Speaker: Dr. Songjun Han, China Institute of Water Resources and Hydropower Research

　　Topics:Derivation of a sigmoid generalized complementary function for evaporation with physical constraints

　　Time: 3:30 pm, April 11, 2019 

　　Location: Meeting room 203, State Key Lab.of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation

　　A Brief Introduction to the Speaker:

　　Dr. Songjun Han received his Ph.D. degree in Tsinghua University in 2008. After graduation, Dr. Han has started his career at the department of irrigation and drainage, China Institute of Water Resources and Hydropower Research, and is a professor now. Dr. Han’s research focuses on the evapotranspiration process. He serves as an Associate Editor of the international journal, Hydrological Processes. Dr. Han has authored 22 peer-reviewed international journal papers, including Water Resources Research, and Invited Commentaries in Hydrological Processes, one of which won the 2015 Wiley Award for Top Cited Invited Commentary. Dr. Han won the first prize for Science & technology Development/Achievement of the Ministry of Education, and the second prize for Agricultural Eater Saving Technology. 

　　Complementary principle is one of the main methodologies on evapotranspiration research. The traditional complementary principle relies on the linear complementary relationship, which has a disadvantage. Different from the traditional methodology, Dr. Han proposed a nonlinear function approach, and derived and verified a sigmoid function by invoking boundary conditions. The nonlinear function approach supplies a new framework for the research of complementary principle, and is named as "generalized complementary principle". The work has inspired Professor Wilfried Brutsaert to adopt a similar method, and has been widely accepted by the research community.