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

Abstract

Abstract. The Amazon rain forest experiences the combined pressures from human-made deforestation and progressing climate change, causing severe and potentially disruptive perturbations of the ecosystem's integrity and stability. To intensify research on critical aspects of Amazonian biosphere–atmosphere exchange, the Amazon Tall Tower Observatory (ATTO) has been established in the central Amazon Basin. Here we present a multi-year analysis of backward trajectories to derive an effective footprint region of the observatory, which spans large parts of the particularly vulnerable eastern basin. Further, we characterize geospatial properties of the footprint regions, such as climatic conditions, distribution of ecoregions, land cover categories, deforestation dynamics, agricultural expansion, fire regimes, infrastructural development, protected areas, and future deforestation scenarios. This study is meant to be a resource and reference work, helping to embed the ATTO observations into the larger context of human-caused transformations of Amazonia. We conclude that the chances to observe an unperturbed rain forest–atmosphere exchange at the ATTO site will likely decrease in the future, whereas the atmospheric signals from human-made and climate-change-related forest perturbations will increase in frequency and intensity.

Influx of African biomass burning aerosol during the Amazonian dry season through layered transatlantic transport of black carbon-rich smoke

“…Atlantic, and the Amazon Basin have found pollution layers in the free troposphere with similar characteristics (e.g., Andreae et al, 1988;Diab et al, 1996;Thompson et al, 1996;Bozem et al, 2014;Marenco et al, 2016). Recent studies in the central basin, at the Amazon Tall Tower Observatory (ATTO), and in northeastern edge of the Amazon discovered indications for a significant abundance of African smoke during the Amazonian dry season (Barkley et al, 2019;Pöhlker et al, 2019Pöhlker et al, , 2018Saturno et al, 2018b;135 Wang et al, 2016). However, robust quantitative data from observations and/or models (e.g., African BC and CCN fractions in the basin) have remained sparse.…”

“…The NOAA hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model (Stein et al, 2015) was used to obtain systematic and multiyear sets of backward trajectories (BTs) for the ATTO site as outlined in detail in Pöhlker et al (2019). The time series of cumulative fire intensity along the BTs was calculated based on (i) an ensemble of three-day HYSPLIT BTs, started every hour in the time frame between 01 January 2013 and 31 December 2018, at a starting height of 1000 m, and (ii) daily georeferenced 300 fire intensity maps (unit W m -2 ) from the Global Fire Assimilation System (GFAS).…”

“…The time series of cumulative fire intensity along the BTs was calculated based on (i) an ensemble of three-day HYSPLIT BTs, started every hour in the time frame between 01 January 2013 and 31 December 2018, at a starting height of 1000 m, and (ii) daily georeferenced 300 fire intensity maps (unit W m -2 ) from the Global Fire Assimilation System (GFAS). Details on the BT data set can be found in Pöhlker et al (2019). The GFAS fire intensity maps were obtained as NetCDF3 files with a spatial resolution of 0.1° latitude by 0.1° longitude (0.1° equal roughly 11 km).…”

“…The following GIS data sets were used in this study: (i) maps of global water bodies obtained from the European Space Agency (ESA) Olson et al (2001). For further details, we refer to Pöhlker et al (2019).…”

Understanding nighttime methane signals at the Amazon Tall Tower Observatory (ATTO)

“…Most of the data points in the ESE wind direction match the reference slope for biofuel burning, which is defined by Akagi et al (2011) as biomass used as a domestic or industrial energy source. Hence, biofuel burning is associated with human activity and according to the comprehensive study of Pöhlker et al (2019), in the ESE direction there is substantial fire activity, the 5 rainforest has suffered more fragmentation and degradation and there are more settlements. It is worth recalling that here we are focusing on nighttime data when stable atmospheric conditions prevail, therefore the BC associated with biofuel burning might come from nearby settlements.…”