Unique imprint and causal mechanism of extensometer in response to a propagating squall line in Yunnan Province,China
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.
NETL
NSTL
万方数据
