@Article{JayanthiPeMaStDAVi:1997:BaObX,
               author = "Jayanthi, Uadya Bhaskaram and Pereira, M. G. and Martin, I. M. and 
                         Stozkov, Y. and D'Amico, Fl{\'a}vio and Villela Neto, Thyrso",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Universidade Estadual 
                         de Campinas (UNICAMP)} and {Russian Academy of Sciences} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)}",
                title = "Electron precipitation associated with geomagnetic activity: 
                         Balloon observation of X ray flux in South Atlantic anomaly",
              journal = "Journal of Geophysical Research",
                 year = "1997",
               volume = "102",
               number = "A11",
                pages = "24069--24073",
                month = "Nov.",
             abstract = "A stratospheric balloon experiment was conducted on December 20, 
                         1994, with an X ray detector to measure fluxes of precipitation 
                         electrons in the South Atlantic anomaly (SAA) region of Brazil. 
                         For the first time in the SAA, this detector systemo f high 
                         sensitivitym onitoredt hree eventso f increasesin X ray fluxes 
                         which are associatedw ith simultaneousd ecreasesin geomagneticH 
                         field component.T he most prominente ventw ith an Xray emissione 
                         quivalent o 1/4 of the disuse cosmic X ray flux permitted the 
                         determination of the spectrum in the energy range of 18.6 to 120 
                         keV. The inferred electron spectrum showed a steep low-energyc 
                         omponenbt elow1 50k eV (E0=16 keV). The electronfl ux estimatesa 
                         re lower compared to earlier balloon results obtained at the time 
                         of a severe magnetic storm. The inferred fluxes from our balloon 
                         experiment are consistent with the electron fluxes observed by the 
                         S3-2 satellite and are lower than the OGO 5 satellite 
                         measurementsb, oth obtained in the SAA at oe-1.3. Further, the 
                         estimatesa re compatible with the P78-1 satellite fluxes present 
                         in the drift loss cone at oe--1.9.5. The presence of sucient 
                         electron fluxes at oe-1.3 region in the SAA, and the similarity 
                         betweent he electrons pectrumo bservedb y the satellitee 
                         xperimentsa nd that inferredi n our balloone xperiment,p romptedu 
                         s to investigateth e possibilityo f the accesso f thesee lectronsp 
                         resenta t satellitea ltitudesi nto oe- 1.13r egionsd uring a mild 
                         storm. Interestingly, this prominent X ray flux event is 
                         associatedw ith two succesives outhwardt urningso f B,. componento 
                         f the interplanetarym agneticf ield (IMF). Precipitationo f 
                         essentialllyo w-energye lectronsb elow1 50k eV occurreda t the 
                         first northward reversal of IMF B,. and after the latter northward 
                         reversal hiher energye lectrons(> 150k eV) alsop recipitatedW. e 
                         suggestth e diffusiono f particles from higher oe regionsi nto 
                         flux tubes connectedto the SAA region,d ue to electric field 
                         fluctuations associatedw ith successiono f substorms,i n a 
                         processs imilar to the {"}enhancedra dil diffusion{"}p roposedb y 
                         Lyonsa nd Schulz[ 1989].T o compare or to relate the inferred 
                         fluxes from the balloon experiment with the satellite 
                         measurementsa nd for a better understandingo f the precipitation 
                         of electrons during magnetic disturbances,i t is necessaryt o have 
                         additional experimental investigations in the SAA.",
             language = "en",
           targetfile = "89 - Electron precipitation associated with geomagnetic.pdf",
        urlaccessdate = "16 jun. 2024"
}