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Summary Accurate and representative determination of greenhouse gases (GHG) from oil and gas (O&G) production facilities requires high-spatial-resolution data, which can be acquired by airborne imaging spectrometers. However, assessment of nonmethane hydrocarbon emissions, which are far less amenable to remote sensing, requires mobile surface in-situ measurements (e.g., a mobile air quality laboratory). Field in-situ measurements and airborne thermal infrared spectral imagery were acquired for three producing California oil fields (Poso Creek, Kern Front, and Kern River) located next to each other on 14 September 2018. In addition, a profile ascending a nearby mountain collected in-situ data for the Round Mountain oilfield. Plume methane to ethane ratios were consistent within different regions of the field and differed between these fields in a manner related to field geological structures. Data acquired by an airborne thermal infrared imaging spectrometer, Mako, in 2015 and 2018 showed most emissions were from distant plumes in the Kern Front and Poso Creek fields. The spatial distribution of detected plumes was strongly related to faults, particularly active faults, which are proposed to stress infrastructure, leading to higher fugitive emissions and/or emissions from natural migration pathways (seepage). Additionally, the spatial distribution of detected plumes suggested unmapped faults. Thus, high-sensitivity imaging spectroscopy can improve understanding of reservoir geological structures that impact hydrocarbon migration and field operations, highlighting the potential for a novel reservoir management tool.

Air pollution, particularly fine and ultrafine particulate matter aerosols, underlies a wide range of communicable and non-communicable disease affecting many systems including the cardiopulmonary and immune systems, and arises primarily from transportation and industry. A number of air pollution driven diseases also are Covid19 comorbidities. Thus, a number of studies on air pollution exposure, particularly particulate matter, strongly indicate air pollution is an important underlying factor in Covid19 transmission, severity, and mortality. This suggests that air pollution from natural sources, particularly wildfires, could play a role in the Covid19 pandemic. We tested this hypothesis on three wildfire smoke events in Orange County, CA, each of which was followed by Covid19 case increases after an approximately one-week lag. This lag was consistent with combined incubation time and testing/reporting times. Moreover, the three events suggest a dose dependency. The wildfire comorbidity hypothesis implies that at-risk-populations should reduce smoke exposure from wildfires, as well as indoors from biomass burning for heating, cooking, and aesthetic purposes.

Despite their importance to climate change, significant current and future source uncertainties remain for the most important carbon greenhouse gases (GHGs) methane (CH4) and carbon dioxide (CO2), particularly for the developing world. Mitigation by effective regulation and treaties requires accurate global GHG budgets, which only global‐scale (satellite) remote sensing can deliver. A high spatial and spectral resolution spectrometer is needed; herein, we present the design concept for a Multi‐Order Carbon Spectral Imager (MOCSI). MOCSI is designed for the global measurement of differential GHG column density and source fingerprinting from low Earth orbit. MOCSI includes three wavebands for CH4, CO2, and carbon monoxide (CO), whose altitude weighting functions emphasize the boundary layer, where the dominant GHG anthropogenic and natural sources are still unmixed and therefore most easily discerned against background levels. CO aids discrimination of megacity and fire GHG emissions from other sources and is also a precursor for ozone, which is also an important GHG. High spectral resolution ensures discrimination of target species from interferents, while high spatial resolution enhances sensitivity for discrete source identification and emission quantification. MOCSI is a compact, high‐throughput shortwave‐infrared pushbroom spectrometer that disperses multiple orders of a single grating onto a single focal plane array to minimize size, weight, and power of the instrument. MOCSI is specified to provide spatial and temporal resolution and sensitivity sufficient to address important global science questions related to megacity emissions, shifts in hydrocarbon production, and disaster response, as well as many others.

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.

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.

The 1999 Hector Mine earthquake ruptured to the surface in eastern California, with &gt, 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 &plusmn, 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/&minus, 26 m net slip, with 1008 +14/&minus, 17 m horizontal and 241 +51/&minus, 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/&minus, 22 m. Within the constraints, we estimate a geologic slip rate of &lt, 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.

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., info:eu-repo/semantics/published

Validation of emissivity (&epsilon, ) retrievals from spaceborne thermal infrared (TIR) sensors typically requires spatial extrapolations over several orders of magnitude for a comparison between centimeter-scale laboratory &epsilon, measurements and the common decameter and lower resolution of spaceborne TIR data. In the case of NASA&rsquo, s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) temperature and &epsilon, separation algorithm (TES), this extrapolation becomes especially challenging because TES was originally designed for the geologic surface of Earth, which is typically heterogeneous even at centimeter and decameter scales. Here, we used the airborne TIR hyperspectral Mako sensor with its 2.2 m/pixel resolution, to bridge this scaling issue and robustly link between ASTER TES 90 m/pixel emissivity retrievals and laboratory &epsilon, measurements from the Algodones dune field in southern California, USA. The experimental setup included: (i) Laboratory XRD, grain size, and TIR spectral measurements, (ii) radiosonde launches at the time of the two Mako overpasses for atmospheric corrections, (iii) ground-based thermal measurements for calibration, and (iv) analyses of ASTER day and night &epsilon, retrievals from 21 different acquisitions. We show that while cavity radiation leads to a 2% to 4% decrease in the effective emissivity contrast of fully resolved scene elements (e.g., slipface slopes and interdune flats), spectral variability of the site when imaged at 90 m/pixel is below 1%, because at this scale the dune field becomes an effectively homogeneous mixture of the different dune elements. We also found that adsorption of atmospheric moisture to grain surfaces during the predawn hours increased the effective &epsilon, of the dune surface by up to 0.04. The accuracy of ASTER&rsquo, s daytime emissivity retrievals using each of the three available atmospheric correction protocols was better than 0.01 and within the target performance of ASTER&rsquo, s standard emissivity product. Nighttime emissivity retrievals had lower precision (&lt, 0.03) likely due to residual atmospheric effects. The water vapor scaling (WVS) atmospheric correction protocol was required to obtain accurate (&lt, 0.01) nighttime ASTER emissivity retrievals.

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 530 km 2 region of the Los Angeles Basin collected on July 22, 2014.

The Salton Trough lies in the transition between the San Andreas Fault and oblique spreading centers and transform faults in the Gulf of California. The Salton Sea Geothermal Field is the northernmost expression of those spreading centers. In ~ 2007 two ammonia-emitting fumarole fields that had been submerged beneath the Salton Sea were exposed for the first time in nearly 50 years. As the sea level continued to drop these fields have developed a number of boiling pools, mud pots, gryphons and a unique suite of ammonium sulfate minerals. These have been studied over time with long-wave infrared remote sensing coupled with ground truth surveys backed by laboratory analyses of the minerals. Many vents lie at the center of concentric rings of mineralization with systematic occurrence of different minerals from center to edge. Three semi-concentric zones (fumarole, transition and evaporite) have been defined with respect to ammonia-emitting vents and bubbling pools. The scale of these zones range from several meters, localized around individual vents, to that of the fumarole fields as a whole. The fumarole zone is closest to the vents and locally contains cavernous sulfur crystals and significant deposits of gypsum, mascagnite, boussingaultite and other ammonium sulfates. The transition zone comprises a dark brown surficial band of inconspicuous sodium nitrate underlain by anhydrite/bassanite that is thought to have formed by ammonia-oxidizing microbes interacting with the ammonium sulfates of the outer fumarole zone. The evaporite zone is the outermost and contains blodite, thenardite and glauberite, which are typical of the sulfates associated with the shoreline of the Salton Sea. Remote sensing has shown that the mineral zones have remained relatively stable from 2013 to 2017, with minor variations depending on rainfall, temperature and levels of agricultural runoff.

An airborne hyperspectral imager operating in the midwave-infrared spectral range is described. The Mid-infrared Airborne Hyperspectral Imager (MAHI) features 3.3-nm spectral sampling over its 3.3– $5.4~\mu \text{m}$ wavelength range. MAHI operates in a roll-stabilized pushbroom configuration with 480 cross-track pixels, each with an instantaneous field-of-view (IFOV) of 0.94 mrad, to provide for a total FOV of 25.8°. The sensor spectroradiometric performance is illustrated by case studies featuring the detection, identification, and quantification of a number of fugitive gaseous emissions from industrial sources.

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.

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. Where sufficient information from multiple gases and number of likely sources, high emissions accuracy can be achieved for in situ data plume inversion., SCOPUS: ar.j, info:eu-repo/semantics/published

The Mako airborne longwave-infrared hyperspectral sensor is a whiskbroom imager operating in the 7.6-13.2 μm region with 44-nm spectral sampling and

A new airborne facility instrument for Earth science applications is introduced. The Mineral and Gas Identifier (MAGI) is a wide-swath (programmable up to ±42° off nadir) moderate spectral resolution thermal-infrared (TIR) imaging spectrometer that spans the 7.1- to 12.7- $\mu\mbox{m} $ spectral window in 32 uniform and contiguous channels. Its spectral resolution enables improved discrimination of rock and mineral types, greatly expanded gas-detection capability, and generally more accurate land-surface temperature retrievals. The instrument design arose from trade studies between spectral resolution, spectral range, and instrument sensitivity and has now been validated by flight data acquired with the completed sensor. It offers a potential prototype for future space-based TIR instruments, which will require much higher spectral resolution than is currently available in order to address more detailed climate, anthropogenic, and solid Earth science questions.

The prediction of tropical cyclone rapid intensification is one of the most pressing unsolved problems in hurricane forecasting. The signatures of gravity waves launched by strong convective updrafts are often clearly seen in airglow and carbon dioxide thermal emission spectra under favorable atmospheric conditions. By continuously monitoring the Atlantic hurricane belt from the main development region to the vulnerable sections of the continental United States at high cadence, it will be possible to investigate the utility of storm-induced gravity wave observations for the diagnosis of impending storm intensification. Such a capability would also enable significant improvements in our ability to characterize the 3D transient behavior of upper-atmospheric gravity waves and point the way to future observing strategies that could mitigate the risk to human life caused by severe storms. This paper describes a new mission concept involving a midinfrared imager hosted aboard a geostationary satellite positioned at approximately 80°W longitude. The sensor’s 3-km pixel size ensures that the gravity wave horizontal structure is adequately resolved, while a 30-s refresh rate enables improved definition of the dynamic intensification process. In this way the transient development of gravity wave perturbations caused by both convective and cyclonic storms may be discerned in near–real time.

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 (1–2 m) permits attribution of chemical plumes to their source, while the moderate spectral resolution (44 nm across the 7.5–13.5 μm 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 2.2 kg/h (~ 1 dm3/s at NTP).

The Aerospace Corporation’s sensitive Mako thermal infrared imaging spectrometer, which operates between 7.6 and 13.2 microns at a spectral sampling of 44 nm, and flies in a DeHavilland DHC-6 Twin Otter, has undergone significant changes over the past year that have greatly increased its performance. A comprehensive overhaul of its electronics has enabled frame rates up to 3255 Hz and noise reductions bringing it close to background-limited. A replacement diffraction grating whose peak efficiency was tuned to shorter wavelength, coupled with new AR coatings on certain key optics, has improved the performance at the short wavelength end by a factor of 3, resulting in better sensitivity for methane detection, for example. The faster frame rate has expanded the variety of different scan schemes that are possible, including multi-look scans in which even sizeable target areas can be scanned multiple times during a single overpass. Off-nadir scanning to ±56.4° degrees has also been demonstrated, providing an area scan rate of 33 km2/minute for a 2-meter ground sampling distance (GSD) at nadir. The sensor achieves a Noise Equivalent Spectral Radiance (NESR) of better than 0.6 microflicks (μf, 10-6 W/sr/cm2/μm) in each of the 128 spectral channels for a typical airborne dataset in which 4 frames are co-added. An additional improvement is the integration of a new commercial 3D stabilization mount which is significantly better at compensating for aircraft motions and thereby maintains scan performance under quite turbulent flying conditions. The new sensor performance and capabilities are illustrated.

The 1999 Hector Mine earthquake on the Lavic Lake fault produced a maximum right-lateral displacement of ∼5 m, but the long-term cumulative offset remains unresolved. To identify bedrock that has been offset by the fault, we produced a swath map from airborne hyperspectral imagery. High spatial and spectral resolution, along with a lack of significant vegetation cover helped us differentiate lithologic units and create a geologic map with supervised and unsupervised classifications. Supervised classifications over a small test site had an overall accuracy of 71 ± 1%, and some of the boundaries between units in our unsupervised classification correlate well with lithologic boundaries from a previously published geologic map that covers the same area. Our geologic fault swath map will help to resolve the total tectonic offset of bedrock along the Lavic Lake fault.

Several ammonia emitting fumarole fields have recently been exposed along the southeastern shoreline of the Salton Sea in Imperial County, California. A complex assemblage of sulfate minerals, many containing ammonium ion, are associated with the fumaroles. The distribution of these sulfates was mapped by remote sensing with the Mako LWIR hyperspectral sensor. The most common minerals tended to form somewhat concentric discontinuous rings. Outwardly from the central fumarole vent, they were: mascagnite/boussingaultite, gypsum, nitratine and bloedite, respectively. Ground truth surveys coupled with laboratory analyses were generally in good agreement with the remote sensing results.

The advantages of airborne hyperspectral longwave-infrared imaging for emissions monitoring are described in the context of urban-industrial environments. These benefits are illustrated by means of several case studies.

Methane, CH4, and ammonia, NH3, directly and indirectly influence the atmospheric radiative balance. Long wave infrared (LWIR) airborne hyperspectral imagery and in situ data of CH 4 , CO 2 , and NH 3 plumes were collected from the Chino Dairy Complex in the Los Angeles Basin. LWIR data showed significant emissions heterogeneity between dairies with good spatial agreement with in situ measurements. Remote sensing data also showed topographic effects on plumes mapped for at least 19 km. Repeated 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 CH 4 , 2.2×105kg NH 3 , and 2.3×107 kg CO 2 , suggesting 3500, 4000, and 2100 head of cattle, respectively. Far field data showed chemical conversion of Chino NH 3 occurs within the confines of the Los Angeles Basin on % day timescale, faster than previously published values.

A multi-year study of ammonia emissions from a recently exposed geothermal fumarole field at the SE edge of the Salton Sea (Southern California) is described. The work makes extensive use of airborne thermal-infrared hyperspectral imagery acquired over the field site.

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.

We describe the 2016 update of the NASA Earth Science Technology Office (ESTO) investment strategy in the area of lidar technologies as pertaining to NASA's Earth Science measurement goals in the next decade.

The typically weak cross-sections characteristic of Raman processes has historically limited their use in atmospheric remote sensing to nighttime application. However, with advances in instrumentation and techniques, it is now possible to apply Raman lidar to the monitoring of atmospheric water vapor, aerosols and clouds throughout the diurnal cycle. Upper tropospheric and lower stratospheric measurements of water vapor using Raman lidar are also possible but are limited to nighttime and require long integration times. However, boundary layer studies of water vapor variability can now be performed with high temporal and spatial resolution. This paper will review the current state-of-the-art of Raman lidar for high-resolution measurements of the atmospheric water vapor, aerosol and cloud fields. In particular, we describe the use of Raman lidar for mapping the vertical distribution and variability of atmospheric water vapor, aerosols and clouds throughout the evolution of dynamic meteorological events. The ability of Raman lidar to detect and characterize water in the region of the tropopause and the importance of high-altitude water vapor for climate-related studies and meteorological satellite performance are discussed.

In late April 1998 an extreme Asian dust episode reached the U.S. western seaboard. This event was observed by several in situ and remote sensing atmospheric measurement stations. Dramatic reductions in boundary layer visibility were recorded and the resultant peak backscatter coefficients exceeded prevailing upper tropospheric background conditions by at least 2 orders of magnitude. An analysis of this event is given using lidar vertical backscatter profilometry, concurrent Sun photometer opacity data, and transport modeling. At San Nicolas Island the measured and modeled aerosol optical thickness at 500 nm increased dramatically from 0.15 on April 25 to 0.52 on April 26-27. Volume size distribution on April 27 exhibited a prominent coarse mode at 1-2 μm radius, and single-scattering albedo was observed to increase from 0.90 in the blue to 0.93 in the near infrared. Concurrent lidar observations tracked the evolution of the plume vertical structure, which consisted of up to three well-defined layers distributed throughout the free troposphere.

In 1992 the atmospheric lidar remote sensing groups of the National Aeronautics and Space Administration Marshall Space Flight Center, the National Oceanic and Atmospheric Administration/Environmental Technology Laboratory (NOAA/ETL), and the Jet Propulsion Laboratory began a joint collaboration to develop an airborne high-energy Doppler laser radar (lidar) system for atmospheric research and satellite validation and simulation studies. The result is the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS), which has the capability to remotely sense the distribution of wind and absolute aerosol backscatter in three-dimensional volumes in the troposphere and lower stratosphere. A factor critical to the programmatic feasibility and technical success of this collaboration has been the utilization of existing components and expertise that were developed for previous atmospheric research by the respective institutions. For example, the laser transmitter is that of the mobile ground-based Do...

Tropospheric and lower stratospheric aerosol backscatter profiles were obtained with an airborne backscatter lidar at 9.25-μm wavelength during the NASA Global Backscatter Experiment (GLOBE) airborne field campaigns in November 1989 and May/June 1990. The range of latitudes extended from 70°N to 62°S over the Pacific Ocean basin. The data provide evidence that the tropics are an effective sink for aerosol particles in the lidar-active size range, most likely through efficient wet deposition processes. A reduction of planetary boundary layer (PBL) thickness and aerosol mass density was observed within the tropical regions of enhanced cumulus convection. PBL thickness maxima were consistently observed in the southern hemisphere at subtropical and high latitudes. The downward transport of volcanic aerosol from the February 1990 Kelut eruption into the upper troposphere was observed in the southern hemisphere during the May/June 1990 period. A springtime enhancement of aerosol in the middle troposphere, due to convection and transport of surface material, was observed in both hemispheres, although the seasonal enhancement was much more dramatic in the northern hemisphere due to the influence of the Asian continental source. Above the PBL the observed springtime enhancement was in the form of extensive layers, with the high-altitude layers reaching the midlatitude tropopause near 140°E longitude.

The evolution of the volcanic debris plume originating from the June 1991 eruption of Mt. Pinatubo has been monitored since its genesis using a ground-based backscatter lidar facility sited at the Jet Propulsion Laboratory (JPL). Both absolute and relative pre- and post-Pinatubo backscatter observations are in accord with Mie scattering projections based on measured aerosol particle size distributions reported in the literature. The post-Pinatubo column-integrated backscatter coefficient peaked approximately 400 days after the eruption, and the observed upper boundary of the aerosol column subsided at a rate of approximately 200 m/mon.

The use of an airborne CO2 lidar to obtain cloud backscatter and extinction data at a thermal infrared wavelength is described. The extinction in this spectral region is proportional to the cloud liquid water content. The use of coherent detection results in high sensitivity and narrow field of view, the latter property greatly reducing multiple-scattering effects. Backscatter measurements in absolute units are obtained through a hard target calibration methodology. For clouds of low to moderate optical thickness at the lidar wavelength, both geometric thickness and optical thickness can be measured. The sea surface reflectance signal is used to obtain estimates of the cloud optical thickness. The utility of this technique results from studies that indicate that the spatial scale of variability of the sea surface reflectance is generally large compared with that of cloud optical thickness. Selected results are presented from data taken during flights over the Pacific Ocean.

[1] Airborne hyperspectral imaging surveys were conducted over a geothermally active region straddling the southeastern shore of the Salton Sea in Southern California. The imagery was acquired across the 7.6–13.5 μm longwave-infrared region with a ground sample distance of approximately 1 m. Prominent thermal hot spots associated with fumaroles along a known fault line were observed to coincide with emission of free ammonia, presumed to originate from geothermally induced pyrolytic decomposition of nitrogenous compounds that permeate the lake water, sediment, and adjacent agricultural terrain. It is shown that the inferred fluxes of ammonia constitute a significant fraction (10–25%) of the total atmospheric ammonia burden assessed for the Salton Sea environs and represent a previously unreported source for that locale.

A new airborne thermal infrared imaging spectrometer, "Mako", with 128 bands in the thermal infrared covering 7.8 to 13.4 microns, has recently completed its engineering flight trials. Results from these flights, which occurred in September 2010 and included two science flights, are presented. The new sensor flies in a Twin Otter aircraft and operates in a whiskbroom mode, giving it the ability to scan to ±40° around nadir. The sensor package is supported on a commercial 3-axis-stabilized mount which greatly reduces aircraft-induced pointing jitter. The internal optics and focal plane array are operated near liquid helium temperatures, which in conjunction with a fast f/1.25 spectrometer enables low noise performance despite the sensor's small (0.55 mrad) pixel size and the high frame rate needed to cover large whisk angles. Besides the large-area-coverage scan mode (20 km2 per minute at 2-meter GSD from 12,500 ft. AGL), the sensor features a scan mirror pitch capability that enables both a high-sensitivity mode (longer integration times using frame summing, covering a smaller spatial region) and a multiple-look mode (multiple looks at a smaller region in a single aircraft overpass, for discriminating plume motion, for example).

An airborne CO(2) coherent lidar has been developed and flown on over 30 flights of the NASA DC-8 research aircraft to obtain aerosol and cloud backscatter and extinction data at a wavelength near 9µm. Designed to operate in either zenith- or nadir-directed modes, the lidar can be used to measure vertical profiles of backscatter throughout the vertical extent of the troposphere and the lower stratosphere. Backscatter measurements in absolute units are obtained through a hard-target calibration methodology. The use of coherent detection results in high sensitivity and narrow field of view, the latter property greatly reducing multiple-scattering effects. Aerosol backscatter profile intercomparisons with other airborne and ground-based CO(2) lidars were conducted during instrument checkout flights over the NASA Ames Research Center before extended depolyment over the Pacific Ocean. Selected results from data taken during the flights over the Pacific Ocean are presented, emphasizing intercom arisons with backscatter profile data obtained at 1.06 µm with a NASA Goddard Space Flight Center Nd:YAG lidar on the same flights.

An update is provided on the Jet Propulsion Laboratory aerosol backscatter climatology database, with emphasis on the impact of the June 1991 eruption of Mt. Pinatubo. The data set is acquired at thermal infrared wavelengths with a range-gated coherent CO(2) lidar system, which has been in regular operation since 1984. A number of analyses have been carried out to assess long-term trends in the tropospheric and lower stratospheric aerosol backscatter, as observed from the lidar site at Pasadena, California.

We demonstrate how the design of graded-reflectance output coupler unstable laser cavities may be tailored to significantly enhance the overall power transmission efficiency of a given laser system relative to that of a conventional diffractively coupled unstable resonator. The importance of these findings in coherent lidar applications is explained with particular emphasis on projected space-based systems.

The paper reports a series of atmospheric aerosol backscatter measurements at two widely spaced CO2 laser wavelengths: 9.25 and 10.6 microns. Comparisons are made between backscatter coefficient profiles at these two wavelengths up to 20-km altitude. Measurements such as those reported here can be used to assess the feasibility of coherent CO2 lidar for wind measurements, and they also provide a partial test of backscatter model predictions.

A novel thermal-band imager is proposed for space-based Earth science measurement applications such as rock identification and volcano monitoring. The instrument, MAGI-L (Mineral and Gas Identifier - LEO), would also enable detection of gases from natural and anthropogenic sources. Its higher spectral resolution, compared to ASTER-type sensors, will improve discrimination of rock types, greatly expand the gas-detection capability, and result in more accurate land-surface temperatures. The optical design for MAGI-L will incorporate a novel compact Dyson spectrometer. Data from SEBASS have been used to examine the trade-offs between spectral resolution, spectral range, and instrument sensitivity for the proposed sensor.

The diode-laser array working group (DAWG) is a national-level consumer/provider forum for discussion of engineering and manufacturing issues which influence the reliability and survivability of high-power broad-area laser diode devices in space, with an emphasis on laser diode arrays (LDAs) for optical pumping of solid-state laser media. The goals of the group are to formulate and validate standardized test and qualification protocols, operational control recommendations, and consensus manufacturing and certification standards. Reliability and lifetime data collected by laser diode manufacturers and the user community are being used to develop standardized guidelines for specifying and qualifying laser diodes for long-duration operation in space. Effective implementation of statistical design techniques at the supplier design, development, and manufacturing levels will aid in reducing product performance variability and improve product reliability for diodes employed in space applications. The ultimate goal is to promote an informed U.S. Government investment and procurement strategy for assuring the availability and durability of space-qualified LDAs.

The dependence of sea surface directional reflectance on surface wind stress suggests a method for deriving surface wind speed from space-based lidar measurements of sea surface backscatter. In particular, lidar measurements in the nadir angle range from 10 degrees to 30 degrees appear to be most sensitive to surface wind-speed variability in the regime below 10 m/s. The Lidar In-space Technology Experiment (LITE) shuttle lidar mission of September 1994 provided a unique opportunity to measure directional backscatter at selected locations by use of the landmark track maneuver and to measure fixed-angle backscatter from the ocean surfaces on a global scale. During the landmark track maneuver the shuttle orbiter orientation and roll axis are adjusted continuously to maintain the lidar footprint at a fixed location for a duration of ~1 min. Several data sets were converted to calibrated reflectance units and compared with a surface reflectance model to deduce surface wind speeds. Comparisons were made with ERS-1 scatterometer data and surface measurements.

In late 2005 the NASA Earth Science Technology Office convened a working group to review decadal-term technology needs for Earth science active optical remote sensing objectives. The outcome from this effort is intended to guide future NASA investments in laser remote sensing technologies. This paper summarizes the working group findings and places them in context with the conclusions of the National Research Council assessment of Earth science needs, completed in 2007.

Progress in laser sources for surface and atmospheric remote sensing is placed in the context of 3D mapping and imaging laser radar systems and ambitions for future high resolution mapping systems.

Although laser remote sensing techniques have been applied to a variety of environmental measurement tasks for several decades, it has not been until relatively recently that the promise held by lidar and laser radar has begun to be exploited for global measurements from an Earth-orbiting vantage point. Notwithstanding the successful demonstration of highresolution laser altimetry and cloud/aerosol profiling from orbital platforms in the last decade, full realization of the potential for these techniques to address important Earth science questions awaits the availability of next generation instruments incorporating durable, high-performance laser transmitters and advanced receiver technologies. Some of the most critical, high-impact Earth science measurement applications are enabled by lidar techniques - in some cases uniquely so. This paper describes some of these scenarios and also the philosophy underlying the investment that the US National Aeronautics and Space Administration (NASA) is making in order to pro-actively accelerate technology development in certain key areas that will contribute to our future ability to field advanced laser remote sensing instrumentation in space.

[1] Dust devils are significant meteorological phenomena on Mars: They are ubiquitous, continually gardening the Martian surface, and may be the primary atmospheric dustloading mechanism in nonstorm seasons. Further, dust grains in the swirling dust devils may become electrically charged via triboelectric effects. Electrical effects associated with terrestrial dust devils have been reported previously, but these were isolated measurements (electric fields only) with no corroborating measurements. To study the fluid and electrical forces associated with dust devils, NASA’s Human Exploration and Development of Space (HEDS) enterprise sponsored a set of desert field tests with a suite of mutually compatible and complementary instruments in order to determine the relationship between electric, magnetic, and fluid forces. The project (originally a selected flight project) was entitled ‘‘Martian ATmosphere And Dust in the Optical and Radio’’ (MATADOR). In this work, we present a number of interesting examples of the electromagnetic nature of the dust devil. We also describe potential hazards of the dust devil and how similar devil- and storm-related forces on Mars might affect any human occupation. INDEX TERMS: 6225 Planetology: Solar System Objects: Mars; 3304 Meteorology and Atmospheric Dynamics: Atmospheric electricity; 3379 Meteorology and Atmospheric Dynamics: Turbulence; 3394 Meteorology and Atmospheric Dynamics: Instruments and techniques; 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); KEYWORDS: triboelectricity, electric fields, dust devils, magnetic fields, atmospheric electricity

An intensive 3-day dust devil investigation was conducted near Eloy, Arizona, during June of 2001. The goal was to evaluate strategies for observing dust devils on Mars by studying the physics of terrestrial dust devils.

A high average power and high spectral brightness free-electron laser (FEL) being developed at the University of Hawaii as a lidar transmitter for atmospheric and oceanic research. The FEL will be tunable from the UV to the mid-infrared. Peak power in the picosecond long micropulses of the FEL will reach 10 s of MW, and these will average to the order of 100 kW over the 5 microsecond long macropulses. The repetition rate of the micropulses will be in the range 1 to 3 GHz during one macropulse, and the macropulses will repeat at 180 Hz. The unique pulse structure of the FEL output with high pulse power will allow exploitation of non-linear optical spectroscopic techniques for identifying various types of aerosols and pollutants in the atmosphere. The wide tunable range in the mid-IR region will allow sensitive detection of chemical species by operating the FEL transmitter in the differential absorption lidar (DIAL) mode, and the high spectral brightness will allow unprecedented signal-to-noise ratio.

Although nearly all the airborne and orbiting active laser sensors to date have operated at near nadir pointing angles, in either lidar or altimeter mode, the authors anticipate dual-mode instruments such as GLAS to emerge and impact the remote sensing community in the next decade. They discuss the variability which off-nadir scanning brings to the measurement concepts-variability which can engender new measurement capabilities as well as cause interpretational problems. In that context they discuss the dynamic range of surface reflectance (backscatter) over water and various land surfaces, including dependence on nadir angle. A new measurement opportunity which exists using scanning lidar systems optimized for wide dynamic range is the measurement of surface wind over oceans.

[1] Scattering properties of tropospheric aerosol layers were observed with airborne lidars during the Global Backscatter Experiment (GLOBE) airborne campaigns covering a wide range of latitude and longitude over the Pacific Ocean. Lidar data at 0.532, 1.064, 1.54, and 9.25 μm wavelengths are used to study the vertical profiles and optical properties of the marine boundary layer (MBL) as well as elevated dust layers due to transport of material from Asia. The lidars were calibrated to provide absolute aerosol backscatter coefficients at their respective wavelengths. The lidar data are compared with predictions based on commonly used dust and sea salt aerosol refractive index and size distribution parameters. Published observations of aerosol characteristics from onboard in situ sensors are used to verify locations where mineral dust aerosol dominated the aerosol optical properties in the free troposphere. Relative humidity has a major impact on the observed MBL aerosol scattering characteristics. The multiwavelength observations of the dust layers are consistent with the assumption that for the particle size range that dominates the scattering properties the particle size distribution varies little over 103 km transport distances and is not strongly dependent on altitude. A nonsphericity effect on the dust scattering, in particular the suppression of backscattering at the shorter lidar wavelengths, is discussed in the context of data comparisons with model predictions. The observations of the sea salt aerosol scattering in the remote MBL indicate that at altitudes above 150 m in optically clear conditions the influence of the supermicron coarse mode is minor compared with that of the submicron accumulation mode.