  The Space Weather program of the Latin American Giant Observatory (LAGO)
Collaboration was designed to study the variation of the flux of atmospheric
secondary particles at ground level produced during the interaction of cosmic
rays with the air. This work complements and expands the inference capabilities
of the LAGO detection network to identify the influence of solar activity on
the particle flux, at places having different geomagnetic rigidity cut-offs and
atmospheric depths. This program is developed through a series of Monte Carlo
sequential simulations to compute the intensity spectrum of the various
components of the radiation field on the ground. A key feature of these
calculations is that we performed detailed radiation transport computations as
a function of incident direction, time, altitude, as well as latitude and
longitude. Magnetic rigidity calculations and corrections for geomagnetic field
activity are established by using the MAGNETOCOSMICS code, and the estimation
of the flux of secondaries at ground level is implemented by using the CORSIKA
code; thus we can examine the local peculiarities in the penumbral regions with
a more realistic description of the atmospheric and geomagnetic response in
these complex regions of the rigidity space. As an example of our calculation
scheme, we report some result on the flux at ground level for two LAGO
locations: Bucaramanga-Colombia and San Carlos de Bariloche-Argentina, for the
geomagnetically active period of May 2005.
