A Climatology of Ice Supersaturation Conditions in the Upper Troposphere

Satellite and in-situ aircraft data are used to investigate the distribution and frequency of ice supersaturation conditions in the upper troposphere. Supersaturated conditions are found to occur frequently in the upper tropical troposphere and at high latitudes. Observations may indicate extremely high supersaturations over large areas. These conditions may even be present in polar regions. Extensive cross-validation of humidity sensors and possible errors will be discussed. The dynamic and thermodynamic processes responsible for the observed distribution will also be discussed.