@Article{KozaiMKKBERLSTDHSJSK:2014:SpDeGr,
               author = "Kozai, Masayoshi and Munakata, Kazuoki and Kato, Chihiro and 
                         Kuwabara, Takao and Bieber, John W and Evenson, Paul and 
                         Rockenbach, Marlos and Lago, Alisson Dal and Schuch, Nelson Jorge 
                         and Tokumaru, Munetoshi and Duldig, Marcus L and Humble, John E 
                         and Sabbah, Ismail and Jassar, Hala K Al and Sharma, Madan M and 
                         K{\'o}ta, Jozsef",
          affiliation = "{} and {} and {} and {} and {} and {} and {} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)}",
                title = "The spatial density gradient of galactic cosmic rays and its solar 
                         cycle variation observed with the Global Muon Detector Network",
              journal = "Earth, Planets and Space",
                 year = "2014",
               volume = "66",
               number = "151",
                pages = "1--8",
             keywords = "Diurnal anisotropy, North-south anisotropy, Heliospheric 
                         modulation of galactic cosmic rays, Solar cycle variation of the 
                         cosmic ray density gradient.",
             abstract = "We derive the long-term variation of the three-dimensional (3D) 
                         anisotropy of approximately 60 GV galactic cosmic rays (GCRs) from 
                         the data observed with the Global Muon Detector Network (GMDN) on 
                         an hourly basis and compare it with the variation deduced from a 
                         conventional analysis of the data recorded by a single muon 
                         detector at Nagoya in Japan. The conventional analysis uses a 
                         north-south (NS) component responsive to slightly higher rigidity 
                         (approximately 80 GV) GCRs and an ecliptic component responsive to 
                         the same rigidity as the GMDN. In contrast, the GMDN provides all 
                         components at the same rigidity simultaneously. It is confirmed 
                         that the temporal variations of the 3D anisotropy vectors 
                         including the NS component derived from two analyses are fairly 
                         consistent with each other as far as the yearly mean value is 
                         concerned. We particularly compare the NS anisotropies deduced 
                         from two analyses statistically by analyzing the distributions of 
                         the NS anisotropy on hourly and daily bases. It is found that the 
                         hourly mean NS anisotropy observed by Nagoya shows a larger spread 
                         than the daily mean due to the local time-dependent contribution 
                         from the ecliptic anisotropy. The NS anisotropy derived from the 
                         GMDN, on the other hand, shows similar distribution on both the 
                         daily and hourly bases, indicating that the NS anisotropy is 
                         successfully observed by the GMDN, free from the contribution of 
                         the ecliptic anisotropy. By analyzing the NS anisotropy deduced 
                         from neutron monitor (NM) data responding to lower rigidity 
                         (approximately 17 GV) GCRs, we qualitatively confirm the rigidity 
                         dependence of the NS anisotropy in which the GMDN has an 
                         intermediate rigidity response between NMs and Nagoya. From the 3D 
                         anisotropy vector (corrected for the solar wind convection and the 
                         Compton-Getting effect arising from the Earths orbital motion 
                         around the Sun), we deduce the variation of each modulation 
                         parameter, i.e., the radial and latitudinal density gradients and 
                         the parallel mean free path for the pitch angle scattering of GCRs 
                         in the turbulent interplanetary magnetic field. We show the 
                         derived density gradient and mean free path varying with the solar 
                         activity and magnetic cycles.",
                  doi = "10.1186/s40623-014-0151-5",
                  url = "http://dx.doi.org/10.1186/s40623-014-0151-5",
                 issn = "1343-8832",
                label = "self-archiving-INPE-MCTI-GOV-BR",
             language = "en",
           targetfile = "Kozai_Spatial.pdf",
        urlaccessdate = "25 abr. 2024"
}