Wednesday, March 3, 2010


Before doing Part II on looking for the UAH January anomaly in the raw AMSU data, I figured I'd clear the boards regarding "stuff you should know when looking at data". This post covers noise. There's one other post, the AMSU Limb Adjustment, which I'll do after this one.

There's actually several definitions of noise. In this post we're going to go with noise being anything that significantly changes the signal we're interested in.

You can get noise in a signal by adding additional data to it that's not related to the original signal, which I think everyone knows. But you can also get noise in a signal by taking out data that is related to the original signal. That's not as obvious and it's why I added the graphic showing loss of information degrading a signal into noise.

Creating noise both by adding data and by taking out data is related to my post examining channel 5, footprint 15. In that post, I tried to find validity for UAH's large January, 2010 anomaly by looking at channel 5, footprint 15. That footprint and footprint 16 require almost no limb adjustments to their readings. What they read is very close to the actual temperature.

This is the reason I picked that channel and footprint. It has the smallest chance of adding noise due to any invalid statistical limb adjustments.

The drawback to using only that footprint is I could have very easily created noise by limiting myself to only that footprint. There may be important information in the other footprints that was overlooked.

I'm aware of this problem and it's why we're going to continue our search for evidence of the January anomaly in the raw data. But I thought it was important for readers to be aware of it too.

Previous Posts In This Series:
Proof That Temperature Area Determines Temperature Anomaly
Trying To Find The UAH January Anomaly In The Raw Data, Part 1 Of 2
Overview Of The Aqua Satellite Project, Update 1 Features
Aqua Satellite Project, Update 1 Released
Spot Checking The Spot Check
NASA, UAH Notified Of QA Spot Check Findings
About The Aqua Satellite Project
UAH January Raw Data Spot Check
So, About That January UAH Anomaly
A Note On UAH's High January Temperature

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