Hans Chen

Ph.D. student in atmospheric sciences at Penn State

  • Hans W. Chen
  • Doctoral Graduate Student
  • Department of Meteorology
  • The Pennsylvania State University


I am a Ph.D. student in the Department of Meteorology at Penn State, working with my advisor Fuqing Zhang. My research interests include atmospheric dynamics, climate variability on interannual to decadal time scales, and how the large scale atmospheric circulation interacts with regional climate. At the moment my research focuses on improving our understanding of the climate dynamics over the pan-Arctic region.


2013–present Ph.D. in Atmospheric Sciences and Meteorology, Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania, United States.
2010–2012 M.S. in Atmospheric Sciences, Oceanography and Climate, Department of Meteorology, Stockholm University, Stockholm, Sweden.
2007–2010 B.S. in Meteorology, Department of Meteorology, Stockholm University, Stockholm, Sweden.

More information can be found in my CV.

Research interests

The focus of my research is to improve our understanding of how the atmospheric circulation affects the regional weather and climate in the mid-latitudes and polar regions. I approach the problems using a combination of observational data, numerical models, and statistical methods. The research topics I am interested in include:

  • Climate variability on the regional scale
  • General circulation of the atmosphere and teleconnection patterns
  • Interaction between large-scale circulation and regional climate
  • Data assimilation as a tool for understanding climate variability

Recent research projects

A robust mode of climate variability in the Arctic: The Barents Oscillation

Worldmap of Köppen types

This project is based on my Master's thesis and examines the robustness of an atmospheric mode known as the Barents Oscillation (BO). The BO was originally identified as the second Empirical Orthogonal Function (EOF) of monthly wintertime sea level pressure anomalies north of 30°N. Contrary to the dominant Arctic Oscillation/North Atlantic Oscillation (AO/NAO) mode, the BO has mainly a meridional structure and was speculated to be important for the heat transport into the Arctic. A subsequent study, however, showed that an artificial BO-like mode could arise purely due to non-stationary in the spatial pattern of the AO/NAO. Thus, it became unclear whether the BO could be considered independently from the AO/NAO. The objective of this study was to investigate if the BO is a real physical mode of atmospheric variability or an artifact of EOF analysis. On the project page you can find more information about the BO and obtain the BO index.

Go to project page

Using the Köppen classification to quantify climate variation and change

Worldmap of Köppen types

When trying to quantify the impact of climate variation and climate change, it is common to use a single scalar variable such as surface temperature. However, it is not given that a change in e.g. surface temperature will have the same impact everywhere; some ecosystems are relatively stable, while others are more sensitive to changes in the regional climate. This project explores a different approach, using the Köppen climate classification to identify the climatic condition in different regions over various time scales. The Köppen classification system was developed empirically based on the vegetation distribution on Earth and combines surface temperature and precipitation into one single metric. The results of this project suggest that the Köppen classification can be used as a diagnostic tool to examine climate variation and climate change.

Go to project page


  • Chen, H. W., Q. Zhang, H. Körnich, and D. Chen, 2013: A robust mode of climate variability in the Arctic: The Barents Oscillation. Geophysical Research Letters, 40, 2856-2861, 10.1002/grl.50551.
  • Chen, D. and H. W. Chen, 2013: Using the Köppen classification to quantify climate variation and change: An example for 1901–2010. Environmental Development, 6, 69-79, 10.1016/j.envdev.2013.03.007.



Slides from my presentations will be available here.


Various free tools I use in my research.

Atmospheric science


  • Git - Powerful version control system. I keep most of my work in Git repositories.
  • Zotero - Reference management software for collecting and organizing bibliographic data.