Total Cloud Cover （TCC） over China deter- mined from four climate datasets including the Interna- tional Satellite Cloud Climatology Project （ISCCP）, the 40-year Re-Analysis Project of the European Centre for Medi...Total Cloud Cover （TCC） over China deter- mined from four climate datasets including the Interna- tional Satellite Cloud Climatology Project （ISCCP）, the 40-year Re-Analysis Project of the European Centre for Medium-Range Weather Forecasts （ERA-40）, Climate Research Unit Time Series 3.0 （CRU3）, and ground sta- tion datasets are used to show spatial and temporal varia- tion of TCC and their differences. It is demonstrated that the four datasets show similar spatial pattern and seasonal variation. The maximum value is derived from ISCCE TCC value in North China derived from ERA-40 is 50% larger than that from the station dataset; however, the value is 50% less than that in South China. The annual TCC of ISCCP, ERA-40, and ground station datasets shows a decreasing trend during 1984-2002; however, an increasing trend is derived from CRU3. The results of this study imply remarkable differences of TCC derived from surface and satellite observations as well as model simu- lations. The potential effects of these differences on cloud climatology and associated climatic issues should be carefully considered.展开更多
The data series of monthly clouldiness over global ocean from COADS was compared with that of from satellite Nimbus-7 during April 1979 to March 1985. The correspondence between them is good. Both the two methods of o...The data series of monthly clouldiness over global ocean from COADS was compared with that of from satellite Nimbus-7 during April 1979 to March 1985. The correspondence between them is good. Both the two methods of observation can provide useful information of the distribution of cloudiness and the two data sets can be mutually complementary.展开更多
With Empirical Orthogonal Function （EOF） and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai-Tibet Plateau during the period 1971-2004. A...With Empirical Orthogonal Function （EOF） and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai-Tibet Plateau during the period 1971-2004. Analysis indicates that the total cloud amount decreases from the southeast to the northwest of the plateau, and that the annual and seasonal variations in total cloud amount both show an apparent declining tendency over the past decades. Correlation analysis demonstrates that the total cloud amount is negative with sunshine duration and diurnal temperature range （DTR）, and is positive with precipitation and the relative humidity, respectively. The negative correlation is consistent with the radiative effect of cloud, while the positive correlation between total cloud amount and precipitation is obscured because of the influence of topographic factors. Discussion implies that the decrease of total cloud amount is possibly due to the variation of atmospheric aerosol content and ozone concentration over the plateau, although it is difficult to quantify the driving force mechanism up to now.展开更多
[ Objective] The research aimed to study influences of the climate warming on cloudage and cloud-like structure in southern China. [ Method] Annual average temperature, total cloudage and low cloudage in Gan County, N...[ Objective] The research aimed to study influences of the climate warming on cloudage and cloud-like structure in southern China. [ Method] Annual average temperature, total cloudage and low cloudage in Gan County, Nankang, Shangyou and Xinfeng of southern Jiangxi from 2004 to 2011 were selected. Influences of the annual average temperature change on annual average total cloudage, annual average low cloudage and cloud-like structure in southern Jiangxi were analyzed. [ Result] Climate warming was affecting cloudage and cloud-like structure in southern China. When annual average temperature rose, annual average total cloudage and low cloudage both presented decrease trends. When annual av- erage temperature declined, annual average total cloudage and low cloudage both presented rise trends. When annual average temperature was equal to that in prior year at low point, annual average total cloudage and low cloudage increased. Annual average low cloudage was different in mountain area and basin. Influences of the annual average temperature on annual average total cloudage and low cloudage in basin at the low alti- tude presented slow fluctuation form, and had severe influence on that in mountain area at the high altitude. Rise of the annual average temperature had larger influence on high cloudage, while decline of the annual average temperature had larger influence on annual average low cloudage. Under different weather situations, formation and disappearance change of the low cloud had different manifestation forms. [ Conclusion] The research provided scientific basis for studying changes of the cloudage and cloud-like structure in southern China as climate warming.展开更多
三维点云数据建模是三维重建的核心技术,广泛应用于医学、工业检测及文化遗产保护等领域。文章系统梳理了点云数据的结构与获取方法(如激光扫描、多视图成像),重点分析了基于隐式表示法的表面重建算法。该类算法通过隐式函数描述三维表...三维点云数据建模是三维重建的核心技术,广泛应用于医学、工业检测及文化遗产保护等领域。文章系统梳理了点云数据的结构与获取方法(如激光扫描、多视图成像),重点分析了基于隐式表示法的表面重建算法。该类算法通过隐式函数描述三维表面,擅长处理复杂的拓扑结构,但在面对噪声、稀疏数据及复杂场景时存在局限。为解决这些问题,文章提出了一种基于总变差(Total Variation,TV)正则化的改进算法,利用TV项抑制噪声并保持边界锐利性,结合交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)优化目标函数,显著提升了重建精度与鲁棒性。实验表明,改进算法在噪声环境或数据缺失场景下,能有效消除伪影并保留细节,重建质量优于传统方法。展开更多
This study attempts to investigate the interaction between lower and upper atmosphere, employing daily data of Total Ozone Column (TOC) and atmospheric parameter (cloud cover) over Nigeria from 1998-2012;in order to s...This study attempts to investigate the interaction between lower and upper atmosphere, employing daily data of Total Ozone Column (TOC) and atmospheric parameter (cloud cover) over Nigeria from 1998-2012;in order to study the dynamic effect of ozone on climate and vice versa. This is due to the fact that ozone and climate influence each other and the understanding of the dynamic effect of the interconnectivity is still an open research area. Monthly mean daily TOC and cloud cover data were obtained from the Earth Probe Total Ozone Mass Spectroscopy (EPTOMS) and the International Satellite Cloud Climatology Project (ISCCP)-D2 datasets respectively. Bivariate analysis and Mann Kendall trend tests were used in data analysis. MATLAB and ArcGIS software were employed in analyzing the data. Results reveal that TOC increased spatially from the coastal region to the north eastern region of the country. Seasonally, the highest value of TOC was observed at the peak of rainy season when cloud activity is very high, while the lowest value was recorded in dry season. These variations were attributed to rain producing mechanisms and atmospheric phenomena which influence the transport and distribution of ozone. Furthermore, the statistical analysis reveals significant relationship between TOC and low and middle cloud covers in contrast to high cloud cover. This relationship is consistent with previous studies using other atmospheric variables. This study has given scientific insight which is useful in understanding the coupling of the lower and upper atmosphere.展开更多
基金supported by the "Strategic Priority Research Program" of the Chinese Academy of Sciences(XDA05100300)the National Basic Research Program of China(2013CB955801)the National Natural Science Foundation of China(41175030)
文摘Total Cloud Cover （TCC） over China deter- mined from four climate datasets including the Interna- tional Satellite Cloud Climatology Project （ISCCP）, the 40-year Re-Analysis Project of the European Centre for Medium-Range Weather Forecasts （ERA-40）, Climate Research Unit Time Series 3.0 （CRU3）, and ground sta- tion datasets are used to show spatial and temporal varia- tion of TCC and their differences. It is demonstrated that the four datasets show similar spatial pattern and seasonal variation. The maximum value is derived from ISCCE TCC value in North China derived from ERA-40 is 50% larger than that from the station dataset; however, the value is 50% less than that in South China. The annual TCC of ISCCP, ERA-40, and ground station datasets shows a decreasing trend during 1984-2002; however, an increasing trend is derived from CRU3. The results of this study imply remarkable differences of TCC derived from surface and satellite observations as well as model simu- lations. The potential effects of these differences on cloud climatology and associated climatic issues should be carefully considered.
文摘The data series of monthly clouldiness over global ocean from COADS was compared with that of from satellite Nimbus-7 during April 1979 to March 1985. The correspondence between them is good. Both the two methods of observation can provide useful information of the distribution of cloudiness and the two data sets can be mutually complementary.
基金National Basic Research Program of China, No.2005CB422006 National Natural Science Foundation of China, No.40331006+2 种基金 No.40201005 Knowledge Innovation Project of the CAS, No.KZCX2-YW-310 No.CXI0G-A04-03 The authors would like to thank Climatic Data Center of National Meteorological Information Center Climatic Data Center of National Meteorological Information Center for providing the meteorological data.
文摘With Empirical Orthogonal Function （EOF） and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai-Tibet Plateau during the period 1971-2004. Analysis indicates that the total cloud amount decreases from the southeast to the northwest of the plateau, and that the annual and seasonal variations in total cloud amount both show an apparent declining tendency over the past decades. Correlation analysis demonstrates that the total cloud amount is negative with sunshine duration and diurnal temperature range （DTR）, and is positive with precipitation and the relative humidity, respectively. The negative correlation is consistent with the radiative effect of cloud, while the positive correlation between total cloud amount and precipitation is obscured because of the influence of topographic factors. Discussion implies that the decrease of total cloud amount is possibly due to the variation of atmospheric aerosol content and ozone concentration over the plateau, although it is difficult to quantify the driving force mechanism up to now.
文摘[ Objective] The research aimed to study influences of the climate warming on cloudage and cloud-like structure in southern China. [ Method] Annual average temperature, total cloudage and low cloudage in Gan County, Nankang, Shangyou and Xinfeng of southern Jiangxi from 2004 to 2011 were selected. Influences of the annual average temperature change on annual average total cloudage, annual average low cloudage and cloud-like structure in southern Jiangxi were analyzed. [ Result] Climate warming was affecting cloudage and cloud-like structure in southern China. When annual average temperature rose, annual average total cloudage and low cloudage both presented decrease trends. When annual av- erage temperature declined, annual average total cloudage and low cloudage both presented rise trends. When annual average temperature was equal to that in prior year at low point, annual average total cloudage and low cloudage increased. Annual average low cloudage was different in mountain area and basin. Influences of the annual average temperature on annual average total cloudage and low cloudage in basin at the low alti- tude presented slow fluctuation form, and had severe influence on that in mountain area at the high altitude. Rise of the annual average temperature had larger influence on high cloudage, while decline of the annual average temperature had larger influence on annual average low cloudage. Under different weather situations, formation and disappearance change of the low cloud had different manifestation forms. [ Conclusion] The research provided scientific basis for studying changes of the cloudage and cloud-like structure in southern China as climate warming.
文摘三维点云数据建模是三维重建的核心技术,广泛应用于医学、工业检测及文化遗产保护等领域。文章系统梳理了点云数据的结构与获取方法(如激光扫描、多视图成像),重点分析了基于隐式表示法的表面重建算法。该类算法通过隐式函数描述三维表面,擅长处理复杂的拓扑结构,但在面对噪声、稀疏数据及复杂场景时存在局限。为解决这些问题,文章提出了一种基于总变差(Total Variation,TV)正则化的改进算法,利用TV项抑制噪声并保持边界锐利性,结合交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)优化目标函数,显著提升了重建精度与鲁棒性。实验表明,改进算法在噪声环境或数据缺失场景下,能有效消除伪影并保留细节,重建质量优于传统方法。
文摘This study attempts to investigate the interaction between lower and upper atmosphere, employing daily data of Total Ozone Column (TOC) and atmospheric parameter (cloud cover) over Nigeria from 1998-2012;in order to study the dynamic effect of ozone on climate and vice versa. This is due to the fact that ozone and climate influence each other and the understanding of the dynamic effect of the interconnectivity is still an open research area. Monthly mean daily TOC and cloud cover data were obtained from the Earth Probe Total Ozone Mass Spectroscopy (EPTOMS) and the International Satellite Cloud Climatology Project (ISCCP)-D2 datasets respectively. Bivariate analysis and Mann Kendall trend tests were used in data analysis. MATLAB and ArcGIS software were employed in analyzing the data. Results reveal that TOC increased spatially from the coastal region to the north eastern region of the country. Seasonally, the highest value of TOC was observed at the peak of rainy season when cloud activity is very high, while the lowest value was recorded in dry season. These variations were attributed to rain producing mechanisms and atmospheric phenomena which influence the transport and distribution of ozone. Furthermore, the statistical analysis reveals significant relationship between TOC and low and middle cloud covers in contrast to high cloud cover. This relationship is consistent with previous studies using other atmospheric variables. This study has given scientific insight which is useful in understanding the coupling of the lower and upper atmosphere.
