The atmospheric boundary layer (ABL) consists of alive turbulences and convections and so on. However, the measurement of the structure in ABL, particularly upper level of ABL, is generally difficult to observe its structure. Indeed, radar observation is needed for better understanding of the structure of ABL by the analysis of clear-air echoes (CAE). Although several investigations have been conducted, polarimetric radar research for CAE is not yet sufficient. In this study, CAE observed by COBRA (CRL Okinawa Bistatic polarimetric Radar) was analyzed for ABL structure study. COBRA observed a thermal for its structure’s detail with 400 MHz wind profiler (400 MHz WPR). Used equipments are COBRA, 400 MHz WPR, GPS radiosonde soundings, AMeDAS and automatic weather stations. As the results, the height of CAE corresponded to that of large gradient in air refractive index. The height of CAE also has good agreement with observed boundary layer by 400 MHz WPR. The shape of CAE appeared as if doughnut by PPI (Plane Position Indicator) and as if U-reverse shape in RHI (Range Height Indicator). Three-demensional structure and variation of the same thermal was observed with COBRA RHI and 400 MHz WPR. The higher the CAE height is, the larger the scale of the turbulent scale.
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Takahashi Master thesis
