Figures 1-3 show the difference between Liverpool airport and Manchester airport for Tmax, Tmin & Tmean for the period 05Sep2001 to 22Mar2021 (7,139 days):
Tmax 0.4°C Liverpool warmer than Manchester:
Tmin 1.4°C Liverpool warmer than Manchester
Tmean 0.8°C Liverpool warmer than Manchester
This was to be expected due to their differing geographical locations. Liverpool being nearer to water, the Mersey estuary, and Manchester being inland.
From 25Mar2021 to 18Jul2021
Tmax 2.1°C: 1.7°C Liverpool warmer than Manchester
Tmin 3.4°C: 2.0°C Liverpool warmer than Manchester
Tmean 2.7°C: 1.9°C Liverpool warmer than Manchester
These are exceptionally large discrepancies in comparison to the long-term data:
What happened during the 19 hours of missing observations between the 23/24Mar2021? I suggest they have had new thermometers. I have tried phoning Air Traffic Control at Liverpool, who look after weather observations, on numerous occasions, without reply even after double and triple checking it was the right telephone number. An enquiry to the Met Office by Tony Brown received this reply:
"Thank you for your enquiry. I can confirm that we do have an observing site at Speke (Liverpool Airport), but aside from that I do not know whether the apparent break in observations on 24/25 March 2021 was due to new or replacement thermometers being installed, or for some other reason. The Land Observations team may be able to comment further (cc'd)."
Out of interest, "Speke" Liverpool airport was renamed "John Lennon" Liverpool airport 10 years ago.
Of course, no answer from the Land Observations team as yet.
The questions which arise; have they moved the recording equipment to a new site at the airport? Or have the changed the temperature measuring equipment? If they have had new thermometers, why were they not tested in parallel for a significant time to make sure they were compatible for use.
Call me cynical if you like, but this is a particularly good way of achieving the IPCC desired 1.5°C temperature increase, but they cannot blame it on CO2 this time.