基于ETM+影像的棉花低温冷害遥感监测方法研究

The Remote Sensing Monitoring Method Analysis of Cold Damage Cotton Based on ETM+ Images

为了能及时、大范围地遥感监测棉花的低温冷害状况,以便安排救灾及灾后评估,应用棉花影像特征参量及植被指数变化分析的方法,对2001年7月25日和2001年8月10日ETM+数据,经过几何校正、辐射校正、行星反射率转化等,分别形成基于DN值、辐亮度、行星反射率的NDVI,分析2001年7月28日—2001年8月1日强低温入侵前后棉田的影像参量及光谱特征变化情况。结果表明,受害前影像的DN值、辐亮度、行星反射率均值比受害后影像分别高出了29.07%、30.1%、3.15%,在方差方面,受害前各物理量的方差值均大于受害后的值,分别高出了67.5%、40.3%、33.3%,而NDVI均值下降的幅度分别为21.6%、19.57%、12.79%。高分辨率遥感影像数据可以间接反演出受低温冷害棉田的变化情况,可以作为监测强低温冷害的一种有效方法,对于灾害评估提供了定量化指标。

In order to timely monitor the cold damage conditions of cotton by remote sensing,arrange disaster relief and assessment,cotton image characteristic parameter and vegetation index change were analyzed.Applied July 25,2001 and August 10,2001 ETM＋data,the NDVI of DN values,radiance and planetary reflectance were formed through the geometric correction,radiometric correction and conversion of planetary reflectivity.Then,the cotton field characteristic parameter and spectral signatures change situation were analyzed on July 28,2001 to August 1,2001.The results showed that the previous image of the DN value,radiance,mean planetary albe do were higher than that of the subsequent image 29.07%,30.1%,3.15%,the previous image physical quantities were larger 67.5%,40.3%,33.3%than the subsequent image in the variance,while the values of mean NDVI decreased 21.6%,19.57%,12.79%.High-resolution remote sensingdata can be indirectly affected by low-temperature injury changes in cotton fields.It is an effective method to monitor the strong low-temperature injury and provide quantitative indexes for disaster assessment.