Soil moisture plays an important role in land-atmosphere interactions. It is an important geophysical parameter in research on climate, hydrology, agriculture, and forestry. Soil moisture has important climatic effect...Soil moisture plays an important role in land-atmosphere interactions. It is an important geophysical parameter in research on climate, hydrology, agriculture, and forestry. Soil moisture has important climatic effects by influencing ground evapotranspi ration, runoff, surface reflectivity, surface emissivity, surface sensible heat and latent heat flux. At the global scale, the extent of its influence on the atmosphere is second only to that of sea surface temperature. At the terrestrial scale, its influence is even greater than that of sea surface temperatures. This paper presents a China Land Soil Moisture Data Assimilation System (CLSMDAS) based on EnKF and land process models, and results of the application of this system in the China Land Soil Moisture Data Assimilation tests. CLSMDAS is comprised of the following components: 1) A land process mo del—Community Land Model Version 3.0 (CLM3.0)—developed by the US National Center for Atmospheric Research (NCAR); 2) Precipitation of atmospheric forcing data and surface-incident solar radiation data come from hourly outputs of the FY2 geostationary meteorological satellite; 3) EnKF (Ensemble Kalman Filter) land data assimilation method; and 4) Observa tion data including satellite-inverted soil moisture outputs of the AMSR-E satellite and soil moisture observation data. Results of soil moisture assimilation tests from June to September 2006 were analyzed with CLSMDAS. Both simulation and assimila tion results of the land model reflected reasonably the temporal-spatial distribution of soil moisture. The assimilated soil mois ture distribution matches very well with severe summer droughts in Chongqing and Sichuan Province in August 2006, the worst since the foundation of the People’s Republic of China in 1949. It also matches drought regions that occurred in eastern Hubei and southern Guangxi in September.展开更多
In this paper,the following assumptions are made:1) seismic source is a point one;2) the near-fieid.seismic waves are body ones:3) the medium of the earth is a half-space which is homogeneous and elastic.Yccording to ...In this paper,the following assumptions are made:1) seismic source is a point one;2) the near-fieid.seismic waves are body ones:3) the medium of the earth is a half-space which is homogeneous and elastic.Yccording to the above-mentioned assumptions,this paper obtains a theoretical formula to estimate S-wave incident angle by using the record of strong ground motion.During the process of calculations,the paper also presents a method of getting in-plane and inti-plane motions from the record of strong ground motion.By making use of 214 records of strong ground motion in the western America,this paper gives a statistical relation among S-wave incident angle,epicentral distance and frequency.The results show that the average value of S-wave incident angle is about 57,and has little to do with the epicentral distance.展开更多
The reflection of oblique incident waves from breakwaters with a partially-perforated front wall is investigated. The fluid domain is divided into two sub-domains and the eigenfunction expansion method is applied to e...The reflection of oblique incident waves from breakwaters with a partially-perforated front wall is investigated. The fluid domain is divided into two sub-domains and the eigenfunction expansion method is applied to expand velocity potentials in each domain. In the eigen-expansion of the velocity potential, evanescent waves are included. Numerical results of the present model are compared with experimental data. The effect of porosity, the relative chamber width, the relative water depth in the wave absorbing chamber and the water depth in front of the structure are discussed.展开更多
基金supported by National High Technology Research and Development Program of China (Grant Nos. 2007AA12Z144, 2009AA12Z129)Chinese COPES Project (Grant Nos. GYHY200706005, GYHY200806014)China Meteorological Administration New Technology Promotion Project (Grant No. CMATG2008Z04)
文摘Soil moisture plays an important role in land-atmosphere interactions. It is an important geophysical parameter in research on climate, hydrology, agriculture, and forestry. Soil moisture has important climatic effects by influencing ground evapotranspi ration, runoff, surface reflectivity, surface emissivity, surface sensible heat and latent heat flux. At the global scale, the extent of its influence on the atmosphere is second only to that of sea surface temperature. At the terrestrial scale, its influence is even greater than that of sea surface temperatures. This paper presents a China Land Soil Moisture Data Assimilation System (CLSMDAS) based on EnKF and land process models, and results of the application of this system in the China Land Soil Moisture Data Assimilation tests. CLSMDAS is comprised of the following components: 1) A land process mo del—Community Land Model Version 3.0 (CLM3.0)—developed by the US National Center for Atmospheric Research (NCAR); 2) Precipitation of atmospheric forcing data and surface-incident solar radiation data come from hourly outputs of the FY2 geostationary meteorological satellite; 3) EnKF (Ensemble Kalman Filter) land data assimilation method; and 4) Observa tion data including satellite-inverted soil moisture outputs of the AMSR-E satellite and soil moisture observation data. Results of soil moisture assimilation tests from June to September 2006 were analyzed with CLSMDAS. Both simulation and assimila tion results of the land model reflected reasonably the temporal-spatial distribution of soil moisture. The assimilated soil mois ture distribution matches very well with severe summer droughts in Chongqing and Sichuan Province in August 2006, the worst since the foundation of the People’s Republic of China in 1949. It also matches drought regions that occurred in eastern Hubei and southern Guangxi in September.
基金the Joint Earthquake Science Foundation of China
文摘In this paper,the following assumptions are made:1) seismic source is a point one;2) the near-fieid.seismic waves are body ones:3) the medium of the earth is a half-space which is homogeneous and elastic.Yccording to the above-mentioned assumptions,this paper obtains a theoretical formula to estimate S-wave incident angle by using the record of strong ground motion.During the process of calculations,the paper also presents a method of getting in-plane and inti-plane motions from the record of strong ground motion.By making use of 214 records of strong ground motion in the western America,this paper gives a statistical relation among S-wave incident angle,epicentral distance and frequency.The results show that the average value of S-wave incident angle is about 57,and has little to do with the epicentral distance.
基金by Joint Fund of the National Natural Science Foundation of China the Hong Kong Science Research Bureau (49910161985)+1 种基金the National Natural Science Foundation of China (50025924,50179004)the Research Fund for the Development of harbor engineeri
文摘The reflection of oblique incident waves from breakwaters with a partially-perforated front wall is investigated. The fluid domain is divided into two sub-domains and the eigenfunction expansion method is applied to expand velocity potentials in each domain. In the eigen-expansion of the velocity potential, evanescent waves are included. Numerical results of the present model are compared with experimental data. The effect of porosity, the relative chamber width, the relative water depth in the wave absorbing chamber and the water depth in front of the structure are discussed.
