Between 1 September and 4 October 2014, a combined airborne and ground-based measurement campaign was conducted to study tropical deep convective clouds over the Brazilian Amazon rain forest. The new German research aircraft, High Altitude and Long Range Research Aircraft (HALO), a modified Gulfstream G550, and extensive ground-based instrumentation were deployed in and near Manaus (State of Amazonas). The campaign was part of the German–Brazilian Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (Global Precipitation Measurement) (ACRIDICON– CHUVA) venture to quantify aerosol–cloud–precipitation interactions and their thermodynamic, dynamic, and radiative effects by in situ and remote sensing measurements over Amazonia. The ACRIDICON–CHUVA field observations were carried out in cooperation with the second intensive operating period of Green Ocean Amazon 2014/15 (GoAmazon2014/5). In this paper we focus on the airborne data measured on HALO, which was equipped with about 30 in situ and remote sensing instruments for meteorological, trace gas, aerosol, cloud, precipitation, and spectral solar radiation measurements. Fourteen research flights with a total duration of 96 flight hours were performed. Five scientific topics were pursued: 1) cloud vertical evolution and life cycle (cloud profiling), 2) cloud processing of aerosol particles and trace gases (inflow and outflow), 3) satellite and radar validation (cloud products), 4) vertical transport and mixing (tracer experiment), and 5) cloud formation over forested/deforested areas. Data were collected in near-pristine atmospheric conditions and in environments polluted by biomass burning and urban emissions. The paper presents a general introduction of the ACRIDICON– CHUVA campaign (motivation and addressed research topics) and of HALO with its extensive instrument package, as well as a presentation of a few selected measurement results acquired during the flights for some selected scientific topics.

Abstract. The first tropospheric and stratospheric (4 to 33 km) BrO profile is presented for the inner tropics derived from balloon-borne DOAS (Differential Optical Absorption Spectroscopy) measurements. In combination with photochemical modelling, total stratospheric inorganic bromine (Br y ) is deduced to be (21.5±2.5) ppt in 4.5-year-old air, probed in 2005. We derive a total contribution of (5.2±2.5) ppt from brominated very short-lived substances and inorganic product gases to stratospheric Br y . Tropospheric BrO was found to be <1 ppt. Our results are compared to two 3-D CTM SLIMCAT model runs, which differ in the lifetime of the bromine source gases, affecting the vertical distribution of Br y in the lower stratosphere. Bromine source gas measurements performed 10 days earlier (Laube et al., 2008), indicate a lower Br y of (17.5±0.4) ppt. Potential reasons for this discrepancy are discussed.

[1] Vertical profiles of stratospheric bromine monoxide (BrO) in the 15-30 km range are retrieved from SCIAMACHY limb scatter data over the globe. First validation comparisons with the balloon-borne SAOZ-BrO and LPMA/DOAS instruments indicate retrieval biases of $20% or less. Propagated spectral fitting uncertainties lead to a precision approaching $25% on a 2 km grid at 25 km. This worsens at higher altitudes because of reduced signal and at lower altitudes because of the reduced penetrability of the atmosphere. In terms of volume mixing ratio (VMR), the single profile precision increases from $4 pptv at 17 km to $8 pptv at 27 km. Repeatability, an alternative indicator of precision, is 2-3 pptv for SCIAMACHY retrievals and independent of altitude. The BrO stratospheric number density peak generally lies 5 ± 2 km above the tropopause. In the tropics, the stratospheric BrO VMR generally increases with increasing altitude. The observed stratospheric BrO global distribution is generally consistent with previous balloon measurements but does not agree well with results of a model that uses Br y inferred only from the observed breakdown of long-lived bromoalkanes (i.e., methyl bromide and halons). We find best agreement with the observed vertical and latitudinal distribution of BrO for model results that include an 8.4 ± 2 pptv contribution to stratospheric Br y , most of which is expected from the breakdown of VSL (very short lived) bromocarbons, in addition to the $16 pptv contribution from longer-lived sources. This suggests that stratospheric Br y exceeds 20 pptv. Profiles of Br y profiles derived from the balloon measurements of BrO also suggest Br y is in excess of 20 pptv, but the uncertainty and variability of these results do not allow us to definitively rule out this concentration. We find typical BrO VMRs of $4 pptv at 15 km in the tropical tropopause layer, suggesting that a significant portion of the bromine from VSL bromoalkane sources may be carried across the tropopause in the form of inorganic decomposition products. We discuss a variety of VSL bromocarbons species that may be contributing to the elevated concentrations of stratospheric BrO.

Abstract. Emissions of halogenated very short-lived substances (VSLS) are poorly constrained. However, their inclusion in global models is required to simulate a realistic inorganic bromine (Br y ) loading in both the troposphere, where bromine chemistry perturbs global oxidising capacity, and in the stratosphere, where it is a major sink for ozone (O 3 ). We have performed simulations using a 3-D chemical transport model (CTM) including three top-down and a single bottom-up derived emission inventory of the major brominated VSLS bromoform (CHBr 3 ) and dibromomethane (CH 2 Br 2 ). We perform the first concerted evaluation of these inventories, comparing both the magnitude and spatial distribution of emissions. For a quantitative evaluation of each inventory, model output is compared with independent long-term observations at National Oceanic and Atmospheric Administration (NOAA) ground-based stations and with aircraft observations made during the NSF (National Science Foundation) HIAPER Pole-to-Pole Observations (HIPPO) project. For CHBr 3 , the mean absolute deviation between model and surface observation ranges from 0.22 (38 %) to 0.78 (115 %) parts per trillion (ppt) in the tropics, depending on emission inventory. For CH 2 Br 2 , the range is 0.17 (24 %) to 1.25 (167 %) ppt. We also use aircraft observations made during the 2011 Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere (SHIVA) campaign, in the tropical western Pacific. Here, the performance of the various inventories also varies significantly, but overall the CTM is able to reproduce observed CHBr 3 well in the free troposphere using an inventory based on observed sea-to-air fluxes. Finally, we identify the range of uncertainty associated with these VSLS emission inventories on stratospheric bromine loading due to VSLS (Br VSLS y ). Our simulations show Br VSLS y ranges from ∼ 4.0 to 8.0 ppt depending on the inventory. We report an optimised estimate at the lower end of this range (∼ 4 ppt) based on combining the CHBr 3 and CH 2 Br 2 inventories which give best agreement with the compilation of observations in the tropics.

(SAOZ and DOAS). An exception is the in situ Triple profile, in which the balloon and satellite data mostly does not agree within the given errors. In general, the satellite measurements show systematically higher values below 25 km than the balloon data and a change in profile shape above about 25 km.