Worst radiation plume from Fukushima was blown over Tokyo on March 14-15 — “This was the main deposition event over Japan for the entire disaster” — Large fractions of cesium fell on land

Published: March 1st, 2012 at 4:15 pm ET


Follow-up to: [intlink id=”wind-blowing-from-fukushima-to-tokyo-when-reactor-no-3-exploded-on-march-14-radiation-cloud-reached-south-of-shizuoka-map” type=”post”]{{empty}}[/intlink]

UPDATED: [intlink id=”really-troubling-1000-microsievert-thyroid-dose-south-of-tokyo-over-ten-hour-period-on-march-14-reported-us-navy-nrc-over-300km-from-fukushima” type=”post”]{{empty}}[/intlink]

Title: Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition
Source: Atmospheric Chemistry and Physics; Atmos. Chem. Phys., 12, 2313–2343, 2012 www.atmos-chem-phys.net/12/2313/2012/ doi:10.5194/acp-12-2313-2012
Authors: A. Stohl1, P. Seibert2, G. Wotawa3, D. Arnold2,4, J. F. Burkhart1, S. Eckhardt1, C. Tapia5, A. Vargas4, and T. J. Yasunari6
1 NILU – Norwegian Institute for Air Research, Kjeller, Norway
2 Institute of Meteorology, University of Natural Resources and Life Sciences, Vienna, Austria
3 Central Institute for Meteorology and Geodynamics, Vienna, Austria
4 Institute of Energy Technologies (INTE), Technical University of Catalonia (UPC), Barcelona, Spain
5 Department of Physics and Nucelar Engineering (FEN),Technical University of Catalonia (UPC), Barcelona, Spain
6 Universities Space Research Association, Goddard Earth Sciences and Technology and Research, Columbia, MD 21044, USA
Date: Received: 8 October 2011 – Published in Atmos. Chem. Phys. Discuss.: 20 October 2011
Revised: 1 February 2012 – Accepted: 23 February 2012 – Published: 1 March 2012
Emphasis Added

[…] We explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs […]

14 March 2011.

On 14 March, a cyclone developed over southern Japan, which was linked to a larger cyclone northeast of Hokkaido. […]

The smaller cyclone over Honshu developed rapidly on 15 March, and the FD-NPP plume got caught in its circulation system. It was transported to the south at 18:00 UTC on 14 March, to the southwest six hours later, and back to the north and finally east from about 06:00 UTC on 15 March. The plume covered large parts of centraleastern Honshu and crossed over Tokyo and other major population centers before it left Japan towards the northeast around 18:00UTC on 15 March. Figure 15 (top panel) shows the 137Cs surface concentrations at 06:00UTC on 15 March when precipitation had just started, and Fig. 15 (bottom panel) shows the total 137Cs deposition and precipitation amount on 15 March. The cyclone produced a few millimeters of rain in areas on Honshu Island engulfed by the FD-NPP plume, which led to 137Cs washout. Precipitation was strongest (6 mm) near FD-NPP, leading to high simulated deposition amounts of up to nearly 1000 kBqm−2 in the vicinity of FD-NPP. Tokyo is located just outside of the area with large deposition. Radar data suggests that the precipitation from the GFS model was spatially too smooth and widespread compared to real precipitation patterns. For instance, there was no rain in Tokyo directly, but it did snow in the mountainous areas surrounding the Kanto plain. Thus, our 137Cs deposition may be spatially too extensive and, on the other hand, cannot capture local maxima. This is to be expected, given the global meteorological input data to our simulations. Our simulation suggests that this was the main deposition event over Japan for the entire duration of the disaster. It was due to an unfortunate combination of three factors: (1) the highest emissions of the entire duration of the accident occurred during 14–15 March, (2) the winds transported these emissions over Japan, and (3) precipitation occurred over eastern Japan. Luckily, it did not rain when – according to our simulation – the highest concentrations were advected over Tokyo and other major Japanese cities, saving these places from much higher 137Cs deposition. The actual severity of this episode is still uncertain, as the sensitivity tests in Sect. 4.2.3 have shown that the emissions on 14–15 March are sensitive to the choice of input data for the inversion. […]

The highest release rates occurred on 14 March, when hydrogen explosions occurred in reactor units 3 and 4 and, presumably, unit 2. We also find unexpectedly high 137Cs emissions from 16–19 March, which suddenly dropped by orders of magnitude when spraying of water on the spent-fuel pool of unit 4 started. Thus, we believe that these high emissions are related to the degraded fuel in the spent-fuel pool of unit 4, and this result would also confirm that the spraying was an effective countermeasure at least in this case. […]

The winds transported the FD-NPP emissions towards the Pacific Ocean most of the time, while Japan was affected only occasionally. While this seemed like a relatively fortunate situation for Japan during the accident event, a different picture emerges from our detailed analysis. Exactly during and following the period of the highest 137Cs emission rates on 14 and 15 March, the FD-NPP plume was advected towards Japan and affected large areas in the east of Honshu Island. The advection towards Japan was triggered by a developing cyclone, which produced precipitation on 15 March, leading to the deposition of large fractions of the airborne 137Cs over Japanese land.

h/t het

Read the report here

Published: March 1st, 2012 at 4:15 pm ET


Related Posts

  1. Asahi: Western Tokyo may have been contaminated when radiation plume fell to ground after Reactor No. 2’s core was exposed, says Japan prof. October 27, 2011
  2. US Gov’t: Widespread contamination throughout northern Japan, including Tokyo — “Entire region would be required to be posted as radiological area” March 23, 2012
  3. UN document: "There would be a hazard around eastern part of Japan" — 60 hours of emissions blowing southwest over Tokyo forecasted last March February 15, 2012
  4. Japan Researchers: Radiation on Tokyo island 3 times higher than before Fukushima disaster September 20, 2012
  5. WSJ: High radioactivity has experts ‘puzzled’ and Tokyo-area residents alarmed — Study says “relatively large doses of tainted materials” were dumped on parts of Tokyo November 16, 2011

25 comments to Worst radiation plume from Fukushima was blown over Tokyo on March 14-15 — “This was the main deposition event over Japan for the entire disaster” — Large fractions of cesium fell on land

  • Kevin Kevin

    I would be interested in Arnies view on this.

    In his Japan press conference he underscored how LUCKY Japan was the winds were blowng west at this time, "it saved them from the worst of the disaster."

    And, as we here on the west coast speculted at the time, our exposure at this time may indeed not have been " miniscule" and " not a health concern."

    Odd that.

  • Misitu

    The risk was always there but it is reassuring (!?) to see that hard science is at last looking at what happened, what could/might have happened.

    I remember looking at the Japanese Met Office wind maps around the time of the explosions and thinking that it was not all quite out to sea, never mind the imminence of the typhoon season.

  • Kevin Kevin

    Todays New Yorker and the Frontline documentary all hit hard on the "luck" of the wind blowing out to sea.

    Odd that this is just now being published as I am sure we could have had some proper analysis closer to the time of the event, which would have tempered this meme of "luck" in wind direction now permeating the entirety of the mainstream narrative.

    • aigeezer aigeezer

      "Luck" and "nuke" are words one shouldn't see in the same sentence, but you're right – it seems to be the meme de la semaine now that all the msm have taken a sudden belated interest in Fukushima.

      Luck was the friend of nuke until….

  • Mack Mack


    "Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2–18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history.

    "There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases."

    From the report admin linked:

    • Mack Mack


      They found more than 100% of emissions of Xenon-133 when they should have only found 100%.

      They speculate that it's because Xenon-133 was released before "active venting" "possibly indicating
      structural damage to reactor components and/or leaks due to overpressure…"

      But I wonder if it's from another reactor in Japan that went critical that has been kept silent.

  • Mack Mack


    "For 137Cs, the inversion results give a total emission of 36.6 (20.1–53.1) PBq, or about 43% of the estimated Chernobyl emission."

    "This indicates that emissions may not have originated only from the damaged reactor cores, but also from the spent-fuel pool of unit 4."

    From the report admin linked:

    • Kevin Kevin

      Odd that again SFP 3 completely ignored.

      • Mack Mack

        They say it went kaboom from a hydrogen explosion.

        As you know, many people believe it was a nuclear explosion.

        • Kevin Kevin


          the point I am making is that the speculation after the explosion is that the high readings and ceasium, may have been from SFP 4 versus sfp three which may have gone up at the time.

          It seems there is a coordinated effort to never mention SFP 3 as the culprit of anything yet this reactor constainment was teh site of the worst explosion and very little attention has been paid to it since. Most Pics show little if any active work there to either cool anything or feed and bleed a cooling system for the pool.

          • James2

            Kevin you do seem to be the most persistent liar I've every encountered.

            I guess that's saying something.

        • lokay5 lokay5

          Yes Mack. Nuclear, not hydrogen explosion.

    • Heart of the Rose Heart of the Rose

      @Mack ..Thank you for the links..awesome..

  • Mack Mack

    This interesting, too, regarding CTBTO data:

    "When using the CTBTO data, we found that these data alone could not provide sufficient constraints on the emissions (see also Sect. 4.1). This is true especially for 137Cs, for which the modeled concentrations far from Japan are highly sensitive to changes in the modeling of wet scavenging and thus the model uncertainties are large."

  • Kevin Kevin

    Date: Received: 8 October 2011 – Published in Atmos. Chem. Phys. Discuss.: 20 October 2011
    Revised: 1 February 2012 – Accepted: 23 February 2012 – Published: 1 March 2012
    Emphasis Added

    This is from above.

    Very interesting course of events.

    wonder what the original version looked like and what was revised?

    Crucial it seems.

  • cnsrndctzn cnsrndctzn

    "Plume gate" cover up, this article attempts to summarize this recent FOIA release and complete lack of MSM coverage. Good to pass on to those who are still in a mushroom state.


  • tjharleycjmp


    above is a video posted by 'connecting dots' that shows quite a bit of smoke/steam? coming from reactor 3 today!

    anyone see this? comments?


  • 1 million clicks per second per square meter
    sounds like geigers going wild.

    "highly sensitive to changes in the modeling of wet scavenging and thus the model uncertainties are large"
    that was meant when comparing Cs to Pu/U emissions. the "wet-factor" for Cs is mujo higher.
    me still thnks they are admitting a little more misleading to direct the attention from the ongoing emissions

    • Alice Alice

      I think all their geiger counters were fried and subsequently gave wild readings.

      It's probably more like 10 to the power of.

  • Anthony Anthony

    I believe Japan is entering a *critical mass* period of accumulation. I think thus the flavor of the press admissions and the blue tap waters showing up.

    They are absolutely eluding to and suddenly openly divulging some pretty severe honest late information about the risk loose on the lam…. I know whatever they say is always lesser than what it really is.

    I think the reality will be a crushing time for them as a people. Careful navigation will begin with honesty if they have any hope of ending up on the other side in one piece. That's why I think a lot of truthful nasties are seeing the light of day lately.

    You cant say blue tap water is nothing to worry about or that it is not there.

    The Jig is up.

  • Laterlukemayb Laterlukemayb

    Well I think that if they care anything about the people of Japan they would give them reliable and as accurate data as possible so they can make an informed decision of what they want to do. I'm sure that many would choose not to leave the affected areas because the power Sentimental value has on people. Especially the women. All the same I feel that the women would opt for the survival of their children over material things they may not want to part from. History shows Japan has had more than their share of tragedy's and are a strong willed resourceful people. They can overcome this if the Government concedes that this disaster is something their personally obtained power cannot contain without transparency.

  • NoNukes NoNukes


    The force of sentimental ties to place played out differently in my experience of the gendered responses to this event. I wanted to get on the next plane and my husband was the one tied to place. When I asked him why, since there are many other beautiful places on earth that might be safer, he said, "I'll die here."

    Seemed crazy to me, have we learned nothing from 20+ years of action movies? Don't stop to even grab your stuff, just GO! We are still in CA, now it is probably too late, but we are planning to leave this summer as of now. I wish that he was like the Fukushima surfers who left with the clothes on their backs, or at least that I had left anyway. My Spanish would be so much better by now!

    Is the focus on the easterly winds in the MSM this week meant to reassure consumers in the United States?

  • With the dumping of radioactive water into the sea, the seawater off shore was brought on shore by mist. fogs and rains, Japan is saturated with radiation, time will tell as reports keep coming forth ! Nothing new, we knew this as it happened because it was on our radar as to the worsting of the radiation in Japan, why is their science so slow ?