Jenni L. Evans, PhD. Department of Meteorology 509 Walker Building University Park, PA 16802 Telephone: (814) 865-3240 jle7@psu.edu
Click HERE for Dr. Evans' Home Page! (Monash University, Ph.D. in Applied Mathematics), Professor  Member of Graduate Faculty  Environment Institute Faculty Professional Affiliations: American Meteorological Society American Geophysical Union Australian Meteorological and Oceanographic Society Chi Epsilon Pi Meteorological Honor Society Administrative Positions 2002/2003 University Service Department of Meteorology Faculty Search CommitteeMay 2003– Faculty Advisory Committee, International Friendship HouseJanuary 2003– College of Earth and Mineral Sciences Search Committee for the Environment Institute Director November 2002–March 2003 Department of Meteorology Strategic Planning CommitteeAugust 2001– Chair, PSU Department of Meteorology Opportunities CommitteeAugust 1999– Executive Council, Women in Science and Engineering (WISE) Institute, The Pennsylvania State UniversityJanuary 1994– Honors Student Advisor, Department of MeteorologyJanuary 1994– 2002/2003 Service for Professional Societies and Government Panels Chair, AMS Nominations Committee for President and CouncilorsJanuary 2003– Lead Meteorologist, Florida Commission on Hurricane Loss Projection Methodology Professional Team,June 2003– Chair, AMS Nominations Committee for President and CouncilorsJanuary 2003– Co-convener, Hurricane Weather and Research Forecast (WRF) Modeling Workshop, NSF Headquarters, Arlington, Virginia29-30 May 2002 Specialist Editor, Bulletin of the American Meteorological SocietyMay 2001– AMS Nominations Committee for President and CouncilorsJanuary 2001– Associate Editor, Weather and ForecastingJanuary 2001– USWRP Science Steering CommitteeJanuary 2000–

My goal is to advance our understanding of the atmosphere through teaching, research and communication of our science to the broader community. I see my role in each of these endeavors including: recruiting and educating exciting young scientists in the field and mentoring them, advancing fundamental understanding in my research areas and, where possible, making these results useful to society (perhaps via the forecasting community).

Teaching Interests: Atmospheric dynamics, fluid dynamics, numerical modeling, tropical meteorology, climate.

My background in applied mathematics – particularly, geophysical fluid dynamics – led to my interest in teaching dynamics classes at all levels. Interpretation and manipulation of the equations provides a sound basis from which to understand and forecast the atmosphere.

My love of tropical meteorology was the impetus for teaching both that class and climate modeling. Tropical storms (from thunderheads to hurricanes) have fascinated me since Cyclone Tracy devastated Darwin on Christmas Day in 1974. We can draw upon some basic concepts for understanding of the role of the tropics in the global climate system. Variations in the tropics (whether individual storms, seasonal or longer) can impact higher latitude weather, thus having implications for forecasting all around the globe.

Although I stumbled across meteorology while studying mathematics, my teaching at Penn State has inspired me to relate the equations more to weather forecasting. This drew me to teaching numerical weather prediction: numerical models are the cornerstone of modern forecasting, yet meteorologists can become formally qualified without any understanding of the complexities (and sometimes the extreme simplifications) of these models.

My teaching interests also include mentoring of independent research. Achievements of my undergraduate students include journal articles, conference presentations, AMS website contributions, development of online documentation for Navy forecasting software, Honors theses and more. I regularly offer graduate seminar courses.

Research Interests: Climate variability with particular emphasis on the tropics, tropical meteorology, numerical modeling and tropical cyclones.

The overarching question that drives my research is “What is the role of organized convection in the global climate system?” In addressing this question much of my research has been focused on (1) tropical cyclones (genesis is a focus now); and (2) tropical cyclones that undergo “extratropical transition [ET]”. These extratropically transitioning tropical cyclones move into higher latitudes, rapidly evolving into larger, damaging storm systems. Tropical cyclones derive their energy from their deep moist convection; as they undergo ET, their energy source shifts to the baroclinic development typical of midlatitude cyclones. ET storms differ from typical warm season midlatitude storms since their tropical source air greatly enhances the local temperature gradients resulting in very intense winds and large-scale flooding rains. Massive ocean waves (peak wave heights of 20+ metres) have been measured in some of these storms. More recently, the problems of classifying and forecasting (3) subtropical storms have also triggered my interest.

Other aspects of my work have included (4) satellite-derived analysis of the variability of organized convection in the global tropics on diurnal to intraseasonal timescales and reconciling these analyses with theoretical models of the tropical atmosphere; (5) exploration of global climate models: (a) potential climate change implications for tropical convection and tropical cyclones and (b) representation of the east Asian ITCZ and summer monsoon; and (6) investigation of the effect of warm and cold events on the Australasian monsoon.

The objective criteria developed by my group for the onset and completion of ET (in terms of the Cyclone Phase Space, CPS) have been enthusiastically adopted by the U.S. and Canadian National Hurricane Centers, as well as the U.S. Air Force Weather Squadron and the Joint (U.S. Navy/Air Force) Typhoon Warning Center. They are also being tested by the Japanese and Australian weather services.

Most recently, my group has begun exploring the use of cluster analysis to group storm types objectively based on their CPS structure characteristics. The goal of this research is to develop a model of storm structure evolution, using path bifurcations in the cluster transitions to help identify broader physical forcing distinctions. Key storm types expected (tropical, midlatitude, hybrid) are clearly distinguished and evolutions from one cluster to another are smooth and repeated from storm to storm. This research is in its infancy, but shows potential.

Graduate Students: I took an atypical path to graduate school, graduating from my undergraduate degree, traveling overseas, then working as a research assistant in both mechanical engineering and math (fluid dynamics) laboratories before returning to study. I encourage my graduate students to have a diversity of interests, but also expect them to have a strong commitment to their research and a clear understanding of what they hope to achieve by coming to graduate school. An interest in the tropics is desirable, but my research extends beyond this zone. I have a strong, supportive research group. We meet regularly and students are expected to present their recent results and to actively interact on each other’s research.

Evans, J. L., and R E. Hart, 2003: Objective indicators of the onset and completion of extratropical transition for Atlantic tropical cyclones. Monthly Weather Rev., 131, 909-925.

Jones, S. C., P. Harr, J. Abraham, L. F. Bosart, P. Bowyer, J. L. Evans, D. E. Hanley, B. Hanstrum, R. E. Hart, F. Lalaurette, M. R. Sinclair, R. K. Smith, and C. Thorncroft, 2003: The extratropical transition of tropical cyclones: Forecast challenges, current understanding and future directions. Weather and Forecasting, (in press).

Tsakraklides, G., and J. L. Evans, 2003: Global and regional diurnal variations of organized convection. J. Climate, 16, 1562–1572.

Chan, S., and J. L. Evans, 2002: Comparison of the structure of the ITCZ in the West Pacific during the boreal summers of 1989-1993 using AMIP simulations and ECMWF reanalysis. J. Climate, 15, 3549-3568.

Kimball, S. K., and J. L. Evans, 2002: Idealized numerical simulations of hurricane-trough interaction. Monthly Weather Review, 130, 2210-2227.

Prater-Mayes, B., and J. L. Evans, 2002: Sensitivity of modeled tropical cyclone track and structure of Hurricane Irene (1999) to the convection parameterization scheme. Meteorology and Atmospheric Physics, 80, 103-115.

Hart, R. E., and J. L. Evans, 2001: A climatology of extratropical transition of tropical cyclones in the North Atlantic. J. Climate , 14, 546-564.

Dutton, J. F. , C. J. Poulsen, and J. L. Evans, 2000: The effect of global climate change on the regions of tropical convection in CSM1. Geophysical Research Letters, 27, 3049.

King C., R. Harmon, T. Bullard, J. Evans, R. Johnson and M. Larsen, 1998: A technical analysis to identify ideal geographic locations for tropical testing of Army materiel and systems. Technical report, Environmental Systems Branch, U.S. Army Research Office, Research Triangle Park, NC, July 1998.