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| Titel |
Hindcast of 137Cs in the North Pacific Ocean from 1945 to 2013 by eddy-resolving ROMS |
| VerfasserIn |
Takaki Tsubono, Kazuhiro Misumi, Daisuke Tsumune, Michio Aoyama, Katsumi Hirose |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094267
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| Publikation (Nr.) |
 EGU/EGU2014-9670.pdf |
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| Zusammenfassung |
| We conducted the hindcast of 137Cs activity in the North Pacific Ocean from 1945 to 2013,
before and after the Fukushima Dai-ichi Nuclear Power Plant (1F NPP) accident. We used
the Regional Ocean Model System (ROMS) with high resolution (1/12°-1/4° in
horizontal, 45 levels in vertical), of which domain was the North Pacific Ocean. This
model employed the CORE normal year forcing data for a driving forcing and the
50 years averaged SODA data for boundary conditions. The reconstructed global
fallout due to atmospheric nuclear weapons’ tests and Chernobyl accident was
employed for atmospheric input flux of 137Cs from 1945 to 2013. After the accident, the
atmospheric deposition and direct release of 137Cs from 1F NPP were also employed
for input condition. Five ensemble calculations of 137Cs activity were conducted
by moving the start period of the input flux for one year. The simulated vertical
distributions of 137Cs activity along 165°E represented the overall patterns of the
observed 137Cs activity before (in 2002) and after (in 2012) the accident, in particular
the high activity core of the 137Cs around North Pacific Subtropical Mode Water
and Central Mode Water, indicating that this model can represent the subduction
process and formation of the Mode Waters. The simulated 137Cs activity in the
surface ranged from 0.75 to 2.Bq m-3 in the north of Kuroshio Extension in 2011
before the accident. The main body of high 137Cs activity water from 1F NPP was
transported in the northern part of Kuroshio Extension after the accident. In Sep. 2012, 18
months after the accident, the main body of high 137Cs activity water (≥ 10 Bq
m-3) was located at around 40°N, 150°E-160°W. The water over 10 Bq m-3 of
137Cs activity was not detected in surface layer, but in the layer of Ïăθ=25.8-26.2 at
two small areas (44°N, 180°W-165°W and 48°N, 160°W-140°W). This model
simulation suggests that the main body of high 137Cs activity water from 1F NPP
has never reached the coast of the North American Continent after the accident. |
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