@Article{EcherTsurGonz:2012:ExLoGe,
               author = "Echer, Ezequiel and Tsurutani, Bruce T and Gonzalez, Walter D",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and Jet 
                         Propulsion Laboratory(JPL), California Institute of Technology 
                         (CALTECH) Pasadena, CA, USA and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "Extremely low geomagnetic activity during the recent deep solar 
                         cycle minimum",
              journal = "Proceedings of the International Astronomical Union",
                 year = "2012",
               volume = "7",
               number = "286",
                pages = "200--209",
                month = "July",
             keywords = "Sun: activity, Sun: magnetic \fi,,,,,elds, solar-terrestrial 
                         relations, solar wind.",
             abstract = "Abstract. The recent solar minimum (2008-2009) was extreme in 
                         several aspects: the sunspot number, R z , interplanetary magnetic 
                         \field (IMF) magnitude B o and solar wind speed V were the 
                         lowest during the space era. Furthermore, the variance of the IMF 
                         southward B component was low. As a consequence of these 
                         exceedingly low solar wind parameters, there was a minimum in the 
                         energy transfer from solar wind to the magnetosphere, and the 
                         geomagnetic activity ap index reached extremely low levels. The 
                         minimum in geomagnetic activity was delayed in relation to sunspot 
                         cycle minimum. We compare the solar wind and geomagnetic activity 
                         observed in this recent minimum with previous solar cycle values 
                         during the space era (1964-2010). Moreover, the geomagnetic 
                         activity conditions during the current minimum are compared with 
                         long term variability during the period of available geomagnetic 
                         observations. The extremely low geomagnetic activity observed in 
                         this solar minimum was previously recorded only at the end of XIX 
                         century and at the beginning of the XX century, and this might be 
                         related to the Gleissberg (80-100 years) solar cycle.",
                  doi = "10.1017/S174392131200484X",
                  url = "http://dx.doi.org/10.1017/S174392131200484X",
                 issn = "1743-9213 and 1743-9221",
             language = "en",
        urlaccessdate = "13 maio 2024"
}