Longwave-infrared (LWIR) spectral imaging offers a means for detecting and sourcing halocarbon emissions with high sensitivity, with the principal halocarbon classes of environmental concern being ...detectable at flux rates of ~0.2–2 kg/h. Broad-area airborne LWIR surveys efficiently locate and speciate halocarbon emissions on local to regional scales and can promote more effective compliance efforts. Similar approaches can also contribute to the effective situational awareness and mitigation of releases resulting from infrastructure damage following catastrophic events of natural origin or occurring as a consequence of human action. Three U.S. urban domains were surveyed: Greater Los Angeles, San Francisco East Bay, and New York City. In each of the California conurbations the most frequently observed halocarbons were HFC-134a, HCFC-22, and HFC-152a while in New York HCFC-22, HFC-32, and HFC-134a were prevalent. The most common radiatively important non-halocarbon agents observed in each locale were carbon dioxide and methane.
•Infrared spectral imaging is a high-sensitivity technique for halocarbon detection.•Airborne surveys identify and locate emission hotspots on local to regional scales.•Infrared spectral imaging can facilitate more effective regulatory compliance.
Remote sensing techniques offer significant potential for generating accurate thick oil slick maps critical for marine oil spill response. However, field validation and methodology assessment ...challenges remain. Here, we report on an approach to leveraging oil emissions from the Coal Oil Point (COP) natural marine hydrocarbon seepage offshore of southern California, where prolific oil seepage produces thick oil slicks stretching many kilometers. Specifically, we demonstrate and validate a remote sensing approach as part of the Seep Assessment Study (SAS). Thick oil is sufficient for effective mitigation strategies and is set at 0.15 mm. The brightness temperature of thick oil, TBO, is warmer than oil-free seawater, TBW, allowing segregation of oil from seawater. High spatial-resolution airborne thermal and visible slick imagery were acquired as part of the SAS; including along-slick “streamer” surveys and cross-slick calibration surveys. Several cross-slick survey-imaged short oil slick segments that were collected by a customized harbor oil skimmer; termed “collects”. The brightness temperature contrast, ΔTB (TBO − TBW), for oil pixels (based on a semi-supervised classification of oil pixels) and oil thickness, h, from collected oil for each collect provided the empirical calibration of ΔTB(h). The TB probability distributions provided TBO and TBW, whereas a spatial model of TBW provided ΔTB for the streamer analysis. Complicating TBW was the fact that streamers were located at current shears where two water masses intersect, leading to a TB discontinuity at the slick. This current shear arose from a persistent eddy down current of the COP that provides critical steering of oil slicks from the Coal Oil Point. The total floating thick oil in a streamer observed on 23 May and a streamer observed on 25 May 2016 was estimated at 311 (2.3 bbl) and 2671 kg (20 bbl) with mean linear floating oil 0.14 and 2.4 kg m−1 with uncertainties by Monte Carlo simulations of 25% and 7%, respectively. Based on typical currents, the average of these two streamers corresponds to 265 g s−1 (~200 bbl day−1) in a range of 60–340 bbl day−1, with significant short-term temporal variability that suggests slug flow for the seep oil emissions. Given that there are typically four or five streamers, these data are consistent with field emissions that are higher than the literature estimates.
Airborne thermal-infrared (TIR) imaging spectrometry techniques have been used to detect and track methane and other gaseous emissions from a variety of discrete sources in diverse environmental ...settings, and to enable estimation of the strength of each plume. The high spatial resolution (1–2m) permits attribution of chemical plumes to their source, while the moderate spectral resolution (44nm across the 7.5–13.5μm TIR band) enables identification and quantification of the gaseous plume constituents, even when one is present in considerably greater concentration than the others. Raw imagery was quantitatively analyzed using matched filtering and adaptive coherence techniques. Experiments under controlled conditions demonstrated successful detection of methane point sources at release rates as low as 2.2kg/h (~1dm3/s at NTP).
•Visualization and quantification of discrete methane plumes are described.•Technique entails application of airborne hyperspectral thermal-infrared imaging.•Methodology enables cal/val for satellite methane products at sub-pixel resolutions.
A multi-year airborne field investigation of remote botanical species identification was conducted involving multiple curated botanical collections. The purpose of the study was to better constrain ...the observational conditions that most favor remote identification by longwave-infrared spectral imaging and assess the degree to which confidence metrics developed for remote chemical composition determination could be adapted to botanical species classification. Identification success was examined as a function of spatial resolution and viewing obliquity. A key aim was to articulate a procedure for validating inferred species identifications and evaluating the retrieval methodology’s performance for alleviating confusion between species exhibiting spectral similarity at the foliar scale. It was found that several confounding factors degrade confidence in the species identifications to levels that render the approach impractical in the general case. A number of taxa, predominantly evergreen, were nevertheless identified that are amenable to the technique and for which utility may be viable.
This paper describes the sensor technology, measurement methodology and data analysis algorithms that are used to characterize gaseous emissions observed with a large-area coverage longwave-infrared ...(LWIR) hyperspectral imaging (HSI) sensor. In so doing the demonstrated capability is expanded well beyond the small number of gas species that have typically been reported and also sets these observations within a definitive, comprehensive framework that documents in detail the procedures used for detection, identification, and quantification of atmospheric trace gases using LWIR HSI systems, along with the methodology for determining their respective detection limits. Examples are provided for a 530km2 region of the Los Angeles Basin collected on July 22, 2014.
•Theory and practice of gas remote sensing with airborne LWIR HSI.•Large area survey (530km2) of Los Angeles Basin searched for gaseous effluents.•186 distinct plume sources (22 chemicals) located within the collected region.
The 1999 Hector Mine earthquake ruptured to the surface in eastern California, with >5 m peak right-lateral slip on the Lavic Lake fault. The cumulative offset and geologic slip rate of this fault ...are not well defined, which inhibits tectonic reconstructions and risk assessment of the Eastern California Shear Zone (ECSZ). With thermal infrared hyperspectral airborne imagery, field data, and auxiliary information from legacy geologic maps, we created lithologic maps of the area using supervised and unsupervised classifications of the remote sensing imagery. We optimized a data processing sequence for supervised classifications, resulting in lithologic maps over a test area with an overall accuracy of 71 ± 1% with respect to ground-truth geologic mapping. Using all of the data and maps, we identified offset bedrock features that yield piercing points along the main Lavic Lake fault and indicate a 1036 +27/−26 m net slip, with 1008 +14/−17 m horizontal and 241 +51/−47 m vertical components. For the contribution from distributed shear, modern off-fault deformation values from another study imply a larger horizontal slip component of 1276 +18/−22 m. Within the constraints, we estimate a geologic slip rate of <4 mm/yr, which does not increase the sum geologic Mojave ECSZ rate to current geodetic values. Our result supports previous suggestions that transient tectonic activity in this area may be responsible for the discrepancy between long-term geologic and present-day geodetic rates.
Airborne longwave-infrared (LWIR) spectral imaging is shown to be effective for the high-confidence detection and identification (ID) of photovoltaic (PV) solar panels in both wilderness and urban ...settings. A series of baseline fiducial measurements were acquired during a controlled experiment conducted against a test array consisting of seven PV solar panels of areas ranging from <0.5 to almost 40 m2 assembled in a desert environment so as to minimize spectral clutter. The detection protocol deriving from this experiment was then successfully validated through an aerial survey of PV solar installations carried out in a spectrally and structurally complex urban environment. LWIR detection of PV solar panels offers a capability complementary with existing visible-shortwave infrared (VSWIR) methodologies.
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•CO2, CH4, H2S, and NH3 emissions derived for working research dairy.•IASI-derived NH3 for the Chino Dairies was 8.9 Gg yr−1 for 2008–1017.•Demonstration of mapping satellite ...potential H2S exposure using in situ emission ratios.•H2S emission factor of 21 kg cow-1 yr−1.
Husbandry trace gases that have climate change implications such as carbon dioxide (CO2), methane (CH4) and ammonia (NH3) can be quantified through remote sensing; however, many husbandry gases with health implications such as hydrogen sulfide (H2S), cannot. This pilot study demonstrates an approach to derive H2S concentrations by coupling in situ and remote sensing data.
Using AMOG (AutoMObile trace Gas) Surveyor, a mobile air quality and meteorology laboratory, we measured in situ concentrations of CH4, CO2, NH3, H2S, and wind at a southern California university research dairy. Emissions were 0.13, 1.93, 0.022 and 0.0064 Gg yr−1; emission factors (EF) were 422, 6333, 74, and 21 kg cow−1 yr−1, respectively, for the 306 head herd. Contributing to these strong EF were spillway emissions from a grate between the main cowshed and the waste lagoon identified in airborne remote sensing data acquired by the hyperspectral thermal infrared imager, Mako.
NH3 emissions from the Chino Dairy Complex, also in southern California, were calculated from Infrared Atmospheric Sounding Interferometer (IASI) satellite data for 2008–2017 using average morning winds, yielding a flushing time of 2.7 h, and 8.9 Gg yr−1. The ratio of EF(H2S) to EF(NH3) for the research dairy from AMOG data were applied to IASI NH3 emissions to derive H2S exposure concentration maps for the Chino area, which ranged to 10–30 ppb H2S for many populated areas.
Combining remote sensing with in situ concentrations of multiple emitted gases can allow derivation of emissions at the sub-facility, facility, and larger scales, providing spatial and temporal coverage that can translate into exposure estimates for use in epidemiology studies and regulation development. Furthermore, with high fidelity information at the sub-facility level we can identify best practices and opportunities to sustainably and holistically reduce husbandry emissions.
Methane (CH4) and ammonia (NH3) directly and indirectly affect the atmospheric radiative balance with the latter leading to aerosol generation. Both have important spectral features in the Thermal ...InfraRed (TIR) that can be studied by remote sensing, with NH3 allowing discrimination of husbandry from other CH4 sources. Airborne hyperspectral imagery was collected for the Chino Dairy Complex in the Los Angeles Basin as well as in situ CH4, carbon dioxide (CO2) and NH3 data. TIR data showed good spatial agreement with in situ measurements and showed significant emissions heterogeneity between dairies. Airborne remote sensing mapped plume transport for ∼20 km downwind, documenting topographic effects on plume advection. Repeated multiple gas in situ measurements showed that emissions were persistent on half-year timescales. Inversion of one dairy plume found annual emissions of 4.1 × 105 kg CH4, 2.2 × 105 kg NH3, and 2.3 × 107 kg CO2, suggesting 2300, 4000, and 2100 head of cattle, respectively, and Chino Dairy Complex emissions of 42 Gg CH4 and 8.4 Gg NH3 implying ∼200k cows, ∼30% more than Peischl et al. (2013) estimated for June 2010. Far-field data showed chemical conversion and/or deposition of Chino NH3 occurs within the confines of the Los Angeles Basin on a four to six h timescale, faster than most published rates, and likely from higher Los Angeles oxidant loads. Satellite observations from 2011 to 2014 confirmed that observed in situ transport patterns were representative and suggests much of the Chino Dairy Complex emissions are driven towards eastern Orange County, with a lesser amount transported to Palm Springs, CA. Given interest in mitigating husbandry health impacts from air pollution emissions, this study highlights how satellite observations can be leveraged to understand exposure and how multiple gas in situ emissions studies can inform on best practices given that emissions reduction of one gas could increase those of others.
On surface: Map of IASI ammonia, NH3, columns for the Eastern Los Angeles Basin for 2014. Floating: Mako NH3 column map. Surface shows pink outline of the Chino Diary Complex, grey outlines 70 ppm-m contour of NH3 column. IASI map slightly transparent to provide better surface rendering. The excellent spatial agreement indicates that conditions for Mako were typical. Display omitted
•Airborne remote sense mapping of a dairy trace gas plume for over 20 km.•In situ identification of far-field (70-km) downwind plume by surface in situ and satellite.•Good herd size agreement for a dairy and the Chino Dairy Complex based on multiple gas emissions estimates.•NH3 lifetime was rapid, ∼6 h, likely due to increased oxidation from the higher oxidant loads in Los Angeles.•IASI satellite NH3 and CH4 confirmed downwind plume and transport patterns identified in airborne imaging spectroscopy and surface in situ data.
Airborne remote sensing mapped dairy NH3 and CH4 plumes with good agreement with satellite and in situ data, the latter of which were used to derive emissions and infer herd size.
Mobile in situ concentration and meteorology data were collected for the Chino Dairy Complex in the Los Angeles Basin by AMOG (AutoMObile trace Gas) Surveyor on 25 June 2015 to characterize husbandry ...emissions in the near and far field in convoy mode with MISTIR (Mobile Infrared Sensor for Tactical Incident Response), a mobile upwards-looking, column remote sensing spectrometer. MISTIR reference flux validated AMOG plume inversions at different information levels including multiple gases, GoogleEarth imagery, and airborne trace gas remote sensing data. Long-term (9-yr.) Infrared Atmospheric Sounding Interferometer satellite data provided spatial and trace gas temporal context.
For the Chino dairies, MISTIR-AMOG ammonia (NH3) agreement was within 5% (15.7 versus 14.9 Gg yr−1, respectively) using all information. Methane (CH4) emissions were 30 Gg yr−1 for a 45,200 herd size, indicating that Chino emission factors are greater than previously reported.
Single dairy inversions were much less successful. AMOG-MISTIR agreement was 57% due to wind heterogeneity from downwind structures in these near-field measurements and emissions unsteadiness. AMOG CH4, NH3, and CO2 emissions were 91, 209, and 8200 Mg yr−1, implying 2480, 1870, and 1720 head using published emission factors. Plumes fingerprinting identified likely sources including manure storage, cowsheds, and a structure with likely natural gas combustion.
NH3 downwind of Chino showed a seasonal variation of a factor of ten, three times larger than literature suggests. Chino husbandry practices and trends in herd size and production were reviewed and unlikely to add seasonality. Higher emission seasonality was proposed as legacy soil emissions, the results of a century of husbandry, supported by airborne remote sensing data showing widespread emissions from neighborhoods that were dairies 15 years prior, and AMOG and MISTIR observations. Seasonal variations provide insights into the implications of global climate change and must be considered when comparing surveys from different seasons.
Eight-plume informed (8I) Gaussian inversion model for I-15 downwind (north to south) transect with respect to arbitrary lateral distance (y) for A) ammonia anomaly (NH3′) and winds (u) versus relative northing (x). Plume peaks labeled. Arrows show transect features modeled that indicated the six-plume uninformed model (not shown). B)In situ NH3 and u data superimposed on Mako column ammonia (XNH3) data for 25 Jul. 2014, 1820-1846 UTC (1020-1046 LT), and the 8I model-projected plumes’ origins in the Google Earth environment. Selected transect plume features labeled. White arrows bracket the transect line onto which transect data are projected. Data key on figure. Shown in the Google Earth environment. Display omitted
•Herd size from three different trace gases converge to ±20% of the average value.•Seasonality is observed in NH3 and CH4 satellite data, affecting annualized rates.•Seasonality must be considered when comparing campaigns in different seasons.•NH3 seasonality was 900%; proposed legacy soil emissions, observed in airborne data.•Midsummer Chino dairy emissions were 15.7 Gg NH3 yr−1 and 30 Gg CH4 yr−1.
Where sufficient information from multiple gases and number of likely sources, high emissions accuracy can be achieved for in situ data plume inversion.
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