{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:41:36Z","timestamp":1760125296231,"version":"build-2065373602"},"reference-count":67,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,3,27]],"date-time":"2023-03-27T00:00:00Z","timestamp":1679875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42205145","31727901"],"award-info":[{"award-number":["42205145","31727901"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>It is commonly believed that clear-air echoes detected by weather radars are caused by atmobios migration. However, clear-air echoes are sometimes inconsistently related to the activity of living creatures. In some cases, the characteristics of radar products seem to conform to biological scattering, but the movement of echoes cannot be observed. For these reasons, we sought to expand the cause of clear-air echoes from a Chinese Doppler S-band Weather Radar (CINRAD\/SA) in Beijing. Some contradictions were discovered in a case which diverged from previous conclusions. It was found that the progression and movement of clear-air echoes do not conform to the rules of biological activities. The frequency distribution of dual-wavelength ratio peaks is 21.5 dB, which is in accordance with Villars\u2013Weisskopf\u2019s turbulence theory. From 1 May to 20 May, the 58% dual-wavelength ratio between the S-band and the X-band was distributed between 18 dB and 24 dB. These results show that more than half of the clear-air echoes of CINRAD\/SA at night were caused by turbulence in Beijing. A new model of troposcatter propagation, the reflecting-layers model, was then introduced to explain the radar observations. According to the reflecting-layers model, the echoes\u2019 diurnal variation and reflectivity characteristics are attributed to the effects of turbulent mixing. Excessive turbulent mixing affects the generation of the reflective layer, thereby weakening the echo signal. It is necessary to re-examine the position of turbulence in clear-air echoes.<\/jats:p>","DOI":"10.3390\/rs15071781","type":"journal-article","created":{"date-parts":[[2023,3,27]],"date-time":"2023-03-27T04:05:40Z","timestamp":1679889940000},"page":"1781","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Turbulence: A Significant Role in Clear-Air Echoes of CINRAD\/SA at Night"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2956-2165","authenticated-orcid":false,"given":"Yupeng","family":"Teng","sequence":"first","affiliation":[{"name":"Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China"}]},{"given":"Tianyan","family":"Li","sequence":"additional","affiliation":[{"name":"Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Shuqing","family":"Ma","sequence":"additional","affiliation":[{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100089, China"}]},{"given":"Hongbin","family":"Chen","sequence":"additional","affiliation":[{"name":"Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1115","DOI":"10.1126\/science.aat7526","article-title":"A continental system for forecasting bird migration","volume":"361","author":"Horton","year":"2018","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s001140050338","article-title":"The study of bird migration by radar part 1: The technical basis","volume":"84","author":"Bruderer","year":"1997","journal-title":"Naturwissenschaften"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1184","DOI":"10.1175\/1520-0426(1994)011<1184:BLCARE>2.0.CO;2","article-title":"Boundary Layer Clear-Air Radar Echoes: Origin of Echoes and Accuracy of Derived Winds","volume":"11","author":"Wilson","year":"1994","journal-title":"J. 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