Stratospheric HTO and 95Zr residence times

The depletion of the stratospheric burdens of particulate 95Zr for times up to around 1 year, and gaseous HTO for times up to 3 years, attributed to the November 17, 1976 Chinese high-yield test indicates that both have about the same residence half-time (10 months). The indications are that gravitational settling of particles in the lower stratosphere can be considered to be negligible in studying transport processes. The rate of depletion of the stratospheric burden of HTO from the high-yield Chinese test of June 27, 1973 is not as well-defined in part due to greater uncertainties in calculating the stratospheric burdens.