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
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
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
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.
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.
