# Direct high-altitude observations of 2-methyltetrols in the gas- and particle phase in air masses from Amazonia

## TL;DR

This study directly observed 2-methyltetrols in air masses from Amazonia at a high-altitude station in the Bolivian Andes, investigating their sources and transport.

## Contribution

The study provides direct high-altitude observations of 2-methyltetrols and their behavior in Amazonian air masses.

## Key findings

- 2-methyltetrol signals were dominant in a factor linked to Amazon emissions.
- 2-methyltetrol is likely taken up by hydrometeors or formed in convective clouds and transported to high altitudes.
- At high altitudes, 2-methyltetrol partially evaporates from the particle phase.

## Abstract

We present direct observations of 2-methyltetrol (C5H12O4) in the gas- and particle phase from the deployment of a Filter Inlet for Gases and Aerosols coupled to a Time-of-Flight Chemical Ionization Mass Spectrometer (FIGAERO-CIMS) during the Southern Hemisphere High Altitude Experiment on Particle Nucleation and Growth (SALTENA), which took place between December 2017 and June 2018 at the high-altitude Global Atmosphere Watch station Chacaltaya (CHC) located at 5240 m a s l in the Bolivian Andes. 2-Methyltetrol signals were dominant in a factor resulting from Positive Matrix Factorization (PMF) identified as influenced by Amazon emissions. We combine these observations with investigations of isoprene oxidation chemistry and uptake in an isolated deep convective cloud in the Amazon using a photochemical box model with coupled cloud microphysics and show that, likely, 2-methyltetrol is taken up by hydrometeors or formed in situ in the convective cloud, and then transported in the particle phase in the cold environment of the Amazon outflow and to the station, where it partially evaporates.

We present direct observations of 2-methyltetrol in the gas- and particle phase from the high-altitude measurement station Chacaltaya in the Bolivian Andes and investigate its sources and transport in air masses from Amazonia.