Hyperspectral Imaging for Fine to Medium Scale Applications in Environmental Sciences

The aim of the Special Issue “Hyperspectral Imaging for Fine to Medium Scale Applications in Environmental Sciences” was to present a selection of innovative studies using hyperspectral imaging (HSI) in different thematic fields. This intention reflects the technical developments in the last three decades, which have brought the capacity of HSI to provide spectrally, spatially and temporally detailed data, favoured by e.g., hyperspectral snapshot technologies, miniaturized hyperspectral sensors and hyperspectral microscopy imaging. The present book comprises a suite of papers in various fields of environmental sciences—geology/mineral exploration, digital soil mapping, mapping and characterization of vegetation, and sensing of water bodies (including under-ice and underwater applications). In addition, there are two rather methodically/technically-oriented contributions dealing with the optimized processing of UAV data and on the design and test of a multi-channel optical receiver for ground-based applications. All in all, this compilation documents that HSI is a multi-faceted research topic and will remain so in the future

An Examination of Environmental Applications for Uncooled Thermal Infrared Remote Sensing Instruments

Advancements in system design for thermal instruments require assessment of potential environmental applications and appropriate data processing techniques. A novel multi-band thermal imaging system was proposed by DRS Leonardo for the National Aeronautics and Space Administration Earth Science Technology Office Instrument Incubator Program, for which these criteria were assessed. The Multi-Band Uncooled Radiometer Imager (MURI) is a six spectral channel instrument designed to collect images in the thermal infrared, specifically in the range of 7.5 to 12.5 μm. The work detailed in this thesis characterizes the ability of a thermal imager with an uncooled microbolometer focal plane array to provide valuable data for environmental science applications. Here, a pair of studies using simulated data demonstrates the ability of a multispectral instrument such as MURI to detect enhanced levels of atmospheric methane using a novel approach that performs similarly to a state of the art algorithm when applied to MURI data. The novel method is evaluated using a controlled concentration simulated dataset to determine the extent of its detection capabilities and its dependence on atmospheric conditions. The methane investigations reveal the system is capable of detecting a 20 m thick CH4 plume of 10-20 ppm above background levels when column water vapor is low using both the NDMI and matched filter approaches. Additionally, land surface temperature and emissivity retrieval techniques were applied to experimental MURI data recorded during initial test flights to assess their accuracy with MURI data. Utilizing split window and Temperature Emissivity Separation make this examination distinct as this establishes that proven methods can be applied to uncooled multiband imager data. Application of these methods to MURI data demonstrated the system is capable of temperature retrievals with Root Mean Square Errors of less than 1 K to measured reference values and surface emissivity retrievals within 2% of reference database values. The definition and application of the Normalized Differential Methane Index in this thesis demonstrates a novel approach for detection of enhanced plumes of methane utilizing a multispectral system with only a single band allocated to methane absorption features

Overview of Intercalibration of Satellite Instruments

Intercalibration of satellite instruments is critical for detection and quantification of changes in the Earth’s environment, weather forecasting, understanding climate processes, and monitoring climate and land cover change. These applications use data from many satellites; for the data to be interoperable, the instruments must be cross-calibrated. To meet the stringent needs of such applications, instruments must provide reliable, accurate, and consistent measurements over time. Robust techniques are required to ensure that observations from different instruments can be normalized to a common scale that the community agrees on. The long-term reliability of this process needs to be sustained in accordance with established reference standards and best practices. Furthermore, establishing physical meaning to the information through robust Système International d’unités traceable calibration and validation (Cal/Val) is essential to fully understand the parameters under observation. The processes of calibration, correction, stabilitymonitoring, and quality assurance need to be underpinned and evidenced by comparison with “peer instruments” and, ideally, highly calibrated in-orbit reference instruments. Intercalibration between instruments is a central pillar of the Cal/Val strategies of many national and international satellite remote sensing organizations. Intercalibration techniques as outlined in this paper not only provide a practical means of identifying and correcting relative biases in radiometric calibration between instruments but also enable potential data gaps between measurement records in a critical time series to be bridged. Use of a robust set of internationally agreed upon and coordinated intercalibration techniques will lead to significant improvement in the consistency between satellite instruments and facilitate accurate monitoring of the Earth’s climate at uncertainty levels needed to detect and attribute the mechanisms of change. This paper summarizes the state-of-the-art of postlaunch radiometric calibration of remote sensing satellite instruments through intercalibration

Overview of Intercalibration of Satellite Instruments

Intercalibration of satellite instruments is critical for detection and quantification of changes in the Earth’s environment, weather forecasting, understanding climate processes, and monitoring climate and land cover change. These applications use data from many satellites; for the data to be interoperable, the instruments must be cross-calibrated. To meet the stringent needs of such applications, instruments must provide reliable, accurate, and consistent measurements over time. Robust techniques are required to ensure that observations from different instruments can be normalized to a common scale that the community agrees on. The long-term reliability of this process needs to be sustained in accordance with established reference standards and best practices. Furthermore, establishing physical meaning to the information through robust Système International d’unités traceable calibration and validation (Cal/Val) is essential to fully understand the parameters under observation. The processes of calibration, correction, stabilitymonitoring, and quality assurance need to be underpinned and evidenced by comparison with “peer instruments” and, ideally, highly calibrated in-orbit reference instruments. Intercalibration between instruments is a central pillar of the Cal/Val strategies of many national and international satellite remote sensing organizations. Intercalibration techniques as outlined in this paper not only provide a practical means of identifying and correcting relative biases in radiometric calibration between instruments but also enable potential data gaps between measurement records in a critical time series to be bridged. Use of a robust set of internationally agreed upon and coordinated intercalibration techniques will lead to significant improvement in the consistency between satellite instruments and facilitate accurate monitoring of the Earth’s climate at uncertainty levels needed to detect and attribute the mechanisms of change. This paper summarizes the state-of-the-art of postlaunch radiometric calibration of remote sensing satellite instruments through intercalibration

Design Analysis of a Sapce Based Chromotomographic Hyperspectral Imaging Experiment

This research develops the design of several components and/or systems for an experimental space-based chromotomographic hyperspectral imager that is being built by the Air Force Institute of Technology. The design work includes three separate topics. The first topic was the development of a structure utilizing finite element analysis and eigenanalysis for the ground-based version of the chromotomographic experiment (CTEx). The ground-based experiment was performed as a risk mitigation measure for the space-based experiment. The second topic includes a design review of a contractor\u27s proposed off-axis Mersenne telescope for the space-based chromotomographic hyperspectral imager. The work included the creation of preliminary verification requirements from the contract and sub- sequent analysis of the telescope design based on those requirements. The third topic addressed was a trade study of on-orbit focus, alignment, and calibration schemes for the space-based version of CTEx. The selected imaging focusing method entails imaging Earth-based sodium lights at night while stepping through several focus settings. The optimal focus setting shows the clearest sodium spectral features. The critical alignment concerns were identified as the alignment of the prism and of the collimated light onto the prism. The space-based CTEx utilizes three separate calibration methods involving vicarious Earth-based targets, and on-board laser diodes and spectral filters. The results of the research varied by topic. For the first topic, a structural assembly was successfully fabricated that allowed the goals of the ground-based CTEx to be met, validating the design approach. The design review for the second topic was successful with the contractor\u27s telescope design currently undergoing fabrication with delivery in May 2010. For the third topic, applicable methods and procedures were developed for the space-based CTEx

13 th International Workshop on Greenhouse Gas Measurements from Space : Book of Abstracts

The 13th International Workshop on Greenhouse Gas Measurements from Space (IWGGMS) will be held on 6-8 June, 2017, at the University of Helsinki in Helsinki, Finland. The workshop is organised by the Finnish Meteorological Institute with support from the University of Helsinki. The workshop gathers together more than 160 scientists from the EU, USA, Japan, China, Australia, Canada, and Russia. This report is the official abstract book of the workshop. Background. Success in space-based global measurement of greenhouse gases, such as carbon dioxide and methane, is critical for advancing the understanding of carbon cycle. The recent developments in observations and in interpreting the data are very promising. Space-based greenhouse gas measurement, however, poses a wide array of challenges, many of which are complex and thus demand close international cooperation. The goal of the workshop is to review the state of the art in remote sensing of CO 2 , CH 4 , and other greenhouse gases from space including the current satellite missions, missions to be launched in the near future, emission hot spots on regional and global scales, process studies and interactions of carbon cycle and climate, pre-flight and on-orbit instrument calibration techniques, retrieval algorithms and uncertainty quantification, validation methods and instrumentation, related ground-based, shipboard, and airborne measurements, and flux inversion from space based measurements. The workshop is part of the programme for the centenary of Finland's independence in 2017. The workshop is also one of the activities arranged by the Finnish Meteorological Institute to support Finland's chairmanship of the Arctic Council, 2017 - 2019. The workshop is sponsored by the Finnish Meteorological Institute, the University of Helsinki, the European Space Agency, the City of Helsinki, the Federation of Finnish Learned Societies, and ABB Inc

Summaries of the Third Annual JPL Airborne Geoscience Workshop. Volume 1: AVIRIS Workshop

This publication contains the preliminary agenda and summaries for the Third Annual JPL Airborne Geoscience Workshop, held at the Jet Propulsion Laboratory, Pasadena, California, on 1-5 June 1992. This main workshop is divided into three smaller workshops as follows: (1) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on June 1 and 2; (2) the Thermal Infrared Multispectral Scanner (TIMS) workshop, on June 3; and (3) the Airborne Synthetic Aperture Radar (AIRSAR) workshop, on June 4 and 5. The summaries are contained in Volumes 1, 2, and 3, respectively

Satellite estimation of biophysical parameters for ecological models.

Ecological models are central to understanding of hydrological and carbon cycles. These models need input from Earth Observation data to function at regional to global scales. Requirements of these models and the satellite missions designed to fulfill them are reviewed to asses the present situation. The aim is to establish a better informed framework for the design and development of future satellite missions to meet the needs of ecological modellers. Key land surface parameters that can potentially be derived by remote sensing are analysed - leaf area index, leaf chlorophyll content, the fraction of photosynthetically-active radiation absorbed by the canopy and the fractional cover - as well as the aerosol optical thickness. Three coupled models - PROSPECT, FLIGHT and 6S - are used to simulate top of the atmosphere reflectances observed in a number of viewing directions and spectral wavebands within the visible and near-infrared domains. A preliminary study provides a sensitivity analysis of the top of the atmosphere reflectances to the input parameters and to the viewing angles. Finally, a methodology that links ecological model requirements to satellite instrument capabilities is presented. The three coupled models - PROSPECT, FLIGHT and 6S - are inverted using a simple technique based on look-up tables (LUTs). The LUT is used to estimate canopy biophysical variables from remotely-sensed data observed at the top of the atmosphere with different directional and spectral sampling configurations. The retrieval uncertainty is linked with the instrument radiometric accuracy by analysing the impact of different levels of radiometric noise at the input. The parameters retrieved in the inversion are used to drive two land-surface parameterization models, Biome-BGC and JULES. The effects of different configurations and of the radiometric noise on the NPP estimated are analysed. The technique is applied to evaluate desirable sensor characteristics for driving models of boreal forest productivity. The results are discussed in view of the definition of future satellites and the selection of the best measurement configuration for accurate estimation of canopy characteristics

Study of cloud properties from single-scattering, radiative forcing, and retrieval perspectives

This dissertation reports on three different yet related topics in light scattering computation, radiative transfer simulation, and remote sensing implementation, regarding the cloud properties and the retrieval of cloud properties from satellite-based infrared radiometric measurements. First, the errors associated with the use of circular cylinders as surrogates for hexagonal columns in computing the optical properties of pristine ice crystals at infrared (8-12 µm) wavelengths are investigated. It is found that the differences between the results for circular cylinders and hexagonal columns are on the order of a few percent at infrared wavelengths. Second, investigated in this dissertation are the outgoing broadband longwave and window channel radiances at the top-of-atmosphere under clear-sky conditions on the basis of the data acquired by the Cloud and the Earth's Radiant Energy System (CERES) instrument onboard the NASA Terra satellite platform. Based on the comparison of the observed broadband radiances with those obtained from rigorous radiative transfer simulations, it is found that the theoretical results tend to be larger than their measured counterparts. Extensive sensitivity studies regarding the uncertainties of various parameters were carried out. Within the considered uncertainties of various factors, the computed radiances are still larger than the observed radiances if thin cirrus clouds are excluded. Thus, a potential cause for the differences could be associated with the presence of thin cirrus clouds whose visible optical thickness is smaller than approximately 0.3. Third, presented in this dissertation is an illustration of the application of hyperspectral infrared channel observations to the retrieval of the cloud properties. Specifically, the hyperspectral measurements acquired from the Atmospheric Infrared Sounder (AIRS) aboard the NASA Aqua platform are used to infer cloud top pressure, effective cloud amount, cloud thermodynamic phase, cloud optical thickness, and the effective size of cloud particles. The AIRS-based retrievals are compared with the counterparts of the operational cloud products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The two retrievals agree reasonably well except for the retrieved cloud effective particle size. Furthermore, the diurnal and seasonal contrasts of cloud properties are also investigated on the basis of the cloud properties retrieved from the AIRS data