Michael Wojcik

Particulate-Matter Emission Estimates from Agricultural Spring-Tillage Operations Using LIDAR and Inverse Modeling

Abstract. Particulate-matter (PM) emissions from a typical spring agricultural tillage sequence and a strip–till conservation tillage sequence in California’s San Joaquin Valley were estimated to calculate the emissions control efficiency (η) of the strip–till conservation management practice (CMP). Filter-based PM samplers, PM-calibrated optical particle counters (OPCs), and a PM-calibrated light detection and ranging (LIDAR) system were used to monitored upwind and downwind PM concentrations during May and June 2008. Emission rates were estimated through inverse modeling coupled with the filter and OPC measurements and through applying a mass balance to the PM concentrations derived from LIDAR data. Sampling irregularities and errors prevented the estimation of emissions from 42% of the sample periods based on filter samples. OPC and LIDAR datasets were sufficiently complete to estimate emissions and the strip–till CMP η, which were ∼90% for all size fractions in both datasets. Tillage time was also reduced by 84%. Calculated emissions for some operations were within the range of values found in published studies, while other estimates were significantly higher than literature values. The results demonstrate that both PM emissions and tillage time may be reduced by an order of magnitude through the use of a strip–till conservation tillage CMP when compared to spring tillage activities.

Integration of remote lidar and in-situ measured data to estimate particulate flux and emission from tillage operations

Agriculture, through wind erosion, tillage and harvest operations, burning, diesel-powered machinery and animal production operations, is a source of particulate matter emissions. Agricultural sources vary both temporally and spatially due to daily and seasonal activities and inhomogeneous area sources. Conventional point sampling methods originally designed for regional, well mixed aerosols are challenged by the disrupted wind flow and by the small mobile source of the emission encountered in this study. Atmospheric lidar (LIght Detection And Ranging) technology provides a means to derive quantitative information of particulate spatial and temporal distribution. In situ point measurements of particulate physical and chemical properties are used to characterize aerosol physical parameters and calibrate lidar data for unambiguous lidar data processing. Atmospheric profiling with scanning lidar allows estimation of temporal and 2D/3D spatial variations of mass concentration fields for different particulate fractions (PM1, PM2.5, PM10, and TSP) applicable for USEPA regulations. This study used this advanced measurement technology to map PM emissions at high spatial and temporal resolutions, allowing for accurate comparisons of the Conservation Management Practice (CMP) under test. The purpose of this field study was to determine whether and how much particulate emission differs from the conventional method of agricultural fall tillage and combined CMP operations.

Small SWAP 3D imaging flash ladar for small tactical unmanned air systems

The Space Dynamics Laboratory (SDL), working with Naval Research Laboratory (NRL) and industry leaders Advanced Scientific Concepts (ASC) and Hood Technology Corporation, has developed a small SWAP (size, weight, and power) 3D imaging flash ladar (LAser Detection And Ranging) sensor system concept design for small tactical unmanned air systems (STUAS). The design utilizes an ASC 3D flash ladar camera and laser in a Hood Technology gyro-stabilized gimbal system. The design is an autonomous, intelligent, geo-aware sensor system that supplies real-time 3D terrain and target images. Flash ladar and visible camera data are processed at the sensor using a custom digitizer/frame grabber with compression. Mounted in the aft housing are power, controls, processing computers, and GPS/INS. The onboard processor controls pointing and handles image data, detection algorithms and queuing. The small SWAP 3D imaging flash ladar sensor system generates georeferenced terrain and target images with a low probability of false return and <10 cm range accuracy through foliage in real-time. The 3D imaging flash ladar is designed for a STUAS with a complete system SWAP estimate of <9 kg, <0.2 m3 and <350 W power. The system is modeled using LadarSIM, a MATLAB® and Simulink®- based ladar system simulator designed and developed by the Center for Advanced Imaging Ladar (CAIL) at Utah State University. We will present the concept design and modeled performance predictions.

Derivation and Use of Simple Relationships Between Aerodynamic and Optical Particle Measurements

AbstractA simple relationship, referred to as a mass conversion factor (MCF), is presented to convert optically based particle measurements to mass concentration. It is calculated from filter-based samples and optical particle counter (OPC) data on a daily or sample period basis. The MCF allows for greater temporal and spatial mass concentration information than typical filter-based measurements. Results of MCF calculations from several field studies are summarized. Pairwise comparisons from a collocated study with multiple OPCs and mass samplers suggest the minimum variability of the MCF is 5–10%. The variability of the MCF within a sample period during a field study with distributed samplers averaged 17–21%. In addition, the precision of the Airmetrics MiniVol Portable Air Sampler for particulate matter (PM) was typically <10%. Comparisons with federal reference method (FRM) samplers showed that MiniVols yield PM2.5 concentrations essentially equivalent to FRMs with slightly greater deviations from the ...

CELiS (Compact Eyesafe Lidar System): a portable 1.5 μm elastic lidar system for rapid aerosol concentration measurement

CELiS (Compact Eyesafe Lidar System) is a tactical elastic lidar system commissioned by the Strategic Environmental Research and Development Program (SERDP) for the purpose of air quality environmental compliance issues surrounding the offroad use of wheeled and tracked vehicles. A complete CELiS instrument weighs less than 300 lbs., is less than 2 cubic meters in volume and uses 700 W of 120V AC power. CELiS has a working range of better than 2km and a range resolution of 5m.

Estimation of Aerosol Effective Radius by Multiwavelength Elastic Lidar

A new lidar algorithm is presented as part of a technique for estimating aerosol concentration and particle-size distribution (PSD). This technique uses a form of the extended Kalman filter (EKF), wherein the target aerosol is represented as a linear combination of basis-aerosols, so that the estimated PSD of the aerosol is a linear combination of the PSD of the individual basis-aerosols. The state vector of the filter contains the amplitudes of the basis-aerosols, eliminating the need for an intermediate step of estimating scattering coefficients. Point-sensor instruments and Mie scattering theory are used to establish the relationship between basis-aerosols and measured power. The algorithm is demonstrated using both synthetic test data and field measurements of biological and nonbiological aerosols. The estimated PSD allows straightforward calculation of parameters such as volume-fraction concentration and effective radius.

Eye-safe, 243-mJ, rapidly tuned by injection-seeding, near-infrared, optical, parametric, oscillator-based differential-absorption light detection and ranging transmitter

Here, we demonstrate and characterize a high-energy, eye-safe, spectrally narrow, and frequency-agile near-IR optical parametric oscillator (OPO). The injection-seeded, noncritical phase-matched (NCPM) potassium titanyle arsenate (KTA) and ring-cavity OPO was pumped in single longitudinal mode (SLM) at 7 ns full width at half maximum FWHM and 30 Hz, neodymium-doped yttrium aluminum garnet (Nd:YAG), generating 243 mJ per pulse OPO signal output with a conversion efficiency of 27%, spectral linewidth of 157 MHz, and approximately M 2 of 29. Also, we demonstrate a nonmechanical method to switch the frequency of the OPO at a rate of 2 Hz from 1535.036 to 1535.195 nm, which represents the on/off resonances of carbon dioxide, respectively. However, the switching rate can be extended into the MHz range and is limited by the electronics driving the diode laser. Given the performance results of our frequency-agile OPO, this transmitter has great potential as a source in DIAL applications.

Characterization of a quantum cascade laser-based emissivity monitor for CORSAIR

Continuous improvements of quantum cascade laser (QCL) technology have extended the applications in environmental trace gas monitoring, mid-infrared spectroscopy in medicine and life science, law enforcement and homeland security and satellite sensor systems. We present the QCL based emissivity monitor for the CORSAIR blackbody. The emissivity of the blackbody was designed to be better than 0.9999 for the spectral range between 5 to 50μm. To actively monitor changes in blackbody emissivity we employ a QCL-based infrared illumination source. The illumination source consisted of a QCL and thermoelectric cooler (TEC) unit mounted on a copper fixture. The stability of the QCL was measured for 30, 60, and 90s operation time at 1.5A driving current. The temperature distribution along the laser mounting fixture and time dependent system heat dispersion were analyzed. The results were compared to radiative and conductive heat transfer models to define the potential laser operating time and required waiting time to return to initial temperature of the laser mount. The observed cooling behaviour is consistent with a primarily conductive heat transfer mechanism.

Characterization of a Quantum Cascade Laser Based Emissivity Monitor for CORSAIR

The QCL based emissivity monitor which was designed to obtain emissivity uncertainty goal of ±0.00015 (3σ) for the CORSAIR blackbody has been characterized. The laser power stability and temperature distribution of the system are analyzed.

Comparisons of Measurements and Predictions of PM Concentrations and Emission Rates from a Wind Erosion Event

Wind erosion can affect agricultural productivity, soil stability, and air quality. Air quality concerns deal mainly with human health and welfare issues, but are also related to long range transport and deposition of crustal materials. Regulatory standards for ambient levels of particulate matter (PM) with equivalent aerodynamic diameters = 10 µm (PM10) and = 2.5 µm (PM2.5) have been established in many countries in an effort to protect the health and welfare of their citizens. Wind erosion events may lead to high PM levels that exceed air quality standards and are health hazards. Quantifying suspended wind-blown dust emissions and resulting PM concentrations from wind erosion events are, therefore, of significant interest.