Dr. Yu is an expert in climate modeling, dynamics, and diagnosis, and his research covers global-scale climate changes to regional-scale variations in monsoons. He is renowned for his contributions to our understanding of El Nino diversity and complexity, and inter-basin interactions among the Pacific, Atlantic, and Indian Oceans. He discovered a new breed of El Nino and termed it "Central Pacific El Nino", which has since been widely accepted in the scientific community. His contributions also include proposing a wave-mean flow interaction theory to explain the north-south oscillation of the jet stream in the atmosphere, which is now known as the Arctic Oscillation or the Annular Mode.

Dr. Yu has received several awards and honors, including the Advances in Atmospheric Sciences Outstanding Editor Award, the American Geophysical Union Editors' Citation for Excellence, and being listed in the Thomson Reuters list of the world's top 1000 climate scientists. He is a Fellow of the Meteorology Society of Taiwan. In addition to his research, Dr. Yu is dedicated to teaching and was awarded the Teaching Contribution Award by the School of Physical Sciences at the University of California, Irvine. He has also served as the Vice Chair of the Department of Earth System Science.