TY  - JOUR
A1  - Niedermeier, Dennis
A1  - Hartmann, Susan
A1  - Clauss, Tina
A1  - Wex, Heike
A1  - Kiselev, Alexei
A1  - Sullivan, Ryan C.
A1  - DeMott, Paul J.
A1  - Petters, Markus D.
A1  - Reitz, Paul
A1  - Schneider, Johannes
A1  - Mikhailov, Eugene
A1  - Sierau, Berko
A1  - Stetzer, Olaf
A1  - Reimann, Bernd
A1  - Bundke, Ulrich
A1  - Shaw, Raymond A.
A1  - Buchholz, Angela
A1  - Mentel, Thomas F.
A1  - Stratmann, Frank
T1  - Experimental study of the role of physicochemical surface processing on the IN ability of mineral dust particles
T2  - Atmospheric chemistry and physics / Discussions, 11.2011, S. 18557-18588
N2  - During the measurement campaign FROST 2 (FReezing Of duST 2), the Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate the influences of various surface modifications on the immersion freezing behavior of Arizona Test Dust (ATD) particles. The dust particles were exposed to sulfuric acid vapor, to water vapor with and without the addition of ammonia gas, and heat using a thermodenuder operating at 250 °C. Size selected, quasi monodisperse particles with a mobility diameter of 300 nm were fed into LACIS and droplets grew on these particles such that each droplet contained a single particle. Temperature dependent frozen fractions of these droplets were determined in a temperature range between −40 °C ≤ T ≤ −28 °C. The pure ATD particles nucleated ice over a~broad temperature range with their freezing behavior being separated into two freezing branches characterized through different slopes in the frozen fraction vs. temperature curves. Coating the ATD particles with sulfuric acid resulted in the particles' IN potential significantly decreasing in the first freezing branch (T > −35 °C) and a slight increase in the second branch (T≤ −35 °C). The addition of water vapor after the sulfuric acid coating caused the disappearance of the first freezing branch and a strong reduction of the IN ability in the second freezing branch. The presence of ammonia gas during water vapor exposure had a negligible effect on the particles' IN ability compared to the effect of water vapor. Heating in the thermodenuder led to a decreased IN ability of the sulfuric acid coated particles for both branches but the additional heat did not or only slightly change the IN ability of the pure ATD and the water vapor exposed sulfuric acid coated particles. In other words, the combination of both sulfuric acid and water vapor being present is a main cause for the ice active surface features of the ATD particles being destroyed. A possible explanation could be the chemical transformation of ice active metal silicates to metal sulfates. From an atmospheric point of view, and here specifically the influences of atmospheric aging on the IN ability of dust particles, the strongly enhanced reaction between sulfuric acid and dust in the presence of water vapor, and the resulting significant reductions in IN potential, are certainly very interesting.
Y1  - 2011
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/26781
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-267812
SN  - 1680-7375
SN  - 1680-7367
N1  - © Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License.
VL  - 11
SP  - 18557
EP  - 18588
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -