  We investigate the origin of the $\mathrm{Br}\gamma$ emission of the Herbig
Ae star HD104237 on Astronomical Unit (AU) scales. Using AMBER/VLTI at a
spectral resolution R=1500 spatially resolve the emission in both the BrGamma
line and the adjacent continuum. The visibility does not vary between the
continuum and the BrGamma line, even though the line is strongly detected in
the spectrum, with a peak intensity 35% above the continuum. This demonstrates
that the line and continuum emission have similar size scales. We assume that
the K-band continuum excess originates in a ``puffed-up'' inner rim of the
circumstellar disk, and discuss the likely origin of BrGamma. We conclude that
this emission most likely arises from a compact disk wind, launched from a
region 0.2-0.5 AU from the star, with a spatial extent similar to that of the
near infrared continuum emission region, i.e, very close to the inner rim
location.
