Cosmically, Heliospherically, and Terrestrially, FYI

Last night I decided to have a look at the Space Weather Prediction Center solar charts to see how the geoplanetary magnetic index (Ap) was doing, and decided since I was too tired, I’d put it off until this morning. In my morning sweep of comment moderation, I saw a graph link from WUWT regular “Vukcevic” which was interesting, especially since we’ve had a recent report on the CERN CLOUD experiment designed to prove/disprove the solar-magneto-modulates-cosmic rays-modulates-terrestrial clouds-changes albedo-makes earth warmer/cooler theory, so what follows is sort of cosmic-heliosphere-terrestrial collection of stuff.

First, the Ap index – surprisingly, after a shot upwards this spring, it is still bouncing along the bottom:

Not encouraging.

And the other solar indices are anemic as well. We should be well into the next cycle, but it seems like the solar magneto is still parked in the garage making this sound, picked up by solar listening posts around the world.

Note the difference between the red line (forecast) and the black line (observations).

The slope of the 10.7cm flux also doesn’t look encouraging.

Here’s the neutron flux plot I spoke of at the beginning, plotting Thule Greenland against the sunspot number:

The more neutrons, the more cosmic rays. Here’s how it works, from the University of Delaware page Listening for Cosmic Rays:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cosmic rays do not get far into the atmosphere before they collide with nitrogen or oxygen molecules in the air. The collision destroys the cosmic ray particle and the air molecule, and then several new particles emerge. Cosmic rays from space are termed “primary,” and any particles created in the atmosphere from collisions are termed “secondary.” A bit of energy is transferred to each new secondary particle. Secondary cosmic rays spread out and continue to hit other particles and air molecules, creating a cascade of particles showering towards the ground. Figure 2 shows how the particles shower to the ground. The number of secondary cosmic rays in the atmosphere increases to a maximum, and then diminishes as the energy fades closer to the ground. Because of atmospheric absorption, low energy particles are plentiful and high energy particles are rare. Scientists studying the neutron monitor data are more interested in the energy of primary cosmic rays, before they are affected by the atmosphere. A typical energy level for a galactic cosmic ray detected by the neutron monitor is 17 billion electron volts. Solar cosmic rays are more concentrated towards lower energies. The ones reaching ground level started out with an average energy of about 3 billion electron volts before meeting the atmosphere.

When a cosmic ray hits the atmosphere it produces secondary particles, for example neutrons. The neutrons pass through the atmosphere, through the building, and penetrate the polyethylene and lead casing. The high energy of the cosmic ray particle is reduced by the polyethylene and lead to about l/40 of an electron volt – about the same energy as a regular air molecule. At this energy level, a boron atom in the counter absorbs the neutron, and splits into a fast helium and a fast lithium ion. These energetic ions strip electrons from neutral atoms in the tube, producing a charge in the tube of gas. The charge is detected by the amplifier as one count. Not all neutron monitors are constructed with the lead casing, as the polyethylene is enough to slow the neutron down. The lead increases the neutron count by producing more neutrons as it is bombarded by cosmic rays. Neutron monitors constructed with lead casing count about one neutron for each primary cosmic ray entering the atmosphere through an area equal to the area of the monitor.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here’s the last six months from Thule’s neutron monitor, from UD:

That downward spike in August looks to be a Forbush decrease event, likely related to this story we carried on WUWT: Earth Braces for Solar Storm Tonite

As expected, as we get a modest ramp up in solar activity this past year, the trend of neutrons is slightly downward as the solar magnetic field gets a bit stronger, deflecting a few more cosmic rays.

Here’s some early suggestions of correlation from Bago and Butler. The graph composite below is Joe D’Aleo’s from ICECAP:

Chistensen in 2007 suggested a relationship between cosmic rays and radiosonde (upper air) temperatures:

A recent paper published in Atmospheric Chemistry and Physics suggests that the relationship has been established.

Figure 1 below shows a correlation, read it with the top and bottom graph combined vertically.

Fig. 1. (A) Short term GCR change (significance indicated by markers) and (B) anomalous cloud cover changes (significance indicated by solid contours) occurring over the composite period. GCR data sourced from multiple neutron monitors, variations normalised against changes experienced over a Schwabe cycle. Cloud changes are a tropospheric (30–1000 mb) average from the ISCCP D1 IR cloud values. 

As the authors write in the abstract:

These results provide perhaps the most compelling evidence presented thus far of a GCR-climate relationship.

Dr. Roy Spencer has mentioned that it doesn’t take much in the way of cloud cover changes to add up to the “global warming signal” that has been observed. He writes in The Great Global Warming Blunder:

The most obvious way for warming to be caused naturally is for small, natural fluctuations in the circulation patterns of the atmosphere and ocean to result in a 1% or 2% decrease in global cloud cover. Clouds are the Earth’s sunshade, and if cloud cover changes for any reason, you have global warming — or global cooling.

Well, it seems that Laken, Kniveton, and Frogley have found just such a small effect. Here’s the abstract and select passages from the paper, along with a link to the full paper:

Atmos. Chem. Phys., 10, 10941-10948, 2010

doi:10.5194/acp-10-10941-2010

Cosmic rays linked to rapid mid-latitude cloud changes

B. A. Laken , D. R. Kniveton, and M. R. Frogley

Abstract. The effect of the Galactic Cosmic Ray (GCR) flux on Earth’s climate is highly uncertain. Using a novel sampling approach based around observing periods of significant cloud changes, a statistically robust relationship is identified between short-term GCR flux changes and the most rapid mid-latitude (60°–30° N/S) cloud decreases operating over daily timescales; this signal is verified in surface level air temperature (SLAT) reanalysis data. A General Circulation Model (GCM) experiment is used to test the causal relationship of the observed cloud changes to the detected SLAT anomalies. Results indicate that the anomalous cloud changes were responsible for producing the observed SLAT changes, implying that if there is a causal relationship between significant decreases in the rate of GCR flux (~0.79 GU, where GU denotes a change of 1% of the 11-year solar cycle amplitude in four days) and decreases in cloud cover (~1.9 CU, where CU denotes a change of 1% cloud cover in four days), an increase in SLAT (~0.05 KU, where KU denotes a temperature change of 1 K in four days) can be expected. The influence of GCRs is clearly distinguishable from changes in solar irradiance and the interplanetary magnetic field. However, the results of the GCM experiment are found to be somewhat limited by the ability of the model to successfully reproduce observed cloud cover. These results provide perhaps the most compelling evidence presented thus far of a GCR-climate relationship. From this analysis we conclude that a GCR-climate relationship is governed by both short-term GCR changes and internal atmospheric precursor conditions.

I found this portion interesting related to the figure above:

The composite sample shows a positive correlation between statistically significant cloud changes and variations in the short-term GCR flux (Fig. 1): increases in the GCR flux

occur around day −5 of the composite, and correspond to significant localised mid-latitude increases in cloud change. After this time, the GCR flux undergoes a statistically significant decrease (1.2 GU) centred on the key date of the composite; these changes correspond to widespread statistically significant decreases in cloud change (3.5 CU, 1.9 CU globallyaveraged) over mid-latitude regions.

and this…

The strong and statistically robust connection identified here between the most rapid cloud decreases over mid-latitude regions and short-term changes in the GCR flux is clearly distinguishable from the effects of solar irradiance and IMF variations. The observed anomalous changes show a strong latitudinal symmetry around the equator; alone, this pattern

gives a good indication of an external forcing agent, as

there is no known mode of internal climate variability at the

timescale of analysis, which could account for this distinctive

response. It is also important to note that these anomalous

changes are detected over regions where the quality of

satellite-based cloud retrievals is relatively robust; results of

past studies concerned with high-latitude anomalous cloud

changes have been subject to scrutiny due to a low confidence

in polar cloud retrievals (Laken and Kniveton, 2010;

Todd and Kniveton, 2001) but the same limitations do not

apply here.

Although mid-latitude cloud detections are more robust

than those over high latitudes, Sun and Bradley (2002) identified

a distinctive pattern of high significance between GCRs

and the ISCCP dataset over the Atlantic Ocean that corresponded

to the METEOSAT footprint. This bias does not

appear to influence the results presented in this work: Fig. 6 shows the rates of anomalous IR-detected cloud change occurring over Atlantic, Pacific and land regions of the midlatitudes during the composite period, and a comparable pattern of cloud change is observed over all regions, indicating no significant bias is present.

Conclusions

This work has demonstrated the presence of a small but statistically significant influence of GCRs on Earth’s atmosphere over mid-latitude regions. This effect is present in

both ISCCP satellite data and NCEP/NCAR reanalysis data for at least the last 20 years suggesting that small fluctuations in solar activity may be linked to changes in the Earth’s atmosphere via a relationship between the GCR flux and cloud cover; such a connection may amplify small changes in solar activity. In addition, a GCR – cloud relationship may also act in conjunction with other likely solar – terrestrial relationships concerning variations in solar UV (Haigh, 1996) and total solar irradiance (Meehl et al., 2009). The climatic forcings resulting from such solar – terrestrial links may have had a significant impact on climate prior to the onset of anthropogenic warming, accounting for the presence of solar cycle relationships detectable in palaeoclimatic records (e.g.,Bond et al., 2001; Neff et al., 2001; Mauas et al., 2008).

Further detailed investigation is required to better understand GCR – atmosphere relationships. Specifically, the use of both ground-based and satellite-based cloud/atmospheric monitoring over high-resolution timescales for extended periods of time is required. In addition, information regarding potentially important microphysical properties such as aerosols, cloud droplet size, and atmospheric electricity must also be considered. Through such monitoring efforts, in addition to both computational modelling (such as that of Zhou and Tinsley, 2010) and experimental efforts (such as that of Duplissy et al., 2010) we may hope to better understand the effects described here.

It seems they have found the signal. This is a compelling finding because it now opens a pathway and roadmap on where and how to look. Expect more to come.

The full paper is here: Final Revised Paper (PDF, 2.2 MB)

We all await the result of the CLOUD experiment from Jasper Kirkby. Hopefully it will define this cosmic ray issue with more clarity.