How to normalise temperature anomalies

Update 2/7/17: I used the wrong GISS data (land only) in the comparison as pointed out by @cce! Agreement now is reasonably good for all temperature series.

This is my crib sheet for comparing temperature anomalies across ground and satellite data. Temperature anomalies are usually (but not always) defined relative to a baseline 30 year ‘climatology’. This simply means that a 30-year average temperature for each month is calculated at each location. The anomaly is then the difference of the mean temperature from that monthly ‘normal’.  First here is a table showing which baseline each group uses.

Group Baseline
NASA GISS 1951 – 1980
Berkeley (BEST) 1951 – 1980
Hadcrut4.5 1961 – 1990
NOAA 1971 – 2000
UAH 1979 – 2010
RSS 1979 – 1984

This means that you can only compare temperature anomalies once they have all been normalised to the same baseline. In order to do that you must first calculate the 30 year average monthly temperature for the new baseline and then subtract it. These are the normalisation ‘offsets’. The UAH baseline 1979-2010 is the only one where all datasets have overlapping values. These are the offsets you need to plot all series together.

Group Offset for 1979 – 2010 baseline
NASA GISS 0.5421 0.4314
Berkeley (BEST) 0.3635
Hadcrut4.5 0.2907
NOAA 0.1838
H4-ST 0.315
RSS 0.0925

UAH clearly has no offset  and  H4-ST is my own Spherical Triangulation of Hadcrut4.5 stations. The offsets above should be subtracted from all anomaly values in each series. Here is an animation of the results.

Comparison of main temperature series normalised to UAH time period.

 

The agreement across groups.  is good except for GISS. The ‘warming’ observed by GISS is far greater than any other temperature index and renormalisation does not change the slope. It is an outlier.

Shown below is the table of offsets needed to normalise all series to the same baseline as Hadcrut4.5. The satellite offsets have been deduced by simply using the negative of the average Hadcrut4.5 anomaly in each of their respective baseline periods.

Group Offset for 1961 – 1990 baseline
NASA GISS 0.1293 0.101
Berkeley (BEST) 0.0643
NOAA -0.1216
RSS -0.1982
UAH -0.2907

Here is the comparison for all series plotted on the Hadcrut4.5 baseline. GISS does show the largest overall warming trend,  but it is not an outlier.

Temperature anomalies for each series normalised to 1961-1990

You can check my values and derive new ones using this spreadsheet. I also cannot understand why there is not already some agreed IPCC renormalisation. However, I am pretty sure it would be the same as mine.

Note: This post was prompted after a twitter exchange with Victor Venema. 😉

Posted in AGW, IPCC, NASA, NOAA, UK Met Office | Tagged | 18 Comments

Updated monitors of UK Power Generation

3pm 20/06/17

I have updated my monitoring of UK Power production to include Solar Energy. These are calculated by the University of Sheffield on behalf of the National Grid. Solar Energy and embedded wind farms are not metered centrally but appear as a reduction in demand on the Grid. In other words The Grid needs to use less traditional generation if output is high. I also correct the metered wind output  to include also embedded farms. The two icons on the right hand menu at the side of this page point to: 1)live power gauges and 2) a timeline of the last 24 hour power generation (shown below)

Posted in Energy, nuclear, renewables, Science | 4 Comments

Central England Temperatures – Spring Record

The Met Office announced that this Spring saw record temperatures in  Wales and Northern Ireland. England was 2nd warmest behind 2011, while Scotland was  fifth warmest. However it was the Central England Temperature (CET) record which seems to have hit the news media, because it shows the warmest year for those stations that contribute.  Let’s have a look.

Yes, 2017 (10.3C) just scrapes past 1893 and 2011 which tied for the previous record of 10.2C. You can also see that there is a long term warming trend which also shows a steeper rise after about 1980.  What about the other seasons?

Here are the trends for all 4 seasons up to 2016

Monthly averaged temperatures for winter(DJF), Spring (MAM), Summer (JJA) and Autumn (SON)

You do see  similar rises in Winter and Autumn, but strangely no significant change at all in summer. These increases still remain small compared to annual variability, for example 2013 was among the coldest Springs on record.

Is there now clear evidence that 400ppm of CO2 is affecting temperatures in the UK? Lets take a look at the annual data.

Annual CET averages. The Blue curve just shows Moana Loa CO2 data extrapolated back to 1750. It has an arbitrary scale.

I think there  is an effect, but make your own mind up.

What about the Little Ice Age? Between 1607 and 1814, there were a total of seven major frost fairs held on the frozen River Thames. The Thames also froze in 1963 and in 1947 and sea ice formed around some beaches.

View from Windsor in 1963

I still remember 1963 because as a small boy I went sledging every every weekend for nearly 3 months. Hamleys sold out of sledges!

 

Posted in AGW, Climate Change, UK Met Office | Tagged | 26 Comments