Global climate change
How accurate are satellite measured temperatures of the troposphere?
1/19/2016, 10:32:34 AM
Yale Climate Connections recently put together a short video (see below) about the accuracy of the satellite measured temperature database of the lower troposphere, which covers a large portion of the globe.
The two main sources for this satellite measured temperature data is the University of Alabama at Huntsville (UAH) and Remote Sensing Systems (RSS). The satellite database goes back to 1979.
University of Alabama at Huntsville (UAH) global temperature anomaly plot of the lower troposphere since 1979.
Remote Sensing Systems (RSS) global temperature anomaly plot of the lower troposphere since 1979.
In the video, which was put together by Peter Sinclair, a number of climate experts make comments about the challenges of measuring temperatures using satellites.......
How Reliable are Satellite Temperatures. Video courtesy Yale Climate Connections and YouTube.
According to Dr. Michael Mann (Penn State), the satellite temperature record has actually been subject to more adjustments than the surface record.
Mann also states that the global satellite temperature record has been shown to have a bias of showing too little warming.
Studies have shown that satellite data was not properly interpreted. Atmospheric friction slows satellites down, causing them to lose altitude (1 km loss of height per year). In order to derive atmospheric temperature, scientists need to know the altitude of the satellite. Without the correct altitude, the temperature results can become distorted.
Satellite drift can also cause problems. Temperatures that were earlier analyzed at 2pm where a few years later being analyzed at 6pm, which made it look like there was cooling, when in fact there was no cooling.
UAH corrections were made, but still underestimated the warming, according to Dr. Kevin Trenberth (NCAR)
According to Dr. Andrew Dessler of Texas A&M, satellites actually measure radiance and not temperature. In order to determine temperature from the radiance the UAH/RSS team's use a "retrieval algorithm", which is essentially a model, according to Dessler. Unfortunately, that model has repeatedly been shown to be in error.
One reason why satellite measured anomalies are significantly lower than the surface measured temperatures is the fact that the satellite temperatures are measured against the 1981-2010 mean, whereas the NASA surface database is measured against the lower 1951-1980 mean and the NOAA database is measured against the 20th century average.
What should we do?
By looking at a longer time period you get a better idea of the overall temperature trend, said Dr. Carl Mears from RSS.
Mears stated that it is best to look at all of the data sets (satellite and surface) and not just trust the satellite database by itself in order to get the clearest picture of global temperature trends. It's also not just the temperature database that's telling us that the planet is warming as there are many more indicators.In addition to temperatures, increases in atmospheric water vapor, sea level changes, heat content of the ocean, sea ice etc. are telling us that the planet is warming and that natural causes cannot explain all of this warming, according to Dr. Ben Santer of the Livermore National Laboratory.
Global land/ocean surface temperature record from different sources.....
NOAA global land/ocean combined surface temperature anomalies since 1880.
HadCrut4 (UKMET) global land/ocean combined temperature anomalies.
JMA (Japan) global temperature anomalies.
Berkeley Earth global temperature anomaly analysis.
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