Effective aerodynamic roughness estimated from airborne laser altimeter measurements of surface features

TitleEffective aerodynamic roughness estimated from airborne laser altimeter measurements of surface features
Publication TypeJournal Article
Year of Publication2003
AuthorsDe Vries A.C, Kustas WP, Ritchie J, Klaassen W., Menenti M., Rango A., Prueger J.H.
JournalInternational Journal of Remote Sensing
Date PublishedApril 10, 2003
Accession NumberJRN00383
ARIS Log Number157712
Keywordsaerodynamic roughness, airborne laser altimeter, measurements, surface features

Aerodynamic roughness length (z0) and displacement height (d0) are important surface parameters for estimating surface fluxes in numerical models. These parameters are generally determined from wind flow characteristics using logarithmic wind profiles measured at a meteorological tower or by balloon release. It would be an advantage to use measurements of land surface characteristics instead of wind flow characteristics to estimate the z0 and d0 for large areas. Important land surface characteristics are the size and distribution of roughness elements (obstacles). This research evaluates the use of high resolution laser altimeter data to obtain these land surface characteristics. Data were collected at the US Department of Agriculture, Agriculture Research Service (USDA-ARS), Jornada Experimental Range in southern New Mexico, USA over a coppice dune dominated area. These dunes are covered by honey mesquite (Prosopis glandulosa Torr.) with flat and mostly bare interdunal areas. For this analysis, three 450 m laser transects with a 2 cm measurement interval were used. The distribution and size of dunes were calculated from these laser transects and used to compute z0. Analysis gave an average z0=4.3 cm and d0=70 cm for the three laser transects, which compares to z0=7+4cm and d0=98+48 cm calculated from wind profile data measured at a 10 m tower near the laser transects. These results show that the estimation of z0 and d0 for a complex terrain is possible using simple land surface features computed from high resolution laser altimeter data.