MU radar observations of tropopause variations by using clear air echo characteristics

• Hermawan E.

  Radio Atmospheric Science Center, Kyoto University

• Tsuda T.

  Radio Atmospheric Science Center, Kyoto University

• Adachi T.

  Radio Atmospheric Science Center, Kyoto University

Abstract

We present in this paper the characteristics of clear air echoes revealed by the MU radar experiments in Shigaraki, Japan (34°51′ N, 136°06′ E). In particular, we study a relation between atmospheric stability, represented by Brunt Vaisala frequency squared, N², and both the vertical echo power and the aspect sensitivity. On August 24-25, 1991, echo power was collected by steering the zenith angle of the antenna beam of the MU radar from the zenith to 28°with a step of 2°. Aspect sensitive echoes were detected in the lower stratosphere and some regions in the troposphere. We found that a ratio of vertical echo power to oblique echo power at 10° can represent the magnitude of aspect sensitivity. We compared profiles of both the vertical echo power and the aspect sensitivity with N², inferred from a radiosonde sounding at the radar site. Cross correlation analysis indicates that a rapid increase of both vertical echo power and the aspect sensitivity near the tropopause usually coincides with a step-wise enhancement of N². <BR>We also analyzed four other MU radar observations, continued 4-5 days each, and obtained a statistical results that the mean CCF values between profiles of N² and vertical echo power and the aspect sensitivity are 0.89 and 0.86, respectively. Their mean lag distance was about 71 m and 134 m, with a standard deviation of 77 m and 176 m, respectively. That is, the increase in the vertical echo power and the aspect sensitivity generally occurred slightly higher altitude relative to a sharp increase in N2. However, we also found some exceptional cases when the lag distance was as large as several hundred meters or even negative.

Journal

• Earth, Planets and Space

  Earth, Planets and Space 50 (4), 361-370, 1998

  Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan, The Volcanological Society of Japan , The Geodetic Society of Japan , The Japanese Society for Planetary Sciences

Keywords

• Space and Planetary Science
• Geology

Details

• CRID: 1390001206510458624
• NII Article ID: 10002206476
• NII Article ID: 130003780718
• NII Book ID: AA11211921
• DOI: 10.1186/bf03352122
• ISSN: 18805981
• ISSN: 13438832
• ISSN: http://id.crossref.org/issn/13438832
• Web Site: https://link.springer.com/content/pdf/10.1186/BF03352122.pdf
• Web Site: https://link.springer.com/article/10.1186/BF03352122/fulltext.html
• Web Site: http://link.springer.com/content/pdf/10.1186/BF03352122
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed