In this post I set both UAH and GISS global temperature anomaly series to a common baseline period (1981-2010) and compare them. Even though the UAH series is satellite based and GISS series is station based, the series exhibit striking similarities.
In this previous post, I showed how to convert temperature anomaly time series from one baseline period to another period. I use this technique in this post to directly compare UAH (baseline 1981-2010) and GISS (baseline 1951-1980) series.
The offsets are as follows:
- UAH: -0.000978
- GISS: 0.34958
Since the UAH TLT 5.4 series is based on a 1981-2010 baseline, the offset is nearly zero (-0.00098 versus 0.0).
Users can reproduce my analysis on their own by downloading my CTS.csv file and applying the offsets to the UAH and GISS series.
Comparison of 1981-2010 Baseline Series
Here is a plot of UAH and GISS 12 month moving averages for 1979 to current: Click to EnlargeBoth 12-month moving average series show similar cyclical patterns with positive trends. The UAH series shows a wider swing than GISS in both high and low periods.
Here is the monthly trend chart for the 2 series: Click to Enlarge
We can examine the delta (delta = UAH – GISS) between the two series to see the actual differences between the series each month. Click to Enlarge. In the 1979 – 2011 period, UAH has been greater than GISS 50% of the time and less than GISS 50% of the time.
Once we set UAH and GISS series on the same baseline, the similarities between the 2 series become clear:
- Both series exhibit strong cyclical patterns, attributable in part to El Nino – La Nina cycles
- Both show upward trend
- Timing of cycles is comparable
- UAH is greater than GISS 50% of months
- GISS is greater than UAH 50% of months
- UAH seems to react more to El Nino – La Nina events than GISS