TOGA (Trace Organic Gas Analyzer) Eric Apel, Alan Hills, Rebecca Hornbrook (ACOM/NCAR) with frequent participation from the UCI Blake group 2 min continuous analysis of >50 VOCs wide dynamic range, with detection limits at low pptv to sub-pptv range samples processed in flight using fast online GC/MS Post-processing of full data files takes ~ 2-3 days. VOC tracers from several sources/types: Biogenic VOCs and oxidation products Anthropogenic VOCs Oil and Gas Tracers Long-lived Halogenated VOCs Short-lived Halogenated VOCs OVOCs, including HCHO DMS Alkyl Nitrates Biomass burning tracers (HCN, CH3CN) TOGA is the trace organic gas analyzer, which is a fast GC-MS that does continuous simultaneous measurements of 50 + VOCs. It has a wide dynamic range with low ppt to sub-ppt detection limits. Samples are quick-processed in flight, and full post-processing takes about 2-3 days. VOCs provide tracers for several different sources, including biogenic VOCs, industrial and urban, O&G, oxidation products, including formaldehyde, DMS, alkyl nitrates and biomass burning. Installed on the G-V NCAR/ACOM TOGA group ATom Science Team Meeting

Long vs. short lived compounds Specific chemical compounds and groups of compounds are useful for isolating and understanding different physical and chemical processes Long vs. short lived compounds Compounds specific to different sources: emissions/ratios Some chemical compounds or groups of compounds are useful for understanding different physical or chemical processes, such as comparing long and short-lived compounds, looking at emission ratios to identify different sources, comparing parent and oxidation products, and contrasting soluble and insoluble compounds. Compound oxidation products Soluble and insoluble compounds

…but we need to know up front! TOGA Measured Compounds NMHCs: 1-butene/isobutene propane isobutane n-butane isopentane n-pentane 2-methylpentane 3-methylpentane n-hexane n-heptane benzene toluene ethylbenzene/p-/m-xylene o-xylene 1,2,3-trimethylbenzene 1,2,4-trimethylbenzene Alkyl Nitrates: methyl nitrate ethyl nitrate isopropyl nitrate butyl nitrates LOD; pptv 1 10 0.5 3 0.3 0.2 5 OVOCs: formaldehyde (HCHO) acetaldehyde (CH3CHO) propanal butanal acetone (CH3COCH3) MEK (butanone) methanol (CH3OH) ethanol (C2H5OH) 2-propanol acrolein (CH2CHCHO) MTBE (methyl tert-butyl ether) Biogenic VOCs: isoprene MBO (2-methyl-3-buten-2-ol) MVK methacrolein 3-methylfuran a-pinene b-pinene camphene limonene/3-carene 20 Halogenated VOCs: CFC-11 (CCl3F) CFC-113 (CCl2FCClF2) CH3Cl (methyl chloride) CH2Cl2 (dichloromethane) CHCl3 (chloroform) CCl4 (tetrachloromethane) C2Cl4 (tetrachloroethene) C6H5Cl (chlorobenzene) CH3Br (methyl bromide) CH2Br2 (dibromomethane) CHBr3 (bromoform) CH3I (methyl iodide) CH2I2 (diiodomethane) C2H5I (ethyl iodide) CH2ICl (chloroiodomethane) CHBrCl2 (bromodichloromethane) CHBr2Cl (dibromochloromethane) Others: DMS (dimethyl sulfide) HCN (hydrogen cyanide) Acetonitrile (CH3CN) 0.1 0.03 0.05 0.07 This is a list of all the compounds that we are currently able to quantify with TOGA, and the actualy targetted list for a given project can be tailored to best suit the experiment. The catch is that we need to plan the targetted list prior to the project, so if there are specific compounds that you’d like to see, please let us know well before the first deployment. Targeted VOCs can be modified and tailored to best suit objectives of experiment. …but we need to know up front! NCAR/ACOM TOGA group ATom Science Team Meeting

TOGA Species Measured and Lifetimes Reactivity with OH 105 OH (low), 107 OH (high), 210K, 310K TOGA species Hours Halocarbons Sulfur Containing Nitriles Oxygenates This is just another way of looking at the TOGA species, by OH reactivity lifetime. We measure compounds that range in lifetime from minutes to several months or even years. Biogenics Aromatics Alkenes Alkanes NCAR/ACOM TOGA group ATom Science Team Meeting

Aqueous phase interactions Solubilities Aqueous phase interactions We are also considering compounds with different solubilities. For the most part, the hydrocarbons are effectively insoluble, but some nitriles and OVOCs have solubilities that are relevant to atmospheric processes. NCAR/ACOM TOGA group ATom Science Team Meeting

CAM-chem – predicts CO plume Observations of tracers for air mass characterization during CONTRAST CAM-chem – predicts CO plume TOGA BB tracers: HCN, acetone, acetonitrile (lifetimes > 1 week) This is an example of how TOGA compounds were used to characterize an air mass during CONTRAST. In the chemical forecast, CAM-chem was predicting a CO plume just north of Guam. When we intersected the region, we saw our BB tracers all responding, like acetone, HCN and acetonitrile. Other TOGA tracers with shorter lifetimes were helpful to constrain the age of the BB emissions. Additional TOGA tracers with different lifetimes constrain age of air mass. NCAR/ACOM TOGA group ATom Science Team Meeting

Observations of North-South VOC gradients during CONTRAST (RF14) Flight to Australia Clear evidence of convective influence near New Guinea Benzene Extremely clean air near Australia Benzene During the CONTRAST project, we flew from Guam down to 20°S between 12 and 15 km. These plots show the TOGA benzene observations from this time period. And you can see that while we were near New Guinea there were some higher concentrations due to convection, but further south, we encountered very low concentrations. NCAR/ACOM TOGA group ATom Science Team Meeting

Observations of North-South VOC gradients during CONTRAST (RF14) TOGA benzene toluene acetaldehyde CAM-chem captures the benzene spatial distribution well – note the low values in SH NCAR/ACOM TOGA group ATom Science Team Meeting

TOGA Curtain Plots - CONTRAST TOGA has the time resolution to do meaningful vertical profiles. We hope to use these data to understand the global budgets of a lot of the species we measure, including longer-lived species like acetone and shorter lived species like bromoform. NCAR/ACOM TOGA group ATom Science Team Meeting

TOGA Curtain Plots - CONTRAST Main point for showing each of these compounds – tetrachloroethylene – anthropogenic tracer, HCN – BB tracer. NCAR/ACOM TOGA group ATom Science Team Meeting

TOGA Calibration Procedure Overflow inlet during zeros/cals In-flight Calibration system TOGA Inlet For our in flight calibration, we draw in and “clean” outside air through a (?) catalyst, and we add standards to generate a mixture with mid- to high-ppt concentrations of a number of VOCs, and then we overflow the inlet during this time. So this would be the only time that we send VOCs out through our inlet, which I know is a concern for any sampling inlets behind our inlet. So we can possibly do some sensitivity studies during a test flight, and plan coordinated calibrations during flights. NCAR/ACOM TOGA group ATom Science Team Meeting

Instrument status: Good TOGA Instrument Status, Logistics and Payload Concerns Instrument status: Good Data: Normally report 10 – 15 compounds in flight near real time: e.g. HCHO Acetone HCN Acetaldehyde Methanol CH3CN Butane DMS EtONO2 Benzene C2Cl4 i-PrONO2 Toluene CHCl3 Logistics: TOGA LN2 lasts ~ 10 hours , request possibility for in-flight LN2 addition NCAR/ACOM TOGA group ATom Science Team Meeting

Reminder: request specific compounds for TOGA to quantify AND, for the 24-h data deadline, we can provide a subset of high interest VOCs. NCAR/ACOM TOGA group ATom Science Team Meeting

TOGA Calibration and Standards TOGA – Calibrations – in-house – NIST – NOAA standards Compares well with established measurements – even at low mixing ratios NMHC examples (CONTRAST comparison with AWAS – Atlas) NCAR/ACOM TOGA group ATom Science Team Meeting

TOGA Calibration and Standards Halogenated species examples NCAR/ACOM TOGA group ATom Science Team Meeting

GC/MS - SIM NSF/NCAR Gulfstream V NSF/NCAR C130 TOGA Inlet TOGA on GV Acetaldehyde Isopentane Butane Methanol+Ethanol Pentane GC/MS - SIM Acetone Isobutane Dichloromethane Butanal, MEK CH2O Chloroform Benzene Toluene Ethylbenzene+Xylenes