Addressing the spatiotemporal sampling design of MODIS to provide estimates of the fire radiative energy emitted from Africa
Addressing the spatiotemporal sampling design of MODIS to provide estimates of the fire radiative energy emitted from Africa
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DOI：
10.1016/j.rse.2010.09.017
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发表时间：
2011-02-15
影响因子：
13.5
通讯作者：
Roberts, Gareth
中科院分区：
文献类型：
--
作者：
Freeborn, Patrick H.;Wooster, Martin J.;Roberts, Gareth
基于卫星的对开放式生物质燃烧产生的火辐射功率(FRP)和能量(FRE)的估计受到极轨和地球静止传感器时空分辨率的影响。在这里，MODIS抽样设计对FRE估计的影响的特征是将Terra和Aqua颗粒的时间和范围叠加到SEVIRI活性火灾产品上。非洲不同土地覆盖类型的结果表明，SEVIRI在8天内测量的FRE与SEVIRI在MODIS颗粒中测量的FRP总和是线性相关的。这些关系在火灾季节的高峰期变化最小，此时SEVIRI测量的玻璃钢的日循环最一致。FRE和使用SEVIRI活动火灾产品开发的FRP总和之间的关系被直接应用于从MODIS Terra和Aqua气候模拟网格(CMG)火灾产品中提取的FRP总和。本文从MODIS获得的FRE估计值与由先前公布的方法获得的估计值在5%以内，但仍是通过调整FRE的SEVIRI测量值以解决低空间分辨率检测偏差而获得的0.72倍的系数。对MODIS扫描几何结构的研究表明，后者被低估是由于MOWS成像伪影(称为“蝴蝶结”效应)和用于从MODIS CMG火灾产品中提取FRP总和的典型计算之间的耦合。根据MODIS扫描角信息的可用性，我们提供了严格和简化的计算来解释领结效应。将简化的调整应用于MODIS CMG火灾产品，得到的全国月度FRE估计是最初预测的1.44倍。(C)2010 Elsevier Inc.保留所有权利。
Satellite-based estimates of the fire radiative power (FRP) and energy (FRE) emitted from open biomass burning are affected by the spatiotemporal resolution of polar-orbiting and geostationary sensors. Here the impacts of the MODIS sampling design on estimates of FRE are characterized by superimposing the timing and extents of the Terra and Aqua granules onto the SEVIRI active fire product. Results for different land-cover types across Africa indicate that the FRE measured by SEVIRI during eight days is linearly related to the sum of FRP measured by SEVIRI within the MODIS granules. These relationships are least variable during the height of the fire season when diurnal cycles of FRP measured by SEVIRI are most consistent. Relationships between FRE and the sum of FRP developed using the SEVIRI active fire product are directly applied to the sum of FRP retrieved from the MODIS Terra and Aqua Climate Modeling Grid (CMG) fire products. Estimates of FRE from MODIS herein agree within 5% of those obtained from previously published methods, but remain a factor of 0.72 times those obtained by adjusting SEVIRI measurements of FRE to account for low spatial resolution detection biases. An examination of the MODIS scan geometry suggests that the latter underestimation is attributed to the coupling between a MOWS imaging artefact referred to as the "bow-tie" effect and the typical calculation used to retrieve the sum of FRP from the MODIS CMG fire products. Depending on the availability of MODIS scan angle information, we offer rigorous and simplified calculations to account for the bow-tie effect. Applying the simplified adjustment to the MODIS CMG fire products yields national estimates of monthly FRE that are 1.44 times greater than originally predicted. (C) 2010 Elsevier Inc. All rights reserved.