author = "Li, Guozhu and Ning, Baiqi and Abdu, Mangalathayil Ali and Wan, 
                         Weixing and Wang, Chi and Yang, Guotao and Liu, Kangkang and Liu, 
                         Libo and Yan, Chunxiao",
          affiliation = "{Chinese Academy of Sciences} and {Chinese Academy of Sciences} 
                         and {Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Chinese Academy of Sciences} and {Chinese Academy of Sciences} 
                         and {Chinese Academy of Sciences} and {Chinese Academy of 
                         Sciences} and {Chinese Academy of Sciences} and {Chinese Academy 
                         of Sciences}",
                title = "First observation of presunset ionospheric F region bottom-type 
                         scattering layer",
              journal = "Journal of Geophysical Research: Space Physics",
                 year = "2017",
               volume = "122",
               number = "3",
                pages = "3788--3797",
                month = "Mar.",
             abstract = "The bottom-type irregularity scattering layer (BSL) that can 
                         appear in the ionospheric F region bottomside has been observed 
                         generally after sunset, serving as a possible telltale of 
                         equatorial spread F (ESF). Using simultaneous multibeam radar 
                         measurements over two low-latitude stations, Sanya (18.3 degrees 
                         N, 109.6 degrees E; dip latitude 13 degrees N) and Fuke (19.3 
                         degrees N, 109.1 degrees E; dip latitude 14 degrees N) in China, 
                         we report, for the first time, a thin BSL that initially occurred 
                         at presunset (similar to 1720 LT), much earlier than the 
                         occurrence of BSL generated from the equatorial plasma shear 
                         vortex-driven instability. The presunset BSL was situated around 
                         225km altitude and continued to exist until the appearance of ESF 
                         plumes after sunset (similar to 1930 LT). Interestingly, the 
                         Doppler velocities of the presunset BSL echoes measured by the 
                         radar and the F layer virtual heights obtained from the collocated 
                         Digisonde measurements over Sanya both show oscillations with a 
                         period of about 1 h, suggesting a close link between the 
                         occurrences of the BSL and of F region plasma density large-scale 
                         wave structure before sunset. These observations could imply an 
                         important role of gravity waves in the generation of the presunset 
                         F region bottom-type irregularities.",
                  doi = "10.1002/2016JA023647",
                  url = "http://dx.doi.org/10.1002/2016JA023647",
                 issn = "2169-9402",
             language = "en",
           targetfile = "Li_first.pdf",
        urlaccessdate = "24 nov. 2020"