Trace radioactivity from Japan likely over the Western U.S. today

By: Dr. Jeff Masters , 2:11 PM GMT on March 18, 2011

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Traces of radioactive substances emitted by Japan's damaged Fukushima nuclear power plant will likely arrive over the Western U.S. today, carried by the prevailing west to east winds that have blown over the Pacific Ocean during the past week. Rainfall is expected over California this weekend, and it is likely that the rain will wash radioactive particles out of the air to the surface in quantities that will be detectable at several locations. I want to strongly emphasize that the radioactivity from Japan arriving over the U.S. over the next few days poses absolutely no threat to human health, and is present in only miniscule quantities. The radioactive plumes from Japan have had seven days to dilute over a 5000+ mile journey, and have been subject to deposition to the ocean due to gravity and rainfall along the way. Natural radiation is present in our environment every day, and the extra radiation from the Fukushima nuclear plant will cause much less than a 1% increase this background radiation. Radioactive particles from the Chernobyl disaster in 1986 were detected in North America ten days after that event, and caused no harmful effects. The radiation from Japan over U.S. during the next week should be at levels even lower than the Chernobyl fallout.


Figure 1. Backward trajectories for the air arriving at the surface (red line) and 300 meters altitude (blue line) in San Francisco, California on Saturday, March 19, at 11am PDT. According to the latest run of the GFS model, the air arriving in San Franciso tomorrow will have originated near the surface in northern Japan last Saturday, when radioactive emissions from the Fukushima nuclear plant began. The radioactive particles arriving in California will be in trace quantities, and will have no harmful effects on human health. Images created using NOAA's HYSPLIT trajectory model.

Radioactive plumes emitted from Japan's troubled Fukushima nuclear power plant continue to move offshore to the east over the Pacific Ocean today, thanks to predominantly west winds blowing at 5 - 15 mph. These winds are being driven by the clockwise flow of air around a surface high pressure system centered just southeast of Tokyo. As this high pressure system moves northeastwards, parallel to the Japanese coast, today through Saturday, winds will gradually shift to the southwest, keeping the radiation from the Fukushima plant blowing out to sea. As the winds shift to southwesterly, the sinking air over Japan will be replaced by rising air, and radioactive emissions will begin being lifted high in the atmosphere. Since there is less friction aloft, and the high speed winds of jet stream increase as the air moves higher in the atmosphere, this radiation will undergo long-range transport. Latest trajectory runs using NOAA's HYSPLIT model (Figures 2 - 4) show that radioactivity emitted today could wind up over Alaska after five days, and radioactive particles emitted on Saturday could make it to California by late next week. I've made trajectory plots for the next three days assuming two possible release altitudes--a surface-based release near 10 meters, which should be the predominant altitude in the current situation, and a higher release altitude of 300 meters, which might occur if there is an explosion and major fire. However, the 5-day trek to Hawaii and California is 4000 - 5000 miles, and a tremendous amount of dispersion and dilution of the radioactive plume will occur. Given the current levels of radiation being emitted, any radioactivity reaching Hawaii or the U.S. may be difficult to detect, and will not be a threat to human health. Keep in mind also that the most dangerous radionuclide to human health in the radioactive plume--Iodine-131--has a half life of eight days, so will be reduced by at least 30% after 5 days of travel time.

Of much greater concern is the possibility of dangerous level of radiation over Japan. The next period of onshore winds that will blow radioactivity inland over Japan may occur beginning on Saturday night (U.S. time), continuing through Sunday, according to the latest run of the GFS model. The latest HYSPLIT trajectories show winds on Sunday may carry radiation from the disaster site southwards over Tokyo. A low pressure system is expected to bring considerable rain to Japan on Sunday, and this rain is likely to remove most of the radioactivity from the air where rain and radioactivity are both present. The winds associated with this low are difficult to predict at this time, since the winds will be light and variable.


Figure 2. Five-day forecast movement of plumes of radioactive air emitted at 10 meters altitude (red line) and 300 meters (blue line) at 18 UTC (2pm EDT) Friday, March 18, 2011 from the Fukushima Daiichi nuclear plant. The plumes get caught in a southwesterly flow of air in advance of an approaching low pressure system. The plume emitted near the surface (red line) stays trapped near the surface for 4 days then lifted to 4 km, but the plume emitted at 300 meters is lifted to 5 km altitude after 2 1/2 days by the rising air associated with the approaching low pressure system. Images created using NOAA's HYSPLIT trajectory model.


Figure 3. Five-day forecast movement of plumes of radioactive air emitted at 10 meters altitude (red line) and 300 meters (blue line) at 18 UTC (2pm EDT) Saturday, March 19, 2011 from the Fukushima Daiichi nuclear plant. The plumes get caught in a southwesterly flow of air in advance of an approaching low pressure system and lifted to 4 - 5 km altitude. The plumes are predicted to move over California and Mexico at high altitude. Images created using NOAA's HYSPLIT trajectory model.


Figure 4. One-day forecast movement of plumes of radioactive air emitted at 10 meters altitude (red line) and 100 meters (blue line) at 18 UTC (2pm EDT) Sunday, March 20, 2011 from the Fukushima Daiichi nuclear plant. The plumes get caught northerly winds, and the two lower altitude plumes move over Tokyo by 6 UTC on Monday, March 21. This is a low confidence forecast, as winds are expected to be light and somewhat variable on Sunday over Japan. Images created using NOAA's HYSPLIT trajectory model.

Resources
Seven-day weather forecast for Sendai near the Fukushima nuclear plant

The Austrian Weather Service is running trajectory models for Japan.

Current radar loops from the Japan Meteorological Agency

Jeff Masters

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Quoting pottery:

Three blind mice ?


Leave it to you, pot. LOL
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Post 630, you sure you weren't referring to this blog instead?
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Quoting caneswatch:
"You have paid the price for your lack of vision."


Star Wars V or VI dont remember
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Blazing Saddles, Cat Balou, How The West Was Won, Butch and Sundance......
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Quoting caneswatch:
"You have paid the price for your lack of vision."


Return of the Jedi.
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Things don't look good in Libya. Could be a lot of action there soon. I hope it doesn't get too out of hand. Could be a terrible situation lasting a long time.
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Quoting caneswatch:
"You have paid the price for your lack of vision."

Three blind mice ?
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Oh, wait. It looks like it was something freaky on the last page.

However, I thought the blog changes were supposed to get rid of that effect.... hmmm....

So what's the latest on our tempeste tropical in the Reunion sector?
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"You have paid the price for your lack of vision."
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Quoting NRAamy:
Hello to my favorite non-husband.....


You being Naughty?
On Supermoon Night???
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Ready? OK, when we get outside and we get to the horses, whatever happens, just remember one thing... hey, wait a minute.
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Quoting NRAamy:
It's Burt Reynolds in Smokey and the Bandit!


Never heard of it.
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Hello to my favorite non-husband.....

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It's Burt Reynolds in Smokey and the Bandit!
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Quoting GeoffreyWPB:
"Emily, I have a little confession to make. I really am a horse doctor. But marry me, and I'll never look at any other horse."


A Day at the Races
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Quoting NRAamy:
Come again?

I will leave that alone....
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"Emily, I have a little confession to make. I really am a horse doctor. But marry me, and I'll never look at any other horse."
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Oh my.
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Quoting GeoffreyWPB:
I know it was you, Fredo. You broke my heart. You broke my heart!


Ma tuo padre pensa antico! (American Movie)
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Geez, what's going on with the blog? Everything is out of whack. What's the location of that Developer's Blog again?
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Come again?
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Lordy,..LOL...now I know were in trouble....lol
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Quoting NRAamy:
"You wanna jump somethin', jump me!!"


Not now Amy, we're doing movie lines.
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"You wanna jump somethin', jump me!!"
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Quoting GeoffreyWPB:
I know it was you, Fredo. You broke my heart. You broke my heart!


The Godfather II Mike to his brother, too easy
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Quoting GeoffreyWPB:
Yes...we have no lives. LOL


Speak for yourself.
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I know it was you, Fredo. You broke my heart. You broke my heart!
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Quoting NRAamy:
"And dont call me Shirley!"


NRA...you're always a hoot...on the spot..hoot..lol
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A "don't bug us, we're busy" message from
http://en.wikipedia.org/wiki/2011_Sendai_earthqua ke_and_tsunami
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Please wait a while before you try to access this page again.
* Error reading from pool counter server
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Quoting NRAamy:
"And dont call me Shirley!"


Airplane, too easy. Something remote.
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"And dont call me Shirley!"
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Yea, we're gonna get in trouble any moment now....but heck, I'm too old to go to detention !
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Quoting atmoaggie:
Interesting.

Looking around, neat website posted by Watts showing the data from a Geiger counter in Tokyo.
(Cue the moronic flamers, though I haven't been to WUWT in a month or so)

Here is the site: http://www.denphone.com/denphone-tokyo-office-gei ger-counter
Radiation readings over the last 4 days in Tokyo not changing much.


The weather report just stated that the winds will be changing and moving all of the radiation back over Japan and even South to Tokyo. This will last for at least 5 days before the winds change direction and start blowing East again. They expect all the levels to rise by tomorrow.,
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Quoting EYEStoSEA:


Well shoot...when I'm put on the spot I cant think !!


Clint Eastwood, Dirty Harry LOL
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Yes...we have no lives. LOL
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Quoting aspectre:
Posted at GoComics on March10th, the day before the SendaiEarthquake
Interesting.

Looking around, neat website posted by Watts showing the data from a Geiger counter in Tokyo.
(Cue the moronic flamers, though I haven't been to WUWT in a month or so)

Here is the site: http://www.denphone.com/denphone-tokyo-office-gei ger-counter
Radiation readings over the last 4 days in Tokyo not changing much.
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Quoting Grothar:


You can throw out any old movie or TV line and either GeoffWPB or I will know what it is. Go ahead!!


Well shoot...when I'm put on the spot I cant think !!
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Quoting EYEStoSEA:


Yep...you're real old...lol.....


You can throw out any old movie or TV line and either GeoffWPB or I will know what it is. Go ahead!!
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Quoting GeoffreyWPB:


Did you know "Alfalfa" was in "It's A Wonderful Life"?


No, I didn't, can you believe that?
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Quoting DontAnnoyMe:


I was in love with Darla.


Now DAM , you just watched the remakes...not the originals /;]
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Quoting Grothar:


Why you little Rascal You!


Did you know "Alfalfa" was in "It's A Wonderful Life"?
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Quoting EYEStoSEA:


"Might choke Arti...won't choke Stimey" now will see how old u r....hehe


I was in love with Darla.
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Quoting Grothar:


Why you little Rascal You!


Yep...you're real old...lol.....
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Quoting EYEStoSEA:


"Might choke Arti...won't choke Stimey" now will see how old u r....hehe


Why you little Rascal You!
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Quoting GeoffreyWPB:


I resemble that remark. Only have 144 episodes to catch up on.


What season are you up to?
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Quoting Grothar:


I'm here, I'm here. Just enjoying how some many misinterpret what is written and the snide little remarks that go back and forth. Better than watching Judge Judy.


"Might choke Arti...won't choke Stimey" now will see how old u r....hehe
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Quoting Grothar:


I'm here, I'm here. Just enjoying how some many misinterpret what is written and the snide little remarks that go back and forth. Better than watching Judge Judy.


I resemble that remark. Only have 144 episodes to catch up on.
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Quoting Grothar:


I'm here, I'm here. Just enjoying how some many misinterpret what is written and the snide little remarks that go back and forth. Better than watching Judge Judy.


DAM, I thought that stuff only goes on on Classic WU. lol
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Quoting EYEStoSEA:
Well, I miss Grothar...he needs to get his old self on here...!


I'm here, I'm here. Just enjoying how some many misinterpret what is written and the snide little remarks that go back and forth. Better than watching Judge Judy.
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Well, I miss Grothar...he needs to get his old self on here...! OOPs.....lol
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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