TY  - JOUR
A1  - Pöhlker, Mira L.
A1  - Pöhlker, Christopher
A1  - Klimach, Thomas
A1  - Hrabe de Angelis, Isabella
A1  - Barbosa, Henrique M. J.
A1  - Brito, Joel
A1  - Carbone, Samara
A1  - Cheng, Yafang
A1  - Chi, Xuguang
A1  - Ditas, Florian
A1  - Ditz, Reiner
A1  - Gunthe, Sachin S.
A1  - Kesselmeier, Jürgen
A1  - Könemann, Tobias
A1  - Lavrič, Jost-Valentin
A1  - Martin, Scot Turnbull
A1  - Moran-Zuloaga, Daniel
A1  - Rose, Diana
A1  - Saturno, Jorge
A1  - Su, Hang
A1  - Thalman, Ryan
A1  - Walter, David
A1  - Wang, Jian
A1  - Wolff, Stefan
A1  - Artaxo, Paulo
A1  - Andreae, Meinrat O.
A1  - Pöschl, Ulrich
T1  - Long-term observations of atmospheric aerosol, cloud condensation nuclei concentration and hygroscopicity in the Amazon rain forest – Part 1: Size-resolved characterization and new model parameterizations for CCN prediction
T2  - Atmospheric chemistry and physics. Discussions
N2  - Size-resolved long-term measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations as well as hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a one-year period and full seasonal cycle (March 2014 - February 2015). The presented measurements provide a climatology of CCN properties for a characteristic central Amazonian rain forest site.
The CCN measurements were continuously cycled through 10 levels of supersaturation (S = 0.11 to 1.10 %) and span the aerosol particle size range from 20 to 245 nm. The observed mean critical diameters of CCN activation range from 43 nm at S = 1.10 % to 172 nm at S = 0.11 %. The particle hygroscopicity exhibits a pronounced size dependence with lower values for the Aitken mode (κAit = 0.14 ± 0.03), elevated values for the accumulation mode (κAcc = 0.22 ± 0.05), and an overall mean value of κmean = 0.17 ± 0.06, consistent with high fractions of organic aerosol.
The hygroscopicity parameter κ exhibits remarkably little temporal variability: no pronounced diurnal cycles, weak seasonal trends, and few short-term variations during long-range transport events. In contrast, the CCN number concentrations exhibit a pronounced seasonal cycle, tracking the pollution-related seasonality in total aerosol concentration. We find that the variability in the CCN concentrations in the central Amazon is mostly driven by aerosol particle number concentration and size distribution, while variations in aerosol hygroscopicity and chemical composition matter only during a few episodes.
For modelling purposes, we compare different approaches of predicting CCN number concentration and present a novel parameterization, which allows accurate CCN predictions based on a small set of input data.
Y1  - 2016
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/42238
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-422388
SN  - 1680-7375
SN  - 1680-7367
N1  - © Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License.
VL  - 16
IS  - 519
SP  - 1
EP  - 54
PB  - European Geosciences Union
CY  - Katlenburg-Lindau.
ER  -