  In this paper, we extend the calculation of the atmospheric neutrino
flux~\cite{hkkm2004,hkkms2006,hkkm2011} to the sites in polar and tropical
regions. In our earliest full 3D-calculation~\cite{hkkm2004}, we used
DPMJET-III~\cite{dpm} for the hadronic interaction model above 5~GeV, and
NUCRIN~\cite{nucrin} below 5~GeV. We modified DPMJET-III as in
Ref.~\cite{hkkms2006} to reproduce the experimental muon spectra better, mainly
using the data observed by BESS group~\cite{BESSTeVpHemu}. In a recent
work~\cite{hkkm2011}, we introduced JAM interaction model for the low energy
hadronic interactions. JAM is a nuclear interaction model developed with PHITS
(Particle and Heavy-Ion Transport code System)~\cite{phits}. In
Ref.~\cite{hkkm2011}, we could reproduce the observed muon flux at the low
energies at balloon altitude with DPMJET-III above 32 GeV and JAM below that
better than the combination of DPMJET-III above 5~GeV and NUCRIN below that.
Besides the interaction model, we have also improved the calculation scheme
according to the increase of available computational power, such as the
"virtual detector correction" introduced in Ref.~\cite{hkkms2006} and the
optimization of it in Ref.~\cite{hkkm2011}. The statistics of the Monte Carlo
simulation is also improved at every step of the work.
