The grid generator amatos has been developed for adaptive modeling of ocean and atmosphere circulation. It features adaptive control of planar, spherical, and volume grids with triangular or tetrahedral elements refined by bisection. The user interface (GRID API), a Fortran 90 module, shields the application programmer from the technical aspects of mesh adaptation like amatos' hierarchical data structure, the OpenMP parallelization, and the effective calculation of a domain decomposition by a space filling curve (SFC) approach. This article presents the basic structure and features of amatos, the powerful SFC ordering and decomposition of data, and two example applications, namely the modeling of tracer advection in the polar vortex and the development of the adaptive finite element atmosphere model PLASMA (parallel large scale model of the atmosphere). © 2004 Elsevier Ltd. All rights reserved.