Saturday, 18 February 2012

AIRS Videos Updates.

I have updated the January and December AIRS videos. From now on the series will be updated regularly, I'll aim to do it each month around the time of release of the latest image, which should be sometime in the second week of the month.



One problem for those linking directly to videos from their blog/message board pages is that the URLs will change as I update each video, this is because Youtube offer no 'replace' function. So I have to delete and post a new video. However the new URLs will be posted on the original page as the videos are updated.

I won't be posting to announce updates, although comments may sometimes be appropriate.  Apropos of which:

January shows the highest AIRS methane concentration retrieval for any month in the series. I've been poring over NCEP/NCAR and can't see any obvious reason for this. That does not mean (as some have been implying) that this is the start of some cataclysm. Methane levels in the atmosphere are as a result of fluxes - generation, destruction, movement in the atmosphere. I've previously noted how AIRS suggests an increase in methane for some months after 2007's sea-ice crash, January being one of those months. However in terms of any individual anomaly absent decisive information it is just as likely that atmospheric mixing and rates of destruction due to colder/warmer air are key players as it is that there is a larger flux from the surface. Furthermore for those claiming it is the start of a massive increase, they would do well to follow the images into the summer months, when warmer air temperatures increase OH radical reaction rates, leading to destruction of the methane and reduced anomalies concentrations.

6 comments:

Anonymous said...

Chris,

All you wrote is correct, but I disagree with using the word "anomaly". I am sure you understand that anomaly is a deviation from "normal", and by normal we may understand the seasonal averages during some previously chosen period, say 2002-2007. So, the expected (and unavoided) decline after March 2012 does not have any common with "anomaly".

Anonymous said...

Chris,

All you wrote is correct, but I disagree with using the word "anomaly". I am sure you understand that anomaly is a deviation from "normal", and by normal we may understand the seasonal averages during some previously chosen period, say 2002-2007. So, the expected (and unavoided) decline after March 2012 does not have any common with "anomaly"

Chris R said...

Thanks Anon.

You are correct, it was the wrong word to use, I've ammended to 'concentration'.

Hank Roberts said...

> can't see any obvious
> reason for this

Most of the sites related to AIRS have contact links or a way to ask questions, and usually some info about the reliability of data they post and how to interpret it -- did you ask any of them what they think?

Anonymous said...

Regretfully, a so primitive CH4 data set from AIRS is now the only operational source of information about the Central Arctic. Ideal one would be a network on drifting ice (say, automatic bouyes). But we have what we have.

The reality is a monotonous increasing of CH4 anomaly during last 6-7 months. There have not been so long increase since 2002 and so fast since 2009. The question: is it a start of long-term emission from the oceanic bottom? No other sources of methane during winter time are proposed so far. I am highly skeptical about any algae activity in winter.

The answer may appear only after a significantly long time of monitoring(~ 1 year). However, February is coming to the end. The anomaly in February would be a first test for this opportunity.

What next? March-April. Normally (but NOT every year) in March and/or April central Arctic is full of methane. This can be explained by blooming algae. Why not every year? I am not a biologist, but I know from my anecdotal observations that pine blooms not every year, maybe every second year. IMHO, this is due to large efforts need for plants for breeding. It should relax before a new cycle.

Coming back to NH-SH-global anomaly plot, it is interesting that the previous significant NH-only increase of methane took place in March-April 2009 (maximum of anomaly does not coincide with maximum emission – May 2009, maximum emission coincides with the maximum monthly change in anomaly, i.e., March-April). Now the maximum rate of anomaly increase happened between December and January. Is it catastrophic? NO! This increase can be easily induced by a modest 20 Mt of methane per year. Is it dangerous? YES! This is the FIRST sign of significant emission from the bottom. There are no hopes that the water temperature would decline during coming years. Rather, it is expected to rise. So, the most likely scenario is continuing methane growth.

Optimistic view: contribution of combined clathrate/continental permafrost would be less than that from CO2 if the the rate of increase would be the same as now. Pessimistic view: clathrates will be emitting methane more and more. Apocalyptic view: tomorrow we will die. Choose to your taste. Science can not help you at this stage.

Chris R said...

Is it possible that the apparent increase over the central Arctic is not due to emissions from the central Arctic? i.e. emissions from under the sea-ice.

It seems apparent that there is an increase over the Arctic and sub-Arctic landmasses. Over the ocean temperatures are kept warmer due to open water. However over the central Arctic pack-ice the temperatures are pegged down by the ice, insulating atmosphere from the ocean surface. So whatever fluxes go into the atmosphere over the ice-pack will not be subjected to the OH reaction as much as those over the open ocean, potentially leading to an apparent build up of methane over the ice-pack.

I think that while increase in atmospheric flux from boreal land masses is 'masked' by the rate of OH driven methane destruction over the ocean, the same increase can lead to an apparent increase of methane concentration over the ice-pack.

As for the wider pattern of increased methane over the landmasses, notably the Russian Federation, I suspect that this is due to emissions from the surface. This is purely because this pattern is a repeated feature of the Arctic winter throughout the series of AIRS retrievals.

I think the AIRS videos support the idea that this period of increase was probably started by the sea-ice crash of 2007. To see periods of high concentration such as this January does not surprise me.

I disagree about the available science not being able to guide us as to whether Arctic methane emissions will be catastrophic or chronic. From my reading it is most likely we face a chronic release (see my earlier posts, here and here. However I do see the situation as worrying, see here.