The previous post showed that changes to weather station data between CRUTEM3 and CRUTEM4.6 are responsible for converting the Hiatus into a warming trend. Here I look into some examples of those changes. I first looked for big changes in the monthly ‘normal’ values between 1961 and 1990. This identified some inconsistencies.
WMO identifiers are supposed to be fixed locations but Station 218240 has been changed and moved thousands of miles between CRUTEM3 and CRUTEM4.6. Despite this several temperature measurements remain exactly the same, which is simply impossible!
At the other extreme we have stations whose values have changed significantly
136 stations have seasonal monthly normals that have changed by more than 1C between CRUTEM3 and CRUTEM4.6. In some cases eg. Los Angeles, the station has moved in altitude going from downtown to Pasadena. However, others like Miami apparently are the same station but record completely different monthly mean temperatures going from CRUTEM3 to CRUTEM4.
Maybe this is a different station in another location since Miami is flat. However if so then this just demonstrates how great the variability is, even within one city.
What I think this really highlights is the lack of (available) metadata describing CRU station changes and updates, plus at least one data quality control issue. This doesn’t explain why the post 1998 warming trend changed.