Recorded presentationJ5.5
Detection and Analysis of the Climatic Signal of Land Use Change on the Tibetan Plateau
Jiming Jin, Lawrence Berkeley National Laboratory/Univ. of California, Berkeley, CA; and N. L. Miller
In this study, we use high-quality observations and the NCAR Single Column Atmosphere Model version 3.1 coupled with the Community Land Model version 2 (SCAM-CLM) to detect and quantify the climatic response of land use change over the Tibet Plateau (TP). The detailed oneyear hourly observations from a station near Mount Everest (coordinate: 28.365șN, 86.948ș E; elevation: 4,300m) and a station near the Namucuo River (coordinate: 30.774șN, 90.989șE; elevation: 4,730m) were used to evaluate SCAM-CLM. These observations from the Chinese Academy of Sciences include the near-surface air temperature, precipitation, radiation, surface heat fluxes, soil temperate, and soil moisture content. The results show that the SCAM-CLM model is able to realistically reproduce the observations over this region. Our analysis of observations further indicates that a warming trend over a time span of 50 years (1951-2000) is seen at the TP Lhasa and Golmud stations, where significant land use change has occurred during last century. To quantify the role of the land use change in the local climate system, two sets of additional simulations were performed at these two stations. The first set of 50-year SCAM-CLM simulations (1951-2000) were forced with cropland and bare soil, where the lateral boundary and initial conditions were provided by the six-hour National Centers for Environmental Prediction Reanalysis data. The second set of 50-year simulations were forced with the natural vegetation cover that was present prior to the land use change. This past land surface type is based on the surface surveys that indicate the natural vegetation cover at or near our selected meteorological stations were mostly grassland and woodland. These two sets of simulations were compared and contrasted as a sensitivity analysis to quantitatively understand the climatic consequences of land use change over the TP. Our results show that agricultural expansion and urbanization have amplified the warming signal as a result of the decreased natural vegetation cover that lowers surface evaporation. Detailed physical processes and mechanisms associated with the climatic response of the TP land use changes are also fully investigated and presented. Recorded presentation
Joint Session 5, Land-Atmosphere Interactions, Part V
Wednesday, 23 January 2008, 10:30 AM-11:45 AM, 224
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