Title：Assessing Atmosphere and Land Coupling Stress and Direct/Indirect Effect

Presenter：Prof. Yongkang Xue (Department of Geography and Department of Atmospheric & Oceanic Sciences, University of California, Los Angeles)

Dr. Yongkang Xue studies land surface modeling, land/atmosphere interactions, climate change, regional climate downscaling, and remote sensing. He has been instrumental in the development of the "SSiB" land surface scheme, which has been coupled with a number of GCMs and regional models. Using coupled land-surface/atmosphere models, he has conducted numerous sensitivity and prediction studies to investigate the impact of land-surface processes, including vegetation biophysical processes, land-cover and land use change, and land-surface parameters and parameterizations, on regional climate and global climate variability and anomalies, with a special emphasis on monsoon systems, and the mechanism involved. He also works on the remote sensing methodology for atmospheric and land surface variables. He has developed a number of undergraduate and graduate courses for land surface modeling, climate and environment change, and remote sensing studies.

Chair：Prof. MA Yaoming

Time：15:30, Friday, September 13, 2013

Venue: Room 915, ITP, Beijing

Abstract:

        Land-atmosphere interaction studies have be evolved from simple examining ‘what if’ scenarios, which focused more on the performance of the land models and improvements might be needed in their parameterizations, to suggest role of land surface processes in the climate system, possible future climates and/or what the impact of human activities might be. This presentation discusses two modeling approaches to identify role of land surface processes in the climate system. One method (Koster et al., 2000, 2004, 2006) develops a coherence index between different precipitation time-series based on soil moisture memory and model-produced atmospheric responding to soil moisture to identify the atmosphere/land coupling strength and mechanisms. Another method (Xue et al., 2004, 2006, 2010; Ma 2013) based on different land models’ principles and their produced-atmospheric responding to vegetation biophysical processes (VBP) to identify the A/L coupling strength and possible mechanisms. Both methods suggest the L/A couplings are only strong over certain regions but with discrepancies in some regions that they identified. The indirect effects, i.e., the land effect on the sea surface temperature and ENSO, with second method are discussed.