09 Mar 2022
09 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Significant continental source of ice-nucleating particles at the tip of Chile’s southernmost Patagonia region

Xianda Gong1, Martin Radenz1, Heike Wex1, Patric Seifert1, Farnoush Ataei1, Silvia Henning1, Holger Baars1, Boris Barja2, Albert Ansmann1, and Frank Stratmann1 Xianda Gong et al.
  • 1Leibniz Institute for Tropospheric Research, Leipzig, Germany
  • 2Laboratorio de Investigaciones Atmosféricas, Universidad de Magallanes (UMAG), Punta Arenas, Chile

Abstract. The sources and abundance of ice-nucleating particles (INPs) that initiate cloud ice formation remain understudied, especially in the Southern Hemisphere. In this study, we present INP measurement taken close to Punta Arenas, Chile, at the southernmost tip of South America from May 2019 to March 2020, during the Dynamics, Aerosol, Clouds, and Precipitation in the Pristine Environment of the Southern Ocean (DACAPO-PESO) campaign.

The highest ice nucleation temperature was observed at -3 °C, and from this temperature down to ~ -10 °C, a sharp increase of INP number concentration (NINP) was observed. Roughly 90 % and 80 % of INPs are proteinaceous-based biogenic particles at > -10 and -15 °C, respectively. NINP at Punta Arenas is much higher than that in the Southern Ocean, but comparable with agricultural area in Argentina and forestry environment in the US. Ice active surface site density (ns) is much higher than that for marine aerosol in the Southern Ocean, but comparable to English fertile soil dust. Parameterization based on particle number concentration in the size range larger than 500 nm (N>500nm) from the global average (DeMott et al., 2010) overestimate the measured INP, but the parameterization representing biological particles from a forestry environment (Tobo et al., 2013) yields NINP comparable to this study.

No clear seasonal variation of NINP was observed. High precipitation is one of the most important meteorological parameters to enhance the NINP both in cold and warm seasons. A comparison of data from in-situ and lidar measurements showed good agreement for concentrations of large aerosol particles (> 500 nm) when assuming continental conditions for retrieval of the lidar data, suggesting that these particles were well mixed within the planetary boundary layer. This corroborates a continental origin of these particles, consistent with the results from our INP source analysis. Overall, we suggest that high NINP of biogenic INPs originated from terrestrial sources and were added to the marine air masses during the overflow of a maximum of roughly 150 km of land before arriving at the measurement station.

Xianda Gong et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-71', Anonymous Referee #1, 24 Mar 2022
  • RC2: 'Comment on acp-2022-71', Anonymous Referee #2, 21 Apr 2022

Xianda Gong et al.

Xianda Gong et al.


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Short summary
The sources of the ice-nucleating particle (INP) are poorly understood in the Southern Hemisphere (SH). We studied INP in the boundary layer in the southern Patagonia region. No seasonal cycle of INP concentrations was observed. The majority of INPs are biogenic particles, likely from local continental sources. INP concentrations are higher when strong precipitation occurs. While previous studies focused on marine INP sources in the SH, we point out the importance of continental sources of INP.