Index Catalog // ScholarsArchive@OSU

Refinements to Ice Particle Mass Dimensional and Terminal Velocity Relationships for Ice Clouds. Part I: Temperature Dependence

Creator:: Heymsfield, Andrew J., Bansemer, Aaron, and Twohy, Cynthia
Abstract:: This two-part study attempts to find appropriate mass dimension and terminal velocity relationships that, when considered together with particle size distributions (PSD), agree with coincident measurements of ice water content (IWC), and with variables related to higher moments such as the mean mass-weighted fall speed. Reliable relationships are required for...
Resource Type:: Article
Full Text:: BANSEMER National Center for Atmospheric Research,* Boulder, Colorado CYNTHIA H. TWOHY College of

Upper-tropospheric relative humidity observation and implications for cirrus ice nucleation

Creator:: Heymsfield, Andrew J., Miloshevich, Larry M., Twohy, Cynthia, Sachse, Glen, and Oltmans, Samuel
Abstract:: Relative humidity (RH) measurements acquired in orographic wave cloud and cirrus environments are used to investigate the temperature‐dependent RH required to nucleate ice crystals in the upper troposphere, RHnuc(T). High ice‐supersaturations in clear air—conducive to the maintenance of aircraft contrails yet below RHnuc and therefore insufficient for cirrus formation—are not...
Resource Type:: Article
Full Text:: Andrew J. Heymsfield, Larry M. Miloshevich, and Cynthia Twohy National Center for Atmospheric Research

Environmental conditions required for contrail formation and persistance

Creator:: Jensen, Eric J., Toon, Owen B., Kinne, Stefan, Sachse, Glen W., Anderson, Bruce E., Chan, K. Roland, Twohy, Cynthia, Gandrud, Bruce W., Heymsfield, Andrew J., and Maike-Lye, Richard C.
Abstract:: The ambient temperatures and humidities required for contrail formation and persistence are determined from in situ measurements during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) experiment. Ambient temperatures and water vapor concentrations were measured with the meteorological measurement system, a laser hygrometer, and a cryogenic hygrometer (all...
Resource Type:: Article
Full Text:: Stefan Kinne, • Glen W. Sachse, 4 Bruce E. Anderson, 4 K. Roland Chan, • Cynthia H. Twohy, s Bruce

The role of heterogeneous freezing nucleation in upper troposphereic clouds : inferences from SUCCESS

Creator:: DeMott, Paul J., Rogers, David C., Kreidenweis, Sonia M., Chen, Yalei, Twohy, Cynthia, Heymsfield, Andrew J., Chan, K. Roland, and Baumgardner, Darrel
Abstract:: A temperature spectrum if heterogeneous freezing nuclei concentrations in continental air in the upper troposphere was determined based on airborne measurements. Numerical model simulations incorporating ice formation by heterogeneous and homogeneous freezing of deliquesced soluble aerosol particles were performed to investigate the effect of the heterogeneous freezing nuclei were predicted...
Resource Type:: Article
Full Text:: Atmospheric Science, Colorado State University, Fort Collins, CO Cynthia H. Twohy, Darrel Baumgardner, and

Evidence of nitric acid uptake in warm cirrus anvil clouds during the NASA TC4 campaign

Creator:: Scheuer, Eric, Dibb, Jack E., Twohy, Cynthia, Rogers, David C., Heymsfield, Andrew J., and Bansemer, Aaron
Abstract:: Uptake ofHNO₃ onto cirrus ice may play an important role in tropospheric NOx cycling. Discrepancies between modeled and in situ measurements of gas‐phase HNO₃ in the troposphere suggest that redistribution and removal mechanisms by cirrus ice have been poorly constrained. Limited in situ measurements have provided somewhat differing results and...
Resource Type:: Article
Full Text:: Cynthia Twohy,2 David C. Rogers,3 Andrew J. Heymsfield,4 and Aaron Bansemer4 Received 24 June 2009

Ice in Clouds Experiment—Layer Clouds. Part I: Ice Growth Rates Derived from Lenticular Wave Cloud Penetrations

Creator:: Heymsfield, Andrew J., Field, Paul R., Bailey, Matt, Rogers, Dave, Stith, Jeffrey, Twohy, Cynthia, Wang, Zhien, and Haimov, Samuel
Abstract:: Lenticular wave clouds are used as a natural laboratory to estimate the linear and mass growth rates of ice particles at temperatures from -20° to -32°C and to characterize the apparent rate of ice nucleation at water saturation at a nearly constant temperature. Data are acquired from 139 liquid cloud...
Resource Type:: Article
Full Text:: . FIELD,1 MATT BAILEY,# DAVE ROGERS,* JEFFREY STITH,* CYNTHIA TWOHY,@ ZHIEN WANG,& AND SAMUEL HAIMOV

Effective Radius of Ice Cloud Particle Populations Derived from Aircraft Probes

Creator:: Heymsfield, Andrew J., Schmitt, Carl, Bansemer, Aaron, van Zadelhoff, Gerd-Jan, McGill, Matthew J., Twohy, Cynthia, and Baumgardner, Darrel
Abstract:: The effective radius (r[subscript]e) is a crucial variable in representing the radiative properties of cloud layers in general circulation models. This parameter is proportional to the condensed water content (CWC) divided by the extinction (σ). For ice cloud layers, parameterizations for r[subscript]e have been developed from aircraft in situ measurements...
Resource Type:: Article
Full Text:: Bilt, Netherlands MATTHEW J. MCGILL NASA Goddard Space Flight Center, Greenbelt, Maryland CYNTHIA

Observation of playa salts as nuclei in orographic wave clouds

Creator:: Pratt, Kerri A., Twohy, Cynthia, Murphy, Shane M., Moffet, Ryan C., Heymsfield, Andrew J., Gaston, Cassandra J., DeMott, Paul J., Field, Paul R., Henn, Tobias R., Rogers, David C., Gilles, Mary K., Seinfeld, John H., and Prather, Kimberly A.
Abstract:: During the Ice in Clouds Experiment‐Layer Clouds (ICE‐L), dry lakebed, or playa, salts from the Great Basin region of the United States were observed as cloud nuclei in orographic wave clouds over Wyoming. Using a counterflow virtual impactor in series with a single‐particle mass spectrometer, sodium‐potassium‐magnesium‐calcium‐chloride salts were identified as...
Resource Type:: Article
Full Text:: orographic wave clouds Kerri A. Pratt,1,2 Cynthia H. Twohy,3 Shane M. Murphy,4,5 Ryan C. Moffet,6 Andrew J

Ice nucleation processes in upper tropospheric wave-clouds observed during SUCCESS

Creator:: Jensen, E. J., Toon, O. B., Tabazadeh, A., Sachse, G. W., Andersen, B. E., Chan, K. R., Twohy, Cynthia, Gandrud, Bruce W., Aulenbach, S. M., Heymsfield, Andrew J., Hallett, J., and Gary, B.
Abstract:: We have compared in situ measurements near the leading-edges of wave-clouds observed during the SUCCESS experiment with numerical simulations. Observations of high supersaturations with respect to ice (> 50%) near the leading edge of a very cold wave cloud (T < -60°C) are approximately consistent with recent theoretical and laboratory...
Resource Type:: Article
Full Text:: . Jensen •, O. B. TooI12, A. Tabazadeh •, G. W. Sachse s, B. E. Anderson • K. R. Chan •, C. W. Twohy 4, B

In Situ Chemical Characterization of Aged Biomass-Burning Aerosols Impacting Cold Wave Clouds

Creator:: Pratt, Kerri A., Heymsfield, Andrew J., Twohy, Cynthia, Murphy, Shane M., DeMott, Paul J., Hudson, James G., Subramanian, R., Wang, Zhien, Seinfeld, John H., and Prather, Kimberly A.
Abstract:: During the Ice in Clouds Experiment–Layer Clouds (ICE-L), aged biomass-burning particles were identified within two orographic wave cloud regions over Wyoming using single-particle mass spectrometry and electron microscopy. Using a suite of instrumentation, particle chemistry was characterized in tandem with cloud microphysics. The aged biomass-burning particles comprised ~30%–40% by number...
Resource Type:: Article
Full Text:: Biomass-Burning Aerosols Impacting Cold Wave Clouds KERRI A. PRATT,a,b ANDREW J. HEYMSFIELD,c CYNTHIA H

ScholarsArchive@OSU

Refinements to Ice Particle Mass Dimensional and Terminal Velocity Relationships for Ice Clouds. Part I: Temperature Dependence

Upper-tropospheric relative humidity observation and implications for cirrus ice nucleation

Environmental conditions required for contrail formation and persistance

The role of heterogeneous freezing nucleation in upper troposphereic clouds : inferences from SUCCESS

Evidence of nitric acid uptake in warm cirrus anvil clouds during the NASA TC4 campaign

Ice in Clouds Experiment—Layer Clouds. Part I: Ice Growth Rates Derived from Lenticular Wave Cloud Penetrations

Effective Radius of Ice Cloud Particle Populations Derived from Aircraft Probes

Observation of playa salts as nuclei in orographic wave clouds

Ice nucleation processes in upper tropospheric wave-clouds observed during SUCCESS

In Situ Chemical Characterization of Aged Biomass-Burning Aerosols Impacting Cold Wave Clouds

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