Airborne Thermal Infrared Imagery Research Articles

Can Multiscale Thermal Infrared Imaging Help Validate and Monitor Water Stress in Alluvial Forests?

ABSTRACTAlluvial forests are sensitive to drought induced by climate change and exacerbated by altered flow regimes. Our ability to detect and map their sensitivity to drought is crucial to evaluate the effects of climate change and adjust management practices. Therefore, we explore the potential of multiscale thermal infrared imagery (TIR) to diagnose their sensitivity to droughts. In summer 2022, we sampled leaves and phloem on Populus nigra trees from two sites with contrasted hydrological connectivity along the Ain River (France) to investigate the seasonality of water stress and act as ground truth for airborne TIR images. To map forest sensitivity to drought, we used TIR data from four airborne campaigns and Landsat archives over a larger spatial and temporal extent. Field data showed that stress conditions were reached for both sites but were higher in the site with lower groundwater connectivity, which was also the case for individual tree crown temperatures. At the forest plot scale, canopy temperature was linked to forest connectivity for two of four TIR campaigns, with higher values in the more degraded reaches. Landsat data were used to locate the areas of the riparian forest impacted by a historical drought event and monitor their recovery and proved useful to identify trends. TIR data showed promising results to help detect and map tree water stress in riparian environments. However, stress is not detected in all TIR campaigns, demonstrating that one‐shot TIR acquisitions alone are not enough to diagnose stress and complementary in‐field eco‐physiological measurements are necessary.

Spatial-Statistical Analysis of Landscape-Level Wildfire Rate of Spread

The objectives of this study were to evaluate spatial sampling and statistical aspects of landscape-level wildfire rate of spread (ROS) estimates derived from airborne thermal infrared imagery (ATIR). Wildfire progression maps and ROS estimates were derived from repetitive ATIR image sequences collected during the 2017 Thomas and Detwiler wildfire events in California. Three separate landscape sampling unit (LSU) sizes were used to extract remotely sensed environmental covariates known to influence fire behavior. Statistical relationships between fire spread rates and landscape covariates were analyzed using (1) bivariate regression, (2) multiple stepwise regression, (3) geographically weighted regression (GWR), (4) eigenvector spatial filtering (ESF) regression, (5) regression trees (RT), and (6) and random forest (RF) regression. GWR and ESF regressions reveal that relationships between covariates and ROS estimates are substantially non-stationary and suggest that the global association of fire spread controls are locally differentiated on landscape scales. Directional slope is by far the most strongly associated covariate of ROS for the imaging sequences analyzed and the size of LSUs has little influence on any of the covariate relationships.

Examining Landscape-Scale Fuel and Terrain Controls of Wildfire Spread Rates Using Repetitive Airborne Thermal Infrared (ATIR) Imagery

The objectives of this study are to evaluate landscape-scale fuel and terrain controls on fire rate of spread (ROS) estimates derived from repetitive airborne thermal infrared (ATIR) imagery sequences collected during the 2017 Thomas and Detwiler extreme wildfire events in California. Environmental covariate data were derived from prefire National Agriculture Imagery Program (NAIP) orthoimagery and USGS digital elevation models (DEMs). Active fronts and spread vectors of the expanding fires were delineated from ATIR imagery. Then, statistical relationships between fire spread rates and landscape covariates were analyzed using bivariate and multivariate regression. Directional slope is found to be the most statistically significant covariate with ROS for the five fire imagery sequences that were analyzed and its relationship with ROS is best characterized as an exponential growth function (adj. R2 max = 0.548, min = 0.075). Imaged-derived fuel covariates alone are statistically weak predictors of ROS (adj. R2 max = 0.363, min = 0.002) but, when included in multivariate models, increased ROS predictability and variance explanation (+14%) compared to models with directional slope alone.

Mapping groundwater discharge to a coastal lagoon using combined spatial airborne thermal imaging, radon (222Rn) and multiple physicochemical variables

AbstractCoastal lagoons are significant wetland environments found on coastlines throughout the world. Groundwater seepage may be a key component of lagoon water balances, though only a few studies have investigated large (>100 km2) coastal lagoons. In this study, we combined airborne thermal infrared imagery with continuous measurements of radon (222Rn—a natural groundwater tracer), conductivity, water temperature and dissolved oxygen to map groundwater seepage to a large coastal lagoon in New Zealand. We found evidence of seepage along the margins of the lagoon but not away from the margins. Our findings confirmed previously known seepage zones and identified new potential locations of groundwater inflow. Both point source and diffuse seepage occurred on the western and northwestern margins of the lagoon and parallel to the barrier between the lagoon and sea. These observations imply geologic controls on seepage. The combination of remote sensing and in‐situ radon measurements allowed us to effectively map groundwater discharge areas across the entire lagoon. Combined, broad‐scale qualitative methods built confidence in our interpretation of groundwater discharge locations in a large, dynamic coastal lagoon.

Investigation of submarine groundwater discharge to tidal rivers: Evidence for regional and local scale seepage

AbstractFluxes of submarine groundwater discharge (SGD) were investigated into two tidal rivers on the north and south shore of Long Island, NY, during July 2015. Ground‐based handheld thermal infrared (TIR) imagery, combined with direct push‐point piezometer sampling, documented spatially heterogeneous small‐scale intertidal seepage zones. Pore waters were relatively fresh and enriched in nitrogen (N) within these small‐scale seeps. Pore waters sampled just 20 cm away, outside the boundary of the ground‐based TIR‐located seepage zone, were more saline and lower in N. These ground‐based TIR‐identified seeps geochemically represented the terrestrial fresh groundwater endmember, whereas N in pore waters sampled outside of the TIR‐identified seeps was derived from the remineralization of organic matter introduced into the sediment by tidal seawater infiltration. A 222Rn (radon‐222) time‐series was used to quantify fresh SGD‐associated N fluxes using the N endmembers sampled from the ground‐based TIR pore water profiles. N fluxes were up‐scaled to groundwater seepage zones identified from high‐resolution airborne TIR imagery using the two‐dimensional size of the airborne TIR surface water anomalies, relative to the N flux from the time‐series sampling location. Results suggest that the N load from the north‐shore tidal river to Long Island Sound is underrepresented by at least 1.6–3.6%, whereas the N load from SGD to a south‐shore tidal river may be up to 9% higher than previous estimates. These results demonstrate the importance of SGD in supplying nutrients to the lower reaches of tidal rivers and suggest that N loads in other tidal river environments may be underestimated if SGD is not accounted for.

Measuring fire spread rates from repeat pass airborne thermal infrared imagery

The objective is to evaluate procedures for direct measurement of fire spread rates (FSRs) based on archived repeat pass airborne thermal infrared (ATIR) imagery and to identify requirements for more refined measurements of FSR and environmental factors that influence FSR. Flaming front positions are delineated on sequential FireMapper ATIR images captured at relatively short repeat intervals enabling fire spread vectors and units to also be delineated. This approach provides the only means for estimating FSR for wildfires at spatial scales in the order of 101–103 m and timescales from 102 to 105 s. Magnitudes of estimated FSR from the time sequential ATIR approach for the 2002 Williams fire in southern California tested here are reasonable, given the fire conditions are within the range of rates reported in the literature for wildland fires in Mediterranean shrublands.

Using airborne thermal infrared imagery and helicopter EM conductivity to locate mine pools and discharges in the Kettle Creek watershed, north-central Pennsylvania

The Kettle Creek watershed contains 50–100-year-old surface and underground coal mines that are a continuing source of acid mine drainage (AMD). To characterize the mining-altered hydrology of this watershed, an airborne reconnaissance was conducted in 2002 using airborne thermal infrared imagery (TIR) and helicopter-mounted electromagnetic (HEM) surveys. TIR uses the temperature differential between surface water and groundwater to locate areas where groundwater emerges at the surface. TIR anomalies located in the survey included seeps and springs, as well as mine discharges. In a follow-up ground investigation, hand-held GPS units were used to locate 103 of the TIR anomalies. Of the sites investigated, 26 correlated with known mine discharges, whereas 27 were previously unknown. Seven known mine discharges previously obscured from TIR imagery were documented. HEM surveys were used to delineate the groundwater table and also to locate mine pools, mine discharges, and groundwater recharge zones. These surveys located 12 source regions and flow paths for acidic, metal-containing (conductive) mine drainage; areas containing acid-generating mine spoil; and areas of groundwater recharge and discharge, as well as identifying potential mine discharges previously obscured from TIR imagery by nondeciduous vegetation. Follow-up ground-based electromagnetic surveys verified the results of the HEM survey. Our study suggests that airborne reconnaissance can make the remediation of large watersheds more efficient by focusing expensive ground surveys on small target areas.

Helicopter Frequency Domain(FDEM) Surveys for Characterizing Environmental Problems Related to Mining: Observations and Conclusions from 30 Surveys

Since 1999, the National Energy Technology Laboratory has conducted helicopter frequency domain electromagnetic (FDEM) surveys of 30 sites to identify hydrologic problems that have resulted from mining activity. The FDEM data from these surveys was processed to generate conductivity maps and conductivity/depth images (CDI), which together show the lateral and vertical distribution of ground conductivity. This information has been used to determine: 1) the location, depth, and thickness of regional water tables and perched water tables, 2) the location of infiltration zones, 3) the location of pyritic wastes either on the surface or at depth, 4) the location of flooded mine workings (if filled with conductive water and located at depths less than 50 m), and 5) the likely locations for springs or mine discharges. Helicopter FDEM results have been validated using down-hole geophysical measurements, traditional hydrologic measurements from dense networks of groundwater monitoring wells, ground-based electromagnetic surveys, airborne thermal infrared imagery, and field

Evaluation of Airborne Thermal Infrared Imagery for Locating Mine Drainage Sites in the Lower Kettle Creek and Cooks Run Basins, Pennsylvania, USA

High-resolution airborne thermal infrared (TIR) imagery data were collected over 90.6 km2 (35 mi2) of remote and rugged terrain in the Kettle Creek and Cooks Run Basins, tributaries of the West Branch of the Susquehanna River in north-central Pennsylvania. The purpose of this investigation was to evaluate the effectiveness of TIR for identifying sources of acid mine drainage (AMD) associated with abandoned coal mines. Coal mining from the late 1800s resulted in many AMD sources from abandoned mines in the area. However, very little detailed mine information was available, particularly on the source locations of AMD sites. Potential AMD sources were extracted from airborne TIR data employing custom image processing algorithms and GIS data analysis. Based on field reconnaissance of 103 TIR anomalies, 53 sites (51%) were classified as AMD. The AMD sources had low pH (<4) and elevated concentrations of iron and aluminum. Of the 53 sites, approximately 26 sites could be correlated with sites previously documented as AMD. The other 27 mine discharges identified in the TIR data were previously undocumented. This paper presents a summary of the procedures used to process the TIR data and extract potential mine drainage sites, methods used for field reconnaissance and verification of TIR data, and a brief summary of water-quality data.

Evaluation of Airborne Thermal Infrared Imagery for Locating Mine Drainage Sites in the Lower Youghiogheny River Basin, Pennsylvania, USA

Nighttime high-resolution airborne thermal infrared imagery (TIR) data were collected in the predawn hours during Feb 5-8 and March 11-12, 1999, from a helicopter platform for 72.4 km of the Youghiogheny River, from Connellsville to McKeesport, in southwestern Pennsylvania. The TIR data were used to identify sources of mine drainage from abandoned mines that discharge directly into the Youghiogheny River. Image-processing and geographic information systems (GIS) techniques were used to identify 70 sites within the study area as possible mine drainage sources. The combination of GIS datasets and the airborne TIR data provided a fast and accurate method to target the possible sources. After field reconnaissance, it was determined that 24 of the 70 sites were mine drainage. This paper summarizes: the procedures used to process the TIR data and extract potential mine-drainage sites; methods used for verification of the TIR data; a discussion of factors affecting the TIR data; and a brief summary of water quality.

Characteristics of large terrestrial impact structures as revealed by remote sensing studies

Remote sensing data sets of a spectrum of impact structures on Earth have been analyzed in an effort to determine if such structures have identifiable signatures which could be used as an aid in searching broad areas for the “missing craters” predicted by current estimates of the cratering flux. Meteor Crater, Arizona has been used as a “control” site, due to the extensive data available for this feature. Laboratory thermal infrared reflectance spectra of shocked sandstones indicate that shock processes alter the appearance of fundamental absorption features enough to permit such effects to be observed in airborne thermal infrared imagery collected with the NASA TIMS instrument. Analysis of this Tims imagery suggests that shocked and displaced target rocks can be readily identified. Aircraft multi-frequency imaging radar data collected with the NASA/JPL SAR polarimeter clearly reveals the textural pattern of the preserved components of the ejecta blanket. SPOT multi-spectral imagery of Bosumtwi, Ghana, illustrates the difficulties associated with remote sensing in highly vegetated terrains. Nevertheless, the imagery reveals the subtle expression of an outer tectonic ring at the crater, and may be sensitive to geobotanical variations associated with impact-related suevite deposits. In contrast, the Zhamanshin impact feature on the arid, sedimentary plains of Kazakhstan is ideal for multi-spectral remote sensing, although much of the expected morphologic expression of the complex crater is missing or subdued. Virtually all of the field-mapped impact-related deposits display a unique spectral pattern in decorrelated Landsat Thematic Mapper imagery. The extensive deposits of allogenic breccias, which cap the hills defining the inner ring of the crater, are very distinctive, as are certain of the impact glass deposits. A second, or outer, ring at 13–13.5 km is apparent in the decorrelated principal component TM imagery. The suggestion is that spectral disruption patterns for large, multi-ring impact features in arid settings should be identifiable from orbit. By examining a pristine 144 km diameter multi-ring impact feature on the Venus rolling plains, an impression of the original morphology of a continental impact crater of the magnitude of the Cretaceous-Tertiary (K/T) boundary impact structure can be deduced. The 35 Ma Popigai structure is the only known 100 km class impact crater on Earth approximately equal in age or younger than the K/T event, and its morphology is poorly expressed in single-band Landsat imagery. Thus, spectral anomalies associated with key impact deposits, such as allogenic breccias, suevite, melt, and glasses may have to form the basis for identifying candidate K/T impact sites in the absence of preserved morphologic elements of the crater. It is apparent that remote sensing is not a panacea for the discovery and validation of new impact craters, but it can contribute by serving as a pathfinder both for the identification of promising structures and the possible locations of key deposits for detailed fieldwork and sampling.

Fires in Abandoned Coal Mines

Mine fires occur on abandoned mine lands throughout the U. S. coal fields. They threaten the health and safety of the local populations and consume a non-renewable natural resource. In general, mine fires are the most costly abandoned mine lands problem to mitigate. In active mines, fires are quickly extinguished by the mining company as they present a direct threat to their economic resource. In abandoned mines, however, fires started by natural or other means are often unnoticed for many years, or are ignored or otherwise unattended until they become a threat to nearby residents. These fires then become a government responsibility. Methods of assessing an underground mine fire are often a function of project size and include field reconnaissance, airborne thermal infrared imagery, surface and underground map analysis, drilling, instrumentation and monitoring and underground temperature and mine gas analysis. Effective remedial measures may be a combination of mitigation technologies that depend on whether the goal is to extinguish or limit the spread of an underground mine fire. Such technologies include total excavation or trenching, flooding and quenching, bulk filling mine workings, surface seals, tunnel plugs in mine workings, inert gas injection, chemical foams and burnout control. If fire control or extinguishment methods are not implemented, then the alternative is to abandon the surface and let the fire spread to its natural limits. Case histories of mine fire projects in Pennsylvania9s anthracite and bituminous coal fields demonstrate successful extinguishment by utilizing a combination of mitigation technologies.

Remote sensing data of SP Mountain and SP Lava flow in North-Central Arizona

Multifrequency airborne radar image data of SP Mountain [Official name of feature (U.S. Geological Survey, 1970)] and SP flow (and vicinity) in north-central Arizona were obtained in diverse viewing directions and direct and cross-polarization, then compared with surface and aerial photography, LANDSAT multispectral scanner data, airborne thermal infrared imagery, surface geology, and surface roughness statistics. The extremely blocky, basaltic andesite of SP flow is significantly brighter on direct-polarization K- band (0.9-cm wavelength) images than on cross-polarized images taken simultaneously. Conversely, for the longer wavelength (25 cm) L- band radar images, the cross-polarization image returns from SP flow are brighter than the direct-polarized image. This effect is explained by multiple scattering and the strong wavelength dependence of polarization effects caused by the rectilinear basaltic andesite scatters. Two distinct types of surface relief on SP flow, one extremely blocky, the other subdued, are found to be clearly discriminated on the visible and thermal wavelength images but are separable only on the longer wavelength L- band radar image data. The inability of the K- and X- (3- cm wavelength) band radars to portray the differences in roughness between the two SP flow surface units is attributed to the radar frequency dependence of the surface-relief scale, which, described as the Rayleigh criterion, represents the transition between quasispecular and primarily diffuse backscatter.

A surface thermal anomaly in the region of Chaudes-Aigues (France) detected on aerial thermographs

In the course of an aerial survey mission with an infrared scanning radiometer (10.5–12.5 μm) performed in 1974 over an area of eruptive volcanic rocks, a surface thermal anomaly has been detected in the vicinity of Chaudes-Aigues (France). Its amplitude, +2 to +3 °C, is close to the one produced by hyperthermal springs occuring at Chaudes-Aigues. The existence of this anomaly has been confirmed by in-situ surface temperature measurements performed in 1975. This paper reports on the method by which a surface temperature anomaly was confirmed by ground measurements, using contact thermometers and a hand-held Barnes PRT-6 radiometer. An isopleth map of surface thermal anomalies has been produced which is based on the airborne thermal infrared imagery (aerial thermography).

Censusing White-Tailed Deer by Airborne Thermal Infrared Imagery

Censusing White-Tailed Deer by Airborne Thermal Infrared Imagery