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A NOAA-STAR
dataset is born…
What does a new entrant in the lower troposphere satellite record stakes really imply?
At the beginning of the year, we noted that the NOAA-STAR group had produced a new version (v5.0) of their MSU TMT satellite retrievals which was quite a radical departure from the previous version (4.1). It turns out that v5 has a notable lower trend than v4.1, which had the highest trend among the UAH and RSS retrievals. The paper describing the new version (Zou et al., 2023) came out in March, and with it the availability of not only updated TMT and TLS records (which had existed in the version 4.1), but also a new TLT (Temperature of the Lower Troposphere) record (from 1981 to present). The updated TMT series was featured in the model data comparison already, but we haven’t yet shown the new TLT data in context.
Readers will recall that the TLT product is nominally a weighted average of atmospheric temperature anomalies from the surface up to 5km or so. The weighting varies a little between land and ocean, and as a function of topography or surface type (some model-observation comparisons take this into account, but a global uniform weighting is often good enough).
The nature of the measurement, using off-nadir scans of the instrument made the retrieval more noisy than other MSU prodcuts, and it has taken time to deal with those issues. Some long-timers might even recall the rather tumultuous history, involving over-confident claims of precision, the discovery of systematic biases because of orbital decay, corrections, independent replication and more errors, more corrections, etc.
[ E.G., Spencer & Christy's evangelical 1990 Science Editorial :
"Virtually everyone, children included, is concerned about global climate change and especially about the greenhouse effect. They have learned of increases in carbon dioxide. They have been told repeatedly that temperatures will increase 9'F. Political pressure is mounting to take action regardless of cost, and to take action now.
But how good is the evidence, and how likely is substantial global warming? When might it happen?
Applying the customary standards of scientific inquiry, one must conclude that there has been more hype than solid facts ...
Modeling of global climate is largely concentrated on examining effects of doubling the atmospheric content of greenhouse gases... the answers they get are functions of the models they employ."]
This history should temper any claims now that the structural uncertainty has finally been beaten down, but it’s worth digging in a little deeper to see where it comes in.
