Characteristics of inertio-gravity waves revealed in rawinsonde data observed in Korea during 20 August to 5 September 2002

Characteristics of inertio-gravity waves (IGWs) observed at six operational rawinsonde stations in Korea from 20 August to 5 September 2002 and their relationship with convective sources are investigated. Several types of convective systems, including mesoscale convective complexes and Typhoon Rusa, passed the Korean peninsula during the observing period. To categorize the observed waves with and without convective sources, wet and dry periods are defined at each observing site using hourly precipitation and satellite data. Although waves with extremely large values of intrinsic frequency and vertical wavelength are observed mostly in wet periods, the mean values of wave parameters for wet and dry periods are similar. Low-frequency IGWs can originate far from and long before the observing sites, implying that it is unreasonable to correlate convective sources and observed waves at the same location and time. For better correlation of the observed waves and their sources, a three-dimensional ray-tracing model is used. A new wet case is defined on the basis of the occurrence of convection when and where a ray locates in mid-to-upper troposphere. Characteristics of the observed waves for new wet and dry cases differ significantly: the intrinsic frequency is larger but the horizontal wavelength is much smaller for wet than dry cases. Sources for wet cases are mostly convective clouds located northeast and southeast of the observing sites below 5 km. This is clearly distinguished from dry cases, where sources are located mostly in the northwest above 15 km and southeast far from the observing sites below 5 km.