Atmospheric effects on the underground muon intensity

It has previously been reported that the barometric pressure coefficient observed for muons at Poatina (vertical absorber depth 357 hg/sq cm) appears to be appreciably higher than would be expected from atmospheric absorption alone. There is a possibility that the effect is due to an upper atmospheric temperature effect arising from an inverse correlation of surface pressure with stratospheric temperature. A new proportional telescope is discussed which has been operating at Poatina since about the beginning of 83 and which has a long term stability suitable for studying variations of atmospheric origin.