A study on the middle and upper atmosphere dynamics

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Based upon our scientific accomplishments the Middle Atmosphere Program (MAP;1982-85), a comprehensive study of the middle and upper atmosphere dynamics has been performed theoretically, observationally and from data analyses for the three fiscal year period of 1986-88. Five related subjects are investigated separately, and their synthesis is pursued through more than 20 scientific meetings which we either hosted ot co-sponsored. Some of them are: the Fourth (International) MST Radar Workshop held in November 29 - December 2,1988 in Kyoto; the First, Second, and Third Middle Atmosphere Symposia held in Tokyo; the STE Symposia of 1986, 87 and 88 held in either Kyoto to tTkyo; the Equatorial Radar Meetings held in Kyoto; and so forth. The principal scientific results obtained are as follows: [1] A universal vertical wavenumber spectrum of the horizontal wind variations is observationally confirmed from MU radar results so that one can conclude that the gravity waves generated in the lowe … More r atmosphere increase their amplitude and become saturated everywhere while propagating upwards, resulting in the momentum fiux deposit and turbulence excitation in the middle atmosphere. [2] The midlatitude ionosphere in the Asian sector is probed for the first time by the MU radar. The mean and seasonal variations of electron density, electron/ion temperature, and ion drift velocity are analyzed. Also a medium-scale gravity wave generated by a large substorm is detected by the MU radar. Midlatitude ionospheric field aligned irregularities (FAI) are detected and their dynamical features are analyzed. [3] Middle atmosphere temperature profiles are remotely sensed by lidar and RASS techniques. The lidar technique makes continuous measurements of the temperature in the 30-70 km height range feasible, while the RASS technique can measure it below 20 km. [4] Based upon the results as shown in the subjects 1-3 above, the gravity wave effects upon the middle atmosphere dynamics are quantitatively investigated, and the dynamical coupling effects caused by upward propagating gravity waves are estimated to construct a new atmospheric model of the middle and upper atmosphere. [5] System analyses of a new equatorial radar are made, and it is found that the construction of a large MST redar system is feasible with our current technical capabilities. Less