Comments on New RSS v4 Pause-Busting Global Temperature Dataset

earthDr. Roy Spencer explains at his blog the new Carl Mears paper (here we go again) that says the satellites do show warming:

Now that John Christy and I have had a little more time to digest the new paper by Carl Mears and Frank Wentz (“Sensitivity of satellite derived tropospheric temperature trends to the diurnal cycle adjustment”, paywalled here), our conclusion has remained mostly the same as originally stated in Anthony Watts’ post.

While the title of their article implies that their new diurnal drift adjustment to the satellite data has caused the large increase in the global warming trend, it is actually their inclusion of what the evidence will suggest is a spurious warming (calibration drift) in the NOAA-14 MSU instrument that leads to most (maybe 2/3) of the change. I will provide more details of why we believe that satellite is to blame, below.

Also, we provide new radiosonde validation results, supporting the UAH v6 data over the new RSS v4 data.

MT Comparison: RSS v4 versus UAH v6

While Carl and Frank have yet to provide a new analysis of the most popular Lower Troposphere (LT) temperature product, their new analysis for the Mid-Troposphere (MT) has greatly increased their reported warming trend, which used to be very close to ours:

original

If we plot the difference between the two curves, we see more clearly where the discrepancies between the two datasets arise:

RSSv4-vs-UAH-MT

Here I have included their Fig. 7 as an inset to show that they know there is a substantial trend difference between the old NOAA-14 MSU and the newer NOAA-15 AMSU measurements. That trend difference amounts to +0.20 C/decade…a large discrepancy.

Importantly, Mears and Wentz choose to leave this calibration drift in without adjustment for it. In effect they are saying, ‘we don’t know which of the two satellites is at fault, so we will leave both satellites in without adjustment’.

Read rest…

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