Microphysical modeling of cirrus: 1. Comparison with 1986 FIRE IFO measurements

摘要: We have used a one-dimensional model of cirrus formation to study the development clouds during 1986 First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE) intensive field observations (IFO). The includes microphysical, dynamical, and radiative processes. Sulfate aerosols, solution drops, ice crystals, water vapor are all treated as interactive elements in model. Ice crystal size distributions fully resolved based on calculations homogeneous freezing nucleation, growth by deposition, evaporation, coagulation, vertical transport. focused observed November 1, 1986. Vertical wind speed for simulation is taken from mesoscale appropriate time period. suggested that strong upward motions over Wyoming subsequent horizontal transport upper level moisture were responsible Wisconsin this date. assumed our could be represent column moving period several hours. nucleation occurs 8 10-km region result updrafts (and cooling) early simulation. Growth, sedimentation these crystals broad cloud (5–10 km thick) with an optical depth 1–2 after few hours, agreement FIRE measurements. Comparison aircraft microphysical measurements made indicates generated reasonable content, but predicted number densities too low, especially radii less than about 50 μm. Sensitivity tests suggest better between simulated properties achieved if rate higher or stronger mixing (perhaps associated multidimensional motions) present.