A Test for admissibility for two-dimensional, continuous fields on planar surfaces

Radar scatterometers on oceanic satellites provide wind stress data over the oceans except for a 180° ambiguity in direction. Data sets consist of sticks, 2-dimensional vectors of known amplitude and direction, but undetermined orientation. In [1], it was shown that, for admissible stick fields, the assignment of an orientation to a single stick determines a unique realization of a vector field from the given continuous stick field. In this note, a criterion for determining admissibility of a given continuous stick field is given. This criterion depends only on the boundary curves of the region on which the stick field is given and it can be effectively checked.