Ph.D. Research
"Extratropical Cyclones leading to Extreme Weather Events over Central and Eastern North America"
Cool-season extreme weather events (EWEs) occurring over central and eastern North America are typically associated with strong extratropical cyclones (ECs) that are governed by varying combinations of baroclinic, diabatic, and barotropic processes.  The opportunity to investigate the ways in which baroclinic, diabatic, and barotropic processes evolve and combine to produce ECs leading to EWEs motivates this study.  A 1979–2016 climatology of ECs leading to EWEs over central and eastern North America constructed using the 0.5° NCEP Climate Forecast System Reanalysis reveals that ECs leading to EWEs typically form:  1) in the lee of the Rocky Mountains, 2) over the south central United States, and 3) along the east coast of North America.  Metrics representing baroclinic, diabatic, and barotropic processes are calculated as regional averages of their corresponding Lorenz (1955) energy generation and conversion terms during the evolution of ECs included in the 1979–2016 climatology.  These metrics reveal that contributions from baroclinic, diabatic, and barotropic processes are significantly larger during the evolution of ECs leading to EWEs than during the evolution of ordinary ECs.

Research support provided by NSF Grant AGS-1355960

                       


M.S. Research
"Upper-Tropospheric Precursors Associated with Subtropical Cyclone Formation in the North Atlantic Basin"
 This study investigates the roles of baroclinic and diabatic processes during the evolution of subtropical cyclones (STCs) by calculating three potential vorticity (PV) metrics from the 0.5° NCEP CFSR dataset.  The three PV metrics quantify the relative contributions of lower-tropospheric baroclinic processes, midtropospheric diabatic heating, and upper-tropospheric dynamical processes during the evolution of individual cyclones.  Quantification of these three contributions reveals the changing PV structure of an individual cyclone, indicates fluctuations in the dominant energy source of the cyclone, and aids in categorizing the cyclone.
Research support provided by NSF Grant AGS-0935830                  

Publications

Bolinger, R. A., V. M. Brown, C. M. Fuhrmann, K. L. Gleason, T. A. Joyner, B. D. Keim, A. Lewis, J. W. Nielsen-Gammon, C. J. Stiles, W. Tollefson, H. E. Attard, and A. M. Bentley, 2022: An assessment of the extremes and impacts of the February 2021 south-central U.S. arctic outbreak, and how climate services can help. Wea. and Climate Extremes, 36, 100461, https://doi.org/10.1016/j.wace.2022.100461.


Bentley, A. M., L. F. Bosart, and D. Keyser, 2019: A climatology of extratropical cyclones leading to extreme weather events over central and eastern North America. Mon. Wea. Rev., 147, 1471-1490, https://doi.org/10.1175/MWR-D-18-0453.1.


Bentley, A. M., L. F. Bosart, and D. Keyser, 2017: Upper-tropospheric precursors to the formation of subtropical cyclones that undergo tropical transition in the North Atlantic basin. Mon. Wea. Rev., 145, 503-520, https://doi.org/10.1175/MWR-D-16-0263.1.


Bentley, A. M., D. Keyser, and L. F. Bosart, 2016: A dynamically based climatology of subtropical cyclones that undergo tropical transition in the North Atlantic basin. Mon. Wea. Rev., 144, 2049-2068, https://doi.org/10.1175/MWR-D-15-0251.1.

 

Bentley, A. M., and N. D. Metz, 2016: Tropical transition of an unnamed, high-latitude, tropical cyclone over the eastern North Pacific. Mon. Wea. Rev., 144, 713-736, https://doi.org/10.1175/MWR-D-15-0213.1.

 

Laird, N., A. M. Bentley, S. Ganetis, A. Stieneke, and S. A. Tushaus, 2016: Climatology of lake-effect precipitation events over Lake Tahoe and Pyramid Lake. J. Appl. Meteor. Climatol., 55, 297-312, https://doi.org/10.1175/JAMC-D-14-0230.1.


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