Quantifying the Causes of Differences in Tropospheric OH Within Global Models

The hydroxyl radical (OH) is the primary daytime oxidant in the troposphere and provides the main loss mechanism for many pollutants and greenhouse gases, including methane (CH4). Global mean tropospheric OH differs by as much as 80% among various global models, for reasons that are not well underst...

Celý popis

Uloženo v:

Podrobná bibliografie
Vydáno v:	Journal of geophysical research. Atmospheres Ročník 122; číslo 3; s. 1983 - 2007
Hlavní autoři:	Nicely, Julie M., Salawitch, Ross J., Canty, Timothy, Anderson, Daniel C., Arnold, Steve R., Chipperfield, Martyn P., Emmons, Louisa K., Flemming, Johannes, Huijnen, Vincent, Kinnison, Douglas E., Jean-Francois, Lamarque, Mao, Jingqiu, Monks, Sarah A., Steenrod, Stephen D., Tilmes, Simone, Turquety, Solene
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	Goddard Space Flight Center Wiley Blackwell (John Wiley & Sons) 16.02.2017 Blackwell Publishing Ltd American Geophysical Union
Témata:	Aerosols Air pollution Aircraft Chemical transport Chemistry Climate Climate models Daytime Detection Earth Resources And Remote Sensing Environment Pollution Fields Gases Geophysics Greenhouse effect Greenhouse gases hydroxyl radical Hydroxyl radicals Intercomparison Isoprene Mathematical models Meteorology And Climatology Methane methane lifetime Neural networks Nitrogen compounds Nitrogen dioxide Oxides Oxidizing agents oxidizing capacity Photolysis Pollutants POLMIP Regional variations Remote sensing Sciences of the Universe Statistics And Probability Transport Transportation models Transportation networks Troposphere tropospheric chemistry Surface Measurements And Models Hydroxyl Radical (oh) Remote Sensing Chemistry Of Climate oxidizing capacity OH hydroxyl radical tropospheric chemistry methane lifetime POLMIP
ISSN:	2169-897X, 2169-8996
On-line přístup:	Získat plný text
Tagy:	Přidat tag Žádné tagy, Buďte první, kdo vytvoří štítek k tomuto záznamu!

Popis
Shrnutí:	The hydroxyl radical (OH) is the primary daytime oxidant in the troposphere and provides the main loss mechanism for many pollutants and greenhouse gases, including methane (CH4). Global mean tropospheric OH differs by as much as 80% among various global models, for reasons that are not well understood. We use neural networks (NNs), trained using archived output from eight chemical transport models (CTMs) that participated in the Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols and Transport Model Intercomparison Project (POLMIP), to quantify the factors responsible for differences in tropospheric OH and resulting CH4 lifetime (Tau CH4) between these models. Annual average Tau CH4, for loss by OH only, ranges from 8.0 to 11.6 years for the eight POLMIP CTMs. The factors driving these differences were quantified by inputting 3-D chemical fields from one CTM into the trained NN of another CTM. Across all CTMs, the largest mean differences in Tau CH4 (Delta Tau CH4) result from variations in chemical mechanisms (Delta Tau CH4 = 0.46 years), the photolysis frequency (J) of O3 yields O(D-1) (0.31 years), local O3 (0.30 years), and CO (0.23 years). The Delta Tau CH4 due to CTM differences in NO(x) (NO + NO2) is relatively low (0.17 years), although large regional variation in OH between the CTMs is attributed to NO(x). Differences in isoprene and J(NO2) have negligible overall effect on globally averaged tropospheric OH, although the extent of OH variations due to each factor depends on the model being examined. This study demonstrates that NNs can serve as a useful tool for quantifying why tropospheric OH varies between global models, provided that essential chemical fields are archived.
Bibliografie:	GSFC GSFC-E-DAA-TN46126 Report Number: GSFC-E-DAA-TN46126 ISSN: 2169-897X Goddard Space Flight Center E-ISSN: 2169-8996 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23
ISSN:	2169-897X 2169-8996
DOI:	10.1002/2016jd026239