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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Photonic methods and technologies for monitoring the ocean and atmosphere

In this paper, we review photonic methods and technologies that are promising for monitoring the ocean and atmosphere and have been implemented mainly in recent years at the Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences. We present results of lidar studies that have made it possible to understand key features of ocean – atmosphere interaction processes under continent – ocean transition conditions, which determine specific features of the atmospheric aerosol distribution, small gaseous components of the atmosphere and its optical characteristics. We consider methods and tools for combined optical and laser fluorescence monitoring of the ocean surface. Particular attention is paid to results of research on remote methods and tools for real-time laser-induced and laser fluorescence environmental monitoring of the ocean, including specialised fibre-optic probes and mobile underwater robotic systems. We present results of the development and investigation of highly sensitive, noise-proof fibre-optic hydro- and seismic/acoustic sensors for remote monitoring of the ocean and robotic systems for underwater laser protection of marine vessels, hydraulic structures and oceanographic instruments against the negative impact of biofouling. (invited paper)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1989

New approaches to the measurement of chlorophyll, related pigments and productivity in the sea

In the 1984 SBIR Call for Proposals, NASA solicited new methods to measure primary production and chlorophyll in the ocean. Biospherical Instruments Inc. responded to this call with a proposal first to study a variety of approaches to this problem. A second phase of research was then funded to pursue instrumentation to measure the sunlight stimulated naturally occurring fluorescence of chlorophyll in marine phytoplankton. The monitoring of global productivity, global fisheries resources, application of above surface-to-underwater optical communications systems, submarine detection applications, correlation, and calibration of remote sensing systems are but some of the reasons for developing inexpensive sensors to measure chlorophyll and productivity. Normally, productivity measurements are manpower and cost intensive and, with the exception of a very few expensive multiship research experiments, provide no contemporaneous data. We feel that the patented, simple sensors that we have designed will provide a cost effective method for large scale, synoptic, optical measurements in the ocean. This document is the final project report for a NASA sponsored SBIR Phase 2 effort to develop new methods for the measurements of primary production in the ocean. This project has been successfully completed, a U.S. patent was issued covering the methodology and sensors, and the first production run of instrumentation developed under this contract has sold out and been delivered.

Booth, C. R.↗
NASA NTRS2001

Remote Sensing of Aerosol and their Radiative Properties from the MODIS Instrument on EOS-Terra Satellite: First Results and Evaluation

The MODIS instrument was launched on the NASA Terra satellite in Dec. 1999. Since last Oct., the sensor and the aerosol algorithm reached maturity and provide global daily retrievals of aerosol optical thickness and properties. MODIS has 36 spectral channels in the visible to IR with resolution down to 250 m. This allows accurate cloud screening and multi-spectral aerosol retrievals. We derive the aerosol optical thickness over the ocean and most of the land areas, distinguishing between fine (mainly man-made aerosol) and coarse aerosol particles. The information is more precise over the ocean where we derive also the effective radius and scattering asymmetry parameter of the aerosol. New methods to derive the aerosol single scattering albedo are also being developed. These measurements are use to track different aerosol sources, transport and the radiative forcing at the top and bottom of the atmosphere. The AErosol RObotic NETwork of ground based radiometers is used for global validation of the satellite derived optical thickness, size parameters and single scattering albedo and measure additional aerosol parameters that cannot be derived from space.

Kaufman, Yoram↗
NASA NTRS1999

Land-Ocean Differences in LIS and OTD Tropical Lightning Observations

Significant differences are known to exist on a global scale between continental and oceanic total lightning regional flash rates, suggesting differences in the properties of convective storms in these regimes. Lightning properties observed by the Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) over land and ocean are compared, limited to analysis over the tropics in order to simplify physical interpretation. We find that the mean flash rates of individual storms over tropical land only exceed those over ocean by a factor of 2 (far less than the observed differences in regional flash rates). However, the average nearest neighbor distance of continental thunderstorms in half that over oceans. Cloud-top lightning optical radiance in oceanic storms is also twice as large as over land, suggesting either more energetic flashes over the oceans or less intervening cloud particles.

Boccippio, Dennis J.↗
NASA NTRS1999

Land-Ocean Differences in LIS and OTD Tropical Lightning Observations

Significant differences are known to exist on a global scale between continental and oceanic total lightning regional flash rates, suggesting differences in the properties of convective storms in these regimes. Lightning properties observed by the Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) over land and ocean are compared, limited to analysis over the tropics in order to simplify physical interpretation. We find that the mean flash rates of individual storms over tropical land only exceed those over ocean by a factor of 2 (far less than the observed differences in regional flash rates). However, the average nearest neighbor distance of continental thunderstorms is half that over oceans. Cloud-top lightning optical radiance in oceanic storms is also twice as large as over land, suggesting either more energetic flashes over the oceans or less intervening cloud particles.

Boccippio, D. J.↗
NASA NTRS1978

Some relationships between Secchi depth and inherent optical properties of natural waters

Relationships between the inherent and optical properties of the ocean (Gorden et al., 1975 and Preisendorfer, 1961) are combined with the Duntley-Preisendorfer equation to show the dependence of these properties on the depth at which a Secchi disk disappears from view. An expression relating the Secchi depth to the limiting contrast of the disk is derived in terms of the average beam attenuation coefficient, the average diffuse attenuation coefficient for downwelling irradiance, the albedo of the disk, and the reflectance functions at the Secchi depth and just below the surface. It is shown that combining Secchi depth observations with other optical properties yields significant information about the constituents of the medium.

Gordon, H. R.↗
NASA NTRS2019

Optical design of the Mapping Imaging Spectrometer for Europa (MISE)

e Mapping Imaging Spectrometer for Europa (MISE) is a high-throughput pushbroom imaging spectrometer designed for NASA’s planned flyby mission to Jupiter’s moon Europa. The MISE design utilizes heritage from previously demonstrated instruments on airborne platforms, while advancing the state of the art to operate within Europa’s challenging environment. The instrument operates at F/1.4 and covers a spectral range from 0.8 to 5 microns with 10 nm spectral sampling. Through high resolution mapping, MISE is designed to identify distributions of organics, salts, acid hydrates, water ice phases, altered silicates, radiolytic compounds, and warm thermal anomalies at global, regional, and local scales. Such distribution maps will help study surface and subsurface geologic processes, and assess the habitability of Europa’s ocean. We discuss the optical specifications and baseline performance of the MISE optical design.

Van Gorp, Byron E.↗
NASA NTRS2016

From Toes to Top-of-the-Atmosphere: Fowler Sneaker Index

Fowler Sneaker Index (FSI), developed by a NASA summer intern, is a new Ocean Color application that facilitates continuous monitoring of environmental conditions in the Chesapeake Bay. It builds on three decades of citizen science data collected by former Maryland State Senator Bernie Fowler, during his yearly "Wade-ins in the Patuxent River". FSI demonstrates how NASA's Earth-observing tools, in combination with a concerned and engaged public, can take science from the tips of our toes-to-top-of the atmosphere and back.

Optics Express↗
NASA NTRS2003

MOBY, A Radiometric Buoy for Performance Monitoring and Vicarious Calibration of Satellite Ocean Color Sensors: Measurement and Data Analysis Protocols

The Marine Optical Buoy (MOBY) is the centerpiece of the primary ocean measurement site for calibration of satellite ocean color sensors based on independent in situ measurements. Since late 1996, the time series of normalized water-leaving radiances L(sub WN)(lambda) determined from the array of radiometric sensors attached to MOBY are the primary basis for the on-orbit calibrations of the USA Sea-viewing Wide Field-of-view Sensor (SeaWiFS), the Japanese Ocean Color and Temperature Sensor (OCTS), the French Polarization Detection Environmental Radiometer (POLDER), the German Modular Optoelectronic Scanner on the Indian Research Satellite (IRS1-MOS), and the USA Moderate Resolution Imaging Spectrometer (MODIS). The MOBY vicarious calibration L(sub WN)(lambda) reference is an essential element in the international effort to develop a global, multi-year time series of consistently calibrated ocean color products using data from a wide variety of independent satellite sensors. A longstanding goal of the SeaWiFS and MODIS (Ocean) Science Teams is to determine satellite-derived L(sub WN)(labda) with a relative combined standard uncertainty of 5 %. Other satellite ocean color projects and the Sensor Intercomparison for Marine Biology and Interdisciplinary Oceanic Studies (SIMBIOS) project have also adopted this goal, at least implicitly. Because water-leaving radiance contributes at most 10 % of the total radiance measured by a satellite sensor above the atmosphere, a 5 % uncertainty in L(sub WN)(lambda) implies a 0.5 % uncertainty in the above-atmosphere radiance measurements. This level of uncertainty can only be approached using vicarious-calibration approaches as described below. In practice, this means that the satellite radiance responsivity is adjusted to achieve the best agreement, in a least-squares sense, for the L(sub WN)(lambda) results determined using the satellite and the independent optical sensors (e.g. MOBY). The end result of this approach is to implicitly absorb unquantified, but systematic, errors in the atmospheric correction, incident solar flux, and satellite sensor calibration into a single correction factor to produce consistency with the in situ data.

Clark, Dennis K.↗
NASA NTRS2014

Assessment of Satellite Ocean Colour Radiometry and Derived Geophysical Products

Standardization of methods to assess and assign quality metrics to satellite ocean color radiometry and derived geophysical products has become paramount with the inclusion of the marine reflectance and chlorophyll-a concentration (Chla) as essential climate variables (ECV; [1]) and the recognition that optical remote sensing of the oceans can only contribute to climate research if and when a continuous succession of satellite missions can be shown to collectively provide a consistent, long-term record with known uncertainties. In 20 years, the community has made significant advancements toward that objective, but providing a complete uncertainty budget for all products and for all conditions remains a daunting task. In the retrieval of marine water-leaving radiance from observed top-of-atmosphere radiance, the sources of uncertainties include those associated with propagation of sensor noise and radiometric calibration and characterization errors, as well as a multitude of uncertainties associated with the modeling and removal of effects from the atmosphere and sea surface. This chapter describes some common approaches used to assess quality and consistency of ocean color satellite products and reviews the current status of uncertainty quantification in the field. Its focus is on the primary ocean color product, the spectrum of marine reflectance Rrs, but uncertainties in some derived products such as the Chla or inherent optical properties (IOPs) will also be considered.

Ocean↗
NASA NTRS2014

Scientific Impact of MODIS C5 Calibration Degradation and C6+ Improvements

The Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) land and atmosphere data sets are scheduled for release in 2014. C6 contains significant revisions of the calibration approach to account for sensor aging. This analysis documents the presence of systematic temporal trends in the visible and near-infrared (500 m) bands of the Collection 5 (C5) MODIS Terra and, to lesser extent, in MODIS Aqua geophysical data sets. Sensor degradation is largest in the blue band (B3) of the MODIS sensor on Terra and decreases with wavelength. Calibration degradation causes negative global trends in multiple MODIS C5 products including the dark target algorithm's aerosol optical depth over land and Ångstrom exponent over the ocean, global liquid water and ice cloud optical thickness, as well as surface reflectance and vegetation indices, including the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). As the C5 production will be maintained for another year in parallel with C6, one objective of this paper is to raise awareness of the calibration-related trends for the broad MODIS user community. The new C6 calibration approach removes major calibrations trends in the Level 1B (L1B) data. This paper also introduces an enhanced C6C calibration of the MODIS data set which includes an additional polarization correction (PC) to compensate for the increased polarization sensitivity of MODIS Terra since about 2007, as well as detrending and Terra- Aqua cross-calibration over quasi-stable desert calibration sites. The PC algorithm, developed by the MODIS ocean biology processing group (OBPG), removes residual scan angle, mirror side and seasonal biases from aerosol and surface reflectance (SR) records along with spectral distortions of SR. Using the multiangle implementation of atmospheric correction (MAIAC) algorithm over deserts, we have also developed a detrending and cross-calibration method which removes residual decadal trends on the order of several tenths of 1% of the top-of-atmosphere (TOA) reflectance in the visible and near-infrared MODIS bands B1-B4, and provides a good consistency between the two MODIS sensors. MAIAC analysis over the southern USA shows that the C6C approach removed an additional negative decadal trend of Terra (Delta)NDVI approx.0.01 as compared to Aqua data. This change is particularly important for analysis of vegetation dynamics and trends in the tropics, e.g., Amazon rainforest, where the morning orbit of Terra provides considerably more cloud-free observations compared to the afternoon Aqua measurements.

Terra and Aqua↗
NASA NTRS2003

An Overview of SIMBIOS Program Activities and Accomplishments

The SIMBIOS Program was conceived in 1994 as a result of a NASA management review of the agency's strategy for monitoring the bio-optical properties of the global ocean through space-based ocean color remote sensing. At that time, the NASA ocean color flight manifest included two data buy missions, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Earth Observing System (EOS) Color, and three sensors, two Moderate Resolution Imaging Spectroradiometers (MODIS) and the Multi-angle Imaging Spectro-Radiometer (MISR), scheduled for flight on the EOS-Terra and EOS-Aqua satellites. The review led to a decision that the international assemblage of ocean color satellite systems provided ample redundancy to assure continuous global coverage, with no need for the EOS Color mission. At the same time, it was noted that non-trivial technical difficulties attended the challenge (and opportunity) of combining ocean color data from this array of independent satellite systems to form consistent and accurate global bio-optical time series products. Thus, it was announced at the October 1994 EOS Interdisciplinary Working Group meeting that some of the resources budgeted for EOS Color should be redirected into an intercalibration and validation program (McClain et al., 2002).

Fargion, Giulietta S.↗
NASA NTRS1980

Optical image and laser slope meter intercomparisons of high-frequency waves

Spectral analyses of optical images of the ocean surface, obtained by a digital video system, are presented and compared with wave data measured simultaneously by the JPL Waverider-mounted laser slope meter. The image analyses, which incorporate several new ideas, provide two-dimensional wave number spectra of slope, covering wavelengths from 10 cm to 10 m. These slope spectra are converted to wave height spectra by a new technique which includes the effects of sky radiance gradients. Space-time spectra are also presented for waves whose frequencies are less than 2 Hz. The JPL slope frequency spectra are compared with image wave number spectra which have been converted to frequency spectra by use of the gravity wave dispersion relation. Results of comparisons between the frequency spectra obtained from the two different measurements show reasonable agreement for frequencies less than 3 Hz.

Lubard, S. C.↗