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Why Satellite Records Cannot Be Ignored

January 17, 2015

By Paul Homewood 

 

As we all know by now, satellite data has failed to support claims made by the surface datasets of “hottest year evah”. This has led to many now claiming that the satellite datasets should be ignored, as they don’t measure the same thing.

 

This argument, however, ignores the fact that between 1979 and 2012, the satellite and surface data followed each other closely, albeit not always on a month by month basis. The Woodfortrees graph below compares RSS with GISS between those two years.

There is a slight divergence, with GISS showing a slightly higher trend, but it is relatively small, and the direction of travel is the same.

 

2012

http://www.woodfortrees.org/plot/gistemp/from:1979/to:2012/plot/rss/from:1979/to:2012/plot/gistemp/from:1979/to:2012/trend/plot/rss/from:1979/to:2012/trend

 

But now contrast this with the last two years.

 

 

2014

http://www.woodfortrees.org/plot/gistemp/from:2013/plot/rss/from:2013/plot/gistemp/from:2013/trend/plot/rss/from:2013/trend/plot/uah/from:2013/plot/uah/from:2013/trend

 

Both satellite sets, UAH and RSS are essentially flat, yet GISS has shot up by nearly 0.2C.

 

This divergence appears to be even more inexplicable, because, in his 1987 paper “Global Trends of Measured Surface Air Temperature” James Hansen attempted to verify his surface datasets with atmospheric temperature trends, as measured by radiosondes.

 

image

image

http://pubs.giss.nasa.gov/docs/1987/1987_Hansen_Lebedeff_1.pdf

 

NOTE – “These results suggest that most of the difference between the two temperature records is due to the incomplete spatial coverage of stations”.  

The implication is that the surface and atmospheric temperature changes should correlate over a period of time. Of course, satellite coverage is now nearly universal, with the exception of a small area around the poles, so in this respect satellite data can be regarded as more accurate than radiosondes. 

 

Until the difference between satellite and surface datasets can be fully explained, it is no more than political rhetoric to claim that 2014 was the warmest year on record. 

It is time that NOAA, NASA and the rest took the satellite records seriously, instead of just sweeping them under the carpet.

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4 Comments
  1. January 17, 2015 5:12 pm

    Thanks, Paul.
    Every scientist knows that ignoring data, specially data that is so difficult to obtain as the REMSS and UAH global temperature data sets, is not good science, it is bad science practice.

  2. John F. Hultquist permalink
    January 17, 2015 6:21 pm

    The graph represents 2 things we already know.

    ~ The simple thing is that UAH and RSS are trying to document the same thing using slightly different raw data and making informed, if not exactly correct and similar, adjustments. The UAH team expects to get closer to RSS with a new release. Take the difference between UAH & RSS over the temperature in Kelvin near the surface, about 286 K, and you can see how small this really is.

    ~ The more complex issue to trying to understand what “gistemp” is measuring. Insofar as there is plenty written about this, I’ve just a single thought for here. Where ground is dry heating is more rapid than where moisture is at the surface because evaporation carries the energy away as latent heat. Your post of 2 days ago regarding San Diego’s airport is instructive. What was a bay-side natural environment is mostly covered with concrete and water is routed off buildings, streets, parking lots, and all urban surfaces. Every city does this and where there is still too much water they send it to underground storage (some reused, some released after a delay). An example here:
    http://www.waterworld.com/articles/uwm/articles/print/volume-4/issue-1/features/pond-on-a-pond-.html

    The urban-heat-island (UHI) effect has been documented and adjustments are made. However, those studies were carried out before these water retention schemes were applied on a city scale.

    Now a corollary: In rural areas, irrigation by spraying
    http://en.wikipedia.org/wiki/Center_pivot_irrigation
    increases the humidity of air that tends to keep nighttime temperature higher over much larger areas. Originally the now irrigated lands were not places from which temperatures were measured. The now humid air masses they generate do pass over to sites that do get measured – down wind.
    Because the temperature differences being used (tenths and hundredths of a degree) are so small, water induced physics (WIP – Can I copywrite this?) ought not to be excluded from the discussion.

  3. catweazle666 permalink
    January 17, 2015 9:07 pm

    “Until the difference between satellite and surface datasets can be fully explained…”

    No, no, no, you’ve got it all wrong!

    It just needs Gavin and Zeke to homogenise the satellite data and it will agree with the surface data perfectly.

  4. January 17, 2015 10:40 pm

    Amen!! Well-said. Do you know that many people, incl. many AGWer and respected scientists, dont even know the satelite records exist!? Thats how well NASA and NOAA have shoveled them under the carpet. When you ask those “unknowners” why the National SPACE Agency does not use satelites but land-based thermometers it opens most people’s eyes that something fishy is going on.

    I attended a recent meeting where a former Space Shuttle astronaut spoke and also he said that land-based measurements (in this case not related to GW) need to be compared with satelite to see if there are discrepancies and if so we can learn why and improve our measurements.

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