Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: airborne measurements

Martínez, Mònica; Harder, Hartwig; Kubistin, Dagmar; Rudolf, M.; Bozem, Heiko; Eerdekens, G.; Fischer, H.; Klüpfel, T.; Gurk, C.; Königstedt, R.; Parchatka, Uwe; Schiller, C. L.; Stickler, Alexander; Williams, Jonathan; Lelieveld, J.

doi:10.5194/acp-10-3759-2010

Cited by 142 publications

(165 citation statements)

References 43 publications

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“…Instead, the observed IO U-shape indicates a diurnal behaviour that is not directly related to vertical transport. A possible explanation for the IO minimum around noon is the reaction of IO + HO 2 , an important reaction pathway at low IO concentrations, leading to the formation of a temporary iodine reservoir, HOI, at midday when HO 2 levels peak in the FT (Martinez et al, 2010). Note also that the IO diurnal behaviour can be different in the MBL and FT as the nature of the reactive iodine precursors is most likely also different.…”

Section: Diurnal Evolutionmentioning

confidence: 99%

Iodine monoxide in the north subtropical free troposphere

et al. 2012

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Abstract. Iodine monoxide (IO) differential slant column densities (DSCD) have been retrieved from a new multi-axis differential optical absorption spectroscopy (MAX-DOAS) instrument deployed at the Izaña subtropical observatory as part of the Network for the Detection of Atmospheric Composition Change (NDACC) programme. The station is located at 2370 m a.s.l., well above the trade wind inversion that limits the top of the marine boundary layer, and hence is representative of the free troposphere. We report daily observations from May to August 2010 at different viewing angles. During this period, the spectral signature of IO was unequivocally detected on every day of measurement. A mean IO DSCD of 1.52×10 13 molecules cm −2 was observed at the 5 • instrument elevation angle (IEA) on clear days using a single zenith reference for the reported period, with a day-to-day variability of 33 % at one standard deviation. Based on the simulation of the DSCDs using radiative transfer calculations with five different hypothesized IO profiles, the IO mixing ratio is estimated to range between 0.2 and 0.4 pptv in the free troposphere. Episodes of Saharan dust outbreaks were also observed, with large increases in the DSCDs at higher IEA, suggesting an enhancement of IO inside the dust cloud.

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Section: Diurnal Evolutionmentioning

confidence: 99%

Iodine monoxide in the north subtropical free troposphere

et al. 2012

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“…HO 2 was measured indirectly after conversion to OH by addition of NO. The instrumental setup has already been used in a similar configuration during the GABRIEL campaign and is described in detail in Martinez et al (2010). The precision of the LIF instrument during HOOVER was determined to be 7 % for OH and 1 % for HO 2 with a detection limit of 0.02 pmol mol −1 for OH and 0.08 pmol mol −1 for HO 2 .…”

Section: Other Speciesmentioning

confidence: 99%

Distribution of hydrogen peroxide and formaldehyde over Central Europe during the HOOVER project

et al. 2011

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Abstract. In this study we report measurements of hydrogen peroxide (H 2 O 2 ), methyl hydroperoxide* (MHP* as a proxy of MHP based on an unspecific measurement of total organic peroxides) and formaldehyde (HCHO) from the HO x OVer EuRope (HOOVER) project (HO x = OH+HO 2 ). HOOVER included two airborne field campaigns, in October 2006 and July 2007. Measurement flights were conducted from the base of operation Hohn (Germany, 54 • N, 9 • E) towards the Mediterranean and to the subpolar regions over Norway. We find negative concentration gradients with increasing latitude throughout the troposphere for H 2 O 2 and CH 3 OOH * . In contrast, observed HCHO is almost homogeneously distributed over central and northern Europe and is elevated over the Mediterranean. In general, the measured gradients tend to be steepest entering the Mediterranean region, where we also find the highest abundances of the 3 species. Mixing ratios of these tracers generally decrease with altitude. H 2 O 2 and CH 3 OOH * show maxima above the boundary layer at 2-5 km, being more distinct over southern than over northern Europe.We also present a comparison of our data with simulations by two global 3-D-models, MATCH-MPIC and EMAC, and with the box model CAABA. The models realistically represent altitude and latitude gradients for both HCHO and hydroperoxides (ROOH). In contrast, the models have problems reproducing the absolute mixing ratios, in particular of H 2 O 2 . Large uncertainties about retention coefficients and Correspondence to: H. Fischer (horst.fischer@mpic.de) cloud microphysical parameters suggest that cloud scavenging might be a large source of error for the simulation of H 2 O 2 . A sensitivity study with EMAC shows a strong influence of cloud and precipitation scavenging on the budget of H 2 O 2 as simulations improve significantly with this effect switched off.

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“…Details of the instrument are available elsewhere (Martinez et al, 2010). The accuracy of the OH and HO 2 measurement was ± 18 % and the precision was 0.034 pptv for OH and 0.23 pptv for HO 2 .…”

Section: Oh and Ho 2 Measurementsmentioning

confidence: 99%

Constraints on instantaneous ozone production rates and regimes during DOMINO derived using in-situ OH reactivity measurements

et al. 2012

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Abstract. In this study air masses are characterized in terms of their total OH reactivity which is a robust measure of the "reactive air pollutant loading". The measurements were performed during the DOMINO campaign (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) held from 21/11/2008 to 08/12/2008 at the Atmospheric Sounding Station -El Arenosillo (37.1 • N-6.7 • W, 40 m a.s.l.). The site was frequently impacted by marine air masses (arriving at the site from the southerly sector) and air masses from the cities of Huelva (located NW of the site), Seville and Madrid (located NNE of the site). OH reactivity values showed strong wind sector dependence. North eastern "continental" air masses were characterized by the highest OH reactivities (average: 31.4 ± 4.5 s −1 ; range of average diel values: 21.3-40.5 s −1 ), followed by north western "industrial" air masses (average: 13.8 ± 4.4 s −1 ; range of average diel values: 7-23.4 s −1 ) and marine air masses (average: 6.3 ± 6.6 s −1 ; range of average diel values: below detection limit −21.7 s −1 ), respectively. The average OH reactivity for the entire campaign period was ∼18 s −1 and no pronounced variation was discernible in the diel profiles with the exception of relatively high values from 09:00 to 11:00 UTC on occasions when air masses arrived from the north western and southern wind sectors. The measured OH reactivity was used to constrain both diel instantaneous ozone production potential rates and regimes. Gross ozone production rates at the site were generally limited by the availability of NO x with peak values of around 20 ppbV O 3 h −1 . Using the OH reactivity based approach, derived ozone production rates indicate that if NO x would no longer be the limiting factor in air masses arriving from the continental north eastern sector, peak ozone production rates could double. We suggest that the new combined approach of in-situ fast measurements of OH reactivity, nitrogen oxides and peroxy radicals for constraining instantaneous ozone production rates, could significantly improve analyses of upwind point sources and their impact on regional ozone levels.

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Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: airborne measurements

Cited by 142 publications

References 43 publications

Iodine monoxide in the north subtropical free troposphere

Iodine monoxide in the north subtropical free troposphere

Distribution of hydrogen peroxide and formaldehyde over Central Europe during the HOOVER project

Constraints on instantaneous ozone production rates and regimes during DOMINO derived using in-situ OH reactivity measurements

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