Trends in temperature and precipitation extremes from 1961 to 2008 have been investigated over Circum-Bohai-Sea region, China using daily temperature and precipitation data of 63 meteorological stations. The re- suits...Trends in temperature and precipitation extremes from 1961 to 2008 have been investigated over Circum-Bohai-Sea region, China using daily temperature and precipitation data of 63 meteorological stations. The re- suits show that at most stations, there is a significant increase in the annual frequency of warm days and warm nights, as well as a significant decrease in the annual frequency of cold days, cold nights, frost days, and annual diurnal tem- perature range （DTR）. Their regional averaged changes are 2.06 d/1 0yr, 3.95 d/10yr, -1.88 d/10yr, -4.27 d/10yr, -4.21 d/10yr and -0.20℃/10yr, respectively. Seasonal changes display similar patterns to the annual results, but there is a large seasonal difference. A significant warming trend is detected at both annual and seasonal scales, which is more contributed by changes of indices defined by daily minimum temperature than those defined by daily maximum tem- perature. For precipitation indices, the regional annual extreme precipitation displays a weak decrease in terms of magnitude and frequency, i.e. extreme precipitation days （RD95p）, intensity （RINTEN）, proportion （RPROP） and maximum consecutive wet days （CWD）, but a slight increase in the maximum consecutive dry days （CDD）, which are consistent with changes of annual total precipitation （PRCPTOT）. Seasonally, PRCPTOT and RD95p both exhibit an increase in spring and a decrease in other seasons with the largest decrease in summer, but generally not significant. In summary, this study shows a pronounced warming tendency at the less rainy period over Circum-Bohai-Sea region, which may affect regional economic development and ecological protection to some extent.展开更多
Surface OH radical concentration in Beijing City was measured by impregnated filter trapping technique-high performance liquid chromatography (IFT-HPLC). The observed concentration of OH radical showed obvious diurnal...Surface OH radical concentration in Beijing City was measured by impregnated filter trapping technique-high performance liquid chromatography (IFT-HPLC). The observed concentration of OH radical showed obvious diurnal and seasonal variations, with maximum readings at noon or afternoon, similar to 80x10(6)OH/cm(3) in summer and similar to 20x10(6)-40x10(6)OH/cm(3) in fall. On the basis of measured data, the reaction rates related to the photochemical process of HO(x) (OH+HO(2)) were derived and characteristics of atmospheric chemical processes in the city were analyzed. The results showed that conversion rates of atmospheric OH and HO(2) in the summer of Beijing City were about 700x10(6) molecule/(cm(3) . s) and 600x10(6)molecule/(cm(3) . s), respectively. And the net production of OH in the air of the city mainly originated from the photolysis of the gaseous HNO(2), and the main sink of OH were the photochemical reactions with VOCs, NO(2), HCHO and CO. It was different from the clean area.展开更多
Energy-saving solar greenhouse vegetables cultivating is to create and improve microclimate environment with greenhouse in those seasons impossible for open cultivation production and in order to achieve the purpose o...Energy-saving solar greenhouse vegetables cultivating is to create and improve microclimate environment with greenhouse in those seasons impossible for open cultivation production and in order to achieve the purpose of harvest in advance or in delay. Since a greenhouse needs huge construction expenses and high production costs, only though the improvement of facility utilization can we obtain better economic benefits. Vegetable germination and seedling stage need a long time for ground, so they need smaller standing area. So we concentrated in a small area of cultivation can not only create a suitable environment easily, nurture strong age seedling, but also can avoid greenhouse waste. Make transplanting to greenhouse after Seedlings breeding can effectively reduce the fertility cycle and substantially increase greenhouse utilization.展开更多
基金Under the auspices of National Natural Science Foundation of China (No.40901028)
文摘Trends in temperature and precipitation extremes from 1961 to 2008 have been investigated over Circum-Bohai-Sea region, China using daily temperature and precipitation data of 63 meteorological stations. The re- suits show that at most stations, there is a significant increase in the annual frequency of warm days and warm nights, as well as a significant decrease in the annual frequency of cold days, cold nights, frost days, and annual diurnal tem- perature range （DTR）. Their regional averaged changes are 2.06 d/1 0yr, 3.95 d/10yr, -1.88 d/10yr, -4.27 d/10yr, -4.21 d/10yr and -0.20℃/10yr, respectively. Seasonal changes display similar patterns to the annual results, but there is a large seasonal difference. A significant warming trend is detected at both annual and seasonal scales, which is more contributed by changes of indices defined by daily minimum temperature than those defined by daily maximum tem- perature. For precipitation indices, the regional annual extreme precipitation displays a weak decrease in terms of magnitude and frequency, i.e. extreme precipitation days （RD95p）, intensity （RINTEN）, proportion （RPROP） and maximum consecutive wet days （CWD）, but a slight increase in the maximum consecutive dry days （CDD）, which are consistent with changes of annual total precipitation （PRCPTOT）. Seasonally, PRCPTOT and RD95p both exhibit an increase in spring and a decrease in other seasons with the largest decrease in summer, but generally not significant. In summary, this study shows a pronounced warming tendency at the less rainy period over Circum-Bohai-Sea region, which may affect regional economic development and ecological protection to some extent.
基金Under the auspices of the National Natural Science Foundation of China(No.40075026)
文摘Surface OH radical concentration in Beijing City was measured by impregnated filter trapping technique-high performance liquid chromatography (IFT-HPLC). The observed concentration of OH radical showed obvious diurnal and seasonal variations, with maximum readings at noon or afternoon, similar to 80x10(6)OH/cm(3) in summer and similar to 20x10(6)-40x10(6)OH/cm(3) in fall. On the basis of measured data, the reaction rates related to the photochemical process of HO(x) (OH+HO(2)) were derived and characteristics of atmospheric chemical processes in the city were analyzed. The results showed that conversion rates of atmospheric OH and HO(2) in the summer of Beijing City were about 700x10(6) molecule/(cm(3) . s) and 600x10(6)molecule/(cm(3) . s), respectively. And the net production of OH in the air of the city mainly originated from the photolysis of the gaseous HNO(2), and the main sink of OH were the photochemical reactions with VOCs, NO(2), HCHO and CO. It was different from the clean area.
文摘Energy-saving solar greenhouse vegetables cultivating is to create and improve microclimate environment with greenhouse in those seasons impossible for open cultivation production and in order to achieve the purpose of harvest in advance or in delay. Since a greenhouse needs huge construction expenses and high production costs, only though the improvement of facility utilization can we obtain better economic benefits. Vegetable germination and seedling stage need a long time for ground, so they need smaller standing area. So we concentrated in a small area of cultivation can not only create a suitable environment easily, nurture strong age seedling, but also can avoid greenhouse waste. Make transplanting to greenhouse after Seedlings breeding can effectively reduce the fertility cycle and substantially increase greenhouse utilization.
