Xuhui Lee

Xuhui Lee

Sara Shallenberger Brown Professor of Meteorology

Professor Lee’s research and teaching concern the interactions between the terrestrial biosphere, the atmosphere and anthropogenic drivers. His areas of interest include boundary-layer meteorology, micrometeorological instrumentation, remote sensing, and carbon cycle science. One focus of his research activity is on biophysical effects of land use on the climate system. Other ongoing projects investigate greenhouse gas fluxes in the terrestrial environment (forests, cropland and lakes), isotopic tracers in the cycling of carbon dioxide and water vapor, and urban climate mitigation. His lab group deploys an array of research methodologies, including field observations (eddy covariance, optical isotope instruments, and high-precision greenhouse gas analyzers), mathematical models (land surface models, large-eddy simulation, WRF, and earth system models), and environmental remote sensing (satellites and drones). He is Sara Shallenberger Brown Professor of Meteorology, Director of the Yale Center for Earth Observation, and Program Coordinator of the Yale-Tsinghua dual degree program. He is recipient of the 2015 Award for Outstanding Achievement in Biometeorology from the American Meteorological Society. His recent textbook Fundamentals of Boundary-Layer Meteorology offers the accumulation of insights gained during his academic career as a researcher and teacher in the field of boundary-layer meteorology.

My research concerns the movement of momentum, energy, water, greenhouse gases, and air pollutants between the earth's surface and the lower atmosphere. The principles that govern such movement are drawn from several scientific disciplines including forest meteorology, boundary layer meteorology, ecosystem ecology, and atmospheric chemistry. The following is a brief summary of my current research projects.

Modeling study of land-atmosphere interactions: The objective of this project is to establish a mechanistic understanding of the interplay among air flow in the lowest portion of the atmosphere, spatial variation in land use, and fluxes of energy, water and carbon dioxide. In a typical weather and climate model, vegetation covers within a model grid are averaged to a single type and air over the grid space is treated as a one-dimensional column. This simplification may grossly underestimate the impact of biology on the atmospheric state and processes. The project will deploy a modeling methodology that couples the NCAR’s large eddy simulation model to a land surface model. It will determine biases in climate and weather prediction models when assimilating measurements taken in the presence of land surface heterogeneity.

Ecosystem-atmosphere oxygen isotopic fluxes and discrimination mechanisms: The goal of this project is to investigate processes that control the exchange of oxygen isotopes in carbon dioxide and water vapor between terrestrial vegetation and the atmosphere. Specifically, the project aims to establish a body of new knowledge on the oxygen isotope discrimination mechanisms of the whole-ecosystem photosynthesis and respiration, quantify the interplay between water and carbon dioxide isotopic exchanges at the ecosystem scale, and compare and contrast the discrimination mechanisms between C3 and C4 photosynthesis modes. The project will use soybean and corn as model systems for C3 and C4 plants. The ability to determine the ecosystem-scale oxygen isotope discrimination is essential to a number of fundamental science questions relevant to atmospheric carbon budget and ecosystem processes. In the former case, atmospheric oxygen isotopes are important tracers of carbon uptake on land. In ecosystem studies, quantification of the discrimination mechanisms can be brought to bear on the question of how to utilize atmospheric oxygen isotopes as indicators of environmental changes such as increased biospheric productivity and land use change.

CO2 emissions from forest soil during rainstorm: In this project, we use in-situ eddy covariance observation, field manipulative experiment and laboratory simulation to investigate the influence of rainstorm on soil CO2 emission. Early results from our Great Mountain forest site show that CO2 emission responds rapidly and instantaneously to the onset of rain. The pulse-like emission could amount to 5-10% of the annual net carbon sequestration by the forest in a single intensive storm. If precipitation becomes more variable in a future warmer world, the rain pulse should play an important part in the transient response of the ecosystem carbon balance to climate, particularly for ecosystems on ridge-tops with rapid water drainage.

My teaching concentrates on the applied aspects of atmospheric sciences and is structured with two different but overlapping themes. In one, I place emphasis on preparing students for professional careers by teaching skills necessary for analyzing problems arising from human interference with the atmospheric environment. In the other, I target students who are pursuing a research career.

My course portfolio adopts a pedagogy that strikes balances between basic principles and real-world experience and between structured lecture and student-led discussion. My graduate-level introductory course "Climate and Life" discusses the basic principles of meteorology and their applications in the management of natural resources and air quality. My advanced graduate course, "A Biological Perspective of Global Change" aims to promote understanding of the interface between major aspects of global change and biospheric system. In my seminar "Climate Change Science and Policy", I expose students to current debates about climate change science, adaptation and mitigation strategies.

Education

B.S.C., M.S.C., Nanjing Institute of Meteorology, China; Ph.D., University of British Columbia

This professor is accepting doctoral students

Publication List