Cloud Droplet Probe in the Sonoran Desert Suggest Larger Particle Sizes than Predicted by Theory

Here we present new size distribution measurements of freshly emitted dust in a portion of the Sonoran Desert located in southeastern California. Measurements were made with a Droplet Measurements Technology Cloud Droplet Probe, which is a water droplet spectrometer that has a nominal size range of 2 to 50 𝜇m. However, after correction for the dust refractive index, which we obtain from measurements made with the AVIRIS instrument, this range spans approximately 1 to 90 𝜇m. Comparisons are made between the measured size and volume distributions with that from theory. From these comparisons we find that even an updated version of the dust size distribution given by brittle fragmentation theory that accounts for large particles still underestimates concentrations of supercoarse particles by several orders magnitude. We present plans for future work aimed at making new measurements that are more representative of the emitted size distribution. Our area of interest is near the Salton Sea, California's largest inland body of water, which is rapidly shrinking due to changes in water management practices. As such, this area and these results are also relevant in terms of understanding the rapid environmental change happening in the region.