@Article{AbduSouzBatiSobr:2003:ReMoBr,
               author = "Abdu, Mangalathayil Ali and Souza, Jonas Rodrigues de and Batista, 
                         Inez Staciarini and Sobral, Jos{\'e} Humberto Andrade",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "Equatorial spread F statistics and empirical representation for 
                         IRI: a regional model for the brazilian longitude sector",
              journal = "Advances in Space Research",
                 year = "2003",
               volume = "31",
               number = "3",
                pages = "703--716",
             keywords = "magnetic declination control, solar cycle variations, 
                         irregularities, scintillations, dynamo.",
             abstract = "The empirical representation of the equatorial spread F (ESF) 
                         statistics in the IRI scheme requires well established 
                         distribution statistics of ESF occurrence and intensity as a 
                         function of local time, season/month, latitude and solar and 
                         magnetic activity levels. We present here a regional model for the 
                         quiet-time spread F distribution in the Brazilian longitude 
                         sector. In view of the well known dependence of spread F 
                         occurrence on magnetic declination angle, and the fact that the 
                         declination angle varies rapidly from the west coast (Peruvian 
                         sector) to the east coast (Brazilian sector) of south America the 
                         present model can be said to be valid for the latter sector. 13 
                         years of spread F data simultaneously collected (during 1978-1990) 
                         over the equatorial site Fortaleza and low latitude site Cachoeira 
                         Paulista are used in this model. Only spread F data that is 
                         believed to be related to plasma bubble developments is used in 
                         the model. The data were first grouped into solar flux range bins 
                         representing low, medium, and high solar activity levels, 
                         represented, respectively, by F10.7 less than or equal to 100; 100 
                         < F10.7 < 180; and F10.7 greater than or equal to 180. Spread F 
                         percentage occurrence as a function of (nocturnal) local time for 
                         each of the 12 months in each solar flux range was calculated, and 
                         form the database for the model. Cubic-B spline fits of the data 
                         in local time, latitude, season/month and solar flux nodes 
                         constitute the structure of the present model. The model confirms 
                         many characteristic features of the spread F statistics already 
                         known as well as brings out some new outstanding features for the 
                         Brazilian sector. Among the results to be highlighted are: The 
                         spread F onset and peak occurrence get delayed in local time with 
                         increasing distance from the equator, indicating the plasma bubble 
                         origin for the low latitude ionogram spread F traces; The plasma 
                         bubble occurrence as well as the vertical rise velocity increase 
                         with the increase in solar flux; They attain larger values in 
                         summer months (centered around December) than in equinoctial 
                         months (March and September). The latitudinal variation in spread 
                         F, though based only on two-station data sets in this study, looks 
                         compatible with the latitude variation of ion density fluctuations 
                         observed by the AE-E satellite. The-model wil be made available to 
                         interested users.",
           copyholder = "SID/SCD",
                  doi = "10.1016/S0273-1177(03)00031-0",
                  url = "http://dx.doi.org/10.1016/S0273-1177(03)00031-0",
                 issn = "0273-1177",
             language = "en",
           targetfile = "1-s2.0-S0273117703000310-main.pdf",
        urlaccessdate = "20 maio 2024"
}