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Quarterly VAP Report - January to March

Description: The purpose of this report is to provide a concise status update for value-added products (VAP) implemented by the Atmospheric Radiation Measurement Climate Research Facility. The report is divided into the following sections: (1) new VAPs for which development has begun, (2) progress on existing VAPs, (3) future VAPs that have been recently approved, (4) other work that leads to a VAP, and (5) top requested VAPs from the archive. New information is highlighted in blue text. New information about processed data by the developer is highlighted in red text. The upcoming milestones and dates are highlighted in green.
Date: June 7, 2012
Creator: Sivaraman, C
Partner: UNT Libraries Government Documents Department

ARAC simulations of the ash plume from the December 1997 eruption of Soufriere Hills Volcano, Montserrat

Description: Ash clouds generated by erupting volcanoes represent a serious hazard to military and civil aviation. The dispersion modeling system of the Atmospheric Release Advisory Capability (ARAC) has been used to model the cloud resulting from the eruption of the Soufriere Hills volcano, Montserrat in December 1997. A clone of parts of the ARAC system, now being installed at the Air Force Weather Agency (AFWA), will enable AFWA to provide hazard guidance to military operations in the vicinity of erupting volcanoes. This paper presents ARAC� s modeling results and discusses potential application of similar calculations for AFWA support during future events.
Date: October 1, 1998
Creator: Ellis, J. S.; Lefevre, R. J.; Pace, J. C.; Vogt, P. J. & Voight, B.
Partner: UNT Libraries Government Documents Department

Dynamics of Arctic and Sub-Arctic Climate and Atmospheric Circulation: Diagnosis of Mechanisms and Biases Using Data Assimilation

Description: The overall goal of work performed under this grant is to enhance understanding of simulations of present-day climate and greenhouse gas-induced climate change. The examination of present-day climate also includes diagnostic intercomparison of model simulations and observed mean climate and climate variability using reanalysis and satellite datasets. Enhanced understanding is desirable 1) as a prerequisite for improving simulations; 2) for assessing the credibility of model simulations and their usefulness as tools for decision support; and 3) as a means to identify robust behaviors which commonly occur over a wide range of models, and may yield insights regarding the dominant physical mechanisms which determine mean climate and produce climate change. A further objective is to investigate the use of data assimilation as a means for examining and correcting model biases. Our primary focus is on the Arctic, but the scope of the work was expanded to include the global climate system.
Date: February 17, 2010
Creator: DeWeaver, Eric T.
Partner: UNT Libraries Government Documents Department

Relationship Between Atmospheric circulation and Snowpack in theWestern United States

Description: Snow anomalies in the western United States (U.S.) have beenwidely investigated by many researchers due to its impact on wateravailability. This study focuses on how anomalous atmospheric circulationaffects snowpack accumulation in the western U.S. using observations andoutput from the National Center for Atmospheric Research (NCAR) CommunityClimate Model version 3 (CCM3). Our results indicate that themid-latitude atmospheric circulation anomalies induced by the ElNino-Southern Oscillation (ENSO) tend to drive winter precipitationshifts, leading to an anomalous snowpack distribution in the western U.S.The warm phase of ENSO produces increased snowpack in the Southwest,while the cold phase of ENSO generates increased snowpack in theNorthwest. Temperature has a secondary impact on the anomalous snowpackdistribution during ENSO episodes. Additionally, the non-linearatmospheric dynamics-related Pacific-North American (PNA) pattern isfound to strongly affect snow anomalies in the western U.S. independentfrom ENSO. The positive phase of the PNA pattern produces coldertemperature and stronger precipitation due to the lower pressure in theregion, leading to an above normal snowpack. Conversely, the negativephase of the PNA pattern generates warmer temperature and weakerprecipitation resulting from the higher pressure, producing a below thannormal snowpack in the western U.S. In general, the NCAR-CCM3 reproducesthe observed processes. However, model biases are identified andreported. The information provided in this study strengthens ourunderstanding of climate and water supply variability in the westernU.S.
Date: June 2, 2004
Creator: Jin, Jiming; Miller, Norman L.; Sorooshian, Soroosh & Gao, Xiaogang
Partner: UNT Libraries Government Documents Department

Identification of external influences on temperatures in California

Description: We use eight different observational datasets to estimate California-average temperature trends over 1950-1999. Observed results are compared to trends from a suite of control simulations of natural internal climate variability. Observed increases in annual-mean surface temperature are distinguishable from climate noise in some but not all observational datasets. The most robust results are large positive trends in mean and maximum daily temperatures in late winter/early spring, as well as increases in minimum daily temperatures from January to September. These trends are inconsistent with model-based estimates of natural internal climate variability, and thus require one or more external forcing agents to be explained. Our results suggest that the warming of Californian winters over the second half of the twentieth century is associated with human-induced changes in large-scale atmospheric circulation. We also hypothesize that the lack of a detectable increase in summertime maximum temperature arises from a cooling associated with large-scale irrigation. This cooling may have, until now, counteracted the warming induced by increasing greenhouse gases and urbanization effects.
Date: June 1, 2006
Creator: Bonfils, C; Duffy, P; Santer, B; Wigley, T; Lobell, D; Phillips, T et al.
Partner: UNT Libraries Government Documents Department

Final Technical Report ARM DOE Grant #DE-FG02-03ER63520 Parameterizations of Shortwave Radiactive Properties of Broken Clouds from Satellite and Ground-Based Measurements

Description: This study used DOE ARM data and facilities to: 1) study macroscopic properties of continental stratus clouds at SGP and the factors controlling these properties, 2) develop a scientific basis for understanding the pocesses responsible for the formation of boundary layer clouds using ARM observations in conjunction with simple parametric models and LES, and 3) evaluate cumulus cloud characteristics retrieved retrieved from the MMCR operating at TWP-Nauru. In addition we have used high resolution 94 GHz observations of boundary layer clouds and precipitation to: 1)develop techniques for using high temporal resolution Doppler velocities to study large-eddy circulations and turbulence in boundary layer clouds and estimate the limitations of using current and past MMCR data for boundary layer cloud studies, 2) evaluate the capability and limitation of the current MMCR data for estimating reflectivity, vertical velocities, and spectral under low-signal-to-noise conditions associated with weak non-precipitating clouds, 3) develop possible sampling modes for the new MMCR processors to allow for adequate sampling of boundary layer clouds, and 4) retrieve updraft and downdraft structures under precipitating conditions.
Date: June 19, 2006
Creator: Albrecht, Bruce, A.
Partner: UNT Libraries Government Documents Department

Development of NEXRAD Wind Retrievals as Input to Atmospheric Dispersion Models

Description: The objective of this study is to determine the feasibility that routinely collected data from the Doppler radars can appropriately be used in Atmospheric Dispersion Models (ADMs) for emergency response. We have evaluated the computational efficiency and accuracy of two variational mathematical techniques that derive the u- and v-components of the wind from radial velocities obtained from Doppler radars. A review of the scientific literature indicated that the techniques employ significantly different approaches in applying the variational techniques: 2-D Variational (2DVar), developed by NOAA¹s (National Oceanic and Atmospheric Administration's) National Severe Storms Laboratory (NSSL) and Variational Doppler Radar Analysis System (VDRAS), developed by the National Center for Atmospheric Research (NCAR). We designed a series of numerical experiments in which both models employed the same horizontal domain and resolution encompassing Oklahoma City for a two-week period during the summer of 2003 so that the computed wind retrievals could be fairly compared. Both models ran faster than real-time on a typical single dual-processor computer, indicating that they could be used to generate wind retrievals in near real-time. 2DVar executed ~2.5 times faster than VDRAS because of its simpler approach.
Date: March 6, 2007
Creator: Fast, Jerome D.; Newsom, Rob K.; Allwine, K Jerry; Xu, Qin; Zhang, Pengfei; Copeland, Jeffrey H. et al.
Partner: UNT Libraries Government Documents Department

Measurement and Improved Understanding of Vertical Transport and the Evaluation of these Processes in Mesoscale Models

Description: The NCAR effort is primarily focused on the analysis of a diverse suite of measurements taken at the southern end of the Salt Lake City Valley within the Jordan Narrows. These measurements include wind profiler, surface, lidar, radiosonde, multi-layered tether-sonde and sodar measurements. We are also collaborating with other VTMX investigators through linking our measurements within the Jordan Narrows with their investigations. The instrumentation was provided to interested VTMX investigators and was used extensively. Thus the NCAR data set played a large role in the results of the overall experiment. Our work under this proposal includes analysis of the observations, mesoscale modeling efforts in support of our VTMX analysis and general instrumentation development aimed at improving the measurement of vertical transport and mixing under stable conditions. This report is subdivided by research objectives.
Date: February 13, 2007
Creator: Parsons, David; Pinto, James; Brown, William; Cohn, Stephen & Morley, Bruce
Partner: UNT Libraries Government Documents Department

A Vertical Grid Module for Baroclinic Models of the Atmosphere

Description: The vertical grid of an atmospheric model assigns dynamic and thermo- dynamic variables to grid locations. The vertical coordinate is typically not height but one of a class of meteorological variables that vary with atmo- spheric conditions. The grid system is chosen to further numerical approx- imations of the boundary conditions so that the system is terrain following at the surface. Lagrangian vertical coordinates are useful in reducing the numerical errors from advection processes. That the choices will effect the numercial properties and accuracy is explored in this report. A MATLAB class for Lorentz vertical grids is described and applied to the vertical struc- ture equation and baroclinic atmospheric circulation. A generalized meteo- rolgoical coordinate system is developed which can support σ, isentropic θ vertical coordinate, or Lagrangian vertical coordinates. The vertical atmo- spheric column is a MATLAB class that includes the kinematic and ther- modynamic variables along with methods for computing geopoentials and terms relevant to a 3D baroclinc atmospheric model.
Date: April 1, 2008
Creator: Drake, John B.
Partner: UNT Libraries Government Documents Department

ASCOT 91 field experiment : PNL airsonde data summary.

Description: Pacific Northwest Laboratory (PNL) participated in the Winter 1991 Atmospheric Studies in Complex Terrain (ASCOT) field experiment conducted in the vicinity of the Rocky Flats Plant between Boulder and Denver, Colorado. This report contains a summary of operations and data associated with free-release-ball oon-borne atmospheric soundings made by PNL between January 29 and February 8, 1991. Given here are descriptions of the site and instrumentation, a brief summary of the soundings, and a description of the data post processing. The appendices contain a detailed summary of all soundings and ASCOT plots of completed soundings.
Date: July 1, 1991
Creator: Allwine, JM Hubbe and KJ
Partner: UNT Libraries Government Documents Department

ENSO Simulation in CGCMs and the Associated Errors in Atmospheric Response

Description: Tropical Pacific variability, and specifically the simulation of ENSO in coupled ocean-atmosphere general circulation models (CGCMs) has previously been assessed in many studies (McCreary and Anderson [1991], Neelin et al. [1992], Mechoso et al. [1995], Latif et al. [2000], and Davey et al. [2000]). These studies have concentrated on SST variations in the tropical Pacific, and discussions of the atmospheric response have been limited to east-west movements of the convergence zone. In this paper we discuss the large-scale atmospheric response to simulated ENSO events. Control simulations from 17 global CGCMs from CMIP (Meehl et al. [2000]) are studied. The web site http:// www-pcmdi.llnl.gov/cmip/modeldoc provides documentation of the configurations of the models.
Date: September 11, 2000
Creator: AchutaRao, K. & Sperber, K.R.
Partner: UNT Libraries Government Documents Department

Modeling of clouds and radiation for developing parameterizations of clouds in general circulation models

Description: We conducted modeling work in radiative transfer and cloud microphysics. Our work in radiative transfer included performance tests to other high accuracy methods and to measurements under cloudy, partial cloudy and cloud-free conditions. Our modeling efforts have been aimed to (1) develop an accurate and rapid radiative transfer model; (2) develop three-dimensional radiative transfer models; and (3) develop microphysics resolving cloud and aerosol models. We applied our models to investigate solar clear-sky model biases, investigate aerosol direct effects, investigate aerosol indirect effects, investigate microphysical properties of cirrus, investigate microphysical properties of stratus, investigate relationships between cloud properties, and investigate the effects of cloud structure.
Date: December 31, 1996
Creator: Toon, O.B.
Partner: UNT Libraries Government Documents Department

Intercomparison of the seasonal cycle in 200 hPa kinetic energy in AMIP GCM simulations

Description: The 200 hPa kinetic energy is represented by means of the spherical harmonic components for the Atmospheric Model Intercomparison Project (AMIP) simulations, the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis and the European Centre for Medium Range Weather Forecast Reanalysis (ERA). The data used are the monthly mean wind fields from 1979 to 1988. The kinetic energy is decomposed into the divergent (DKE) and rotational (RKE) components and emphasis is placed on examining the former. The two reanalysis data sets show reasonable agreement that is best for the rotational kinetic energy. The largest difference in the divergent kinetic energy occurs during the northern summer. As might be expected, the two analyses are closet in regions where there are sufficient observations such that the effect of the model used in the assimilation cycle are minimized. The observed RKE show only a slight seasonal cycle with a maximum occuring during the northern winter. The DKE, on the other hand, has a very pronounced seasonal cycle with maxima at the solsticial seasons and minima during the equinoctial seasons. The model results show a very large spread in the magnitudes of the RKE and DKE although the models all evince a seasonal variation in phase with that observed. The median values of the seasonal cycle of RKE and DKE for the models are usually superior to those of any individual model. Results are also presented for simulation following the AMIP protocol but using updated versions of the original AMIP entries. In most cases these new integrations show better agreement with the observations.
Date: October 1, 1996
Creator: Boyle, J.S.
Partner: UNT Libraries Government Documents Department

ARM single column model (SCM) intercomparison, procedures for case 1: summer 1995 SCM IOP

Description: The Atmospheric Radiation Measurement (ARM) Program is a multi- laboratory, interagency program that was created in 1989 with funding from the U.S. Department of Energy (DOE). The ARM Program is part of DOE`s effort to resolve scientific uncertainties about global climate change with a specific focus on improving the performance of general circulation models (GCMS) used for climate research and prediction. These improved models will help scientists better understand the influences of human activities on the earth`s climate. The objectives of the ARM Program are: (1) to relate observed atmospheric radiation to the temperature and composition of the atmosphere, especially water vapor and clouds, across a wide range of climatologically relevant possibilities, and (2) to develop and test improved parameterizations of radiation and radiative interactions with water vapor, aerosols, and clouds, for use in GCMS.
Date: April 1998
Creator: Cederwall, R. T. & Krueger, S. K.
Partner: UNT Libraries Government Documents Department

Volcanic loading: The dust veil index

Description: Dust ejected into the high atmosphere during explosive volcanic eruptions has been considered as a possible cause for climatic change. Dust veils created by volcanic eruptions can reduce the amount of light reaching the Earth`s surface and can cause reductions in surface temperatures. These climatic effects can be seen for several years following some eruptions and the magnitude and duration of the effects depend largely on the density or amount of tephra (i.e. dust) ejected, the latitude of injection, and atmospheric circulation patterns. Lamb (1970) formulated the Dust Veil Index (DVI) in an attempt to quantify the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact of a particular volcanic eruptions release of dust and aerosols over the years following the event. The DVI for any volcanic eruptions are available and have been used in estimating Lamb`s dust veil indices.
Date: September 1, 1985
Creator: Lamb, H.H.
Partner: UNT Libraries Government Documents Department

Anisotropic multi-resolution analysis in 2D, application to long-range correlations in cloud mm-radar fields

Description: Because of Earth`s gravitational field, its atmosphere is strongly anisotropic with respect to the vertical; the effect of the Earth`s rotation on synoptic wind patterns also causes a more subtle form of anisotropy in the horizontal plane. The authors survey various approaches to statistically robust anisotropy from a wavelet perspective and present a new one adapted to strongly non-isotropic fields that are sampled on a rectangular grid with a large aspect ratio. This novel technique uses an anisotropic version of Multi-Resolution Analysis (MRA) in image analysis; the authors form a tensor product of the standard dyadic Haar basis, where the dividing ratio is {lambda}{sub z} = 2, and a nonstandard triadic counterpart, where the dividing ratio is {lambda}{sub x} = 3. The natural support of the field is therefore 2{sup n} pixels (vertically) by 3{sup n} pixels (horizontally) where n is the number of levels in the MRA. The natural triadic basis includes the French top-hat wavelet which resonates with bumps in the field whereas the Haar wavelet responds to ramps or steps. The complete 2D basis has one scaling function and five wavelets. The resulting anisotropic MRA is designed for application to the liquid water content (LWC) field in boundary-layer clouds, as the prevailing wind advects them by a vertically pointing mm-radar system. Spatial correlations are notoriously long-range in cloud structure and the authors use the wavelet coefficients from the new MRA to characterize these correlations in a multifractal analysis scheme. In the present study, the MRA is used (in synthesis mode) to generate fields that mimic cloud structure quite realistically although only a few parameters are used to control the randomness of the LWC`s wavelet coefficients.
Date: March 1, 1999
Creator: Davis, A.B. & Clothiaux, E.
Partner: UNT Libraries Government Documents Department

Sea breeze regimes in the New York City region - modeling and radar observations

Description: During spring and summer, the well known sea breeze circulations can strongly influence airport operations, air-quality, energy utilization, marine activities and infrastructure. The geographic configuration of the New York City region presents a special challenge to atmospheric prediction and analysis. The New Jersey and Long Island coasts are at approximate right angles to each other, additionally Long Island is separated from the mainland of Connecticut by Long Island Sound. The various bodies of water in the region (Atlantic Ocean, Long Island Sound, New York Harbor, Jamaica Bay, etc.) have different surface temperatures. In addition the urbanization of the New York areas can modify atmospheric flows. This paper will present results from model simulations, surface observations and remote sensing using the Weather Surveillance Radar - 1988 Doppler (WSR-88D).
Date: April 1, 1998
Creator: Michael, P.; Miller, M. & Tongue, J.S.
Partner: UNT Libraries Government Documents Department

FOAM: Expanding the horizons of climate modeling

Description: We report here on a project that expands the applicability of dynamic climate modeling to very long time scales. The Fast Ocean Atmosphere Model (FOAM) is a coupled ocean atmosphere model that incorporates physics of interest in understanding decade to century time scale variability. It addresses the high computational cost of this endeavor with a combination of improved ocean model formulation, low atmosphere resolution, and efficient coupling. It also uses message passing parallel processing techniques, allowing for the use of cost effective distributed memory platforms. The resulting model runs over 6000 times faster than real time with good fidelity, and has yielded significant results.
Date: October 1, 1997
Creator: Tobis, M.; Foster, I.T. & Schafer, C.M.
Partner: UNT Libraries Government Documents Department

Development of the TRANSIMS environmental module

Description: The TRansportation ANalysis and SIMulation System (TRANSIMS) is one part of the multi-track Travel Model Improvement Program sponsored by the US Department of Transportation, the Environmental Protection Agency, and Department of Energy. Los Alamos National Laboratory is leading this major effort to develop a new, integrated transportation and air quality forecasting procedures necessary to satisfy the Intermodal Surface Transportation Efficiency Act and the Clean Air Act and its amendments. TRANSIMS is a set of integrated analytical and simulation models and supporting data bases. The TRANSIMS methods deal with individual behavioral units and proceed through several steps to estimate travel. TRANSIMS predicts trips for individual households, residents and vehicles rather than for zonal aggregations of households. TRANSIMS also predicts the movement of individual freight loads. A regional microsimulation executes the generated trips on the transportation network, modeling the individual vehicle interactions and predicting the transportation system performance. The purpose of the environmental module is to translate traveler behavior into consequent air quality, energy consumption, and carbon dioxide emissions. Transportation systems play a significant role in urban air quality, energy consumption, and carbon-dioxide emissions.
Date: May 1997
Creator: Williams, M. D.; Thayer, G. & Smith, L. R.
Partner: UNT Libraries Government Documents Department

Turbulence Structure and Implications for Dispersion: Insights from Large-Eddy Simulations

Description: We have presented two flows where detailed knowledge of the fluid mechanics would appear to be crucial for accurate dispersion modeling. We expect that Large-eddy simulations (LES) will complement traditional dispersion modeling by providing both the ability to discern between cases where traditional models work well and cases where more complicated characterizations are necessary, and a method to investigate potentially unique flow features and turbulence structure for specific flow problems.
Date: October 4, 1999
Creator: Calhoun, R; Cederwall, R & Street, R
Partner: UNT Libraries Government Documents Department

Variational optimization of sub-grid scale convection parameters. Final report

Description: Under the DOE CHAMMP/CLIMATE Program, a convective scheme was developed for use in climate models. The purpose of the present study was to develop an adjoint model of its tangent-linear model. the convective scheme was integrated within a single column model which provides radiative-convective equilibrium solutions applicable to climate models. The main goal of this part of the project was to develop an adjoint of the scheme to facilitate the optimization of its convective parameters. For that purpose, adjoint sensitivities were calculated with the adjoint code. Parameter optimization was based on TOGA COARE data which were also used in this study to obtain integrations of the nonlinear and tangent-linear models as well as the integrations of the adjoint model. Some inadequacies of the inner IFA data array were found, and did not permit a single numerical integration during the entire 4 months of data. However, reliable monthly radiative-convective equilibrium solutions and associated adjoint sensitivities were obtained and used to bring about the parameter optimization.
Date: November 25, 1997
Creator: Zivkovic-Rothman, M.
Partner: UNT Libraries Government Documents Department

Intermittent turbulence events observed with a sonic anemometer and minisodar during CASES99.

Description: The Cooperative Air Surface Exchange Study 1999 (CASES99), designed to investigate in detail the nocturnal boundary layer (NBL) of the atmosphere with particular emphasis on turbulence and turbulence events, took place during October 1999, within the Atmospheric Boundary Layer Experiments (ABLE) region east of Wichita KS. The principal measurement site was a heavily instrumented 2-km square located near Leon (LE), KS, but additional sites at Smileyberg (SM) and Beaumont (BE) were also used. The authors augmented the normal ABLE measurements at Beaumont (radar wind profiler, minisodar, 10-m meteorological tower, precipitation gauge) with a sonic anemometer mounted on the tower, 7 m above the surface. For this campaign, the minisodar data were saved in single-pulse mode with no averaging. The Beaumont site is within gently rolling rangeland used primarily for grazing. The site is on a flat plain rising gradually to the east.The Flint Hills escarpment, located approximately 2 km to the east, marks the highest point in, and the eastern boundary of, the Walnut River watershed. Although most terrain features are subtle, terrain effects on atmospheric flows are still possible, particularly in stable conditions. The intent was to observe turbulence and, hopefully, turbulence events with the sonic anemometer and minisodar. The horizontal extent of these occurrences can be studied by including the Beaumont data with those obtained at the Leon site. In this report the authors are concerned with the occurrence of intermittent turbulence.
Date: May 12, 2000
Creator: Coulter, R. L. & Doran, J. C.
Partner: UNT Libraries Government Documents Department

PROBING NEAR-SURFACE ATMOSPHERIC TURBULENCE WITH LIDAR MEASUREMENTS AND HIGH-RESOLUTION HYDRODYNAMIC MODELS

Description: As lidar technology is able to provide fast data collection at a resolution of meters in an atmospheric volume, it is imperative to promote a modeling counterpart of the lidar capability. This paper describes an integrated capability based on data from a scanning water vapor lidar and a high-resolution hydrodynamic model (HIGRAD) equipped with a visualization routine (VIEWER) that simulates the lidar scanning. The purpose is to better understand the spatial and temporal representativeness of the lidar measurements and, in turn, to extend their utility in studying turbulence fields in the atmospheric boundary layer. Raman lidar water vapor data collected over the Pacific warm pool and the simulations with the HIGRAD code are used for identifying the underlying physics and potential aliasing effects of spatially resolved lidar measurements. This capability also helps improve the trade-off between spatial-temporal resolution and coverage of the lidar measurements.
Date: November 1, 2000
Creator: KAO, J.; COOPER, D. & AL, ET
Partner: UNT Libraries Government Documents Department