The low frequency oscillation in both hemispheres and its possible role in the dust weather storm events over North China in 2002 are analyzed as a case study. Results show that the Aleutian Low is linked with the Cir...The low frequency oscillation in both hemispheres and its possible role in the dust weather storm events over North China in 2002 are analyzed as a case study. Results show that the Aleutian Low is linked with the Circumpolar Vortex in the Southern Hemisphere on a 30-60-day oscillation, with a weak Circumpolar Vortex tending to deepen the Aleutian Low which may be helpful for the generation of dust storm events. The possible mechanism behind this is the inter-hemispheric interaction of the mean meridional circulation, with the major variability over East Asia. The zonal mean westerly wind at high latitudes of the Southern Hemisphere in the upper level troposphere may lead that of the Northern Hemisphere, which then impacts the local circulation in the Northern Hemisphere. Thus, the low frequency oscillation teleconnection is one possible linkage in the coupling between the Southern Hemisphere circulation and dust events over North China. However, the interannual variation of the low frequency oscillation is unclear.展开更多
An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the l...An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.展开更多
21世纪以来,连续波形的自动处理成为数字地震台网的一个新的前沿领域。本文通过深低频脉动(LFT,Low Frequency Tremor)、噪声相关函数(NCF,Noise Correlation Function)、"重复地震"等3个方面,指出在这一新的前沿领域中,中国...21世纪以来,连续波形的自动处理成为数字地震台网的一个新的前沿领域。本文通过深低频脉动(LFT,Low Frequency Tremor)、噪声相关函数(NCF,Noise Correlation Function)、"重复地震"等3个方面,指出在这一新的前沿领域中,中国数字地震观测系统正面临巨大的发展机遇。与此相应,在中国地震台网的下一步发展中,应重视连续波形的记录,并将连续波形的自动处理作为一个发展重点来考虑。展开更多
深低频脉动(Deep Low Frequency Tremor,即LFT)的观测近年来引起地震科学界的关注,相关的观测和研究在地震机理和地震预测预报的探索中显示出重要的应用价值。随着中国数字地震观测网络的建设和完善,通过常规地震观测对板块内部和碰撞...深低频脉动(Deep Low Frequency Tremor,即LFT)的观测近年来引起地震科学界的关注,相关的观测和研究在地震机理和地震预测预报的探索中显示出重要的应用价值。随着中国数字地震观测网络的建设和完善,通过常规地震观测对板块内部和碰撞型板块边界地区LFT是否存在、(如果存在则)是否具有普遍性、是否与间歇性地震脉动与滑动(Epidemic Tremor and Slip,即ETS)相联系等问题进行系统的调查研究,在技术上已逐步成为可能。为此,本文讨论了目前用数字地震观测系统进行LFT观测的现状和方法,并对将LFT的系统调查引入中国数字地震观测系统的常规观测提出操作建议。展开更多
基金This research was jointly supported by the Chinese Academy of Sciences key program under Crant KZCX3-SW-221the National Natural Science Foundation of China under Grant Nos.40125014 and 40475037.
文摘The low frequency oscillation in both hemispheres and its possible role in the dust weather storm events over North China in 2002 are analyzed as a case study. Results show that the Aleutian Low is linked with the Circumpolar Vortex in the Southern Hemisphere on a 30-60-day oscillation, with a weak Circumpolar Vortex tending to deepen the Aleutian Low which may be helpful for the generation of dust storm events. The possible mechanism behind this is the inter-hemispheric interaction of the mean meridional circulation, with the major variability over East Asia. The zonal mean westerly wind at high latitudes of the Southern Hemisphere in the upper level troposphere may lead that of the Northern Hemisphere, which then impacts the local circulation in the Northern Hemisphere. Thus, the low frequency oscillation teleconnection is one possible linkage in the coupling between the Southern Hemisphere circulation and dust events over North China. However, the interannual variation of the low frequency oscillation is unclear.
基金supported by the Special Scientific Research Projects for Public Interest(No.GYHY201006021 and GYHY201106016)the National Natural Science Foundation of China(No.41205040 and 40930952)
文摘An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.
文摘21世纪以来,连续波形的自动处理成为数字地震台网的一个新的前沿领域。本文通过深低频脉动(LFT,Low Frequency Tremor)、噪声相关函数(NCF,Noise Correlation Function)、"重复地震"等3个方面,指出在这一新的前沿领域中,中国数字地震观测系统正面临巨大的发展机遇。与此相应,在中国地震台网的下一步发展中,应重视连续波形的记录,并将连续波形的自动处理作为一个发展重点来考虑。
文摘深低频脉动(Deep Low Frequency Tremor,即LFT)的观测近年来引起地震科学界的关注,相关的观测和研究在地震机理和地震预测预报的探索中显示出重要的应用价值。随着中国数字地震观测网络的建设和完善,通过常规地震观测对板块内部和碰撞型板块边界地区LFT是否存在、(如果存在则)是否具有普遍性、是否与间歇性地震脉动与滑动(Epidemic Tremor and Slip,即ETS)相联系等问题进行系统的调查研究,在技术上已逐步成为可能。为此,本文讨论了目前用数字地震观测系统进行LFT观测的现状和方法,并对将LFT的系统调查引入中国数字地震观测系统的常规观测提出操作建议。
