Analysis of the ozone reduction event over the southern tip of South America in November 2009

Akiyoshi, Hideharu*; Kadowaki, Masanao; Nakamura, Haruna*; Sugita, Takafumi*; Hirooka, Toshihiko*; Harada, Yayoi*; Mizuno, Akira*

Journal of Geophysical Research; Atmospheres, 123(22), p.12523 - 12542, 2018/11

AA2018-0443.pdf:12.61MB

https://doi.org/10.1029/2017JD028096

A reduction of the total ozone over the southern tip of South America lasting 3 weeks occurred in November 2009. Analyses of the ERA-Interim reanalysis data and the total ozone observed by the Ozone Monitoring Instrument indicate that the total ozone reduction event was caused by a migration of the polar vortex toward the South American continent at the time of the vortex breakup. The vortex migration is associated with an enhanced wave flux from the troposphere at 120-150W and 50-60S to the west of the South American continent to the stratosphere over the southern part of the continent, which led to a large negative geopotential height anomaly in the lower stratosphere. In November, a blocking event was diagnosed from the 500-hPa geopotential height over the west of the South American continent. These results suggest a relation between the long-lasting reduction of the total ozone over the southern tip of South America and the blocking phenomenon in the troposphere of the Southern Hemisphere through wave propagation from the blocking region in 2009. Analysis of the total ozone anomaly for 50-60S and 65-75W over the southern tip of South America in November for 1979-2015 indicates that the negative ozone anomaly in November 2009 was one of the largest anomalies in this 37-year period and was associated with the large negative geopotential height anomaly in the lower stratosphere. Analyses of dynamical fields were also conducted for other years with large geopotential height anomalies.

Comparative study of granitic and sedimentary groundwater colloids by flow-field flow fractionation coupled with ICP-MS

Saito, Takumi; Hamamoto, Takafumi*; Mizuno, Takashi; Iwatsuki, Teruki; Tanaka, Satoru*

Journal of Analytical Atomic Spectrometry, 30(6), p.1229 - 1236, 2015/06

https://doi.org/10.1039/C5JA00088B

Size distribution and elemental compositions of colloids in granitic and sedimentary deep groundwater was determined by flow field flow fractionation (Fl-FFF) combined with ICP-MS. In the granitic groundwater organic colloids and various inorganic elements were found in limited size ranges (10 nm and 140 nm). The presence of different types of organic colloids was suggested in this groundwater. Most of the inorganic elements exhibited similar size distributions at 10 nm, which were largely overlapped with organic colloids rich in fluorophores. In the sedimentary groundwater small organic and probably inorganic colloids were found at 5 nm together with relatively large inorganic colloids. Organic colloids in this groundwater were homogeneous in terms of their sizes and the compositions of chromohores and fluorophores. The size distribution of inorganic elements depended on their types, indicating the presence of different host colloidal phases for them.

Measurement of 100 MeV/u carbon incident neutron production cross sections on a carbon target

Shigyo, Nobuhiro*; Uozumi, Yusuke*; Uehara, Haruhiko*; Nishizawa, Tomoya*; Mizuno, Takafumi*; Satoh, Daiki; Sanami, Toshiya*; Koba, Yusuke*; Takada, Masashi*; Matsufuji, Naruhiro*

JAEA-Conf 2013-002, p.137 - 142, 2013/10

https://doi.org/10.11484/jaea-conf-2013-002

Heavy ion cancer therapy has been increased by reason of its clinical advantages. During the treatment, the secondary particles such as neutron and -ray are produced by nuclear reactions of a heavy ion incidence on a nucleus in a patient body. Estimation of double differential cross sections of secondary neutron is important to risk assessment of extra dose to organs in the vicinity of the irradiated tumor. Accurate data in neutron energy around 1 MeV is required because neutron in the energy region has large relative biological effectiveness. Neutron double differential cross sections by inducing 290 MeV/u carbon ion to bio-elements have been obtained experimentally. In order to have knowledge of neutron production by deceleration carbon in a human body, we measured the neutron yields from carbon ion incidence on a carbon target of neutron energy below 1 MeV in wide angular range from 15 to 90 with 100 MeV/u.

High linear power irradiation tests with Am-MOX fuels, 1; Outline of the irradiation test program

Maeda, Seiichiro; Mizuno, Tomoyasu; Aoyama, Takafumi; Kitamura, Ryoichi; Takeuchi, Norihiko; Abe, Tomoyuki

no journal, , 

To confirm thermal performance of FBR-MOX fuels containing minor actinides such as americium, the irradiation experiment was performed with low-density MOX fuels containing americium at a high linear power in the fast experimental reactor "Joyo". The post-irradiation-experiment is successively proceeding at hot cell facilities. An overall plan and an outline of the irradiation program are presented in this report.