Archive for February, 2010

To boldly go with SDO

Posted: February 8, 2010 by Rog Tallbloke in Uncategorized


SDO-NASA Mission

Post updated with launch pics! See below

We don’t usually do “current affairs” here, but this news release from NASA is worthy of a post, for several reasons.

First and foremost, it is an exciting mission, which NASA dubs:The ‘Variable Sun’ Mission”. This is in itself a fresh departure, since NASA has been firmly in the “It can’t be anything else so it must be co2″ camp for years. Someone at mission control must have seen which way the solar wind is blowing, and has realized that what is needed is a “Five year mission to the centre of the solar system, to explore new worldviews, seek out new climate variables…  To Boldly Go where no Mann has gone before”.

Secondly, it  is of genuine interest to those of us who know that the Sun is a lot more variable than some (mentioning no names, Dr S.) have hitherto had people believe. The probe is designed to study the regions of the Sun’s broad range of radiation wavelengths and particle emissions which have the most variability, the extreme ultra-violet and the solar wind.

‘Solar constant’ is an oxymoron, says Judith Lean of the Naval Research Lab. “Satellite data show that the sun’s total irradiance rises and falls with the sunspot cycle by a significant amount.”


So, enough of the hyperbole, what about the hardware?
The SDO’s AIA  ‘Atmospheric Imaging Assembly‘ will image the solar atmosphere in multiple wavelengths to link changes in the surface to interior changes. Data will include images of the Sun in 10 wavelengths every 10 seconds. It will have 1/2 greater image resolution than STEREO  and 3/4 greater imaging resolution than SOHO at a resolution of about 1 arcsec. The image cadience also varies. SDO takes 1 image every  second. At best STEREO takes 1 image every 3 minutes and SOHO takes 1 image every 12 minutes.

The EVE instrument has 70 times better spectral resolution in the Extreme UV than current measurements and has 30 times better time cadence / duty cycle to to understand variations on the timescales which influence Earth’s climate and near-Earth space.

Specific scientific objectives for the HMI instrument are to measure and study:

  1. Convection-zone dynamics and the solar dynamo;
  2. Origin and evolution of sunspots, active regions and complexes of activity;
  3. Sources and drivers of solar magnetic activity and disturbances;
  4. Links between the internal processes and dynamics of the corona and heliosphere;
  5. Precursors of solar disturbances for space-weather forecasts.

The HMI instrument will produce measurements in the form of filtergrams in a set of polarizations and spectral line positions at a regular cadence for the duration of the mission that meet these basic requirements:

  1. Full-disk Doppler velocity and line-of-sight magnetic flux images with 1.5 arc-sec resolution at least every 50 seconds.
  2. Full-disk vector magnetic images of the solar magnetic field with 1.5 arc-sec resolution at least every 10 minutes.

H/t to Oliver Manuel and Gray Stevens

Launch has been delayed again:
The new scheduled launch will be on Wednesday February 10, 2010 at 10:30

Bon Voyage SDO!

Update 11-02-2010

The Launch was a peach. Textbook precision from NASA.  Congrats to all involved.

El Nino and the solar cycle

Posted: February 6, 2010 by Rog Tallbloke in Uncategorized

As you can see from the chart below, El Nino tends to occur away from the peak of the solar cycle. One of the outcomes of this is that the solar cycle’s effect on temperature gets underestimated, because El Nino lifts global temperature at times of low solar activity, and is suppressed at times of high solar activity. La Nina often occurs near the peak of the solar cycle, bringing a couple of cold winters with it. This fact is conveniently disregarded by Dr Leif Svalgaard, who continues to claim the effect of the solar cycle on temperature is only around 0.07C. Rubbish, it’s at least 0.2C, probably more, further amplified by cloud cover change. This means the steady rise in solar activity over most of the C20th was responsible for most of the warming observed, given the over-egging of the global temperature record by Phil Jones at UEA-CRU and James Hansen at NASA-GISS.

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There is an exception to the rule around 1900 but temperatures were low then anyway. My theory, backed up by calculations I have done on steric sea level rise and the gradient of temperature to the thermocline,  is that heat-energy is forced into the ocean as sun spot numbers rise, and is released back out of the ocean on the downslope of the solar cycle and just after minimum. The low run of solar cycles around 1900 allowed the ‘upwelling’ of energy to build up ‘momentum’ and so the heat release continued through the upturn of the low solar cycle. Something similar happened during low solar cycle 20.

The currently high global sea surface temperature is nearly at the same level as 1998, but this is not the whole story. Whereas 1998 was a full blown Pacific Warm Pool event, the current El Nino is a ‘Modoki’ event. This means heat-energy is rising out of the oceans over a broad area of the globe, but the SST’s are not very high in one particular area. This means that much of the heat will escape to space instead of being trapped in by high humidity and then spread around by the trade winds.

This is why temperatures over the continental masses are low, while global lower troposheric temperature is high. Blocking patterns have allowed warm air over the oceans to migrate to the poles, displacing cold air down over the northern hemisphere continents.

The question is, what will happen next? Looking at a similar situation in the past may help. Around 1880, global SST’s peaked in a huge El Nino event, then started to decline, with another big El NINO event 12 years later. Sound familiar? Look how similar the solar cycle phase was then and now.

Sea surface temperature comparison 1880 1985

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I expect we will see a significant downturn in SST over the coming year. My prediction, for what it’s worth, is that global SST will be 0.1-0.15C below Jan 2008 levels by spring 2011.