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The Portable In situ Wind ERosion Lab (PI-SWERL) was developed to measure dust emissions from soil surfaces. This small, portable unit can test the emissivity of soils in areas that are difficult to access with a field wind tunnel, and can complete a larger number of tests in less time. The PI-SWERL consists of a cylindrical enclosure containing an annular flat blade that rotates at different speeds, which generates shear stress upon the surface. The shear stress generated by PI-SWERL results in the entrainment of particles including dust. PI-SWERL was developed to provide an index of dust emission potential comparable to the field wind tunnel. The PI-SWERL dust emission results were compared against those obtained from a similar to 12 m long, 1 m wide, 0.75 m high straight line suction-type portable field wind tunnel by conducting collocated tests at 32 distinct field settings and soil conditions in the Mojave Desert of southern California. Clay-to sand-rich soils that displayed a range of crusting, gravel cover, and disturbance were tested. The correspondence between dust emissions (mg m(-2) s(-1)) for the two instruments is nearly 1: 1 on most surfaces. Deviation between the two instruments was noted for densely packed gravel surfaces. For rough surfaces a correction can be applied to the PI-SWERL that results in comparable dust emission data to the wind tunnel. PI-SWERL can be used to complement research efforts in aeolian geomorphology aimed to quantify spatial and temporal patterns of dust emissions as well as air quality research related to dust emissions.