My favorite USHCN hack to bring temperatures up, is called the “time of observation bias.” It is based on the idea that all 50,000 or so USHCN station owners have been morons.
It is a misnomer. The correct name for it would be “time of reset bias.” It doesn’t make any difference what time you record the temperature, the concern is what time you reset the thermometer.
Suppose you are brain-damaged and reset your min/max thermometer at 3PM every day. On Tuesday the high is 60F, which occurred right at 3PM. At 6PM a cold front comes through and the temperature drops to 10F and stays there for 24 hours. On Wednesday, you put on your heavy jacket and mittens go outside and look at your min/max thermometer. It says that the high temperature was 60F, which is off by 5o degrees.
The opposite problem occurs if you reset your thermometer at 6AM. Only a complete imbecile would not recognize the problem, which is why almost everyone who operates a min/max thermometer understands that you need to reset the thermometer every night.
The TOBS adjustment assumes that there used to be a lot of stupid people who reset their thermometers in the afternoon, and now there are a lot of stupid people who reset their thermometers early in the morning.
What I find interesting is that Hansen’s adjustments have been getting exponentially larger, based on the assumption that people are getting exponentially more gullible.
Nice explanation of TOBs. Any idea where to get specific info on how they do the adjustment?
Yes, has anyone polled the people who have kept these records to see what procedures they actually followed?
Sorry, I just realized I’m asking a different question.
This is a little OT, but in considering the vanishing decline from 1940 to 1970 or thereabouts, it’s worth noting that temperatures were not the only data under consideration when people discussed this in the late 60’s and early 70’s. People were also reporting a contraction of the growing season. I haven’t heard of any biases identified regarding this kind of data. (Not yet anyway. Maybe someone will propose a “TOGS bias” to take care of this issue.)
GISS guess… Gross!