  In this paper, we analyzed 12 years of Fermi LAT gamma-ray data towards three
nearby giant molecular clouds (GMCs), i.e., R~CrA, Chamaeleon, and Lupus. We
calibrated the gas column density of these regions by using the Planck dust
opacity map as well as the Gaia extinction map. With both the gamma-ray
observations and gas column density maps, we derived the cosmic ray densities
in the three GMCs. We found the derived CR spectra have almost the same shape
but significantly different normalizations, which may reflect that the
distributions of CRs in the vicinity of solar systems are inhomogeneous.
