Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 3 4 1999 10.5194/hess-3-549-1999 http://www.hydrol-earth-syst-sci.net/3/549/1999/ http://www.hydrol-earth-syst-sci.net/3/549/1999/hess-3-549-1999.html http://www.hydrol-earth-syst-sci.net/3/549/1999/hess-3-549-1999.pdf 549 563 0000-00-00 Aggregation effects of surface heterogeneity in land surface processes Z. Su H. Pelgrum M. Menenti Wageningen UR, ALTERRA Green World Research, P.O. Box 47, 6700 AA Wageningen e-mail address for corresponding author: su@sc.dlo.nl In order to investigate the aggregation effects of surface heterogeneity in land surface processes we have adapted a theory of aggregation. Two strategies have been adopted: 1) Aggregation of radiative fluxes. The aggregated radiative fluxes are used to derive input parameters that are then used to calculate the aerodynamic fluxes at different aggregation levels. This is equivalent to observing the same area at different resolutions using a certain remote sensor, and then calculating the aerodynamic fluxes correspondingly. 2) Aggregation of aerodynamic fluxes calculated at the original observation scale to different aggregation levels. A case study has been conducted to identify the effects of aggregation on areal estimates of sensible and latent heat fluxes. The length scales of surface variables in heterogeneous landscapes are estimated by means of wavelet analysis.