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Full-Text Articles in Physics
Steady-State Aerosol Distributions In The Extra-Tropical, Lower Stratosphere And The Processes That Maintain Them, J. Wilson, Shan-Hu Lee, J. Reeves, C. Brock, H. Jonsson, B. Lafleur, M. Loewenstein, J. Podolske, E. Atlas, K. Boering, G. Toon, D. Fahey, T. Bui, G. Diskin, F. Moore
Steady-State Aerosol Distributions In The Extra-Tropical, Lower Stratosphere And The Processes That Maintain Them, J. Wilson, Shan-Hu Lee, J. Reeves, C. Brock, H. Jonsson, B. Lafleur, M. Loewenstein, J. Podolske, E. Atlas, K. Boering, G. Toon, D. Fahey, T. Bui, G. Diskin, F. Moore
Shan-Hu Lee
Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and sedimentation of particles in the extra-tropical overworld north of 45 N are found to maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. …
Isoprene Suppression Of New Particle Formation In A Mixed Deciduous Forest, V. P. Kanawade, B. T. Jobson, A. B. Guenther, M. E. Erupe, S. N. Pressley, S. N. Tripathi, Shan-Hu Lee
Isoprene Suppression Of New Particle Formation In A Mixed Deciduous Forest, V. P. Kanawade, B. T. Jobson, A. B. Guenther, M. E. Erupe, S. N. Pressley, S. N. Tripathi, Shan-Hu Lee
Shan-Hu Lee
Production of new particles over forests is an important source of cloud condensation nuclei that can affect climate. While such particle formation events have been widely observed, their formation mechanisms over forests are poorly understood. Our observations made in a mixed deciduous forest with large isoprene emissions during the summer displayed a surprisingly rare occurrence of new particle formation (NPF). Typically, NPF events occur around noon but no NPF events were observed during the 5 weeks of measurements. The exceptions were two evening ultrafine particle events. During the day, sulfuric acid concentrations were in the 106 cm−3 range with very …
The Effect Of Trimethylamine On Atmospheric Nucleation Involving H2so4, M. E. Erupe, A. A. Viggiano, Shan-Hu Lee
The Effect Of Trimethylamine On Atmospheric Nucleation Involving H2so4, M. E. Erupe, A. A. Viggiano, Shan-Hu Lee
Shan-Hu Lee
Field observations and quantum chemical calculations have shown that organic amine compounds may be important for new particle formation involving H2SO4. Here, we report laboratory observations that investigate the effect of trimethylamine (TMA) on H2SO4-H2O nucleation made under aerosol precursor concentrations typically found in the lower troposphere ([H2SO4] of 106−107 cm−3; [TMA] of 180–1350 pptv). The threshold [H2SO4] needed to produce the unity J was from 106−107 cm−3 and the slopes of Log …
New Particle Growth And Shrinkage Observed In Subtropical Environments, L. H. Young, Shan-Hu Lee, V. P. Kanawade, T-C. Hsiao, Y. L. Lee, B-F. Hwang, Y-J. Liou, H-T. Hsu, P-J. Tsai
New Particle Growth And Shrinkage Observed In Subtropical Environments, L. H. Young, Shan-Hu Lee, V. P. Kanawade, T-C. Hsiao, Y. L. Lee, B-F. Hwang, Y-J. Liou, H-T. Hsu, P-J. Tsai
Shan-Hu Lee
We present the first systematic analysis for new particle formation (NPF), growth and shrinkage of new particles at four different sites in subtropical central Taiwan. A total of 14 NPF events were identified from 137 days of ambient measurements during a cold and warm season. The measured formation rates of 10 nm particles (J10) and growth rates were in the range of 4.4–30 cm−3s−1 and 7.4–24 nm h−1, respectively. The onset of NPF events coincided with decreases of condensation sink (CS) and increases of SO2 under enhanced atmospheric mixing and dilution. …
Ternary Homogeneous Nucleation Of H2so4, Nh3, And H2o Under Conditions Relevant To The Lower Troposphere, D. Benson, J. Yu, A. Markovich, Shan-Hu Lee
Ternary Homogeneous Nucleation Of H2so4, Nh3, And H2o Under Conditions Relevant To The Lower Troposphere, D. Benson, J. Yu, A. Markovich, Shan-Hu Lee
Shan-Hu Lee
Ternary homogeneous nucleation (THN) of H2SO4, NH3 and H2O has been used to explain new particle formation in various atmospheric regions, yet laboratory measurements of THN have failed to reproduce atmospheric observations. Here, we report first laboratory observations of THN made under conditions relevant to the lower troposphere ([H2SO4] of 106–107 cm−3, [NH3] of 0.08–20 ppbv, and a temperature of 288 K). Our observations show that NH3 can enhance atmospheric H2SO4aerosol nucleation and the enhancement factor (EF) in nucleation rate (J) due to NH3 (the ratio of Jmeasured with vs. without NH3) increases linearly with increasing [NH3] and increases with …
Uncertainty Associated With Modeling The Global Ionosphere, Janelle Jenniges, Ariel Acebal, Larry Gardner, Robert Schunk, Lie Zhu
Uncertainty Associated With Modeling The Global Ionosphere, Janelle Jenniges, Ariel Acebal, Larry Gardner, Robert Schunk, Lie Zhu
Janelle V Jenniges
A study has been conducted of the effect that different physical assumptions have on global models of the electron density distribution. The study was conducted with the Ionosphere Forecast Model (IFM) and the Ionosphere Plasmasphere Model (IPM) developed by Utah State University. Both physics-based, time-dependent, global models use the same empirical models for the neutral atmosphere (MSIS) and neutral wind (Horizontal Wind Model, HWM), but the altitude range, thermal structure, number of ion species, and magnetic 2ield are different. The IFM covers the altitude range from 90-1400 km, calculates the densities for four ions (NO+, O2+, N2+, O+), has a …
Usu Grad Student, Researchers Collect Project Data At South Pole, Kevin Opsahl
Usu Grad Student, Researchers Collect Project Data At South Pole, Kevin Opsahl
Jonathan Pugmire
No abstract provided.
Usu Grad Student Travels To South Pole, Kylie Conway
Usu Grad Student Travels To South Pole, Kylie Conway
Jonathan Pugmire
No abstract provided.
Usu Team Travels To South Pole To Measure Gravity Waves, Nancy Van Valkenburg
Usu Team Travels To South Pole To Measure Gravity Waves, Nancy Van Valkenburg
Jonathan Pugmire
No abstract provided.
Evaluation Of The In Situ Ichthyoplankton Imaging System (Isiis): Comparison With The Traditional (Bongo Net) Sampler, Robert K. Cowen, Adam T. Greer, Cedric M. Guigand, Jonathan A. Hare, David E. Richardson, Harvey J. Walsh
Evaluation Of The In Situ Ichthyoplankton Imaging System (Isiis): Comparison With The Traditional (Bongo Net) Sampler, Robert K. Cowen, Adam T. Greer, Cedric M. Guigand, Jonathan A. Hare, David E. Richardson, Harvey J. Walsh
Adam T. Greer
Plankton and larval fish sampling programs often are limited by a balance between sampling frequency (for precision) and costs. Advancements in sampling techniques hold the potential to add considerable efficiency and, therefore, add sampling frequency to improve precision. We compare a newly developed plankton imaging system, In Situ Ichthyoplankton Imaging System (ISIIS), with a bongo sampler, which is a traditional plankton sampling gear developed in the 1960s. Comparative sampling was conducted along 2 transects ~30–40 km long. Over 2 days, we completed 36 ISIIS tow-yo undulations and 11 bongo oblique tows, each from the surface to within 10 m of …