Multi-scale analyses of wildland fire combustion processes: Large-scale field experiments – fire radiative power

The United States Department of Defense (DoD) Strategic Environmental Research and Development Program (SERDP) funded project: Multi-scale Analyses of Wildland Fire Combustion Processes in Open-canopied Forests using Coupled and Iteratively Informed Laboratory-, Field-, and Model-based Approaches (RC-2641) conducted a large-scale (management-scale) field experiment during an operational prescribed burn to quantify how atmospheric dynamics across a wide range of spatial and temporal scales affect fire propagation, energy exchange, and fuel consumption. This experiment also provided an opportunity to fully examine how combustion related processes transfer across scales of particles and simple fuel beds in the laboratory, wind tunnel, small-scale, and operational prescribed burns as instrumentation used in small-scale field experiments was embedded in this experiment. In addition, the large-scale experiment also provides data necessary for simulation and model testing of coupled atmosphere-fire behavior prediction systems (e.g., WRF-SFire, WFDS, QUIC-Fire, FIRETEC) and coupled atmosphere-canopy-smoke dispersion prediction systems (e.g., ARPS-Canopy/FLEXPART). The large-scale field experiment includes data from a heavily instrumented ~12.1 hectare (ha) management-scale fire conducted at the Silas Little Experimental Forest in the Pinelands National Reserve (PNR) on March 13, 2019. This data publication contains data collected in thirteen Krem Boxes (KB) that consisted of a dual band infrared (IR) radiometers and visible spectrum/long wave infrared camera pairs. The KB were scattered throughout the burn area at approximately 2 meters (m) above the ground pointed at the fuel beds. Data were collected at 1 hertz (Hz). The radiometric data were used to measure radiative heat fluxes, flame arrival times and persistence. In the same housing as the radiometer is a vertical flow instrument. This sensor did not produce any significant results, as the low-intensity fires in this experiment produced vertical flows lower than the threshold for detection. The visible spectrum cameras captured conventional RGB color-balanced images at 5m pixel resolution. The long wave infrared cameras captured 80 X 60 pixel images and was equipped with a neutral density filter to minimize saturation of this camera by the emission form the flames and hot background. The cameras are nearly spatially coincident and acquire images at the same time, and so can be aligned spatially and temporally.Many DoD facilities utilize low intensity prescribed fire to manage hazardous fuels, restore ecological function and historic fire regimes, and encourage the recovery of threatened and endangered species in the forests they manage. Current predictive models used to simulate fire behavior during low-intensity prescribed fires (and wildfires) are empirically based, simplistic, and fail to adequately predict fire outcomes because they do not account for variability in fuel characteristics and interactions with important meteorological variables. This study used a suite of measurements at the fuel particle, fuel bed, field plot, and stand scales to quantify how variability in fuel characteristics and key meteorological factors interact to drive fire behavior during low intensity prescribed burns. These experiments were designed to inform the development and evaluation of mechanistic, physics-based models that explicitly account for combustion, turbulent transfer, and energy exchange by coupling and scaling individual component processes. These datasets provide measurements to improve the understanding of, and ability to accurately predict, fire behavior under a wide range of management scenarios.A summary of the SERDP Project RC-2641 can be found at the RC-2641 Project Overview (serdp-estcp.org): https://www.serdp-estcp.org/projects/details/a4a4642d-f2be-4e52-b678-454fe06afbc2/rc-2641-project-overview. Please reference the burn layout and documentation data publication (Gallagher et al. 2023, https://doi.org/10.2737/RDS-2022-0089) as these data provide the sensor locations of each burn, a detailed description of data collected and a summary of the conditions during the burn periods.美国国防部（United States Department of Defense, DoD）战略环境研究与发展计划（Strategic Environmental Research and Development Program, SERDP）资助的项目：开阔林分野火燃烧过程多尺度分析：采用耦合迭代方法结合实验室、现场与模型研究手段（RC-2641），于一次作业性计划烧除（prescribed burn）中开展了大尺度（经营尺度）野外实验，旨在量化不同时空尺度下的大气动力学如何影响火灾蔓延、能量交换与可燃物消耗。 本实验还提供了全面研究燃烧相关过程在颗粒、简单可燃物床层多尺度间传递规律的契机——由于小型野外实验所用的仪器被嵌入本次实验，研究覆盖了实验室、风洞、小尺度以及作业性计划烧除等多种场景。 此外，本次大尺度实验还为耦合大气-火灾行为预测系统（如WRF-SFire、WFDS、QUIC-Fire、FIRETEC）以及耦合大气-林冠-烟雾扩散预测系统（如ARPS-Canopy/FLEXPART）的模拟与模型验证提供了必要的数据支撑。 本次大尺度野外实验的数据源自2019年3月13日在松树岭国家保护区（Pinelands National Reserve, PNR）塞拉斯·利特尔实验林开展的、布设了大量传感设备的约12.1公顷（hectare, ha）经营尺度火烧事件。 本数据集包含13个Krem盒（Krem Box, KB）采集的数据，该设备搭载双波段红外（infrared, IR）辐射计与可见光/长波红外相机组合。 Krem盒被分散布置在整个火烧区域内，安装高度距地面约2米（meter, m），朝向可燃物床层。数据采集频率为1赫兹（hertz, Hz）。辐射计数据被用于测量辐射热通量、火焰到达时间与持续时长。 与辐射计同壳体的还有一套垂直流测量仪器，但该传感器未产生有效数据——因为本次实验的低强度火灾产生的垂直气流低于检测阈值。 可见光相机以5米每像素的分辨率采集常规RGB色彩平衡图像；长波红外相机采集80×60像素的图像，并配备中性密度滤镜以减轻火焰与高温背景的辐射对相机的饱和干扰。 两台相机的空间位置几乎重合且同步采集图像，因此可进行精准的时空配准。 许多美国国防部设施会利用低强度计划烧除来管理危险可燃物、恢复生态功能与历史火制度，促进其所经营森林中受威胁与濒危物种的恢复。 当前用于模拟低强度计划烧除（及野火）期间火灾行为的预测模型均基于经验，结构简单，且无法充分预测火灾结果——因为它们未考虑可燃物特征的变异性以及与关键气象变量的相互作用。 本研究采用一套覆盖可燃物颗粒、可燃物床层、样地以及林分尺度的测量手段，量化可燃物特征变异性与关键气象因子如何相互作用，驱动低强度计划烧除期间的火灾行为。 本实验的设计目标是，通过耦合并缩放各独立组分过程，为机械性、基于物理原理的模型开发与评估提供依据——这类模型可显式考虑燃烧、湍流输送与能量交换过程。 本数据集可为加深对多种经营场景下火灾行为的理解，并提升其精准预测能力提供实测支撑。 关于SERDP项目RC-2641的概述可查阅RC-2641项目概览页面（serdp-estcp.org）：https://www.serdp-estcp.org/projects/details/a4a4642d-f2be-4e52-b678-454fe06afbc2/rc-2641-project-overview。 请引用火烧布局与文档数据集（Gallagher等人，2023，https://doi.org/10.2737/RDS-2022-0089），该文档提供了各火烧事件的传感器布设位置、采集数据的详细描述以及火烧期间的条件总结。