About

Christopher Nowotarski is an Associate Professor in the Department of Atmospheric Sciences at Texas A&M University. His research is focused on understanding the structure and dynamics of convective storms in midlatitudes, with an emphasis on supercell thunderstorms and the development of low-level rotation related to tornado genesis. His work involves the use of idealized simulations with cloud-resolving models, as well as analysis of observed data collected through operational and research field experiments. Nowotarski's research interests include severe convection, tornado environments, tropical cyclone tornadoes, large-scale influences on severe weather events, machine learning techniques for probabilistic forecasting, data assimilation in convection-allowing models, and modeling effects of permafrost changes on Arctic meteorology. He holds a Ph.D., M.S., and B.S. in Meteorology from Pennsylvania State University and has contributed extensively to the field through presentations and publications.

Research topics

• Meteorology
• Geology
• Mechanics
• Physics
• Climatology
• Geography
• Environmental science
• Atmospheric sciences
• Oceanography

Selected publications

• Supplementary material to "Aerosol Vertical Distributions Shaped by Boundary Layer Dynamics in a Coastal Urban Environment: Insights from the TRACER Campaign"

  2026-04-02

  articleOpen access
  PublisherDOI

• Understanding aerosol properties in convective outflows during TRACER

  Figshare · 2026-01-01

  articleOpen access

  Convective outflow boundaries commonly form across the southeastern U.S., often originating from storms initiated along sea-breeze fronts. As outflows spread, merge, and collide, they frequently trigger secondary convection in air masses already modified by primary storm outflow. This resulting air mass carries a distinctive aerosol population, which can influence the development of secondary convective cells. During the U.S. DOE TRACER field campaign in summer 2022, we investigated how outflows affect aerosol size, composition, and hygroscopicity across Greater Houston, Texas. Using a novel detection algorithm, we identified and verified 72 outflow boundaries from surface meteorological observations. In the relatively simple continental environment northwest of Houston, a common relationship emerged between CCN-inferred hygroscopicity (<i>κ</i>) and size-resolved aerosol concentrations. The <i>κ</i> of aerosols typically decreased in size ranges where aerosol concentrations increased following outflow passage and increased where concentrations decreased. In contrast, at the Atmospheric Radiation Measurement’s (ARM) fixed site in La Porte, Texas, the aerosol response depended on outflow direction, shaped by concentrated industrial and shipping activity to the north and south/southeast along the Houston Ship Channel. Concurrent size distribution and composition changes suggested case-specific variability in <i>κ</i>, with either reinforcing or offsetting effects. Outflows passing over industrial/shipping sectors often promoted less hygroscopic aerosol populations while cleaner residential outflows often favored more hygroscopic aerosol populations. These results highlight key aerosol changes following outflow passage, providing a foundation for improved understanding of aerosol-cloud interactions related to secondary convection initiation along or in the wake of outflow boundaries.

  PublisherDOI

• Understanding aerosol properties in convective outflows during TRACER

  Aerosol Science and Technology · 2026-01-20

  articleOpen access

  Convective outflow boundaries commonly form across the southeastern U.S., often originating from storms initiated along sea-breeze fronts. As outflows spread, merge, and collide, they frequently trigger secondary convection in air masses already modified by primary storm outflow. This resulting air mass carries a distinctive aerosol population, which can influence the development of secondary convective cells. During the U.S. DOE TRACER field campaign in summer 2022, we investigated how outflows affect aerosol size, composition, and hygroscopicity across Greater Houston, Texas. Using a novel detection algorithm, we identified and verified 72 outflow boundaries from surface meteorological observations. In the relatively simple continental environment northwest of Houston, a common relationship emerged between CCN-inferred hygroscopicity (<i>κ</i>) and size-resolved aerosol concentrations. The <i>κ</i> of aerosols typically decreased in size ranges where aerosol concentrations increased following outflow passage and increased where concentrations decreased. In contrast, at the Atmospheric Radiation Measurement’s (ARM) fixed site in La Porte, Texas, the aerosol response depended on outflow direction, shaped by concentrated industrial and shipping activity to the north and south/southeast along the Houston Ship Channel. Concurrent size distribution and composition changes suggested case-specific variability in <i>κ</i>, with either reinforcing or offsetting effects. Outflows passing over industrial/shipping sectors often promoted less hygroscopic aerosol populations while cleaner residential outflows often favored more hygroscopic aerosol populations. These results highlight key aerosol changes following outflow passage, providing a foundation for improved understanding of aerosol-cloud interactions related to secondary convection initiation along or in the wake of outflow boundaries.

  PublisherDOI

• Simulation of Water Vapor Transport to the Stratosphere by Overshooting Convection

  Journal of Geophysical Research Atmospheres · 2026-03-25

  articleOpen accessSenior author

  Abstract Deep convection that penetrates the tropopause (overshooting convection) transports water vapor and other tropospheric constituents to the upper troposphere and lower stratosphere (UTLS). Overshooting convection has chemical and radiative impacts on the UTLS, including the downward transport of ozone and hydration of the stratosphere. Currently, water vapor transport due to overshooting convection is not well quantified. In this study the Weather Research and Forecasting model (WRF) is used to simulate a Mesoscale Convective System (MCS) that formed on 9 June 2022 and produced multiple overshoots over the course of 12 hr, with radar echo tops reaching up to 5 km above the ERA5 tropopause. Observations from the NEXRAD radar system are used along with in situ aircraft measurements from the Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) project to validate the simulated overshooting convection and horizontal transport of the water vapor plume. Isentropic back trajectories are used to match water vapor enhancements to individual overshoots and the mass of the plume is calculated by subtracting the stratospheric background. In total, the model estimates that this storm injected 121 kt of water vapor into the stratosphere: 56 kt into the 370–380 K layer, 30 kt into the 380–390 K layer, and 35 kt above 390 K with enhancements simulated as high as the 445 K isentrope.

  PublisherDOI

• Transport to the Extratropical Stratosphere by Overshooting Storms in Idealized Simulations

  Journal of Geophysical Research Atmospheres · 2026-04-17

  articleOpen access

  Abstract Deep convection is a significant source of water to the extratropical stratosphere which can alter radiative properties and contribute to ozone loss. Previous studies find it responsible for 40% of mid‐latitude water vapor above 380K. However, the amount of hydration from individual storms and the mechanisms that initiate mixing is less understood. We use an idealized large eddy simulation with 100 m horizontal and vertical grid spacing to simulate a multicell storm with several overshooting tops (OTs) extending up to 2.5 km above the tropopause. Our goals are to determine the amount of water vapor and ice added to the stratosphere by this storm complex, identify how varying grid spacing affects the amount of hydration, and investigate the processes leading to irreversible mixing into the stratosphere. We find that, relative to the base state, an additional 33.7 kilotons of ice and 4.2 kilotons of water vapor are present in the stratosphere at the end of the simulation. For hydration similar to the 100‐m baseline simulation, 300‐m horizontal and 100‐m vertical grid spacing are necessary. Finally, the mechanism leading to hydration from individual OTs is shown to occur only after the initial overshoots begin to collapse. A region of positive buoyancy develops where previously overshooting cloud has descended, which is followed by a secondary upward movement of moistened air disconnected from the initial updraft. This process, not direct detrainment and sublimation of ice from the initial overshoot itself, triggers irreversible mixing in each case we investigate.

  PublisherDOI

• Understanding aerosol properties in convective outflows during TRACER

  Figshare · 2026-01-01

  articleOpen access

  Convective outflow boundaries commonly form across the southeastern U.S., often originating from storms initiated along sea-breeze fronts. As outflows spread, merge, and collide, they frequently trigger secondary convection in air masses already modified by primary storm outflow. This resulting air mass carries a distinctive aerosol population, which can influence the development of secondary convective cells. During the U.S. DOE TRACER field campaign in summer 2022, we investigated how outflows affect aerosol size, composition, and hygroscopicity across Greater Houston, Texas. Using a novel detection algorithm, we identified and verified 72 outflow boundaries from surface meteorological observations. In the relatively simple continental environment northwest of Houston, a common relationship emerged between CCN-inferred hygroscopicity (<i>κ</i>) and size-resolved aerosol concentrations. The <i>κ</i> of aerosols typically decreased in size ranges where aerosol concentrations increased following outflow passage and increased where concentrations decreased. In contrast, at the Atmospheric Radiation Measurement’s (ARM) fixed site in La Porte, Texas, the aerosol response depended on outflow direction, shaped by concentrated industrial and shipping activity to the north and south/southeast along the Houston Ship Channel. Concurrent size distribution and composition changes suggested case-specific variability in <i>κ</i>, with either reinforcing or offsetting effects. Outflows passing over industrial/shipping sectors often promoted less hygroscopic aerosol populations while cleaner residential outflows often favored more hygroscopic aerosol populations. These results highlight key aerosol changes following outflow passage, providing a foundation for improved understanding of aerosol-cloud interactions related to secondary convection initiation along or in the wake of outflow boundaries.

  PublisherDOI

• Aerosol Vertical Distributions Shaped by Boundary Layer Dynamics in a Coastal Urban Environment: Insights from the TRACER Campaign

  2026-04-02

  articleOpen access

  Abstract. Aerosol vertical distributions are a major source of uncertainty in quantifying aerosol–cloud–climate interactions. Using observations collected during the 2022 TRACER campaign in Houston, Texas, we investigate how Atmospheric boundary layer dynamics shape the vertical structure of aerosol populations in a coastal urban environment. Our lidar retrieval combines micropulse lidar backscatter with ground-based aerosol measurements to obtain aerosol concentration profiles. We introduce a new parameterized fitting function that captures the characteristic S-shaped aerosol profiles associated with boundary layer processes. This parameterization is applied to case studies demonstrating how boundary-layer dynamics, including turbulent mixing, capping inversion strength, and sea-breeze circulations, govern aerosol vertical distributions. Finally, we estimate aerosol vertical profiles from boundary layer height and gradients in potential temperature profile using our proposed aerosol profile parameterization function. These findings provide a physically grounded parameterization for inferring aerosol vertical profiles in locations where aerosol sampling is limited to surface measurements.

  PublisherDOI

• The Importance of an Ensemble Approach for Modeling Aerosol‐Convection Interactions

  Geophysical Research Letters · 2025-12-29

  articleOpen access

  Abstract Aerosol‐convection interactions modulate cloud microphysics, thermodynamics, and updraft intensity, contributing to climate‐scale aerosol‐radiative forcing. However, quantifying aerosol indirect effects in mixed‐phase deep convection remains challenging due to uncertainties in parameterized physics and initial conditions driving nonlinear evolution of convective processes. This study investigates the convective updraft sensitivity to random initial temperature perturbations using an idealized ensemble modeling framework informed by in situ thermodynamic and aerosol observations from the DOE TRACER field campaign. We analyze the impact of small‐scale initial perturbations on updraft velocity and supersaturation, and determine the ensemble size required to minimize stochastic internal variability. Results show that minor thermodynamic perturbations can produce updraft variability comparable to aerosol‐induced changes reported in prior work. An ensemble of 10 members sufficiently reduces variability, enabling robust investigation of aerosol‐related updraft invigoration and informing the design of future ensemble‐based aerosol‐convection interaction studies in environments with significant spatiotemporal mesoscale thermodynamic and aerosol heterogeneity.

  PublisherDOI

• Near-Cell Environments of Tropical Cyclone Tornadoes

  Journal of Operational Meteorology · 2025-04-10

  articleOpen access

  Accurately distinguishing and warning convective cells in the outer rainbands of landfalling tropical cyclones (TC) that will produce tornadoes (TCTORs) presents considerable challenges for forecasters. To enhance warning efforts, this study compares the near-cell environments between tornadic cells (including both warning hits and misses) and warned nontornadic cells (false alarms) in landfalling tropical cyclones in the contiguous United States from 2013 to 2020. For each cell, RAP analysis gridpoint proximity soundings were obtained to represent the near-cell environment and compared between tornadic and nontornadic cells. Warning skill with respect to various factors such as time of day, position relative to the TC center, distance from the nearest radar, and distance from the coast and year is also analyzed. Finally, this study characterizes the spatiotemporal distribution of sounding-derived convective parameters for TCTORs. Findings from this study indicate slight differences in the near cell environments between tornadic and nontornadic cells. Kinematic parameters, specifically the 0–6 km shear and effective storm-relative helicity, are more effective in distinguishing between tornadic and nontornadic near-cell environments than thermodynamic parameters. This distinction becomes most pronounced when comparing near-cell environments conducive to F/EF1+ tornadoes with nontornadic environments. Warning skill has improved with time over the analyzed period but tends to decrease farther from the TC center and the nearest NEXRAD WSR-88D. TC environments exhibit spatiotemporal variability across all environmental parameters. Convective instability is most prominent in the southeastern quadrant and increases with distance from the TC center. In contrast, shear and storm-relative-helicity is largest near the TC center and within the northeastern quadrant. The potential for near-storm environment parameters to discriminate between tornadic and nontornadic cells also varies spatiotemporally.

  PublisherDOI

• Studying Aerosol, Clouds, and Air Quality in the Coastal Urban Environment of Southeastern Texas

  Bulletin of the American Meteorological Society · 2025-08-04 · 3 citations

  article

  Abstract A multi-agency succession of field campaigns was conducted in southeastern Texas during July 2021 through October 2022 to study the complex interactions of aerosols, clouds and air pollution in the coastal urban environment. As part of the Tracking Aerosol Convection interactions Experiment (TRACER), the TRACER- Air Quality (TAQ) campaign the Experiment of Sea Breeze Convection, Aerosols, Precipitation and Environment (ESCAPE) and the Convective Cloud Urban Boundary Layer Experiment (CUBE), a combination of ground-based supersites and mobile laboratories, shipborne measurements and aircraft-based instrumentation were deployed. These diverse platforms collected high-resolution data to characterize the aerosol microphysics and chemistry, cloud and precipitation micro- and macro-physical properties, environmental thermodynamics and air quality-relevant constituents that are being used in follow-on analysis and modeling activities. We present the overall deployment setups, a summary of the campaign conditions and a sampling of early research results related to: (a) aerosol precursors in the urban environment, (b) influences of local meteorology on air pollution, (c) detailed observations of the sea breeze circulation, (d) retrieved supersaturation in convective updrafts, (e) characterizing the convective updraft lifecycle, (f) variability in lightning characteristics of convective storms and (g) urban influences on surface energy fluxes. The work concludes with discussion of future research activities highlighted by the TRACER model-intercomparison project to explore the representation of aerosol-convective interactions in high-resolution simulations.

  PublisherDOI

Recent grants

• Collaborative Research: Processes that Regulate Vertical Accelerations in Supercell Updrafts

  NSF · $438k · 2019–2024

• The Dynamical Influences of Low-Level Shear and Lifting Condensation Level on Supercell Tornadoes

  NSF · $437k · 2015–2019

Frequent coauthors

• John M. Peters

  Pennsylvania State University

  12 shared

• Hugh Morrison

  NSF National Center for Atmospheric Research

  8 shared

• Jake P. Mulholland

  University of North Dakota

  7 shared

• Milind Sharma

  5 shared

• Anita D. Rapp

  Texas A&M University

  5 shared

• Brianna H. Matthews

  Texas A&M University

  5 shared

• Sarah D. Brooks

  Texas A&M University

  5 shared

• Oliver W. Frauenfeld

  5 shared

Labs

• Atmospheric Sciences Research Group, Texas A&M UniversityPI