Diana Thatcher


Email:

diana.r.thatcher@gmail.com

Office:

SRB 2133

 

Current Status:

PhD Candidate (4th Year)

 

Curriculum Vitae

Research Interests
  • Climate model dynamical cores for atmospheric simulations
  • Idealized test cases for dynamical cores
  • Short-term forecasting with high-resolution GCMs
  • Variable resolution tropical cyclone models
  • Extratropical transition of tropical cyclones
Exploring physics-dynamics coupling with a moist idealized test case
The new moist idealized test case uses simplified moist physical parameterizations and is a valuable tool for understanding complex interactions within general circulation models, such as the coupling between the dynamical core and the physical parameterizations.

Full physical parameterizations can mask undesirable features in the model and are expensive. Dry dynamical core test cases are a common way to inexpensively test the dynamical core, but cannot provide insight into the non-linear physics-dynamics moisture feedbacks. The moist idealized test case is an inexpensive test of intermediate complexity that can be used to investigate various phenomena.

For example, this plot shows an instantaneous snapshot of vertical pressure velocity on the 850 hPa pressure level (left) and precipitation rate (right) for two different physics-dynamics coupling mechanisms. For se_ftype = 1 (bottom), the updates from the physical parameterizations are applied to the dynamical core in a single timestep. The bottom panels show that this leads to spurious gravity waves eminating from regions of intense rainfall.

These spurious gravity waves are only seen in the presence of moisture. They are often overlooked in climate simulations because the results are typically plotted using long-term averages instead of the instantaneous snapshot shown here. The problem is solved by using the updated setting, se_type = 0 (top), which applies the updates from the physical parameterizations over multiple dynamics time steps. This avoids sudden changes to the dynamical system and prevents spurious gravity waves, as seen in the top panels.

Extratropical transition of tropical cyclones
Extratropical transition occurs when a tropical cyclone gradually transforms into an extratropical cyclone. Tropical cyclones have a warm-core structure and are symmetric about the eye, while extratropical cyclones have a cold-core structure and are asymmetric.

To correctly simulate this process, CAM-SE must simulate the convective processes within tropical cyclones, the dynamics governing synoptic-scale flows, and the interactions between the tropical cyclone and the surrounding environment. CAM-SE successfully models the extratropical transition of tropical cyclones, including the position, duration, seasonal cycle, and multidecadal climatology of extratropical transition in the North Atlantic basin.

The right panel shows a tropical cyclone in CAM-SE intensifying into a Category 4 hurricane as it travels toward the East Coast. The extratropical transition takes 36 hours and occurs as the cyclone travels northward. The extratropical cyclone gradually dissipates as it travels westward across the North Atlantic Ocean.

The left panel shows the cyclone phase space diagram. The top panel shows the cyclone developing a warm core in the lower troposphere (larger values for -vTL), gradually becoming less symmetric about the eye of the storm (larger values for B), then finally losing the warm core structure in the lower troposphere (smaller values for -vTL). The bottom panel shows the cyclone developing strong warm-core structures in the upper and lower troposphere (larger values for -vTL and -vTU), then gradually transitioning to cold-core structures as the storm develops into an extratropical cyclone (smaller values for -vTL and -vTU).

Journal Articles
  • Gross, M., D. Williamson, H. Wan, P. Caldwell, D. Klocke, C. Jablonowski, D. R. Thatcher, N. Wood, M. Cullen, R. Beare, M. Willett, F. Lemarié, E. Blayo, S. Malardel, P. Termonia, P. Bechtold, A. Gassmann, P. H. Lauritzen, H. Johansen, C. M. Zarzycki, K. Sakaguchi, and R. Leung, (2015) "Physics dynamics coupling in geophysical models." In preparation.
  • Thatcher, D. R., C. M. Zarzycki, and C. Jablonowski (2015) "Multidecadal climatology of the extratropical transition of North Atlantic tropical cyclones in variable-resolution CAM5." Journal of Climate, In review.
  • Thatcher, D. R., and C. Jablonowski (2015) "A moist aquaplanet variant of the Held-Suarez test for atmospheric model dynamical cores." Geoscientific Model Development Discussions, 8, 8263-8340, doi: 10.5194/gmdd-8-8263-2015
  • Zarzycki, C. M., C. Jablonowski, D. R. Thatcher, and M. A. Taylor (2015) "Effects of localized grid refinement on the general circulation and climatology in the Community Atmosphere Model." Journal of Climate, 28, 2777-2803, doi: 10.1175/JCLI-D-14-00599.1
Presentations
  • [Talk, Animation] Thatcher, D. R., C. M. Zarzycki, and C. Jablonowski, "Extratropical transition of North Atlantic tropical cyclones in variable-resolution CAM5." CESM Workshop, Breckenridge, CO, June 2015 (talk)
  • Jablonowski, C., D. R. Thatcher, J. O. Ferguson, C. M. Zarzycki, A. Gettelman, J. Bacmeister, J. Richter, R. Neale, C. Hannay, P. Lauritzen, P. Callaghan, V. Larson, K. A. Reed, P. Ullrich, M. Wehner, M. A. Taylor, "The path forward: High-resolution next-generation CESM simulations and scale-aware physics." CESM Workshop, Breckenridge, CO, June 2015 (talk)
  • [Poster] Thatcher, D. R., C. M. Zarzycki, J. O. Ferguson, and C. Jablonowski, “Extratropical Transition Using 23 Years of Tropical Cyclones in a Variable-Resolution Global GCM.American Geophysical Union Fall Meeting, San Francisco, CA, December 2014 (poster)
  • Jablonowski, C., and D. R. Thatcher, “Physics-Dynamics Test Strategies: Bridging the Gap with Simplified Moist Test Cases.Physics Dynamics Coupling Meeting 2014, CICESE, Ensenada, Baja California, Mexico, December 2014 (talk)
  • [Poster] Thatcher, D. R., and C. Jablonowski, "Intercomparison of numerical methods in climate simulations with idealized moisture parameterizations." Michigan Institute for Computational Discovery and Engineering Fall 2014 Research Computing Symposium, Ann Arbor, MI, November 2014 (poster)
  • [Poster] Thatcher, D. R., and C. Jablonowski, “Dynamical core intercomparison using a moist variant of the Held-Suarez test case in CAM5.CESM Workshop, Breckenridge, CO, June 2014 (poster)
  • Zarzycki, C. M., C. Jablonowski, D. R. Thatcher, and M. A. Taylor, “Evaluating the impact of localized grid refinement on global climatology in CAM." CESM Workshop, Breckenridge, CO, June 2014 (talk)
  • Jablonowski, C., and D. R. Thatcher, “A Moist Variant of the Held-Suarez Test for the Assessment of Atmospheric Model Dynamical Cores.European Geosciences Union General Assembly, Vienna, Austria, April 2014 (poster)
  • [Poster] Thatcher, D. R., and C. Jablonowski, “A moist variant of the Held-Suarez test for atmospheric model dynamical cores.Workshop on Partial Differential Equations on the Sphere, Boulder, CO, April 2014 (poster)
  • Zarzycki, C. M., C. Jablonowski, and D. R. Thatcher, "The impacts of high-resolution refinement in variable-resolution CAM-SE on regional climate in CESM." CESM Atmospheric Model Working Group Meeting, Boulder, CO, February 2014 (talk)
  • [Poster] Thatcher, D. R., C. Jablonowski, and C. M. Zarzycki, “A moist idealized test case for atmospheric general circulation models: Dynamical core intercomparison.American Geophysical Union Fall Meeting, San Francisco, CA, December 2013 (poster)
  • [Poster] Thatcher, D. R., and C. Jablonowski, “Comparison of a moist idealized test case and aquaplanet simulations in an atmospheric general circulation model.University of Michigan College of Engineering Graduate Symposium, Ann Arbor, MI, November 2013 (poster)
  • [Poster] Thatcher, D. R., and C. Jablonowski, “A moist idealized test: convectively coupled equatorial waves and precipitation compared to aquaplanet simulations.Graduate Climate Conference, Woods Hole, MA, November 2013 (poster)
  • Thatcher, D. R., and C. Jablonowski, “A moist idealized test case for atmospheric general circulation models.Rackham Summer Institute Research Symposium, Ann Arbor, MI, August 2012 (talk)
  • Gilbert, J. A., S. T. Lepri, D. R. Hillinger, D. R. Thatcher, and T. H. Zurbuchen, “Singly Charged Heavy Ions Observed in Conjunction with Interplanetary Coronal Mass Ejections.American Geophysical Union Fall Meeting (Abstract SH32A-06), San Francisco, CA, December 2011 (talk)
  • Thatcher, D. R., and L. Avallone, “Distribution of Liquid Water in Orographic Mixed-Phase Clouds.Solar and Space Physics Research Experience for Undergraduates Symposium, Boulder, CO, August 2011 (talk)
  • Gilbert, J. A., S. T. Lepri, D. R. Hillinger, D. R. Thatcher, and T. H. Zurbuchen, “Contributions of coronal mass ejection plasma to the inner-source pickup ion population.Solar Heliospheric & Interplanetary Environment Conference, Snowmass Village, CO, July 2011 (poster)
  • Gilbert, J. A., S. T. Lepri, D. R. Thatcher, and T. H. Zurbuchen, “Low charge-state anomalies in the heliosphere.Slow Solar Wind TR&T Meeting, Greenbelt, MD, April 2011 (talk)
  • Thatcher, D. R., J. A. Gilbert, and S. T. Lepri, “Low Charge Ions in the Solar Wind.Undergraduate Research Opportunity Program Spring Forum, Ann Arbor, MI, April 2011 (poster)
Awards
  • Graduate Visitor Program, Advanced Study Program, National Center for Atmospheric Research
  • Michigan Institute for Computational Discovery and Engineering Fellowship, University of Michigan
  • Rackham Merit Fellowship, University of Michigan
  • James B. Angell Scholar, University of Michigan
  • Boeing Industry Scholarship
  • Regent's Merit Scholarship, University of Michigan

Latest update: 16 September 2015