Observations of Cloud Convections and Inertio-Gravity Waves

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The objective of this three-year research is to study could convections, inertio-gravity waves and their interactions, based on observations and data collections in Japan, Thailand and Indonesia.In order to obtain high-resolution vertical profiles of wind and temperataure, a transportable GPS rawinsonde system has been installed. Time and spatial variations have been separated by simultaneous rawinsonde-radar observations at radar sites such as Shigaraki. Japan and Serpong and Kototabang Indonesia. Furthermore, operational rawinsonde data in Japan, Thailand and Indonesia have been collected, and objective analysis data by JMA and NOAA haver been used for comparison. All the observational data have been analized climatologically. Wave parameters and convection activities have been obtained quantitatively as functions of season, altitude, (latitude, longitude.) and background meteorological parameters (varied with synoptic-scale disturbances and monsoon circulations).Technologically, we have established the rawinsonde observations as a useful method for inertiogravity waves although the wind fluctuation amplitude is somewhat attenuated. Applying this technique to operational rawinsonde data, we have found that waves induced by orography of eastern Japan produce a maximum of inertio-gravity waves in the lower stratosphere in winter, and day-to-day and interannual variations associated with those of troposphere. Convective cloud activities and inertio-gravity wave activities have been studied and compared with each other also for Baiu season. In tropics, correlations between waves with periods of a few days to about ten days and precipitating convective clouds have been found. Correlations between gravity-wave activity, convective cloud activity and background wind and temperature have been recognized also in a quasi-biennial time-scale both in Japan and tropics.