Vladimir V. Zavyalov

Aglite lidar: a portable elastic lidar system for investigating aerosol and wind motions at or around agricultural production facilities

The Aglite Lidar is a portable scanning lidar that can be quickly deployed at agricultural and other air quality study sites. The purpose of Aglite is to map the concentration of PM 10 and PM 2.5 in aerosol plumes from agricultural and other sources. Aglite uses a high-repetition rate low-pulse energy 3-wavelength YAG laser with photon-counting detection together with a steerable pointing mirror to measure aerosol concentration with high spatial and temporal resolution. Aglite has been used in field campaigns in Iowa, Utah and California. The instrument is described, and performance and lidar sensitivity data are presented. The value of the lidar in aerosol plume mapping is demonstrated, as is the ability to extract wind-speed information from the lidar data.

Aglite lidar: calibration and retrievals of well characterized aerosols from agricultural operations using a three-wavelength elastic lidar

Lidar (LIght Detection And Ranging) provides the means to quantitatively evaluate the spatial and temporal variability of particulate emissions from agricultural activities. AGLITE is a three-wavelength portable scanning lidar system built at the Space Dynamic Laboratory (SDL) to measure the spatial and temporal distribution of particulate concentrations around an agricultural facility. The retrieval algorithm takes advantage of measurements taken simultaneously at three laser wavelengths (355, 532, and 1064 nm) to extract particulate optical parameters, convert these parameters to volume concentration, and estimate the particulate mass concentration of a particulate plume. The quantitative evaluation of particulate optical and physical properties from the lidar signal is complicated by the complexity of particle composition, particle size distribution, and environmental conditions such as heterogeneity of the ambient air conditions and atmospheric aerosol loading. Additional independent measurements of particulate physical and chemical properties are needed to unambiguously calibrate and validate the particulate physical properties retrieved from the lidar measurements. The calibration procedure utilizes point measurements of the particle size distribution and mass concentration to characterize the aerosol and calculate the aerosol parameters. Once calibrated, the Aglite system is able to map the spatial distribution and temporal variation of the particulate mass concentrations of aerosol fractions such as TSP, PM 10, PM 2.5, and PM 1. This ability is of particular importance in the characterization of agricultural operations being evaluated to minimize emissions and improve efficiency, especially for mobile source activities.

Lidar Based Emissions Measurement at the Whole Facility Scale: Method and Error Analysis

Particulate emissions from agricultural sources vary from dust created by operations and animal movement to the fine secondary particulates generated from ammonia and other emitted gases. The development of reliable facility emission data using point sampling methods designed to characterize regional, well-mixed aerosols are challenged by changing wind directions, disrupted flow fields caused by structures, varied surface temperatures, and the episodic nature of the sources found at these facilities. We describe a three-wavelength lidar-based method, which, when added to a standard point sampler array, provides unambiguous measurement and characterization of the particulate emissions from agricultural production operations in near real time. Point-sampled data are used to provide the aerosol characterization needed for the particle concentration and size fraction calibration, while the lidar provides 3D mapping of particulate concentrations entering, around, and leaving the facility. Differences between downwind and upwind measurements provide an integrated aerosol concentration profile, which, when multiplied by the wind speed profile, produces the facility source flux. This approach assumes only conservation of mass, eliminating reliance on boundary layer theory. We describe the method, examine measurement error, and demonstrate the approach using data collected over a range of agricultural operations, including a swine grow-finish operation, an almond harvest, and a cotton gin emission study.

Retrieval of physical properties of particulate emission from animal feeding operations using three-wavelength elastic lidar measurements

Agricultural operations produce a variety of particulates and gases that influence ambient air quality. Lidar (LIght Detection And Ranging) technology provides a means to derive quantitative information of particulate spatial distribution and optical/physical properties over remote distances. A three-wavelength scanning lidar system built at the Space Dynamic Laboratory (SDL) is used to extract optical parameters of particulate matter and to convert these optical properties to physical parameters of particles. This particulate emission includes background aerosols, emissions from the agricultural feeding operations, and fugitive dust from the road. Aerosol optical parameters are retrieved using the widely accepted solution proposed by Klett. The inversion algorithm takes advantage of measurements taken simultaneously at three lidar wavelengths (355, 532, and 1064 nm) and allows us to estimate the particle size distribution. A bimodal lognormal particle size distribution is assumed and mode radius, width of the distribution, and total number density are estimated, minimizing the difference between calculated and measured extinction coefficients at the three lidar wavelengths. The results of these retrievals are then compared with simultaneous point measurements at the feeding operation site, taken with standard equipment including optical particle counters, portable PM10 and PM2.5 ambient air samplers, multistage impactors, and an aerosol mass spectrometer.

Preflight Assessment of the Cross-track Infrared Sounder (CrIS) Performance

The Cross-track Infrared Sounder (CrIS) is a part of the Crosstrack Infrared and Microwave Sounding Suite (CrIMSS) that will be used to produce accurate temperature, water vapor, and pressure profiles on the NPOESS Preparatory Project (NPP) and upcoming Joint Polar Satellite System (JPSS) operational missions. The NPP CrIS flight model has completed sensor qualification, characterization, and calibration and is now integrated with the NPP spacecraft in preparation for the launch. This paper reviews the CrIS performance during thermal vacuum tests, including the spacecraft integration test, and provides a comparison to the AIRS and IASI heritage sensors that it builds upon. The CrIS system consists of the instrument itself and ground-based scientific algorithms. The data reported in this paper was processed with the latest version of the CrIS science sensor data record (SDR) algorithm and thus reflects the performance of the CrIS SDR system. This paper includes the key test results for Noise Equivalent Differential Noise (NEdN), Radiometric Performance, and Spectral Accuracy. The CrIS sensor performance is outstanding and will meet the mission needs for the NPP /JPSS mission. NEdN is one of the key performance tests for the CrIS sensor. The overall NEdN performance for the CrIS in the LWIR, MWIR and SWIR spectral bands is excellent and is comparable or exceeds NEdN performance of AIRS and IASI. Also discussed is the Principal Component Analysis (PCA) approach developed to estimate contribution of random and spectrally correlated noise components to the total NEDN.

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.

Validation assessment model for atmospheric retrievals

A linear mathematical error model for the assessment of validation activity of atmospheric retrievals is presented. The purpose of the validation activity is to assess the actual performance of the remote sensing validated system while in orbit by comparing its measurements to some relevant-validating-data sets. The validating system samples volumes of the atmosphere at times and locations that are different from the ones when and where the validated system makes its own observations. The location of the validating system can be either stationary, e.g. a ground ARM site, or movable, e.g. an aircraft or some other satellites. The true states may be correlated or not. The sampled volumes differ from each other by their location, timing, and size. The validated and validating systems have different vertical resolution and grid, absolute accuracy, and noise level. All the above factors cause apparent differences between the data to be compared. The validation assessment model makes the comparison accurate by allowing for the differences. The model can be used for assessment and interpretation of the validation results when the above mentioned sources of discrepancies are significant, as well as for evaluation of a particular validating data source.

AGLITE: a multiwavelength lidar for aerosol size distributions, flux, and concentrations

We report on the design, construction and operation of a new multiwavelength lidar developed for the Agricultural Research Service of the United States Department of Agriculture and its program on particle emissions from animal production facilities. The lidar incorporates a laser emitting simultaneous, pulsed Nd laser radiation at 355, 532 and 1064 nm at a PRF of 10 kHz. Lidar backscatter and extinction data are modeled to extract the aerosol information. All-reflective optics combined with dichroic and interferometric filters permit all the wavelength channels to be measured simultaneously, day or night, using photon counting by PMTs, an APD, and high speed scaling. The lidar is housed in a transportable trailer for all-weather operation at any accessible site. The laser beams are directed in both azimuth and elevation to targets of interest. We describe application of the lidar in a multidisciplinary atmospheric study at a swine production farm in Iowa. Aerosol plumes emitted from the hog barns were prominent phenomena, and their variations with temperature, turbulence, stability and feed cycle were studied, using arrays of particle samplers and turbulence detectors. Other lidar measurements focused on air motion as seen by long duration scans of the farm region. Successful operation of this lidar confirms the value of multiwavelength, eye-safe lidars for agricultural aerosol measurements.

AGLITE: a multi-wavelength lidar for measuring emitted aerosol concentrations and fluxes and air motion from agricultural facilities

AGLITE is a multi-wavelength lidar developed for the Agricultural Research Service (ARS), United States Department of Agriculture (USDA) and its program on particle emissions from animal production facilities. The lidar transmitter is a 10 kHz pulsed NdYAG laser at 355, 532 and 1064 nm. We analyze lidar backscatter and extinction to extract aerosol physical properties. All-reflective optics and dichroic and interferometric filters permit all wavelengths to be measured simultaneously, day or night, using photon counting by MTs, an APD, and fast data acquisition. The lidar housing is a transportable trailer suitable for all-weather operation at any accessible site. We direct the laser and telescope FOVs to targets of interest in both azimuth and elevation. The lidar has been applied in atmospheric studies at a swine production farm in Iowa and a dairy in Utah. Prominent aerosol plumes emitted from the swine facility were measured as functions of temperature, turbulence, stability and the animal feed cycle. Particle samplers and turbulence detectors were used by colleagues specializing in those fields. Lidar measurements also focused on air motion as seen by scans of the farm volume. The value of multi-wavelength, eye-safe lidars for agricultural aerosol measurements has been confirmed by the successful operation of AGLITE.

Calibration and validation on-orbit plan of the NPOESS Crosstrack Infrared Sounder (CRIS)

Calibration and validation of sensors is important for understanding how a sensor operates during its mission and shows the level of measurements that can be expected. The calibration is an on-going process throughout the mission but is most critical when the complete system comes together and during its initial stage after reaching orbit. Careful planning is required to accurately and efficiently collect data that characterizes the sensors response, process the data in a timely manner to generate results that are useful to mission science, apply the results for processing algorithms, and have a process for improvement as additional information about the sensor becomes available. This paper describes the calibration and validation plan of early on-orbit operations of the Cross-track Infrared Sounder (CrIS). The CrIS sensor is currently integrated on the NPP spacecraft that is scheduled to launch in October 2011.