ALBERT

Description: Fugitive emissions from waste disposal sites are important anthropogenic sources of the greenhouse gas methane (CH4). As a result of the growing world population and the recognition of the need to control greenhouse gas emissions, this anthropogenic source of CH4 has received much recent attention. However, the accurate assessment of the CH4 emissions from landfills by modeling and existing measurement techniques is challenging. This is because of inaccurate knowledge of the model parameters and the extent of and limited accessibility to landfill sites. This results in a large uncertainty in our knowledge of the emissions of CH4 from landfills and waste management. In this study, we present results derived from data collected during the research campaign COMEX (CO2 and MEthane eXperiment) in late summer 2014 in the Los Angeles (LA) Basin. One objective of COMEX, which comprised aircraft observations of methane by the remote sensing Methane Airborne MAPper (MAMAP) instrument and a Picarro greenhouse gas in situ analyzer, was the quantitative investigation of CH4 emissions. Enhanced CH4 concentrations or CH4 plumes were detected downwind of landfills by remote sensing aircraft surveys. Subsequent to each remote sensing survey, the detected plume was sampled within the atmospheric boundary layer by in situ measurements of atmospheric parameters such as wind information and dry gas mixing ratios of CH4 and carbon dioxide (CO2) from the same aircraft. This was undertaken to facilitate the independent estimation of the surface fluxes for the validation of the remote sensing estimates. During the COMEX campaign, four landfills in the LA Basin were surveyed. One landfill repeatedly showed a clear emission plume. This landfill, the Olinda Alpha Landfill, was investigated on 4 days during the last week of August and first days of September 2014. Emissions were estimated for all days using a mass balance approach. The derived emissions vary between 11.6 and 17.8 kt CH4 yr−1 with related uncertainties in the range of 14 to 45 %. The comparison of the remote sensing and in situ based CH4 emission rate estimates reveals good agreement within the error bars with an average of the absolute differences of around 2.4 kt CH4 yr−1 (±2. 8 kt CH4 yr−1). The US Environmental Protection Agency (EPA) reported inventory value is 11.5 kt CH4 yr−1 for 2014, on average 2.8 kt CH4 yr−1 (±1. 6 kt CH4 yr−1) lower than our estimates acquired in the afternoon in late summer 2014. This difference may in part be explained by a possible leak located on the southwestern slope of the landfill, which we identified in the observations of the Airborne Visible/Infrared Imaging Spectrometer – Next Generation (AVIRIS-NG) instrument, flown contemporaneously aboard a second aircraft on 1 day.

Description: Visible–shortwave infrared imaging spectroscopy provides valuable remote measurements of Earth's surface and atmospheric properties. These measurements generally rely on inversions of computationally intensive radiative transfer models (RTMs). RTMs' computational expense makes them difficult to use with high-volume imaging spectrometers, and forces approximations such as lookup table interpolation and surface–atmosphere decoupling. These compromises limit the accuracy and flexibility of the remote retrieval; dramatic speed improvements in radiative transfer models could significantly improve the utility and interpretability of remote spectroscopy for Earth science. This study demonstrates that nonparametric function approximation with neural networks can replicate radiative transfer calculations and generate accurate radiance spectra at multiple wavelengths over a diverse range of surface and atmosphere state parameters. We also demonstrate such models can act as surrogate forward models for atmospheric correction procedures. Incorporating physical knowledge into the network structure provides improved interpretability and model efficiency. We evaluate the approach in atmospheric correction of data from the PRISM airborne imaging spectrometer, and demonstrate accurate emulation of radiative transfer calculations, which run several orders of magnitude faster than first-principles models. These results are particularly amenable to iterative spectrum fitting approaches, providing analytical benefits including statistically rigorous treatment of uncertainty and the potential to recover information on spectrally broad signals.

Description: An integrated workflow to estimate the hydrocarbon-in-place and recovery factor is applied in the Bakken-Three Forks petroleum system. Evaluating factors that control the generation and storage of hydrocarbon, such as the total organic carbon, maturity of shale, thickness, porosity, and permeability is a challenge in any shale play study. In addition, the hybrid nature of the Bakken petroleum system, where the source and reservoir rock are present within a short depth interval, adds complexity to the production interpretation and outlook of the play. One complexity is the contribution from Upper and Lower Bakken organic-rich shales to the production of horizontal wells completed in the Middle Bakken low-permeability laminated sandstone/siltstone and Upper Three Forks sandy/silty dolostone. We have performed geologic and petrophysical studies and calculate and map the hydrocarbon pore volume. For fluid characterization, we use three models to accurately cover a range of American Petroleum Institute gravity and gas/oil ratio. We evaluate the contribution of Upper and Lower Bakken to production by constructing simulation models and used that knowledge to estimate the recovery factor of the horizontal wells. Production depletes the Middle Bakken, creating a pressure difference between the Middle Bakken and the Upper/Lower Bakken, which in turn depletes the Upper/Lower Bakken. Vertical permeability controls production from the Upper and Lower Bakken, and higher vertical permeability increases the contribution of the two shale members. An understanding of the maturity and trap mechanism can help to explain the water-saturation distribution, and understanding these factors is crucial to any future development of the play.

Description: An Arctic and Antarctic sea ice area and extent dataset has been generated by EUMETSAT's Ocean and Sea Ice Satellite Application Facility (OSISAF) using the record of microwave radiometer data from NASA's Nimbus 7 Scanning Multichannel Microwave radiometer (SMMR) and the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) and Special Sensor Microwave Imager and Sounder (SSMIS) satellite sensors. The dataset covers the period from October 1978 to April 2015 and updates and further developments are planned for the next phase of the project. The methodology for computing the sea ice concentration uses (1) numerical weather prediction (NWP) data input to a radiative transfer model for reduction of the impact of weather conditions on the measured brightness temperatures; (2) dynamical algorithm tie points to mitigate trends in residual atmospheric, sea ice, and water emission characteristics and inter-sensor differences/biases; and (3) a hybrid sea ice concentration algorithm using the Bristol algorithm over ice and the Bootstrap algorithm in frequency mode over open water. A new sea ice concentration uncertainty algorithm has been developed to estimate the spatial and temporal variability in sea ice concentration retrieval accuracy. A comparison to US National Ice Center sea ice charts from the Arctic and the Antarctic shows that ice concentrations are higher in the ice charts than estimated from the radiometer data at intermediate sea ice concentrations between open water and 100 % ice. The sea ice concentration climate data record is available for download at www.osi-saf.org, including documentation.

Description: The recent thinning and shrinking of the Arctic sea ice cover has increased the interest in seasonal sea ice forecasts. Typical tools for such forecasts are numerical models of the coupled ocean sea ice system such as the North Atlantic/Arctic Ocean Sea Ice Model (NAOSIM). The model uses as input the initial state of the system and the atmospheric boundary condition over the forecasting period. This study investigates the potential of remotely sensed ice thickness observations in constraining the initial model state. For this purpose it employs a variational assimilation system around NAOSIM and the Alfred Wegener Institute's CryoSat-2 ice thickness product in conjunction with the University of Bremen's snow depth product and the OSI SAF ice concentration and sea surface temperature products. We investigate the skill of predictions of the summer ice conditions starting in March for three different years. Straightforward assimilation of the above combination of data streams results in slight improvements over some regions (especially in the Beaufort Sea) but degrades the over-all fit to independent observations. A considerable enhancement of forecast skill is demonstrated for a bias correction scheme for the CryoSat-2 ice thickness product that uses a spatially varying scaling factor.

Description: A comprehensive regional investigation of the Eagle Ford Shale linking productivity to porosity-thickness (PHIH), lithology ([Formula: see text]), pore volume (PHIT), organic matter (TOC), and water-saturation ([Formula: see text]) variations has not been presented to date. Therefore, isopach maps across the Eagle Ford Shale play west of the San Marcos Arch were constructed using thickness and log-calculated attributes such as TOC, [Formula: see text], [Formula: see text], and porosity to identify sweet spots and spatial distribution of these geologic characteristics that influence productivity in shale plays. The Upper Cretaceous Eagle Ford Shale in South Texas is an organic-rich, calcareous mudrock deposited during a second-order transgression of global sea level on a carbonate-dominated shelf updip from the older Sligo and Edwards (Stuart City) reef margins. Lithology and organic-matter deposition were controlled by fluvial input from the Woodbine delta in the northeast, upwelling along the Cretaceous shelf edge, and volcanic and clastic input from distant Laramide events to the north and west. Local oxygen minimum events along the South Texas margin contributed to the preservation of this organic-rich source rock related to the Cenomanian/Turonian global organic anoxic event (OAE2). Paleogeographic and deep-seated tectonic elements controlled the variations of lithology, amount and distribution of organic matter, and facies that have a profound impact on production quality. Petrophysical modeling was conducted to calculate total organic carbon, water saturation, lithology, and porosity of the Eagle Ford Group. Thickness maps, as well as PHIH maps, show multiple sweet spots across the study area. Components of the database were used as variables in kriging, and multivariate statistical analyses evaluated the impact of these variables on productivity. For example, TOC and clay volume ([Formula: see text]) show an inverse relationship that is related to production. Mapping petrophysical parameters across a play serves as a tool to predict geologic drivers of productivity across the Eagle Ford taking the geologic heterogeneity into account.

Description: Disposal of hydraulic fracturing flowback and produced water into Ordovician and Cambrian formations of the Fort Worth Basin (FWB), coupled with an increase in observed seismicity in the Dallas-Fort Worth area, necessitates an understanding of the geologic character of these disposal targets. More than 2 billion barrels (Bbbls) of wastewater have been disposed into the Ordovician Ellenburger Group of the FWB over the past 35 years. Since the implementation of the TexNet Earthquake Catalog (1 January 2017), more than 20 earthquakes of local magnitude ML2.0 or greater have been detected in the area, with depths ranging from 2 to 10 km (approximately 6500–33,000 ft). The cited mechanism for inducement of these earthquakes is reactivation of basement faults due to pore pressure changes, either directly related to proximal disposal or due to disposal volume buildup over time. Here, we present a stratigraphic and petrophysical analysis of FWB disposal targets and their relation to basement rocks. The Ellenburger consists of alternating layers of limestone and dolomite, with minor siliciclastics above the basement toward the Llano Uplift. Matrix porosity averages 〈5 porosity units (p.u.), with higher porosity in dolomitic layers than in limestone. Dolomite dominates at the top of the Ellenburger, which was exposed at the end of both the Lower and Upper Ordovician. Where crystalline basement rocks are penetrated, the composition ranges from granitic to chlorite-bearing metamorphosed lithology. The basement-sediment interface is frequently marked by increased porosity. An updated map of structure on top of basement indicates elevations ranging from outcrop at the Llano Uplift to more than [Formula: see text] ([Formula: see text]) subsea toward the northeast. The disposal zone pore volume is estimated from thickness and porosity maps and ranges from [Formula: see text] to [Formula: see text] billion barrels per square mile ([Formula: see text]).

Description: Localized anthropogenic sources of atmospheric CH4 are highly uncertain and temporally variable. Airborne remote measurement is an effective method to detect and quantify these emissions. In a campaign context, the science yield can be dramatically increased by real-time retrievals that allow operators to coordinate multiple measurements of the most active areas. This can improve science outcomes for both single- and multiple-platform missions. We describe a case study of the NASA/ESA CO2 and MEthane eXperiment (COMEX) campaign in California during June and August/September 2014. COMEX was a multi-platform campaign to measure CH4 plumes released from anthropogenic sources including oil and gas infrastructure. We discuss principles for real-time spectral signature detection and measurement, and report performance on the NASA Next Generation Airborne Visible Infrared Spectrometer (AVIRIS-NG). AVIRIS-NG successfully detected CH4 plumes in real-time at Gb s−1 data rates, characterizing fugitive releases in concert with other in situ and remote instruments. The teams used these real-time CH4 detections to coordinate measurements across multiple platforms, including airborne in situ, airborne non-imaging remote sensing, and ground-based in situ instruments. To our knowledge this is the first reported use of real-time trace-gas signature detection in an airborne science campaign, and presages many future applications. Post-analysis demonstrates matched filter methods providing noise-equivalent (1σ) detection sensitivity for 1.0 % CH4 column enhancements equal to 141 ppm m.

Description: We present the first in-flight results from a novel miniaturised anisotropic magnetoresistive space magnetometer, MAGIC (MAGnetometer from Imperial College), aboard the first CINEMA (CubeSat for Ions, Neutrals, Electrons and MAgnetic fields) spacecraft in low Earth orbit. An attitude-independent calibration technique is detailed using the International Geomagnetic Reference Field (IGRF), which is temperature dependent in the case of the outboard sensor. We show that the sensors accurately measure the expected absolute field to within 2% in attitude mode and 1% in science mode. Using a simple method we are able to estimate the spacecraft's attitude using the magnetometer only, thus characterising CINEMA's spin, precession and nutation. Finally, we show that the outboard sensor is capable of detecting transient physical signals with amplitudes of ~ 20–60 nT. These include field-aligned currents at the auroral oval, qualitatively similar to previous observations, which agree in location with measurements from the DMSP (Defense Meteorological Satellite Program) and POES (Polar-orbiting Operational Environmental Satellites) spacecraft. Thus, we demonstrate and discuss the potential science capabilities of the MAGIC instrument onboard a CubeSat platform.

Description: We introduce the OSI-450, the SICCI-25km and the SICCI-50km climate data records of gridded global sea-ice concentration. These three records are derived from passive microwave satellite data and offer three distinct advantages compared to existing records: first, all three records provide quantitative information on uncertainty and possibly applied filtering at every grid point and every time step. Second, they are based on dynamic tie points, which capture the time evolution of surface characteristics of the ice cover and accommodate potential calibration differences between satellite missions. Third, they are produced in the context of sustained services offering committed extension, documentation, traceability, and user support. The three records differ in the underlying satellite data (SMMR & SSM/I & SSMIS or AMSR-E & AMSR2), in the imaging frequency channels (37 GHz and either 6 or 19 GHz), in their horizontal resolution (25 or 50 km), and in the time period they cover. We introduce the underlying algorithms and provide an evaluation. We find that all three records compare well with independent estimates of sea-ice concentration both in regions with very high sea-ice concentration and in regions with very low sea-ice concentration. We hence trust that these records will prove helpful for a better understanding of the evolution of the Earth's sea-ice cover.