UTLS Group Meetings

The NCAR/ACOM UTLS group hosts a quasi-weekly informal science discussion.  Meetings are held in hybrid format, with in-person attendance in FL0-2108 or online using Google Meet (see emailed meeting links from Ren Smith and Victoria Treadaway).

Date Speaker Title / Topic
Feb 9 Bill Randel (NCAR/ACOM) Recent changes to the stratospheric circulation (discussion of Plöger and Garny 2022)
Mar 2 Paul Konopka (FZ Jülich) Stratospheric Moistening after 2000
Mar 9 Ren Smith (NCAR/ACOM) Evaluating the model representation of Asian monsoon UTLS transport and composition using StratoClim (2017) airborne in situ observations
Mar 23 Jianghanyang Li (NOAA/CIRES) A novel, cost-effective analytical method for measuring high-resolution vertical profiles of stratospheric trace gases using a GC-ECD
Mar 30 Katie Smith (U Miami)

 UTLS Whole Air Sampler Observations

Apr 13 Carly KleinStern (U Chicago) Temperature and Tracer Variations during the Overflight of Typhoon Hinnamnor
Apr 20 Oliver Eppers (MPIC) Chemical composition of aerosol particles associated with the Asian summer monsoon observed by ERICA
May 11 Gregg Schill (NOAA/CSL) PALMS-NG Observations from ACCLIP
June 15 Qing Liang (NASA GSFC) Global modeling of very-short-lived halogens and the role of Asian Summer Monsoon
June 22 Manish Naja (Aryabhatta Research Institute, India) Contribution of different sources over a mountain site (Nainital) in the central Himalaya
July 11 Ling Zou (FZ Jülich) Reanalysis Tropopause Data Repository and the Variability of the Tropical Tropopause from 1980 to 2021
July 18 Andrea Gordon and Emily Tinney (U Oklahoma)

Gordon: Examination of Cross-Tropopause Transport from DCOTSS In-situ Observations of Active Overshooting Convection

Tinney: Climatology, Sources, and Transport Characteristics of Observed Water Vapor Extrema in the Lower Stratosphere

July 25 Marta Abalos (Universidad Complutense de Madrid, Spain) Seasonality of future trends in lower stratospheric wave drag
Sep 26 Joowan Kim (Kongju National University, Korea) Relationship between TTL ozone and stratospheric water vapor: Insight from CCMI models
Oct 17 Colin Gurganus (NOAA CSL) Insights into Carbonyl Sulfide (OCS) Distribution and Sources in the Asian Summer Monsoon (ASM) Region: Evidence from Elevated Levels Observed in the UTLS during the ACCLIP Campaign
Oct 24 Yunqian Zhu (CIRES / NOAA CSL) Evaluating the importance of nitrate aerosol in the upper troposphere and lower stratosphere during the Asian summer monsoon season
Oct 31 Joowan Kim (Kongju National University, Korea) Ozonesonde Measurements during the ACCLIP Campaign and Their Applications
Nov 14 Eleanor Waxman (NOAA CSL) Ozone tendencies in the UTLS during ACCLIP
Dec 5 Alexandre Baron (CIRES / NOAA CSL) The Uncommon Optical and Microphysical Properties of the Hunga-Tonga Aerosol
Dec 12 n/a No Meeting - AGU
Jan 19 Bill Randel (NCAR/ACOM) Discussion of Vortex Behavior in the ASMA (Siu and Bowman 2020 & Rupp and Haynes 2021)
Jan 26 Xinyue Wang (NCAR/ACOM) The Dynamics of Eastward Eddy Shedding from the ASMA
Feb 2 Eric Ray (NOAA/CSL) Age spectra from SEAC4RS trace gas measurements
Feb 9 Victoria Treadaway (U. Miami) Discussion of Ozone-Depleting Substances in the ASMA UTLS (Adcock et al 2020) (PDF slides)
Feb 16 Qing Liang (NASA GSFC) The Impact of the Asian Summer Monsoon and Typhoons on the UT/LS Chemical Composition
Feb 23 Ren Smith (NCAR/ACOM) Discussion of Confinement and Transport of Air in the ASMA (Legras and Bucci 2020) (PDF slides)
Mar 2 Paul Newman (NASA GSFC) O3 and H2O relationship based diagnostic of stratosphere-troposphere-transition layer
Mar 16 Troy Thornberry (NOAA/ESRL) Discussion of observed new particle formation in the ASMA UTLS (Weigel et al 2020) (PDF slides)
Mar 30 Christina Williamson (NOAA/CSL) The ATAL within the 2017 ASMA derived from airborne observations (Mahnke et al 2021) (PDF slides)
April 13 Nick Davis (NCAR/ACOM) Specified dynamics scheme impacts on wave-mean flow dynamics, convection, and tracer transport in CESM2 (WACCM6)
April 20  Yutian Wu (Columbia) Fast transport pathways into the Northern Hemisphere UTLS during northern summer (Wu et al., 2020)
April 27 Mian Chin (NASA GSFC) Understanding the aerosol composition in ATAL with integrated modeling and observations from field campaigns (PPT slides)
May 4 Laura Pan (NCAR) Asian Monsoon Transport group discussion
May 18 Holger Vömel (NCAR/EOL) Revisiting ozone sonde measurements: Uncertainties and challenges for the upper troposphere and lower stratosphere (PDF slides)
June 29 Sofia Chelpon (CUNY) and Ren Smith (NCAR/ACOM) Characterization and Evaluation of Convective Transport Time Scales over the Tropical Western Pacific (PDF slides)
Feb 27 Dina Khordakova (Juelich) MOSES: Modular observation solutions for earth systems - a facility for the investigation of extreme weather events
Mar 14 Richard Newton Tropospheric temperature inversions in the Indian Monsoon - A climatology from GPS radio occultation measurements from 2001 to 2018
Apr 12 Xun Wang (TAMU) Impact of convectively lofted ice on the seasonal cycle of tropical lower stratospheric water vapor
Jun 19 Aurelien Podglajen (Juelich) Retrieving the age of air spectrum from tracers
Jul 25
Eric Jensen
Using in situ measurements to evaluate the Lagrangian dry point approach for calculating the stratospheric-entry water vapor concentration
Aug 14
Xinyue Wang
Fast transport into the lower stratosphere-upper troposphere over North America during northern summer
Sept 25
Wandi Yu
Influence of convection on stratospheric water vapor in the North American monsoon
Jan 24 Shawn Honomichl A Transport Pathway for Polluted Air from the Asian Summer Monsoon Anticyclone to the Global UTLS
Jan 31 Eric Ray (NOAA) The unexpected recent changes in the decline of CFC-11: New emissions, stratospheric loss variability or both?
Feb 14 Daniele Visioni (Universita' dell'Aquila, Italy) Chemical and dynamical side effects of stratospheric sulfate geoengineering: changes in upper tropospheric ice
Feb 28 Bill Randel Mainz UTLS workshop highlights summary
April 11 Sasha Madronich "Volatile chemical products emerging as largest petrochemical source of urban organic emissions” by McDonald et al.
April 27 Mingmin Zou (CAS/RADI) Greenhouse Gas Research Planned in Chinese Earth Observing Satellite GaoFen-5 Program
May 9 Joan Alexander (NWRA),Sean Davis (NOAA), and Lars Kalnajs (LASP) Stratéole-2: Tropical UTLS Measurements from Long Duration Superpressure Balloons
June 6 Bill Randel Discussion of a new paper
June 20  Martina Kraemer (Juelich) The Asian Monsoon airborne field campaign StratoClim 2017 and observations of ice cloud properties
July 10 Joowan Kim (Kongju National University, Korea) The Madden-Julian Oscillation’s influences on Stratospheric Moisture 
July 18  Yutian Wu (Columbia)
What is the transport pathway into the UTLS during northern summer?
July 24  Johnny Luo (CCNY) On the Use of Chemical Tracers to Diagnose Convective Transport Transit Time Spectrum over the Tropical Western Pacific
Aug 1 Daniel Phoenix (OU) Impacts of Tropopause-Penetrating Convection on the Chemical Composition of the Upper Troposphere and Lower Stratosphere
Aug 7 Cameron Homeyer (OU) A 10-year Ground-based Radar Climatology of Convective Penetration of Stratospheric Intrusions and Associated Large-Scale Transport over the CONUS

Aug 17


Marta Abalos (Universidad Complutense de Madrid, Spain) Impact of ozone depleting substances on the stratospheric Brewer-Dobson circulation (3:30 pm as ACOM seminar)
Nov 6 (Tuesday)  Bill Randel And Mijeong Park
Beginning look at the new SAGE III data 
Nov 21   Happy Thanksgiving 

Nov 29


Sabine Robrecht (Juelich, Germany) Might stratospheric ozone loss occur in mid-latitude summer today or in a future with or without geoengineering?
Dec 4 (Tuesday) Kimberlee Dube (Univ. of Saskatchewan, Canada) Stratospheric NO2 measurements from SAGE and OSIRIS
Jan 18 Laura Pan Asian summer monsoon Chemistry Climate Impact Project (ACCLIP)
Jan 25 Peter Hitchcock Some dynamical insights on the recent disruption of the QBO from an idealized model
Feb 15 Mengchu Tao A Lagrangian model diagnosis of stratospheric contributions to the tropical middle tropospheric air
Mar 2 Marta Abalos Using e90 to study UTLS tracer transport in WACCM
Mar15 Steve Massie Observational Evidence of 3D Cloud Effects in Orbiting Carbon Observatory
Measurements of CO2
Apr 12 Chengji Liu (CSU)  Synoptic formation of double tropopauses 
July 11 Chuntao Liu (TAMUCC)
Properties of different types of precipitation systems revealed by the Global Precipitation Mission observations
July 25 Laura Pan Lapse rate vs coldpoint: A tale of two tropical tropopause definitions told by tracers
Aug 4 Valeria Donets (U Miani) Shear line facilitated transport of reactive trace gases from East Asia into the deep tropics
Aug 7 Gretchen Mullendore (UND)
Defining the tropopause in studies of deep convection
Aug 16 Rainer Volkamer (CU) BrO and Bry profiles over the Western Pacific: Relevance of Inorganic Bromine Sources and a Bry Minimum in the Aged Tropical Tropopause Layer
Aug 18 Javier Garcia-Serrano (Barcelona Supercomputing Center) On the Hemispheric Scale of the Winter North Atlantic Oscillation
Aug 24 Olga Tweedy (JHU) Does ENSO influence summer-time ozone in the tropical lower-stratosphere?
Aug. 30  John Albers (NOAA) Trends in the Seasonality of the Brewer-Dobson Circulation Due to Radiative-Dynamical Feedbacks
Sep 19

George Kiladis (NOAA)


Variability of Stratospheric mixed Rossby-gravity, Kelvin, and external Rossby modes and connections with the troposphere
Sep 20 (2:30 pm) Liz Moyer (U Chicago) Early results from the StratoClim campaign over the Asian monsoon
Sep 27 Laura Pan Space-Time Variability of UTLS Chemical Distribution in the Asian Summer Monsoon Viewed by Limb and Nadir Satellite Sensors
Oct 11 Open  
Jan 6 Bill Randel Vernier, J. -P. .JGR 2015
Jan 20 Thomas Birner Characteristics of lower stratospheric transport as inferred from age of air spectra
Feb 3  Eric jensen Processes Controlling the Distribution of Relative Humidity in the Tropical Tropopause Layer
Feb 17 Laura Pan Discussion of an Asian monsoon dynamics paper: Liu YM, Hoskins BJ, Blackburn M (2007) Impact of Tibetan orography and heating on the summer flow over Asia. J Meteorol Soc  Jpn (Special 125th Anniversary Issue, Invited Review Articles) 85B:1–19
Feb 25 Jasna Pittman (NWRA) Input into the Stratosphere As Revealed by ATTREX Observations of Greenhouse Gases
March 2 Jeremiah Sjorberg (NOAA) Stratosphere-troposphere coupling insights from both a Kelvin wave momentum flux dataset and the Sudden Stratospheric Warming Compendium
March 16  Matthias Nuetzel (DLR) Connection of (lower level) monsoon with climate indices - possible pathways to explore the UTLS response on interannual time scales
March 30 Aurelien Podglajen (LMD) Lagrangian temperature and vertical velocity fluctuations due to gravity
waves in the lower stratosphere
April 12 Qiang Fu (U Washington) Tropical lower-stratospheric H2O & tropical tropopause layer cirrus: A COSMIC perspective
April 27  Laura Pan Prather et al. : An atmospheric chemist in search of the tropopause, JGR 2011:
May 11 Chuck Bardeen Initial evaluation of UTLS temperature, water vapor and clouds in CESM6
June 16 Cameron Homeyer (OU) Procuring a Toolbox for Studying Tropopause-Penetrating Convection : Methods, Observations, and Models
July 13 Bill Randel Relationships between outgoing longwave radiation and diabatic heating in reanalyses
July 20 Minghui Diao (SJSU) Comparisons of ice supersaturation and ice microphysical properties between in-situ observations and a hierarchy of models: a cloud-resolving model, WRF and CAM5
Agust 23 Johnny Luo (CCNY) Satellite-Based Estimation of Convective and Large-Scale Mass Fluxes and Implications for Convective Transport of Composition
August 25 Lorenzo Polvani (Columbia) The impact of ozone depleting substances on tropical upwelling, as revealed by the absence of lower stratospheric cooling since the late 1990s
Sept. 14 Bernd Kaercher (DLR) Homogeneous Ice Formation in Supercooled Water Clouds
Sept. 28 Chengjun Yang (STU, China) The signal of the Madden-Julian Oscillation in Southern middle atmosphere during austral winter
Oct 12 John Bergman The viability of trajectory analysis for diagnosing dynamical and chemical influences on ozone concentrations in the tropical UTLS: Lessons learned in complex systems analysis
Oct 26 Marta Abalos Phase-speed spectra of eddy tracer fluxes linked to isentropic stirring and mixing in the upper troposphere and lower stratosphere
Nov 9 Eric Jensen An overview of the POSIDON WB-57 campaing in Guam
July 17 Daniel Gilford (MIT) Nonlocal radiative effects of abrupt drops in tropical tropopause layer water vapor and ozone
July 24 Aditi Sheshadri (MIT) Variability of the polar stratospheric vortex and its impact on surface climate patterns in an idealized AGCM
Aug 5 Claudia Stephan (CU) Gravity Waves Generated by Convection: A New Idealized Model Tool and Direct Validation with Satellite Observations
Sept 2 Ken Minschwaner (NM Tech) The hunt for laminae in UTLS ozonesonde measurements:
What can they tell us about transport and dynamics?
Sept 16 Mijeong Park  and Bill Randel Variability of reactive nitrogen species linked to the stratospheric QBO
Sept 30 Marta Abalos Interannual variability of effective diffusivity in the UTLS
Oct 14 Joowan Kim Large-scale temperature and moisture responses to deep convection in the tropical UTLS: observations from COSMIC GPS RO and Aura MLS
Oct 28 Thomas Birner (CSU) The discovery of the stratosphere
Nov 5 Rafael Fernandez
Global Distributions of Very Short-Lived Halogens: from the Ocean Surface to the Tropical Tropopause Layer
Nov 17 Peter Hitchcock
(U. Cambridge)
A radiative origin for the double-peak structure of upwelling in the tropical lower stratosphere


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UTLS Research