Remote sensing to detect sub-surface peat fires and peat fire scars in the Okavango Delta, Botswana : research article

Remote sensing to detect sub-surface peat fires and peat fire scars in the Okavango Delta, Botswana : research article
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遥感探测博茨瓦纳奥卡万戈三角洲的地下泥炭火灾和泥炭火痕：研究文章

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发表时间：
2002
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通讯作者：
K. Wessels
K. Wessels
中科院分区：
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文献类型：
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作者：
T. Gumbricht;T. McCarthy;J. McCarthy;D. Roy;P. Frost;K. Wessels

文献摘要

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由于不断变化的水分布在 奥卡万戈三角洲，博茨瓦纳，泥炭堆积在前湿地 邻近后退通道的地方被连续的大火烧毁， 随着泥炭的干燥而分层。燃烧泥炭的记录 自世纪中期以来，围绕着濒临消亡的塔格海峡。在这 在一项研究中，五种不同的遥感器被用来探测 以及奥卡万戈三角洲附近ATSR数据被用来研究 1999 - 2000年，AVHRR数据和MODIS数据， 用于监测2000年火灾季节， 模拟器和Landsat ETM数据用于高分辨率 研究单一火灾事件。泥炭火灾被发现使用 中红外光谱中的绝对阈值， 在中红外和热红外亮度温度之间， 阈值在可见光到近红外光谱。下限阈值 必须采用比通常使用的更先进的方法来探测火灾， 对其他地区的火灾估计过高。机载MODIS 模拟器成功识别了泥炭火灾的状态。利用 一个标准的固定阈值，活跃的火灾探测算法， ATSR、AVHRR和中分辨率成像分光仪数据只发现了强烈的地表火。 泥炭火灾只能通过使用lIgprioril/IG知识来区分， 空间分布或时间历史。Landsat ETM数据 不能用来探测这些火灾。泥炭火灾 年周期，在干燥的冬季达到最大值，与 地表火灾季节，潮湿的夏季处于休眠状态。 夜间图像对于探测地下火灾是必要的。的 奥卡万戈目前的泥炭火灾面积约为100平方公里， 预计对区域跟踪的贡献可以忽略不计， 气体和微粒排放。
As a consequence of the constantly shifting water distribution in the Okavango Delta, Botswana, peat accumulated in former wetlands adjacent to receding channels is consumed by fire in successive layers as the peat desiccates. Burning peat has been recorded around the dying Thaoge channel since themid-19th century. In this study, five different remote sensors were used to detect peat fires in and around the Okavango Delta. ATSR data were used to study the annual cycle from 1999 to 2000, AVHRR data and MODIS data were used to monitor the 2000 fire season, and the MODIS Airborne Simulator and Landsat ETM data were employed for high-resolution studies of single fire events. Peat fires were detected using absolute thresholds in the mid-infrared spectrum, the difference between mid and thermal infrared brightness temperatures, and a threshold in the visible to near-infrared spectrum. Lower thresholds than normally used had to be adopted to detect the fires, which led to an overestimation of fires over other areas. The MODIS Airborne Simulator successfully identified the state of peat fires. Making use of a standard fixed threshold, active-fire detection algorithms, ATSR, AVHRR and MODIS data identified only intense surface fires. Peat fires were distinguished only by using a lIgprioril/Ig knowledge of either spatial distributions or temporal history. Landsat ETM data could not be used to detect these fires. The peat fires have an annual cycle, with a maximum during the dry winter, coinciding with the surface fire season, and a dormant state during the wet summer. Night-time imagery was necessary to detect sub-surface fires. The present area of peat fires in the Okavango is approximately 100km2, which is expected to make negligible contributions to regional trace gas and particulate emissions.