An overview of the Amazonian Aerosol Characterization Experiment 2008 (AMAZE-08)

Abstract

The Amazon Basin provides an excellent environment for studying the sources, transformations, and properties of natural aerosol particles and the resulting links between biological processes and climate. With this framework in mind, the Amazonian Aerosol Characterization Experiment (AMAZE-08), carried out from 7 February to 14 March 2008 during the wet season in the central Amazon Basin, sought to understand the formation, transformations, and cloud-forming properties of fine- and coarse-mode biogenic aerosol particles, especially as related to their effects on cloud activation and regional climate. Special foci included (1) the production mechanisms of secondary organic components at a pristine continental site, including the factors regulating their temporal variability, and (2) predicting and understanding the cloud-forming properties of biogenic particles at such a site. In this overview paper, the field site and the instrumentation employed during the campaign are introduced. Observations and findings are reported, including the large-scale context for the campaign, especially as provided by satellite observations. New findings presented include: (i) a particle number-diameter distribution from 10 nm to 10 μm that is representative of the pristine tropical rain forest and recommended for model use; (ii) the absence of substantial quantities of primary biological particles in the submicron mode as evidenced by mass spectral characterization; (iii) the large-scale production of secondary organic material; (iv) insights into the chemical and physical properties of the particles as revealed by thermodenuder-induced changes in the particle number-diameter distributions and mass spectra; and (v) comparisons of ground-based predictions and satellite-based observations of hydrometeor phase in clouds. A main finding of AMAZE-08 is the dominance of secondary organic material as particle components. The results presented here provide mechanistic insight and quantitative parameters that can serve to increase the accuracy of models of the formation, transformations, and cloud-forming properties of biogenic natural aerosol particles, especially as related to their effects on cloud activation and regional climate

Organic Constituents on the Surfaces of Aerosol Particles from Southern Finland, Amazonia, and California Studied by Vibrational Sum Frequency Generation

“…To address these challenges and show one way of how they may be overcome, we summarize and compare our results from the application of coherent vibrational spectroscopy, specifically vibrational sum frequency generation (SFG), to the surfaces of aerosol particles collected in the central Amazon Basin, 9 chosen as an example of a tropical forest, in Southern Finland, 3 chosen as an example of the boreal forest, and in Blodgett Forest, California, 10 an anthropogenically influenced ponderosa pine forest ( Figure 1B). Tropical forest air is typically rich in isoprene, whereas air over the boreal and the pine forests is typically rich in α-pinene, and we expect the vibrational spectra obtained from the particles to be due to oxidation products of these compounds in the particle phase.…”

“…By working with the Harvard Environmental Chamber (HEC), 11 we compare the results from the natural samples with those obtained from synthetic model systems. We learn from our studies that in addition to its surface selectivity, SFG spectroscopy can provide a substantial sensitivity advantage over other nondestructive methods that can be performed under ambient temperature and pressure conditions, and that SFG is most informative when it is combined with the full range of aerosol particle and gas phase analytics that are typical of large-scale atmospheric chemistry field campaigns such as AMAZE-08, 9 HUMPPA-COPEC-2010, 3 or BEARPEX-2009. 12 II.…”

“…The tropical forest field site is located at tower TT34, 9 which is situated within a pristine terra firme rainforest in the Reserva Biologica do Cuieiras and managed by the Instituto Nacional de Pesquisas da Amazonia (INPA) and the Large-Scale BiosphereAtmosphere Experiment in Amazonia (LBA), 60 km NNW of downtown Manaus ( Figure 1B, right panel). The forest canopy height near the tower varies between 30 and 35 m; the sampling height on the tower is 38.75 m. Andreae et al 57 summarized meteorological and climatological information typical of the climatology at the reserve.…”

A permanent Raman lidar station in the Amazon: description, characterization, and first results

“…The first relatively long-term ground-based lidar observations in the central Amazon took place during the European Integrated Project on Aerosol, Cloud, Climate, Air Quality Interactions, (EUCAARI, Kulmala et al, 2011), and the Amazonian Aerosol Characterization Experiment (AMAZE-08, Martin et al, 2010). From 10 months of observations in 2008, analyzed 60 wet and 55 dry season days where meteorological and instrumental conditions were optimal.…”

Stereochemical transfer to atmospheric aerosol particles accompanying the oxidation of biogenic volatile organic compounds

“…Therefore, we expect stereochemical transfer to be active in the natural environment as well. As one example, we evaluated molecular chirality in atmospheric aerosol particles rich in secondary organic material that were collected under the pristine conditions of the central Amazon Basin [Pöschl et al, 2010] at tower TT34 during the wet season of February and March 2008 [Martin et al, 2010a]. Close to 90% of detected particles consist of secondary organic aerosol (SOA) droplets that were formed by atmospheric oxidation and gas-to-particle conversion of biogenic volatile organic compounds.…”