Friday, October 7, 2011

AMSR-E failure and fallout

Update 17 October: The meeting last Tuesday gives little hope.  There will definitely be no data for weeks.  I don't know what prevents a conclusion of never.
original:
AMSR-E has failed and is probably permanently out of commission.  For most of you, that's merely news.  Perhaps a source of amusement and interest is now gone.  For me, since I use(d) it in my day job, AMSR-E failing means some real work.  Most of that work was already planned, but now it needs to be done more speedily.

As I've often said here, and even more often in 3d, data are messy and ugly.  One sort of ugliness is that instruments do not last forever.  When (not if) they fail, you have to turn to a different instrument.  Ideally, you already have the replacement in hand and have been running it regularly and intercomparing its results with your current main system and ensured that there are no differences other than those you wanted -- like better resolution on the new instrument.  The present situation is not ideal, so, as we usually do in science, I'm making the best of it that I can.  And making notes for what to do when I have a chance to rework the immediate fixes.

Step 1 was to bring back in to service an (even) older satellite data source that I used to use.  I stopped using it because it was hearing voices, which degraded the quality of the work I did.  On the other hand, using it is far better than having no data at all.  This is in hand, and will be officially operational tomorrow.

Step 2 is to develop a 'voice filter' for the data, to get around that problem.  Fingers crossed, tests today look promising.

Step 3 is to bring a new instrument in to use.  It's newer than AMSRE, but not as high resolution.  Plus there are some issues with biases as compared to the older record.  To bring it on line, these need to be reduced (possibly substantially), or, if we're very unlucky, characterized and my downstream users warned of the change (they already know about what's happening tomorrow, at least the immediately-to-hand folks).

AMSR-E did a good job.  Its designed life span was 5 years (maybe 6), and it gave data for about 9.5.  The real problem, for me at work, was not AMSR-E, but the fact that no successor was launched in that 9.5 years.  A launch of AMSR-2 is currently (last I heard from my spies) planned for February 2012, and the spies report that there's discussion of maybe moving up the launch date.  Fingers crossed.  On the other hand, for my work, even a launch tomorrow doesn't save me from steps 2 and 3 above and the work involved.  It takes time for a satellite to reach its working orbit, to be brought up to operational status for collecting data, for the data flow system on earth to start passing out the data to some locations, and some more for the data to come down to me in a form that I can use.  These are a matter of months (optimistically) to years (pessimistically).  So, again, cross your fingers.  If we're lucky, by this time next year, we'll have AMSR-2 in my work's operations.

Irrespective of my working life, the gap between AMSR-E and AMSR-2 just by its existence degrades the quality of the climate data record.  It makes impossible the direct inter-comparison and inter-calibration between the two instruments.  A few years down the road, we're looking at a larger scale example of that, as the next set of polar-orbiting satellites (JPSS is the acronym there, now, used to be NPOESS) was delayed by the 2011 budget, and looks likely to be delayed in the 2012 budget as well. 

Bottom line message:
It'll probably be a bit before I'm back to writing normally, including how my sea ice outlooks did (pretty well, actually; the high and low, I thought were high and low (5.0 and 4.4 vs. the observed 4.6), and the two model predictions were 4.8 and 4.6, vs. the observed 4.6).

If people are really interested in the gruesome details of what I'm doing at work, that I can keep writing about.  Any takers?  (bwah hah hah!)

10 comments:

t_p_hamilton said...

Any backup plan just in case the launch of AMSR2 fails?

Neven said...

I didn't even know about this and thought AMSR-E would be with us forever. What a shame. But luckily it didn't happen during the melting season.

Good luck, Robert!

Robert Grumbine said...

t_p:
After the cursing, gnashing of teeth, wailing, and such ...

Continue using the SSMI-S instruments that I'll have in our operations by (knock wood) next year. That's the 'step 3' above. Fortunately, at least 2 more launches for SSMI-S are already planned.

Thanks Neven. I agree about the melt season. If this had to happen, which, realistically, it did, this was about the best time of year for it to do so.

Artful Dodger said...

Hi Robert,

How feasible would it be to temporarily shut down the other instruments on Aqua, and spool up the antenna on AMSR-E for a (few day) campaign, much like was done to extent the mission of IceSat, once the problems were identified with it's lasers?

AMSR-E / AMSR2 calibration seems especially important, as is March sea ice extent. You comments appreciated!

Cheers,
Lodger

Kooiti Masuda said...

According to announcement from JAXA, the trouble with AMSR-E was increased friction and not a simple power shortage. They say they are still trying, but restarting (even temporarily) the sensor seems unlikely, unless they succeed in indentifying the cause of friction and mitigating it.

Robert Grumbine said...

Lodger:
As Dr. Masuda says, the problem here is different. Over the last year or two, it has taken increasing amounts of torque to make the sensor spin. This is important because the AMSRE is a conical scanner -- the antenna is spun in a circle. This gives us a consistent footprint size and angle of intersection with the earth, both very good things for users like me.

Last week, the torque required to keep it spinning properly became excessive, and the instrument was turned off.

Tomorrow (11th October, though I'm not sure which time zone) there'll be a meeting to decide what can be done with the instrument. The rest of us will know more then.

Since it isn't a matter of sending someone down to the shop for some lubricating oil, I'm not at all confident that they'll be able to bring it back in to service. If they can, I expect it to be short-lived, weeks-months.

Dr. Masuda:
Thank you for the link to a public announcement of the status. I had my information from back channels and wasn't sure that it would be ok to post the announcements publicly.

jyyh said...

Sorryu nto hear of your loss... though I must ask because some transarctic passengers could film the degardation of arctic sea ice, why would the resu7lot be any different from that of the satellites??

L Hamilton said...

Any update regarding efforts to continue the sea ice time series by using other sources? Is that proving more difficult than hoped?

Robert Grumbine said...

Oops. Thought I'd mentioned already -- the fall back to using SSMI from DMSP F-15 occurred on the 7th at work. We've now got the global coverage again, but still have the questions of continuity and resolution.

jyyh said...

Dear me, seems I've been writing after an evening out... I likely meant to say it's not very easy or maybe even possible to have a comprehensive coverage by using aeroplanes as the regular cameras capabilities are blocked by clouds...