飑线天气过程对云南洞体应变干扰的特征与机制

Unique imprint and causal mechanism of extensometer in response to a propagating squall line in Yunnan Province,China

2016年4月19日云南地区爆发了一次强飑线天气,并相继对楚雄和昆明台的洞体应变观测产生了显著干扰.那么其扰动的全貌和机制究竟如何?截止目前,还鲜有研究.有鉴于此,本文结合多普勒天气雷达和地面气象观测要素数据,对楚雄和昆明台洞体应变的响应历程进行了深入分析.结果表明:(1)飑线过境时的“雷暴鼻”是洞体应变呈脉冲状张性变化的主因,由此产生的最大应变量为19.04×10^(-9);(2)各台洞体应变的扰动形态与“雷暴鼻”高度相似,说明其台基岩体均能以线弹性变形的方式响应飑线过程中的气压剧变;(3)“雷暴鼻”中周期性气压的能量主要集中在8~20 cpd频段内;(4)洞体应变对“雷暴鼻”的响应存在一定的相位超前现象.以上结果,不单有助于辨识云南地区洞体应变时序曲线中飑线噪声,而且还能为高频段气压效应的精确改正等提供观测证据.

On 19 April 2016,a southwest-northeast-oriented squall line was observed propagating across Yunnan Province.A pulse-like disturbance traveling across the Chuxiong and the Kunming stations was recorded with extensometers.However,the imprint and causal mechanism of this pulse-like strain wave is still yet to be uncovered.By combining Doppler radar observations,surface atmospheric pressure data,air temperature data,and rainfall data,we systematically analyze the pulse-like disturbances at the Chuxiong and the Kunming stations induced by the squall line.The results show that:(1)The pulse-like extensional strain is determined to be pressure nose in origin,and the pressure-induced extensional strain can reach up to 19.04×10^(-9);(2)The disturbed strain data are compared with atmospheric pressure fluctuations,and a good correlation is found,this phenomenon indicates that the rock media in the observatory areas have good elastic properties;(3)The energy of periodic waves in the pressure nose is concentrated mainly in the 8~20 cpd frequency band;(4)Comparing to the phase of pressure nose,a small phase advance of the pulse-like strain signal is clearly observed.The obtained results can help to better identify the noise derived from squall line.Furthermore,the derived parameters are useful constraints for precise atmospheric correction.