Influence Of Land Surface Boundary Condions (Such As LAI) On The Regional Climate Simulation And Preparation Of Land Surface Remotely-sensed Parameters For Regional Climate Model (CWRF+CLM)

IPCC reports in Shanghai in January 2001 point out that: the global average surface temperature has increased over over ther the last 50 years and there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.Land use/land cover change due to the anthropic activities is one way affecting climatic change. Numerical prediction model is one efficient research method in understanding weather as well as the climatic change. The land surface sub-module in the climate model is the parameterization scheme, delineating the earth's surface physics and the biochemistry process, formulating matter and energy exchange in the interface of surface and atmosphere. The limitation of surface observation and the large spatial-temporal variability of land surface parameters restricted accuracy qualification of the land surface physical process, the remote sensing database provides an opportunity for more accurate description of the flux exchange between the interface of land and atmosphere without doubt, and further to improve the region climate model simulation performance. The data assimilation has provided a bridge for the remote sensing data fusing into the region climate and the land surface model, and thus the first problem to solve is preparing the numerical prediction model with perfect simulation performance as well as preparing the remote sensing datasets matched with the numerical prediction model in spatial-temporal resolution and reasonable in physics. Based on the above facts and problems, this thesis focuses the following works: studying the climate response resulted from the leaf area index (LAI) during 1982-1999;evaluating propagated error caused from inter-annual variability of LAI;developing the surface parameters preprocessing system from the real-time satellite remotely-sensed datasets to regional climate model;and introducing inter-annual variability of land surface parameters into land surface model. The main research conclusions and achievements can be summeried as follows:1) The Chinese precipitation, temperature, sunshine hour, relative humidity and 500hPa wind field from 1961-2000 are analyzed, indicating there exist climatic jump, easily appearing at ecologically frail area and the climate sensitive area, obvious about 1984 and about 1993.2) The inter-monthly and inter-annual variability of leaf area index, as an important parameter in water-heat calculation of land surface process, directly or indirectly affect the water-heat calculation related to land surface process. The propagated error from the inter-annual variability of leaf area index is larger than 15% in some place of China, which will be further propagated into boundary layer. The inter-annual variability of LAI has been introduced into CLM3.3) In a certain degree the numerical simulation through static and dynamic leaf area index with different land surface characteristics indicate the effect of LAI on the simulation from 1982 to 1999. No obvious difference occurs for the first REOF load vector under these two different conditions, only for the second and third with larger difference, which prove that the LAI contributes to the high-frequency section of climatic change.4) Separately using the LAI from MODIS and from CLM multi-year monthly average, the simulations have been done in January 2003 and July 2003, and difference chart of monthly-mean divergence and the temperature field from these two different simulations are analyzed. The results indicated that: the LAI change inspires relatively smaller response in January, without surpassing 700hPa, but in July, the influence of LAI difference is not negligible, and in 300hPa the difference of the temperature field and the divergence field is still larger, which is related possibly to the plateau terrain non-linearity strengthens.5) Based on AVHRR and MODIS products, we developed the surface parameters preprocessing system from the real-time MODIS Level two land surface products to regional climate model resolutions. Has produced the land surface parameter database needed by the region climate model and the land surface model, including: LAI database;Surface temperature;Surface emissivity;Surface land cover change;Vegetation index;Bidirectional albedo;Snow deep database, land surface river system characteristic database and so on.In brief, this thesis examined the sensitive influence due to the leaf area index uncertainty in three different perspectives, i.e. in the variables related to LAI in the water-heat calculation, land surface model CLM and regional climate model CWRF. The roles of LAI in the land surface model and regional climate model are analyzed. Based on the above facts and needs, we developed the surface parameters preprocessing system from the real-time MODIS Level two land surface products to regional climate model resolution, and the land surface parameter datasets from which provide the data foundation for the further data assimilation and the accurate simulation of region climate.