Bishop Hill via correspondent Gras Albert noted this event early today:
I looked through the entire satellite record, and couldn’t find any similar event. That meant it was either unique, or indicative of a technology failure like we witnessed with NSIDC when one of their sensor channels gave out. I asked Dr. Roy Spencer if he thought this was real, and he responded with an update, seen below:
March 25th, 2013By Dr. Roy Spencer
Many people have noted on the satellite temperatures webpage the plunge in temperatures as recorded by AMSU channel 5 on the Aqua satellite. Since it looked pretty suspicious, I decided to investigate.
The following plot shows 3 satellites’ global AMSU5 measurements (Aqua, NOAA-15, and NOAA-18) that I computed this morning from the raw orbit files. The dates run from Feb. 1 through yesterday, March 24:
Clearly, Aqua AMSU ch 5 is now “out to lunch”. The reason why the plunge in Aqua temperatures in the above plot is so much stronger than what is displayed on the daily update website is that the latter shows running 3-day averages, and is only updated through March 23.
We knew that this channel has been slowly failing for a long time, which is why we have not been using it in our monthly updates. We will discuss the possibility of switching to the NOAA satellites on the website, although since the site is NASA-funded, they are reluctant to spend resources on NOAA satellite data. But, given the popularity of the page, we will work something out even if we have to make our own web page.