Announcing a new publication in the American Geophysical Union's "Geophysical Research Letters" (GRL) journal! The paper is led by Michael Kopelman, currently a 1st-year Master's student at Florida State University. It is the culmination of Michael's undergraduate research, which he started as a freshman working with Prof. Allison Wing and I. You can find the paper here.
We use 26 years of dropsondes from the Hurricane Hunters to look at the structure of moist static energy (MSE) around Atlantic tropical cyclones (TCs). MSE is a metric combining contributions from temperature, moisture, and gravitational potential energy. In past modeling studies, MSE has been useful for diagnosing TC intensity, intensity change, and processes influencing these such as radiative heating from clouds. Since dropsondes provide detailed vertical samples of temperature, pressure, humidity, and wind, we have a possible pathway to characterizing these processes in real, observed TCs for the first time.
Combined profile of moist static energy from all dropsondes released into Hurricane Jerry (2019).
Michael found that MSE tends to vary more between the TC's inner core and outer environment in hurricanes, compared to tropical storms. He also found that MSE tends to be larger throughout the TC environment in storms that rapidly intensify in the 24 hours after a dropsonde is launched. In other words, MSE may be a useful predictor of future hurricane intensity change! Michael performed additional analysis that you can find in the paper and its Supporting Information, including decompositions of MSE into its temperature and moisture terms, how MSE varies around the storm circulation, and how the spatial structure of MSE varies at different stages of a storm's life cycle. His work has essentially produced one of the most extensive climatologies of thermodynamic structure in Atlantic TCs to date.
Figure 2 from Michael's paper. The top row shows the spatial structure of MSE in tropical storms, followed by differences between hurricanes and tropical storms. Rows below break MSE down into anomalies (differences from the mean), then its individual contributions from moisture and temperature.
Based on Michael's work, we largely repeat a series of recommendations initially made from my 2022 modeling study for planning a Hurricane Hunter mission aimed at sampling MSE structure with limited dropsondes to deploy.
Use upper-level reconnaissance (i.e. the G-IV aircraft), as important features exist above the level flown by the Air Force and NOAA P-3 planes.
Approach the center of the storm as closely as safely possible. This can be tricky, so in a perfect world, we'd do this with aircraft that fly above the storm's deep convection and outflow! But studies have shown that processes like cloud-radiation feedback are especially important early in a storm's life cycle, so getting close might be more manageable.
Sample all quadrants of the storm, and deploy dropsondes at a wide range of different radii. A star-shaped pattern is likely the most efficient for this purpose.
Hypothetical Hurricane Hunter reconnaissance flight paths overlaid on the MSE field of a simulated hurricane, from my 2022 study in GRL.
A goal for this is to motivate more "process-oriented" studies of observed TCs. Michael is working on this now, blending this thermodynamic TC climatology with satellite observations of radiation. Meanwhile, I am interested in how wind shear ties into all of this, and have been brainstorming ideas on how to approach this question with observations and models. Have questions or comments? Drop me an email at jacob.carstens@und.edu, or connect with me via linktr.ee/jcarstens, and let's chat!
This work was supported by NASA and NOAA grants, whose information can be found in the paper. Huge shoutout to those who have helped at various stages of the work, including support on the data side from various NOAA partners (including Jonathan Zawislak, Sim Aberson, and Jason Dunion), academic collaborators (including Morgan O'Neill and Dan Chavas), and Florida State's Undergraduate Research Opportunity Program (UROP) and Honors in the Major undergraduate thesis program.
Comments