Atmospheric neutrinos - present and future -

Atmospheric neutrinos have been playing a major role in studying neutrino oscillations. The present data are consistent with pure 2 flavor νμ→ντ oscillations. The allowed νμ→ντ oscillation parameter region is sin22θ23>0.92 and 1.5<Δm232<3.4×10−3eV2 at 90%C.L. Recent data from an L/E analysis showed that the νμ disappearance probability obeys the sinusoidal function as predicted by neutrino oscillations. Future atmospheric neutrino experiments are also discussed emphasizing the measurement of θ13 and the sign of Δm232.