USHCN says that they tamper with data this much
In reality, they do vastly more data tampering than they admit. The graph below overlays the graph above on the current final monthly minus raw.
It gets worse though, the final minus daily raw will be even larger than the monthly data. But most disturbing is the TOBS adjustment. According to Menne et al 2009, the TOBS adjustment hasn’t changed from USHCN 1, which showed no increase after 1990. yet now we see continuing TOBS adjustments (blue below) from 1990 to the present.
The 1990s station data hasn’t changed. The algorithm hasn’t changed. Why has the adjustment changed?
None of this makes any sense. They are adding to their adjustments for political reasons, not scientific ones.