Integrated Terrain Analysis Program Field Equipment

Visual Surface Roughness Look-up Table for PI-SWERL Measurements

Below is a database of surface roughness of emissive desert landforms. The surface roughness parameter, alpha (α), has been calculated directly from a high-resolution microtopographic Digital Elevation Model. Visual comparison of high-resolution images alongside calculated α values are compiled here for commonly encountered field surfaces. These are presented as a new look-up table for assigning α values to field surfaces for correcting PI-SWERL measurements for surface roughness, expanding on the look-up table of Etyemezian et al. (2014). Consistent visual comparison to these surfaces when assigning alpha will remove some of the subjectivity in assigning α values, further constraining an important source of error that exists in current PI-SWERL methodology.

Any use of this database should be cited as follows:
Hartshorn, E., Sion, B., Sweeney, M., and McDonald, E., revised 2023, Visual Surface Roughness Look-up Table for PI-SWERL Measurements,

Any questions should be directed towards

Click on any of the drop-down items below for more information.

Playas: Polygonal

Playas: Salt-Crusted

Playas: Deflated and Aggregates

Playa Fringes

Alluvial Fans and Floodplains

Sand Dune and Sand Sheet

Active Washes


Brad Sion, Ph.D.
Program Director


Desert Research Institute
2215 Raggio Parkway
Reno, NV 89512


Earth & Ecosystem Sciences