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Forbush events

As noted here there is a new paper linking Forbush events with changes in DTR. Simply, during a Forbush event  cosmic rays are modulated ( the flux reaching the earth decreases. The theory goes something like this. If GCRs play a role in cloud formation, then when they decrease you should be able to detect an decrease in cloudiness or conversely an increase in solar radiation reaching the surface.

Here’s another link providing some back ground

And here is a link to a paper on the subject http://www.astrophys-space-sci-trans.net/7/315/2011/astra-7-315-2011.pdf

That paper took a rather indirect approach to the problem looking at  changes to DTR and making two inferences. The first inference of course is that the change in DTR is related to Forbush events. The second inference is that the change in DTR was related to changes in cloud cover.

I’m going to take a more direct approach. The hypothesis is that decreased GCR (coincident with a Forbush event) should lead to a decrease in clouds and hence an increase in solar radiation reaching the surface.

The dataset  I have is collected  is from  the best climate stations in the US:  CRN

The data is solar radiation reaching the surface.  I’ve just started the test code, downloading all the datasets and getting the data into nice formats for plotting an analysis. I’ll give you a taste of it here:  On feb 19th, 2011 there was a Forbush event. Below, see the hourly solar radiation for 1 of 206 stations in the CRN database.

 And below find a sample of 9 stations ( ignore the date– my bad it says jan but its feb ) and an example of 25 charts

So,  while I wait on some bug fixes to be upstreamed for the metadata project, I may play around with the solar data.










Categories: Uncategorized
  1. October 19, 2011 at 1:30 AM

    Steven, those plots look exactly like plots of Lorenz system and other chaotic ODEs results. Chaotic, not random ??

  2. steven mosher
    October 19, 2011 at 2:55 AM

    you betcha !

    basically you are seeing the “shadow” of the clouds.. and if clouds are Chaotic then there “shadow” will most likely be chaotic.

    So you have a periodic signal from the sun which changes in amplitude in a deterministic manner ( orbital mechanics) and a turbulant fluid ( the atmosphere) which contains structures ( clouds) that themselves are chaotic.. so insolation is probably going to preserve or be a mapping of the chaotic cloud structure..

    I think in pictures now.. but you get the idea

  3. November 6, 2011 at 1:05 AM

    Look forward to your results. Calder’s background graph shows about 3 days since Forbush event to the maximum. Elsewhere he notes that Svensmark shows a delay of about 5 days to the maximum impact.

  4. magicjava
    February 29, 2012 at 12:42 PM

    Hi Steven,

    I just wanted to point out that Total Solar Irradiance (TSI) is always going up and down. So the amount of light reaching the Earth isn’t just a measure of cloud cover.

    For monthly time scales, Svensmark compared GCRs to the ICCP cloud data from NASA. For daily data he compared GCRs to the MODIS cloud data from NASA.

    If your goal is to check Svensmark’s work, it’s probably best to stick with comparing GCRs to cloud data, rather than sunlight reaching the Earth.

    For what it’s worth, I’ve checked Svensmark’s claims on monthly time scales vs the ICCP data and the correlation holds throughout the entire span of ICCP data.

    • Steven Mosher
      February 29, 2012 at 12:46 PM

      my plan was to normalize TSI. the effect only lasts days, if at all so monthly cant cut it

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