Kelly Ryan (Co-I) and Heather Holbach (Co-I)

Sim Aberson, Joe Cione, Jun Zhang

Small features in the eyes and eyewalls of very intense tropical cyclones have been hypothesized to increase the amount of energy available for hurricane intensification, or to be responsible for damaging surface wind at landfall or intense turbulence features impacting flight operations. However, the structures of these features, especially the temperature and humidity structures, have never been documented.

Jun Zhang (PI) and David Nolan (co-PI, UM)

Tropical cyclone (TC) convection produces gravity waves that propagate both upward and outward. The observational data collected from this module will be analyzed to quantify the characteristics of the gravity waves in mature-stage hurricanes and their relationship with storm intensity and intensity change. These data would also provide valuable information for model evaluation and physics improvement.

Paul Chang (PI), Zorana Jelenak, Joe Sapp, and Suleiman Alsweiss (NOAA/NESDIS/STAR); Heather Holbach (HRD PI)

Lev Looney, Ron Dobosy (NOAA/ARL-ret), Altug Aksoy, Sim Aberson, Frank Marks, Kelly Ryan, Brittany Dahl, David Richter (Notre Dame), Michael Bell (CSU), Don Lenschow (NCAR), George Bryan (NCAR), Josh Alland (NCAR), Rosimar Rios- Berrios (NCAR), Chris Rozoff (NCAR), Eric Hendricks (NCAR), Falko Judt (NCAR), Jonathan Vigh (NCAR), Xiaomin Chen (UAH), Johna Rudzin-Schwing (MS State), Zhien Wang (SBU)

This experiment will leverage NOAA’s P-3 aircraft to deploy uncrewed assets into regions of the TC environment that are unsafe for crewed operations. The experimental goals are to collect detailed observations that will improve the physical understanding of hurricane structures, enhance real-time situational awareness, and, ultimately, lead to better operational forecasts of TC track and intensity. It is believed that observations from these unique platforms will improve basic understanding and enhance forecaster situational awareness. Detailed analyses of data collected from these small drones also have the potential to improve the physics of computer models that predict changes in storm intensity.

Paul Reasor and John Gamache

Three-dimensional wind analyses derived from two P-3 aircraft equipped with tail-Doppler radar (TDR) and flying simultaneous, perpendicular transects through the hurricane eyewall are compared in an evaluation of the Doppler-radar wind analysis method. Through this evaluation, we seek to gain a better understanding of how to relate radar-derived peak wind speed and other aspects of hurricane wind structure to similar estimates using conventional observations.

Brian Tang (UAlbany), Trey Alvey, Jun Zhang, Kristen Corbosiero (UAlbany)

Ventilation occurs when drier and/or cooler environmental air intrudes into a vertically-sheared, tilted tropical cyclone (TC). Ventilation pathways include lateral intrusion (radial ventilation) and downward intrusion (downdraft ventilation) of dry and/or cool air. Both pathways may inhibit intensification. This module aims to collect observational data to study ventilation pathways, validate model simulations of ventilation in TCs, and assess the link between ventilation and intensity changes.

Heather Holbach, John Kaplan, Jun Zhang, Ghassan Alaka, Frank Marks, Lew Gramer, Lev Looney, George Alvey, Forrest Masters (University of Florida), Brian Phillips (University of Florida), Michael Biggerstaff (University of Oklahoma), David Nolan (University of Miami), Xiaomin Chen (University of Alabama Huntsville), Johna Rudzin (Mississippi State University), John Schroeder (Texas Tech University)

Landfalling tropical cyclones (TCs) often produce a variety of high impact weather over land including tornadoes and damaging winds (particularly gusts) for which there exists limited objective forecast guidance. Thus, our experiment seeks to utilize P-3 aircraft, land-based mobile research team instrumentation, and ocean-based uncrewed surface vehicles to collect data in landfalling TCs to improve both our understanding and capability to predict the dangerous phenomena often associated with these landfalling systems.

Tropical cyclones can either decay (spin down) or transform into powerful extratropical cyclones when they encounter cold water below or high wind shear in the atmosphere. The mechanisms by which tropical cyclones become extratropical is not well forecast by numerical models leading to large errors, especially in impacts downstream of the actual transitioning cyclone. This experiment aims to improve forecasts of these systems.

CHAOS presents a coordinated multi-platform, multi-institutional approach utilizing a diverse suite of innovative observing platforms (i.e., autonomous, uncrewed, expendable) and conventional ones (e.g., aircraft) focused on:

● Targeted coordinated observations of the air-sea transition zone, including the open ocean and coastal regions, to improve the understanding of air-sea interactions before, during, and after tropical cyclone (TC) passage for improved prediction and modeling

● Coordinated atmospheric and oceanic observations with sustained monitoring of key ocean features – e.g., major ocean currents, oceanic eddies and rings, and freshwater barrier layers.

Jun Zhang (PI, HRD/CIMAS), Nick Shay (Co-PI, UM), Elizabeth Sanabia (Co-PI, UW), Benjamin Jaimes (Co-PI, UM), Sue Chen (NRL), Joseph Cione (AOML), Cheyenne Stienbarger (GOMO), Lev Looney (CIMAS), David Richter (UND), Michael Bell (CSU), Steven Jayne (WHOI), Joshua Wadler (ERAU), James Doyle (NRL), Gregory Foltz (AOML), Xuejin Zhang (AOML) Guo Lin (CIMAS), Heather Holbach (FSU/NGI), Martha Schonau (Scripps), Luca Centurioni (Scripps), Theresa Paluszkiewicz (OOC, LLC), Bia Villas Bôas (MINES), Henry Potter (TAMU), Paul Chang (NESDIS)

Physical representation of how the atmosphere and ocean interact in numerical forecast models of tropical cyclones (TCs) have not been fully evaluated against observations. Near collocated and simultaneous measurements of the ocean and the atmosphere just above the ocean surface, the energy exchanges that occur between them, and how they change over time have been less understood due to lack of substantial close coordination across a wide array of ocean and atmosphere observing platforms. This experiment will provide a unique opportunity to evaluate how well coupled forecast models represent these lowest regions of storms. The new type of observations that are collected should help improve the model initialization and inform how coupled forecast models represent interactions between the ocean and atmosphere in hurricanes.

David Richter (PI, University of Notre Dame), Michael Bell (Co-PI, Colorado State University), Jason Dunion (Co-PI), Jun Zhang (Co-PI), Bia Villas Bôas (Colorado School of Mines), Elizabeth Sanabia (University of Washington, Applied Physics Laboratory), Steven Jayne (Woods Hole Oceanographic Institution), Henry Potter (Texas A&M University), Johna Rudzin (Mississippi State University)

The exchange of momentum, heat, and moisture between the ocean and atmosphere plays a central role in the presence, timing, location, and severity of extreme weather events including tropical cyclones (TCs). The experiment aims to improve our understanding and parameterization of air-sea interaction by focusing on two central elements: waves and turbulence in the TC environment. This experiment uses state-of-the art measurement and modeling platforms, while at the same time unlocking the potential of existing databases through progress in theoretical understanding. The observational work centers on co-located measurements of ocean, wave, and turbulence properties simultaneously.

This experiment seeks to use aircraft observations to better validate high-resolution surface wind speed measurements becoming more frequently available with Synthetic Aperture Radar (SAR) polar orbiting passes. This will be accomplished by coordinating NOAA P-3 flights to occur simultaneously with an orbiting SAR pass near a TC or other ocean environments deemed research relevant to sample the wind and wave interface near the surface.

Brittany Dahl (co-PI), Jason Dunion (co-PI), Trey Alvey (co-PI), William Blackwell (MIT, Lincoln Laboratory), Patrick Duran (NASA MSFC SPoRT)

This experiment is designed to calibrate and validate temperature, moisture, and precipitation measurements obtained from the new TROPICS satellites. These profiles will be compared to NOAA P-3 and G-IV aircraft observations, whose flight patterns will be coordinated in space and time with overpasses from the satellite.