The Princess Sirindhorn Neutron Monitor at Doi Inthanon, Thailand provides important information about high-energy cosmic rays from space. Both the neutron monitor (NM) and Bare (lead-free) neutron counters detect the variation of intensity in the interplanetary cosmic rays. In addition, the bare detector to neutron monitor count rate ratio (Bare/NM) provides information on the particle spectrum. We found that variation in Bare/NM is strongly anti-correlated with atmospheric water vapor (Ew) as inferred from the Global Atmospheric Data Assimilation (GDAS). In the present work, we develop a correction to Bare/NM for water vapor pressure. The results of comparison of the Ew from the GDAS database with another database will be discussed.