Matthew Fladeland

Remote sensing for biodiversity science and conservation

Remote-sensing systems typically produce imagery that averages information over tens or even hundreds of square meters – far too coarse to detect most organisms – so the remote sensing of biodiversity would appear to be a fool’s errand. However, advances in the spatial and spectral resolutions of sensors now available to ecologists are making the direct remote sensing of certain aspects of biodiversity increasingly feasible; for example, distinguishing species assemblages or even identifying species of individual trees. In cases where direct detection of individual organisms or assemblages is still beyond our grasp, indirect approaches offer valuable information about diversity patterns. Such approaches derive meaningful environmental parameters from biophysical characteristics that

Methane Emissions from Natural Wetlands in the United States: Satellite-Derived Estimation Based on Ecosystem Carbon Cycling

Abstract Wetlands are an important natural source of methane to the atmosphere. The amounts of methane emitted from inundated ecosystems in the United States can vary greatly from area to area. Seasonal temperature, water table dynamics, and carbon content of soils are principal controlling factors. To calculate the effect of wetlands (and their potential conversion to other land uses) on global greenhouse gas emissions, information on area covered by various wetland types is needed, along with verified projections of spatial variation in net methane emissions. Both of these variables are poorly known, and estimates are largely unavailable at the country level. Nationwide satellite datasets for the coterminous United States (excluding Alaska) have been combined with ecosystem model predictions of monthly net carbon exchange with the atmosphere to produce the first detailed mapping of methane fluxes from natural wetlands on a monthly and annual basis. The Carnegie–Ames–Stanford Approach (CASA) model’s pred...

Estimating carbon budgets for U.S. ecosystems

On a global basis, plants and soils may hold more than twice the amount of carbon present in the atmosphere [Geider et al., 2001]. Under increasing atmospheric carbon dioxide (CO2) concentrations and subsequently warming temperatures, these large biogenic pools may change in size [Cox et al., 2000]. Due to a lack of long-term field studies, there is uncertainty as to whether vegetation and soils will act as a net sink or a source of atmospheric CO2 in coming years. It is certain, however, that no retrospective analysis of the U.S. carbon balance will be possible without a comprehensive historical baseline of the sizes of various ecosystem carbon pools and the variability in their net annual increments.

Unmanned Aerial Mass Spectrometer Systems for In-Situ Volcanic Plume Analysis

AbstractTechnology advances in the field of small, unmanned aerial vehicles and their integration with a variety of sensor packages and instruments, such as miniature mass spectrometers, have enhanced the possibilities and applications of what are now called unmanned aerial systems (UAS). With such technology, in situ and proximal remote sensing measurements of volcanic plumes are now possible without risking the lives of scientists and personnel in charge of close monitoring of volcanic activity. These methods provide unprecedented, and otherwise unobtainable, data very close in space and time to eruptions, to better understand the role of gas volatiles in magma and subsequent eruption products. Small mass spectrometers, together with the world’s smallest turbo molecular pump, have being integrated into NASA and University of Costa Rica UAS platforms to be field-tested for in situ volcanic plume analysis, and in support of the calibration and validation of satellite-based remote sensing data. These new UAS-MS systems are combined with existing UAS flight-tested payloads and assets, such as temperature, pressure, relative humidity, SO2, H2S, CO2, GPS sensors, on-board data storage, and telemetry. Such payloads are capable of generating real time 3D concentration maps of the Turrialba volcano active plume in Costa Rica, while remote sensing data are simultaneously collected from the ASTER and OMI space-borne instruments for comparison. The primary goal is to improve the understanding of the chemical and physical properties of emissions for mitigation of local volcanic hazards, for the validation of species detection and abundance of retrievals based on remote sensing, and to validate transport models. Graphical Abstractᅟ

In situ observations and sampling of volcanic emissions with NASA and UCR unmanned aircraft, including a case study at Turrialba Volcano, Costa Rica

Abstract Scientific knowledge of transient and difficult-to-access airborne volcanic emissions comes primarily from remote sensing observations, and a few in situ data from sporadic heroic or inadvertent airborne encounters. In the past, patchy knowledge of the composition and behaviour of such plumes from explosive volcanic eruptions, and associated drifting ash and gas clouds, have centrally contributed to unwanted and dangerous aircraft encounters that have put crews at risk and, in some cases, greatly damaged aircraft. Thus, improved knowledge of boundary conditions and plume composition, as inputs to both mass retrieval and predictive models for cloud trajectories, would be of benefit. In this paper, we describe how small robotic unmanned aerial vehicles (sUAVs) can address a variety of measurements that are typically beyond the reach of, and sometimes too dangerous for, manned aircraft. The direct measurements and sampling that can be achieved by sUAVs address serious gaps in knowledge of volcanic processes, and provide important validation data for estimations of volcanogenic ash and gas concentrations gleaned using remote sensing techniques. These data, in turn, constrain key proximal and distal boundary conditions for aerosol and gas transport models on which are based a number of decisions and evaluations by hazard responders and regulatory agencies. We briefly describe a case study from our ongoing field study at Turrialba Volcano in Costa Rica, where we are conducting an international campaign of systematic airborne in situ measurements of volcanogenic SO2 and other gases, as well as aerosols, with sUAVs and aerostats (e.g. tethered balloons and kites), in conjunction with data acquisitions by the Advanced Spaceborne Thermal Emission and Reflection (ASTER) radiometer onboard the NASA Terra Earth orbital platform. To our knowledge, this is the first such systematic in situ UAV- and aerostat-based observation programme for SO2 and particulates in a volcanic plume for correlation with orbital data. We preliminarily report good agreement between our UAV/aerostat and ASTER SO2 retrievals within a 5 km radius of the volcano summit, at altitudes of up to 12 500 ft (c. 3850 m) above sea level (asl) for concentrations within the range of 5–20 ppmv (ppm by volume). Additional work continues.

Using the MicroASAR on the NASA SIERRA UAS in the Characterization of Arctic Sea Ice Experiment

The MicroASAR is a flexible, robust SAR system built on the successful legacy of the BYU µSAR. It is a compact LFM-CW SAR system designed for low-power operation on small, manned aircraft or UAS. The NASA SIERRA UAS was designed to test new instruments and support flight experiments. NASA used the MicroASAR on the SIERRA during a science field campaign in 2009 to study sea ice roughness and break-up in the Arctic and high northern latitudes. This mission is known as CASIE-09 (Characterization of Arctic Sea Ice Experiment 2009). This paper describes the MicroASAR and its role flying on the SIERRA UAS platform as part of CASIE-09.

Forest Canopy Structural Properties

The forest canopy is the interface between the land and the atmosphere, fixing atmospheric carbon into biomass and releasing oxygen and water. The arrangement of individual trees, differences in species morphology, the availability of light and soil nutrients, and many other factors determine canopy structure. Overviews of approaches for basic measurements of canopy structure are presented including height (maximum stem height), the fraction of ground overlain by foliage (coverage), and the leaf area per unit ground area (leaf area index, LAI). These measures are important for characterizing estimates of ecosystem productivity and development, as well as for interpreting and validating landscape- to regional-scale estimates of vegetation attributes derived from remote sensing data. The approaches outlined are not exhaustive, but rather identify a range of robust ground- and remote sensing-based methods that capture a suite of metrics useful to the goals of the North American Carbon program: to provide robust, ground-based estimates of C uptake, storage, and flux that can be used for validation and scaling.

Applications of payload directed flight

Next generation aviation flight control concepts require autonomous and intelligent control system architectures that close control loops directly around payload sensors in manner more integrated and cohesive that in traditional autopilot designs. Research into payload and sensor directed flight control at NASA Ames Research Center is investigating new and novel architectures that can satisfy the requirements for next generation control and automation concepts for aviation. Tighter integration between sensor and machine require the definition of specific sensor directed control modes to tie the sensor data directly into a vehicle control structures throughout the entire control architecture, from low-level stability and control loops, to higher level mission planning and scheduling reasoning systems. Payload directed flight system provide guidance, navigation, and control for vehicle platforms hosting a suite of onboard payload sensors, performing missions that require observation of external partially observable systems or phenomena. This paper outlines related research into the field of payload directed flight, and outlines requirements and operating concepts for payload directed flight systems based on identified needs from the scientific literature.

Assuring ground-based detect and avoid for UAS operations

One of the goals of the Marginal Ice Zones Observations and Processes Experiment (MIZOPEX) NASA Earth science mission was to show the operational capabilities of Unmanned Aircraft Systems (UAS) when deployed on challenging missions, in difficult environments. Given the extreme conditions of the Arctic environment where MIZOPEX measurements were required, the mission opted to use a radar to provide a ground-based detect-and-avoid (GBDAA) capability as an alternate means of compliance (AMOC) with the see-and-avoid federal aviation regulation. This paper describes how GBDAA safety assurance was provided by interpreting and applying the guidelines in the national policy for UAS operational approval. In particular, we describe how we formulated the appropriate safety goals, defined the processes and procedures for system safety, identified and assembled the relevant safety verification evidence, and created an operational safety case in compliance with Federal Aviation Administration (FAA) requirements. To the best of our knowledge, the safety case, which was ultimately approved by the FAA, is the first successful example of non-military UAS operations using GBDAA in the U.S. National Airspace System (NAS), and, therefore, the first nonmilitary application of the safety case concept in this context.

Methane emissions from a Californian landfill, determined fromairborne remote sensing and in-situ measurements

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 ktCH4 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 ktCH4 yr−1 (±2.8 ktCH4 yr−1). The US Environmental Protection Agency (EPA) reported inventory value is 11.5 ktCH4 yr−1 for 2014, on average 2.8 ktCH4 yr−1 (±1.6 ktCH4 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. Published by Copernicus Publications on behalf of the European Geosciences Union. 3430 S. Krautwurst et al.: Landfill emissions