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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 1,585 records · Page 88
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Cloud-to-ground lightning and rainfall volumes in mesoscale convective systems

The relationship between cloud-to-ground lightning and surface rainfall estimates for the southern Great Plains during the spring 1985 PRE-STORM project is examined to determine if consistent relationships between these two parameters exist in this area. Understanding the relationships will permit the development of lightning-rainfall algorithms applicable to this region and other climatic areas. The radar data collected during this project provided good temporal and spatial coverage of several mesoscale convective systems from their incipient through mature stages and on to decay with temporal sampling at 10 to 12 minute intervals.

Nielsen, Kurt E.↗
NASA NTRS1991

High altitude airborne remote sensing mission using the advanced microwave precipitation radiometer (AMPR)

The advanced microwave precipitation radiometer (AMPR) is an airborne multichannel imaging radiometer used to better understand how the earth's climate structure works. Airborne data results from the October 1990 Florida thunderstorm mission in Jacksonville, FL, are described. AMPR data on atmospheric precipitation in mesoscale storms were retrieved at 10.7, 19.35, 37.1, and 85.5 GHz onboard the ER-2 aircraft at an altitude of 20 km. AMPR's three higher-frequency data channels were selected to operate at the same frequencies as the spaceborne special sensor microwave/imager (SSM/I) presently in orbit. AMPR uses two antennas to receive the four frequencies: the lowest frequency channel uses a 9.7-in aperture lens antennas, while the three higher-frequency channels share a separate 5.3-in aperture lens antenna. The radiometer's temperature resolution performance is summarized.

Galliano, J.↗
NASA NTRS1993

New parameterizations and sensitivities for simple climate models

This paper presents a reexamination of the earth radiation budget parameterization of energy balance climate models in light of data collected over the last 12 years. The study consists of three parts: (1) an examination of the infrared terrestrial radiation to space and its relationship to the surface temperature field on time scales from 1 month to 10 years; (2) an examination of the albedo of the earth with special attention to the seasonal cycle of snow and clouds; (3) solutions for the seasonal cycle using the new parameterizations with special attention to changes in sensitivity. While the infrared parameterization is not dramatically different from that used in the past, the albedo in the new data suggest that a stronger latitude dependence be employed. After retuning the diffusion coefficient the simulation results for the present climate generally show only a slight dependence on the new parameters. Also, the sensitivity parameter for the model is still about the same (1.25 C for a 1 percent increase of solar constant) for the linear models and for the nonlinear models that include a seasonal snow line albedo feedback (1.34 C). One interesting feature is that a clear-sky planet with a snow line albedo feedback has a significantly higher sensitivity (2.57 C) due to the absence of smoothing normally occurring in the presence of average cloud cover.

Graves, Charles E.↗
NASA NTRS1995

Use of midlatitude soil moisture and meteorological observations to validate soil moisture simulations with biosphere and bucket models

Soil moisture observations in sites with natural vegetation were made for several decades in the former Soviet Union at hundreds of stations. In this paper, the authors use data from six of these stations from different climatic regimes, along with ancillary meteorological and actinometric data, to demonstrate a method to validate soil moisture simulations with biosphere and bucket models. Some early and current general circulation models (GCMs) use bucket models for soil hydrology calculations. More recently, the Simple Biosphere Model (SiB) was developed to incorporate the effects of vegetation on fluxes of moisture, momentum, and energy at the earth's surface into soil hydrology models. Until now, the bucket and SiB have been verified by comparison with actual soil moisture data only on a limited basis. In this study, a Simplified SiB (SSiB) soil hydrology model and a 15-cm bucket model are forced by observed meteorological and actinometric data every 3 h for 6-yr simulations at the six stations. The model calculations of soil moisture are compared to observations of soil moisture, literally 'ground truth,' snow cover, surface albedo, and net radiation, and with each other. For three of the stations, the SSiB and 15-cm bucket models produce good simulations of seasonal cycles and interannual variations of soil moisture. For the other three stations, there are large errors in the simulations by both models. Inconsistencies in specification of field capacity may be partly responsible. There is no evidence that the SSiB simulations are superior in simulating soil moisture variations. In fact, the models are quite similar since SSiB implicitly has a bucket embedded in it. One of the main differences between the models is in the treatment of runoff due to melting snow in the spring -- SSiB incorrectly puts all the snowmelt into runoff. While producing similar soil moisture simulations, the models produce very different surface latent and sensible heat fluxes, which would have large effects on GCM simulations.

Robock, Alan↗
NASA NTRS1996

Survey Plan For Characterization of the Subsurface Underlying the National Aeronautics and Space Administration's Marshall Space Flight Center in Huntsville, Alabama

Topic considered include: survey objectives; technologies for non-Invasive imaging of subsurface; cost; data requirements and sources; climatic condition; hydrology and geology; chemicals; magnetometry; electrical(resistivity, potential); optical-style imaging; reflection/refraction seismics; gravitometry; photo-acoustic activation;well drilling and borehole analysis; comparative assessment matrix; ground sensors; choice of the neutron sources; logistic of operations; system requirements; health and safety plans.

Source record↗
NASA NTRS1998

development of a medium repetition rate (10 Hz - 500 Hz) diode pumped laser transmitter for airborne scanning altimetry

Since the late 1980's, NASA has developed several small, all-solid state lasers of low repetition rates for use as transmitters in prototype LIDAR and raster scanned altimetry retrieval systems. Our early laser transmitters were developed for high resolution airborne altimetry which employed cavity dumping techniques to produce a pulse shape with a 1 ns rise time. The first such laser was the SUMR (Sub-millimeter resolution) transmitter which used a side pumped, D-shaped half-rod of Nd:YAG for the oscillator active media and produced approximately 3 ns pulses of 100 micro-J energy at a 40 Hz repetition rate. (Coyle and Blair, 1993; Coyle et al., 1995) After several upgrades to improve rep rate and pulse energy, the final version produced 1.2 mJ pulses at 120 Hz with a 3.7 ns pulse width. The laser has become known as SPLT (Sharp Pulsed Laser Transmitter), and has flown successfully on a variety of airborne altimetry missions. (Coyle and Blair, 1995; Blair et al., 1994) From building these systems, we have accrued valuable experience in delivering field-deployable lasers and have become aware of the advantages and disadvantages of employing new technologies. For example, even though the laser's main operating environment is in a "cold" aircraft during flight, the laser must still operate in very warm temperatures. This is important if the mission is based in the desert or a tropical climate since ground calibration data from stationary targets must be gathered before and after each data flight. Because conductive cooling is much more convenient than closed loop water flow, achieving the highest possible laser efficiency is becoming a high priority when designing a flight laser. This is especially true for lasers with higher pulse energies and repetition rates which are needed for high altitude scanning altimeters and LIDARs.

Coyle, D. Barry↗
NASA NTRS2000

Earth Rotation and Coupling to Changes in Atmospheric Angular Momentum

The research supported under the contract dealt primarily with: (a) the mechanisms responsible for the exchange of angular momentum between the solid Earth and atmosphere; (b) the quality of the data sets used to estimate atmospheric angular momentum; and (c) the ability of these data and of global climate models to detect low-frequency signals in the momentum and, hence, circulation of the atmosphere. Three scientific papers reporting on the results of this research were produced during the course of the contract. These papers identified the particular torques responsible for the peak in atmospheric angular momentum and length-of-day during the 1982-93 El Nino event, and, more generally, the relative roles of torques over land and ocean in explaining the broad spectrum of variability in the length-of-day. In addition, a tendency for interannual variability in atmospheric angular momentum to increase during the last several decades of the 20th century was found in both observations and a global climate model experiment.

Rosen, Richard D.↗
NASA NTRS1993

Observing Global Ocean Circulation From Space: The First Year's Results From the TOPEX/POSEIDON Mission

The joint U.S./France TOPEX/Poseidon satellite was launched on August 10, 1992, and became operational 42 days later. The major goal of the mission is to use a radar altimeter system for making precise measurements of the height of the sea surface for the study of the dynamics of large-scale ocean circulation, which is a key to understanding global climate change. Additionally, the data are used for studying ocean tides and marine geophysics. The radar altimeter also measures wave height and wind speed. The mission is being conducted to optimize the sea surface height measurements for a minimum of three years. The primary objective of the first six months of the mission was to calibrate and validate the mission's measurements. The verification results indicate that all the measurement objectives have been met...

Fu, L. -L.↗
NASA NTRS1993

Observing Global Ocean Circulation From Space: The First Year's Results From the TOPEX/POSEIDON Mission

The joint U.S./France TOPEX/Poseidon satellite was launched on August 10, 1992, and became operational 43 days later. The major goal of the mission is to use a radar altimeter system for making precise measurements of the height of the sea surface for the study of the dynamics of large-scale ocean circulation, which is a key to understanding global climate change. Additionally, the data are used for studying ocean tides and marine geophysics. The radar altimeter also measures wave height and wind speed. The mission is being conducted to optimize the sea surface height measurements for a minimum of three years. The primary objective of the first six months of the mission was to calibrate and validate the mission's measurements...

Fu, L. -L.↗
NASA NTRS2010

Application of Satellite Observations to Manage Natural Disasters in the Lake Victoria Basin

Lake Victoria, the second largest fresh water lake in the Eastern part of Africa is a vital natural resource for the economic well being and prosperity of over 30 million people located in riparian regions of Uganda, Kenya and Tanzania. It covers a large area of about 68,870 km2 and produces a GDP of about US $30 billion per year. The region is also very much prone to natural disasters such as severe floods during heavy precipitation periods in the Eastern part of Africa. In addition to floods, the precipitation also produces large infestations of mosquito larvae due to the standing water in many areas. This further causes multiple vector borne diseases such as Malaria, Rift Valley Fever and more. These problems are of serious concern and require active and aggressive surveillance and management to minimize the loss of human and animal lives and property damage. Satellite imagery and observations along with the in situ measurements provide a great tool to analyze and study this area and inform the policy makers to make calculated policy decisions which are more beneficial to the environment. Recently, NASA and USAID have joined forces with the Regional Center for Mapping of Resources for Development (RCMRD) located in Nairobi, Kenya to utilize multiple NASA sensors such as TRMM, SRTM and MODIS to develop flood potential maps for the Lake Victoria Basin. The idea is to generate a flood forecasts and "nowcasts" that can be sent to the disaster management organizations of Uganda, Kenya, and Tanzania. Post flood event satellite imagery is becoming a common tool to assess the areas inundated by flooding. However, this work is unique undertaking by utilizing land imaging and atmospheric satellites to build credible flood potential maps. At same time, we are also studying the potential occurrence and spread of Rift Valley Fever disease based on the short term climate records and precipitation data. These activities require multi-nation coordination and agreements and multiple operational agencies within each respective country. It also requires credible in situ data such as precipitation, river flow rates and lake levels to further validate the global and regional Hood models and algorithms. This also requires a considerable amount of training and capacity building for the RCMRD experts who will help us validate the model results and eventually transition it for operational use. In a final analysis, Disaster management and humanitarian aid organizations need accurate and timely information for making decisions regarding deployment of relief teams and emergency supplies during major floods. Flood maps based on the use of satellite data have proven extremely valuable to such organizations for identifying the location, extent, and severity of these events. However, despite extraordinary efforts on the part of remote sensing data providers to rapidly deliver such maps, there is typically a delay of several days or even weeks from the on-set of flooding until such maps are available to the disaster management community. This paper summarizes efforts at NASA to address this problem through development of an integrated and automated process of a) flood forecasting b) flood detection, c) satellite data acquisition, d) rapid Hood mapping and distribution, and e) validation of Hood forecasting and detection products.

Habib, Shahid↗
NASA NTRS2010

Data Access Services that Make Remote Sensing Data Easier to Use

This slide presentation reviews some of the processes that NASA uses to make the remote sensing data easy to use over the World Wide Web. This work involves much research into data formats, geolocation structures and quality indicators, often to be followed by coding a preprocessing program. Only then are the data usable within the analysis tool of choice. The Goddard Earth Sciences Data and Information Services Center is deploying a variety of data access services that are designed to dramatically shorten the time consumed in the data preparation step. On-the-fly conversion to the standard network Common Data Form (netCDF) format with Climate-Forecast (CF) conventions imposes a standard coordinate system framework that makes data instantly readable through several tools, such as the Integrated Data Viewer, Gridded Analysis and Display System, Panoply and Ferret. A similar benefit is achieved by serving data through the Open Source Project for a Network Data Access Protocol (OPeNDAP), which also provides subsetting. The Data Quality Screening Service goes a step further in filtering out data points based on quality control flags, based on science team recommendations or user-specified criteria. Further still is the Giovanni online analysis system which goes beyond handling formatting and quality to provide visualization and basic statistics of the data. This general approach of automating the preparation steps has the important added benefit of enabling use of the data by non-human users (i.e., computer programs), which often make sub-optimal use of the available data due to the need to hard-code data preparation on the client side.

Lynnes, Christopher↗
NASA NTRS2011

The Solar Spectral Irradiance as a Function of the Mg II Index for Atmosphere and Climate Modelling

In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly alpha-400 nm region, and its variability, based on the Mg II index and neutron monitor. Measurements of the solar spectral irradiance available in the literature have been made with different instruments at different times and different spectral ranges. However, climate studies require harmonized data sets. This new approach has the advantage of being independent of the absolute calibration and aging of the instruments. First, the Mg II index is derived using solar spectra from Ly alpha (121 nm) to 410 nm measured from 1978 to 2010 by several space missions. The variability of the spectra with respect to a chosen reference spectrum as a function of time and wavelength is scaled to the derived Mg II index. The set of coefficients expressing the spectral variability can be applied to the chosen reference spectrum to reconstruct the solar spectra within a given time frame or Mg II index values. The accuracy of this method is estimated using two approaches: by direct comparison with particular cases where solar spectra are available from independent measurements, and by calculating the standard deviation between the measured spectra and their reconstruction. From direct comparisons with measurements we obtain an accuracy of about 1 to 2 %, which degrades towards Ly alpha. In a further step, we extend our solar spectral irradiance reconstruction back to the Maunder Minimum introducing the relationship between the Mg II index and the neutron monitor data. Consistent measurements of the Mg II index are not available prior to 1978. However, we observe that over the last three solar cycles, the Mg II index shows strong correlation with the modulation potential determined from the neutron monitor data. Assuming that this correlation can be applied to the past, we reconstruct the Mg II index from the modulation potential back to the Maunder Minimum, and obtain the corresponding solar spectral irradiance reconstruction back to that period. As there is no direct measurement of the spectral irradiance for this period we discuss this methodology in light of the other proposed approaches available in the literature. The use of the cosmogenic isotope data provides a major advantage: it provides information about the solar activity over several thousands years. Using technology of today we can calibrate the solar irradiance against the activity and thus reconstruct it for the times when cosmogenic isotope data are available. This calibration can be re-accessed at any time, if necessary.

Thuillier, Gerard↗
NASA NTRS2013

Where Does the Irrigation Water Go? An Estimate of the Contribution of Irrigation to Precipitation Using MERRA

Irrigation is an important human activity that may impact local and regional climate, but current climate model simulations and data assimilation systems generally do not explicitly include it. The European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) shows more irrigation signal in surface evapotranspiration (ET) than the Modern-Era Retrospective Analysis for Research and Applications (MERRA) because ERA-Interim adjusts soil moisture according to the observed surface temperature and humidity while MERRA has no explicit consideration of irrigation at the surface. But, when compared with the results from a hydrological model with detailed considerations of agriculture, the ET from both reanalyses show large deficiencies in capturing the impact of irrigation. Here, a back-trajectory method is used to estimate the contribution of irrigation to precipitation over local and surrounding regions, using MERRA with observation-based corrections and added irrigation-caused ET increase from the hydrological model. Results show substantial contributions of irrigation to precipitation over heavily irrigated regions in Asia, but the precipitation increase is much less than the ET increase over most areas, indicating that irrigation could lead to water deficits over these regions. For the same increase in ET, precipitation increases are larger over wetter areas where convection is more easily triggered, but the percentage increase in precipitation is similar for different areas. There are substantial regional differences in the patterns of irrigation impact, but, for all the studied regions, the highest percentage contribution to precipitation is over local land.

ERA-Interim↗
NASA NTRS2016

Kennedy Space Center Five Year Sustainability Plan

The Federal Government is committed to following sustainable principles. At its heart, sustainability integrates environmental, societal and economic solutions for present needs without compromising the ability of future generations to meet their needs. Building upon its pledge towards environmental stewardship, the Administration generated a vision of sustainability spanning ten goals mandated within Executive Order (EO) 13693, Planning for Federal Sustainability in the Next Decade. In November 2015, the National Aeronautics and Space Administration (NASA) responded to this EO by incorporating it into a new release of the NASA Strategic Sustainability Performance Plan (SSPP). The SSPP recognizes the importance of aligning environmental practices in a manner that preserves, enhances and strengthens NASA's ability to perform its mission indefinitely. The Kennedy Space Center (KSC) is following suit with KSC's Sustainability Plan (SP) by promoting, maintaining and pioneering green practices in all aspects of our mission. KSC's SP recognizes that the best sustainable solutions use an interdisciplinary, collaborative approach spanning civil servant and contractor personnel from across the Center. This approach relies on the participation of all employees to develop and implement sustainability endeavors connected with the following ten goals: Reduce greenhouse gas (GHG) emissions. Design, build and maintain sustainable buildings, facilities and infrastructure. Leverage clean and renewable energy. Increase water conservation. Improve fleet and vehicle efficiency and management. Purchase sustainable products and services. Minimize waste and prevent pollution. Implement performance contracts for Federal buildings. Manage electronic equipment and data centers responsibly. Pursue climate change resilience. The KSC SP details the strategies and actions that address the following objectives: Reduce Center costs. center dot Increase energy and water efficiencies. Promote smart buying practices. Increase reuse and recycling while decreasing waste. Benefit the community. Meet or exceed the EO and NASA SSPP sustainability goals.

Sustainability↗
NASA NTRS2017

Isotopic Composition of Carbonates in Antarctic Ordinary Chondrites and Miller Range Nakhlites: Insights into Martian Amazonian Aqueous Alteration

The martian surface contains features of ancient fluvial systems. Stable isotope analysis of carbonates that form in aqueous systems can reveal their formation conditions. The Nakhlite meteorites originally formed on Mars 1.3 Ga and were later exposed to aqueous fluids that left behind carbonate minerals [1], thus analysis of these carbonates can provide data to understand Amazonian climate conditions on Mars. Carbonates found in the Nakhlite meteorites contain a range of delta(sup 13)C values, which may be either martian carbonates or terrestrial contamination. To better under-stand terrestrial weathering products and martian carbonate formation processes, we conducted a set of carbonate isotope analyses on Antarctic meteorites focusing on Miller Range (MIL) Nakhlites as well as Ordinary Chondrites (OCs) (Figure 1)[1-11] [12]. OCs of petrology type H, L, and LL 3-6 were selected since they are not expected to contain preterrestrial carbonates, yet they have visible evaporite minerals on the fusion crust indicating terrestrial alteration. These cryogenically formed terrestrial carbonates may also provide an analog for cryogenic carbonate formation on Mars.

Evans, M. E.↗
NASA NTRS2020

Unprecedented Atmospheric Conditions (1948–2019) Drive the 2019 Exceptional Melting Season Over the Greenland Ice Sheet

Understanding the role of atmospheric circulation anomalies on the surface mass balance of the Greenland ice sheet (GrIS) is fundamental for improving estimates of its current and future contributions to sea level rise. Here, we show, using a combination of remote sensing observations, regional climate model outputs, reanalysis data, and artificial neural networks, that unprecedented atmospheric conditions (1948–2019) occurring in the summer of 2019 over Greenland promoted new record or close-to-record values of surface mass balance (SMB), runoff, and snowfall. Specifically, runoff in 2019 ranked second within the 1948–2019 period (after 2012) and first in terms of surface mass balance negative anomaly for the hydrological year 1 September 2018–31 August 2019. The summer of 2019 was characterized by an exceptional persistence of anticyclonic conditions that, in conjunction with low albedo associated with reduced snowfall in summer, enhanced the melt–albedo feedback by promoting the absorption of solar radiation and favored advection of warm, moist air along the western portion of the ice sheet towards the north, where the surface melt has been the highest since 1948. The analysis of the frequency of daily 500 hPa geopotential heights obtained from artificial neural networks shows that the total number of days with the five most frequent atmospheric patterns that characterized the summer of 2019 was 5 standard deviations above the 1981–2010 mean, confirming the exceptional nature of the 2019 season over Greenland.

Greenland ice sheet↗