A Validation Method for Flight Cloud Seeding Using Airborne Radar over the Pyeongchang Region

Using airborne vertically pointing millimeter-wave radar, five flight experiments
involving glaciogenic cloud seeding over the Pyeongchang region were conducted. In
two of the experiments, an enhancement of the airborne radar reflectivity
approximately 20 min after silver iodide (AgI) flight seeding, differing from the ideal
structure of radar echo associated with natural stratiform snowfall, was detected near
the surface downstream from the seeding path. The enhanced radar echo after
seeding was verified to be caused by the seeding through an investigation of the
interference of two natural precipitation processes: 1) advection of natural precipitation
into the target region and 2) natural growth of cloud particles due to the orographic
effect, gravity waves, or local convergence. These results suggest that the use of
airborne radar to detect near-surface clouds is a powerful experimental tool, enabling a
more rapid and reliable validation than the typical long-term (requiring at least 5 years)
experimental and statistical analyses based on ground-based observations, especially
for the flight seeding experiments.