Welcome to Tianle Yuan's research page!
Clouds are one of the most important and challenging components of our climate system due to their strong influence on the radiative balance and their highly non-linear nature. Aerosols (small airborne particles) due to human activities affect the energetics of Earth's climate both directly and indirectly through interacting with clouds. My research focuses on understanding complex interactions within the aerosol-cloud-chemistry-climate system using satellite observations together with numerical models as well as theory. These interactions are relevant not only for processes that have short temporal and limited spatial scales but also for those that affect long-term, global climate variations. However, there remains a large gap in our understanding of these interactions and their impact on climate and weather.
Image is made using online materials from various sources (mainly NASA). Credit is due to their original composers.
This mosaic image shows an ensemble of clouds of different types. Clockwise from the upper-left corner: part of a stratocumulus deck is breaking up into open cell convections while others remain intact; ships are making so called shiptracks that are much brighter than the background due to both their larger cloud fraction and higher reflectivity; organized deep convective cloud complex; outer convective bands of Hurricane (ultimate organized convection) Ike, 2008. See the following and my research page for more.
Here are a few general subjects I am working on:
(1) Cloud physics and dynamics: Spatial and temporal scales of cloud processes span a large number of decades, from micrometers to thousands of kilometers. This makes studying clouds extremely challenging. Current cloud models typically represent processes within certain scale range and those outside of this range are either ignored or parameterized. Both practices inevitably introduce incomplete description of the system. I am trying new ways to connect cloud processes at different scales with a cloud statistical mechanics approach. (2) Aerosol-cloud-chemistry interactions: At the smallest scale of cloud processes sit aerosol particles. They are the starting point of cloud formation. Therefore, changes in aerosol properties propogate into many different cloud processes and affect cloud micro- and macro- physical properties, which has important concequences for atmospheric chemistry, radiation, dynamics and thus climate. Understanding of these aerosol-cloud-chemistry-climate interactions is still limited, which increases the uncertainty of climate projection. (3) Satellite meteorology and remote sensing : Satellites are the ultimate observational tools for large-scale phenomena in meteorology and climate sciences such as clouds, aerosol transport, and radiative energy balance of the Earth. Recent advances in sensor capabilities have made it possible to study these phenomena at incredible details. Information burried in these multiplatform, multi-spectral and multi-angle satellite sensors provides unprecedent opportunity for remote sensing technique development and to advance our understanding of the cliamte system. (4) Radiative effects of aerosols and clouds : Both aerosols and clouds exert strong influence on the radiative balance of the Earth by reflecting and absorbing radiation. The radiative effect depends critically not only on their physical nature, but also their placement and environment. Furthermore, it is the human-induced change in their radiative effect that is most relevant for climate studies. These aspects of radiative effects of aerosols and clouds require extensive research.
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