利用NCEP 1°×1°再分析资料、常规气象观测资料、降雪加密观测资料和卫星云图资料,对2014年2月17—19日杭州地区一次雨转雪天气过程进行了分析。结果表明:500 h Pa南支槽、700 h Pa和850 h Pa切变线,配合700 h Pa西南急流...利用NCEP 1°×1°再分析资料、常规气象观测资料、降雪加密观测资料和卫星云图资料,对2014年2月17—19日杭州地区一次雨转雪天气过程进行了分析。结果表明:500 h Pa南支槽、700 h Pa和850 h Pa切变线,配合700 h Pa西南急流,为杭州地区此次雨转雪天气过程提供了较好的动力抬升和水汽条件;而700 h Pa暖湿气流与850 h Pa不断增强的东北气流,又为此次雨转雪天气过程提供了上暖下冷的有利层结条件。此次雨雪天气过程水汽通量与降水时段和降水强度对应。整个雨转雪天气过程中对流层均以垂直上升运动为主,相对湿度均较大,且降水不同阶段均存在水汽辐合;液态降水时,对流层中低层为水汽辐合层和上升运动层,且中层存在辐散抽吸作用,此配置有利于产生降水;而当降雪时,中低层的水汽辐合与垂直上升速度逐渐减小,此时以中层的水汽辐合和上升运动为主。雨雪强度减弱时,水汽辐合也减弱直至消失,且中低层和中层的上升速度均逐渐减弱,在600 h Pa附近出现弱下沉运动和相对湿度迅速减小的现象,但中低层一直维持弱的上升运动与较大的相对湿度,直至19日凌晨雨雪过程才结束。由于此次雨转雪天气过程冷空气较弱,地面温度相对较高,因此降水量虽然较大,但积雪率较低。展开更多
为实现4D(时间+空间)多目标、高精度的积雪监测,本次试验研究采用单台相机延时拍摄结合运动结构重建算法(Structure from motion,SfM),分别获取了祁连山黑河上游站裸露山坡坡面尺度单次降雪的雪深、逐日积雪空间分布和面积,以及祁连山...为实现4D(时间+空间)多目标、高精度的积雪监测,本次试验研究采用单台相机延时拍摄结合运动结构重建算法(Structure from motion,SfM),分别获取了祁连山黑河上游站裸露山坡坡面尺度单次降雪的雪深、逐日积雪空间分布和面积,以及祁连山八一冰川1.5m×1.5m的斑块尺度全年雪深及雪面特征数据。坡面尺度积雪观测研究表明:本方法可以准确获取积雪分布信息,但其雪深空间分布获取精度较差。斑块尺度雪深监测研究表明:本方法能够很好地获取连续的雪面特征信息和雪深,且获取雪深与SR50观测雪深的绝对误差小于3.4cm。在不同季节,本方法对积雪监测能力略有差异:春季快速积累期雪面纹理少,照片组对齐并获取点云数据和DEM数据的成功率较低,而冬季和消融季雪面纹理丰富,相应的对齐成功率比例和精度较高。本研究表明基于单台相机的4D摄影测量方法能够实现小范围、连续、高精度、多目标的积雪监测,未来应用前景广泛。展开更多
Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely coupled.In this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of me...Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely coupled.In this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of meteorological and sea ice conditions during the ice season of 2018-2019 relative to climatological means using a Lagrangian methodology.We obtained the anomalies along the drifting trajectories of eight sea ice mass balance buoys between the marginal ice zone and the pack ice zone in the western Arctic Ocean(~160°W-170°W and 79°N-85°N)from September 2018 toAugust 2019.The temporary collapse of the Beaufort High and a strong positive Arctic Dipole in the winter of 2018-2019 drove the three buoys in the north to drift gradually northeastward and merge into the Transpolar Drift Stream.The most prominent positive temperature anomalies in 2018-2019 along the buoy trajectories relative to 1979-2019 climatology occurred in autumn,early winter,and April,and were concentrated in the southern part of the study area;these anomalies can be partly related to the seasonal and spatial patterns of heat release from the Arctic ice-ocean system to the atmosphere.In the southern part of the study area and in autumn,the sea ice concentration in 2018-2019 was higher than that averaged over the past 10 years.However,we found no ice concentration anomalies for other regions or seasons.The sea ice thickness in the freezing season and the snow depth by the end of the winter of 2018-2019 can also be considered as normal.Although the wind speed in 2018-2019 was slightly lower than that in 1979-2019,the speed of sea ice drift and its ratio to wind speed were significantly higher than the climatology.In 2019,the sea ice surface began to melt at the end of June,which was close to the 1988-2019 climatology.However,spatial variations in the onsets ofsurface melt in 2019 differed from the climatology,and can be explained by the prevalence of a high-pressure system in the south of the Beaufort Sea in June 2019.In addition to seasonal variations,the meteorological and sea ice anomalies were influenced by spatial variations.By the end of summer 2019,the buoys had drifted to the west of the Canadian Arctic Archipelago,where the ice conditions was heavier than those at the buoy locations in early September 2018.The meteorological and sea ice anomalies identified in this study lay the foundations for subsequent analyses and simulations of sea ice mass balance based on the buoy data.展开更多
文摘利用NCEP 1°×1°再分析资料、常规气象观测资料、降雪加密观测资料和卫星云图资料,对2014年2月17—19日杭州地区一次雨转雪天气过程进行了分析。结果表明:500 h Pa南支槽、700 h Pa和850 h Pa切变线,配合700 h Pa西南急流,为杭州地区此次雨转雪天气过程提供了较好的动力抬升和水汽条件;而700 h Pa暖湿气流与850 h Pa不断增强的东北气流,又为此次雨转雪天气过程提供了上暖下冷的有利层结条件。此次雨雪天气过程水汽通量与降水时段和降水强度对应。整个雨转雪天气过程中对流层均以垂直上升运动为主,相对湿度均较大,且降水不同阶段均存在水汽辐合;液态降水时,对流层中低层为水汽辐合层和上升运动层,且中层存在辐散抽吸作用,此配置有利于产生降水;而当降雪时,中低层的水汽辐合与垂直上升速度逐渐减小,此时以中层的水汽辐合和上升运动为主。雨雪强度减弱时,水汽辐合也减弱直至消失,且中低层和中层的上升速度均逐渐减弱,在600 h Pa附近出现弱下沉运动和相对湿度迅速减小的现象,但中低层一直维持弱的上升运动与较大的相对湿度,直至19日凌晨雨雪过程才结束。由于此次雨转雪天气过程冷空气较弱,地面温度相对较高,因此降水量虽然较大,但积雪率较低。
文摘为实现4D(时间+空间)多目标、高精度的积雪监测,本次试验研究采用单台相机延时拍摄结合运动结构重建算法(Structure from motion,SfM),分别获取了祁连山黑河上游站裸露山坡坡面尺度单次降雪的雪深、逐日积雪空间分布和面积,以及祁连山八一冰川1.5m×1.5m的斑块尺度全年雪深及雪面特征数据。坡面尺度积雪观测研究表明:本方法可以准确获取积雪分布信息,但其雪深空间分布获取精度较差。斑块尺度雪深监测研究表明:本方法能够很好地获取连续的雪面特征信息和雪深,且获取雪深与SR50观测雪深的绝对误差小于3.4cm。在不同季节,本方法对积雪监测能力略有差异:春季快速积累期雪面纹理少,照片组对齐并获取点云数据和DEM数据的成功率较低,而冬季和消融季雪面纹理丰富,相应的对齐成功率比例和精度较高。本研究表明基于单台相机的4D摄影测量方法能够实现小范围、连续、高精度、多目标的积雪监测,未来应用前景广泛。
基金supported by grants from the National Key Research and Development Program (Grant no. 2021YFC2803304)the National Natural Science Foundation of China (Grant nos. 41976219 and 42106231)
文摘Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely coupled.In this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of meteorological and sea ice conditions during the ice season of 2018-2019 relative to climatological means using a Lagrangian methodology.We obtained the anomalies along the drifting trajectories of eight sea ice mass balance buoys between the marginal ice zone and the pack ice zone in the western Arctic Ocean(~160°W-170°W and 79°N-85°N)from September 2018 toAugust 2019.The temporary collapse of the Beaufort High and a strong positive Arctic Dipole in the winter of 2018-2019 drove the three buoys in the north to drift gradually northeastward and merge into the Transpolar Drift Stream.The most prominent positive temperature anomalies in 2018-2019 along the buoy trajectories relative to 1979-2019 climatology occurred in autumn,early winter,and April,and were concentrated in the southern part of the study area;these anomalies can be partly related to the seasonal and spatial patterns of heat release from the Arctic ice-ocean system to the atmosphere.In the southern part of the study area and in autumn,the sea ice concentration in 2018-2019 was higher than that averaged over the past 10 years.However,we found no ice concentration anomalies for other regions or seasons.The sea ice thickness in the freezing season and the snow depth by the end of the winter of 2018-2019 can also be considered as normal.Although the wind speed in 2018-2019 was slightly lower than that in 1979-2019,the speed of sea ice drift and its ratio to wind speed were significantly higher than the climatology.In 2019,the sea ice surface began to melt at the end of June,which was close to the 1988-2019 climatology.However,spatial variations in the onsets ofsurface melt in 2019 differed from the climatology,and can be explained by the prevalence of a high-pressure system in the south of the Beaufort Sea in June 2019.In addition to seasonal variations,the meteorological and sea ice anomalies were influenced by spatial variations.By the end of summer 2019,the buoys had drifted to the west of the Canadian Arctic Archipelago,where the ice conditions was heavier than those at the buoy locations in early September 2018.The meteorological and sea ice anomalies identified in this study lay the foundations for subsequent analyses and simulations of sea ice mass balance based on the buoy data.
