This seminar will witness three academic reports.
Report 1: Simulated impacts of land cover change on summer climate in the Tibetan Plateau
Presenter: Dr. LI Qian, Institute of Atmospheric Physics, CAS
Abstract:
The Tibetan Plateau (TP) is a key region of land–atmosphere interactions with severe eco-environment degradation. This study uses an atmospheric general circulation model, NCEP GCM/SSiB, to present the major TP summer climate features for six selected ENSO years and preliminarily assess the possible impact of land cover change on the summer circulation over the TP. Compared to Reanalysis II data, the GCM using satellite derived vegetation properties generally reproduces the main 6-year-mean TP summer circulation features despite some discrepancies in intensity and geographic locations of some climate features. Two existing vegetation maps with very different land cover conditions over the TP, one with bare ground and one with vegetation cover, derived from satellite derived data, are tested and produce clearer climate signals due to land cover change. It shows that land cover change from vegetated land to bare ground decreases the radiation absorbed by the surface and results in weaker surface thermal effects, which lead to lower atmospheric temperature, as well as weaker vertical ascending motion, low-layer cyclonic, upper level anticyclonic, and summer monsoon circulation. These changes in circulation cause a decrease in the precipitation in the southeastern TP.
Report 2: Application of the Configurational entropy theory in monthly stream flow forecasting
Presenter: Huijuan Cui, Texas A&M University
Abstract:
Streamflow forecasting is needed for river training and management, river restoration, reservoir operation, power generation, irrigation, and navigation. Configurational entropy theory (CET) is developed for monthly streamflow forecasting. The theory is comprised of three main parts: (1) determination of spectral density (2) determination of parameters by cepstrum analysis, and (3) extension of autocorrelation function. Comparison with the Burg entropy theory (BET) shows that CET yields higher resolution spectral density with more accurate location of spectral peaks. Cepstrum analysis yields more accurate parameters than the Levinson-Burg algorithm in BET. CET is tested using monthly streamflow data from 19 river basins covering a broad range of physiographic characteristics. Testing shows that CET captures streamflow seasonality and satisfactorily forecasts. High flows are satisfactorily forecasted with r2 higher than 0.92 for one year ahead of time, with r2 higher than 0.85 for two years ahead of time, and up to 60 month with r2 higher than 0.80. It is found that upstream streamflow is forecasted more accurately (r2=0.84) than downstream streamflow(r2=0.75).
Report 3: Tracing groundwater recharge sources in a mountain-plain transitional area using stable isotopes and numerical simulation
Presenter: Dr. Yaping Liu, Department of Hydraulic Engineering, Tsinghua University
Venue: No. 915 meeting room, ITP, Beijing
Time: 2.00-5.30 pm, Friday, June 20, 2014
Moderator: Prof. WANG Lei
Welcome to the seminar.