Role of aqueous aerosol in the build up of large upper tropospheric moisture Anatoli Bogdan Institute of Physical Chemistry, University of Innsbruck Austria and Department of Physics, University of Helsinki Finland
Contents Introduction - observational data of UT moisture - water activity criterion Approaches for explanation of large UT moisture - cubic ice hypothesis - organic coating around sulfuric acid aerosol - glassy organic (citric acid) aerosol - mixed-phase cirrus cloud particles
Observations of UT moisture
The warming is large at the upper troposphere in the tropics and the lower troposphere in the northern high latitude.
Water activity criterion
Maximum RH i of aqueous aerosol droplets which is allowed by a water activity criterion (WAC).
Equilibrium partial pressures of the components of ideal and non-ideal binary solution as a function of the mole fraction X A. When X A → 1, we have a dilute solution of B in A. In this region the Raoult’s law p A = X A p* A is applied for A. In the region where X A → 0, we have the Raoult’s law p B = X B p* B for B component.
, Water activity may be approximated as
Cubic ice hypothesis
Hexagonal ice
The arrangement of water molecules in hexagonal ice
Cubic ice Hexagonal ice lattice
Diffraction patterns from frozen emulsified droplets of 30 wt % HNO 3.
Ratio of vapor pressure of cubic and hexagonal ices
The hypotheses of organic coating around sulfuric acid aerosol
Organic coating of sulfuric acid aerosol
The hypotheses of concentrated glassy citric acid aerosol
Calorimetric thermograms of emulsified 17 wt% H 2 SO 4 and 17/3 wt% H 2 SO 4 /HNO 3.
Complete and truncated thermograms of 20wt% H 2 SO 4.
16 Cooling Droplets are on hydrophobic surface. 50 μm
17 Cooling
18 Cooling
19 Cooling
20 Cooling
21 Cooling
22 Cooling
23 Cooling
39 Warming
40 Warming
41 Warming
42 Warming
43 Warming
44 Warming
45 Warming
46 Warming
47 Warming
48 Warming
49 Warming
50 Warming
51 Warming
52 Warming
54 Warming
55 Warming
56 Warming
57 Warming
58 Warming
62 Warming
65 Warming