从理论上分析了起伏飞行测量对GT航空重力测量的影响程度;为了有效地验证起伏飞行的测量效果,开展平坦地形、起伏地形下的一系列缓起伏飞行测试,并分别对GT-2A直升机、固定翼航空重力缓起伏飞行测量结果进行了评价;测试结果表明:采用坡...从理论上分析了起伏飞行测量对GT航空重力测量的影响程度;为了有效地验证起伏飞行的测量效果,开展平坦地形、起伏地形下的一系列缓起伏飞行测试,并分别对GT-2A直升机、固定翼航空重力缓起伏飞行测量结果进行了评价;测试结果表明:采用坡度不超过3.0°(爬升率约1/20)的缓起伏飞行方法是可行的,其重复测量内符合精度均小于0.7 m Gal,满足了高精度测量的要求。展开更多
Following classical theory,a two-layer frontal model is designed.It assumes that frontal surface is the zero-order discontinuity of density.In this paper,the model is used to study orographically distorted and occlude...Following classical theory,a two-layer frontal model is designed.It assumes that frontal surface is the zero-order discontinuity of density.In this paper,the model is used to study orographically distorted and occluded fronts.It is indi- cated that the distortion and occlusion of cold fronts are different under different conditions of orography.Frontal in- tensity also influences the distortion and occlusion.Some rules are revealed and compared with observations.In addition,we have analysed the vertical structure of cold front above mountains and found that frontal surface may be bulged under the influence of orography when it climes the mountain.The bulge of frontal surface is just like the bore as pointed out by Long (1972) when he analysed fluid over obstacles.展开更多
Orographic effects on monthly-and seasonal-scale low frequency oscillation are investiged in terms of a five-level global spectral model with a triangle truncation at wavenumber 10 that contains relatively full physic...Orographic effects on monthly-and seasonal-scale low frequency oscillation are investiged in terms of a five-level global spectral model with a triangle truncation at wavenumber 10 that contains relatively full physical parameterization, followed by analysis and comparison of the lowpass filtered data separately obtained from models with and without orography. Results show that remarkable seasonal characteristics are displayed in the orographic forcing-generated low frequency wavetrain on monthly and seasonal scales. It is found that the Northern Hemisphere summer orography-produced tropical heating acts as source of the low-frequency wavetrain for both hemispheres. Besides, the simulations indicate that the orographic wavetrain perturbation can give rise to the anomaly in the equatorial zonal flow, whose transient forcing will cause a new wavetrain in the Southern Hemisphere, thus completing the cross-equatorial propagation of the northern wave in interhemispheric action.展开更多
利用常规气象观测资料、NCEP/NCAR再分析资料以及雷达、卫星等资料,对2013年6月21日和2014年8月11日遵义市习水河流域两次局地特大暴雨的天气形势场,热力、动力和水汽条件,结合地形特征进行对比分析。结果表明:16.21暴雨大陆高压控制我...利用常规气象观测资料、NCEP/NCAR再分析资料以及雷达、卫星等资料,对2013年6月21日和2014年8月11日遵义市习水河流域两次局地特大暴雨的天气形势场,热力、动力和水汽条件,结合地形特征进行对比分析。结果表明:16.21暴雨大陆高压控制我国中东部地区,受高压阻挡,低层低涡切变主要影响四川中东部,低涡未整体东移,仅850 h Pa冷式切变影响遵义西北部;8.11暴雨降水区中低层处于槽前正涡度区,高层200 h Pa处于南亚高压脊线附近,垂直方向上存在正向环流圈,受副高稳定维持阻挡,中低层低涡切变及地面辐合线东移缓慢,较长时间停留在强降水区域。2两次过程雷达回波反射率因子均呈带状分布,且回波移动方向与带状回波长轴一致,具有典型的"列车效应",剖面显示均为低质心结构,降水效率高。36.21暴雨能量条件比8.11暴雨好,但水汽条件和动力条件不及8.11暴雨。4受习水河谷地形影响,6.21暴雨和8.11暴雨强降雨落区分别与习水河谷赤水段和习水段走向一致。展开更多
文摘从理论上分析了起伏飞行测量对GT航空重力测量的影响程度;为了有效地验证起伏飞行的测量效果,开展平坦地形、起伏地形下的一系列缓起伏飞行测试,并分别对GT-2A直升机、固定翼航空重力缓起伏飞行测量结果进行了评价;测试结果表明:采用坡度不超过3.0°(爬升率约1/20)的缓起伏飞行方法是可行的,其重复测量内符合精度均小于0.7 m Gal,满足了高精度测量的要求。
文摘Following classical theory,a two-layer frontal model is designed.It assumes that frontal surface is the zero-order discontinuity of density.In this paper,the model is used to study orographically distorted and occluded fronts.It is indi- cated that the distortion and occlusion of cold fronts are different under different conditions of orography.Frontal in- tensity also influences the distortion and occlusion.Some rules are revealed and compared with observations.In addition,we have analysed the vertical structure of cold front above mountains and found that frontal surface may be bulged under the influence of orography when it climes the mountain.The bulge of frontal surface is just like the bore as pointed out by Long (1972) when he analysed fluid over obstacles.
文摘Orographic effects on monthly-and seasonal-scale low frequency oscillation are investiged in terms of a five-level global spectral model with a triangle truncation at wavenumber 10 that contains relatively full physical parameterization, followed by analysis and comparison of the lowpass filtered data separately obtained from models with and without orography. Results show that remarkable seasonal characteristics are displayed in the orographic forcing-generated low frequency wavetrain on monthly and seasonal scales. It is found that the Northern Hemisphere summer orography-produced tropical heating acts as source of the low-frequency wavetrain for both hemispheres. Besides, the simulations indicate that the orographic wavetrain perturbation can give rise to the anomaly in the equatorial zonal flow, whose transient forcing will cause a new wavetrain in the Southern Hemisphere, thus completing the cross-equatorial propagation of the northern wave in interhemispheric action.
文摘利用常规气象观测资料、NCEP/NCAR再分析资料以及雷达、卫星等资料,对2013年6月21日和2014年8月11日遵义市习水河流域两次局地特大暴雨的天气形势场,热力、动力和水汽条件,结合地形特征进行对比分析。结果表明:16.21暴雨大陆高压控制我国中东部地区,受高压阻挡,低层低涡切变主要影响四川中东部,低涡未整体东移,仅850 h Pa冷式切变影响遵义西北部;8.11暴雨降水区中低层处于槽前正涡度区,高层200 h Pa处于南亚高压脊线附近,垂直方向上存在正向环流圈,受副高稳定维持阻挡,中低层低涡切变及地面辐合线东移缓慢,较长时间停留在强降水区域。2两次过程雷达回波反射率因子均呈带状分布,且回波移动方向与带状回波长轴一致,具有典型的"列车效应",剖面显示均为低质心结构,降水效率高。36.21暴雨能量条件比8.11暴雨好,但水汽条件和动力条件不及8.11暴雨。4受习水河谷地形影响,6.21暴雨和8.11暴雨强降雨落区分别与习水河谷赤水段和习水段走向一致。
