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The structure of thunderstorm in the atmospheric boundary layer in Beijing area is analysed by using three-year data of tower. It is indicated that the outflow current of the thunderstorm in the lower layer is a sort of density current. An area of evident wind direction shear is found at about half an hour to one hour before the arrival of the gust front.The maximum intensity of the shear can reach 0.35sec-1.The inner structure within the density current is also very complicated. At the nocturnal stable boundary layer in summertime, the development of the convective motions is often triggered due to the instability of the Kelvin-Helmholtz wave. 相似文献
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From July to September of 1990,CH_4 flux measurements were made in Lin'an rice paddies using gradient profiletechniques.Some characteristics of the turbulence structure under the stable conditions have been verified in the surfacelayer according to the in situ measurements.The semi-empirical turbulent parameters β_m,β_h and β_c and their changeswith the stability parameter Ri are given.Observed results indicate that CH_4 flux in the rice-paddy is mainly decided bythe methnogenesis and the process of CH4 transport from internal soils to the atmosphere,and that the CH_4 verticaltransfer is depressed in the stable surface layer.The CH_4 flux shows that its obvious diurnal changes,and the meanCH_4 flux are higher in nighttime and lower in daytime,and the peaks appear at about 2000 BST at night and 0300 BSTin the early morning,respectively.The mean value of CH_4 flux is about 4.18±2.3 mg/m~2 h. 相似文献
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文章讨论了秋季(1994年10月)和冬季(1995年1月)在中国西部青海省共和县瓦里关山(36°17′N,100°54′E,海拔3816 m)基准站和中国东北黑龙江省五常县的龙凤山(44°44′N,127°36′E,海拔331 m)及中国东南沿海的浙江省临安县的横畈乡(30°18′N,119°44′E,海拔131 m)两个区域本底站(上述3站均属WMO)所采集的气溶胶样品的质量浓度、可溶性离子浓度的时空分布特征和变化规律。初步得出:气溶胶质量浓度和可溶性离子浓度以临安为最高。其次是龙凤山,而瓦里关山为最低 相似文献
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一个高精度的测温方法 总被引:1,自引:0,他引:1
本文介绍一种经补偿的不平衡电桥测温方法,电桥输出和测量温度成直线性关系,温度测量范围为-20℃—十45℃,测量精度好于0.l℃。 相似文献
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The characteristics of surface O_3 on clear days at Waliguan Observatory,Lin'an regionalstation and Longfengshan regional station in China were analyzed in this paper.The three stationsbelong to Global Atmospheric Watch(GAW)of WMO.There was obvious daily variation on cleardays at Lin'an.with maximum(42.9 ppb)and minimum(20.3 ppb)of daily range appearing inspring and summer.respectively.The daily variation was more regular at Lonfengshan than atLin'an.The maximum(about 27 ppb)appeared in autumn at Longfengshan.There was noobvious daily variation and also daily range was smaller in other seasons except weaker dailyvariation in summer at Waliguan.But the surface O_3 concentration(SOC)in summer was higherthan that in winter at Waliguan.The SOC on clear days of summer at Waliguan was over 20 ppbhigher than at Longfengshan and Lin'an.The global radiation and NO_x concentration were themain factors which control the SOC on clear days at Longfengshan and Lin'an.and playedimportant role in different seasons and areas.The transportation of air flow around the area ofQinghai-Xizang(Tibet)Plateau was the main cause for high SOC and weak daily variation insummer at Waliguan.The similar effect of transportation was obtained at the Mauna LoaObservatory.The distribution characteristics of SOC increasing with height in the tropospheredetermined the difference of SOC between East China and West China. 相似文献