Question

Derive relationship between ionic conductance and ionic mobility

Answer 1

The measurements of the mobility and concentration of ions and the ionic conductivity in the lower stratosphere are reviewed. The measurements are made from rocket, parachute, and balloon platforms. The typical mass of the ions inferred from rocket and parachute platform measurements of the ionic mobilities is ∼30 amu or lower, while that from a balloon platform measurement is ∼1000 amu. Recent in situ ion measurements made at ∼35 km with mass spectrometers on balloon platforms indicate that ion masses as high as ∼140 amu and ∼300 amu for the positive and negative ions, respectively, are present. The ion masses obtained from direct and inferred measurements on rocket platforms are therefore significantly lower than those obtained with balloon platforms. The positive ion concentrations measured from rocket and parachute platforms during quiet times are generally lower than those predicted from a cosmic ray ionization source, while those made from the balloon platforms agree with predictions. During disturbed conditions the measured and predicted ion concentrations agree for high ion densities of ∼105 cm−3. The ionic conductivities appear to be approximately independent of the type of measurement platform used. It is suggested that there may be large ions in the lower stratosphere that are broken up in the sampling process with the experimental techniques employed on the rocket and parachute platforms. The large ionic masses inferred from the mobility measurements on the balloon platform suggest that some fragmentation of the ions may have also taken place in the mass spectrometer samplings on the rocket platform. It is suggested that if these discrepancies are to be resolved, more experiments should be conducted on balloons in which measurements of the ionic mobilities, ionic concentrations, and ionic mass are made on the same platform.