CCC group research falls within three topic areas of atmospheric science: Radar & Satellite Meteorology, Upper Troposphere and Lower Stratosphere (UTLS) studies, and Climate Variability and Change. Many of the topics that we work on are cross-cutting in that they require and contribute to knowledge in more than one of these areas. For example, thunderstorms are capable of reaching the tropopause: the boundary between the lowest layer of the atmosphere and that in which we live (the troposphere) and the layer immediately above (the stratosphere). If a storm overshoots the tropopause and extends into the stratosphere, it may lead to transport of air between the two layers (stratosphere-troposphere exchange or STE). STE affects the composition of the UTLS, which in turn leads to changes in the radiation budget and climate. Studying such problems enables the CCC group to broadly impact the atmospheric sciences. Additional details on our research activities and research identity can be found below.
CCC group research is/has been previously supported by the National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), and the National Oceanic and Atmospheric Administration (NOAA).
Radar & Satellite Meteorology
Weather radars are able to detect cloud and precipitation particles suspended in the air and their motion toward and away from the radar at fine spatial and temporal resolution. Modern systems that transmit both horizontally and vertically polarized beams (polarimetric or dual-polarization radars), such as the recently upgraded NEXRAD WSR-88D network in the United States, provide information on the size, shape, phase (liquid or ice), and concentration of these particles. As a result, these radar observations enable studies on the physical and dynamical characteristics of storms. On the other hand, satellite observations (especially imagery from geostationary platforms) can be combined with radar to provide broader context in cloudy and cloud-free situations and allow for unique cloud top studies that are not possible from radar. CCC group activities in these areas are largely focused on:
- Development of three-dimensional large-area, high-resolution mergers (or composites) of volumes from individual NEXRAD WSR-88D radars, which we call GridRad data (GridRad.org). For years 2013-Present, we have been incorporating all available polarimetric variables. For years 2011-Present, we have been experimenting with several dynamical variables.
- Using GridRad data to study tropopause-overshooting storms and their transport potential.
- Combining GridRad data and high-resolution (≤ 1 min) satellite imagery to study severe and/or tropopause-overshooting storms. An important phenomenon we focus on here is the above-anvil cirrus plume.
- Development of machine learning models to characterize and predict storm types and hazards in vast radar and satellite datasets.
- Using polarimetric GridRad data and single-radar data to determine the bulk microphysics of storms.
- Validation of numerical model (e.g., WRF) simulations of storms and their characteristics using GridRad data.
Upper Troposphere and Lower Stratosphere (UTLS) Studies
Because the chemical characteristics of the troposphere and stratosphere are distinctly different, interactions between the two such as STE can significantly impact the composition of the UTLS and the structure of the tropopause. Moreover, since these interactions involve greenhouse gases, they directly impact the radiation budget and climate. For example, the primary research interest for STE studies is typically the irreversible modification of greenhouse gases such as LS water vapor (troposphere-to-stratosphere transport) or UT ozone (stratosphere-to-troposphere transport). Thunderstorms, though widely studied for their meteorological impacts, are increasingly becoming a focal point of UTLS studies and the CCC group is helping to lead the community in this area. CCC group activities for UTLS research include:
- Observational studies of STE and its impact on UTLS composition and chemistry. A majority of our efforts are focused on midlatitude storms using aircraft, satellite, and radar observations.
- Climatological studies of large-scale STE processes using global winds from model analyses to drive a trajectory model.
- Numerical modeling of thunderstorms. These efforts support process- (or mechanism) based studies of STE and evaluation of the quantitative impacts of storms on UTLS composition.
- Tropopause identification, classification, and evolution.
- Development of machine learning models to identify signatures of STE and other processes affecting UTLS composition from large satellite and aircraft datasets.
Climate Variability and Change
CCC group research leverages our strengths in radar and satellite meteorology and UTLS studies to address problems related to climate variability and change. As the Earth warms in response to increasing concentrations of greenhouse gases from human activity, the global circulation, associated precipitation patterns, and storm characteristics and/or their frequency may change. In order to assess these changes, we need to establish a thorough understanding of processes in the current climate and develop appropriate methods to evaluate those processes within representations of the future climate from numerical models. Our approach in this area is to use the full 3-D output from global climate models and modern reanalyses to address scientific questions relevant to our ongoing work in other areas. Many of these activities are completed through collaboration with Drs. Elinor Martin and Jason Furtado at the University of Oklahoma. CCC group activities focused on climate include:
- Measuring the width of the tropics in past and future climates using tropopause-based metrics.
- Assessing past and future changes in characteristics of the tropopause.
- Storm modes, extreme precipitation, and severe weather in past and future climates.
- STE and the composition of the UTLS in past and future climates.
Current & Previous Collaborative Relationships, Projects and Field Experiments
- NSF AI Institute for Research on Trustworthy AI in Weather, Climate, and Coastal Oceanography (AI2ES), 2020-2025
- Dynamics and Chemistry of the Summer Stratosphere (DCOTSS), 2019-2023
- Prediction of Rainfall Extremes at Subseasonal to Seasonal Periods (PRES2iP), 2017-2021
- OU Intelligent Aerospace Radar Team (IART), 2016-Present
- SPARC-Reanalysis Intercomparison Project (S-RIP), 2013-2019
- CONvective TRansport of Active Species in the Tropics (CONTRAST), January-February 2014
- Airborne Tropical TRopopause EXperiment (ATTREX), January-March 2013 & 2014
- Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS), August-September 2013
- Deep Convective Clouds & Chemistry experiment (DC3), May-June 2012
- Stratosphere-Troposphere Analyses of Regional Transport 2008 (START08), April-June 2008