EVOLUTION OF THE MORPHOLOGY AND MICROPHYSICS OF CONTRAIL CIRRUS FROM AIRBORNE REMOTE-SENSING

Contrail cirrus were observed by airborne lidar and multispectral infr ared remote sensing. Results of microphysical analysis were obtained f or two cases of persistent contrail cirrus which form in the same area but of differing maturity. The cross section area of the older contra il was 18 times greater than the newer case. In both cases the inferre d number of particles per distance along the flight track dimension of contrails was nearly similar, close to 26 x 10(11)/m. The average liq uid water concentration of the two cases was similar, but the amount o f water per distance along the flight line dimension was much greater for the older contrail, 34 g/cm and 680 g/cm. In both cases the amount of liquid water in the contrail was much greater than the amount gene rated by the aircraft which produced the contrail. These results are c onsistent with a model of contrail evolution where the effect of the j et exhaust is to generate a dense concentration of small ice particles . Mixing then maintains the total number of particles, and particles g row to the extent of the available vapor in the ambient air.