摘要
本文通过涡度方法、时频分析等方法,研究了岷县漳县6.6级地震前,震中区域(102.50°E^105.50°E,33.50°N^37.50°N)红外遥感OLR时空分布特征,结果显示:(1)岷县漳县6.6级地震前震中区域涡度场存在显著增强的异常现象;(2)震中区格点OLR涡度值时序曲线一般情况下随机波动,但在震前存在明显异常变化,其时频结果也显示在地震前存在能量密度增强现象,异常期间谱结构不断变化。
Outgoing Long-wave Radiation （OLR）,also known as thermal radiant flux density,refers to the energy density of electromagnetic waves emitted by the earth-atmosphere system into outer space.OLR is the broadband （5～50 μm） information that forms after reprocessing of the telemetry data of a single infrared band.The dataset adopted in this study is the evening data of the National Oceanic and Atmospheric Administration （NOAA） OLR satellite networking with a resolution of 1 ° × 1 ° in which the unit is W/m2.Such information appears on the NOAA Website at ftp：//ftp.cpc.noaa.gov.In this study,the eddy method and time-frequency analysis are used to examine the temporal and spatial distribution characteristics of Outgoing Longwave Radiation （OLR） in the epicenter area of the Minxian-Zhangxian MS6.6 earthquake （102.50° E-105.50° E,33.50°N-37.50° N） determined by infrared remote sensing.Results indicate that an enhancement of the monthly average of the eddy field of the OLR did not appear in the corresponding period between 2009 and 2012.The time series curve of the OLR eddy monthly average,in the epicenter grid points （103.50°E,35.50°N）,（104.50°E,34.50°N） of the earthquake,showed was no significant seasonal variation in the OLR eddy value.Generally,the eddy value fluctuated randomly near the average value line.Prior to the earthquake,however,the value showed abnormal and distinct short-term changes.To examine these change characteristics,the short-time Fourier transform method was used to determine the time-frequency analysis of the daily eddy value of the grid points （103.50°E,35.50°N）.The results indicate that prior to the earthquake,an unusual increase in energy density occurred.During the abnormal period,the characteristics of the spectral structure changed.The low-frequency components were principal in the early stage,whereas the radio-frequency component became the principal part during the later stage.Previous research identified an abnormal increase in OLR informatio
出处
《地震工程学报》
CSCD
北大核心
2013年第4期794-799,共6页
China Earthquake Engineering Journal
基金
地震行业科研专项经费项目(201208009)
震情跟踪课题(2012020406)
关键词
岷县漳县6
6级地震
长波辐射
涡度
异常变化
Minxian-Zhangxian MS6.6 earthquake
Outgoing Long-wave Radiation
eddy
abnormality
