Thursday, February 25, 2010

NASA, UAH Notified Of QA Spot Check Findings

I've sent off the results of my QA Spot Check to the Aqua team at NASA and the Dr. Christy and Dr. Spencer at UAH. I couldn't find anything wrong with my results, so it's time to let the professionals have their input.

Here's a copy of the text that was sent:
I'm writing with questions regarding the January, 2010 Aqua satellite AMSU Level 1B data. I checked various QA flags in the data and found the following results:

● Of the 7410 files containing January data, 7386 of them had their automaticQualityFlag marked "suspect" and another 24 of them had the flag marked "failed". None passed QA.
● Of the 7386 suspect files, all of them had a "Good Data" percentage of 93.33334 percent. Here, "Good Data" is taken as the result of subtracting bad data, special data, and missing data from total data. "Good Data" is then divided by total data to get the percentage of "Good Data".
● Of the 333,450 Channel 4 readings for January none of them passed QA. All of them in the files marked "suspect" had been marked as failing QA and, obviously, the ones in the files marked "failed" were in files that failed QA and should not be used.

My questions are:

● Is it considered normal to have zero Level 1B AMSU data files for a month pass QA?
● Is it normal for all Level 1B AMSU data files for a month to have the exact same numbers for bad data, missing data, special data, and total data?
● Doesn't the statistics engine used for AMSU limb adjustment require valid data from channel 4 in order to correctly adjust channel 5 data?

Additionally, I asked Dr. Christy and Dr. Spencer if channel 5 from Aqua's AMSU is used to produce UAH anomalies. In an article on WUWT, Dr. Spencer said it is, but I just wanted to double check to make sure I understood correctly.

Previous Articles In This Series:
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

How the UAH Global Temperatures Are Produced


  1. I read your blog since some time.

    Thank you for your great work. I appreciate it very much, even if i do not post frequently comments.

    I am interestet in the above answer, too.

    Greetings from Germany

  2. I'm glad to see that you have gone ahead and asked Christy and Spencer about your findings.

    You may have found a significant problem. More likely, you have just gotten tripped up by a programming error, an error in the documentation, or corrupted files have been posted.

    I'm looking forward to seeing their replies.

    Both appear to be solid, open minded scientists seeking to advance our knowledge. I'm betting that you will get a rapid, substantive and informative response.

  3. Yeah, I wanted to move quickly to allow them the chance to respond. I certainly didn't want to wait till after the weekend and have this just hanging out there the whole time.

    But I will say I did a spot check on my spot check, meaning I manually checked the results by viewing the binary data in the official viewers and the text version in a text editor. The QA values that my code saw are really there, they're not artifacts of bugs in the code.

    So I'm expecting an answer along the lines of "Yes, technically channel 4 fails every time. This is because we mark it failed due to a known problem. That known problem can be handled and correct results obtained by using procedure XYZ".

  4. THANK YOU for all your hard work and detailed analysis... as I read your message text I could almost hear the sound of the proverbial hitting the fan.

    I greatly admire you open and honest approach and trust you will receive open and honest replies.

    I wish you patience and fortitude so that you can fully audit the process all the way to the calculation of a monthly global temperature anomaly.

    Personally, I am far more cynical... my BS detectors were activated long ago... especially as the NASA brand is so tarnished... I suspect that much of the detailed work is outsourced to all sorts of technical engineers... so the good Doctors will probably only have "an understanding" of what is actually happening because they have left the "technical details" to the "specialist engineers"... it is even possible that the same outsourced "technical team" is processing the satellite and land based temperature records.

  5. Any response yet ??

    Your question is a relatively straightforward one that they should have been able to answer relatively easily and quickly.