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Author Topic: Hydroxyls missing, gun has fired ?  (Read 5065 times)

morganism

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Hydroxyls missing, gun has fired ?
« on: September 13, 2014, 09:45:39 PM »
Nature pub.
N and S hemispheres appear to have same amount of OH.
Since North produces much more nitric oxides, the precursor of OH, then something is using it up.

http://m.phys.org/news/2014-09-evidence-interhemispheric-hydroxyl-parity.html

More information: "Observational evidence for interhemispheric hydroxyl parity." P. K. Patra, et al. Observational evidence for interhemispheric hydroxyl-radical parity. P. K. Patra, M. C. Krol, S. A. Montzka, T. Arnold, E. L. Atlas, + et al. Nature 513, 219-223 DOI: 10.1038/nature13721

jai mitchell

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Re: Hydroxyls missing, gun has fired ?
« Reply #1 on: September 14, 2014, 08:28:34 AM »
Fracking


It is all about the 4% to 8% total production volume leakage rates.  The reduction in Russian oil production (and methane release) in the mid 90's was the reason for the cessation of methane growth at that time.  Now it has resumed.

as the Hydroxyl sink is scavenged, the atmospheric residence time is extended.  This will push the 20 and 100 year CO2 equivalency values for methane from 85 and 20 times to 105 and 28 times.

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ccgwebmaster

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Re: Hydroxyls missing, gun has fired ?
« Reply #2 on: September 14, 2014, 06:36:10 PM »
as the Hydroxyl sink is scavenged, the atmospheric residence time is extended.  This will push the 20 and 100 year CO2 equivalency values for methane from 85 and 20 times to 105 and 28 times.

Including direct and indirect aerosol effects? Seem to recall Shindell et al 2009 had the 20 year GWP at 105x including those - so the final value would then be higher - presuming that the sink were compromised.

AbruptSLR

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Re: Hydroxyls missing, gun has fired ?
« Reply #3 on: September 14, 2014, 08:11:34 PM »
The attached image is Figure 2 from Shindell et al (2009) indicates 100-year GWP values for methane of 25 without aerosol effects, and 34 with both direct and indirect aerosol effects.  Also, if you read the caption for this figure you will see that the 20-year GWP value for methane is 79 without aerosol effects and is 105 with both direct and indirect aerosol effects (see linked pdf also)

Shindell, D.T., Faluvegi, G., Koch, D.M., Schmidt, G.A., Unger, N., and Bauer S.E. (2009), "Improved Attribution of Climate Forcing to Emissions" Science, Vol. 326 no. 5953 pp. 716-718, DOI: 10.1126/science.1174760.

http://saive.com/911/DOCS/AAAS-Aerosols-not-CO2-Cause-Global-Warming.pdf

Howerver, the AR5 (2013) only cites a 20-year GWP for methane of 86 (see below):

Methane GWP value and lifetime from 2013 IPCC AR5 p714
Lifetime: 12.4 years
GWP over 20 years: 86
GWP over 100 years: 34

However, if you are truly concerned about the potential influence of the loss of atmospheric hydroxyl ions on the GWP of methane then you should download, and read, the following linked reference by Isaksen et al (2011), with an open access pdf:

Isaksen, I. S. A., Gauss M., Myhre, G., Walter Anthony, K. M.  and Ruppel, C.,  (2011), "Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions", Global Biogeochem. Cycles, 25, GB2002, doi:10.1029/2010GB003845.

http://onlinelibrary.wiley.com/doi/10.1029/2010GB003845/pdf
« Last Edit: September 14, 2014, 08:44:42 PM by AbruptSLR »
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jai mitchell

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Re: Hydroxyls missing, gun has fired ?
« Reply #4 on: September 15, 2014, 08:18:14 AM »
http://www.ess.uci.edu/~cdholmes/pubs/holmes2012b.pdf

Future methane, hydroxyl, and their
uncertainties: key climate and emission
parameters for future predictions

Accounting for both direct and indirect effects, the methane RF efficiency, Fe, is
15 618mWm−2 ppm(CH4)−1 in steady-state. A 1 Tg pulse emission of methane raises
the atmospheric abundance by  = 0.364 ppb, which decays at a rate f CH4
, where
f = 1.33 is the methane feedback on its lifetime. We use CH4
= 9.14 yr (Prather et al.,
2012). Neglecting delays between emission time and stratospheric impacts, the 100-yr
absolute GWP is f CH4Fe = 2.75mWyrm−2, compared to 0.087mWyrm−2 for CO2.
20 Thus, the methane GWP100 is 31.6. Our result is higher than several previous reports,
generally near 25 (Forster et al., 2007; Fry et al., 2012), mainly because we include
stratospheric ozone effects, but also because the updated and longer methane lifetime
used here (Prather et al., 2012)(Reactive greenhouse gas scenarios: Systematic exploration
of uncertainties and the role of atmospheric chemistry
).

The prediction begins with the best estimate of present-day
(2010) methane budget, including natural and anthropogenic emissions, and lifetimes
for all loss processes, using the method of Prather et al. (2012). The scenario specifies
future anthropogenic methane emissions and we assume natural emissions could
change ±20% (1) by 2100.

_____________

My notes have a reference to a recent paper studying a methane pulse on atmosphere chemistry and the hydroxyl sink.  In my notes it states a CH4 residency increase from 9.2 years average to 17.6 years average.  Any clue where I got that from?

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jai mitchell

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Re: Hydroxyls missing, gun has fired ?
« Reply #5 on: September 17, 2014, 09:07:50 PM »
Satellite Analysis of U.S. Methane emissions shows anomalous release in southwest states equivalent to 10% of total u.s. EPA estimated emissions.

http://onlinelibrary.wiley.com/doi/10.1002/2014GL061503/abstract

Four Corners: the largest US methane anomaly viewed from space†

Kort, et. al.
GRL, DOI: 10.1002/2014GL061503


Quote
Results indicate the largest anomalous CH4 levels viewable from space over the conterminous US are located at the Four Corners region in the Southwest US. Emissions exceeding inventory estimates, totaling 0.59 Tg CH4/yr [0.50-0.67; 2σ], are necessary to bring high-resolution simulations and observations into agreement. This underestimated source approaches 10% of the EPA estimate of total US CH4 emissions from natural gas.
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AbruptSLR

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Re: Hydroxyls missing, gun has fired ?
« Reply #6 on: September 29, 2014, 02:11:10 AM »
The linked reference indicates that it is easier to produce hydroxyl radicals in the atmosphere, than previously expected:

Fang Liu, Joseph M. Beames, Andrew S. Petit, Anne B. McCoy, and Marsha I. Lester, (26 September 2014) "Infrared-driven unimolecular reaction of CH3CHOO Criegee intermediates to OH radical products", Science, Vol. 345 no. 6204 pp. 1596-1598 DOI: 10.1126/science.1257158

http://www.sciencemag.org/content/345/6204/1596

Abstract: "Ozonolysis of alkenes, an important nonphotolytic source of hydroxyl (OH) radicals in the troposphere, proceeds through energized Criegee intermediates that undergo unimolecular decay to produce OH radicals. Here, we used infrared (IR) activation of cold CH3CHOO Criegee intermediates to drive hydrogen transfer from the methyl group to the terminal oxygen, followed by dissociation to OH radicals. State-selective excitation of CH3CHOO in the CH stretch overtone region combined with sensitive OH detection revealed the IR spectrum of CH3CHOO, effective barrier height for the critical hydrogen transfer step, and rapid decay dynamics to OH products. Complementary theory provides insights on the IR overtone spectrum, as well as vibrational excitations, structural changes, and energy required to move from the minimum-energy configuration of CH3CHOO to the transition state for the hydrogen transfer reaction."

See also:
http://www.reportingclimatescience.com/news-stories/article/key-atmospheric-detergent-reaction-seen-in-the-lab.html
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Laurent

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Re: Hydroxyls missing, gun has fired ?
« Reply #7 on: January 19, 2015, 05:38:53 PM »
Spectroscopic signatures of ozone at the air–water interface and photochemistry implications
http://www.pnas.org/content/111/32/11618.abstract

Quote
Ozone is one of the most important atmospheric trace gases in Earth's atmosphere. It can interact with water in the gas phase as well as with water in cloud droplet surfaces. This work identifies unique spectral signatures for ozone adsorbed at the surface of cloud water droplets in the UV and visible light domains. The adsorption process itself is thermodynamically spontaneous. With this information, it is found that the photochemistry of ozone at the air–water interface is a significant previously unidentified source of OH radicals generated at the surface of clouds. The broader implication is that the surface of cloud water droplets can be an active chemical reactor that contributes to the oxidizing capacity of the troposphere on a global scale.

AbruptSLR

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Re: Hydroxyls missing, gun has fired ?
« Reply #8 on: January 20, 2015, 02:07:37 AM »
Most of this is re-posted from the "Forcing" thread in the Antarctic folder:

The linked reference (with an open access pdf) emphasizes our current poor understanding of the current and future atmospheric compositions with regard to ozone and hydroxyl ions as emphasized by the following extract showing that the hydroxyl driven lifetime for methane predicted by different models differ by a factor of 2 (which is not very reassuring).

Extract: "The oxidation capacity of the atmosphere remains poorly characterised in a number of environmentally sensitive regions, with an order of magnitude difference between measurements and models. Both measurements and our understanding of the key chemical processes have large uncertainties. One example of this lack of understanding is the uncertainty in future methane concentrations, with models predicting •OH driven lifetimes that differ by a factor of 2."

S. Madronich,   M. Shao,   S. R. Wilson,   K. R. Solomon,   J. D. Longstreth and   X. Y. Tang, (2015), "Changes in air quality and tropospheric composition due to depletion of stratospheric ozone and interactions with changing climate: implications for human and environmental health",  Photochem. Photobiol. Sci.,14, 149-169, DOI: 10.1039/C4PP90037E


http://pubs.rsc.org/en/content/articlelanding/2015/pp/c4pp90037e#!divAbstract

Abstract: "UV radiation is an essential driver for the formation of photochemical smog, which includes ground-level ozone and particulate matter (PM). Recent analyses support earlier work showing that poor outdoor air quality is a major environmental hazard as well as quantifying health effects on regional and global scales more accurately. Greater exposure to these pollutants has been linked to increased risks of cardiovascular and respiratory diseases in humans and is associated globally with several million premature deaths per year. Ozone also has adverse effects on yields of crops, leading to loss of billions of US dollars each year. These detrimental effects also may alter biological diversity and affect the function of natural ecosystems. Future air quality will depend mostly on changes in emission of pollutants and their precursors, but changes in UV radiation and climate will contribute as well. Significant reductions in emissions, mainly from the energy and transportation sectors, have already led to improved air quality in many locations. Air quality will continue to improve in those cities/states that can afford controls, and worsen where the regulatory infrastructure is not available. Future changes in UV radiation and climate will alter the rates of formation of ground-level ozone and photochemically-generated particulate matter and must be considered in predictions of air quality. The decrease in UV radiation associated with recovery of stratospheric ozone will, according to recent global atmospheric model simulations, lead to increases in ground-level ozone at most locations. If correct, this will add significantly to future ground-level ozone trends. However, the spatial resolution of these global models is insufficient to inform policy at this time, especially for urban areas. UV radiation affects the atmospheric concentration of hydroxyl radicals, ˙OH, which are responsible for the self-cleaning of the atmosphere. Recent measurements confirm that, on a local scale, ˙OH radicals respond rapidly to changes in UV radiation. However, on large (global) scales, models differ in their predictions by nearly a factor of two, with consequent uncertainties for estimating the atmospheric lifetime and concentrations of key greenhouse gases and air pollutants. Projections of future climate need to consider these uncertainties. No new negative environmental effects of substitutes for ozone depleting substances or their breakdown-products have been identified. However, some substitutes for the ozone depleting substances will continue to contribute to global climate change if concentrations rise above current levels."
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AbruptSLR

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Re: Hydroxyls missing, gun has fired ?
« Reply #9 on: March 30, 2015, 04:38:45 PM »
While acknowledging that Sam Carana is a controversial figure, & consequently I try to minimize my reposting of his images, the attached figure by Carana is simply reporting raw atmospheric methane concentration data with altitude for March 10th in 2013, 2014, and 2015 (so besides the risk that this date could be cherry picked) so I think that the message that it is conveying that the atmospheric methane concentration is increasing faster at higher altitudes (than lower) is an important trend to note.  This trend may very well be due to higher rates of hydroxyl ion depletion at higher altitudes resulting in a faster rate of methane accumulation at higher altitudes.  If so, we are not only seeing higher rates of methane emissions (both anthropogenic and natural), but also increasing residence time for methane in the atmosphere which is resulting in increasing Global Warming Potential, GWP, for methane in real-time (not some theoretical distant future).
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viddaloo

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Re: Hydroxyls missing, gun has fired ?
« Reply #10 on: March 30, 2015, 05:27:39 PM »
Sam wouldn't be so prominent with his graph production if the US Chamber of Commerce didn't 1) stop updating it's Mauna Loa CH4 graphs on Feb 7, and 2) *delete* all MetOp2 data after only 3 days.

If a normal guy wants CH4 stats, Sam's about the only source of recent data. Too bad the Methane Tracker had to close shop  :(
[]

AbruptSLR

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Re: Hydroxyls missing, gun has fired ?
« Reply #11 on: March 31, 2015, 01:09:22 AM »
This linked 2014 presentation cites the 100-yr GWP of methane as 32 (Drew Shindell cites a value of 35).

Michael Prather (2014): "Reactive Greenhouse Gas Scenarios: Uncertainties, Future OH and Methane"


http://climatemodeling.science.energy.gov/presentations/reactive-greenhouse-gas-scenarios-uncertainties-future-oh-and-methane


Abstract: "Knowledge of the atmospheric chemistry of reactive greenhouse gases is needed to accurately quantify the relationship between human activities and climate, and to incorporate uncertainty in our projections of greenhouse gas abundances. We present a method for estimating the fraction of greenhouse gases attributable to human activities, both currently and for future scenarios. Key variables used to calculate the atmospheric chemistry and budgets of major non-CO2 greenhouse gases are codified along with their uncertainties, and then used to project budgets and abundances under the new climate-change scenarios. This new approach uses our knowledge of changing abundances and lifetimes to estimate current total anthropogenic emissions, independently and possibly more accurately than inventory-based scenarios. We derive a present-day atmospheric lifetime for methane (CH4) of 9.1 å± 0.9 y and anthropogenic emissions of 352 å± 45 Tg/y (64% of total emissions). For N2O, corresponding values are 131 å± 10 y and 6.5 å± 1.3 TgN/y (41% of total); and for HFC-134a, the lifetime is 14.2 å± 1.5 y. Accurate prediction of future methane abundances following a climate scenario requires understanding the lifetime changes driven by anthropogenic emissions, meteorological factors, and chemistry-climate feedbacks. Uncertainty in any of these influences or the underlying processes implies uncertainty in future abundance and radiative forcing. We simulate methane lifetime in three chemical transport models (CTMs) ‰ÛÒ UCI CTM, GEOS-Chem, and Oslo CTM3 ‰ÛÒ over the period 1997‰ÛÒ2009 and compare the models' year-to-year variability against constraints from global methyl chloroform observations. Using sensitivity tests, we find that temperature, water vapor, stratospheric ozone column, biomass burning and lightning NOx are the dominant sources of interannual changes in methane lifetime in all three models. We also evaluate each model's response to forcings that have impacts on decadal time scales, such as methane feedback, and anthropogenic emissions. In general, these different CTMs show similar sensitivities to the driving variables. We construct a parametric model that reproduces most of the interannual variability of each CTM and use it to predict methane lifetime from 1980 through 2100 following a specified emissions and climate scenario (RCP 8.5). The parametric model propagates uncertainties through all steps and provides a foundation for predicting methane abundances in any climate scenario. Our sensitivity tests also enable a new estimate of the methane global warming potential (GWP), accounting for stratospheric ozone effects, including those mediated by water vapor: the 100-yr GWP is 32 (25% larger than past assessments)."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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