Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Abstract

Abstract. The Amazon rain forest is considered a very sensitive ecosystem that could be significantly affected by a changing climate. It is still one of the few places on Earth where the atmosphere in the continent approaches near-pristine conditions for some periods of the year. The Amazon Tall Tower Observatory (ATTO) has been built in central Amazonia to monitor the atmospheric and forest ecosystem conditions. The atmospheric conditions at the ATTO site oscillate between biogenic and biomass burning (BB) dominated states. By using a comprehensive ground-based aerosol measurement setup, we studied the physical and chemical properties of aerosol particles at the ATTO site. This parameterization of å abs as a function of the BC to OA mass ratio was investigated and was found applicable to tropical forest emissions but further investigation is required, especially by segregating fuel types. Additionally, important enhancements of the BC mass absorption cross-section (α abs ) were found over the measurement period. This enhancement could be linked to heavy coating of the BC aerosol particles. In the future, the BC mixing state should be systematically investigated by using different instrumental approaches.

Long-term observations of cloud condensation nuclei over the Amazon rain forest – Part 2: Variability and characteristics of biomass burning, long-range transport, and pristine rain forest aerosols

“…These quickly and substantially changing aerosol regimes will presumably also impact the cloud conditions during the dry season. (iii) Finally, the Amazonian aerosol and CCN population can be substantially perturbed by emissions from sources (e.g., volcanoes in eastern Congo) that are remarkably far away from the ATTO site (∼ 10 000 km) (Saturno et al, 2017b). This emphasizes very clearly that intercontinental influences have to be considered carefully in the analysis of the Amazonian atmospheric composition.…”

“…The MPOL case study focuses on a period when African volcanogenic aerosols were advected to ATTO -an event that has been well documented in Saturno et al (2017b). We selected this episode since the microphysical properties of the volcanogenic aerosol are characteristic enough to discriminate them from the local/regional smoke emissions.…”

“…The 7-day MPOL period in September 2014 shows an exceptionally low OA / SO 2− 4 mass ratio (Table 3). Saturno et al (2017b) recently showed that the high sulfate concentrations can be explained by the long-range transport of volcanogenic aerosols from Africa (i.e., from the Nyiragongo and Nyamuragira volcanoes in eastern Congo) into the Amazon (compare also Fioletov et al, 2016). While the volcanogenic aerosol shows characteristic properties that allow this LRT component to be distinguished from the local/regional BB aerosol, African BB aerosols can be transported similarly; however, an experimental discrimination of African vs. Amazonian BB aerosol is difficult (see Saturno et al, 2017a).…”

“…(a) Incoming shortwave radiation, SW in ; precipitation rates from TRMM satellite mission, P TRMM ; and in situ measurements at the ATTO site, P ATTO . MPOL since BB-related sulfate contents are typically below 6-7 % (e.g., compare BB case in Table 3 as well as Fuzzi et al, 2007;Gunthe et al, 2009;Saturno et al, 2017b). Figure 6g and h summarize the N CN (D), N CCN (S,D), and κ(S, D a ) size distributions during MPOL, separately for the biomass burning pulses (MPOL-BB with OA / SO 2− 4 ≈ 4) and LRT influence (MPOL-LRT with lower OA / SO 2− 4 ≈ 3).…”

Supplementary material to "Land cover and its transformation in the backward trajectory footprint region of the Amazon Tall Tower Observatory"

“…Settings for BT calculations at both sites were identical (GDAS1, start height 1000 m AGL, trajectories started every 1 h). In this context, compare alsoSaturno et al (2017).…”