momentumRoughnessLength: Calculates Momentum Roughness Length

Description Usage Arguments Details Author(s) References


this function estimates Momentum Roughness Length (Zom) from the average vegetation height around the weather station.


momentumRoughnessLength(method = "short.crops", LAI, NDVI, albedo, a, b,
  fLAI.Perrier, h.Perrier, mountainous = FALSE, surface.model)



method selected to calculate momentum roughness length. Use "short.crops" for short crops methods from Allen et al (2007); "custom" for custom method also in Allen et al (2007); Or "Perrier" to use Perrier equation as in Santos et al (2012) and Pocas et al (2014).


rasterLayer with Leaf Area Index. See LAI(). Only needed for method = "short.crops"


rasterLayer with Normalized Difference Vegetation Index. Only needed for method = "custom"


broadband surface albedo. See albedo()


"a" coefficients for Allen (2007) custom function to estimate Momentum roughness length. Only needed for method = "custom"


"b" coefficients for Allen (2007) custom function to estimate Momentum roughness length. Only needed for method = "custom"


proportion of LAI lying above h/2. Only needed for method = "Perrier"


crop height in meters. Only needed for method = "Perrier"


empirical adjustment for effects of general terrain roughness on momentum and heat transfer. See Allen (2007)


surface model with a RasterLayer called "Slope" needed is mountainous = TRUE. See surface.model()


According Allen et al,. 2010 Zom is a measure of the form drag and skin friction for the layer of air that interacts with the surface.


Guillermo Federico Olmedo

de la Fuente-Saiz, Daniel


R. G. Allen, M. Tasumi, and R. Trezza, "Satellite-based energy balance for mapping evapotranspiration with internalized calibration (METRIC) - Model" Journal of Irrigation and Drainage Engineering, vol. 133, p. 380, 2007

Pocas, I., Paco, T.A., Cunha, M., Andrade, J.A., Silvestre, J., Sousa, A., Santos, F.L., Pereira, L.S., Allen, R.G., 2014. Satellite-based evapotranspiration of a super-intensive olive orchard: Application of METRIC algorithms. Biosystems Engineering 128, 69-81. doi:10.1016/j.biosystemseng.2014.06.019

Santos, C., Lorite, I.J., Allen, R.G., Tasumi, M., 2012. Aerodynamic Parameterization of the Satellite-Based Energy Balance (METRIC) Model for ET Estimation in Rainfed Olive Orchards of Andalusia, Spain. Water Resour Manage 26, 3267-3283. doi:10.1007/s11269-012-0071-8

Search within the water package
Search all R packages, documentation and source code

Questions? Problems? Suggestions? or email at

Please suggest features or report bugs with the GitHub issue tracker.

All documentation is copyright its authors; we didn't write any of that.