基于FY-3D/MERSI-II远红外数据的火情监测研究

风云三号D极轨气象卫星中分辨率成像光谱仪(FY-3D/MERSI-Ⅱ)具有250 m分辨率的10. 8μm和12μm波长的远红外通道,为气象卫星遥感火情应用提供更为丰富的数据源。文章研究了FY-3D/MERSI-Ⅱ的10. 8μm远红外通道监测火情的特点,10. 8μm远红外通道虽在光谱方面对高温热源探测灵敏度不如FY-3D/MERSI-Ⅱ的3. 8μm中红外通道,但由于空间分辨率较1 km分辨率的中红外通道高4倍,因而对较大的火点有明显反映,火点探测能力较1 km分辨率远红外通道有明显提高。利用混合像元线性波谱分离方法计算,对于平均温度为750 K,面积400 m^2的明火区,在1 km分辨率远红外通道像元引起的亮温增量约0. 47 K,而在250 m分辨率远红外通道像元引起的亮温增量约为7. 30 K,可与周边背景像元亮温形成较明显差异。利用1 km分辨率的中红外通道判识火点范围,利用250 m分辨率的远红外通道进一步确定明火区位置,可将火点定位精度从公里级提高到百米级。利用该方法开展了森林草原火灾应用实例分析,基于250 m分辨率远红外通道确定的火点位置与实地考察信息吻合较好,说明了提出方法的有效性。多个应用实例表明,在反映大范围火场中较强火势区域位置和草原火灾明火线分布等方面,FY-3D/MERSI-Ⅱ远红外通道较中红外通道具有明显优势,可以更加精细化和准确的反映火情的空间分布,在火情监测方面具有实际应用价值。

Fire monitoring based on FY-3D/MERSI-II far-infrared data

FY-3D/MERSI-II polar orbiting meteorological satellite has 250 m resolution in 10.8 and 12μm wavelengths of far-infrared channels,which provide more abundant data sources for fire monitoring.The characteristics of fire monitoring in FY-3D/MERSI-II 10.8μm far-infrared channel were studied.Although 10.8μm far-infrared channel is far less sensitive than FY-3D/MERSI-II's 3.8μm mid-infrared channel in the spectral aspect to high-temperature heat source detection,its spatial resolution is 4 times higher than that of 1 km mid-infrared channel,so it can clearly reflect larger fire points,and its fire detection ability is better than that of 1 km resolution far-infrared channel.There has been a marked improvement.Using mixed pixel linear spectral separation method,the brightness temperature increment caused by the open fire area with an average temperature of 750 K and an area of 400 m2 in far infrared channel pixels at 1 km resolution is about 0.47 K,while that caused by the same fire condition in far infrared channel pixels at 250 m resolution is about 7.30 K,which is quite different from the brightness temperature of surrounding background pixels.The fire location accuracy can be improved from kilometer level to hundreds meter level by using 1 km resolution mid-infrared channel to identify the fire range and 250 m resolution far-infrared channel to further determine the open fire area.Based on the method proposed in this paper,an example of forest and grassland fire application is analyzed.The location of fire point determined by 250 m resolution far-infrared channel is in good agreement with the field investigation information,which shows the effectiveness of the proposed method.Several application examples showed that the FY-3D/MERSI far-infrared channel has obvious advantages over the mid-infrared channel in reflecting the location of the intense fire area and the distribution of the open fire line of grassland fire in large-scale fire field.It can reflect the spatial distribution of wildfire more accurately,so it has application value in fire monitoring.