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At least 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Combined Radar and Radiometer Analysis of Precipitation Profiles for a Parametric Retrieval Algorithm

A methodology to analyze precipitation profiles using the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and precipitation radar (PR) is proposed. Rainfall profiles are retrieved from PR measurements, defined as the best-fit solution selected from precalculated profiles by cloud-resolving models (CRMs), under explicitly defined assumptions of drop size distribution (DSD) and ice hydrometeor models. The PR path-integrated attenuation (PIA), where available, is further used to adjust DSD in a manner that is similar to the PR operational algorithm. Combined with the TMI-retrieved nonraining geophysical parameters, the three-dimensional structure of the geophysical parameters is obtained across the satellite-observed domains. Microwave brightness temperatures are then computed for a comparison with TMI observations to examine if the radar-retrieved rainfall is consistent in the radiometric measurement space. The inconsistency in microwave brightness temperatures is reduced by iterating the retrieval procedure with updated assumptions of the DSD and ice-density models. The proposed methodology is expected to refine the a priori rain profile database and error models for use by parametric passive microwave algorithms, aimed at the Global Precipitation Measurement (GPM) mission, as well as a future TRMM algorithms.

Masunaga, Hirohiko↗
NASA NTRS2007

Overview of TRMM Data Products and Services

November 27, 2007 marks the l0th anniversary of the launch of the Tropical Rainfall Measuring Mission (TRMM) satellite. In anticipation of this anniversary, this paper will present an overview of the various TRMM data products currently available including the standard products, near real-time products, special products, and prototype products. It also will present an easy way to obtain these data. TRMM standard products have been publicly available since a few months after launch in November 1997. TRMM is currently on version 6 of the data product. Version 3 was the "at launch" version. The approval for each of these versions came through the Joint TRMM Science Team. Standard products are divided into 3 categories: single TRMM instrument, Visible Infrared Scanner (VIRS), TRMM Microwave Imager (TMI), and Precipitation Radar (PR); combined TRMM products (PR and TMI); finally TRMM and other satellites (combined, TMI, SSMI, AMSRE, AMSU). The single TRMM instrument products are processed through 4 levels: Level lA, science data packets processed into orbital files; Level 1B and lC, geolocated data at the instrument field of view; Level 2, geolocated, geophysical parameters at the instrument field of view; Level 3, time aggregated, gridded geophysical parameters. These products are available with 24 hours of production through an anonymous ftp account on trmmopen.gsfc.nasa.gov. The TRMM data system started to produce near real-time products at the end of 1999. They are currently available only through a controlled user account. However, approval to get access to this account can be obtained by sending a note to Erich.F.Stoclter@nasa.gov providing the reason for access and contact information including a valid email. TRMM is not restricting access but needs the information to determine the usefulness of near-real time data to the general science community including applications agencies. TRMM near real-time products are swath products up to Level 2 of processing. The oldest data in the swath is generally no older than 120 minutes when it becomes available to the community. The real-time products including a VIRS level lB, a TMI parameter reduced 1B, a TMI level 2 parameter reduced rain product, a PR level 2 surface rain product, and a PR level 2 rain product with 25 vertical levels. Currently, TRMM also produces a gridded 3 hour global merged product from several radiometers including AMSU and from radiometercalibrated IR data. The paper also describes several simple-format gridded text products available fiom the trmmopen.gsfc.nasa.gov anonymous fip server denoted as 3668 products. These products were produced to provide rain estimates from the three TRMM instruments in a universal format (ASCII) that requires very little data format knowledge. The paper goes on to describe prototype L1 radiometer products that apply an early intercalibration approach that provides a starting point to be used for Global Precipitation Measurement mission radiometer products. The paper also provides a brief overview of a precipitation features data product being produced using TRMM products including the Lighting Imaging Sensor (LIS) using an algorithm developed at the University of Utah and distributed by that organization. The paper concludes with some possible changes to products that are planned for the next reprocessing cycle and special services such as geographical subsetting available to the science community.

Stocker, Erich Franz↗
NASA NTRS2008

Availability of High Quality TRMM Ground Validation Data from Kwajalein, RMI: A Practical Application of the Relative Calibration Adjustment Technique

Since the Tropical Rainfall Measuring Mission (TRMM) satellite launch in November 1997, the TRMM Satellite Validation Office (TSVO) at NASA Goddard Space Flight Center (GSFC) has been performing quality control and estimating rainfall from the KPOL S-band radar at Kwajalein, Republic of the Marshall Islands. Over this period, KPOL has incurred many episodes of calibration and antenna pointing angle uncertainty. To address these issues, the TSVO has applied the Relative Calibration Adjustment (RCA) technique to eight years of KPOL radar data to produce Ground Validation (GV) Version 7 products. This application has significantly improved stability in KPOL reflectivity distributions needed for Probability Matching Method (PMM) rain rate estimation and for comparisons to the TRMM Precipitation Radar (PR). In years with significant calibration and angle corrections, the statistical improvement in PMM distributions is dramatic. The intent of this paper is to show improved stability in corrected KPOL reflectivity distributions by using the PR as a stable reference. Inter-month fluctuations in mean reflectivity differences between the PR and corrected KPOL are on the order of 1-2 dB, and inter-year mean reflectivity differences fluctuate by approximately 1 dB. This represents a marked improvement in stability with confidence comparable to the established calibration and uncertainty boundaries of the PR. The practical application of the RCA method has salvaged eight years of radar data that would have otherwise been unusable, and has made possible a high-quality database of tropical ocean-based reflectivity measurements and precipitation estimates for the research community.

Marks, David A.↗
NASA NTRS2007

Comparisons of Instantaneous TRMM Ground Validation and Satellite Rain Rate Estimates at Different Spatial Scales

This study provides a comprehensive inter-comparison of instantaneous rain rates observed by the two rain sensors aboard the TRMM satellite with ground data from two regional sites established for long-term ground validation: Kwajalein Atoll and Melbourne, Florida. The satellite rain algorithms utilize remote observations of precipitation collected by the TRMM microwave imager (TMI) and the Precipitation Radar (PR) aboard the TRMM satellite. Three standard Level I1 rain products are generated from operational applications of the TMI, PR and Combined (COM) rain algorithms using rain information collected from the TMI and the PR along the orbital track of the TRMM satellite. In the first part of the study, 0.25 x 0.25 instantaneous rain rates obtained from the TRMM 3668 product were analyzed and compared to instantaneous GV rain rates gridded at a scale of 0.5deg x 0.5. In the second part of the study, TMI, PR, COM and GV rain rates were spatio-temporally matched and averaged at the scale of TMI footprint (- 150 sq km). This study covered a six-year period 1999-2004 and consisted of over 50,000 footprints for each GV site. In the first analysis our results showed that all of the respective rain rate estimates agree well, with some exceptions. The more salient differences were associated with heavy rain events in which one or more of the algorithms failed to properly retrieve these extreme events. Also, it appears that there is a preferred mode of precipitation for TMI rain rates at or near 2 mm/hr over the ocean. This mode was noted over ocean areas of Kwajalein and Melbourne and has been observed in TRMM tropical-global ocean areas as well.

Wolff, David B.↗
NASA NTRS2008

Current Scientific Progress and Future Scientific Prospects Enabled by Spaceborne Precipitation Radar Measurements

First, we examine current scientific progress and understanding that have been possible through use of spaceborne precipitation radar measurements being provided by the TRMM and CloudSat satellites. Second, we look across a future 20-year time frame to assess how and why anticipated improvements in space radar systems will further advance scientific progress into topic areas once considered beyond the realm of space-based remote sensing. JAXA's 13.8 GHz Ku-band cross-track scanning Precipitation Radar (PR) developed for flight on NASA's non-sun-synchronous, diurnally-precessing TRMM satellite, was the first Earth radar flown in space that was designed specifically for precipitation measurement. Its proven accuracy in measuring global rainfall in the tropics and sub-tropics and its unanticipated longevity in continuing these measurements beyond a full decade have established the standards against which all follow-up and future space radars will be evaluated. In regards to the current PR measurement time series, we will discuss a selection of major scientific discoveries and impacts which have set the stage for future radar measuring systems. In fact, the 2nd contemporary space radar applicable for terrestrial precipitation measurement, i.e., JPL-CSA's 94 GHz nadir-staring Cloud Profiling Radar (CPR) flown on NASA's sun-synchronous CloudSat satellite, although designed primarily for measurement of non-precipitating cloud hydrometeors and aerosols, has also unquestionably advanced precipitation measurement because CPR's higher frequency and greatly increased sensitivity (approximately 30 dBZ) has enabled global observations of light rain rate spectrum processes (i.e., rain rates below 0.05 mm per hourand of precipitation processes in the high troposphere (particularly ice phase processes). These processes are beyond reach of the TRMM radar because the PR sensitivity limit is approximately 17 dBZ which means its lower rain rate cutoff is around 0.3 mm per hour and its vertical profiling acuity is greatly limited above the melting layer. Thus, the newer CPR measurements have become important for a variety of scientific reasons that will be highlighted and assessed. In considering scientific progress likely to stem from future precipitation radar systems, we will specifically examine possible scientific impacts from three anticipated missions for which NASA and various of its space agency partners are expected to lead the way. These three missions are: (1) the nearterm Global Precipitation Measuring (GPM) Mission; (2) the decadal timeline Aerosol and Cloud Experiment (ACE) Mission; and the post-decadal timeline NEXRAD in Space (NIS) Mission. The observational capabilities of the planned radar systems for each of these three satellite missions are distinct from each other and each provides progressive improvements in precipitation measuring and scientific research capabilities relative to where we are now -- insofar as TRMM PR and the CloudSat CPR capabilities. The potential innovations in scientific research will be discussed in a framework of likely synergisms between next-generation radar capabilities and accessible dynamical and microphysical properties that have heretofore evaded detection.

Smith, Eric A.↗
NASA NTRS2010

Titanium Mass-balance Analysis of Paso Robles Soils: Elemental Gains and Losses as Affected by Acid Alteration Fluids

The Columbia Hills soils have been exposed to aqueous alteration in alkaline [1] as well as acid conditions [2,3]. The Paso Robles class soils are bright soils that possess the highest S concentration of any soil measured on Mars [2]. Ferric-sulfate detection by Moessbauer analysis indicated that acid solutions were involved in forming these soils [4]. These soils are proposed to have formed by alteration of nearby rock by volcanic hydrothermal or fumarolic activity. The Paso Robles soils consist of the original Paso Robles-disturbed-Pasadena (PR-dist), Paso Robles- PasoLight (PR-PL), Arad-Samra, Arad-Hula, Tyrone- Berker Island1 and Tyrone-MountDarwin [2 ,3. ]Chemical characteristics indicate that the PR-dist and PR-PL soils could be derived from acid weathering of local Wishstone rocks while the Samra and Hula soils are likely derived from local Algonquin-Iroquet rock [3]. The Paso Robles soils were exposed to acidic sulfur bearing fluids; however, little else is known about the chemistry of the alteration fluid and its effects on the alteration of the proposed parent materials. The objectives of this work are to conduct titanium normalized mass-balance analysis to1) assess elemental gains and losses from the parent materials in the formation of the Paso Robles soils and 2) utilize this information to indicate the chemical nature of the alteration fluids.

Sutter, Brad↗
DOE OSTI2023

MSR Proliferation Resistance and Physical Protection White Paper

This document represents the status of Proliferation Resistance and Physical Protection (PR&PP) characteristics for the Molten Salt Reactor designs selected by the Generation IV International Forum (GIF) Molten Salt Reactor (MSR) provisional System Steering Committee (pSSC) as representatives of three broad classes of MSRs. The three classes of MSRs are: (1) Liquid-fueled with integrated salt processing, (2) Liquid-fueled without integrated salt processing, (3) Solid-fueled with salt coolant. The intent is to generate preliminary information about the PR&PP merits of the MSR Reactor Technology and to provide insights for optimizing their PR&PP performance for the benefit of MSR system designers. It updates the MSR analysis published in the 2011 report “Proliferation Resistance and Physical Protection of the Six Generation IV Nuclear Energy Systems”, prepared Jointly by the Proliferation Resistance and Physical Protection Working Group (PRPPWG) and the System Steering Committees of the Generation IV International Forum, taking into account the evolution of both the systems and the GIF R&D activities since its publication. The document, prepared jointly by the GIF PRPPWG and the GIF MSR pSSC, follows the high-level paradigm of the GIF Proliferation Resistance and Physical Protection Evaluation Methodology to investigate the Proliferation Resistance and Physical Protection features of the GIF MSR representative designs. For PR, the document analyses and discusses the proliferation resistance aspects in terms of robustness against State-based threats associated with diversion of materials, misuse of facilities, breakout scenarios, and production in clandestine facilities. Similarly, for physical protection, the document discusses the robustness against theft of material and sabotage by non-State actors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Materials Data on Pr3GaC by Materials Project

Pr3GaC is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional and consists of one methane molecule and one Pr3Ga framework. In the Pr3Ga framework, Pr is bonded in a linear geometry to two equivalent Ga atoms. Both Pr–Ga bond lengths are 2.77 Å. Ga is bonded to six equivalent Pr atoms to form corner-sharing GaPr6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrRh3C by Materials Project

PrRh3C is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pr is bonded to twelve equivalent Rh atoms to form PrRh12 cuboctahedra that share corners with twelve equivalent PrRh12 cuboctahedra, faces with six equivalent PrRh12 cuboctahedra, and faces with eight equivalent CRh6 octahedra. All Pr–Rh bond lengths are 3.01 Å. Rh is bonded to four equivalent Pr and two equivalent C atoms to form a mixture of distorted face, edge, and corner-sharing RhPr4C2 octahedra. The corner-sharing octahedra tilt angles range from 0–60°. Both Rh–C bond lengths are 2.13 Å. C is bonded to six equivalent Rh atoms to form CRh6 octahedra that share corners with six equivalent CRh6 octahedra and faces with eight equivalent PrRh12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrAl by Materials Project

PrAl is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pr is bonded in a body-centered cubic geometry to eight equivalent Al atoms. All Pr–Al bond lengths are 3.25 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrAu by Materials Project

PrAu is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pr is bonded in a body-centered cubic geometry to eight equivalent Au atoms. All Pr–Au bond lengths are 3.25 Å. Au is bonded in a body-centered cubic geometry to eight equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrO by Materials Project

PrO is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pr is bonded to six equivalent O atoms to form a mixture of corner and edge-sharing PrO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pr–O bond lengths are 2.55 Å. O is bonded to six equivalent Pr atoms to form a mixture of corner and edge-sharing OPr6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrGa by Materials Project

PrGa crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Pr is bonded in a 7-coordinate geometry to seven equivalent Ga atoms. There are a spread of Pr–Ga bond distances ranging from 3.19–3.31 Å. Ga is bonded in a 9-coordinate geometry to seven equivalent Pr and two equivalent Ga atoms. Both Ga–Ga bond lengths are 2.64 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrHg by Materials Project

PrHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Pr is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Pr–Hg bond lengths are 3.35 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrGe2 by Materials Project

PrGe2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Pr is bonded to twelve equivalent Ge atoms to form a mixture of edge and face-sharing PrGe12 cuboctahedra. There are eight shorter (3.24 Å) and four longer (3.47 Å) Pr–Ge bond lengths. Ge is bonded in a 9-coordinate geometry to six equivalent Pr and three equivalent Ge atoms. There are two shorter (2.56 Å) and one longer (2.60 Å) Ge–Ge bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrNi by Materials Project

PrNi crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Pr is bonded in a 7-coordinate geometry to seven equivalent Ni atoms. There are a spread of Pr–Ni bond distances ranging from 2.95–3.12 Å. Ni is bonded in a 9-coordinate geometry to seven equivalent Pr and two equivalent Ni atoms. Both Ni–Ni bond lengths are 2.65 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2AlCo2 by Materials Project

Pr2Co2Al crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to six equivalent Co atoms. There are four shorter (2.98 Å) and two longer (3.10 Å) Pr–Co bond lengths. Co is bonded in a 2-coordinate geometry to six equivalent Pr, one Co, and two equivalent Al atoms. The Co–Co bond length is 2.59 Å. Both Co–Al bond lengths are 2.52 Å. Al is bonded in a 12-coordinate geometry to four equivalent Co atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr2AlCo2 by Materials Project

Pr2Co2Al crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Pr is bonded in a 6-coordinate geometry to six equivalent Co atoms. There are a spread of Pr–Co bond distances ranging from 2.95–3.05 Å. Co is bonded in a 9-coordinate geometry to six equivalent Pr, one Co, and two equivalent Al atoms. The Co–Co bond length is 2.42 Å. There are one shorter (2.57 Å) and one longer (2.58 Å) Co–Al bond lengths. Al is bonded in a 12-coordinate geometry to four equivalent Co atoms.

36 MATERIALS SCIENCE↗