dejo este pdf que analiza las estaciones de superficie en estados unidos, y las desmerece bastante,

aparte de cuestionar las medidas, de este documento se pueden sacar buenos aportes para hacer buenas mediciones,

Is the U.S. Surface Temperature Record Reliable?

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But how do we know if global warming is a problem if we can't trust the temperature record?
This report, by meteorologist Anthony Watts, presents the results of the first-ever comprehensive review of the quality of data coming from the National Weather Service's network of temperature stations. Watts and a team of volunteers visually inspected and took pictures of more than 850 of these stations. What they found will shock you: We found stations located next to the exhaust fans of air conditioning units, surrounded by asphalt parking lots and roads, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat. We found 68 stations located at wastewater treatment plants, where the process of waste digestion causes temperatures to be higher than in surrounding areas.
In fact, we found that 89 percent of the stations – nearly 9 of every 10 – fail to meet the National Weather Service's own siting requirements that stations must be 30 meters (about 100 feet) or more away from an artificial heating or reflecting source.
The conclusion is inescapable: The U.S. temperature record is unreliable. And since the U.S. record is thought to be "the best in the world," it follows that the global database is
likely similarly compromised and unreliable.