Reduction in Variance - It's the Current Trend

Just for grins, I was playing with the Plain Vanilla UAH data.  Plain Vanilla is just the average of the lower and middle troposphere products.  Since there is a little issue over whether RSS or UAH has the better product due to some middle troposphere divergence, I averaged the two and hope that reduces any bias that UAH or RSS may have.  It comes close, but RSS is still cooler than UAH for the past few years.

Since I have stated that the variance of the data sets is decreasing but noise makes it hard to prove, the chart above is the plot of all Plain Vanilla UAH regions land and ocean , 131 month standard deviations of the detrended data sets.  The chart is busy but neat looking.  You can see not only that the standard deviation is lower at the end, reduction in variance, but where the majority of the reduction is happening.  The dip plateau feature of the tropical data sets is pretty unusual looking.

The top light blue curve is the Northern Polar oceans.  After this years sea ice melt, the change in that data set will be interesting.