Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

Borrmann, Stephan; Kunkel, Daniel; Weigel, Ralf; Minikin, Andreas; Deshler, Terry; Wilson, J. C.; Curtius, Joachim; Volk, C. M.; Homan, C. D.; Ulanovsky, A.; Ravegnani, F.; Viciani, Silvia; Shur, G. N.; Belyaev, G. V.; Law, Kathy S.; Cairo, F.

doi:10.5194/acp-10-5573-2010

Cited by 69 publications

(123 citation statements)

References 72 publications

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“…A comprehensive summary of ultrafine aerosol measurements in the TTL was provided by Borrmann et al (2010) and Weigel et al (2011), based mainly on aircraft campaigns with the M55 Geophysica and DLR Falcon. A key result of these papers is the maximum in particle concentration around 350 K potential temperature, near the main outflow region for deep tropical convection.…”

Section: A Waddicor Et Al: Aerosol In the Tropical Tropopause Layermentioning

confidence: 99%

Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

et al. 2012

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Abstract. We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvil of a deep tropical thunderstorm. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol with diameter greater than 10 nm were 25 000 cm −3 (STP). By calculating back-trajectories from the observations, and projecting onto infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of about 3 hours was derived for the Aitken aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO 2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes >10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

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Section: A Waddicor Et Al: Aerosol In the Tropical Tropopause Layermentioning

confidence: 99%

Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

et al. 2012

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“…Observational evidence suggests that the upper tropical troposphere is one of the most important source regions for the stratospheric particles in the Junge aerosol layer Thomason and Peter, 2006;Borrmann et al, 2010). However, an evaluation of the different mechanisms forming new particles by Lucas and Akimoto (2006) revealed that qualitatively, due to the large uncertainties of parameterizations, NPF was so far inadequately represented in global models.…”

Section: Introductionmentioning

confidence: 99%

In situ observations of new particle formation in the tropical upper troposphere: the role of clouds and the nucleation mechanism

Weigel

Borrmann²,

Kazil³

et al. 2011

Atmos. Chem. Phys.

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Abstract. New particle formation (NPF), which generates nucleation mode aerosol, was observed in the tropical Upper Troposphere (UT) and Tropical Tropopause Layer (TTL) by in situ airborne measurements over South America (JanuaryMarch 2005), Australia (November-December 2005), West Africa (August 2006) and Central America (2004. Particularly intense NPF was found at the bottom of the TTL. Measurements with a set of condensation particle counters (CPCs) with different d p50 (50 % lower size detection efficiency diameter or "cut-off diameter") were conducted on board the M-55 Geophysica in the altitude range of 12.0-20.5 km and on board the DLR Falcon-20 at up to 11.5 km altitude. On board the NASA WB-57F size distributions were measured over Central America in the 4 to 1000 nm diameter range with a system of nucleation mode aerosol specCorrespondence to: R. Weigel (weigelr@uni-mainz.de) trometers. Nucleation mode particle concentrations (N NM ) were derived from these measurements which allow for identifying many NPF events with N NM in the range of thousands of particles per cm 3 . Over Australia and West Africa, we identified NPF in the outflow of tropical convection, in particular of a Mesoscale Convective System (MCS). Newly formed particles with N NM > 1000 cm −3 were found to coexist with ice cloud particles (d p > 2 µm) as long as cloud particle concentrations remained below 2 cm −3 . The occurrence of NPF within the upper troposphere and the TTL was generally confined within 340 K to 380 K potential temperature, but NPF was of particular strength between 350 K and 370 K (i.e. ∼1-4 km below the cold point tropopause). Analyses of the aerosol volatility (at 250 • C) show that in the TTL on average 75-90 % of the particles were volatile, compared to typically only 50 % in the extra-tropical UT, indicative for the particles to mainly consist of H 2 SO 4 -H 2 O and possibly organic compounds. Along two flight segments over Central and South America (24 February 2005 and 7 August Published by Copernicus Publications on behalf of the European Geosciences Union. 2006, at 12.5 km altitude) in cloud free air, above thin cirrus, particularly high N NM were observed. Recent lifting had influenced the probed air masses, and N NM reached up to 16 000 particles cm −3 (ambient concentration). A sensitivity study using an aerosol model, which includes neutral and ion induced nucleation processes, simulates N NM in reasonable agreement with the in situ observations of clear-air NPF. Based on new, stringent multi-CPC criteria, our measurements corroborate the hypothesis that the tropical UT and the TTL are regions supplying freshly nucleated particles. Our findings narrow the altitude of the main source region to the bottom TTL, i.e. to the level of main tropical convection outflow, and, by means of measurements of carbon monoxide, they indicate the importance of anthropogenic emissions in NPF. After growth and/or coalescence the nucleation mode particles may act as cloud condensation nuclei in the tropical UT, or, upon ...

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“…An important source for stratospheric particles is the tropical tropopause region, where nucleation-mode particles have been observed. Additionally, new particle formation has also been observed in the free troposphere (Brock et al, 1995;Clarke et al, 1999;Borrmann et al, 2010;Weigel et al, 2011). Due to the volatility and the identification of sulfur in collected particles, it was concluded that binary nucleation contributes to (or dominates) the formation of these particles (Brock et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of the formation of sulfuric acid dimers in the binary (H2SO4–H2O) and ternary (H2SO4–H2O–NH3) system

Kürten¹,

Münch

Rondo

et al. 2015

Atmos. Chem. Phys.

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Abstract. Sulfuric acid is an important gas influencing atmospheric new particle formation (NPF). Both the binary (H 2 SO 4 -H 2 O) system and the ternary system involving ammonia (H 2 SO 4 -H 2 O-NH 3 ) may be important in the free troposphere. An essential step in the nucleation of aerosol particles from gas-phase precursors is the formation of a dimer, so an understanding of the thermodynamics of dimer formation over a wide range of atmospheric conditions is essential to describe NPF. We have used the CLOUD chamber to conduct nucleation experiments for these systems at temperatures from 208 to 248 K. Neutral monomer and dimer concentrations of sulfuric acid were measured using a chemical ionization mass spectrometer (CIMS). From these measurements, dimer evaporation rates in the binary system were derived for temperatures of 208 and 223 K. We compare these results to literature data from a previous study that was conducted at higher temperatures but is in good agreement with the present study. For the ternary system the formation of Published by Copernicus Publications on behalf of the European Geosciences Union. A. Kürten et al.: Thermodynamics of the formation of sulfuric acid dimersH 2 SO 4 q NH 3 is very likely an essential step in the formation of sulfuric acid dimers, which were measured at 210, 223, and 248 K. We estimate the thermodynamic properties (dH and dS) of the H 2 SO 4 q NH 3 cluster using a simple heuristic model and the measured data. Furthermore, we report the first measurements of large neutral sulfuric acid clusters containing as many as 10 sulfuric acid molecules for the binary system using chemical ionization-atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometry.

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Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

Cited by 69 publications

References 72 publications

Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

In situ observations of new particle formation in the tropical upper troposphere: the role of clouds and the nucleation mechanism

Thermodynamics of the formation of sulfuric acid dimers in the binary (H<sub>2</sub>SO<sub>4</sub>–H<sub>2</sub>O) and ternary (H<sub>2</sub>SO<sub>4</sub>–H<sub>2</sub>O–NH<sub>3</sub>) system

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Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

Cited by 69 publications

References 72 publications

Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

In situ observations of new particle formation in the tropical upper troposphere: the role of clouds and the nucleation mechanism

Thermodynamics of the formation of sulfuric acid dimers in the binary (H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;–H&lt;sub&gt;2&lt;/sub&gt;O) and ternary (H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;–H&lt;sub&gt;2&lt;/sub&gt;O–NH&lt;sub&gt;3&lt;/sub&gt;) system

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Thermodynamics of the formation of sulfuric acid dimers in the binary (H<sub>2</sub>SO<sub>4</sub>–H<sub>2</sub>O) and ternary (H<sub>2</sub>SO<sub>4</sub>–H<sub>2</sub>O–NH<sub>3</sub>) system