Statement of Research and Teaching Interests. Beate G. Liepert

Transcription

1 April, 2007 Statement of Research and Teaching Interests Beate G. Liepert Educational and Professional Background My general research goal and interests are the understanding of natural and anthropogenic climate variations from seasonal to centennial time scales. In particular, I study the water and energy cycles, which interact with the land, atmosphere and ocean sub-systems of the Earth. My special expertise is in atmospheric physics, which I analyze theoretically and experimentally. I graduated from the University of Munich at the Institute of Meteorology, Physics Department. My research interests were influenced by this Institute and its renowned history that lists scientists like R. Geiger (Koeppen/Geiger classification of climates), F. Moeller (atmospheric radiation), and by mentors like A. Baumgartner ("Global Hydrological Atlas"), P. Fabian (atmospheric chemistry) and atmospheric dynamics J. Egger. After graduating, I became a postdoctoral researcher at the Lamont-Doherty Earth Observatory of Columbia University and then a Doherty research scientist in the same institution. I collaborate closely with the NASA Goddard Institute for Space Studies that houses the Department of Applied Physics and Mathematics of Columbia University. In 2002, I spent a year as visiting scientist at the Max-Planck Institute for Meteorology in Hamburg Germany as guest of Hans Feichter in the aerosol climate modeling group. I still collaborate and publish with Hans. At NASA-GISS and MPIfMet I worked with general circulation models and satellite products like the ISCCP cloud project. I visited the CERES team at NASA Langley Research Center for several months in This visit provided me with information and skills necessary to perform research with ERBE and CERES satellite data. In more recent years I began advising and mentoring students and a postdoc. I organized my own field campaigns and started collaborating with ecosystem scientists at Lamont. Over the years, public outreach in form of media interviews and public lectures and panels became more dominant in my professional life. Past Research Accomplishments and Research Statement In my opinion my major scientific accomplishment in climate research so far is my leading role in discovering and studying the changes of surface solar radiation during the second half of the last century. This phenomena was later coined "global dimming" in the general press. My research on this subject includes one of the first data analyses of time series of solar radiation worldwide, investigations of the causes of the observed reductions, particularly the different roles of anthropogenic aerosols and greenhouse gas (GHG) forcing, and analyses of cloud 1

2 feedbacks and aerosol indirect effects on clouds (Liepert, 2002). I studied possible global climatic effects of anthropogenic aerosols in the context of multi-decadal changes in solar fluxes, especially consequences for the global water cycle. One finding of my research is the challenge of the common assumption of an intensified water cycle in a warmer world. In Liepert et al. (2004) we show that aerosol direct and indirect effects on clouds and cloud and water vapor feedbacks of greenhouse gas warming tend to reduce solar radiation at the surface such that evaporation is suppressed in a warmer world. Reduced evaporation leads to reduced globally averaged precipitation. Hence the water cycle can be suppressed in a global warming scenario if aerosol direct and indirect effects are included in a GHG scenario. My first scientific findings from my masters thesis are cited in the IPCC Scientific Report 1996 (Liepert, Fabian, Grassl, 1994). As a postdoc researcher at Lamont I developed a statistical model for separating cloud and aerosol effects that helped quantifying the causes of the observed reductions in solar radiation in the United States (Liepert, 1997). Climatological aerosol and cloud data are not available or very sparse and models are needed to understand physical processes. In the course of the years, I worked in close collaborations with several climatemodeling groups and studied the effects of anthropogenic aerosols and greenhouse gas forcing on the surface energy budget. M. Wild and I reported of significant deficiencies in the shortwave flux calculations of atmospheric GCMs due to neglected aerosol concentrations (Wild/Liepert, 1998). In another study in collaboration with U. Lohmann I argue that excessive transmission of solar radiation causes excessive drying of continental land in summer in climate models (Liepert/Lohmann, 2001). In Liepert and Tegen (2002) we conclude that carbonaceous aerosols are underestimated while reflecting sulfate aerosols tend to be overestimated in emission scenarios used in climate models. These results support J. Hansen's arguments of the importance of absorbing aerosols in the global warming debate. The study on "the spin down of the water cycle in a warmer and moister world" (Liepert et al. 2004) was performed during a one year visit to the Max-Planck Institute for Meteorology in Hamburg. The combined impact of anthropogenic greenhouse gases and aerosols on climate was simulated with ECHAM - GCM experiments. Regionally inhomogenous changes in solar radiation effect the atmospheric dynamics and regional transport of moisture quite differently. For example, the dynamical effects of aerosols on the monsoon system are still unknown and widely debated. I am currently working on this issue in collaboration with A. Giannini. Studying these processes will be key in understanding anthropogenic impact on the water cycle. Feedback processes of clouds and water vapor are also important subject in my research. The use the new generation of satellite sensors like CERES and MODIS and its products in combination with models will help answer key questions in the water and energy cycle of the Earth System. Hence T. Charlock invited me to visit and collaborate with the CERES team at NASA Langley Research Center. Together with N. Romanou I evaluated surface solar flux changes simulated in transient runs of the 20 th century of several coupled-atmosphere-ocean GCMs and satellite based estimates. We conclude that all models calculate a 20 th century dimming which levels off in the last two decades. The effects of 2

3 Pinatubo on surface solar radiation and its recovery in the early 1990s together with the pronounced ENSO signal in the spatial changes of cloud coverage causes short-term variability. This project was funded for the 4th Assessment Report of the IPCC. I am a contributing author to IPCC working group 1 Scientific Basis chapter 3 Observations: Surface and Atmospheric Climate Change. On a local scale, I performed field experiments where we determined effects of aerosols from local sources versus the large-scale transport. My students measured the optical properties of aerosols in New York City, on the Hudson River around Manhattan and aboard a hot-air balloon in the Metropolitan region. I am currently writing on manuscripts that will summarize and interpret these experiments as regional contributions to the global aerosol problem. Linking local observations with global analysis is an important challenge for aerosol and cloud research. Also, I am collaborating with plant physiologists and started studying the effect of aerosols on scattered and direct sunlight and therefore on plant photosynthesis. My research interest in the energy and water cycle bridges local and global scales and links subsystems of the Earth by studying their dynamical interactions. Collaborating in multidisciplinary groups of scientists is familiar to me and essential for answering complex climate system questions that cannot be studied in one subsystem alone (See my co-authored paper on the divergence problem of tree-ring reconstruction D Arrigo et al 2007). Also analyzing the predominant role of clouds and cloud feedbacks on climate will be a key challenge in my future research (Gorodetskaya etal., 2007). Community Service Several of my studies were widely published in the general press and had a broader impact beyond my field (New York Times, Time magazine, CNN, Scientific America etc.). Perhaps my most important research initiative was the idea and planning of the special session on "Global Dimming" that I organized for the joint AGU / CGU Assembly in Montreal in Spring of It was the first worldwide gathering of a multi-disciplinary group of scientists from astronomers, engineers, and meteorologists to plant physiologists who presented evidence of changes in surface solar radiation on a decadal time-scale (Cohen et al., 2004). The session motivated new research initiatives by NASA and NOAA scientists (re-examination of satellite surface products and ground observations) and stimulated controversial debates among experts in the community. I am contributing author for Chapter 3 of the IPCC Fourth Assessment Report (AR4) of Working Group 1. The European community nominated me to serve as an international expert on the evaluation panel for the European Community 6TH Research Framework Programme topic priority "Global change and Ecosystems". I also participated in the BBC London produced documentary on global dimming. I regularly review manuscripts for major scientific journals and proposals for U.S. and European funding agencies. Furthermore, I take part in University 3

4 activities like open house and summer programs and I am a member of the Executive Committee of Lamont Observatory, the governing body of the institute. Past Teaching Initiatives I gained my first teaching experience as a teaching assistant at the Meteorological Institute in Munich. As a graduate student in Munich, I developed the idea of students meetings from various faculties and organized a multidisciplinary workshop in the Bavarian Forest for graduate students with the topic "Climate change and its consequences for the Alps". At Lamont I organized a seminar series where graduate students and postdocs could practice their presentations prior to scientific conferences. Lecturing and mentoring has always been a pleasure for me. I advise senior thesis projects and serve on a PhD committee. I also mentor summer intern students and research assistants on a regular basis. Personally most rewarding for me was the mentoring of several high school students during two summers for the NASA-GISS summer program "Institute for Planets and Climate". This program is aimed at underprivileged minority students from public high schools in New York City. Overcoming their perceptions and stereotypes of scientists and overcoming my perceptions and stereotypes of inner-city high school students was most challenging and rewarding. Therefore, I will pursue mentoring and teaching also with the goal of supporting underrepresented groups. I taught the introductory and atmospheric part of an undergraduate course in Earth System Science at Department of Earth and Environmental Sciences at Columbia University. I was engaged in outreach programs of Medgar Everts Community College in Brooklyn, New York, give public lectures for open house, and fund-raising events, and serve on public panels that discuss climate change issues. Teaching Statements My own experience as a student can be described as a professor in front of a blackboard who lecturers to the class. This frontal style did not lead to immediate insight and pleasure in learning. I gained real insight only by working on assignments and particularly as an internship at the world renowned Observatory Hohenpeissenberg. Based on this experience, I believe that students succeed best in science if lecturing is complimented with direct research experience. For example, I involve my undergraduate students in all states of a research project. My undergraduate students work with me from the beginning of a project (proof of concept studies) to the final presentation of the work. They witness failure of ideas as much as success of ideas and learn how a scientific question becomes a science project. It helps them to develop critical scientific thinking and it trains the ability to see new paths, to deal with frustrations and to focus their work into a successful project. For example, the undergraduate student Peggy Hannon joined me as a summer intern. She continues her research and writes her senior thesis on the subject of the summer. She was featured on the Lamont webpage. At the end of the year Peggy presented her poster at the AGU Fall meeting in San Francisco. 4

5 Students who enroll in Earth sciences usually have various backgrounds and knowledge in mathematics, physics, biology, chemistry etc. Students in traditional Earth science departments specialize in one field and learn to focus on one aspect or subsystem of the Earth system. For example, atmospheric physicists concentrate on the atmosphere and may learn some principles of ocean sciences but rarely gain knowledge of the fundamental questions within the other subsystems. In Earth system sciences, however, it is essential to understand the boundaries and interactions between one subsystem and the adjacent subsystems. It is important for the student to understand what the systems' interactions and what the key processes are within the other subsystems. For example, solar radiation is important for atmospheric dynamics but also a key parameter in the biosphere (photosynthesis). Hence, I would propose to teach courses in my fields of expertise in atmospheric physics but with a strong component that focuses on land ocean atmosphere - interactions. A second level of courses could concentrate on key issues of the entire Earth system, like energy and water cycles. The energy and water cycles affect processes in all subsystems. Therefore this subject teaches the students the importance of gaining a complete overview on the Earth System. Other cycles exist and can be taught collaboratively (carbon cycle). Also, in my opinion, it seems important for the student to learn that certain scientific tools can be utilized in a variety of different ways in the Earth system sciences. Building awareness in the classroom of the multidisciplinary application of such tools like thermodynamics will help the students develop a multidisciplinary background and foster creativity in their scientific approach. In summary, in my opinion, the exciting opportunities of Earth System Sciences should aim to broaden the thinking of students without loosing the in depths skills of the individual fields. Developing a program of Earth System Sciences at McGill University is a great opportunity and I would love to participate. 5