JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Oral

A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS09] [EE] Stratosphere - Troposphere Interaction

Wed. May 24, 2017 3:30 PM - 5:00 PM 303 (International Conference Hall 3F)

convener:Nawo Eguchi(Kyushu University), Rei Ueyama(NASA Ames Research Center), Sean M Davis(NOAA Boulder), Seok Woo Son(Seoul National University), Chairperson:Seok-Woo Son(Seoul National University), Chairperson:Sean Davis(NOAA Boulder), Chairperson:Nawo Eguchi(Kyushu University), Chairperson:Mark Schoeberl (Science and Technology Corporation)

3:45 PM - 4:00 PM

[AAS09-20] Ice Nucleation in the Tropical Tropopause Layer: Implications for cirrus occurrence, cirrus microphysical properties, and dehydration of air entering the stratosphere

★Invited papers

*Eric J Jensen1, Bernd Kaercher2, Rei Ueyama3, Leonhard Pfister1 (1.NASA Ames Research Center, 2.Deutches Zentrum fur Luft- und Raumfart, 3.Bay Area Environmental Research Institute)

Keywords:Ice nucleation, Heterogeneous nucleation, Dehydration

Recent laboratory experiments have advanced our understanding of the physical properties and ice nucleating abilities of aerosol particles at low temperatures. In particular, aerosols containing organics will transition to a glassy state at low temperatures, and these glassy aerosols are moderately effective as ice nuclei. These results have implications for ice nucleation in the cold Tropical Tropopause Layer (TTL; 13-19 km). We have developed a detailed cloud microphysical model that includes heterogeneous nucleation on a variety of aerosol types and homogeneous freezing of aqueous aerosols. This model has been incorporated into one-dimensional simulations of cirrus and water vapor driven by meteorological analysis temperature and wind fields. The model includes scavenging of ice nuclei by sedimenting ice crystals. The model is evaluated by comparing the simulated cloud properties and water vapor concentrations with aircraft and satellite measurements. In this presentation, I will discuss the relative importance of homogeneous and heterogeneous ice nucleation, the impact of ice nuclei scavenging as air slowly ascends through the TTL, and the implications for the final dehydration of air parcels crossing the tropical cold-point tropopause and entering the tropical stratosphere.