Here are some proposed research topics to work with graduate and undergraduate students. Based upon these proposed works, students are encouraged to propose their own research plans. Feel free to contact me if you like to know more (yl4728@columbia.edu).
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Project 1: Arctic amplification in observations and global climate model simulations
​Arctic amplification (AA, Figure 1) is the most prominent signature of global climate change. AA has not only exerted profound impacts within the Arctic Circle, but also been claimed to produce more extreme events in mid-latitudes. Therefore, understanding its cause is a great scientific endeavor. In this project, we plan to look into observation records and large-ensemble global climate model simulations to examine the signature of AA.
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This project will be initiated as part of the summer program for undergraduate research at the Department of Atmospheric Sciences, National Taiwan University
Figure 1. Trends in mean surface air temperature over the period 1960 to 2019. The fact that Arctic warms more than the rest of the globe in the past decades signatures the Arctic amplification. Credit: NASA GISS.
Project 2: Sudden stratospheric warming events in high-top and low-top global climate models
Sudden stratospheric warming (SSW) is one of the most prominent stratospheric extreme events, which is accompanied with reversal of stratospheric prevailing westerly winds. However, gap exists between SSWs simulated in state-of-the-art global climate models and observed ones. In this project, we plan to examine SSWs in high-top and low-top global climate models.
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This project will be initiated as part of the summer program for undergraduate research at the Department of Atmospheric Sciences, National Taiwan University.
Cooperative Project: Global land-use change contribution to Arctic climate change
​IPCC AR5 report presented that global land-use change in the past century gave rise to a negative radiative forcing (-0.25 to -0.05 W/m2), which could compensate part of the warming effects from greenhouse gases (see Figure 2). While most of studies focused on the greenhouse gases warming effect on recent Arctic climate change, less attention has been paid to the role of global land-use change. In this project, we aim to quantify the contribution of global land-use change to recent Arctic climate variability using observations and ensemble of global climate model integrations.
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We are looking for students who have interests in understanding the impact of global land-use change (including deforestation and irrigation) on Arctic climate.
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This project will be cooperated with Dr Min-Hui Lo at National Taiwan University and Drs Lorenzo M. Polvani and Michael Previdi at Columbia University.
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We plan to first focus on the land-use impact on Arctic amplification (see Figure 1) and compare it to those from greenhouse gases and other drivers (e.g., carbon dioxide, ozone-depleting substances, and stratospheric ozone).
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Students are encouraged to propose their own research plans to look into, for example, relevant Arctic or global hydrological and energy budget variations.
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Figure 2. Radiative forcings by emissions and climatic drivers from IPCC AR5 report. The story of evolution of radiative forcing bar charts can be seen here!