Death of an ice sheet
Death of an ice sheet
复制标题
冰原的死亡
作者：
D. Lindstrom;D. Macayeal
SIR-Cahoon等人1说明卫星在绘制夜间草地或森林火灾地图方面的用途。使用的波长带为0.4-1.1！LiD，其跨越光谱的可见光和非常近的红外部分。城市的照明被它们的持久性所淘汰，火持续时间很短。只存档了照片，而不是基本的数字信息。使用的卫星是国防气象卫星计划（DMSP）Block 5的一颗，有效分辨率约为2.7公里。美国国家海洋和大气管理局（NOAA）的常规气象卫星原则上似乎更适合这项任务，因为地球的每一部分每24小时都要经过两次，一次在正午阳光下，一次在夜晚。日照强度最大值为0.5！！Ill（对应于6，000 K的温度），地球的辐射最大，大约是红热的5或10倍。但是一个面积只有20 x20米的火焰，在明亮的阳光下会比1平方公里的普通领土更亮，在晚上也会看起来很亮，而城市照明是11.0！liD（300 K）。这两个发射光谱在波长约为4 λ时以最大值的约四十分之一的强度交叉。liD，精确值取决于排放温度和其他因素。卫星A在格林尼治时间13时46分经过NOAA-9。1985年9月12日，如通过通道3波段所看到的，其也在水蒸气窗口中。可以看到英格兰农场在收获后焚烧剩余秸秆的火灾。其他更常见的热点也被记录下来，如敦刻尔克和斯肯索普的钢铁厂，以及北海平台上的耀斑。但是城市地区在夜间并不像在可见波段那样出现（见参考文献2）。
SIR-Cahoon et a/. 1 illustrate the use of a satellite in mapping grass or forest fires at night. The wavelength band used was 0.4-1.1!-liD, which spans the visible and very near infrared part of the spectrum. The illumination of cities was eliminated by their permanence, fires being of short duration. Only photographic prints, and not the basic digital information, were archived. The satellite used was one of the Defense Meteorological Satellite Program (DMSP) Block 5, with an effective resolution of about 2.7 km. Routine National Oceanic and Atmospheric Administration (NOAA) meteorological satellites seem more suitable in principle for this task, for every part of the Earth is traversed twice every 24 hours, in midday sunshine and at night. The intensity of sunshine is a maximum at 0.5!! ill (corresponding to a temperature of 6,000 K) and the Earth's emission has a maximum at about be 5 or 10 times as strong as red heat. But a flame with an area of only 20x20 m will outshine I km2 of ordinary territory in bright sunshine and will be seen as very bright at night, while urban illumination is11.0!-liD (300 K). These two emission spectra cross over with an intensity of about one-fortieth of the maximum at a wavelength of about 4!-liD, the precise values depending on the emission temperatures and other factors. The satelliteA pass by NOAA-9 at 13.46 GMT. 12 September 1985, as seen by the channel 3 waveband, which is also in a water vapour window. Fires in which surplus straw is being burned on the farms of England after the harvest can be seen. Other, more regular hotspots are also recorded, such as steel works in Dunquerque and Scunthorpe, and flares on North Sea platforms. But urban areas do not show up at night as they would in a visible waveband (see ref. 2).