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How NOT to measure climate change.
14 August 2007Seriously, place a weather station next to a trash burning barrel? The weather station was there long before the burning barrel.
The property management person I spoke with said the tennis court and condos was built in the early 80’s.
Here’s the graph of this station. Is it hot in here?
These pictures and graphs and a lot more can be found on the Watts Up With That: Weather Stations
It would be funny if these stations were not being used to influence global climate studies.
There are hundreds of weather stations located in sewage treatment plants. Makes sense, it is government land, some one is always there to monitor and keep an eye on the equipment. But sewage treatments plants give off heat. Kinda of a natural byproduct you see.
You gotta see this one, yes that is a working jet.
Now a word on measuring temperatures. Frankly it is not easy, at least not down to the accuracies these guys are claiming. If the electronic thermometer is not calibrated regularly which to me means at least twice a year, accuracies greater than 1 or 2 degrees is not to be expected.
I have a hard time trusting that the data is accurate to the level of identifying 1 or 2 degree changes over decades. This is especially true since the techniques of making these measurements have changes over that time frame.
I could not say it any better than Anthony Watts said at the end of the post in response to a comment made by an electronics engineer named Lon.
Lon, thank you for the comments. FINALLY somebody who understands the kind of biases that creep into temperature measurements!
I’m innately familiar with National Semi’s LM34 and it’s accuracy problems. One of my early jobs at the university as a research assistant was to create remote electronic weather stations. I soon learned how inaccurate mand electronic devices can be in temperature measurement.
The problem with the National Weather Service temperature data sets (and world data sets too) are that they are full of biases that I’m not sure have been accurately accounted for. People such as Jim Price, from CSUC who is on the IPCC say they have been, yet nobody has shown me any hard evidence of such. I’d be a lot less skeptical if I could see how the IPCC accounted for temperature measurement biases. But they won’t share.
Some people that I try to explain this to accuse me of splitting hairs. But these bias problems in temperature measurement are quite real.
What works against my arguments about the difficulty in getting accurate temperature records is the everyday simplicity of temperature and its common measurement. We live by temperature, we have it reported constantly, we all have thermometers at home, we measure our children’s fevers with thermometers, we barbeque with thermometers.
Measuring temperature is easy right? You just stick the thermometer in whatever gas, liquid, or solid you want to measure the temperature of and voila’ there it is. People tend to think of thermometers as perfect devices. Some are close, especially when taking measurements ina closed system, like a fermentation vat at Sierra Nevada.
But in an open system in our atmosphere, there are many many more biases that can affect the measurement within a few inches or feet of the thermometer. Here’s just a few:
- Reflected sunlight from nearby building or objects
- Re-radiated infrared from nearby cement or asphalt surfaces or the ground itself (which is why airports make terrible places for temperature measurement)
- The structure that the thermometer is mounted to, can conduct heat to the thermometer
Now add to that:
- Accuracy of the thermometer itself
- Linearity of the thermometer over its measurement range
- Long term repeatability of the thermometer’s accuracy
- Long term repeatability of the thermometer’s linearity
And then we have urban effects such as:
- Localized vegetatation removal or addition over time
- Localized building changes over time
- Localized asphalt or concrete surfaces addition or removal
And finally within the Global Temperature data set we find:
- Changing the location of the weathet station thermometer
- Changing the thermometer itself at some point - i.e. repair/replace
- Changing the thermometer type, from mercury, to electronic
- Changes in thermometer shelter, different types of paint over time, all which have different absorptive and reflective properties.
Ok with all these biases that you have to account for to make long term temperature measurement reflect the true temperature of the location, can you be absolutely sure of the data? Especially when you are looking for trends that may be 1 degree or less over 50-100 years?
Or letes try a thought experiment Lon, you’ve been commissioned by the IPCC to make a new thermometer for use around the world at climate measurement stations. As an electrical engineer, could you design an air temperature thermometer that is:
- Linear to with 0.5% over a temperature range of -20F to 120F
- Accurate to within 0.1 degree over that same range
- Repeatable in linearity and accuracy defined above for a period of 20 years. Or even 10 years.
- Identical withing the specs above, so that if one fails, it can be immediately swapped with another one from parts stock with no worry about introducing bias
Ok there’s your challenge. Could you do it?
2 Responses to “How NOT to measure climate change.”
January 6th, 2008 at 6:45 am
One things that rives me nuts about the AGW types is they never report the error bars on their data. Even if one ignores all the environmental factors affecting temp measurements and just calculated the accumulated error due to the thermometers themselves that have been used to collect this data for the past 50 years, what would it be? Based just on my gut feel for these things, I’m willing to bet the accumulated standard error is between 1 and 2 degrees.
January 6th, 2008 at 9:44 am
It’s like all the rules of scientific inquiry we were taught somehow doesn’t apply.
The Y2K bug was found in the NASA data. Only time I’ve ever seen the Y2K bug. Of course it was SEVEN years after Y2K!.