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At least 1,027 records · Page 57

Design of the UCLA general circulation model

An edited version is reported of notes distributed at the Summer Workshop on the UCLA General Circulation Model in June 1971. It presents the computational schemes of the UCLA model, along with the mathematical and physical principles on which these schemes are based. Included are the finite difference schemes for the governing fluid-dynamical equations, designed to maintain the important integral constraints and dispersion characteristics of the motion. Also given are the principles of parameterization of cumulus convection by an ensemble of identical clouds. A model of the ground hydrology, involving the liquid, ice and snow states of water, is included. A short summary is given of the scheme for computing solar and infrared radiation transfers through clear and cloudy air.

Arakawa, A.↗

Preparing an on-Demand Cloud Processing Workflow for NISAR Ecosystems Science Products

In preparation for the NISAR launch and data collection in 2024, the NISAR Project Science Team is building workflows for each Science Team discipline (Ecosystems, Cryosphere, and Solid Earth). This abstract focuses on the Ecosystem disciplines and the development of on-demand cloud-processing workflows for wetlands inundation, forest biomass, agricultural active crop area, and forest disturbance. The workflow simulates NISAR data using UAVSAR or ALOS-2 Single Look Complex data, which are processed to Level 2 geocoded polarimetric covariance matrix products using InSAR Scientific Computing Environment 3.0 software and to Level 3 science products using the Algorithm Theoretical Basis Documents. In this presentation, we describe these workflows and efforts to improve efficiency and data accessibility by using a cloud processing system. We present preliminary sample products from each Ecosystem discipline: inundation, forest biomass, crop area, and forest disturbance.

Christensen, Alexandra↗

A comparison of cloud motion winds from ATS 6 images with coinciding SMS 1 winds

A methodology is developed for accurate measurement of cloud motion winds from the geosynchronous ATS 6 image data. Attitude changes between consecutive images (as a function of scan-line number) are accounted for in wind computations through measurement of the earth-edge displacements between the successive infrared images. Also, an image matching procedure is used to remove obvious and distracting image distortions. The availability of SMS imagery coinciding with ATS 6 imagery makes SMS an excellent reference against which the quality of ATS 6 winds can be tested. The resulting winds inferred from cloud displacement measurements taken from a sequence of the corrected images are found to agree better than 2 m/sec rms with winds measured from coincident SMS 1 imagery.

Kuhlow, W. W.↗

Importance of Ice Nucleation and Precipitation on Climate With the Parameterization of Unified Microphysics Across Scales Version 1 (PUMASv1)

Cloud microphysics is critical for weather and climate prediction. In this work, we document updates and corrections to the cloud microphysical scheme used in the Community Earth System Model (CESM) and other models. These updates include a new nomenclature for the scheme, now called Parameterization of Unified Microphysics Across Scales (PUMAS), and the ability to run the scheme on graphics processing units (GPUs). The main science changes include refactoring an ice number limiter and associated changes to ice nucleation, adding vapor deposition onto snow, and introducing an implicit numerical treatment for sedimentation. We also detail the improvements in computational performance that can be achieved with GPU acceleration. We then show the impact of these scheme changes on the (a) mean state climate, (b) cloud feedback response to warming, and (c) aerosol forcing. We find that corrections are needed to the immersion freezing parameterization and that ice nucleation has important impacts on climate. We also find that the revised scheme produces less cloud liquid and ice but that this can be adjusted by changing the loss process for cloud liquid (autoconversion). Furthermore, there are few discernible effects of the PUMAS changes on cloud feedbacks but some reductions in the magnitude of aerosol–cloud interactions (ACIs). Small cloud feedback changes appear to be related to the implicit sedimentation scheme, with a number of factors affecting ACIs.

Clouds↗

Accelerating Control Systems with GitOps: A Path to Automation and Reliability

GitOps is a foundational approach for modernizing infrastructure by leveraging Git as the single source of truth for declarative configurations. The poster explores how GitOps transforms traditional control system infrastructure, services and applications by enabling fully automated, auditable, and version-controlled infrastructure management. Cloud-native and containerized environments are shifting the ecosystem not only in the IT industry but also within the computational science field, as is the case of CERN and Diamond Light Source among other Accelerator/Science facilities which are slowly shifting towards modern software and infrastructure paradigms. The ACORN project, which aims to modernize Fermilab’s control system infrastructure and software is implementing proven best-practices and cutting-edge technology standards including GitOps, containerization, infrastructure as code and modern data pipelines for control system data acquisition and the inclusion of AI/ML in our accelerator complex.

Gonzalez, M. [Fermilab]↗

Planetary geology, stellar evolution and galactic cosmology

Field studies of selected basalt flows in the Snake River Plain, Idaho, were made for comparative lunar and Mars geological investigations. Studies of basalt lava tubes were also initiated in Washington, Oregon, Hawaii, and northern California. The main effort in the stellar evolution research is toward the development of a computer code to calculate hydrodynamic flow coupled with radiative energy transport. Estimates of the rotation effects on a collapsing cloud indicate that the total angular momentum is the critical parameter. The study of Paschen and Balmer alpha lines of positronium atoms in the center of a galaxy is mentioned.

Source record↗

Stream network analysis from orbital and suborbital imagery, Colorado River Basin, Texas

The author has identified the following significant results. Orbital SL-2 imagery (earth terrain camera S-190B), received September 5, 1973, was subjected to quantitative network analysis and compared to 7.5 minute topographic mapping (scale: 1/24,000) and U.S.D.A. conventional black and white aerial photography (scale: 1/22,200). Results can only be considered suggestive because detail on the SL-2 imagery was badly obscured by heavy cloud cover. The upper Bee Creek basin was chosen for analysis because it appeared in a relatively cloud-free portion of the orbital imagery. Drainage maps were drawn from the three sources digitized into a computer-compatible format, and analyzed by the WATER system computer program. Even at its small scale (1/172,000) and with bad haze the orbital photo showed much drainage detail. The contour-like character of the Glen Rose Formation's resistant limestone units allowed channel definition. The errors in pattern recognition can be attributed to local areas of dense vegetation and to other areas of very high albedo caused by surficial exposure of caliche. The latter effect caused particular difficulty in the determination of drainage divides.

Baker, V. R.↗

Rain, fog, and clouds for aircraft simulators

Environmental chamber creates realistic fog and rain effects in aircraft simulator. It reproduces clouds, homogeneous fog, patches of fog, rain and fog, and rain only. It is used with real time digital computer, color computer generated image display that simulates airport lights, or color television camera that produces moving display of airport runway as depicted on model terrain board.

Chase, W. D.↗

Severe storms and local weather research

Developments in the use of space related techniques to understand storms and local weather are summarized. The observation of lightning, storm development, cloud development, mesoscale phenomena, and ageostrophic circulation are discussed. Data acquisition, analysis, and the development of improved sensor and computer systems capability are described. Signal processing and analysis and application of Doppler lidar data are discussed. Progress in numerous experiments is summarized.

Source record↗

Interactive processing of SEASAT scatterometer data

The Man-computer Interactive Data Access System (McIDAS), adapted for the interactive processing of satellite-derived temperature soundings and cloud-track winds for the FGGE Special Effort, was adapted for the processing and evaluation of SEASAT data. The implementation of the McIDAS SEASAT processing system required (1) extensive modifications to the data base structure to store and display SASS winds, as well as corroborative level II data, model first guess fields and level III analyses, and (2) the development of software to dealias and analyze SASS wind vectors interactively.

Atlas, R.↗

Ultraviolet spectroscopy of the planetary nebula in the Fornax galaxy

The planetary nebula in the Fornax dwarf spheroidal galaxy is carbon rich, according to calculations based on measurements of the 1909 A emission line doublet of semiforbidden C III obtained with the International Ultraviolet Explorer. The ratio N(C)/N(O) is approximately equal to 3.7, comparable to the largest reliably determined carbon/oxygen ratios in high excitation planetaries of the Milky Way. The present result is based on four low-dispersion spectra with a combined exposure time of 27.2 hours; the Fornax planetary nebula is probably the most distant known planetary that can be observed with IUE. The IUE data were analyzed together with visible-wavelength emission-line fluxes reported by Danziger et al. (1978) to compute abundances for various elements. In terms of chemical composition, the Fornax nebula resembles planetary nebulae in the Magellanic Clouds more closely than it does typical or carbon-rich planetaries in the Galaxy.

Maran, S. P.↗

Reduction of weather effects in the calculation of sea ice concentration from microwave radiances

A technique is presented which improves existing methods of calculating sea ice concentrations from microwave radiances by reducing weather-related effects over open ocean areas and in the vicinity of marginal sea ice zones. Winds, atmospheric water vapor, cloud liquid water, and rain increase the microwave emission over these regions and thus result in erroneous values of computed sea ice concentration. The method described is based on the microwave spectral properties of sea ice and ice-free ocean and utilizes ratios of the polarized radiances at the 0.81-cm (37 GHz) and 1.7-cm (18 GHz) wavelengths. Following a discussion of the physical basis for this technique, examples are provided which demonstrate its utility. While the technique was developed for use with the Nimbus 7 scanning multichannel microwave radiometer data, it is applicable also to data from other microwave radiometers operating in a similar wavelength range.

Gloersen, P.↗

Comparative accuracy of selected multiple scattering approximations

Doubling method computational results which have yielded plane albedo, total transmission and fractional absorption for plane-parallel atmospheres composed of cloud droplets are presently compared with data obtained with selected radiative transfer approximations. The relative and absolute accuracies of asymptotic theory for thick layers and delta-Eddington, Meador-Weaver (1980) and Coakley-Chylek (1975) approximations are compared as a function of optical thickness, solar zenith angle, and single scattering albedo. The delta-Eddington approximation is the most accurate for conservative scattering when the solar zenith angle is small, while Meador-Weaver is the most accurate for nonconservative scattering.

King, M. D.↗

Visible phase curves of Uranus and Neptune and scattering in their atmospheres

The Voyager 1 and Voyager 2 narrow angle cameras have been imaging Uranus and Neptune (through several filters) from distances of several AU for the past four years. The justification for this is to determine the way in which the albedoes of the two planets vary with angle from the sun. The Voyager 1 spacecraft has already reached a phase angle of approx. 40 deg. for Neptune and approx. 70 deg. for Uranus. The albedo of a gaseous planet depends on the phase angle (angle from the sun through the planet to the observer), the color being observed, and the vertical distribution and nature of aerosols and clouds in the atmosphere of the planet. Since the colors are known and the phase angles, and phase curves will be used to constrain models of the aerosol and cloud structrures of Uranus and Neptune. A knowledge of the way albedo varies with phase angle allows one to compute the total amount of sunlight being absorbed by a planet. With knowledge of the solar flux incident on the planet and knowledge of how much infrared is being emitted by the planet (at least in the direction of the Earth and sun) one can determine a rough extimate of the internal heat source of the planet. Although Jupiter and Saturn have measured internal heat sources of magnitude comparable to their absorbed energy from the sun, preliminary results indicate that Uranus may not have an internal heat and that Neptune if it has one that heat source is small.

Wenkert, D.↗

Implications of the BATSE data for a helocentric origin of gamma-ray bursts

Several possible models have been suggested to explain the observed distribution of gamma-ray bursts: heliocentric distributions such as the Oort cloud, large galactic halos, and cosmological models. We report here on an investigation into the implications of the Burst and Transient Source Experiment (BATSE) gamma-ray burst distribution (Meegan et al. 1992a) data on the possible helocentric origin of gamma-ray bursts. We find no statistically significant anisotropy in the angular distribution of the bursts in a Sun-referenced coordinate system; there is no dipole moment in the direction of the Sun, and no quardrupole moment associated with the ecliptic plane. We have employed direct analytic calculations and Monte Carlo simulations of sources in the Oort cloud to constrain possible helicentric burst distributions. These can produce distributions consistent with the observed angular isotropy, the meal value of V/V(sub max), and the observed C/C(sub min) distribution of BATSE, and provide limits to burst energy of a few times approximately 10(exp 27) ergs. However, the agreement of the heliocentric C/C(sub min) distributions with the BATSE data is attributable to the relatively limited sampling of strong, nearby bursts. These bursts are known from observation to be homogeneously distributed, yet the density of sources in the Oort cloud is not constant in this region. Integral number-intensity distributions from the Oort cloud for larger numbers of bursts cannot reproduce the known homogeneity of the strong bursts without modification to the computed cometary number density and are therefore unlikely explanations of the gamma-ray burst distribution.

Horack, J. M.↗

Atmospheric Solar Heating in Minor Absorption Bands

Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

Chou, Ming-Dah↗

Performance of an Optimized Eta Model Code on the Cray T3E and a Network of PCs

In the year 2001, NASA will launch the satellite TRIANA that will be the first Earth observing mission to provide a continuous, full disk view of the sunlit Earth. As a part of the HPCC Program at NASA GSFC, we have started a project whose objectives are to develop and implement a 3D cloud data assimilation system, by combining TRIANA measurements with model simulation, and to produce accurate statistics of global cloud coverage as an important element of the Earth's climate. For simulation of the atmosphere within this project we are using the NCEP/NOAA operational Eta model. In order to compare TRIANA and the Eta model data on approximately the same grid without significant downscaling, the Eta model will be integrated at a resolution of about 15 km. The integration domain (from -70 to +70 deg in latitude and 150 deg in longitude) will cover most of the sunlit Earth disc and will continuously rotate around the globe following TRIANA. The cloud data assimilation is supposed to run and produce 3D clouds on a near real-time basis. Such a numerical setup and integration design is very ambitious and computationally demanding. Thus, though the Eta model code has been very carefully developed and its computational efficiency has been systematically polished during the years of operational implementation at NCEP, the current MPI version may still have problems with memory and efficiency for the TRIANA simulations. Within this work, we optimize a parallel version of the Eta model code on a Cray T3E and a network of PCs (theHIVE) in order to improve its overall efficiency. Our optimization procedure consists of introducing dynamically allocated arrays to reduce the size of static memory, and optimizing on a single processor by splitting loops to limit the number of streams. All the presented results are derived using an integration domain centered at the equator, with a size of 60 x 60 deg, and with horizontal resolutions of 1/2 and 1/3 deg, respectively. In accompanying charts we report the elapsed time, the speedup and the Mflops as a function of the number of processors for the non-optimized version of the code on the T3E and theHIVE. The large amount of communication required for model integration explains its poor performance on theHIVE. Our initial implementation of the dynamic memory allocation has contributed to about 12% reduction of memory but has introduced a 3% overhead in computing time. This overhead was removed by performing loop splitting in some of the high demanding subroutines. When the Eta code is fully optimized in order to meet the memory requirement for TRIANA simulations, a non-negligeable overhead may appear that may seriously affect the efficiency of the code. To alleviate this problem, we are considering implementation of a new algorithm for the horizontal advection that is computationally less expensive, and also a new approach for marching in time.

Kouatchou, Jules↗

Models for the Infrared Cavity of HH 46/47

We have modeled the limb-brightened cavity seen in the new Spitzer Space Telescope IR images of the southwest lobe of HH 46/47 as the bow shock driven by an outflow from a young, low-mass star. We present models in which the outflow is a perfectly collimated, straight jet, models in which the jet precesses, and finally a model in which the outflow takes the form of a latitude-dependent wind. We study cases in which the outflow moves into a constant-density cloud and into a stratified cloud. We find that the best agreement with the observed cavity is obtained for the precessing jet in a stratified cloud. However, the straight jet (traveling in a stratified cloud) also gives cavity shapes close to the observed one. The latitude-dependent wind model that we have computed gives cavity shapes that are substantially wider than the observed cavity. We therefore conclude that the cavity seen in the Spitzer observations of the southwest lobe of the HH 46/47 outflow do not seem to imply the presence of a latitude-dependent wind, as it can be modeled successfully with a perfectly collimated jet model.

Herbig Haro objects↗