AIR Model Preflight Analysis

NASA Technical Reports Server (NTRS)

Tai, H.; Wilson, J. W.; Maiden, D. L.

2003-01-01

The atmospheric ionizing radiation (AIR) ER-2 preflight analysis, one of the first attempts to obtain a relatively complete measurement set of the high-altitude radiation level environment, is described in this paper. The primary thrust is to characterize the atmospheric radiation and to define dose levels at high-altitude flight. A secondary thrust is to develop and validate dosimetric techniques and monitoring devices for protecting aircrews. With a few chosen routes, we can measure the experimental results and validate the AIR model predictions. Eventually, as more measurements are made, we gain more understanding about the hazardous radiation environment and acquire more confidence in the prediction models.

The Aliso Canyon Natural Gas Leak : Large Eddy Simulations for Modeling Atmospheric Dynamics and Interpretation of Observations.

NASA Astrophysics Data System (ADS)

Prasad, K.; Thorpe, A. K.; Duren, R. M.; Thompson, D. R.; Whetstone, J. R.

2016-12-01

The National Institute of Standards and Technology (NIST) has supported the development and demonstration of a measurement capability to accurately locate greenhouse gas sources and measure their flux to the atmosphere over urban domains. However, uncertainties in transport models which form the basis of all top-down approaches can significantly affect our capability to attribute sources and predict their flux to the atmosphere. Reducing uncertainties between bottom-up and top-down models will require high resolution transport models as well as validation and verification of dispersion models over an urban domain. Tracer experiments involving the release of Perfluorocarbon Tracers (PFTs) at known flow rates offer the best approach for validating dispersion / transport models. However, tracer experiments are limited by cost, ability to make continuous measurements, and environmental concerns. Natural tracer experiments, such as the leak from the Aliso Canyon underground storage facility offers a unique opportunity to improve and validate high resolution transport models, test leak hypothesis, and to estimate the amount of methane released.High spatial resolution (10 m) Large Eddy Simulations (LES) coupled with WRF atmospheric transport models were performed to simulate the dynamics of the Aliso Canyon methane plume and to quantify the source. High resolution forward simulation results were combined with aircraft and tower based in-situ measurements as well as data from NASA airborne imaging spectrometers. Comparison of simulation results with measurement data demonstrate the capability of the LES models to accurately model transport and dispersion of methane plumes over urban domains.

Validation of Earth atmosphere models using solar EUV observations from the CORONAS and PROBA2 satellites in occultation mode

NASA Astrophysics Data System (ADS)

Slemzin, Vladimir; Ulyanov, Artyom; Gaikovich, Konstantin; Kuzin, Sergey; Pertsov, Andrey; Berghmans, David; Dominique, Marie

2016-02-01

Aims: Knowledge of properties of the Earth's upper atmosphere is important for predicting the lifetime of low-orbit spacecraft as well as for planning operation of space instruments whose data may be distorted by atmospheric effects. The accuracy of the models commonly used for simulating the structure of the atmosphere is limited by the scarcity of the observations they are based on, so improvement of these models requires validation under different atmospheric conditions. Measurements of the absorption of the solar extreme ultraviolet (EUV) radiation in the upper atmosphere below 500 km by instruments operating on low-Earth orbits (LEO) satellites provide efficient means for such validation as well as for continuous monitoring of the upper atmosphere and for studying its response to the solar and geomagnetic activity. Method: This paper presents results of measurements of the solar EUV radiation in the 17 nm wavelength band made with the SPIRIT and TESIS telescopes on board the CORONAS satellites and the SWAP telescope on board the PROBA2 satellite in the occulted parts of the satellite orbits. The transmittance profiles of the atmosphere at altitudes between 150 and 500 km were derived from different phases of solar activity during solar cycles 23 and 24 in the quiet state of the magnetosphere and during the development of a geomagnetic storm. We developed a mathematical procedure based on the Tikhonov regularization method for solution of ill-posed problems in order to retrieve extinction coefficients from the transmittance profiles. The transmittance profiles derived from the data and the retrieved extinction coefficients are compared with simulations carried out with the NRLMSISE-00 atmosphere model maintained by Naval Research Laboratory (USA) and the DTM-2013 model developed at CNES in the framework of the FP7 project ATMOP. Results: Under quiet and slightly disturbed magnetospheric conditions during high and low solar activity the extinction coefficients calculated by both models agreed with the measurements within the data errors. The NRLMSISE-00 model was not able to predict the enhancement of extinction above 300 km observed after 14 h from the beginning of a geomagnetic storm whereas the DTM-2013 model described this variation with good accuracy.

Extending the Confrontation of Weather and Climate Models from Soil Moisture to Surface Flux Data

NASA Astrophysics Data System (ADS)

Dirmeyer, P.; Chen, L.; Wu, J.

2016-12-01

The atmosphere and land components of weather and climate models are typically developed separately and coupled as a last step before new model versions are released. Separate testing of land surface models (LSMs) and atmospheric models is often quite extensive in the development phase, but validation of coupled land-atmosphere behavior is often minimal if performed at all. This is partly because of this piecemeal model development approach and partly because the necessary in situ data to confront coupled land-atmosphere models (LAMs) has been meager until quite recently. Over the past 10-20 years there has been a growing number of networks of measurements of land surface states, surface fluxes, radiation and near-surface meteorology, although they have been largely uncoordinated and frequently incomplete across the range of variables necessary to validate LAMs. We extend recent work "confronting" a variety of LSMs and LAMs with in situ observations of soil moisture from cross-standardized networks to comparisons with measurements of surface latent and sensible heat fluxes at FLUXNET sites in a variety of climate regimes around the world. The motivation is to determine how well LSMs represent observed statistics of variability and co-variability, how much models differ from one another, and how those statistics change when the LSMs are coupled to atmospheric models. Furthermore, comparisons are made to several LAMs in both open-loop (free running) and reanalysis configurations. This shows to what extent data assimilation can constrain the processes involved in flux variability, and helps illuminate model development pathways to improve coupled land-atmosphere interactions in weather and climate models.

Study of atmospheric dynamics

NASA Technical Reports Server (NTRS)

Mcnider, Richard T.; Christy, John R.; Cox, Gregory N.

1993-01-01

In order to better understand the dynamics of the global atmosphere, a data set of precision temperature measurements was developed using the NASA built Microwave Sounding Unit. Modeling research was carried out to validate global model outputs using various satellite data. Idealized flows in a rotating annulus were studied and applied to the general circulation of the atmosphere. Dynamic stratospheric ozone fluctuations were investigated. An extensive bibliography and several reprints are appended.

A cloud model simulation of space shuttle exhaust clouds in different atmospheric conditions

NASA Technical Reports Server (NTRS)

Chen, C.; Zak, J. A.

1989-01-01

A three-dimensional cloud model was used to characterize the dominant influence of the environment on the Space Shuttle exhaust cloud. The model was modified to accept the actual heat and moisture from rocket exhausts and deluge water as initial conditions. An upper-air sounding determined the ambient atmosphere in which the cloud could grow. The model was validated by comparing simulated clouds with observed clouds from four actual Shuttle launches. The model successfully produced clouds with dimensions, rise, decay, liquid water contents and vertical motion fields very similar to observed clouds whose dimensions were calculated from 16 mm film frames. Once validated, the model was used in a number of different atmospheric conditions ranging from very unstable to very stable. In moist, unstable atmospheres simulated clouds rose to about 3.5 km in the first 4 to 8 minutes then decayed. Liquid water contents ranged from 0.3 to 1.0 g kg-1 mixing ratios and vertical motions were from 2 to 10 ms-1. An inversion served both to reduce entrainment (and erosion) at the top and to prevent continued cloud rise. Even in the most unstable atmospheres, the ground cloud did not rise beyond 4 km and in stable atmospheres with strong low level inversions the cloud could be trapped below 500 m. Wind shear strongly affected the appearance of both the ground cloud and vertical column cloud. The ambient low-level atmospheric moisture governed the amount of cloud water in model clouds. Some dry atmospheres produced little or no cloud water. One case of a simulated TITAN rocket explosion is also discussed.

Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

NASA Astrophysics Data System (ADS)

Robinson, Tyler D.; Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard K.; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy A.; Wellnitz, Dennis D.

2011-06-01

The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared.

Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

PubMed

Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

2011-06-01

The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared. Key Words: Astrobiology-Extrasolar terrestrial planets-Habitability-Planetary science-Radiative transfer. Astrobiology 11, 393-408.

Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

NASA Technical Reports Server (NTRS)

Robinson, Tyler D.; Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard; Hearty, Thomas;

Validation and Sensitivity Analysis of a New Atmosphere-Soil-Vegetation Model.

NASA Astrophysics Data System (ADS)

Nagai, Haruyasu

2002-02-01

This paper describes details, validation, and sensitivity analysis of a new atmosphere-soil-vegetation model. The model consists of one-dimensional multilayer submodels for atmosphere, soil, and vegetation and radiation schemes for the transmission of solar and longwave radiations in canopy. The atmosphere submodel solves prognostic equations for horizontal wind components, potential temperature, specific humidity, fog water, and turbulence statistics by using a second-order closure model. The soil submodel calculates the transport of heat, liquid water, and water vapor. The vegetation submodel evaluates the heat and water budget on leaf surface and the downward liquid water flux. The model performance was tested by using measured data of the Cooperative Atmosphere-Surface Exchange Study (CASES). Calculated ground surface fluxes were mainly compared with observations at a winter wheat field, concerning the diurnal variation and change in 32 days of the first CASES field program in 1997, CASES-97. The measured surface fluxes did not satisfy the energy balance, so sensible and latent heat fluxes obtained by the eddy correlation method were corrected. By using options of the solar radiation scheme, which addresses the effect of the direct solar radiation component, calculated albedo agreed well with the observations. Some sensitivity analyses were also done for model settings. Model calculations of surface fluxes and surface temperature were in good agreement with measurements as a whole.

Verification and Validation of COAMPS: Results from a Fully-Coupled Air/Sea/Wave Modeling System

NASA Astrophysics Data System (ADS)

Smith, T.; Allard, R. A.; Campbell, T. J.; Chu, Y. P.; Dykes, J.; Zamudio, L.; Chen, S.; Gabersek, S.

2016-02-01

The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) is a state-of-the art, fully-coupled air/sea/wave modeling system that is currently being validated for operational transition to both the Naval Oceanographic Office (NAVO) and to the Fleet Numerical Meteorology and Oceanography Center (FNMOC). COAMPS is run at the Department of Defense Supercomputing Resource Center (DSRC) operated by the DoD High Performance Computing Modernization Program (HPCMP). A total of four models including the Naval Coastal Ocean Model (NCOM), Simulating Waves Nearshore (SWAN), WaveWatch III, and the COAMPS atmospheric model are coupled through both the Earth System Modeling Framework (ESMF). Results from regions of naval operational interests, including the Western Atlantic (U.S. East Coast), RIMPAC (Hawaii), and DYNAMO (Indian Ocean), will show the advantages of utilizing a coupled modeling system versus an uncoupled or stand alone model. Statistical analyses, which include model/observation comparisons, will be presented in the form of operationally approved scorecards for both the atmospheric and oceanic output. Also, computational logistics involving the HPC resources for the COAMPS simulations will be shown.

Retrieval and Validation of Zenith and Slant Path Delays From the Irish GPS Network

NASA Astrophysics Data System (ADS)

Hanafin, Jennifer; Jennings, S. Gerard; O'Dowd, Colin; McGrath, Ray; Whelan, Eoin

2010-05-01

Retrieval of atmospheric integrated water vapour (IWV) from ground-based GPS receivers and provision of this data product for meteorological applications has been the focus of a number of Europe-wide networks and projects, most recently the EUMETNET GPS water vapour programme. The results presented here are from a project to provide such information about the state of the atmosphere around Ireland for climate monitoring and improved numerical weather prediction. Two geodetic reference GPS receivers have been deployed at Valentia Observatory in Co. Kerry and Mace Head Atmospheric Research Station in Co. Galway, Ireland. These two receivers supplement the existing Ordnance Survey Ireland active network of 17 permanent ground-based receivers. A system to retrieve column-integrated atmospheric water vapour from the data provided by this network has been developed, based on the GPS Analysis at MIT (GAMIT) software package. The data quality of the zenith retrievals has been assessed using co-located radiosondes at the Valentia site and observations from a microwave profiling radiometer at the Mace Head site. Validation of the slant path retrievals requires a numerical weather prediction model and HIRLAM (High-Resolution Limited Area Model) version 7.2, the current operational forecast model in use at Met Éireann for the region, has been used for this validation work. Results from the data processing and comparisons with the independent observations and model will be presented.

Overview of the MEDLI Project

NASA Technical Reports Server (NTRS)

Gazarik, Michael J.; Hwang, Helen; Little, Alan; Cheatwood, Neil; Wright, Michael; Herath, Jeff

2007-01-01

The Mars Science Laboratory Entry, Descent, and Landing Instrumentation (MEDLI) Project's objectives are to measure aerothermal environments, sub-surface heatshield material response, vehicle orientation, and atmospheric density for the atmospheric entry and descent phases of the Mars Science Laboratory (MSL) entry vehicle. The flight science objectives of MEDLI directly address the largest uncertainties in the ability to design and validate a robust Mars entry system, including aerothermal, aerodynamic and atmosphere models, and thermal protection system (TPS) design. The instrumentation suite will be installed in the heatshield of the MSL entry vehicle. The acquired data will support future Mars entry and aerocapture missions by providing measured atmospheric data to validate Mars atmosphere models and clarify the design margins for future Mars missions. MEDLI thermocouple and recession sensor data will significantly improve the understanding of aeroheating and TPS performance uncertainties for future missions. MEDLI pressure data will permit more accurate trajectory reconstruction, as well as separation of aerodynamic and atmospheric uncertainties in the hypersonic and supersonic regimes. This paper provides an overview of the project including the instrumentation design, system architecture, and expected measurement response.

Overview of the MEDLI Project

NASA Technical Reports Server (NTRS)

Gazarik, Michael J.; Little, Alan; Cheatwood, F. Neil; Wright, Michael J.; Herath, Jeff A.; Martinez, Edward R.; Munk, Michelle; Novak, Frank J.; Wright, Henry S.

2008-01-01

The Mars Science Laboratory Entry, Descent, and Landing Instrumentation (MEDLI) Project s objectives are to measure aerothermal environments, sub-surface heatshield material response, vehicle orientation, and atmospheric density for the atmospheric entry and descent phases of the Mars Science Laboratory (MSL) entry vehicle. The flight science objectives of MEDLI directly address the largest uncertainties in the ability to design and validate a robust Mars entry system, including aerothermal, aerodynamic and atmosphere models, and thermal protection system (TPS) design. The instrumentation suite will be installed in the heatshield of the MSL entry vehicle. The acquired data will support future Mars entry and aerocapture missions by providing measured atmospheric data to validate Mars atmosphere models and clarify the design margins for future Mars missions. MEDLI thermocouple and recession sensor data will significantly improve the understanding of aeroheating and TPS performance uncertainties for future missions. MEDLI pressure data will permit more accurate trajectory reconstruction, as well as separation of aerodynamic and atmospheric uncertainties in the hypersonic and supersonic regimes. This paper provides an overview of the project including the instrumentation design, system architecture, and expected measurement response.

The 2006 Kennedy Space Center Range Reference Atmosphere Model Validation Study and Sensitivity Analysis to the Performance of the National Aeronautics and Space Administration's Space Shuttle Vehicle

NASA Technical Reports Server (NTRS)

Burns, Lee; Decker, Ryan; Harrington, Brian; Merry, Carl

2008-01-01

The Kennedy Space Center (KSC) Range Reference Atmosphere (RRA) is a statistical model that summarizes wind and thermodynamic atmospheric variability from surface to 70 km. The National Aeronautics and Space Administration's (NASA) Space Shuttle program, which launches from KSC, utilizes the KSC RRA data to evaluate environmental constraints on various aspects of the vehicle during ascent. An update to the KSC RRA was recently completed. As part of the update, the Natural Environments Branch at NASA's Marshall Space Flight Center (MSFC) conducted a validation study and a comparison analysis to the existing KSC RRA database version 1983. Assessments to the Space Shuttle vehicle ascent profile characteristics were performed by JSC/Ascent Flight Design Division to determine impacts of the updated model to the vehicle performance. Details on the model updates and the vehicle sensitivity analyses with the update model are presented.

Ablator Response Model Development: From Flight Data Back to Fundamental Experiments

NASA Technical Reports Server (NTRS)

Mansour, Nagi N.; Lachaud, Jean R.

2013-01-01

The successful Mars atmospheric entry by the Mars Science Laboratory (MSL-Curiosity) combined with the success of the Earth atmospheric entry by the Stardust capsule have established PICA as a major Thermal Protection Systems (TPS) material. We expect that this class of materials will be on the short list selected by NASA for any atmospheric entry missions and that it will be the lead of that list of materials in any planning, feasibility studies or flight readiness studies. In addition to NASAs successes, the Dragon capsule, the successful commercial space vehicle built by SpaceX, uses PICA-X, while the European Space Agency is considering ASTERM for its exploration missions that involve atmospheric entries, both of these materials are of the same family as PICA. In the talk, a high-fidelity model will be detailed and discussed. The model tracks the chemical composition of the gases produced during pyrolysis. As in the conventional models, it uses equilibrium chemistry to determine the recession rate at high temperatures but switches to in-volume finite-rate ablation for lower temperatures. It also tracks the time evolution of the porosity of the material. Progress in implementing this high-fidelity model in a code will be presented. In addition, a set of basic experimental data being supported for model validation will be summarized. The validation process for the model development will be discussed. Preliminary results will be presented for a case where detailed pyrolysis product chemistry is computed. Finally, a wish list for a set of validation experiments will be outlined and discussed.

Development and validation of a regional coupled forecasting system for S2S forecasts

NASA Astrophysics Data System (ADS)

Sun, R.; Subramanian, A. C.; Hoteit, I.; Miller, A. J.; Ralph, M.; Cornuelle, B. D.

2017-12-01

Accurate and efficient forecasting of oceanic and atmospheric circulation is essential for a wide variety of high-impact societal needs, including: weather extremes; environmental protection and coastal management; management of fisheries, marine conservation; water resources; and renewable energy. Effective forecasting relies on high model fidelity and accurate initialization of the models with observed state of the ocean-atmosphere-land coupled system. A regional coupled ocean-atmosphere model with the Weather Research and Forecasting (WRF) model and the MITGCM ocean model coupled using the ESMF (Earth System Modeling Framework) coupling framework is developed to resolve mesoscale air-sea feedbacks. The regional coupled model allows oceanic mixed layer heat and momentum to interact with the atmospheric boundary layer dynamics at the mesoscale and submesoscale spatiotemporal regimes, thus leading to feedbacks which are otherwise not resolved in coarse resolution global coupled forecasting systems or regional uncoupled forecasting systems. The model is tested in two scenarios in the mesoscale eddy rich Red Sea and Western Indian Ocean region as well as mesoscale eddies and fronts of the California Current System. Recent studies show evidence for air-sea interactions involving the oceanic mesoscale in these two regions which can enhance predictability on sub seasonal timescale. We will present results from this newly developed regional coupled ocean-atmosphere model for forecasts over the Red Sea region as well as the California Current region. The forecasts will be validated against insitu observations in the region as well as reanalysis fields.

Stratospheric ozone - Fragile shield. [SST exhausts and Freons impact

NASA Technical Reports Server (NTRS)

Hoffert, M. I.; Stewart, R. W.

1975-01-01

Atmospheric models that have been used in major studies on the possible impact of SST exhausts and Freons on stratospheric ozone are discussed and compared. An overview is given of ozone-reduction estimates that they produce, together with an assessment of possible effects of atmospheric testing of thermonuclear bombs in an attempt to find direct observational evidence for ozone depletion resulting from human activities. It is concluded that clear validation of atmospheric-model predictions is lacking.

Simulation of Subpixel Atmospherically Degraded Target Detectability in Cluttered Scenes

DTIC Science & Technology

2013-09-06

Number: The scientific or technical validity of this Contract Report is entirely the responsibility of the Contractor and the contents do not necessarily...September 6th 2012 and September 6th 2013. Results: Significant and representative cases are modeled and results are presented in an annex of the...3 4 Modeling an image degraded by the atmosphere

Atmospheric stability and complex terrain: comparing measurements and CFD

NASA Astrophysics Data System (ADS)

Koblitz, T.; Bechmann, A.; Berg, J.; Sogachev, A.; Sørensen, N.; Réthoré, P.-E.

2014-12-01

For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface layer. So far, physical processes that are specific to the atmospheric boundary layer, for example the Coriolis force, buoyancy forces and heat transport, are mostly ignored in state-of-the-art flow solvers. In order to decrease the uncertainty of wind resource assessment, the effect of thermal stratification on the atmospheric boundary layer should be included in such models. The present work focuses on non-neutral atmospheric flow over complex terrain including physical processes like stability and Coriolis force. We examine the influence of these effects on the whole atmospheric boundary layer using the DTU Wind Energy flow solver EllipSys3D. To validate the flow solver, measurements from Benakanahalli hill, a field experiment that took place in India in early 2010, are used. The experiment was specifically designed to address the combined effects of stability and Coriolis force over complex terrain, and provides a dataset to validate flow solvers. Including those effects into EllipSys3D significantly improves the predicted flow field when compared against the measurements.

Optical observables in stars with non-stationary atmospheres. [fireballs and cepheid models

NASA Technical Reports Server (NTRS)

Hillendahl, R. W.

1980-01-01

Experience gained by use of Cepheid modeling codes to predict the dimensional and photometric behavior of nuclear fireballs is used as a means of validating various computational techniques used in the Cepheid codes. Predicted results from Cepheid models are compared with observations of the continuum and lines in an effort to demonstrate that the atmospheric phenomena in Cepheids are quite complex but that they can be quantitatively modeled.

Experimental evaluation of atmospheric effects on radiometric measurements using the EREP of Skylab. [Salton Sea and Great Salt Lake

NASA Technical Reports Server (NTRS)

Chang, D. T. (Principal Investigator); Isaacs, R. G.

1975-01-01

The author has identified the following significant results. Test sites were located near the Great Salt Lake and the Salton Sea. Calculations were performed for a set of atmospheric models corresponding to the test sites, in addition to standard models for summer and winter midlatitude atmospheres with respective integrated water vapor amount of 2.4 g/sq cm and 0.9 g/sq cm. Each atmosphere was found to contain an average amount of continental aerosol. Computations were valid for high solar elevation angles. Atmospheric attenuation quantities were computed in addition to simulated EREP S192 radiances.

A Portable Ground-Based Atmospheric Monitoring System (PGAMS) for the Calibration and Validation of Atmospheric Correction Algorithms Applied to Aircraft and Satellite Images

NASA Technical Reports Server (NTRS)

Schiller, Stephen; Luvall, Jeffrey C.; Rickman, Doug L.; Arnold, James E. (Technical Monitor)

2000-01-01

Detecting changes in the Earth's environment using satellite images of ocean and land surfaces must take into account atmospheric effects. As a result, major programs are underway to develop algorithms for image retrieval of atmospheric aerosol properties and atmospheric correction. However, because of the temporal and spatial variability of atmospheric transmittance it is very difficult to model atmospheric effects and implement models in an operational mode. For this reason, simultaneous in situ ground measurements of atmospheric optical properties are vital to the development of accurate atmospheric correction techniques. Presented in this paper is a spectroradiometer system that provides an optimized set of surface measurements for the calibration and validation of atmospheric correction algorithms. The Portable Ground-based Atmospheric Monitoring System (PGAMS) obtains a comprehensive series of in situ irradiance, radiance, and reflectance measurements for the calibration of atmospheric correction algorithms applied to multispectral. and hyperspectral images. The observations include: total downwelling irradiance, diffuse sky irradiance, direct solar irradiance, path radiance in the direction of the north celestial pole, path radiance in the direction of the overflying satellite, almucantar scans of path radiance, full sky radiance maps, and surface reflectance. Each of these parameters are recorded over a wavelength range from 350 to 1050 nm in 512 channels. The system is fast, with the potential to acquire the complete set of observations in only 8 to 10 minutes depending on the selected spatial resolution of the sky path radiance measurements

Genetic programming-based mathematical modeling of influence of weather parameters in BOD5 removal by Lemna minor.

PubMed

Chandrasekaran, Sivapragasam; Sankararajan, Vanitha; Neelakandhan, Nampoothiri; Ram Kumar, Mahalakshmi

2017-11-04

This study, through extensive experiments and mathematical modeling, reveals that other than retention time and wastewater temperature (T w ), atmospheric parameters also play important role in the effective functioning of aquatic macrophyte-based treatment system. Duckweed species Lemna minor is considered in this study. It is observed that the combined effect of atmospheric temperature (T atm ), wind speed (U w ), and relative humidity (RH) can be reflected through one parameter, namely the "apparent temperature" (T a ). A total of eight different models are considered based on the combination of input parameters and the best mathematical model is arrived at which is validated through a new experimental set-up outside the modeling period. The validation results are highly encouraging. Genetic programming (GP)-based models are found to reveal deeper understandings of the wetland process.

Structure of the tropical lower stratosphere as revealed by three reanalysis data sets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pawson, S.; Fiorino, M.

1996-05-01

While the skill of climate simulation models has advanced over the last decade, mainly through improvements in modeling, further progress will depend on the availability and the quality of comprehensive validation data sets covering long time periods. A new source of such validation data is atmospheric {open_quotes}reanalysis{close_quotes} where a fixed, state-of-the-art global atmospheric model/data assimilation system is run through archived and recovered observations to produce a consistent set of atmospheric analyses. Although reanalysis will be free of non-physical variability caused by changes in the models and/or the assimilation procedure, it is necessary to assess its quality. A region for stringentmore » testing of the quality of reanalysis is the tropical lower stratosphere. This portion of the atmosphere is sparse in observations but displays the prominent quasi-biennial oscillation (QBO) and an annual cycle, neither of which is fully understood, but which are likely coupled dynamically. We first consider the performance of three reanalyses, from NCEP/NCAR, NASA and ECMWF, against rawinsonde data in depicting the QBO and then examine the structure of the tropical lower stratosphere in NCEP and ECMWF data sets in detail. While the annual cycle and the QBO in wind and temperature are quite successfully represented, the mean meridional circulations in NCEP and ECMWF data sets contain unusual features which may be due to the assimilation process rather than being physically based. Further, the models capture the long-term temperature fluctuations associated with volcanic eruptions, even though the physical mechanisms are not included, thus implying that the model does not mask prominent stratospheric signals in the observational data. We conclude that reanalysis offers a unique opportunity to better understand the dynamics of QBO and can be applied to climate model validation.« less

Analysis of longwave radiation for the Earth-atmosphere system

NASA Technical Reports Server (NTRS)

Tiwari, S. N.; Venuru, C. S.; Subramanian, S. V.

1983-01-01

Accurate radiative transfer models are used to determine the upwelling atmospheric radiance and net radiative flux in the entire longwave spectral range. The validity of the quasi-random band model is established by comparing the results of this model with those of line-by-line formulations and with available theoretical and experimental results. Existing radiative transfer models and computer codes are modified to include various surface and atmospheric effects (surface reflection, nonequilibrium radiation, and cloud effects). The program is used to evaluate the radiative flux in clear atmosphere, provide sensitivity analysis of upwelling radiance in the presence of clouds, and determine the effects of various climatological parameters on the upwelling radiation and anisotropic function. Homogeneous and nonhomogeneous gas emissivities can also be evaluated under different conditions.

Earth as an Extrasolar Planet: Earth Model Validation Using EPOXI Earth Observations

PubMed Central

Meadows, Victoria S.; Crisp, David; Deming, Drake; A'Hearn, Michael F.; Charbonneau, David; Livengood, Timothy A.; Seager, Sara; Barry, Richard K.; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M.; McFadden, Lucy A.; Wellnitz, Dennis D.

2011-01-01

Abstract The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be used to simulate Earth's time-dependent brightness and spectral properties for wavelengths from the far ultraviolet to the far infrared. Key Words: Astrobiology—Extrasolar terrestrial planets—Habitability—Planetary science—Radiative transfer. Astrobiology 11, 393–408. PMID:21631250

Explicit validation of a surface shortwave radiation balance model over snow-covered complex terrain

NASA Astrophysics Data System (ADS)

Helbig, N.; Löwe, H.; Mayer, B.; Lehning, M.

2010-09-01

A model that computes the surface radiation balance for all sky conditions in complex terrain is presented. The spatial distribution of direct and diffuse sky radiation is determined from observations of incident global radiation, air temperature, and relative humidity at a single measurement location. Incident radiation under cloudless sky is spatially derived from a parameterization of the atmospheric transmittance. Direct and diffuse sky radiation for all sky conditions are obtained by decomposing the measured global radiation value. Spatial incident radiation values under all atmospheric conditions are computed by adjusting the spatial radiation values obtained from the parametric model with the radiation components obtained from the decomposition model at the measurement site. Topographic influences such as shading are accounted for. The radiosity approach is used to compute anisotropic terrain reflected radiation. Validations of the shortwave radiation balance model are presented in detail for a day with cloudless sky. For a day with overcast sky a first validation is presented. Validation of a section of the horizon line as well as of individual radiation components is performed with high-quality measurements. A new measurement setup was designed to determine terrain reflected radiation. There is good agreement between the measurements and the modeled terrain reflected radiation values as well as with incident radiation values. A comparison of the model with a fully three-dimensional radiative transfer Monte Carlo model is presented. That validation reveals a good agreement between modeled radiation values.

Experimental validation of a millimeter wave radar technique to remotely sense atmospheric pressure at the Earth's surface

NASA Technical Reports Server (NTRS)

Flower, D. A.; Peckham, G. E.; Bradford, W. J.

1984-01-01

Experiments with a millimeter wave radar operating on the NASA CV-990 aircraft which validate the technique for remotely sensing atmospheric pressure at the Earth's surface are described. Measurements show that the precise millimeter wave observations needed to deduce pressure from space with an accuracy of 1 mb are possible, that sea surface reflection properties agree with theory and that the measured variation of differential absorption with altitude corresponds to that expected from spectroscopic models.

Atmosphere behavior in gas-closed mouse-algal systems - An experimental and modelling study

NASA Technical Reports Server (NTRS)

Averner, M. M.; Moore, B., III; Bartholomew, I.; Wharton, R.

1984-01-01

A NASA-sponsored research program initiated using mathematical modelling and laboratory experimentation aimed at examining the gas-exchange characteristics of artificial animal/plant systems closed to the ambient atmosphere is studied. The development of control techniques and management strategies for maintaining the atmospheric levels of carbon dioxide and oxygen at physiological levels is considered. A mathematical model simulating the behavior of a gas-closed mouse-algal system under varying environmental conditions is described. To verify and validate the model simulations, an analytical system with which algal growth and gas exchange characteristics can be manipulated and measured is designed, fabricated, and tested. The preliminary results are presented.

Atmosphere Assessment for MARS Science Laboratory Entry, Descent and Landing Operations

NASA Technical Reports Server (NTRS)

Cianciolo, Alicia D.; Cantor, Bruce; Barnes, Jeff; Tyler, Daniel, Jr.; Rafkin, Scot; Chen, Allen; Kass, David; Mischna, Michael; Vasavada, Ashwin R.

2013-01-01

On August 6, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed on the surface of Mars. The Entry, Descent and Landing (EDL) sequence was designed using atmospheric conditions estimated from mesoscale numerical models. The models, developed by two independent organizations (Oregon State University and the Southwest Research Institute), were validated against observations at Mars from three prior years. In the weeks and days before entry, the MSL "Council of Atmospheres" (CoA), a group of atmospheric scientists and modelers, instrument experts and EDL simulation engineers, evaluated the latest Mars data from orbiting assets including the Mars Reconnaissance Orbiter's Mars Color Imager (MARCI) and Mars Climate Sounder (MCS), as well as Mars Odyssey's Thermal Emission Imaging System (THEMIS). The observations were compared to the mesoscale models developed for EDL performance simulation to determine if a spacecraft parameter update was necessary prior to entry. This paper summarizes the daily atmosphere observations and comparison to the performance simulation atmosphere models. Options to modify the atmosphere model in the simulation to compensate for atmosphere effects are also presented. Finally, a summary of the CoA decisions and recommendations to the MSL project in the days leading up to EDL is provided.

Development of atmospheric N2O isotopomers model based on a chemistry-coupled atmospheric general circulation model

NASA Astrophysics Data System (ADS)

Ishijima, K.; Toyoda, S.; Sudo, K.; Yoshikawa, C.; Nanbu, S.; Aoki, S.; Nakazawa, T.; Yoshida, N.

2009-12-01

It is well known that isotopic information is useful to qualitatively understand cycles and constrain sources of some atmospheric species, but so far there has been no study to model N2O isotopomers throughout the atmosphere from the troposphere to the stratosphere, including realistic surface N2O isotopomers emissions. We have started to develop a model to simulate spatiotemporal variations of the atmospheric N2O isotopomers in both the troposphere and the stratosphere, based on a chemistry-coupled atmospheric general circulation model, in order to obtain more accurate quantitative understanding of the global N2O cycle. For surface emissions of the isotopomers, combination of EDGAR-based anthropogenic and soil fluxes and monthly varying GEIA oceanic fluxes are factored, using isotopic values of global total sources estimated from firn-air analyses based long-term trend of the atmospheric N2O isotopomers. Isotopic fractionations in chemical reactions are considered for photolysis and photo-oxidation of N2O in the stratosphere. The isotopic fractionation coefficients have been employed from studies based on laboratory experiments, but we also will test the coefficients determined by theoretical calculations. In terms of the global N2O isotopomer budgets, precise quantification of the sources is quite challenging, because even the spatiotemporal variabilities of N2O sources have never been adequately estimated. Therefore, we have firstly started validation of simulated isotopomer results in the stratosphere, by using the isotopomer profiles obtained by balloon observations. N2O concentration profiles are mostly well reproduced, partly because of realistic reproduction of dynamical processes by nudging with reanalysis meteorological data. However, the concentration in the polar vortex tends to be overestimated, probably due to relatively coarse wave-length resolution in photolysis calculation. Such model features also appear in the isotopomers results, which are almost underestimated, relative to the balloon observations, although the concentration is well simulated. The tendency has been somewhat improved by incorporating another photolysis scheme with slightly higher wave-length resolution into the model. From another point of view, these facts indicate that N2O isotopomers can be used for validation of the stratospheric photochemical calculations in model, because of very high sensitivity of the isotopomer ratio values to some settings such as the wave-length resolution in the photochemical scheme.Therefore, N2O isotopomers modeling seems to be not only useful for validation of the fractionation coefficients and of isotopic characterization of sources, but also have the possibility to be an index especially for precision in the stratospheric photolysis in model.

Sensitivity of Precipitation in Coupled Land-Atmosphere Models

NASA Technical Reports Server (NTRS)

Neelin, David; Zeng, N.; Suarez, M.; Koster, R.

2004-01-01

The project objective was to understand mechanisms by which atmosphere-land-ocean processes impact precipitation in the mean climate and interannual variations, focusing on tropical and subtropical regions. A combination of modeling tools was used: an intermediate complexity land-atmosphere model developed at UCLA known as the QTCM and the NASA Seasonal-to-Interannual Prediction Program general circulation model (NSIPP GCM). The intermediate complexity model was used to develop hypotheses regarding the physical mechanisms and theory for the interplay of large-scale dynamics, convective heating, cloud radiative effects and land surface feedbacks. The theoretical developments were to be confronted with diagnostics from the more complex GCM to validate or modify the theory.

Finite-Difference Modeling of Acoustic and Gravity Wave Propagation in Mars Atmosphere: Application to Infrasounds Emitted by Meteor Impacts

NASA Astrophysics Data System (ADS)

Garcia, Raphael F.; Brissaud, Quentin; Rolland, Lucie; Martin, Roland; Komatitsch, Dimitri; Spiga, Aymeric; Lognonné, Philippe; Banerdt, Bruce

2017-10-01

The propagation of acoustic and gravity waves in planetary atmospheres is strongly dependent on both wind conditions and attenuation properties. This study presents a finite-difference modeling tool tailored for acoustic-gravity wave applications that takes into account the effect of background winds, attenuation phenomena (including relaxation effects specific to carbon dioxide atmospheres) and wave amplification by exponential density decrease with height. The simulation tool is implemented in 2D Cartesian coordinates and first validated by comparison with analytical solutions for benchmark problems. It is then applied to surface explosions simulating meteor impacts on Mars in various Martian atmospheric conditions inferred from global climate models. The acoustic wave travel times are validated by comparison with 2D ray tracing in a windy atmosphere. Our simulations predict that acoustic waves generated by impacts can refract back to the surface on wind ducts at high altitude. In addition, due to the strong nighttime near-surface temperature gradient on Mars, the acoustic waves are trapped in a waveguide close to the surface, which allows a night-side detection of impacts at large distances in Mars plains. Such theoretical predictions are directly applicable to future measurements by the INSIGHT NASA Discovery mission.

Free Radicals and Reactive Intermediates for the SAGE III Ozone Loss and Validation Experiment (SOLVE) Mission

NASA Technical Reports Server (NTRS)

Anderson, James G.

2001-01-01

This grant provided partial support for participation in the SAGE III Ozone Loss and Validation Experiment. The NASA-sponsored SOLVE mission was conducted Jointly with the European Commission-sponsored Third European Stratospheric Experiment on Ozone (THESEO 2000). Researchers examined processes that control ozone amounts at mid to high latitudes during the arctic winter and acquired correlative data needed to validate the Stratospheric Aerosol and Gas Experiment (SAGE) III satellite measurements that are used to quantitatively assess high-latitude ozone loss. The campaign began in September 1999 with intercomparison flights out of NASA Dryden Flight Research Center in Edwards. CA. and continued through March 2000. with midwinter deployments out of Kiruna. Sweden. SOLVE was co-sponsored by the Upper Atmosphere Research Program (UARP). Atmospheric Effects of Aviation Project (AEAP). Atmospheric Chemistry Modeling and Analysis Program (ACMAP). and Earth Observing System (EOS) of NASA's Earth Science Enterprise (ESE) as part of the validation program for the SAGE III instrument.

A Biomass-based Model to Estimate the Plausibility of Exoplanet Biosignature Gases

NASA Astrophysics Data System (ADS)

Seager, S.; Bains, W.; Hu, R.

2013-10-01

Biosignature gas detection is one of the ultimate future goals for exoplanet atmosphere studies. We have created a framework for linking biosignature gas detectability to biomass estimates, including atmospheric photochemistry and biological thermodynamics. The new framework is intended to liberate predictive atmosphere models from requiring fixed, Earth-like biosignature gas source fluxes. New biosignature gases can be considered with a check that the biomass estimate is physically plausible. We have validated the models on terrestrial production of NO, H2S, CH4, CH3Cl, and DMS. We have applied the models to propose NH3 as a biosignature gas on a "cold Haber World," a planet with a N2-H2 atmosphere, and to demonstrate why gases such as CH3Cl must have too large of a biomass to be a plausible biosignature gas on planets with Earth or early-Earth-like atmospheres orbiting a Sun-like star. To construct the biomass models, we developed a functional classification of biosignature gases, and found that gases (such as CH4, H2S, and N2O) produced from life that extracts energy from chemical potential energy gradients will always have false positives because geochemistry has the same gases to work with as life does, and gases (such as DMS and CH3Cl) produced for secondary metabolic reasons are far less likely to have false positives but because of their highly specialized origin are more likely to be produced in small quantities. The biomass model estimates are valid to one or two orders of magnitude; the goal is an independent approach to testing whether a biosignature gas is plausible rather than a precise quantification of atmospheric biosignature gases and their corresponding biomasses.

Atmospheric transport of persistent organic pollutants - development of a 3-d dynamical transport model covering the northern hemisphere

NASA Astrophysics Data System (ADS)

Hansen, K. M.; Christensen, J. H.; Geels, C.; Frohn, L. M.; Brandt, J.

2003-04-01

The Danish Eulerian Hemispheric Model (DEHM) is a 3-D dynamical atmospheric transport model originally developed to describe the atmospheric transport of sulphur, lead, and mercury to the Arctic. The model has been validated carefully for these compounds. A new version of DEHM is currently being developed to describe the atmospheric transport of persistent organic pollutants (POPs) which are toxic, lipophilic and bio-accumulating compounds showing great persistence in the environment. The model has a horizontal resolution of 150 km x 150 km and 18 vertical layers, and it is driven by meteorological data from the numerical weather prediction model MM5V2. During environmental cycling POPs can be deposited and re-emitted several times before reaching a final destination. A description of the exchange processes between the land/ocean surfaces and the atmosphere is included in the model to account for this multi-hop transport. The present model version describes the atmospheric transport of the pesticide alpha-hexachlorocyclohexane (alpha-HCH). Other POPs may be included when proper data on emissions and physical-chemical parameters becomes available. The model-processes and the first model results are presented. The atmospheric transport of alpha-HCH for the 1990s is well described by the model.

Sonic Boom Modeling Technical Challenge

NASA Technical Reports Server (NTRS)

Sullivan, Brenda M.

2007-01-01

This viewgraph presentation reviews the technical challenges in modeling sonic booms. The goal of this program is to develop knowledge, capabilities and technologies to enable overland supersonic flight. The specific objectives of the modeling are: (1) Develop and validate sonic boom propagation model through realistic atmospheres, including effects of turbulence (2) Develop methods enabling prediction of response of and acoustic transmission into structures impacted by sonic booms (3) Develop and validate psychoacoustic model of human response to sonic booms under both indoor and outdoor listening conditions, using simulators.

Coupling of an aeroacoustic model and a parabolic equation code for long range wind turbine noise propagation

NASA Astrophysics Data System (ADS)

Cotté, B.

2018-05-01

This study proposes to couple a source model based on Amiet's theory and a parabolic equation code in order to model wind turbine noise emission and propagation in an inhomogeneous atmosphere. Two broadband noise generation mechanisms are considered, namely trailing edge noise and turbulent inflow noise. The effects of wind shear and atmospheric turbulence are taken into account using the Monin-Obukhov similarity theory. The coupling approach, based on the backpropagation method to preserve the directivity of the aeroacoustic sources, is validated by comparison with an analytical solution for the propagation over a finite impedance ground in a homogeneous atmosphere. The influence of refraction effects is then analyzed for different directions of propagation. The spectrum modification related to the ground effect and the presence of a shadow zone for upwind receivers are emphasized. The validity of the point source approximation that is often used in wind turbine noise propagation models is finally assessed. This approximation exaggerates the interference dips in the spectra, and is not able to correctly predict the amplitude modulation.

ADAM-M Data and Information

Atmospheric Science Data Center

2017-05-11

... Information Creating a Unified Airborne Database for Assessment and Validation of Global Models of Atmospheric ...  (3)  To generate a standardized in-situ observational database with best possible matching temporal and spatial scales to model ...

The Use of CASES-97 Observations to Assess and Parameterize the Impact of Land-Surface Heterogeneity on Area-Average Surface Heat Fluxes for Large-Scale Coupled Atmosphere-Hydrology Models

NASA Technical Reports Server (NTRS)

Chen, Fei; Yates, David; LeMone, Margaret

2001-01-01

To understand the effects of land-surface heterogeneity and the interactions between the land-surface and the planetary boundary layer at different scales, we develop a multiscale data set. This data set, based on the Cooperative Atmosphere-Surface Exchange Study (CASES97) observations, includes atmospheric, surface, and sub-surface observations obtained from a dense observation network covering a large region on the order of 100 km. We use this data set to drive three land-surface models (LSMs) to generate multi-scale (with three resolutions of 1, 5, and 10 kilometers) gridded surface heat flux maps for the CASES area. Upon validating these flux maps with measurements from surface station and aircraft, we utilize them to investigate several approaches for estimating the area-integrated surface heat flux for the CASES97 domain of 71x74 square kilometers, which is crucial for land surface model development/validation and area water and energy budget studies. This research is aimed at understanding the relative contribution of random turbulence versus organized mesoscale circulations to the area-integrated surface flux at the scale of 100 kilometers, and identifying the most important effective parameters for characterizing the subgrid-scale variability for large-scale atmosphere-hydrology models.

The great American solar eclipse of August 21, 2017; new understanding of the response of the upper atmosphere and ionosphere.

NASA Astrophysics Data System (ADS)

Drob, D. P.; Huba, J.; Kordella, L.; Earle, G. D.; Ridley, A. J.

2017-12-01

The great American solar eclipse of August 21, 2017 provides a unique opportunity to study the basic physics of the upper atmosphere and ionosphere. While the effects of solar eclipses on the upper atmosphere and ionosphere have been studied since the 1930s, and later matured in the last several decades, recent advances in first principles numerical models and multi-instrument observational capabilities continue to provide new insights. Upper atmospheric eclipse phenomena such as ionospheric conjugate effects and the generation of a thermospheric bow wave that propagates into the nightside are simulated with high-resolution first principles upper atmospheric models and compared with observations to validate this understanding.

Advancing a Model-Validated Statistical Method for Decomposing the Key Oceanic Drivers of Regional Climate: Focus on Northern and Tropical African Climate Variability in the Community Earth System Model (CESM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Fuyao; Yu, Yan; Notaro, Michael

This study advances the practicality and stability of the traditional multivariate statistical method, generalized equilibrium feedback assessment (GEFA), for decomposing the key oceanic drivers of regional atmospheric variability, especially when available data records are short. An advanced stepwise GEFA methodology is introduced, in which unimportant forcings within the forcing matrix are eliminated through stepwise selection. Method validation of stepwise GEFA is performed using the CESM, with a focused application to northern and tropical Africa (NTA). First, a statistical assessment of the atmospheric response to each primary oceanic forcing is carried out by applying stepwise GEFA to a fully coupled controlmore » run. Then, a dynamical assessment of the atmospheric response to individual oceanic forcings is performed through ensemble experiments by imposing sea surface temperature anomalies over focal ocean basins. Finally, to quantify the reliability of stepwise GEFA, the statistical assessment is evaluated against the dynamical assessment in terms of four metrics: the percentage of grid cells with consistent response sign, the spatial correlation of atmospheric response patterns, the area-averaged seasonal cycle of response magnitude, and consistency in associated mechanisms between assessments. In CESM, tropical modes, namely El Niño–Southern Oscillation and the tropical Indian Ocean Basin, tropical Indian Ocean dipole, and tropical Atlantic Niño modes, are the dominant oceanic controls of NTA climate. In complementary studies, stepwise GEFA is validated in terms of isolating terrestrial forcings on the atmosphere, and observed oceanic and terrestrial drivers of NTA climate are extracted to establish an observational benchmark for subsequent coupled model evaluation and development of process-based weights for regional climate projections.« less

Advancing a Model-Validated Statistical Method for Decomposing the Key Oceanic Drivers of Regional Climate: Focus on Northern and Tropical African Climate Variability in the Community Earth System Model (CESM)

DOE PAGES

Wang, Fuyao; Yu, Yan; Notaro, Michael; ...

2017-09-27

This study advances the practicality and stability of the traditional multivariate statistical method, generalized equilibrium feedback assessment (GEFA), for decomposing the key oceanic drivers of regional atmospheric variability, especially when available data records are short. An advanced stepwise GEFA methodology is introduced, in which unimportant forcings within the forcing matrix are eliminated through stepwise selection. Method validation of stepwise GEFA is performed using the CESM, with a focused application to northern and tropical Africa (NTA). First, a statistical assessment of the atmospheric response to each primary oceanic forcing is carried out by applying stepwise GEFA to a fully coupled controlmore » run. Then, a dynamical assessment of the atmospheric response to individual oceanic forcings is performed through ensemble experiments by imposing sea surface temperature anomalies over focal ocean basins. Finally, to quantify the reliability of stepwise GEFA, the statistical assessment is evaluated against the dynamical assessment in terms of four metrics: the percentage of grid cells with consistent response sign, the spatial correlation of atmospheric response patterns, the area-averaged seasonal cycle of response magnitude, and consistency in associated mechanisms between assessments. In CESM, tropical modes, namely El Niño–Southern Oscillation and the tropical Indian Ocean Basin, tropical Indian Ocean dipole, and tropical Atlantic Niño modes, are the dominant oceanic controls of NTA climate. In complementary studies, stepwise GEFA is validated in terms of isolating terrestrial forcings on the atmosphere, and observed oceanic and terrestrial drivers of NTA climate are extracted to establish an observational benchmark for subsequent coupled model evaluation and development of process-based weights for regional climate projections.« less

The Atmospheric Infrared Sounder- An Overview

NASA Technical Reports Server (NTRS)

Larnbrigtsen, Bjorn; Fetzer, Eric; Lee, Sung-Yung; Irion, Fredrick; Hearty, Thomas; Gaiser, Steve; Pagano, Thomas; Aumann, Hartmut; Chahine, Moustafa

2004-01-01

The Atmospheric Infrared Sounder (AIRS) was launched in May 2002. Along with two companion microwave sensors, it forms the AIRS Sounding Suite. This system is the most advanced atmospheric sounding system to date, with measurement accuracies far surpassing those available on current weather satellites. The data products are calibrated radiances from all three sensors and a number of derived geophysical parameters, including vertical temperature and humidity profiles, surface temperature, cloud fraction, cIoud top pressure, and profiles of ozone. These products are generated under cloudy as well as clear conditions. An ongoing calibration validation effort has confirmed that the system is very accurate and stable, and many of the geophysical parameters have been validated. AIRS is in some cases more accurate than any other source and can therefore be difficult to validate, but this offers interesting new research opportunities. The applications for the AIRS products range from numerical weather prediction to atmospheric research - where the AIRS water vapor products near the surface and in the mid to upper troposphere will make it possible to characterize and model phenomena that are key for short-term atmospheric processes, such as weather patterns, to long-term processes, such as interannual cycles (e.g., El Nino) and climate change.

Effect of atmospheric refraction on radiative transfer in visible and near-infrared band: Model development, validation, and applications

NASA Astrophysics Data System (ADS)

Hu, Shuai; Gao, Tai-chang; Li, Hao; Liu, Lei; Liu, Xi-chuan; Zhang, Ting; Cheng, Tian-ji; Li, Wan-tong; Dai, Zhong-hua; Su, Xiaojian

2016-03-01

Refraction is an important factor influencing radiative transfer since it can modify the propagation trajectory and polarization states of lights; therefore, it is necessary to quantitively evaluate the effect of atmospheric refraction on radiative transfer process. To this end, a new atmospheric radiative transfer model including refraction process is proposed. The model accuracy is validated against benchmark results, literature results, and well-tested radiative transfer models such as discrete coordinate method and RT3/PolRadtran. The impact of atmospheric refraction on both polarized radiance and fluxes is discussed for pure Rayleigh scattering atmosphere, atmosphere with aerosol, and cloud. The results show that atmospheric refraction has a significant influence on both the radiance and polarization states of diffuse light, where the relative change of the radiance of reflected light and transmitted light due to refraction can achieve 6.3% and 7.4% for Rayleigh scattering atmosphere, 7.2% and 7.8% for atmosphere with aerosol, and 6.2% and 6.8% for cloudy atmosphere, respectively. The relative change of the degree of polarization ranges from near zero in the horizon to 9.5% near neutral points. The angular distribution pattern of the relative change of the radiance for atmosphere with aerosol and cloud is very similar to that for pure Rayleigh scattering case, where its magnitude decreases gradually with the increasing of zenith angle for reflected light; but for transmitted light, the variation characteristics is opposite. The impact of refraction is gradually enhanced with the increasing of solar zenith angles and the optical depth of aerosol and cloud. As the wavelength of incident light increases, the impact declines rapidly for Rayleigh scattering medium. The relative change of the fluxes due to refraction is most notable for Middle Latitude Winter profile (about 8.2043% and 7.3225% for the transmitted and reflected light, respectively, at 0.35 µm). With increasing the optical depth of aerosol, the influence of refraction on the fluxes is gradually enhanced. For cloudy atmosphere, the relative changes of the fluxes due to refraction are not very sensitive to the variation of cloud optical depth and effective radius of cloud drops.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seager, S.; Bains, W.; Hu, R.

Biosignature gas detection is one of the ultimate future goals for exoplanet atmosphere studies. We have created a framework for linking biosignature gas detectability to biomass estimates, including atmospheric photochemistry and biological thermodynamics. The new framework is intended to liberate predictive atmosphere models from requiring fixed, Earth-like biosignature gas source fluxes. New biosignature gases can be considered with a check that the biomass estimate is physically plausible. We have validated the models on terrestrial production of NO, H{sub 2}S, CH{sub 4}, CH{sub 3}Cl, and DMS. We have applied the models to propose NH{sub 3} as a biosignature gas on amore » 'cold Haber World', a planet with a N{sub 2}-H{sub 2} atmosphere, and to demonstrate why gases such as CH{sub 3}Cl must have too large of a biomass to be a plausible biosignature gas on planets with Earth or early-Earth-like atmospheres orbiting a Sun-like star. To construct the biomass models, we developed a functional classification of biosignature gases, and found that gases (such as CH{sub 4}, H{sub 2}S, and N{sub 2}O) produced from life that extracts energy from chemical potential energy gradients will always have false positives because geochemistry has the same gases to work with as life does, and gases (such as DMS and CH{sub 3}Cl) produced for secondary metabolic reasons are far less likely to have false positives but because of their highly specialized origin are more likely to be produced in small quantities. The biomass model estimates are valid to one or two orders of magnitude; the goal is an independent approach to testing whether a biosignature gas is plausible rather than a precise quantification of atmospheric biosignature gases and their corresponding biomasses.« less

Spectrally-Invariant Approximation Within Atmospheric Radiative Transfer

NASA Technical Reports Server (NTRS)

Marshak, A.; Knyazikhin, Y.; Chiu, J. C.; Wiscombe, W. J.

2011-01-01

Certain algebraic combinations of single scattering albedo and solar radiation reflected from, or transmitted through, vegetation canopies do not vary with wavelength. These "spectrally invariant relationships" are the consequence of wavelength independence of the extinction coefficient and scattering phase function in vegetation. In general, this wavelength independence does not hold in the atmosphere, but in clouddominated atmospheres the total extinction and total scattering phase function vary only weakly with wavelength. This paper identifies the atmospheric conditions under which the spectrally invariant approximation can accurately describe the extinction. and scattering properties of cloudy atmospheres. The validity of the assumptions and the accuracy of the approximation are tested with ID radiative transfer calculations using publicly available radiative transfer models: Discrete Ordinate Radiative Transfer (DISORT) and Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART). It is shown for cloudy atmospheres with cloud optical depth above 3, and for spectral intervals that exclude strong water vapor absorption, that the spectrally invariant relationships found in vegetation canopy radiative transfer are valid to better than 5%. The physics behind this phenomenon, its mathematical basis, and possible applications to remote sensing and climate are discussed.

Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) Model - An Unified Concept for Earthquake Precursors Validation

NASA Technical Reports Server (NTRS)

Pulinets, S.; Ouzounov, D.

2010-01-01

The paper presents a conception of complex multidisciplinary approach to the problem of clarification the nature of short-term earthquake precursors observed in atmosphere, atmospheric electricity and in ionosphere and magnetosphere. Our approach is based on the most fundamental principles of tectonics giving understanding that earthquake is an ultimate result of relative movement of tectonic plates and blocks of different sizes. Different kind of gases: methane, helium, hydrogen, and carbon dioxide leaking from the crust can serve as carrier gases for radon including underwater seismically active faults. Radon action on atmospheric gases is similar to the cosmic rays effects in upper layers of atmosphere: it is the air ionization and formation by ions the nucleus of water condensation. Condensation of water vapor is accompanied by the latent heat exhalation is the main cause for observing atmospheric thermal anomalies. Formation of large ion clusters changes the conductivity of boundary layer of atmosphere and parameters of the global electric circuit over the active tectonic faults. Variations of atmospheric electricity are the main source of ionospheric anomalies over seismically active areas. Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model can explain most of these events as a synergy between different ground surface, atmosphere and ionosphere processes and anomalous variations which are usually named as short-term earthquake precursors. A newly developed approach of Interdisciplinary Space-Terrestrial Framework (ISTF) can provide also a verification of these precursory processes in seismically active regions. The main outcome of this paper is the unified concept for systematic validation of different types of earthquake precursors united by physical basis in one common theory.

Assessing fossil fuel CO2 emissions in California using atmospheric observations and models

NASA Astrophysics Data System (ADS)

Graven, H.; Fischer, M. L.; Lueker, T.; Jeong, S.; Guilderson, T. P.; Keeling, R. F.; Bambha, R.; Brophy, K.; Callahan, W.; Cui, X.; Frankenberg, C.; Gurney, K. R.; LaFranchi, B. W.; Lehman, S. J.; Michelsen, H.; Miller, J. B.; Newman, S.; Paplawsky, W.; Parazoo, N. C.; Sloop, C.; Walker, S. J.

2018-06-01

Analysis systems incorporating atmospheric observations could provide a powerful tool for validating fossil fuel CO2 (ffCO2) emissions reported for individual regions, provided that fossil fuel sources can be separated from other CO2 sources or sinks and atmospheric transport can be accurately accounted for. We quantified ffCO2 by measuring radiocarbon (14C) in CO2, an accurate fossil-carbon tracer, at nine observation sites in California for three months in 2014–15. There is strong agreement between the measurements and ffCO2 simulated using a high-resolution atmospheric model and a spatiotemporally-resolved fossil fuel flux estimate. Inverse estimates of total in-state ffCO2 emissions are consistent with the California Air Resources Board’s reported ffCO2 emissions, providing tentative validation of California’s reported ffCO2 emissions in 2014–15. Continuing this prototype analysis system could provide critical independent evaluation of reported ffCO2 emissions and emissions reductions in California, and the system could be expanded to other, more data-poor regions.

Mathematical modeling of the growth and coarsening of ice particles in the context of high pressure shift freezing processes.

PubMed

Smith, N A S; Burlakov, V M; Ramos, Á M

2013-07-25

High pressure shift freezing (HPSF) has been proven more beneficial for ice crystal size and shape than traditional (at atmospheric pressure) freezing.1-3 A model for growth and coarsening of ice crystals inside a frozen food sample (either at atmospheric or high pressure) is developed, and some numerical experiments are given, with which the model is validated by using experimental data. To the best of our knowledge, this is the first model suited for freezing crystallization in the context of high pressure.

Scaling Characteristics of Mesoscale Wind Fields in the Lower Atmospheric Boundary Layer: Implications for Wind Energy

NASA Astrophysics Data System (ADS)

Kiliyanpilakkil, Velayudhan Praju

Atmospheric motions take place in spatial scales of sub-millimeters to few thousands of kilometers with temporal changes in the atmospheric variables occur in fractions of seconds to several years. Consequently, the variations in atmospheric kinetic energy associated with these atmospheric motions span over a broad spectrum of space and time. The mesoscale region acts as an energy transferring regime between the energy generating synoptic scale and the energy dissipating microscale. Therefore, the scaling characterizations of mesoscale wind fields are significant in the accurate estimation of the atmospheric energy budget. Moreover, the precise knowledge of the scaling characteristics of atmospheric mesoscale wind fields is important for the validation of the numerical models those focus on wind forecasting, dispersion, diffusion, horizontal transport, and optical turbulence. For these reasons, extensive studies have been conducted in the past to characterize the mesoscale wind fields. Nevertheless, the majority of these studies focused on near-surface and upper atmosphere mesoscale regimes. The present study attempt to identify the existence and to quantify the scaling of mesoscale wind fields in the lower atmospheric boundary layer (ABL; in the wind turbine layer) using wind observations from various research-grade instruments (e.g., sodars, anemometers). The scaling characteristics of the mesoscale wind speeds over diverse homogeneous flat terrains, conducted using structure function based analysis, revealed an altitudinal dependence of the scaling exponents. This altitudinal dependence of the wind speed scaling may be attributed to the buoyancy forcing. Subsequently, we use the framework of extended self-similarity (ESS) to characterize the observed scaling behavior. In the ESS framework, the relative scaling exponents of the mesoscale atmospheric boundary layer wind speed exhibit quasi-universal behavior; even far beyond the inertial range of turbulence (Delta t within 10 minutes to 6 hours range). The ESS framework based study is extended further to enquire its validity over complex terrain. This study, based on multiyear wind observations, demonstrate that the ESS holds for the lower ABL wind speed over the complex terrain as well. Another important inference from this study is that the ESS relative scaling exponents corresponding to the mesoscale wind speed closely matches the scaling characteristics of the inertial range turbulence, albeit not exactly identical. The current study proposes benchmark using ESS-based quasi-universal wind speed scaling characteristics in the ABL for the mesoscale modeling community. Using a state-of-the-art atmospheric mesoscale model in conjunction with different planetary boundary layer (PBL) parameterization schemes, multiple wind speed simulations have been conducted. This study reveals that the ESS scaling characteristics of the model simulated wind speed time series in the lower ABL vary significantly from their observational counterparts. The study demonstrate that the model simulated wind speed time series for the time intervals Delta t < 2 hours do not capture the ESS-based scaling characteristics. The detailed analysis of model simulations using different PBL schemes lead to the conclusion that there is a need for significant improvements in the turbulent closure parameterizations adapted in the new-generation atmospheric models. This study is unique as the ESS framework has never been reported or examined for the validation of PBL parameterizations.

Fluctuations of a Greenlandic tidewater glacier driven by changes in atmospheric forcing: observations and modelling of Kangiata Nunaata Sermia, 1859-present

NASA Astrophysics Data System (ADS)

Lea, J. M.; Mair, D. W. F.; Nick, F. M.; Rea, B. R.; van As, D.; Morlighem, M.; Nienow, P. W.; Weidick, A.

2014-11-01

Many tidewater glaciers in Greenland are known to have undergone significant retreat during the last century following their Little Ice Age maxima. Where it is possible to reconstruct glacier change over this period, they provide excellent records for comparison to climate records, as well as calibration/validation for numerical models. These glacier change records therefore allow for tests of numerical models that seek to simulate tidewater glacier behaviour over multi-decadal to centennial timescales. Here we present a detailed record of behaviour from Kangiata Nunaata Sermia (KNS), SW Greenland, between 1859 and 2012, and compare it against available oceanographic and atmospheric temperature data between 1871 and 2012. We also use these records to evaluate the ability of a well-established one-dimensional flow-band model to replicate behaviour for the observation period. The record of terminus change demonstrates that KNS has advanced/retreated in phase with atmosphere and ocean climate anomalies averaged over multi-annual to decadal timescales. Results from an ensemble of model runs demonstrate that observed dynamics can be replicated. Model runs that provide a reasonable match to observations always require a significant atmospheric forcing component, but do not necessarily require an oceanic forcing component. Although the importance of oceanic forcing cannot be discounted, these results demonstrate that changes in atmospheric forcing are likely to be a primary driver of the terminus fluctuations of KNS from 1859 to 2012. We propose that the detail and length of the record presented makes KNS an ideal site for model validation exercises investigating links between climate, calving rates, and tidewater glacier dynamics.

Field validation of a free-agent cellular automata model of fire spread with fire–atmosphere coupling

Treesearch

Gary Achtemeier

2012-01-01

A cellular automata fire model represents ‘elements’ of fire by autonomous agents. A few simple algebraic expressions substituted for complex physical and meteorological processes and solved iteratively yield simulations for ‘super-diffusive’ fire spread and coupled surface-layer (2-m) fire–atmosphere processes. Pressure anomalies, which are integrals of the thermal...

Application of aerosol speciation data as an in situ dust proxy for validation of the Dust Regional Atmospheric Model (DREAM)

NASA Astrophysics Data System (ADS)

Shaw, Patrick

The Dust REgional Atmospheric Model (DREAM) predicts concentrations of mineral dust aerosols in time and space, but validation is challenging with current in situ particulate matter (PM) concentration measurements. Measured levels of ambient PM often contain anthropogenic components as well as windblown mineral dust. In this study, two approaches to model validation were performed with data from preexisting air quality monitoring networks: using hourly concentrations of total PM with aerodynamic diameter less than 2.5 μm (PM 2.5); and using a daily averaged speciation-derived soil component. Validation analyses were performed for point locations within the cities of El Paso (TX), Austin (TX), Phoenix (AZ), Salt Lake City (UT) and Bakersfield (CA) for most of 2006. Hourly modeled PM 2.5 did not validate at all with hourly observations among the sites (combined R < 0.00, N = 24,302 hourly values). Aerosol chemical speciation data distinguished between mineral (soil) dust from anthropogenic ambient PM. As expected, statistically significant improvements in correlation among all stations (combined R = 0.16, N = 343 daily values) were found when the soil component alone was used to validate DREAM. The validation biases that result from anthropogenic aerosols were also reduced using the soil component. This is seen in the reduction of the root mean square error between hourly in situ versus hourly modeled (RMSE hourly = 18.6 μg m -3) and 24-h in situ speciation values versus daily averaged observed (RMSE soil = 12.0 μg m -3). However, the lack of a total reduction in RMSE indicates there is still room for improvement in the model. While the soil component is the theoretical proxy of choice for a dust transport model, the current sparse and infrequent sampling is not ideal for routine hourly air quality forecast validation.

The Space Weather Modeling Framework (SWMF): Models and Validation

NASA Astrophysics Data System (ADS)

Gombosi, Tamas; Toth, Gabor; Sokolov, Igor; de Zeeuw, Darren; van der Holst, Bart; Ridley, Aaron; Manchester, Ward, IV

In the last decade our group at the Center for Space Environment Modeling (CSEM) has developed the Space Weather Modeling Framework (SWMF) that efficiently couples together different models describing the interacting regions of the space environment. Many of these domain models (such as the global solar corona, the inner heliosphere or the global magneto-sphere) are based on MHD and are represented by our multiphysics code, BATS-R-US. SWMF is a powerful tool for coupling regional models describing the space environment from the solar photosphere to the bottom of the ionosphere. Presently, SWMF contains over a dozen components: the solar corona (SC), eruptive event generator (EE), inner heliosphere (IE), outer heliosphere (OH), solar energetic particles (SE), global magnetosphere (GM), inner magnetosphere (IM), radiation belts (RB), plasmasphere (PS), ionospheric electrodynamics (IE), polar wind (PW), upper atmosphere (UA) and lower atmosphere (LA). This talk will present an overview of SWMF, new results obtained with improved physics as well as some validation studies.

High-resolution computational algorithms for simulating offshore wind turbines and farms: Model development and validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calderer, Antoni; Yang, Xiaolei; Angelidis, Dionysios

2015-10-30

The present project involves the development of modeling and analysis design tools for assessing offshore wind turbine technologies. The computational tools developed herein are able to resolve the effects of the coupled interaction of atmospheric turbulence and ocean waves on aerodynamic performance and structural stability and reliability of offshore wind turbines and farms. Laboratory scale experiments have been carried out to derive data sets for validating the computational models.

Improved atmospheric 3D BSDF model in earthlike exoplanet using ray-tracing based method

NASA Astrophysics Data System (ADS)

Ryu, Dongok; Kim, Sug-Whan; Seong, Sehyun

2012-10-01

The studies on planetary radiative transfer computation have become important elements to disk-averaged spectral characterization of potential exoplanets. In this paper, we report an improved ray-tracing based atmospheric simulation model as a part of 3-D earth-like planet model with 3 principle sub-components i.e. land, sea and atmosphere. Any changes in ray paths and their characteristics such as radiative power and direction are computed as they experience reflection, refraction, transmission, absorption and scattering. Improved atmospheric BSDF algorithms uses Q.Liu's combined Rayleigh and aerosol Henrey-Greenstein scattering phase function. The input cloud-free atmosphere model consists of 48 layers with vertical absorption profiles and a scattering layer with their input characteristics using the GIOVANNI database. Total Solar Irradiance data are obtained from Solar Radiation and Climate Experiment (SORCE) mission. Using aerosol scattering computation, we first tested the atmospheric scattering effects with imaging simulation with HRIV, EPOXI. Then we examined the computational validity of atmospheric model with the measurements of global, direct and diffuse radiation taken from NREL(National Renewable Energy Laboratory)s pyranometers and pyrheliometers on a ground station for cases of single incident angle and for simultaneous multiple incident angles of the solar beam.

Towards TCCON Tropics: Assessment and Measurements of Carbon and its Climate Impacts in Southeast Asia (T3AM C2lImA)

NASA Astrophysics Data System (ADS)

Morino, I.; Velazco, V. A.; Schwandner, F. M.; Macatangay, R. C.; Griffith, D. W. T.

2015-12-01

TCCON (Total Carbon Column Observing Network) measurements of CO2 and CH4 have been and are currently used extensively and globally for satellite validation, for comparison with atmospheric chemistry models and to study atmosphere-biosphere exchanges of carbon. With the global effort to cap greenhouse gas emissions, TCCON has become vital for validating satellite-based greenhouse gas data from past, current and future missions like Japanese GOSAT (Greenhouse Gas Observing SATellite) and GOSAT-2, NASA's OCO-2 (Orbiting Carbon Observatory-2) and OCO-3, ESA's Carbon Monitoring Satellite (CarbonSat), Chinese TanSat, and others. The lack of reliable validation data for the satellite-based greenhouse gas observing missions in the tropical regions is a common limitation in global carbon-cycle modeling studies that have a tropical component. The international CO2 modeling community have specified a requirement for "expansion of the CO2 observation network within the tropics" to reduce uncertainties in regional estimates of CO2 sources and sinks using atmospheric transport models. A TCCON site in the western tropical Pacific is a logical next step in obtaining additional knowledge that would greatly contribute to the understanding of the Earth's atmosphere and better constraining a major tropical region experiencing tremendous economic and population growth. Here, we present a complete site assessment for a possible TCCON site in the Philippines and our decision on the site where a new TCCON FTS will be installed. This site assessment was conducted in cooperation with the Energy Development Corporation (EDC, Philippines), National Institute for Environmental Studies (NIES, Japan), University of Wollongong (UoW, Australia), NASA's Jet Propulsion Laboratory (JPL), the University of the Philippines (UP-IESM), the TCCON science team, and the GOSAT-2 science team.

AIRS Retrieval Validation During the EAQUATE

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Smith, William L.; Cuomo, Vincenzo; Taylor, Jonathan P.; Barnet, Christopher D.; DiGirolamo, Paolo; Pappalardo, Gelsomina; Larar, Allen M.; Liu, Xu; Newman, Stuart M.

2006-01-01

Atmospheric and surface thermodynamic parameters retrieved with advanced hyperspectral remote sensors of Earth observing satellites are critical for weather prediction and scientific research. The retrieval algorithms and retrieved parameters from satellite sounders must be validated to demonstrate the capability and accuracy of both observation and data processing systems. The European AQUA Thermodynamic Experiment (EAQUATE) was conducted mainly for validation of the Atmospheric InfraRed Sounder (AIRS) on the AQUA satellite, but also for assessment of validation systems of both ground-based and aircraft-based instruments which will be used for other satellite systems such as the Infrared Atmospheric Sounding Interferometer (IASI) on the European MetOp satellite, the Cross-track Infrared Sounder (CrIS) from the NPOESS Preparatory Project and the following NPOESS series of satellites. Detailed inter-comparisons were conducted and presented using different retrieval methodologies: measurements from airborne ultraspectral Fourier transform spectrometers, aircraft in-situ instruments, dedicated dropsondes and radiosondes, and ground based Raman Lidar, as well as from the European Center for Medium range Weather Forecasting (ECMWF) modeled thermal structures. The results of this study not only illustrate the quality of the measurements and retrieval products but also demonstrate the capability of these validation systems which are put in place to validate current and future hyperspectral sounding instruments and their scientific products.

A Multiple Scattering Polarized Radiative Transfer Model: Application to HD 189733b

NASA Astrophysics Data System (ADS)

Kopparla, Pushkar; Natraj, Vijay; Zhang, Xi; Swain, Mark R.; Wiktorowicz, Sloane J.; Yung, Yuk L.

2016-01-01

We present a multiple scattering vector radiative transfer model that produces disk integrated, full phase polarized light curves for reflected light from an exoplanetary atmosphere. We validate our model against results from published analytical and computational models and discuss a small number of cases relevant to the existing and possible near-future observations of the exoplanet HD 189733b. HD 189733b is arguably the most well observed exoplanet to date and the only exoplanet to be observed in polarized light, yet it is debated if the planet’s atmosphere is cloudy or clear. We model reflected light from clear atmospheres with Rayleigh scattering, and cloudy or hazy atmospheres with Mie and fractal aggregate particles. We show that clear and cloudy atmospheres have large differences in polarized light as compared to simple flux measurements, though existing observations are insufficient to make this distinction. Futhermore, we show that atmospheres that are spatially inhomogeneous, such as being partially covered by clouds or hazes, exhibit larger contrasts in polarized light when compared to clear atmospheres. This effect can potentially be used to identify patchy clouds in exoplanets. Given a set of full phase polarimetric measurements, this model can constrain the geometric albedo, properties of scattering particles in the atmosphere, and the longitude of the ascending node of the orbit. The model is used to interpret new polarimetric observations of HD 189733b in a companion paper.

Retrievals with the Infrared Atmospheric Sounding Interferometer

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schlussel, Peter; Strow, L. Larrabee; Calbet, Xavier; Mango, Stephen A.

2007-01-01

The Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite was launched on October 19, 2006. The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25/cm and a spectral coverage from 645 to 2760/cm. Ultraspectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations during the JAIVEx are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated.

Carbon dioxide electron cooling rates in the atmospheres of Mars and Venus

NASA Astrophysics Data System (ADS)

Campbell, L.; Brunger, M. J.; Rescigno, T. N.

2008-08-01

The cooling of electrons in collisions with carbon dioxide in the atmospheres of Venus and Mars is investigated. Calculations are performed with both previously accepted electron energy transfer rates and with new ones determined using more recent theoretical and experimental cross sections for electron impact on CO2. Emulation of a previous model for Venus confirms the validity of the current model and shows that use of the updated cross sections leads to cooling rates that are lower by one third. Application of the same model to the atmosphere of Mars gives more than double the previous cooling rates at altitudes where the electron temperature is very low.

Numerical Modeling Studies of Wake Vortices: Real Case Simulations

NASA Technical Reports Server (NTRS)

Shen, Shao-Hua; Ding, Feng; Han, Jongil; Lin, Yuh-Lang; Arya, S. Pal; Proctor, Fred H.

1999-01-01

A three-dimensional large-eddy simulation model, TASS, is used to simulate the behavior of aircraft wake vortices in a real atmosphere. The purpose for this study is to validate the use of TASS for simulating the decay and transport of wake vortices. Three simulations are performed and the results are compared with the observed data from the 1994-1995 Memphis field experiments. The selected cases have an atmospheric environment of weak turbulence and stable stratification. The model simulations are initialized with appropriate meteorological conditions and a post roll-up vortex system. The behavior of wake vortices as they descend within the atmospheric boundary layer and interact with the ground is discussed.

Validation of Infrared Azimuthal Model as Applied to GOES Data Over the ARM SGP

NASA Technical Reports Server (NTRS)

Gambheer, Arvind V.; Doelling, David R.; Spangenberg, Douglas A.; Minnis, Patrick

2004-01-01

The goal of this research is to identify and reduce the GOES-8 IR temperature biases, induced by a fixed geostationary position, during the course of a day. In this study, the same CERES LW window channel model is applied to GOES-8 IR temperatures during clear days over the Atmospheric Radiation Measurement-Southern Great Plains Central Facility (SCF). The model-adjusted and observed IR temperatures are compared with topof- the-atmosphere (TOA) estimated temperatures derived from a radiative transfer algorithm based on the atmospheric profile and surface radiometer measurements. This algorithm can then be incorporated to derive more accurate Ts from real-time satellite operational products.

The model SIRANE for atmospheric urban pollutant dispersion. PART III: Validation against NO2 yearly concentration measurements in a large urban agglomeration

NASA Astrophysics Data System (ADS)

Soulhac, L.; Nguyen, C. V.; Volta, P.; Salizzoni, P.

2017-10-01

We present a validation study of an updated version of the SIRANE model, whose results have been systematically compared to concentrations of nitrogen dioxide collected over the whole urban agglomeration of Lyon. We model atmospheric dispersion of nitrogen oxides emitted by road traffic, industries and domestic heating. The meteorological wind field is computed by a pre-processor using data collected at a ground level monitoring station. Model results are compared with hourly concentrations measured at 15 monitoring stations over the whole year (2008). Further 75 passive diffusion samplers were used during 3 periods of 2 weeks to get a detailed spatial distribution over the west part of the city. An analysis of the model results depending on the variability of the meteorological input allows us to identify the causes for peculiar bad performances of the model and to identify possible improvements of the parameterisations implemented in it.

Command generator tracker based direct model reference adaptive tracking guidance for Mars atmospheric entry

NASA Astrophysics Data System (ADS)

Li, Shuang; Peng, Yuming

2012-01-01

In order to accurately deliver an entry vehicle through the Martian atmosphere to the prescribed parachute deployment point, active Mars entry guidance is essential. This paper addresses the issue of Mars atmospheric entry guidance using the command generator tracker (CGT) based direct model reference adaptive control to reduce the adverse effect of the bounded uncertainties on atmospheric density and aerodynamic coefficients. Firstly, the nominal drag acceleration profile meeting a variety of constraints is planned off-line in the longitudinal plane as the reference model to track. Then, the CGT based direct model reference adaptive controller and the feed-forward compensator are designed to robustly track the aforementioned reference drag acceleration profile and to effectively reduce the downrange error. Afterwards, the heading alignment logic is adopted in the lateral plane to reduce the crossrange error. Finally, the validity of the guidance algorithm proposed in this paper is confirmed by Monte Carlo simulation analysis.

Caracterisation, modelisation et validation du transfert radiatif d'atmospheres non standard; impact sur les corrections atmospheriques d'images de teledetection

NASA Astrophysics Data System (ADS)

Zidane, Shems

This study is based on data acquired with an airborne multi-altitude sensor on July 2004 during a nonstandard atmospheric event in the region of Saint-Jean-sur-Richelieu, Quebec. By non-standard atmospheric event we mean an aerosol atmosphere that does not obey the typical monotonic, scale height variation employed in virtually all atmospheric correction codes. The surfaces imaged during this field campaign included a diverse variety of targets : agricultural land, water bodies, urban areas and forests. The multi-altitude approach employed in this campaign allowed us to better understand the altitude dependent influence of the atmosphere over the array of ground targets and thus to better characterize the perturbation induced by a non-standard (smoke) plume. The transformation of the apparent radiance at 3 different altitudes into apparent reflectance and the insertion of the plume optics into an atmospheric correction model permitted an atmospheric correction of the apparent reflectance at the two higher altitudes. The results showed consistency with the apparent validation reflectances derived from the lowest altitude radiances. This approach effectively confirmed the accuracy of our non-standard atmospheric correction approach. This test was particularly relevant at the highest altitude of 3.17 km : the apparent reflectances at this altitude were above most of the plume and therefore represented a good test of our ability to adequately correct for the influence of the perturbation. Standard atmospheric disturbances are obviously taken into account in most atmospheric correction models, but these are based on monotonically decreasing aerosol variations with increasing altitude. When the atmospheric radiation is affected by a plume or a local, non-standard pollution event, one must adapt the existing models to the radiative transfer constraints of the local perturbation and to the reality of the measurable parameters available for ingestion into the model. The main inputs of this study were those normally used in an atmospheric correction : apparent at-sensor radiance and the aerosol optical depth (AOD) acquired using ground-based sunphotometry. The procedure we employed made use of a standard atmospheric correction code (CAM5S, for Canadian Modified 5S, which comes from the 5S radiative transfer model in the visible and near infrared) : however, we also used other parameters and data to adapt and correctly model the special atmospheric situation which affected the multi-altitude images acquired during the St. Jean field campaign. We then developed a modeling protocol for these atmospheric perturbations where auxiliary data was employed to complement our main data-set. This allowed for the development of a robust and simple methodology adapted to this atmospheric situation. The auxiliary data, i.e. meteorological data, LIDAR profiles, various satellite images and sun photometer retrievals of the scattering phase function, were sufficient to accurately model the observed plume in terms of a unusual, vertical distribution. This distribution was transformed into an aerosol optical depth profile that replaced the standard aerosol optical depth profile employed in the CAM5S atmospheric correction model. Based on this model, a comparison between the apparent ground reflectances obtained after atmospheric corrections and validation values of R*(0) obtained from the lowest altitude data showed that the error between the two was less than 0.01 rms. This correction was shown to be a significantly better estimation of the surface reflectance than that obtained using the atmospheric correction model. Significant differences were nevertheless observed in the non-standard solution : these were mainly caused by the difficulties brought about by the acquisition conditions, significant disparities attributable to inconsistencies in the co-sampling / co-registration of different targets from three different altitudes, and possibly modeling errors and / or calibration. There is accordingly room for improvement in our approach to dealing with such conditions. The modeling and forecasting of such a disturbance is explicitly described in this document: our goal in so doing is to permit the establishment of a better protocol for the acquisition of more suitable supporting data. The originality of this study stems from a new approach for incorporating a plume structure into an operational atmospheric correction model and then demonstrating that the approach was a significant improvement over an approach that ignored the perturbations in the vertical profile while employing the correct overall AOD. The profile model we employed was simple and robust but captured sufficient plume detail to achieve significant improvements in atmospheric correction accuracy. The overall process of addressing all the problems encountered in the analysis of our aerosol perturbation helped us to build an appropriate methodology for characterizing such events based on data availability, distributed freely and accessible to the scientific community. This makes our study adaptable and exportable to other types of non-standard atmospheric events. Keywords : non-standard atmospheric perturbation, multi-altitude apparent radiances, smoke plume, Gaussian plume modelization, radiance fit, AOD, CASI

ISSARS Aerosol Database : an Incorporation of Atmospheric Particles into a Universal Tool to Simulate Remote Sensing Instruments

NASA Technical Reports Server (NTRS)

Goetz, Michael B.

2011-01-01

The Instrument Simulator Suite for Atmospheric Remote Sensing (ISSARS) entered its third and final year of development with an overall goal of providing a unified tool to simulate active and passive space borne atmospheric remote sensing instruments. These simulations focus on the atmosphere ranging from UV to microwaves. ISSARS handles all assumptions and uses various models on scattering and microphysics to fill the gaps left unspecified by the atmospheric models to create each instrument's measurements. This will help benefit mission design and reduce mission cost, create efficient implementation of multi-instrument/platform Observing System Simulation Experiments (OSSE), and improve existing models as well as new advanced models in development. In this effort, various aerosol particles are incorporated into the system, and a simulation of input wavelength and spectral refractive indices related to each spherical test particle(s) generate its scattering properties and phase functions. These atmospheric particles being integrated into the system comprise the ones observed by the Multi-angle Imaging SpectroRadiometer(MISR) and by the Multiangle SpectroPolarimetric Imager(MSPI). In addition, a complex scattering database generated by Prof. Ping Yang (Texas A&M) is also incorporated into this aerosol database. Future development with a radiative transfer code will generate a series of results that can be validated with results obtained by the MISR and MSPI instruments; nevertheless, test cases are simulated to determine the validity of various plugin libraries used to determine or gather the scattering properties of particles studied by MISR and MSPI, or within the Single-scattering properties of tri-axial ellipsoidal mineral dust particles database created by Prof. Ping Yang.

Linear and nonlinear acoustic wave propagation in the atmosphere

NASA Technical Reports Server (NTRS)

Hariharan, S. I.; Yu, Ping

1988-01-01

The investigation of the acoustic wave propagation theory and numerical implementation for the situation of an isothermal atmosphere is described. A one-dimensional model to validate an asymptotic theory and a 3-D situation to relate to a realistic situation are considered. In addition, nonlinear wave propagation and the numerical treatment are included. It is known that the gravitational effects play a crucial role in the low frequency acoustic wave propagation. They propagate large distances and, as such, the numerical treatment of those problems become difficult in terms of posing boundary conditions which are valid for all frequencies.

Inversion Schemes to Retrieve Atmospheric and Oceanic Parameters from SeaWiFS Data

NASA Technical Reports Server (NTRS)

Deschamps, P.-Y.; Frouin, R.

1997-01-01

The investigation focuses on two key issues in satellite ocean color remote sensing, namely the presence of whitecaps on the sea surface and the validity of the aerosol models selected for the atmospheric correction of SeaWiFS data. Experiments were designed and conducted at the Scripps Institution of Oceanography to measure the optical properties of whitecaps and to study the aerosol optical properties in a typical mid-latitude coastal environment. CIMEL Electronique sunphotometers, now integrated in the AERONET network, were also deployed permanently in Bermuda and in Lanai, calibration/validation sites for SeaWiFS and MODIS. Original results were obtained on the spectral reflectance of whitecaps and on the choice of aerosol models for atmospheric correction schemes and the type of measurements that should be made to verify those schemes. Bio-optical algorithms to remotely sense primary productivity from space were also evaluated, as well as current algorithms to estimate PAR at the earth's surface.

AN ANALYTIC RADIATIVE-CONVECTIVE MODEL FOR PLANETARY ATMOSPHERES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Tyler D.; Catling, David C., E-mail: robinson@astro.washington.edu

2012-09-20

We present an analytic one-dimensional radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power-law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric-pressure-temperature profile, as well as expressions formore » the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries; (2) worlds with some attenuation of sunlight throughout the atmosphere, which we show can produce either shallow or deep radiative-convective boundaries, depending on the strength of sunlight attenuation; and (3) strongly irradiated giant planets (including hot Jupiters), where we explore the conditions under which these worlds acquire detached convective regions in their mid-tropospheres. Finally, we validate our model and demonstrate its utility through comparisons to the average observed thermal structure of Venus, Jupiter, and Titan, and by comparing computed flux profiles to more complex models.« less

High resolution infrared datasets useful for validating stratospheric models

NASA Technical Reports Server (NTRS)

Rinsland, Curtis P.

1992-01-01

An important objective of the High Speed Research Program (HSRP) is to support research in the atmospheric sciences that will improve the basic understanding of the circulation and chemistry of the stratosphere and lead to an interim assessment of the impact of a projected fleet of High Speed Civil Transports (HSCT's) on the stratosphere. As part of this work, critical comparisons between models and existing high quality measurements are planned. These comparisons will be used to test the reliability of current atmospheric chemistry models. Two suitable sets of high resolution infrared measurements are discussed.

Validation Test Report for the Navy Coastal Ocean Model Four-Dimensional Variational Assimilation (NCOM 4DVAR) System Version 1.0

DTIC Science & Technology

2015-09-14

three hours) and surface atmospheric forcing, such as wind  stress ,  atmospheric  pressure,  and  surface  heat   flux  is  provided  by  the  0.5⁰ NOGAPS...iTS A uthor/ COW S. Smti h ~~ R £ {;/-; ;;~-.::tt.-4’_ ~ Prevulusly <~flPl"<lH·d a’ 1 ~- 1::3 1 -0f,RI S..""C~O.l Head Dan c1n lr~~ ~v..:_~.t ~ )All...Global  Environmental  Model  (NAVGEM).  In most cases, atmospheric model wind  stresses ,  radiation  fluxes, and atmospheric pressure,  temperature

Modelling and validation land-atmospheric heat fluxes by using classical surface parameters over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Ma, W.; Ma, Y.; Hu, Z.; Zhong, L.

2017-12-01

In this study, a land-atmosphere model was initialized by ingesting AMSR-E products, and the results were compared with the default model configuration and with in situ long-term CAMP/Tibet observations. Firstly our field observation sites will be introduced based on ITPCAS (Institute of Tibetan Plateau Research, Chinese Academy of Sciences). Then, a land-atmosphere model was initialized by ingesting AMSR-E products, and the results were compared with the default model configuration and with in situ long-term CAMP/Tibet observations. The differences between the AMSR-E initialized model runs with the default model configuration and in situ data showed an apparent inconsistency in the model-simulated land surface heat fluxes. The results showed that the soil moisture was sensitive to the specific model configuration. To evaluate and verify the model stability, a long-term modeling study with AMSR-E soil moisture data ingestion was performed. Based on test simulations, AMSR-E data were assimilated into an atmospheric model for July and August 2007. The results showed that the land surface fluxes agreed well with both the in situ data and the results of the default model configuration. Therefore, the simulation can be used to retrieve land surface heat fluxes from an atmospheric model over the Tibetan Plateau.

Beam wandering statistics of twin thin laser beam propagation under generalized atmospheric conditions.

PubMed

Pérez, Darío G; Funes, Gustavo

2012-12-03

Under the Geometrics Optics approximation is possible to estimate the covariance between the displacements of two thin beams after they have propagated through a turbulent medium. Previous works have concentrated in long propagation distances to provide models for the wandering statistics. These models are useful when the separation between beams is smaller than the propagation path-regardless of the characteristics scales of the turbulence. In this work we give a complete model for these covariances, behavior introducing absolute limits to the validity of former approximations. Moreover, these generalizations are established for non-Kolmogorov atmospheric models.

Modeling Io's Sublimation-Driven Atmosphere: Gas Dynamics and Radiation Emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, Andrew C.; Goldstein, David B.; Varghese, Philip L.

2008-12-31

Io's sublimation-driven atmosphere is modeled using the direct simulation Monte Carlo method. These rarefied gas dynamics simulations improve upon earlier models by using a three-dimensional domain encompassing the entire planet computed in parallel. The effects of plasma impact heating, planetary rotation, and inhomogeneous surface frost are investigated. Circumplanetary flow is predicted to develop from the warm subsolar region toward the colder night-side. The non-equilibrium thermal structure of the atmosphere, including vibrational and rotational temperatures, is also presented. Io's rotation leads to an asymmetric surface temperature distribution which is found to strengthen circumplanetary flow near the dusk terminator. Plasma heating ismore » found to significantly inflate the atmosphere on both day- and night-sides. The plasma energy flux also causes high temperatures at high altitudes but permits relatively cooler temperatures at low altitudes near the dense subsolar point due to plasma energy depletion. To validate the atmospheric model, a radiative transfer model was developed utilizing the backward Monte Carlo method. The model allows the calculation of the atmospheric radiation from emitting/absorbing and scattering gas using an arbitrary scattering law and an arbitrary surface reflectivity. The model calculates the spectra in the {nu}{sub 2} vibrational band of SO{sub 2} which are then compared to the observational data.« less

Detailed Modeling and Analysis of the CPFM Dataset

NASA Technical Reports Server (NTRS)

Swartz, William H.; Lloyd, Steven A.; DeMajistre, Robert

2004-01-01

A quantitative understanding of photolysis rate coefficients (or "j-values") is essential to determining the photochemical reaction rates that define ozone loss and other crucial processes in the atmosphere. j-Values can be calculated with radiative transfer models, derived from actinic flux observations, or inferred from trace gas measurements. The principal objective of this study is to cross-validate j-values from the Composition and Photodissociative Flux Measurement (CPFM) instrument during the Photochemistry of Ozone Loss in the Arctic Region In Summer (POLARIS) and SAGE I11 Ozone Loss and Validation Experiment (SOLVE) field campaigns with model calculations and other measurements and to use this detailed analysis to improve our ability to determine j-values. Another objective is to analyze the spectral flux from the CPFM (not just the j-values) and, using a multi-wavelength/multi-species spectral fitting technique, determine atmospheric composition.

Uncertainty in Earth System Models: Benchmarks for Ocean Model Performance and Validation

NASA Astrophysics Data System (ADS)

Ogunro, O. O.; Elliott, S.; Collier, N.; Wingenter, O. W.; Deal, C.; Fu, W.; Hoffman, F. M.

2017-12-01

The mean ocean CO2 sink is a major component of the global carbon budget, with marine reservoirs holding about fifty times more carbon than the atmosphere. Phytoplankton play a significant role in the net carbon sink through photosynthesis and drawdown, such that about a quarter of anthropogenic CO2 emissions end up in the ocean. Biology greatly increases the efficiency of marine environments in CO2 uptake and ultimately reduces the impact of the persistent rise in atmospheric concentrations. However, a number of challenges remain in appropriate representation of marine biogeochemical processes in Earth System Models (ESM). These threaten to undermine the community effort to quantify seasonal to multidecadal variability in ocean uptake of atmospheric CO2. In a bid to improve analyses of marine contributions to climate-carbon cycle feedbacks, we have developed new analysis methods and biogeochemistry metrics as part of the International Ocean Model Benchmarking (IOMB) effort. Our intent is to meet the growing diagnostic and benchmarking needs of ocean biogeochemistry models. The resulting software package has been employed to validate DOE ocean biogeochemistry results by comparison with observational datasets. Several other international ocean models contributing results to the fifth phase of the Coupled Model Intercomparison Project (CMIP5) were analyzed simultaneously. Our comparisons suggest that the biogeochemical processes determining CO2 entry into the global ocean are not well represented in most ESMs. Polar regions continue to show notable biases in many critical biogeochemical and physical oceanographic variables. Some of these disparities could have first order impacts on the conversion of atmospheric CO2 to organic carbon. In addition, single forcing simulations show that the current ocean state can be partly explained by the uptake of anthropogenic emissions. Combined effects of two or more of these forcings on ocean biogeochemical cycles and ecosystems are challenging to predict since additive or antagonistic effects may occur. A benchmarking tool for accurate assessment and validation of marine biogeochemical outputs will be indispensable as the model community continues to improve ESM developments. It will provide a first order tool in understanding climate-carbon cycle feedbacks.

OCCIMA: Optical Channel Characterization in Maritime Atmospheres

NASA Astrophysics Data System (ADS)

Hammel, Steve; Tsintikidis, Dimitri; deGrassie, John; Reinhardt, Colin; McBryde, Kevin; Hallenborg, Eric; Wayne, David; Gibson, Kristofor; Cauble, Galen; Ascencio, Ana; Rudiger, Joshua

2015-05-01

The Navy is actively developing diverse optical application areas, including high-energy laser weapons and free- space optical communications, which depend on an accurate and timely knowledge of the state of the atmospheric channel. The Optical Channel Characterization in Maritime Atmospheres (OCCIMA) project is a comprehensive program to coalesce and extend the current capability to characterize the maritime atmosphere for all optical and infrared wavelengths. The program goal is the development of a unified and validated analysis toolbox. The foundational design for this program coordinates the development of sensors, measurement protocols, analytical models, and basic physics necessary to fulfill this goal.

Verification of land-atmosphere coupling in forecast models, reanalyses and land surface models using flux site observations.

PubMed

Dirmeyer, Paul A; Chen, Liang; Wu, Jiexia; Shin, Chul-Su; Huang, Bohua; Cash, Benjamin A; Bosilovich, Michael G; Mahanama, Sarith; Koster, Randal D; Santanello, Joseph A; Ek, Michael B; Balsamo, Gianpaolo; Dutra, Emanuel; Lawrence, D M

2018-02-01

We confront four model systems in three configurations (LSM, LSM+GCM, and reanalysis) with global flux tower observations to validate states, surface fluxes, and coupling indices between land and atmosphere. Models clearly under-represent the feedback of surface fluxes on boundary layer properties (the atmospheric leg of land-atmosphere coupling), and may over-represent the connection between soil moisture and surface fluxes (the terrestrial leg). Models generally under-represent spatial and temporal variability relative to observations, which is at least partially an artifact of the differences in spatial scale between model grid boxes and flux tower footprints. All models bias high in near-surface humidity and downward shortwave radiation, struggle to represent precipitation accurately, and show serious problems in reproducing surface albedos. These errors create challenges for models to partition surface energy properly and errors are traceable through the surface energy and water cycles. The spatial distribution of the amplitude and phase of annual cycles (first harmonic) are generally well reproduced, but the biases in means tend to reflect in these amplitudes. Interannual variability is also a challenge for models to reproduce. Our analysis illuminates targets for coupled land-atmosphere model development, as well as the value of long-term globally-distributed observational monitoring.

Containment Sodium Chemistry Models in MELCOR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louie, David; Humphries, Larry L.; Denman, Matthew R

To meet regulatory needs for sodium fast reactors’ future development, including licensing requirements, Sandia National Laboratories is modernizing MELCOR, a severe accident analysis computer code developed for the U.S. Nuclear Regulatory Commission (NRC). Specifically, Sandia is modernizing MELCOR to include the capability to model sodium reactors. However, Sandia’s modernization effort primarily focuses on the containment response aspects of the sodium reactor accidents. Sandia began modernizing MELCOR in 2013 to allow a sodium coolant, rather than water, for conventional light water reactors. In the past three years, Sandia has been implementing the sodium chemistry containment models in CONTAIN-LMR, a legacy NRCmore » code, into MELCOR. These chemistry models include spray fire, pool fire and atmosphere chemistry models. Only the first two chemistry models have been implemented though it is intended to implement all these models into MELCOR. A new package called “NAC” has been created to manage the sodium chemistry model more efficiently. In 2017 Sandia began validating the implemented models in MELCOR by simulating available experiments. The CONTAIN-LMR sodium models include sodium atmosphere chemistry and sodium-concrete interaction models. This paper presents sodium property models, the implemented models, implementation issues, and a path towards validation against existing experimental data.« less

Linearized Flux Evolution (LiFE): A technique for rapidly adapting fluxes from full-physics radiative transfer models

NASA Astrophysics Data System (ADS)

Robinson, Tyler D.; Crisp, David

2018-05-01

Solar and thermal radiation are critical aspects of planetary climate, with gradients in radiative energy fluxes driving heating and cooling. Climate models require that radiative transfer tools be versatile, computationally efficient, and accurate. Here, we describe a technique that uses an accurate full-physics radiative transfer model to generate a set of atmospheric radiative quantities which can be used to linearly adapt radiative flux profiles to changes in the atmospheric and surface state-the Linearized Flux Evolution (LiFE) approach. These radiative quantities describe how each model layer in a plane-parallel atmosphere reflects and transmits light, as well as how the layer generates diffuse radiation by thermal emission and by scattering light from the direct solar beam. By computing derivatives of these layer radiative properties with respect to dynamic elements of the atmospheric state, we can then efficiently adapt the flux profiles computed by the full-physics model to new atmospheric states. We validate the LiFE approach, and then apply this approach to Mars, Earth, and Venus, demonstrating the information contained in the layer radiative properties and their derivatives, as well as how the LiFE approach can be used to determine the thermal structure of radiative and radiative-convective equilibrium states in one-dimensional atmospheric models.

Verification and Validation of a Navy ESPC Hindcast with Loosely Coupled Data Assimilation

NASA Astrophysics Data System (ADS)

Metzger, E. J.; Barton, N. P.; Smedstad, O. M.; Ruston, B. C.; Wallcraft, A. J.; Whitcomb, T. R.; Ridout, J. A.; Franklin, D. S.; Zamudio, L.; Posey, P. G.; Reynolds, C. A.; Phelps, M.

2016-12-01

The US Navy is developing an Earth System Prediction Capability (ESPC) to provide global environmental information to meet Navy and Department of Defense (DoD) operations and planning needs from the upper atmosphere to under the sea. It will be a fully coupled global atmosphere/ocean/ice/wave/land prediction system providing daily deterministic forecasts out to 16 days at high horizontal and vertical resolution, and daily probabilistic forecasts out to 45 days at lower resolution. The system will run at the Navy DoD Supercomputing Resource Center with an initial operational capability scheduled for the end of FY18 and the final operational capability scheduled for FY22. The individual model and data assimilation components include: atmosphere - NAVy Global Environmental Model (NAVGEM) and Naval Research Laboratory (NRL) Atmospheric Variational Data Assimilation System - Accelerated Representer (NAVDAS-AR); ocean - HYbrid Coordinate Ocean Model (HYCOM) and Navy Coupled Ocean Data Assimilation (NCODA); ice - Community Ice CodE (CICE) and NCODA; WAVEWATCH III™ and NCODA; and land - NAVGEM Land Surface Model (LSM). Currently, NAVGEM/HYCOM/CICE are three-way coupled and each model component is cycling with its respective assimilation scheme. The assimilation systems do not communicate with each other, but future plans call for these to be coupled as well. NAVGEM runs with a 6-hour update cycle while HYCOM/CICE run with a 24-hour update cycle. The T359L50 NAVGEM/0.08° HYCOM/0.08° CICE system has been integrated in hindcast mode and verification/validation metrics have been computed against unassimilated observations and against stand-alone versions of NAVGEM and HYCOM/CICE. This presentation will focus on typical operational diagnostics for atmosphere, ocean, and ice analyses including 500 hPa atmospheric height anomalies, low-level winds, temperature/salinity ocean depth profiles, ocean acoustical proxies, sea ice edge, and sea ice drift. Overall, the global coupled ESPC system is performing with comparable skill to the stand-alone systems at the nowcast time.

Determination of equivalent sound speed profiles for ray tracing in near-ground sound propagation.

PubMed

Prospathopoulos, John M; Voutsinas, Spyros G

2007-09-01

The determination of appropriate sound speed profiles in the modeling of near-ground propagation using a ray tracing method is investigated using a ray tracing model which is capable of performing axisymmetric calculations of the sound field around an isolated source. Eigenrays are traced using an iterative procedure which integrates the trajectory equations for each ray launched from the source at a specific direction. The calculation of sound energy losses is made by introducing appropriate coefficients to the equations representing the effect of ground and atmospheric absorption and the interaction with the atmospheric turbulence. The model is validated against analytical and numerical predictions of other methodologies for simple cases, as well as against measurements for nonrefractive atmospheric environments. A systematic investigation for near-ground propagation in downward and upward refractive atmosphere is made using experimental data. Guidelines for the suitable simulation of the wind velocity profile are derived by correlating predictions with measurements.

The annual pressure cycle on Mars: Results from the LMD Martian atmospheric general circulation model

NASA Technical Reports Server (NTRS)

Hourdin, Frederic; Forget, Francois; Talagrand, O.

1993-01-01

We have been developing a General Circulation Model (GCM) of the martian atmosphere since 1989. The model has been described rather extensively elsewhere and only the main characteristics are given here. The dynamical part of the model, adapted from the LMD terrestrial climate model, is based on a finite-difference formulation of the classical 'primitive equations of meteorology.' The radiative transfer code includes absorption and emission by CO2 (carefully validated by comparison to line-by-line calculations) and dust in the thermal range and absorption and scattering by dust in the visible range. Other physical parameterizations are included: modeling of vertical turbulent mixing, dry convective adjustment (in order to prevent vertical unstable temperature profiles), and a multilayer model of the thermal conduction in the soil. Finally, the condensation-sublimation of CO2 is introduced through specification of a pressure-dependent condensation temperature. The atmospheric and surface temperatures are prevented from falling below this critical temperature by condensation and direct precipitation onto the surface of atmospheric CO2. The only prespecified spatial fields are the surface thermal inertia, albedo, and topography.

MODTRAN Radiance Modeling of Multi-Angle Worldview-2 Imagery

DTIC Science & Technology

2013-09-01

this thesis, multi-angle CHRIS data has been used to validate canopy BRDF models generated using PROSPECT and SAILH radiative transfer models (D’Urso...67 1. MODTRAN Modeling using BRDF Algorithms .............................67 2. MODTRAN Modeling of Hyperspectral Data...associated with BRDF , and (2) develop software- 2 based atmospheric models , using parameters similar to those found in the imagery, for comparison to

Capturing atmospheric effects on 3D millimeter wave radar propagation patterns

NASA Astrophysics Data System (ADS)

Cook, Richard D.; Fiorino, Steven T.; Keefer, Kevin J.; Stringer, Jeremy

2016-05-01

Traditional radar propagation modeling is done using a path transmittance with little to no input for weather and atmospheric conditions. As radar advances into the millimeter wave (MMW) regime, atmospheric effects such as attenuation and refraction become more pronounced than at traditional radar wavelengths. The DoD High Energy Laser Joint Technology Offices High Energy Laser End-to-End Operational Simulation (HELEEOS) in combination with the Laser Environmental Effects Definition and Reference (LEEDR) code have shown great promise simulating atmospheric effects on laser propagation. Indeed, the LEEDR radiative transfer code has been validated in the UV through RF. Our research attempts to apply these models to characterize the far field radar pattern in three dimensions as a signal propagates from an antenna towards a point in space. Furthermore, we do so using realistic three dimensional atmospheric profiles. The results from these simulations are compared to those from traditional radar propagation software packages. In summary, a fast running method has been investigated which can be incorporated into computational models to enhance understanding and prediction of MMW propagation through various atmospheric and weather conditions.

Estimated congener specific gas-phase atmospheric behavior and fractionation of perfluoroalkyl compounds: rates of reaction with atmospheric oxidants, air-water partitioning, and wet/dry deposition lifetimes.

PubMed

Rayne, Sierra; Forest, Kaya; Friesen, Ken J

2009-08-01

A quantitative structure-activity model has been validated for estimating congener specific gas-phase hydroxyl radical reaction rates for perfluoroalkyl sulfonic acids (PFSAs), carboxylic acids (PFCAs), aldehydes (PFAls) and dihydrates, fluorotelomer olefins (FTOls), alcohols (FTOHs), aldehydes (FTAls), and acids (FTAcs), and sulfonamides (SAs), sulfonamidoethanols (SEs), and sulfonamido carboxylic acids (SAAs), and their alkylated derivatives based on calculated semi-empirical PM6 method ionization potentials. Corresponding gas-phase reaction rates with nitrate radicals and ozone have also been estimated using the computationally derived ionization potentials. Henry's law constants for these classes of perfluorinated compounds also appear to be reasonably approximated by the SPARC software program, thereby allowing estimation of wet and dry atmospheric deposition rates. Both congener specific gas-phase atmospheric and air-water interface fractionation of these compounds is expected, complicating current source apportionment perspectives and necessitating integration of such differential partitioning influences into future multimedia models. The findings will allow development and refinement of more accurate and detailed local through global scale atmospheric models for the atmospheric fate of perfluoroalkyl compounds.

Comments on “A Unified Representation of Deep Moist Convection in Numerical Modeling of the Atmosphere. Part I”

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Guang; Fan, Jiwen; Xu, Kuan-Man

2015-06-01

Arakawa and Wu (2013, hereafter referred to as AW13) recently developed a formal approach to a unified parameterization of atmospheric convection for high-resolution numerical models. The work is based on ideas formulated by Arakawa et al. (2011). It lays the foundation for a new parameterization pathway in the era of high-resolution numerical modeling of the atmosphere. The key parameter in this approach is convective cloud fraction. In conventional parameterization, it is assumed that <<1. This assumption is no longer valid when horizontal resolution of numerical models approaches a few to a few tens kilometers, since in such situations convective cloudmore » fraction can be comparable to unity. Therefore, they argue that the conventional approach to parameterizing convective transport must include a factor 1 - in order to unify the parameterization for the full range of model resolutions so that it is scale-aware and valid for large convective cloud fractions. While AW13’s approach provides important guidance for future convective parameterization development, in this note we intend to show that the conventional approach already has this scale awareness factor 1 - built in, although not recognized for the last forty years. Therefore, it should work well even in situations of large convective cloud fractions in high-resolution numerical models.« less

High Vertically Resolved Atmospheric State Revealed with IASI Single FOV Retrievals under All-weather Conditions

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schluessel, L. Peter; Strow, Larrybee; Mango, Stephen A.

2008-01-01

The Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite was launched on October 19, 2006. The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25 cm(exp -1) and a spectral coverage from 645 to 2760 cm(exp -1). Ultra-spectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed - Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated to benefit future NPOESS operation.

Validation of the Fully-Coupled Air-Sea-Wave COAMPS System

NASA Astrophysics Data System (ADS)

Smith, T.; Campbell, T. J.; Chen, S.; Gabersek, S.; Tsu, J.; Allard, R. A.

2017-12-01

A fully-coupled, air-sea-wave numerical model, COAMPS®, has been developed by the Naval Research Laboratory to further enhance understanding of oceanic, atmospheric, and wave interactions. The fully-coupled air-sea-wave system consists of an atmospheric component with full physics parameterizations, an ocean model, NCOM (Navy Coastal Ocean Model), and two wave components, SWAN (Simulating Waves Nearshore) and WaveWatch III. Air-sea interactions between the atmosphere and ocean components are accomplished through bulk flux formulations of wind stress and sensible and latent heat fluxes. Wave interactions with the ocean include the Stokes' drift, surface radiation stresses, and enhancement of the bottom drag coefficient in shallow water due to the wave orbital velocities at the bottom. In addition, NCOM surface currents are provided to SWAN and WaveWatch III to simulate wave-current interaction. The fully-coupled COAMPS system was executed for several regions at both regional and coastal scales for the entire year of 2015, including the U.S. East Coast, Western Pacific, and Hawaii. Validation of COAMPS® includes observational data comparisons and evaluating operational performance on the High Performance Computing (HPC) system for each of these regions.

Global horizontal irradiance clear sky models : implementation and analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stein, Joshua S.; Hansen, Clifford W.; Reno, Matthew J.

2012-03-01

Clear sky models estimate the terrestrial solar radiation under a cloudless sky as a function of the solar elevation angle, site altitude, aerosol concentration, water vapor, and various atmospheric conditions. This report provides an overview of a number of global horizontal irradiance (GHI) clear sky models from very simple to complex. Validation of clear-sky models requires comparison of model results to measured irradiance during clear-sky periods. To facilitate validation, we present a new algorithm for automatically identifying clear-sky periods in a time series of GHI measurements. We evaluate the performance of selected clear-sky models using measured data from 30 differentmore » sites, totaling about 300 site-years of data. We analyze the variation of these errors across time and location. In terms of error averaged over all locations and times, we found that complex models that correctly account for all the atmospheric parameters are slightly more accurate than other models, but, primarily at low elevations, comparable accuracy can be obtained from some simpler models. However, simpler models often exhibit errors that vary with time of day and season, whereas the errors for complex models vary less over time.« less

The zonally averaged transport characteristics of the atmosphere as determined by a general circulation model

NASA Technical Reports Server (NTRS)

Plumb, R. A.

1985-01-01

Two dimensional modeling has become an established technique for the simulation of the global structure of trace constituents. Such models are simpler to formulate and cheaper to operate than three dimensional general circulation models, while avoiding some of the gross simplifications of one dimensional models. Nevertheless, the parameterization of eddy fluxes required in a 2-D model is not a trivial problem. This fact has apparently led some to interpret the shortcomings of existing 2-D models as indicating that the parameterization procedure is wrong in principle. There are grounds to believe that these shortcomings result primarily from incorrect implementations of the predictions of eddy transport theory and that a properly based parameterization may provide a good basis for atmospheric modeling. The existence of these GCM-derived coefficients affords an unprecedented opportunity to test the validity of the flux-gradient parameterization. To this end, a zonally averaged (2-D) model was developed, using these coefficients in the transport parameterization. Results from this model for a number of contrived tracer experiments were compared with the parent GCM. The generally good agreement substantially validates the flus-gradient parameterization, and thus the basic principle of 2-D modeling.

Is the ;Earth-ionosphere capacitor; a valid component in the atmospheric global electric circuit?

NASA Astrophysics Data System (ADS)

Haldoupis, Christos; Rycroft, Michael; Williams, Earle; Price, Colin

2017-11-01

This paper examines whether the Earth-ionosphere capacitor (EIC) model is correct, by comparing observed atmospheric electrical properties with those expected for a spherical capacitor, as defined in electrostatics. The comparisons suggest that the EIC concept cannot be reconciled with, and hence cannot account for, the observations, particularly the rapid reduction of the atmospheric electric field with height that is measured. This means that the spherical EIC concept is incorrect by being too simplistic; it is thus misleading. The reason for this flawed concept is simple: the model disregards the non-uniform conductivity of the atmosphere which requires the presence of a net positive charge in the lower atmosphere that equals in magnitude the Earth's negative charge. This positive charge shields the action of the Earth's negative charge from polarizing the ionosphere positively. Thus, the lower D region ionosphere remains electrically neutral, which makes the EIC concept inappropriate.

Nontidal Loading Applied in VLBI Geodetic Analysis

NASA Astrophysics Data System (ADS)

MacMillan, D. S.

2015-12-01

We investigate the application of nontidal atmosphere pressure, hydrology, and ocean loading series in the analysis of VLBI data. The annual amplitude of VLBI scale variation is reduced to less than 0.1 ppb, a result of the annual components of the vertical loading series. VLBI site vertical scatter and baseline length scatter is reduced when these loading models are applied. We operate nontidal loading services for hydrology loading (GLDAS model), atmospheric pressure loading (NCEP), and nontidal ocean loading (JPL ECCO model). As an alternative validation, we compare these loading series with corresponding series generated by other analysis centers.

Forest Canopy Heights in Amazon River Basin Forests as Estimated with the Geoscience Laser Altimeter System (GLAS)

Treesearch

E. H. Helmer; M. A. Lefsky

2006-01-01

Land-use change, mainly forest burning, harvest, or clearing for agriculture, may compose 15 to 40 percent of annual human-caused emissions of carbon (C) to the atmosphere. Spatially extensive data on forest C pools can validate and parameterize atmospheric and ecosystem models of those fluxes and quantify fluxes from forest change. Excellent evidence exists that light...

Evaluating Land-Atmosphere Interactions with the North American Soil Moisture Database

NASA Astrophysics Data System (ADS)

Giles, S. M.; Quiring, S. M.; Ford, T.; Chavez, N.; Galvan, J.

2015-12-01

The North American Soil Moisture Database (NASMD) is a high-quality observational soil moisture database that was developed to study land-atmosphere interactions. It includes over 1,800 monitoring stations the United States, Canada and Mexico. Soil moisture data are collected from multiple sources, quality controlled and integrated into an online database (soilmoisture.tamu.edu). The period of record varies substantially and only a few of these stations have an observation record extending back into the 1990s. Daily soil moisture observations have been quality controlled using the North American Soil Moisture Database QAQC algorithm. The database is designed to facilitate observationally-driven investigations of land-atmosphere interactions, validation of the accuracy of soil moisture simulations in global land surface models, satellite calibration/validation for SMOS and SMAP, and an improved understanding of how soil moisture influences climate on seasonal to interannual timescales. This paper provides some examples of how the NASMD has been utilized to enhance understanding of land-atmosphere interactions in the U.S. Great Plains.

How to Model Super-Soft X-ray Sources?

NASA Astrophysics Data System (ADS)

Rauch, Thomas

2012-07-01

During outbursts, the surface temperatures of white dwarfs in cataclysmic variables exceed by far half a million Kelvin. In this phase, they may become the brightest super-soft sources (SSS) in the sky. Time-series of high-resolution, high S/N X-ray spectra taken during rise, maximum, and decline of their X-ray luminosity provide insights into the processes following such outbursts as well as in the surface composition of the white dwarf. Their analysis requires adequate NLTE model atmospheres. The Tuebingen Non-LTE Model-Atmosphere Package (TMAP) is a powerful tool for their calculation. We present the application of TMAP models to SSS spectra and discuss their validity.

Ocean-Atmosphere Coupled Model Simulations of Precipitation in the Central Andes

NASA Technical Reports Server (NTRS)

Nicholls, Stephen D.; Mohr, Karen I.

2015-01-01

The meridional extent and complex orography of the South American continent contributes to a wide diversity of climate regimes ranging from hyper-arid deserts to tropical rainforests to sub-polar highland regions. In addition, South American meteorology and climate are also made further complicated by ENSO, a powerful coupled ocean-atmosphere phenomenon. Modelling studies in this region have typically resorted to either atmospheric mesoscale or atmosphere-ocean coupled global climate models. The latter offers full physics and high spatial resolution, but it is computationally inefficient typically lack an interactive ocean, whereas the former offers high computational efficiency and ocean-atmosphere coupling, but it lacks adequate spatial and temporal resolution to adequate resolve the complex orography and explicitly simulate precipitation. Explicit simulation of precipitation is vital in the Central Andes where rainfall rates are light (0.5-5 mm hr-1), there is strong seasonality, and most precipitation is associated with weak mesoscale-organized convection. Recent increases in both computational power and model development have led to the advent of coupled ocean-atmosphere mesoscale models for both weather and climate study applications. These modelling systems, while computationally expensive, include two-way ocean-atmosphere coupling, high resolution, and explicit simulation of precipitation. In this study, we use the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST), a fully-coupled mesoscale atmosphere-ocean modeling system. Previous work has shown COAWST to reasonably simulate the entire 2003-2004 wet season (Dec-Feb) as validated against both satellite and model analysis data when ECMWF interim analysis data were used for boundary conditions on a 27-9-km grid configuration (Outer grid extent: 60.4S to 17.7N and 118.6W to 17.4W).

Soil Moisture Memory in Climate Models

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Suarez, Max J.; Zukor, Dorothy J. (Technical Monitor)

2000-01-01

Water balance considerations at the soil surface lead to an equation that relates the autocorrelation of soil moisture in climate models to (1) seasonality in the statistics of the atmospheric forcing, (2) the variation of evaporation with soil moisture, (3) the variation of runoff with soil moisture, and (4) persistence in the atmospheric forcing, as perhaps induced by land atmosphere feedback. Geographical variations in the relative strengths of these factors, which can be established through analysis of model diagnostics and which can be validated to a certain extent against observations, lead to geographical variations in simulated soil moisture memory and thus, in effect, to geographical variations in seasonal precipitation predictability associated with soil moisture. The use of the equation to characterize controls on soil moisture memory is demonstrated with data from the modeling system of the NASA Seasonal-to-Interannual Prediction Project.

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

NASA Astrophysics Data System (ADS)

Way, M. J.; Aleinov, I.; Amundsen, David S.; Chandler, M. A.; Clune, T. L.; Del Genio, A. D.; Fujii, Y.; Kelley, M.; Kiang, N. Y.; Sohl, L.; Tsigaridis, K.

2017-07-01

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth’s, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn’s moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

NASA Technical Reports Server (NTRS)

Way, M. J.; Aleinov, I.; Amundsen, David S.; Chandler, M. A.; Clune, T. L.; Del Genio, A.; Fujii, Y.; Kelley, M.; Kiang, N. Y.; Sohl, L.;

Laboratory evidence for a key intermediate in the Venus atmosphere: Peroxychloroformyl radical

PubMed Central

Pernice, Holger; Garcia, Placido; Willner, Helge; Francisco, Joseph S.; Mills, Franklin P.; Allen, Mark; Yung, Yuk L.

2004-01-01

For two decades, the peroxychloroformyl radical, ClC(O)OO, has played a central role in models of the chemical stability of the Venus atmosphere. No confirmation, however, has been possible in the absence of laboratory measurements for ClC(O)OO. We report the isolation of ClC(O)OO in a cryogenic matrix and its infrared and ultraviolet spectral signatures. These experiments show that ClC(O)OO is thermally and photolytically stable in the Venus atmosphere. These experimental discoveries validate the existence of ClC(O)OO, confirm several longstanding model assumptions, and provide a basis for the astronomical search for this important radical species. PMID:15375212

Laboratory Evidence for a Key Intermediate in the Venus Atmosphere: Peroxychloroformyl Radical

NASA Technical Reports Server (NTRS)

Pernice, Holger; Garcia, Placido; Willner, Helge; Francisco, Joseph S.; Mills, Franklin P.; Allen, Mark; Yung, Yuk L.

2004-01-01

For two decades, the peroxychloroformyl radical, ClC(O)OO, has played a central role in models of the chemical stability of the Venus atmosphere. No confirmation, however, has been possible in the absence of laboratory measurements for ClC(O)OO. We report the isolation of ClC(O)OO in a cryogenic matrix and its infrared and ultraviolet spectral signatures. These experiments show that ClC(O)OO is thermally and photolytically stable in the Venus atmosphere. These experimental discoveries validate the existence of ClC(O)OO, confirm several longstanding model assumptions, and provide a basis for the astronomical search for this important radical species.

Improved Products for Assimilation and Model Validation from the Atmospheric Infrared Sounder (AIRS) on Aqua

NASA Technical Reports Server (NTRS)

Pagano, Thomas S.

2008-01-01

The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. AIRS acquires hyperspectral infrared radiances in the 3.7-15.4 micrometer spectral region with spectral resolution of better than 1200. Key channels from the AIRS Level 1B calibrated radiance product are currently assimilated into operational weather forecasts at NCEP and other international agencies. Additional Level 2 products for assimilation include the AIRS cloud cleared radiances and the geophysical retrieved temperature and water vapor profiles. The AIRS products are also used to validate climate model vertical and horizontal biases and transport of water vapor and key trace gases including Carbon Dioxide and Ozone. The wide variety of products available from the AIRS make it well suited to study processes affecting the interaction of these products.

Diagnosing land management and climate change impacts on snowmelt in semi-arid agricultural cold regions with an improved snowmelt model

NASA Astrophysics Data System (ADS)

Harder, P.; Pomeroy, J. W.; Helgason, W.

2017-12-01

Spring snowmelt is the most important hydrological event in semi-arid agricultural cold regions, recharging soil moisture and generating the majority of annual runoff. Adoption of no-till agricultural practices means vast areas of the Canadian Prairies, and other analogous regions, are characterized by standing crop stubble. The emergence of stubble during snowmelt will have important implications for the snowpack energy balance. In addition, spatiotemporally dynamic snowcover heterogeneity leads to enhancement of turbulent flux contributions to melt by advection of energy from warm moist bare ground to snow. Stubble emergence and advection are generally unaccounted for in snow models. To address these challenges a stubble-snow-atmosphere surface energy balance model is developed that relates stubble parameters to the snow surface energy balance. Existing fractal understandings of snowcover geometry are applied to a conceptualized boundary layer integration model to estimate a sensible and latent heat advection efficiency. The small-scale nature of stubble-snow-atmosphere interactions makes direct validation of the energy balance terms challenging. However, the energy balance estimates are assessed by comparing to measured snow and stubble surface temperatures, snow surface incoming shortwave radiation and areal average turbulent fluxes. Advection estimates are validated from a two-dimensional air temperature, water vapor and windspeed profiles. Snowcover geometry relationships are validated/updated with unmanned air vehicle observations. Observations for model assessment occurred in 2015 and 2016 on wheat and canola stubble fields in north-central Saskatchewan, Canada. The model is not calibrated to melt rates, yet compares well with available observations, providing confidence in the model structure and parameterization. Sensitivity analysis using the model revealed compensatory relationships in energy balance terms resulting in limited reduction of energy available for snowmelt as stubble height increases. The proposed model is used to diagnose the influence of stubble management and climate change on melt processes to reveal the potential implications on runoff generation, infiltration and land-atmosphere interactions.

Mars Entry Atmospheric Data System Modelling and Algorithm Development

NASA Technical Reports Server (NTRS)

Karlgaard, Christopher D.; Beck, Roger E.; OKeefe, Stephen A.; Siemers, Paul; White, Brady; Engelund, Walter C.; Munk, Michelle M.

2009-01-01

The Mars Entry Atmospheric Data System (MEADS) is being developed as part of the Mars Science Laboratory (MSL), Entry, Descent, and Landing Instrumentation (MEDLI) project. The MEADS project involves installing an array of seven pressure transducers linked to ports on the MSL forebody to record the surface pressure distribution during atmospheric entry. These measured surface pressures are used to generate estimates of atmospheric quantities based on modeled surface pressure distributions. In particular, the quantities to be estimated from the MEADS pressure measurements include the total pressure, dynamic pressure, Mach number, angle of attack, and angle of sideslip. Secondary objectives are to estimate atmospheric winds by coupling the pressure measurements with the on-board Inertial Measurement Unit (IMU) data. This paper provides details of the algorithm development, MEADS system performance based on calibration, and uncertainty analysis for the aerodynamic and atmospheric quantities of interest. The work presented here is part of the MEDLI performance pre-flight validation and will culminate with processing flight data after Mars entry in 2012.

Synergies Between Grace and Regional Atmospheric Modeling Efforts

NASA Astrophysics Data System (ADS)

Kusche, J.; Springer, A.; Ohlwein, C.; Hartung, K.; Longuevergne, L.; Kollet, S. J.; Keune, J.; Dobslaw, H.; Forootan, E.; Eicker, A.

2014-12-01

In the meteorological community, efforts converge towards implementation of high-resolution (< 12km) data-assimilating regional climate modelling/monitoring systems based on numerical weather prediction (NWP) cores. This is driven by requirements of improving process understanding, better representation of land surface interactions, atmospheric convection, orographic effects, and better forecasting on shorter timescales. This is relevant for the GRACE community since (1) these models may provide improved atmospheric mass separation / de-aliasing and smaller topography-induced errors, compared to global (ECMWF-Op, ERA-Interim) data, (2) they inherit high temporal resolution from NWP models, (3) parallel efforts towards improving the land surface component and coupling groundwater models; this may provide realistic hydrological mass estimates with sub-diurnal resolution, (4) parallel efforts towards re-analyses, with the aim of providing consistent time series. (5) On the other hand, GRACE can help validating models and aids in the identification of processes needing improvement. A coupled atmosphere - land surface - groundwater modelling system is currently being implemented for the European CORDEX region at 12.5 km resolution, based on the TerrSysMP platform (COSMO-EU NWP, CLM land surface and ParFlow groundwater models). We report results from Springer et al. (J. Hydromet., accept.) on validating the water cycle in COSMO-EU using GRACE and precipitation, evapotranspiration and runoff data; confirming that the model does favorably at representing observations. We show that after GRACE-derived bias correction, basin-average hydrological conditions prior to 2002 can be reconstructed better than before. Next, comparing GRACE with CLM forced by EURO-CORDEX simulations allows identifying processes needing improvement in the model. Finally, we compare COSMO-EU atmospheric pressure, a proxy for mass corrections in satellite gravimetry, with ERA-Interim over Europe at timescales shorter/longer than 1 month, and spatial scales below/above ERA resolution. We find differences between regional and global model more pronounced at high frequencies, with magnitude at sub-grid scale and larger scale corresponding to 1-3 hPa (1-3 cm EWH); relevant for the assessment of post-GRACE concepts.

Estimations of natural variability between satellite measurements of trace species concentrations

NASA Astrophysics Data System (ADS)

Sheese, P.; Walker, K. A.; Boone, C. D.; Degenstein, D. A.; Kolonjari, F.; Plummer, D. A.; von Clarmann, T.

2017-12-01

In order to validate satellite measurements of atmospheric states, it is necessary to understand the range of random and systematic errors inherent in the measurements. On occasions where the measurements do not agree within those errors, a common "go-to" explanation is that the unexplained difference can be chalked up to "natural variability". However, the expected natural variability is often left ambiguous and rarely quantified. This study will look to quantify the expected natural variability of both O3 and NO2 between two satellite instruments: ACE-FTS (Atmospheric Chemistry Experiment - Fourier Transform Spectrometer) and OSIRIS (Optical Spectrograph and Infrared Imaging System). By sampling the CMAM30 (30-year specified dynamics simulation of the Canadian Middle Atmosphere Model) climate chemistry model throughout the upper troposphere and stratosphere at times and geolocations of coincident ACE-FTS and OSIRIS measurements at varying coincidence criteria, height-dependent expected values of O3 and NO2 variability will be estimated and reported on. The results could also be used to better optimize the coincidence criteria used in satellite measurement validation studies.

Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide

NASA Astrophysics Data System (ADS)

Frankenberg, Christian; Kulawik, Susan S.; Wofsy, Steven C.; Chevallier, Frédéric; Daube, Bruce; Kort, Eric A.; O'Dell, Christopher; Olsen, Edward T.; Osterman, Gregory

2016-06-01

In recent years, space-borne observations of atmospheric carbon dioxide (CO2) have been increasingly used in global carbon-cycle studies. In order to obtain added value from space-borne measurements, they have to suffice stringent accuracy and precision requirements, with the latter being less crucial as it can be reduced by just enhanced sample size. Validation of CO2 column-averaged dry air mole fractions (XCO2) heavily relies on measurements of the Total Carbon Column Observing Network (TCCON). Owing to the sparseness of the network and the requirements imposed on space-based measurements, independent additional validation is highly valuable. Here, we use observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) flights from 01/2009 through 09/2011 to validate CO2 measurements from satellites (Greenhouse Gases Observing Satellite - GOSAT, Thermal Emission Sounder - TES, Atmospheric Infrared Sounder - AIRS) and atmospheric inversion models (CarbonTracker CT2013B, Monitoring Atmospheric Composition and Climate (MACC) v13r1). We find that the atmospheric models capture the XCO2 variability observed in HIPPO flights very well, with correlation coefficients (r2) of 0.93 and 0.95 for CT2013B and MACC, respectively. Some larger discrepancies can be observed in profile comparisons at higher latitudes, in particular at 300 hPa during the peaks of either carbon uptake or release. These deviations can be up to 4 ppm and hint at misrepresentation of vertical transport. Comparisons with the GOSAT satellite are of comparable quality, with an r2 of 0.85, a mean bias μ of -0.06 ppm, and a standard deviation σ of 0.45 ppm. TES exhibits an r2 of 0.75, μ of 0.34 ppm, and σ of 1.13 ppm. For AIRS, we find an r2 of 0.37, μ of 1.11 ppm, and σ of 1.46 ppm, with latitude-dependent biases. For these comparisons at least 6, 20, and 50 atmospheric soundings have been averaged for GOSAT, TES, and AIRS, respectively. Overall, we find that GOSAT soundings over the remote Pacific Ocean mostly meet the stringent accuracy requirements of about 0.5 ppm for space-based CO2 observations.

The ice-core record - Climate sensitivity and future greenhouse warming

NASA Technical Reports Server (NTRS)

Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

1990-01-01

The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

Submillimeter atmospheric FTS at the geographic South Pole

NASA Astrophysics Data System (ADS)

Chamberlin, Richard A.; Martin, Robert N.; Martin, Christopher L.; Stark, Antony A.

2003-02-01

A submillimeter Fourier Transform Spectrometer of the Martin-Puplett type was constructed and deployed to the geographical South Pole in 2001. The instrument operates from about 300 GHz to almost 2 THz and was used over winter to acquire atmospheric spectra with resolution as fine as 250 MHz. The main motivation for constructing and deploying this FTS was for astronomical site testing, but the obtained spectra can have important secondary uses in atmospheric science and transmission model validation. Some preliminary, low spectral resolution site testing results are presented here.

Do state-of-the-art CMIP5 ESMs accurately represent observed vegetation-rainfall feedbacks? Focus on the Sahel

NASA Astrophysics Data System (ADS)

Notaro, M.; Wang, F.; Yu, Y.; Mao, J.; Shi, X.; Wei, Y.

2017-12-01

The semi-arid Sahel ecoregion is an established hotspot of land-atmosphere coupling. Ocean-land-atmosphere interactions received considerable attention by modeling studies in response to the devastating 1970s-90s Sahel drought, which models suggest was driven by sea-surface temperature (SST) anomalies and amplified by local vegetation-atmosphere feedbacks. Vegetation affects the atmosphere through biophysical feedbacks by altering the albedo, roughness, and transpiration and thereby modifying exchanges of energy, momentum, and moisture with the atmosphere. The current understanding of these potentially competing processes is primarily based on modeling studies, with biophysical feedbacks serving as a key uncertainty source in regional climate change projections among Earth System Models (ESMs). In order to reduce this uncertainty, it is critical to rigorously evaluate the representation of vegetation feedbacks in ESMs against an observational benchmark in order to diagnose systematic biases and their sources. However, it is challenging to successfully isolate vegetation's feedbacks on the atmosphere, since the atmospheric control on vegetation growth dominates the atmospheric feedback response to vegetation anomalies and the atmosphere is simultaneously influenced by oceanic and terrestrial anomalies. In response to this challenge, a model-validated multivariate statistical method, Stepwise Generalized Equilibrium Feedback Assessment (SGEFA), is developed, which extracts the forcing of a slowly-evolving environmental variable [e.g. SST or leaf area index (LAI)] on the rapidly-evolving atmosphere. By applying SGEFA to observational and remotely-sensed data, an observational benchmark is established for Sahel vegetation feedbacks. In this work, the simulated responses in key atmospheric variables, including evapotranspiration, albedo, wind speed, vertical motion, temperature, stability, and rainfall, to Sahel LAI anomalies are statistically assessed in Coupled Model Intercomparison Project Phase 5 (CMIP5) ESMs through SGEFA. The dominant mechanism, such as albedo feedback, moisture recycling, or momentum feedback, in each ESM is evaluated against the observed benchmark. SGEFA facilitates a systematic assessment of model biases in land-atmosphere interactions.

Global Validation of MODIS Atmospheric Profile-Derived Near-Surface Air Temperature and Dew Point Estimates

NASA Astrophysics Data System (ADS)

Famiglietti, C.; Fisher, J.; Halverson, G. H.

2017-12-01

This study validates a method of remote sensing near-surface meteorology that vertically interpolates MODIS atmospheric profiles to surface pressure level. The extraction of air temperature and dew point observations at a two-meter reference height from 2001 to 2014 yields global moderate- to fine-resolution near-surface temperature distributions that are compared to geographically and temporally corresponding measurements from 114 ground meteorological stations distributed worldwide. This analysis is the first robust, large-scale validation of the MODIS-derived near-surface air temperature and dew point estimates, both of which serve as key inputs in models of energy, water, and carbon exchange between the land surface and the atmosphere. Results show strong linear correlations between remotely sensed and in-situ near-surface air temperature measurements (R2 = 0.89), as well as between dew point observations (R2 = 0.77). Performance is relatively uniform across climate zones. The extension of mean climate-wise percent errors to the entire remote sensing dataset allows for the determination of MODIS air temperature and dew point uncertainties on a global scale.

A model for calculating the vertical distribution of the atmospheric electric potential in the exchange layer in a maritime clean atmosphere

NASA Astrophysics Data System (ADS)

Kulkarni, M. N.; Kamra, A. K.

2012-11-01

A theoretical model is developed for calculating the vertical distribution of atmospheric electric potential in exchange layer of maritime clean atmosphere. The transport of space charge in electrode layer acts as a convective generator in this model and plays a major role in determining potential distribution in vertical. Eddy diffusion is the main mechanism responsible for the distribution of space charge in vertical. Our results show that potential at a particular level increases with increase in the strength of eddy diffusion under similar conditions. A method is suggested to estimate columnar resistance, the ionospheric potential and the vertical atmospheric electric potential distribution in exchange layer from measurements of total air-earth current density and surface electric field made over oceans. The results are validated and found to be in very good agreement with the previous aircraft measurements. Different parameters involved in the proposed methodology can be determined either theoretically, as in the present work, or experimentally using the near surface atmospheric electrical measurements or using some other surface-based measurement technique such as LIDAR. A graphical relationship between the atmospheric eddy diffusion coefficient and height of exchange layer obtained from atmospheric electrical approach, is reported.

Design and Performance of the Sorbent-Based Atmosphere Revitalization System for Orion

NASA Technical Reports Server (NTRS)

Ritter, James A.; Reynolds, Steven P.; Ebner, Armin D.; Knox, James C.; LeVan, M. Douglas

2007-01-01

Validation and simulations of a real-time dynamic cabin model were conducted on the sorbent-based atmosphere revitalization system for Orion. The dynamic cabin model, which updates the concentration of H2O and CO2 every second during the simulation, was able to predict the steady state model values for H2O and CO2 for long periods of steady metabolic production for a 4-person crew. It also showed similar trends for the exercise periods, where there were quick changes in production rates. Once validated, the cabin model was used to determine the effects of feed flow rate, cabin volume and column volume. A higher feed flow rate reduced the cabin concentrations only slightly over the base case, a larger cabin volume was able to reduce the cabin concentrations even further, and the lower column volume led to much higher cabin concentrations. Finally, the cabin model was used to determine the effect of the amount of silica gel in the column. As the amount increased, the cabin concentration of H2O decreased, but the cabin concentration of CO2 increased.

Constraining terrestrial ecosystem CO2 fluxes by integrating models of biogeochemistry and atmospheric transport and data of surface carbon fluxes and atmospheric CO2 concentrations

NASA Astrophysics Data System (ADS)

Zhu, Q.; Zhuang, Q.; Henze, D.; Bowman, K.; Chen, M.; Liu, Y.; He, Y.; Matsueda, H.; Machida, T.; Sawa, Y.; Oechel, W.

2014-09-01

Regional net carbon fluxes of terrestrial ecosystems could be estimated with either biogeochemistry models by assimilating surface carbon flux measurements or atmospheric CO2 inversions by assimilating observations of atmospheric CO2 concentrations. Here we combine the ecosystem biogeochemistry modeling and atmospheric CO2 inverse modeling to investigate the magnitude and spatial distribution of the terrestrial ecosystem CO2 sources and sinks. First, we constrain a terrestrial ecosystem model (TEM) at site level by assimilating the observed net ecosystem production (NEP) for various plant functional types. We find that the uncertainties of model parameters are reduced up to 90% and model predictability is greatly improved for all the plant functional types (coefficients of determination are enhanced up to 0.73). We then extrapolate the model to a global scale at a 0.5° × 0.5° resolution to estimate the large-scale terrestrial ecosystem CO2 fluxes, which serve as prior for atmospheric CO2 inversion. Second, we constrain the large-scale terrestrial CO2 fluxes by assimilating the GLOBALVIEW-CO2 and mid-tropospheric CO2 retrievals from the Atmospheric Infrared Sounder (AIRS) into an atmospheric transport model (GEOS-Chem). The transport inversion estimates that: (1) the annual terrestrial ecosystem carbon sink in 2003 is -2.47 Pg C yr-1, which agrees reasonably well with the most recent inter-comparison studies of CO2 inversions (-2.82 Pg C yr-1); (2) North America temperate, Europe and Eurasia temperate regions act as major terrestrial carbon sinks; and (3) The posterior transport model is able to reasonably reproduce the atmospheric CO2 concentrations, which are validated against Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) CO2 concentration data. This study indicates that biogeochemistry modeling or atmospheric transport and inverse modeling alone might not be able to well quantify regional terrestrial carbon fluxes. However, combining the two modeling approaches and assimilating data of surface carbon flux as well as atmospheric CO2 mixing ratios might significantly improve the quantification of terrestrial carbon fluxes.

The Initial Atmospheric Transport (IAT) Code: Description and Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morrow, Charles W.; Bartel, Timothy James

The Initial Atmospheric Transport (IAT) computer code was developed at Sandia National Laboratories as part of their nuclear launch accident consequences analysis suite of computer codes. The purpose of IAT is to predict the initial puff/plume rise resulting from either a solid rocket propellant or liquid rocket fuel fire. The code generates initial conditions for subsequent atmospheric transport calculations. The Initial Atmospheric Transfer (IAT) code has been compared to two data sets which are appropriate to the design space of space launch accident analyses. The primary model uncertainties are the entrainment coefficients for the extended Taylor model. The Titan 34Dmore » accident (1986) was used to calibrate these entrainment settings for a prototypic liquid propellant accident while the recent Johns Hopkins University Applied Physics Laboratory (JHU/APL, or simply APL) large propellant block tests (2012) were used to calibrate the entrainment settings for prototypic solid propellant accidents. North American Meteorology (NAM )formatted weather data profiles are used by IAT to determine the local buoyancy force balance. The IAT comparisons for the APL solid propellant tests illustrate the sensitivity of the plume elevation to the weather profiles; that is, the weather profile is a dominant factor in determining the plume elevation. The IAT code performed remarkably well and is considered validated for neutral weather conditions.« less

ELF and ALEX SURF WINTER WAVES: Lidar Intercomparison of Aerosol and Water Vapor Measurements in the Baltimore-Washington Metropolitan Area During the Winter Water Vapor Validation Experiments (WAVES) 2008 campaign.

NASA Astrophysics Data System (ADS)

Delgado, R.; Weldegaber, M.; Wilson, R. C.; McMillan, W.; McCann, K. J.; Woodman, M.; Demoz, B.; Adam, M.; Connell, R.; Venable, D.; Joseph, E.; Rabenhorst, S.; Twigg, L.; McGee, T.; Whiteman, D. N.; Hoff, R. M.

2008-12-01

Elastic and Raman lidar measurements were conducted to measure the vertical distribution of aerosols and water vapor during the Water Vapor Validation Experiments (WAVES) 2008 campaign by the University of Maryland Baltimore County (UMBC) Atmospheric Lidar Group at UMBC, at the same time as measurements at Howard University's Beltsville Research Station (26.5 km distant). The lidar profiles of atmospheric water vapor and aerosols allowed comparison for AURA/Aqua retrieval studies, by performing instrument accuracy assessments and data, generated by various independent active and passive remote sensing instruments for case studies of regional water vapor and aerosol sub-pixel variability. Integration of the lidar water vapor mixing ratios has been carried out to generate a column precipitable water vapor timeseries that can be compared to UMBC's SUOMINET station and Baltimore Bomem Atmospheric Emitted Radiance Interferometer (BBAERI). Changes in atmospheric aerosol concentration and water vapor mixing ratios due to meteorological events observed in the lidar timeseries have been correlated to the vertical temperature timeseries of BBAERI and to modeling of the air mass over the Baltimore-Washington metro area with the Weather Research and Forecasting (WRF) model.

Space Weather Model Testing And Validation At The Community Coordinated Modeling Center

NASA Astrophysics Data System (ADS)

Hesse, M.; Kuznetsova, M.; Rastaetter, L.; Falasca, A.; Keller, K.; Reitan, P.

The Community Coordinated Modeling Center (CCMC) is a multi-agency partner- ship aimed at the creation of next generation space weather models. The goal of the CCMC is to undertake the research and developmental work necessary to substantially increase the present-day modeling capability for space weather purposes, and to pro- vide models for transition to the rapid prototyping centers at the space weather forecast centers. This goal requires close collaborations with and substantial involvement of the research community. The physical regions to be addressed by CCMC-related activities range from the solar atmosphere to the Earth's upper atmosphere. The CCMC is an integral part of NASA's Living With aStar initiative, of the National Space Weather Program Implementation Plan, and of the Department of Defense Space Weather Tran- sition Plan. CCMC includes a facility at NASA Goddard Space Flight Center, as well as distributed computing facilities provided by the Air Force. CCMC also provides, to the research community, access to state-of-the-art space research models. In this paper we will provide updates on CCMC status, on current plans, research and devel- opment accomplishments and goals, and on the model testing and validation process undertaken as part of the CCMC mandate.

Spectral relationships for atmospheric correction. I. Validation of red and near infra-red marine reflectance relationships.

PubMed

Goyens, C; Jamet, C; Ruddick, K G

2013-09-09

The present study provides an extensive overview of red and near infra-red (NIR) spectral relationships found in the literature and used to constrain red or NIR-modeling schemes in current atmospheric correction (AC) algorithms with the aim to improve water-leaving reflectance retrievals, ρw(λ), in turbid waters. However, most of these spectral relationships have been developed with restricted datasets and, subsequently, may not be globally valid, explaining the need of an accurate validation exercise. Spectral relationships are validated here with turbid in situ data for ρw(λ). Functions estimating ρw(λ) in the red were only valid for moderately turbid waters (ρw(λNIR) < 3.10(-3)). In contrast, bounding equations used to limit ρw(667) retrievals according to the water signal at 555 nm, appeared to be valid for all turbidity ranges presented in the in situ dataset. In the NIR region of the spectrum, the constant NIR reflectance ratio suggested by Ruddick et al. (2006) (Limnol. Oceanogr. 51, 1167-1179), was valid for moderately to very turbid waters (ρw(λNIR) < 10(-2)) while the polynomial function, initially developed by Wang et al. (2012) (Opt. Express 20, 741-753) with remote sensing reflectances over the Western Pacific, was also valid for extremely turbid waters (ρw(λNIR) > 10(-2)). The results of this study suggest to use the red bounding equations and the polynomial NIR function to constrain red or NIR-modeling schemes in AC processes with the aim to improve ρw(λ) retrievals where current AC algorithms fail.

Chemical Thermodynamics of Aqueous Atmospheric Aerosols: Modeling and Microfluidic Measurements

NASA Astrophysics Data System (ADS)

Nandy, L.; Dutcher, C. S.

2017-12-01

Accurate predictions of gas-liquid-solid equilibrium phase partitioning of atmospheric aerosols by thermodynamic modeling and measurements is critical for determining particle composition and internal structure at conditions relevant to the atmosphere. Organic acids that originate from biomass burning, and direct biogenic emission make up a significant fraction of the organic mass in atmospheric aerosol particles. In addition, inorganic compounds like ammonium sulfate and sea salt also exist in atmospheric aerosols, that results in a mixture of single, double or triple charged ions, and non-dissociated and partially dissociated organic acids. Statistical mechanics based on a multilayer adsorption isotherm model can be applied to these complex aqueous environments for predictions of thermodynamic properties. In this work, thermodynamic analytic predictive models are developed for multicomponent aqueous solutions (consisting of partially dissociating organic and inorganic acids, fully dissociating symmetric and asymmetric electrolytes, and neutral organic compounds) over the entire relative humidity range, that represent a significant advancement towards a fully predictive model. The model is also developed at varied temperatures for electrolytes and organic compounds the data for which are available at different temperatures. In addition to the modeling approach, water loss of multicomponent aerosol particles is measured by microfluidic experiments to parameterize and validate the model. In the experimental microfluidic measurements, atmospheric aerosol droplet chemical mimics (organic acids and secondary organic aerosol (SOA) samples) are generated in microfluidic channels and stored and imaged in passive traps until dehydration to study the influence of relative humidity and water loss on phase behavior.

Using machine learning to produce near surface soil moisture estimates from deeper in situ records at U.S. Climate Reference Network (USCRN) locations: Analysis and applications to AMSR-E satellite validation

USDA-ARS?s Scientific Manuscript database

Surface soil moisture is critical parameter for understanding the energy flux at the land atmosphere boundary. Weather modeling, climate prediction, and remote sensing validation are some of the applications for surface soil moisture information. The most common in situ measurement for these purpo...

Offshore Radiation Observations for Climate Research at the CERES Ocean Validation Experiment

NASA Technical Reports Server (NTRS)

Rutledge, Charles K.; Schuster, Gregory L.; Charlock, Thomas P.; Denn, Frederick M.; Smith, William L., Jr.; Fabbri, Bryan E.; Madigan, James J., Jr.; Knapp, Robert J.

2006-01-01

When radiometers on a satellite are pointed towards the planet with the goal of understanding a phenomenon quantitatively, rather than just creating a pleasing image, the task at hand is often problematic. The signal at the detector can be affected by scattering, absorption, and emission; and these can be due to atmospheric constituents (gases, clouds, and aerosols), the earth's surface, and subsurface features. When targeting surface phenomena, the remote sensing algorithm needs to account for the radiation associated with the atmospheric constituents. Likewise, one needs to correct for the radiation leaving the surface, when atmospheric phenomena are of interest. Rigorous validation of such remote sensing products is a real challenge. In visible and near infrared wavelengths, the jumble of effects on atmospheric radiation are best accomplished over dark surfaces with fairly uniform reflective properties (spatial homogeneity) in the satellite instrument's field of view (FOV). The ocean's surface meets this criteria; land surfaces - which are brighter, more spatially inhomogeneous, and more changeable with time - generally do not. NASA's Clouds and the Earth's Radiant Energy System (CERES) project has used this backdrop to establish a radiation monitoring site in Virginia's coastal Atlantic Ocean. The project, called the CERES Ocean Validation Experiment (COVE), is located on a rigid ocean platform allowing the accurate measurement of radiation parameters that require precise leveling and pointing unavailable from ships or buoys. The COVE site is an optimal location for verifying radiative transfer models and remote sensing algorithms used in climate research; because of the platform's small size, there are no island wake effects; and suites of sensors can be simultaneously trained both on the sky and directly on ocean itself. This paper describes the site, the types of measurements made, multiple years of atmospheric and ocean surface radiation observations, and satellite validation results.

Detection and modelling of the ionospheric perturbation caused by a Space Shuttle launch using a network of ground-based Global Positioning System stations

NASA Astrophysics Data System (ADS)

Bowling, Timothy; Calais, Eric; Haase, Jennifer S.

2013-03-01

The exhaust plume of the Space Shuttle during its ascent triggers acoustic waves which propagate through the atmosphere and induce electron density changes at ionospheric heights which changes can be measured using ground-based Global Positioning System (GPS) phase data. Here, we use a network of GPS stations to study the acoustic wave generated by the STS-125 Space Shuttle launch on May 11, 2009. We detect the resulting changes in ionospheric electron density, with characteristics that are typical of acoustic waves triggered by explosions at or near the Earth's surface or in the atmosphere. We successfully reproduce the amplitude and timing of the observed signal using a ray-tracing model with a moving source whose amplitude is directly scaled by a physical model of the shuttle exhaust energy, acoustic propagation in a dispersive atmosphere and a simplified two-fluid model of collisions between neutral gas and free electrons in the ionosphere. The close match between observed and model waveforms validates the modelling approach. This raises the possibility of using ground-based GPS networks to estimate the acoustic energy release of explosive sources near the Earth's surface or in atmosphere, and to constrain some atmospheric acoustic parameters.

Numerical simulation of "an American haboob"

NASA Astrophysics Data System (ADS)

Vukovic, A.; Vujadinovic, M.; Pejanovic, G.; Andric, J.; Kumjian, M. R.; Djurdjevic, V.; Dacic, M.; Prasad, A. K.; El-Askary, H. M.; Paris, B. C.; Petkovic, S.; Nickovic, S.; Sprigg, W. A.

2014-04-01

A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land-atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High-resolution numerical models are required for accurate simulation of the small scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran Desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME-DREAM (Non-hydrostatic Mesoscale Model on E grid, Janjic et al., 2001; Dust REgional Atmospheric Model, Nickovic et al., 2001; Pérez et al., 2006) with 4 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The scope of this paper is validation of the dust model performance, and not use of the model as a tool to investigate mechanisms related to the storm. Results demonstrate the potential technical capacity and availability of the relevant data to build an operational system for dust storm forecasting as a part of a warning system. Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~25 km), the model PM10 surface dust concentration reached ~2500 μg m-3, but underestimated the values measured by the PM10 stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.

Validation of a weather forecast model at radiance level against satellite observations allowing quantification of temperature, humidity, and cloud-related biases

NASA Astrophysics Data System (ADS)

Bani Shahabadi, Maziar; Huang, Yi; Garand, Louis; Heilliette, Sylvain; Yang, Ping

2016-09-01

An established radiative transfer model (RTM) is adapted for simulating all-sky infrared radiance spectra from the Canadian Global Environmental Multiscale (GEM) model in order to validate its forecasts at the radiance level against Atmospheric InfraRed Sounder (AIRS) observations. Synthetic spectra are generated for 2 months from short-term (3-9 h) GEM forecasts. The RTM uses a monthly climatological land surface emissivity/reflectivity atlas. An updated ice particle optical property library was introduced for cloudy radiance calculations. Forward model brightness temperature (BT) biases are assessed to be of the order of ˜1 K for both clear-sky and overcast conditions. To quantify GEM forecast meteorological variables biases, spectral sensitivity kernels are generated and used to attribute radiance biases to surface and atmospheric temperatures, atmospheric humidity, and clouds biases. The kernel method, supplemented with retrieved profiles based on AIRS observations in collocation with a microwave sounder, achieves good closure in explaining clear-sky radiance biases, which are attributed mostly to surface temperature and upper tropospheric water vapor biases. Cloudy-sky radiance biases are dominated by cloud-induced radiance biases. Prominent GEM biases are identified as: (1) too low surface temperature over land, causing about -5 K bias in the atmospheric window region; (2) too high upper tropospheric water vapor, inducing about -3 K bias in the water vapor absorption band; (3) too few high clouds in the convective regions, generating about +10 K bias in window band and about +6 K bias in the water vapor band.

Atmospheric Research 2016 Technical Highlights

NASA Technical Reports Server (NTRS)

Platnick, Steven

2017-01-01

Atmospheric research in the Earth Sciences Division (610) consists of research and technology development programs dedicated to advancing knowledge and understanding of the atmosphere and its interaction with the climate of Earth. The Divisions goals are to improve understanding of the dynamics and physical properties of precipitation, clouds, and aerosols; atmospheric chemistry, including the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and radiative properties of Earth's atmosphere and the influence of solar variability on the Earth's climate. Major research activities are carried out in the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office. The overall scope of the research covers an end-to-end process, starting with the identification of scientific problems, leading to observation requirements for remote-sensing platforms, technology and retrieval algorithm development; followed by flight projects and satellite missions; and eventually, resulting in data processing, analyses of measurements, and dissemination from flight projects and missions. Instrument scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology to remotely sense the atmosphere. Members of the various laboratories conduct field measurements for satellite sensor calibration and data validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud resolving models, and developing the next-generation Earth system models. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential at every stage of the research process to meeting our goals and maintaining leadership of the Earth Sciences Division in atmospheric science research. Figure 1.1 shows the 22-year record of peer-reviewed publications and proposals among the various laboratories.

Experimental validation of the MODTRAN 5.3 sea surface radiance model using MIRAMER campaign measurements.

PubMed

Ross, Vincent; Dion, Denis; St-Germain, Daniel

2012-05-01

Radiometric images taken in mid-wave and long-wave infrared bands are used as a basis for validating a sea surface bidirectional reflectance distribution function (BRDF) being implemented into MODTRAN 5 (Berk et al. [Proc. SPIE5806, 662 (2005)]). The images were obtained during the MIRAMER campaign that took place in May 2008 in the Mediterranean Sea near Toulon, France. When atmosphere radiances are matched at the horizon to remove possible calibration offsets, the implementation of the BRDF in MODTRAN produces good sea surface radiance agreement, usually within 2% and at worst 4% from off-glint azimuthally averaged measurements. Simulations also compare quite favorably to glint measurements. The observed sea radiance deviations between model and measurements are not systematic, and are well within expected experimental uncertainties. This is largely attributed to proper radiative coupling between the surface and the atmosphere implemented using the DISORT multiple scattering algorithm.

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Way, M. J.; Aleinov, I.; Amundsen, David S.

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower tomore » more rapid than modern Earth’s, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn’s moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.« less

Photochemistry in Terrestrial Exoplanet Atmospheres. I. Photochemistry Model and Benchmark Cases

NASA Astrophysics Data System (ADS)

Hu, Renyu; Seager, Sara; Bains, William

2012-12-01

We present a comprehensive photochemistry model for exploration of the chemical composition of terrestrial exoplanet atmospheres. The photochemistry model is designed from the ground up to have the capacity to treat all types of terrestrial planet atmospheres, ranging from oxidizing through reducing, which makes the code suitable for applications for the wide range of anticipated terrestrial exoplanet compositions. The one-dimensional chemical transport model treats up to 800 chemical reactions, photochemical processes, dry and wet deposition, surface emission, and thermal escape of O, H, C, N, and S bearing species, as well as formation and deposition of elemental sulfur and sulfuric acid aerosols. We validate the model by computing the atmospheric composition of current Earth and Mars and find agreement with observations of major trace gases in Earth's and Mars' atmospheres. We simulate several plausible atmospheric scenarios of terrestrial exoplanets and choose three benchmark cases for atmospheres from reducing to oxidizing. The most interesting finding is that atomic hydrogen is always a more abundant reactive radical than the hydroxyl radical in anoxic atmospheres. Whether atomic hydrogen is the most important removal path for a molecule of interest also depends on the relevant reaction rates. We also find that volcanic carbon compounds (i.e., CH4 and CO2) are chemically long-lived and tend to be well mixed in both reducing and oxidizing atmospheres, and their dry deposition velocities to the surface control the atmospheric oxidation states. Furthermore, we revisit whether photochemically produced oxygen can cause false positives for detecting oxygenic photosynthesis, and find that in 1 bar CO2-rich atmospheres oxygen and ozone may build up to levels that have conventionally been accepted as signatures of life, if there is no surface emission of reducing gases. The atmospheric scenarios presented in this paper can serve as the benchmark atmospheres for quickly assessing the lifetime of trace gases in reducing, weakly oxidizing, and highly oxidizing atmospheres on terrestrial exoplanets for the exploration of possible biosignature gases.

Performance of a reconfigured atmospheric general circulation model at low resolution

NASA Astrophysics Data System (ADS)

Wen, Xinyu; Zhou, Tianjun; Wang, Shaowu; Wang, Bin; Wan, Hui; Li, Jian

2007-07-01

Paleoclimate simulations usually require model runs over a very long time. The fast integration version of a state-of-the-art general circulation model (GCM), which shares the same physical and dynamical processes but with reduced horizontal resolution and increased time step, is usually developed. In this study, we configure a fast version of an atmospheric GCM (AGCM), the Grid Atmospheric Model of IAP/LASG (Institute of Atmospheric Physics/State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics), at low resolution (GAMIL-L, hereafter), and compare the simulation results with the NCEP/NCAR reanalysis and other data to examine its performance. GAMIL-L, which is derived from the original GAMIL, is a finite difference AGCM with 72×40 grids in longitude and latitude and 26 vertical levels. To validate the simulated climatology and variability, two runs were achieved. One was a 60-year control run with fixed climatological monthly sea surface temperature (SST) forcing, and the other was a 50-yr (1950 2000) integration with observational time-varying monthly SST forcing. Comparisons between these two cases and the reanalysis, including intra-seasonal and inter-annual variability are also presented. In addition, the differences between GAMIL-L and the original version of GAMIL are also investigated. The results show that GAMIL-L can capture most of the large-scale dynamical features of the atmosphere, especially in the tropics and mid latitudes, although a few deficiencies exist, such as the underestimated Hadley cell and thereby the weak strength of the Asia summer monsoon. However, the simulated mean states over high latitudes, especially over the polar regions, are not acceptable. Apart from dynamics, the thermodynamic features mainly depend upon the physical parameterization schemes. Since the physical package of GAMIL-L is exactly the same as the original high-resolution version of GAMIL, in which the NCAR Community Atmosphere Model (CAM2) physical package was used, there are only small differences between them in the precipitation and temperature fields. Because our goal is to develop a fast-running AGCM and employ it in the coupled climate system model of IAP/LASG for paleoclimate studies such as ENSO and Australia-Asia monsoon, particular attention has been paid to the model performances in the tropics. More model validations, such as those ran for the Southern Oscillation and South Asia monsoon, indicate that GAMIL-L is reasonably competent and valuable in this regard.

NAIRAS aircraft radiation model development, dose climatology, and initial validation.

PubMed

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-10-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

NAIRAS aircraft radiation model development, dose climatology, and initial validation

NASA Astrophysics Data System (ADS)

Mertens, Christopher J.; Meier, Matthias M.; Brown, Steven; Norman, Ryan B.; Xu, Xiaojing

2013-10-01

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

NAIRAS aircraft radiation model development, dose climatology, and initial validation

PubMed Central

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-01-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway. PMID:26213513

Transmission spectroscopy with the ACE-FTS infrared spectral atlas of Earth: A model validation and feasibility study

NASA Astrophysics Data System (ADS)

Schreier, Franz; Städt, Steffen; Hedelt, Pascal; Godolt, Mareike

2018-06-01

Infrared solar occultation measurements are well established for remote sensing of Earth's atmosphere, and the corresponding primary transit spectroscopy has turned out to be valuable for characterization of extrasolar planets. Our objective is an assessment of the detectability of molecular signatures in Earth's transit spectra. To this end, we take a limb sequence of representative cloud-free transmission spectra recorded by the space-borne ACE-FTS Earth observation mission (Hughes et al., ACE infrared spectral atlases of the Earth's atmosphere, JQSRT 2014) and combine these spectra to the effective height of the atmosphere. These data are compared to spectra modeled with an atmospheric radiative transfer line-by-line infrared code to study the impact of individual molecules, spectral resolution, the choice of auxiliary data, and numerical approximations. Moreover, the study serves as a validation of our infrared radiative transfer code. The largest impact is due to water, carbon dioxide, ozone, methane, nitrous oxide, nitrogen, nitric acid, oxygen, and some chlorofluorocarbons (CFC11 and CFC12). The effect of further molecules considered in the modeling is either marginal or absent. The best matching model has a mean residuum of 0.4 km and a maximum difference of 2 km to the measured effective height. For a quantitative estimate of visibility and detectability we consider the maximum change of the residual spectrum, the relative change of the residual norm, the additional transit depth, and signal-to-noise ratios for a JWST setup. In conclusion, our study provides a list of molecules that are relevant for modeling transmission spectra of Earth-like exoplanets and discusses the feasibility of retrieval.

The vector radiative transfer numerical model of coupled ocean-atmosphere system using the matrix-operator method

NASA Astrophysics Data System (ADS)

Xianqiang, He; Delu, Pan; Yan, Bai; Qiankun, Zhu

2005-10-01

The numerical model of the vector radiative transfer of the coupled ocean-atmosphere system is developed based on the matrix-operator method, which is named PCOART. In PCOART, using the Fourier analysis, the vector radiative transfer equation (VRTE) splits up into a set of independent equations with zenith angle as only angular coordinate. Using the Gaussian-Quadrature method, VRTE is finally transferred into the matrix equation, which is calculated by using the adding-doubling method. According to the reflective and refractive properties of the ocean-atmosphere interface, the vector radiative transfer numerical model of ocean and atmosphere is coupled in PCOART. By comparing with the exact Rayleigh scattering look-up-table of MODIS(Moderate-resolution Imaging Spectroradiometer), it is shown that PCOART is an exact numerical calculation model, and the processing methods of the multi-scattering and polarization are correct in PCOART. Also, by validating with the standard problems of the radiative transfer in water, it is shown that PCOART could be used to calculate the underwater radiative transfer problems. Therefore, PCOART is a useful tool to exactly calculate the vector radiative transfer of the coupled ocean-atmosphere system, which can be used to study the polarization properties of the radiance in the whole ocean-atmosphere system and the remote sensing of the atmosphere and ocean.

High Vertically Resolved Atmospheric and Surface/Cloud Parameters Retrieved with Infrared Atmospheric Sounding Interferometer (IASI)

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, WIlliam L.; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Stephen A.

2008-01-01

The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25/cm and a spectral coverage from 645 to 2760/cm. Ultra-spectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. This physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the cloud-free and/or clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multi-variable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. It is shown that relatively accurate temperature and moisture retrievals are achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with relatively high accuracy (i.e., error < 1 km). Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations are obtained and presented. These retrievals will be further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed - Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated indicating a high vertical structure of atmosphere is retrieved.

Exploring Hot Exoplanet Atmospheres with JWST/NIRSpec and a Hybrid Version of NEMESIS

NASA Astrophysics Data System (ADS)

Badhan, Mahmuda A.; Mandell, Avi; Batalha, Natasha; Irwin, Patrick GJ; Barstow, Joanna; Garland, Ryan; Deming, Drake; Hesman, Brigette E.; Nixon, Conor A.

2016-01-01

Understanding the formation environments and evolution scenarios of hot Jupiters demands robust measures for constraining their atmospheric physical properties and transit observations at unprecedented resolutions. Here we have utilized a combination of two different approaches, Optimal Estimation (OE) and Markov Chain Monte Carlo (MCMC), as part of the extensively validated NEMESIS atmospheric retrieval code, to infer pressure-temperature (P-T) profiles & gas mixing ratios (VMR) of H2O, CO2, CH4 and CO, from a series of tests conducted on JWST/NIRSpec simulations of the dayside thermal emission spectra (secondary eclipse) of H2-dominated hot-Jupiter candidates. To keep the number of parameters low and henceforth retrieve more plausible profile shapes, we have used a parametrized form of the temperature profile based upon the analytic radiative equilibrium derivation in Guillot et al. 2010. For the purpose of testing and validation, we also show some preliminary work on published dataset from the Hubble Space Telescope (HST) and Spitzer missions. Finally, high-temperature (T> 1000K) spectroscopic line lists are slowly but continually being improved by the atmospheric retrieval community. Since this carries the potential of impacting hot Jupiter atmospheric models quite significantly, we compare results from different databases.

Estimates of the atmospheric parameters of M-type stars: a machine-learning perspective

NASA Astrophysics Data System (ADS)

Sarro, L. M.; Ordieres-Meré, J.; Bello-García, A.; González-Marcos, A.; Solano, E.

2018-05-01

Estimating the atmospheric parameters of M-type stars has been a difficult task due to the lack of simple diagnostics in the stellar spectra. We aim at uncovering good sets of predictive features of stellar atmospheric parameters (Teff, log (g), [M/H]) in spectra of M-type stars. We define two types of potential features (equivalent widths and integrated flux ratios) able to explain the atmospheric physical parameters. We search the space of feature sets using a genetic algorithm that evaluates solutions by their prediction performance in the framework of the BT-Settl library of stellar spectra. Thereafter, we construct eight regression models using different machine-learning techniques and compare their performances with those obtained using the classical χ2 approach and independent component analysis (ICA) coefficients. Finally, we validate the various alternatives using two sets of real spectra from the NASA Infrared Telescope Facility (IRTF) and Dwarf Archives collections. We find that the cross-validation errors are poor measures of the performance of regression models in the context of physical parameter prediction in M-type stars. For R ˜ 2000 spectra with signal-to-noise ratios typical of the IRTF and Dwarf Archives, feature selection with genetic algorithms or alternative techniques produces only marginal advantages with respect to representation spaces that are unconstrained in wavelength (full spectrum or ICA). We make available the atmospheric parameters for the two collections of observed spectra as online material.

Flight Data Reduction of Wake Velocity Measurements Using an Instrumented OV-10 Airplane

NASA Technical Reports Server (NTRS)

Vicroy, Dan D.; Stuever, Robert A.; Stewart, Eric C.; Rivers, Robert A.

1999-01-01

A series of flight tests to measure the wake of a Lockheed C- 130 airplane and the accompanying atmospheric state have been conducted. A specially instrumented North American Rockwell OV-10 airplane was used to measure the wake and atmospheric conditions. An integrated database has been compiled for wake characterization and validation of wake vortex computational models. This paper describes the wake- measurement flight-data reduction process.

Thermal Diagnostics with the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions

NASA Astrophysics Data System (ADS)

Cheung, Mark C. M.; Boerner, P.; Schrijver, C. J.; Testa, P.; Chen, F.; Peter, H.; Malanushenko, A.

2015-07-01

We present a new method for performing differential emission measure (DEM) inversions on narrow-band EUV images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. The method yields positive definite DEM solutions by solving a linear program. This method has been validated against a diverse set of thermal models of varying complexity and realism. These include (1) idealized Gaussian DEM distributions, (2) 3D models of NOAA Active Region 11158 comprising quasi-steady loop atmospheres in a nonlinear force-free field, and (3) thermodynamic models from a fully compressible, 3D MHD simulation of active region (AR) corona formation following magnetic flux emergence. We then present results from the application of the method to AIA observations of Active Region 11158, comparing the region's thermal structure on two successive solar rotations. Additionally, we show how the DEM inversion method can be adapted to simultaneously invert AIA and Hinode X-ray Telescope data, and how supplementing AIA data with the latter improves the inversion result. The speed of the method allows for routine production of DEM maps, thus facilitating science studies that require tracking of the thermal structure of the solar corona in time and space.

THERMAL DIAGNOSTICS WITH THE ATMOSPHERIC IMAGING ASSEMBLY ON BOARD THE SOLAR DYNAMICS OBSERVATORY: A VALIDATED METHOD FOR DIFFERENTIAL EMISSION MEASURE INVERSIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Mark C. M.; Boerner, P.; Schrijver, C. J.

We present a new method for performing differential emission measure (DEM) inversions on narrow-band EUV images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. The method yields positive definite DEM solutions by solving a linear program. This method has been validated against a diverse set of thermal models of varying complexity and realism. These include (1) idealized Gaussian DEM distributions, (2) 3D models of NOAA Active Region 11158 comprising quasi-steady loop atmospheres in a nonlinear force-free field, and (3) thermodynamic models from a fully compressible, 3D MHD simulation of active region (AR) corona formation following magneticmore » flux emergence. We then present results from the application of the method to AIA observations of Active Region 11158, comparing the region's thermal structure on two successive solar rotations. Additionally, we show how the DEM inversion method can be adapted to simultaneously invert AIA and Hinode X-ray Telescope data, and how supplementing AIA data with the latter improves the inversion result. The speed of the method allows for routine production of DEM maps, thus facilitating science studies that require tracking of the thermal structure of the solar corona in time and space.« less

Variational Iterative Refinement Source Term Estimation Algorithm Assessment for Rural and Urban Environments

NASA Astrophysics Data System (ADS)

Delle Monache, L.; Rodriguez, L. M.; Meech, S.; Hahn, D.; Betancourt, T.; Steinhoff, D.

2016-12-01

It is necessary to accurately estimate the initial source characteristics in the event of an accidental or intentional release of a Chemical, Biological, Radiological, or Nuclear (CBRN) agent into the atmosphere. The accurate estimation of the source characteristics are important because many times they are unknown and the Atmospheric Transport and Dispersion (AT&D) models rely heavily on these estimates to create hazard assessments. To correctly assess the source characteristics in an operational environment where time is critical, the National Center for Atmospheric Research (NCAR) has developed a Source Term Estimation (STE) method, known as the Variational Iterative Refinement STE algorithm (VIRSA). VIRSA consists of a combination of modeling systems. These systems include an AT&D model, its corresponding STE model, a Hybrid Lagrangian-Eulerian Plume Model (H-LEPM), and its mathematical adjoint model. In an operational scenario where we have information regarding the infrastructure of a city, the AT&D model used is the Urban Dispersion Model (UDM) and when using this model in VIRSA we refer to the system as uVIRSA. In all other scenarios where we do not have the city infrastructure information readily available, the AT&D model used is the Second-order Closure Integrated PUFF model (SCIPUFF) and the system is referred to as sVIRSA. VIRSA was originally developed using SCIPUFF 2.4 for the Defense Threat Reduction Agency and integrated into the Hazard Prediction and Assessment Capability and Joint Program for Information Systems Joint Effects Model. The results discussed here are the verification and validation of the upgraded system with SCIPUFF 3.0 and the newly implemented UDM capability. To verify uVIRSA and sVIRSA, synthetic concentration observation scenarios were created in urban and rural environments and the results of this verification are shown. Finally, we validate the STE performance of uVIRSA using scenarios from the Joint Urban 2003 (JU03) experiment, which was held in Oklahoma City and also validate the performance of sVIRSA using scenarios from the FUsing Sensor Integrated Observing Network (FUSION) Field Trial 2007 (FFT07), held at Dugway Proving Grounds in rural Utah.

Air Quality Response Modeling for Decision Support | Science ...

EPA Pesticide Factsheets

Air quality management relies on photochemical models to predict the responses of pollutant concentrations to changes in emissions. Such modeling is especially important for secondary pollutants such as ozone and fine particulate matter which vary nonlinearly with changes in emissions. Numerous techniques for probing pollutant-emission relationships within photochemical models have been developed and deployed for a variety of decision support applications. However, atmospheric response modeling remains complicated by the challenge of validating sensitivity results against observable data. This manuscript reviews the state of the science of atmospheric response modeling as well as efforts to characterize the accuracy and uncertainty of sensitivity results. The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being use

Simulations of Variability and Waves at Cloud Altitudes Using a Venus Middle Atmosphere General Circulation Model

NASA Astrophysics Data System (ADS)

Parish, H. F.; Mitchell, J.

2017-12-01

We have developed a Venus general circulation model, the Venus Middle atmosphere Model (VMM), to simulate the atmosphere from just below the cloud deck 40 km altitude to around 100 km altitude. Our primary goal is to assess the influence of waves on the variability of winds and temperatures observed around Venus' cloud deck. Venus' deep atmosphere is not simulated directly in the VMM model, so the effects of waves propagating upwards from the lower atmosphere is represented by forcing at the lower boundary of the model. Sensitivity tests allow appropriate amplitudes for the wave forcing to be determined by comparison with Venus Express and probe measurements and allow the influence of waves on the cloud-level atmosphere to be investigated. Observations at cloud altitudes are characterized by waves with a wide variety of periods and wavelengths, including gravity waves, thermal tides, Rossby waves, and Kelvin waves. These waves may be generated within the cloud deck by instabilities, or may propagate up from the deep atmosphere. Our development of the VMM is motivated by the fact that the circulation and dynamics between the surface and the cloud levels are not well measured and wind velocities below 40 km altitude cannot be observed remotely, so we focus on the dynamics at cloud levels and above. Initial results from the VMM with a simplified radiation scheme have been validated by comparison with Pioneer Venus and Venus Express observations and show reasonable agreement with the measurements.

The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

NASA Astrophysics Data System (ADS)

Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

2016-06-01

Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

Cloud cover determination in polar regions from satellite imagery

NASA Technical Reports Server (NTRS)

Barry, R. G.; Key, J. R.; Maslanik, J. A.

1988-01-01

The principal objectives of this project are: (1) to develop suitable validation data sets to evaluate the effectiveness of the International Satellite Cloud Climatology Project (ISCCP) operational algorithm for cloud retrieval in polar regions and to validate model simulations of polar cloud cover; (2) to identify limitations of current procedures for varying atmospheric surface conditions, and to explore potential means to remedy them using textural classifiers; and (3) to compare synoptic cloud data from a control run experiment of the GISS climate model II with typical observed synoptic cloud patterns.

Evaluating Galactic Cosmic Ray Environment Models Using RaD-X Flight Data

NASA Technical Reports Server (NTRS)

Norman, R. B.; Mertens, C. J.; Slaba, T. C.

2016-01-01

Galactic cosmic rays enter Earth's atmosphere after interacting with the geomagnetic field. The primary galactic cosmic rays spectrum is fundamentally changed as it interacts with Earth's atmosphere through nuclear and atomic interactions. At points deeper in the atmosphere, such as at airline altitudes, the radiation environment is a combination of the primary galactic cosmic rays and the secondary particles produced through nuclear interactions. The RaD-X balloon experiment measured the atmospheric radiation environment above 20 km during 2 days in September 2015. These experimental measurements were used to validate and quantify uncertainty in physics-based models used to calculate exposure levels for commercial aviation. In this paper, the Badhwar-O'Neill 2014, the International Organization for Standardization 15390, and the German Aerospace Company galactic cosmic ray environment models are used as input into the same radiation transport code to predict and compare dosimetric quantities to RaD-X measurements. In general, the various model results match the measured tissue equivalent dose well, with results generated by the German Aerospace Center galactic cosmic ray environment model providing the best comparison. For dose equivalent and dose measured in silicon, however, the models were compared less favorably to the measurements.

Data Processing for Atmospheric Phase Interferometers

NASA Technical Reports Server (NTRS)

Acosta, Roberto J.; Nessel, James A.; Morabito, David D.

2009-01-01

This paper presents a detailed discussion of calibration procedures used to analyze data recorded from a two-element atmospheric phase interferometer (API) deployed at Goldstone, California. In addition, we describe the data products derived from those measurements that can be used for site intercomparison and atmospheric modeling. Simulated data is used to demonstrate the effectiveness of the proposed algorithm and as a means for validating our procedure. A study of the effect of block size filtering is presented to justify our process for isolating atmospheric fluctuation phenomena from other system-induced effects (e.g., satellite motion, thermal drift). A simulated 24 hr interferometer phase data time series is analyzed to illustrate the step-by-step calibration procedure and desired data products.

The dynamical core of the Aeolus 1.0 statistical-dynamical atmosphere model: validation and parameter optimization

NASA Astrophysics Data System (ADS)

Totz, Sonja; Eliseev, Alexey V.; Petri, Stefan; Flechsig, Michael; Caesar, Levke; Petoukhov, Vladimir; Coumou, Dim

2018-02-01

We present and validate a set of equations for representing the atmosphere's large-scale general circulation in an Earth system model of intermediate complexity (EMIC). These dynamical equations have been implemented in Aeolus 1.0, which is a statistical-dynamical atmosphere model (SDAM) and includes radiative transfer and cloud modules (Coumou et al., 2011; Eliseev et al., 2013). The statistical dynamical approach is computationally efficient and thus enables us to perform climate simulations at multimillennia timescales, which is a prime aim of our model development. Further, this computational efficiency enables us to scan large and high-dimensional parameter space to tune the model parameters, e.g., for sensitivity studies.Here, we present novel equations for the large-scale zonal-mean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0.We optimize the dynamical core parameter values by tuning all relevant dynamical fields to ERA-Interim reanalysis data (1983-2009) forcing the dynamical core with prescribed surface temperature, surface humidity and cumulus cloud fraction. We test the model's performance in reproducing the seasonal cycle and the influence of the El Niño-Southern Oscillation (ENSO). We use a simulated annealing optimization algorithm, which approximates the global minimum of a high-dimensional function.With non-tuned parameter values, the model performs reasonably in terms of its representation of zonal-mean circulation, planetary waves and storm tracks. The simulated annealing optimization improves in particular the model's representation of the Northern Hemisphere jet stream and storm tracks as well as the Hadley circulation.The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications.

GNSS-Based Space Weather Systems Including COSMIC Ionospheric Measurements

NASA Technical Reports Server (NTRS)

Komjathy, Attila; Mandrake, Lukas; Wilson, Brian; Iijima, Byron; Pi, Xiaoqing; Hajj, George; Mannucci, Anthony J.

2006-01-01

The presentation outline includes University Corporation for Atmospheric Research (UCAR) and Jet Propulsion Laboratory (JPL) product comparisons, assimilating ground-based global positioning satellites (GPS) and COSMIC into JPL/University of Southern California (USC) Global Assimilative Ionospheric Model (GAIM), and JPL/USC GAIM validation. The discussion of comparisons examines Abel profiles and calibrated TEC. The JPL/USC GAIM validation uses Arecibo ISR, Jason-2 VTEC, and Abel profiles.

The 2006 Cape Canaveral Air Force Station Range Reference Atmosphere Model Validation Study and Sensitivity Analysis to the National Aeronautics and Space Administration's Space Shuttle

NASA Technical Reports Server (NTRS)

Decker, Ryan K.; Burns, Lee; Merry, Carl; Harrington, Brian

2008-01-01

Atmospheric parameters are essential in assessing the flight performance of aerospace vehicles. The effects of the Earth's atmosphere on aerospace vehicles influence various aspects of the vehicle during ascent ranging from its flight trajectory to the structural dynamics and aerodynamic heatmg on the vehicle. Atmospheric databases charactenzing the wind and thermodynamic environments, known as Range Reference Atmospheres (RRA), have been developed at space launch ranges by a governmental interagency working group for use by aerospace vehicle programs. The National Aeronantics and Space Administration's (NASA) Space Shuttle Program (SSP), which launches from Kennedy Space Center, utilizes atmosphenc statistics derived from the Cape Canaveral Air Force Station Range Reference Atmosphere (CCAFS RRA) database to evaluate environmental constraints on various aspects of the vehlcle during ascent.

Impact of large-scale atmospheric refractive structures on optical wave propagation

NASA Astrophysics Data System (ADS)

Nunalee, Christopher G.; He, Ping; Basu, Sukanta; Vorontsov, Mikhail A.; Fiorino, Steven T.

2014-10-01

Conventional techniques used to model optical wave propagation through the Earth's atmosphere typically as- sume flow fields based on various empirical relationships. Unfortunately, these synthetic refractive index fields do not take into account the influence of transient macroscale and mesoscale (i.e. larger than turbulent microscale) atmospheric phenomena. Nevertheless, a number of atmospheric structures that are characterized by various spatial and temporal scales exist which have the potential to significantly impact refractive index fields, thereby resulting dramatic impacts on optical wave propagation characteristics. In this paper, we analyze a subset of spatio-temporal dynamics found to strongly affect optical waves propagating through these atmospheric struc- tures. Analysis of wave propagation was performed in the geometrical optics approximation using a standard ray tracing technique. Using a numerical weather prediction (NWP) approach, we simulate multiple realistic atmospheric events (e.g., island wakes, low-level jets, etc.), and estimate the associated refractivity fields prior to performing ray tracing simulations. By coupling NWP model output with ray tracing simulations, we demon- strate the ability to quantitatively assess the potential impacts of coherent atmospheric phenomena on optical ray propagation. Our results show a strong impact of spatio-temporal characteristics of the refractive index field on optical ray trajectories. Such correlations validate the effectiveness of NWP models as they offer a more comprehensive representation of atmospheric refractivity fields compared to conventional methods based on the assumption of horizontal homogeneity.

Space Weather Modeling Services at the Community Coordinated Modeling Center

NASA Technical Reports Server (NTRS)

Hesse, Michael

2006-01-01

The Community Coordinated Modeling Center (CCMC) is a multi-agency partnership, which aims at the creation of next generation space weather models. The goal of the CCMC is to support the research and developmental work necessary to substantially increase the present-day modeling capability for space weather purposes, and to provide models for transition to the Rapid Prototyping Centers at the space weather forecast centers. This goal requires close collaborations with and substantial involvement of the research community. The physical regions to be addressed by CCMC-related activities range from the solar atmosphere to the Earth's upper atmosphere. The CCMC is an integral part of the National Space Weather Program Implementation Plan, of NASA's Living With a Star (LWS) initiative, and of the Department of Defense Space Weather Transition Plan. CCMC includes a facility at NASA Goddard Space Flight Center. CCMC also provides, to the research community, access to state-of-the-art space research models. In this paper we will provide a description of the current CCMC status, discuss current plans, research and development accomplishments and goals, and describe the model testing and validation process undertaken as part of the CCMC mandate. Special emphasis will be on solar and heliospheric models currently residing at CCMC, and on plans for validation and verification.

Space Weather Modeling at the Community Coordinated Modeling Center

NASA Technical Reports Server (NTRS)

Hesse M.

2005-01-01

The Community Coordinated Modeling Center (CCMC) is a multi-agency partnership, which aims at the creation of next generation space weather models. The goal of the CCMC is to support the research and developmental work necessary to substantially increase the present-day modeling capability for space weather purposes, and to provide models for transition to the rapid prototyping centers at the space weather forecast centers. This goal requires dose collaborations with and substantial involvement of the research community. The physical regions to be addressed by CCMC-related activities range from the solar atmosphere to the Earth's upper atmosphere. The CCMC is an integral part of the National Space Weather Program Implementation Plan, of NASA's Living With a Star (LWS) initiative, and of the Department of Defense Space Weather Transition Plan. CCMC includes a facility at NASA Goddard Space Flight Center, as well as distributed computing facilities provided by the US Air Force. CCMC also provides, to the research community, access to state-of-the-art space research models. In this paper we will provide updates on CCMC status, on current plans, research and development accomplishments and goals, and on the model testing and validation process undertaken as part of the CCMC mandate. Special emphasis will be on solar and heliospheric models currently residing at CCMC, and on plans for validation and verification.

WRF Model Simulations of Terrain-Driven Atmospheric Eddies in Marine Stratocumulus Clouds

NASA Astrophysics Data System (ADS)

Muller, B. M.; Herbster, C. G.; Mosher, F. R.

2014-12-01

It is not unusual to observe atmospheric eddies in satellite imagery of the marine stratus and stratocumulus clouds that characterize the summertime weather of the California coastal region and near-shore oceanic environment. The winds of the marine atmospheric boundary layer (MABL) over the ocean interact with the high terrain of prominent headlands and islands to create order-10 km scale areas of swirling air that can contain a cloud-free eye, 180-degree wind reversals at the surface over a period of minutes, and may be associated with mixing and turbulence between the high-humidity air of the MABL and the much warmer and drier inversion layer air above. However, synoptic and even subsynoptic surface weather measurements, and the synoptic upper-air observing network are inadequate, or in some cases, completely unable, to detect and characterize the formation, movement, and even the existence of the eddies. They can literally slip between land-based surface observation locations, or stay over the near-shore ocean environment where there may be no surface meteorological measurements. This study presents Weather Research and Forecasting (WRF) Model simulations of these small-scale, terrain-driven, atmospheric features in the MABL from cases detected in GOES satellite imagery. The purpose is to use model output to diagnose the formation mechanisms, sources of vorticity, and the air flow in and around the eddies. Satellite imagery is compared to simulated atmospheric variables to validate features generated within the model atmosphere, and model output is employed as a surrogate atmosphere to better understand the atmospheric characteristics of the eddies. Model air parcel trajectories are estimated to trace the movement and sources of the air contained in and around these often-observed, but seldom-measured features.

Global Carbon Cycle Modeling in GISS ModelE2 GCM

NASA Astrophysics Data System (ADS)

Aleinov, I. D.; Kiang, N. Y.; Romanou, A.; Romanski, J.

2014-12-01

Consistent and accurate modeling of the Global Carbon Cycle remains one of the main challenges for the Earth System Models. NASA Goddard Institute for Space Studies (GISS) ModelE2 General Circulation Model (GCM) was recently equipped with a complete Global Carbon Cycle algorithm, consisting of three integrated components: Ent Terrestrial Biosphere Model (Ent TBM), Ocean Biogeochemistry Module and atmospheric CO2 tracer. Ent TBM provides CO2 fluxes from the land surface to the atmosphere. Its biophysics utilizes the well-known photosynthesis functions of Farqhuar, von Caemmerer, and Berry and Farqhuar and von Caemmerer, and stomatal conductance of Ball and Berry. Its phenology is based on temperature, drought, and radiation fluxes, and growth is controlled via allocation of carbon from labile carbohydrate reserve storage to different plant components. Soil biogeochemistry is based on the Carnegie-Ames-Stanford (CASA) model of Potter et al. Ocean biogeochemistry module (the NASA Ocean Biogeochemistry Model, NOBM), computes prognostic distributions for biotic and abiotic fields that influence the air-sea flux of CO2 and the deep ocean carbon transport and storage. Atmospheric CO2 is advected with a quadratic upstream algorithm implemented in atmospheric part of ModelE2. Here we present the results for pre-industrial equilibrium and modern transient simulations and provide comparison to available observations. We also discuss the process of validation and tuning of particular algorithms used in the model.

Optimized method for atmospheric signal reduction in irregular sampled InSAR time series assisted by external atmospheric information

NASA Astrophysics Data System (ADS)

Gong, W.; Meyer, F. J.

2013-12-01

It is well known that spatio-temporal the tropospheric phase signatures complicate the interpretation and detection of smaller magnitude deformation signals or unstudied motion fields. Several advanced time-series InSAR techniques were developed in the last decade that make assumptions about the stochastic properties of the signal components in interferometric phases to reduce atmospheric delay effects on surface deformation estimates. However, their need for large datasets to successfully separate the different phase contributions limits their performance if data is scarce and irregularly sampled. Limited SAR data coverage is true for many areas affected by geophysical deformation. This is either due to their low priority in mission programming, unfavorable ground coverage condition, or turbulent seasonal weather effects. In this paper, we present new adaptive atmospheric phase filtering algorithms that are specifically designed to reconstruct surface deformation signals from atmosphere-affected and irregularly sampled InSAR time series. The filters take advantage of auxiliary atmospheric delay information that is extracted from various sources, e.g. atmospheric weather models. They are embedded into a model-free Persistent Scatterer Interferometry (PSI) approach that was selected to accommodate non-linear deformation patterns that are often observed near volcanoes and earthquake zones. Two types of adaptive phase filters were developed that operate in the time dimension and separate atmosphere from deformation based on their different temporal correlation properties. Both filter types use the fact that atmospheric models can reliably predict the spatial statistics and signal power of atmospheric phase delay fields in order to automatically optimize the filter's shape parameters. In essence, both filter types will attempt to maximize the linear correlation between a-priori and the extracted atmospheric phase information. Topography-related phase components, orbit errors and the master atmospheric delays are first removed in a pre-processing step before the atmospheric filters are applied. The first adaptive filter type is using a filter kernel of Gaussian shape and is adaptively adjusting the width (defined in days) of this filter until the correlation of extracted and modeled atmospheric signal power is maximized. If atmospheric properties vary along the time series, this approach will lead to filter setting that are adapted to best reproduce atmospheric conditions at a certain observation epoch. Despite the superior performance of this first filter design, its Gaussian shape imposes non-physical relative weights onto acquisitions that ignore the known atmospheric noise in the data. Hence, in our second approach we are using atmospheric a-priori information to adaptively define the full shape of the atmospheric filter. For this process, we use a so-called normalized convolution (NC) approach that is often used in image reconstruction. Several NC designs will be presented in this paper and studied for relative performance. A cross-validation of all developed algorithms was done using both synthetic and real data. This validation showed designed filters are outperforming conventional filter methods that particularly useful for regions with limited data coverage or lack of a deformation field prior.

THE EVOLUTION OF SOLAR FLUX FROM 0.1 nm TO 160 {mu}m: QUANTITATIVE ESTIMATES FOR PLANETARY STUDIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Claire, Mark W.; Sheets, John; Meadows, Victoria S.

2012-09-20

Understanding changes in the solar flux over geologic time is vital for understanding the evolution of planetary atmospheres because it affects atmospheric escape and chemistry, as well as climate. We describe a numerical parameterization for wavelength-dependent changes to the non-attenuated solar flux appropriate for most times and places in the solar system. We combine data from the Sun and solar analogs to estimate enhanced UV and X-ray fluxes for the young Sun and use standard solar models to estimate changing visible and infrared fluxes. The parameterization, a series of multipliers relative to the modern top of the atmosphere flux atmore » Earth, is valid from 0.1 nm through the infrared, and from 0.6 Gyr through 6.7 Gyr, and is extended from the solar zero-age main sequence to 8.0 Gyr subject to additional uncertainties. The parameterization is applied to a representative modern day flux, providing quantitative estimates of the wavelength dependence of solar flux for paleodates relevant to the evolution of atmospheres in the solar system (or around other G-type stars). We validate the code by Monte Carlo analysis of uncertainties in stellar age and flux, and with comparisons to the solar proxies {kappa}{sup 1} Cet and EK Dra. The model is applied to the computation of photolysis rates on the Archean Earth.« less

Atmospheric thermal tides and planetary spin. I. The complex interplay between stratification and rotation

NASA Astrophysics Data System (ADS)

Auclair-Desrotour, P.; Mathis, S.; Laskar, J.

2018-02-01

Context. Thermal atmospheric tides can torque telluric planets away from spin-orbit synchronous rotation, as observed in the case of Venus. They thus participate in determining the possible climates and general circulations of the atmospheres of these planets. Aims: The thermal tidal torque exerted on an atmosphere depends on its internal structure and rotation and on the tidal frequency. Particularly, it strongly varies with the convective stability of the entropy stratification. This dependence has to be characterized to constrain and predict the rotational properties of observed telluric exoplanets. Moreover, it is necessary to validate the approximations used in global modelings such as the traditional approximation, which is used to obtain separable solutions for tidal waves. Methods: We wrote the equations governing the dynamics of thermal tides in a local vertically stratified section of a rotating planetary atmosphere by taking into account the effects of the complete Coriolis acceleration on tidal waves. This allowed us to analytically derive the tidal torque and the tidally dissipated energy, which we used to discuss the possible regimes of tidal dissipation and to examine the key role played by stratification. Results: In agreement with early studies, we find that the frequency dependence of the thermal atmospheric tidal torque in the vicinity of synchronization can be approximated by a Maxwell model. This behavior corresponds to weakly stably stratified or convective fluid layers, as observed previously. A strong stable stratification allows gravity waves to propagate, and makes the tidal torque negligible. The transition is continuous between these two regimes. The traditional approximation appears to be valid in thin atmospheres and in regimes where the rotation frequency is dominated by the forcing or the buoyancy frequencies. Conclusions: Depending on the stability of their atmospheres with respect to convection, observed exoplanets can be tidally driven toward synchronous or asynchronous final rotation rates. The domain of applicability of the traditional approximation is rigorously constrained by calculations.

NASA Soil Moisture Data Products and Their Incorporation in DREAM

NASA Technical Reports Server (NTRS)

Blonski, Slawomir; Holland, Donald; Henderson, Vaneshette

2005-01-01

NASA provides soil moisture data products that include observations from the Advanced Microwave Scanning Radiometer on the Earth Observing System Aqua satellite, field measurements from the Soil Moisture Experiment campaigns, and model predictions from the Land Information System and the Goddard Earth Observing System Data Assimilation System. Incorporation of the NASA soil moisture products in the Dust Regional Atmospheric Model is possible through use of the satellite observations of soil moisture to set initial conditions for the dust simulations. An additional comparison of satellite soil moisture observations with mesoscale atmospheric dynamics modeling is recommended. Such a comparison would validate the use of NASA soil moisture data in applications and support acceptance of satellite soil moisture data assimilation in weather and climate modeling.

Rain scavenging of solid rocket exhaust clouds

NASA Technical Reports Server (NTRS)

Dingle, A. N.

1978-01-01

An explicit model for cloud microphysics was developed for application to the problem of co-condensation/vaporization of HCl and H2O in the presence of Al2O3 particulate nuclei. Validity of the explicit model relative to the implicit model, which has been customarily applied to atmospheric cloud studies, was demonstrated by parallel computations of H2O condensation upon (NH4)2 SO4 nuclei. A mesoscale predictive model designed to account for the impact of wet processes on atmospheric dynamics is also under development. Input data specifying the equilibrium state of HC1 and H2O vapors in contact with aqueous HC1 solutions were found to be limited, particularly in respect to temperature range.

Collisional radiative model of an argon atmospheric capillary surface-wave discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yanguas-Gil, A.; Cotrino, J.; Gonzalez-Elipe, A.R.

2004-12-01

The characteristics of a microwave surface-wave sustained plasma operated at atmospheric pressure in an open-ended dielectric tube are investigated theoretically as a first step in the development of a self-consistent model for these discharges. The plasma column is sustained in flowing argon. A surface-wave discharge that fills the whole radial cross section of the discharge tube is considered. With experimental electron temperature profiles [Garcia et al., Spectrochim. Acta, Part B 55, 1733 (2000)] the numerical model is used to test the validity of the different approximations and to study the influence of the different kinetic processes and power loss mechanismsmore » on the discharge.« less

Site selection and directional models of deserts used for ERBE validation targets

NASA Technical Reports Server (NTRS)

Staylor, W. F.

1986-01-01

Broadband shortwave and longwave radiance measurements obtained from the Nimbus 7 Earth Radiation Budget scanner were used to develop reflectance and emittance models for the Sahara, Gibson, and Saudi Deserts. These deserts will serve as in-flight validation targets for the Earth Radiation Budget Experiment being flown on the Earth Radiation Budget Satellite and two National Oceanic and Atmospheric Administration polar satellites. The directional reflectance model derived for the deserts was a function of the sum and product of the cosines of the solar and viewing zenith angles, and thus reciprocity existed between these zenith angles. The emittance model was related by a power law of the cosine of the viewing zenith angle.

Simple three-pool model accurately describes patterns of long-term litter decomposition in diverse climates

Treesearch

E. Carol Adair; William J. Parton; Steven J. Del Grosso; Shendee L. Silver; Mark E. Harmon; Sonia A. Hall; Ingrid C. Burke; Stephen C. Hart

2008-01-01

As atmospheric CO2 increases, ecosystem carbon sequestration will largely depend on how global changes in climate will alter the balance between net primary production and decomposition. The response of primary production to climatic change has been examined using well-validated mechanistic models, but the same is not true for decomposition, a...

Quantification of the water vapor greenhouse effect: setup and first results of the Zugspitze radiative closure experiment

NASA Astrophysics Data System (ADS)

Reichert, Andreas; Sussmann, Ralf; Rettinger, Markus

2014-05-01

Uncertainties in the knowledge of atmospheric radiative processes are among the main limiting factors for the accuracy of current climate models. Being the primary greenhouse gas in the Earth's atmosphere, water vapor is of crucial importance in atmospheric radiative transfer. However, water vapor absorption processes, especially the contribution attributed to the water vapor continuum, are currently not sufficiently well quantified. The aim of this study is therefore to obtain a more exact characterization of the water vapor radiative processes throughout the IR by means of a so-called radiative closure study at the Zugspitze/Schneefernerhaus observatory and thereby validate the radiative transfer codes used in current climate models. For that purpose, spectral radiance is measured at the Zugspitze summit observatory using an AERI-ER thermal emission radiometer (covering the far- and mid-infrared) and a solar absorption FTIR spectrometer (covering the near-infrared), respectively. These measurements are then compared to synthetic radiance spectra computed by means of the Line-By-Line Radiative Transfer Model (LBLRTM, Clough et al., 2005), a high resolution model widely used in the atmospheric science community. This line-by-line code provides the foundation of RRTM, a rapid radiation code (Mlawer et al., 1997) used in various weather forecast models or general circulation models like ECHAM. To be able to quantify errors in the description of water vapor radiative processes from spectral residuals, i.e. difference spectra between measured and calculated radiance, the atmospheric state used as an input to LBLRTM has to be constrained precisely. This input comprises water vapor columns, water vapor profiles, and temperature profiles measured by an LHATPRO microwave radiometer along with total column information on further trace gases (e.g. CO2 and O3) measured by the solar FTIR. We will present the setup of the Zugspitze radiative closure experiment. Due to its high-altitude location and the available permanent instrumentation, the Zugspitze observatory meets the necessary requirements to determine highly accurate water vapor continuum absorption parameters in the far- and mid-infrared spectral range from a more extensive set of closure measurements compared to previous campaign-based studies. Furthermore, we will present a novel radiometric calibration strategy for the solar FTIR spectral radiance measurements based on a combination of the Langley method and measurements of a high-temperature blackbody source that allows for the determination of continuum absorption parameters in the near-infrared spectral region, where previously no precise measurements under atmospheric conditions were available. This improved quantification of water vapor continuum absorption parameters allows us to further validate the current standard continuum model MT_CKD (Mlawer et al., 2012). Acknowledgements: Funding by KIT/IMK-IFU, the State Government of Bavaria as well as by the Deutsche Bundesstiftung Umwelt (DBU) is gratefully acknowledged. References: Clough, S. A., Shephard, M. W., Mlawer, E. J., Delamere, J. S., Iacono, M. J., Cady-Pereira, K., Boukabara, S., and Brown, P. D: Atmospheric radiative transfer modeling: a summary of the AER codes, Short Communication, J. Quant. Spectrosc. Radiat. Transfer, 91, 233-244, 2005. Mlawer, E. J., Taubman, J., Brown, P.D., Iacono, M.J, and Clough, S.A.: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res., 102, 16,663-16,682, 1997. Mlawer, E. J., Payne V. H., Moncet, J., Delamere, J. S., Alvarado, M. J. and Tobin, D.C.: Development and recent evaluation of the MT_CKD model of continuum absorption, Phil. Trans. R. Soc. A, 370, 2520-2556, 2012.

The role of global cloud climatologies in validating numerical models

NASA Technical Reports Server (NTRS)

HARSHVARDHAN

1991-01-01

Reliable estimates of the components of the surface radiation budget are important in studies of ocean-atmosphere interaction, land-atmosphere interaction, ocean circulation and in the validation of radiation schemes used in climate models. The methods currently under consideration must necessarily make certain assumptions regarding both the presence of clouds and their vertical extent. Because of the uncertainties in assumed cloudiness, all these methods involve perhaps unacceptable uncertainties. Here, a theoretical framework that avoids the explicit computation of cloud fraction and the location of cloud base in estimating the surface longwave radiation is presented. Estimates of the global surface downward fluxes and the oceanic surface net upward fluxes were made for four months (April, July, October and January) in 1985 to 1986. These estimates are based on a relationship between cloud radiative forcing at the top of the atmosphere and the surface obtained from a general circulation model. The radiation code is the version used in the UCLA/GLA general circulation model (GCM). The longwave cloud radiative forcing at the top of the atmosphere as obtained from Earth Radiation Budget Experiment (ERBE) measurements is used to compute the forcing at the surface by means of the GCM-derived relationship. This, along with clear-sky fluxes from the computations, yield maps of the downward longwave fluxes and net upward longwave fluxes at the surface. The calculated results are discussed and analyzed. The results are consistent with current meteorological knowledge and explainable on the basis of previous theoretical and observational works; therefore, it can be concluded that this method is applicable as one of the ways to obtain the surface longwave radiation fields from currently available satellite data.

A Physical Model to Determine Snowfall over Land by Microwave Radiometry

NASA Technical Reports Server (NTRS)

Skofronick-Jackson, G.; Kim, M.-J.; Weinman, J. A.; Chang, D.-E.

2003-01-01

Because microwave brightness temperatures emitted by snow covered surfaces are highly variable, snowfall above such surfaces is difficult to observe using window channels that occur at low frequencies (v less than 100 GHz). Furthermore, at frequencies v less than or equal to 37 GHz, sensitivity to liquid hydrometeors is dominant. These problems are mitigated at high frequencies (v greater than 100 GHz) where water vapor screens the surface emission and sensitivity to frozen hydrometeors is significant. However the scattering effect of snowfall in the atmosphere at those higher frequencies is also impacted by water vapor in the upper atmosphere. This work describes the methodology and results of physically-based retrievals of snow falling over land surfaces. The theory of scattering by randomly oriented dry snow particles at high microwave frequencies appears to be better described by regarding snow as a concatenation of equivalent ice spheres rather than as a sphere with the effective dielectric constant of an air-ice mixture. An equivalent sphere snow scattering model was validated against high frequency attenuation measurements. Satellite-based high frequency observations from an Advanced Microwave Sounding Unit (AMSU-B) instrument during the March 5-6, 2001 New England blizzard were used to retrieve snowfall over land. Vertical distributions of snow, temperature and relative humidity profiles were derived from the Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) fifth-generation Mesoscale Model (MM5). Those data were applied and modified in a radiative transfer model that derived brightness temperatures consistent with the AMSU-B observations. The retrieved snowfall distribution was validated with radar reflectivity measurements obtained from the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) ground-based radar network.

Validation of the DIFFAL, HPAC and HotSpot Dispersion Models Using the Full-Scale Radiological Dispersal Device (FSRDD) Field Trials Witness Plate Deposition Dataset.

PubMed

Purves, Murray; Parkes, David

2016-05-01

Three atmospheric dispersion models--DIFFAL, HPAC, and HotSpot--of differing complexities have been validated against the witness plate deposition dataset taken during the Full-Scale Radiological Dispersal Device (FSRDD) Field Trials. The small-scale nature of these trials in comparison to many other historical radiological dispersion trials provides a unique opportunity to evaluate the near-field performance of the models considered. This paper performs validation of these models using two graphical methods of comparison: deposition contour plots and hotline profile graphs. All of the models tested are assessed to perform well, especially considering that previous model developments and validations have been focused on larger-scale scenarios. Of the models, HPAC generally produced the most accurate results, especially at locations within ∼100 m of GZ. Features present within the observed data, such as hot spots, were not well modeled by any of the codes considered. Additionally, it was found that an increase in the complexity of the meteorological data input to the models did not necessarily lead to an improvement in model accuracy; this is potentially due to the small-scale nature of the trials.

Application of a wind-wave-current coupled model in the Catalan coast (NW Mediterranean sea), for wind energy purposes

NASA Astrophysics Data System (ADS)

María Palomares, Ana; Navarro, Jorge; Grifoll, Manel; Pallares, Elena; Espino, Manuel

2016-04-01

This work shows the main results of the HAREAMAR project (including HAREMAR, ENE2012-38772-C02-01 and DARDO, ENE2012-38772-C02-02 projects), concerning the local Wind, Wave and Current simulation at St. Jordi Bay (NW Mediterranean Sea). Offshore Wind Energy has become one of the main topics within the research in Wind Energy research. Although there are quite a few models with a high level of reliability for wind simulation and prediction in onshore places, the wind prediction needs further investigations for adaptation to the Offshore emplacements, taking into account the interaction atmosphere-ocean. The main problem in these ocean areas is the lack of wind data, which neither allows for characterizing the energy potential and wind behaviour in a particular place, nor validating the forecasting models. The main objective of this work is to reduce the local prediction errors, in order to make the meteo-oceanographic hindcast and forecast more reliable. The COAWST model (Coupled-Ocean-Atmosphere-Wave Sediment Transport Model; Warner et al., 2010) system has been implemented in the region considering a set of downscaling nested meshes to obtain high-resolution outputs in the region. The adaptation to this particular area, combining the different wind, wave and ocean model domains has been far from simple, because the grid domains for the three models differ significantly. This work shows the main results of the COAWST model implementation to this particular area, including both monthly and other set of tests in different atmospheric situations, especially chosen for their particular interest. The time period considered for the validation is the whole year 2012. A comparative study between the WRF, SWAN and ROMS model outputs (without coupling), the COWAST model outputs, and a buoy measurements moored in the region was performed for this year. References Warner, J.C., Armstrong, B., He, R., and Zambon, J.B., 2010, Development of a Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system: Ocean Modeling, 35 (3), 230-244.

Development and Validation of a Polarimetric-MCScene 3D Atmospheric Radiation Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berk, Alexander; Hawes, Frederick; Fox, Marsha

2016-03-15

Polarimetric measurements can substantially enhance the ability of both spectrally resolved and single band imagery to detect the proliferation of weapons of mass destruction, providing data for locating and identifying facilities, materials, and processes of undeclared and proliferant nuclear weapons programs worldwide. Unfortunately, models do not exist that efficiently and accurately predict spectral polarized signatures for the materials of interest embedded in complex 3D environments. Having such a model would enable one to test hypotheses and optimize both the enhancement of scene contrast and the signal processing for spectral signature extraction. The Phase I set the groundwork for development ofmore » fully validated polarimetric spectral signature and scene simulation models. This has been accomplished 1. by (a) identifying and downloading state-of-the-art surface and atmospheric polarimetric data sources, (b) implementing tools for generating custom polarimetric data, and (c) identifying and requesting US Government funded field measurement data for use in validation; 2. by formulating an approach for upgrading the radiometric spectral signature model MODTRAN to generate polarimetric intensities through (a) ingestion of the polarimetric data, (b) polarimetric vectorization of existing MODTRAN modules, and (c) integration of a newly developed algorithm for computing polarimetric multiple scattering contributions; 3. by generating an initial polarimetric model that demonstrates calculation of polarimetric solar and lunar single scatter intensities arising from the interaction of incoming irradiances with molecules and aerosols; 4. by developing a design and implementation plan to (a) automate polarimetric scene construction and (b) efficiently sample polarimetric scattering and reflection events, for use in a to be developed polarimetric version of the existing first-principles synthetic scene simulation model, MCScene; and 5. by planning a validation field measurement program in collaboration with the Remote Sensing and Exploitation group at Sandia National Laboratories (SNL) in which data from their ongoing polarimetric field and laboratory measurement program will be shared and, to the extent allowed, tailored for model validation in exchange for model predictions under conditions and for geometries outside of their measurement domain.« less

Scattering in infrared radiative transfer: A comparison between the spectrally averaging model JURASSIC and the line-by-line model KOPRA

NASA Astrophysics Data System (ADS)

Griessbach, Sabine; Hoffmann, Lars; Höpfner, Michael; Riese, Martin; Spang, Reinhold

2013-09-01

The viability of a spectrally averaging model to perform radiative transfer calculations in the infrared including scattering by atmospheric particles is examined for the application of infrared limb remote sensing measurements. Here we focus on the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European Space Agency's Envisat. Various spectra for clear air and cloudy conditions were simulated with a spectrally averaging radiative transfer model and a line-by-line radiative transfer model for three atmospheric window regions (825-830, 946-951, 1224-1228 cm-1) and compared to each other. The results are rated in terms of the MIPAS noise equivalent spectral radiance (NESR). The clear air simulations generally agree within one NESR. The cloud simulations neglecting the scattering source term agree within two NESR. The differences between the cloud simulations including the scattering source term are generally below three and always below four NESR. We conclude that the spectrally averaging approach is well suited for fast and accurate infrared radiative transfer simulations including scattering by clouds. We found that the main source for the differences between the cloud simulations of both models is the cloud edge sampling. Furthermore we reasoned that this model comparison for clouds is also valid for atmospheric aerosol in general.

Imaging simulation of active EO-camera

NASA Astrophysics Data System (ADS)

Pérez, José; Repasi, Endre

2018-04-01

A modeling scheme for active imaging through atmospheric turbulence is presented. The model consists of two parts: In the first part, the illumination laser beam is propagated to a target that is described by its reflectance properties, using the well-known split-step Fourier method for wave propagation. In the second part, the reflected intensity distribution imaged on a camera is computed using an empirical model developed for passive imaging through atmospheric turbulence. The split-step Fourier method requires carefully chosen simulation parameters. These simulation requirements together with the need to produce dynamic scenes with a large number of frames led us to implement the model on GPU. Validation of this implementation is shown for two different metrics. This model is well suited for Gated-Viewing applications. Examples of imaging simulation results are presented here.

Towards the Adriatic meteotsunami early warning system: modelling strategy and validation

NASA Astrophysics Data System (ADS)

Denamiel, Clea; Šepić, Jadranka; Vilibić, Ivica

2017-04-01

Destructive meteotsunamis are known to occur along the eastern Adriatic coastal areas and islands (Vilibić and Šepić, 2009). The temporal lag between the offshore generation of meteotsunamis due to specific atmospheric conditions and the arrival of a dangerous nearshore propagating wave at known locations is of the order of tens of minutes to a couple of hours. In order to reduce the coastal risk for the coastal communities, an early warning system must rely on the ability to detect these extreme storms offshore with in-situ measurements and to predict the hydrodynamic response nearshore via numerical models within this short time lag. However, the numerical modelling of meteotsunamis requires both temporal and spatial high-resolution atmospheric and ocean models which are highly demanding concerning time and computer resources. Furthermore, both a multi-model approach and an ensemble modelling strategy should be used to better forecast the distribution of the nearshore impact of meteotsunamis. The modelling strategy used in this study thus rely on the development of an operational atmosphere-ocean model of the Adriatic Sea at 1km spatial resolution based on the state-of-the-art fully coupled COAWST model (Warner et al., 2010). The model allows for generation of meteotsunamis offshore, while various high-resolution (up to 5m) nearshore hydrodynamic models (such as ADCIRC - Luettich and Westerink, 1991; SELFE - Zhang et al., 2008 and GeoClaw - LeVeque, 2012) are setup to properly reproduce meteotsunami dynamics of the entire Croatian coastal areas, which are characterized by a great number of islands, channels and bays. The implementation and validation of each component of this modelling system is first undertaken for the well documented meteotsunami event (Šepić et al., 2016), which was recorded along the Croatian Adriatic coast on the 25th and the 26th of June 2014. The validation of the modelling strategy as well as the model results is presented and discussed in this study. LeVeque, R.J., 2002. Finite Volume Methods for Hyperbolic Problems. Cambridge University Press. Luettich, R.A., and Westerink, J.J., 1991. A solution for the vertical variation of stress, rather than velocity, in a three-dimensional circulation model. International Journal for Numerical Methods in Fluids, 12, 911-928. Šepić, J., Međogorac, I., Janeković, I., Dunić, N., and Vilibić, I., 2016. Multi-Meteotsunami Event in the Adriatic Sea Generated by Atmospheric Disturbances of 25-26 June 2014. Pure and Applied Geophysics, DOI 10.1007/s00024-016-1249-4. Vilibić, I., Šepić, J., 2009. Destructive meteotsunamis along the eastern Adriatic coast: overview. Physics and Chemistry of the Earth, 34, 904-917. Warner, J.C., Armstrong, B., He, R.Y., and Zambon, J.B., 2010. Development of a coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling System. Ocean Modelling, 35(3), 230-244. Zhang, Y.J., and Baptista, A.M., 2008. SELFE: A semi-implicit Eulerian-Langrangian finite-element model for cross-scale ocean circulation. Ocean Modelling, 21, 71-96.

Improving UK Air Quality Modelling Through Exploitation of Satellite Observations

NASA Astrophysics Data System (ADS)

Pope, Richard; Chipperfield, Martyn; Savage, Nick

2014-05-01

In this work the applicability of satellite observations to evaluate the operational UK Met Office Air Quality in the Unified Model (AQUM) have been investigated. The main focus involved the AQUM validation against satellite observations, investigation of satellite retrieval error types and of synoptic meteorological-atmospheric chemistry relationships simulated/seen by the AQUM/satellite. The AQUM is a short range forecast model of atmospheric chemistry and aerosols up to 5 days. It has been designed to predict potentially hazardous air pollution events, e.g. high concentrations of surface ozone. The AQUM has only been validated against UK atmospheric chemistry recording surface stations. Therefore, satellite observations of atmospheric chemistry have been used to further validate the model, taking advantage of better satellite spatial coverage. Observations of summer and winter 2006 tropospheric column NO2 from both OMI and SCIAMACHY show that the AQUM generally compares well with the observations. However, in northern England positive biases (AQUM - satellite) suggest that the AQUM overestimates column NO2; we present results of sensitivity experiments on UK emissions datasets suspected to be the cause. In winter, the AQUM over predicts background column NO2 when compared to both satellite instruments. We hypothesise that the cause is the AQUM winter night-time chemistry, where the NO2 sinks are not substantially defined. Satellite data are prone to errors/uncertainty such as random, systematic and smoothing errors. We have investigated these error types and developed an algorithm to calculate and reduce the random error component of DOAS NO2 retrievals, giving more robust seasonal satellite composites. The Lamb Weather Types (LWT), an objective method of classifying the daily synoptic weather over the UK, were used to create composite satellite maps of column NO2 under different synoptic conditions. Under cyclonic conditions, satellite observed UK column NO2 is reduced as the indicative south-westerly flow transports it away from the UK over the North Sea. However, under anticyclonic conditions, the satellite shows that the stable conditions enhance the build-up of column NO2 over source regions. The influence of wind direction on column NO2 can also be seen from space with transport leeward of the source regions.

Are atmospheric surface layer flows ergodic?

NASA Astrophysics Data System (ADS)

Higgins, Chad W.; Katul, Gabriel G.; Froidevaux, Martin; Simeonov, Valentin; Parlange, Marc B.

2013-06-01

The transposition of atmospheric turbulence statistics from the time domain, as conventionally sampled in field experiments, is explained by the so-called ergodic hypothesis. In micrometeorology, this hypothesis assumes that the time average of a measured flow variable represents an ensemble of independent realizations from similar meteorological states and boundary conditions. That is, the averaging duration must be sufficiently long to include a large number of independent realizations of the sampled flow variable so as to represent the ensemble. While the validity of the ergodic hypothesis for turbulence has been confirmed in laboratory experiments, and numerical simulations for idealized conditions, evidence for its validity in the atmospheric surface layer (ASL), especially for nonideal conditions, continues to defy experimental efforts. There is some urgency to make progress on this problem given the proliferation of tall tower scalar concentration networks aimed at constraining climate models yet are impacted by nonideal conditions at the land surface. Recent advancements in water vapor concentration lidar measurements that simultaneously sample spatial and temporal series in the ASL are used to investigate the validity of the ergodic hypothesis for the first time. It is shown that ergodicity is valid in a strict sense above uniform surfaces away from abrupt surface transitions. Surprisingly, ergodicity may be used to infer the ensemble concentration statistics of a composite grass-lake system using only water vapor concentration measurements collected above the sharp transition delineating the lake from the grass surface.

Volcanic Plume Heights on Mars: Limits of Validity for Convective Models

NASA Technical Reports Server (NTRS)

Glaze, Lori S.; Baloga, Stephen M.

2002-01-01

Previous studies have overestimated volcanic plume heights on Mars. In this work, we demonstrate that volcanic plume rise models, as currently formulated, have only limited validity in any environment. These limits are easily violated in the current Mars environment and may also be violated for terrestrial and early Mars conditions. We indicate some of the shortcomings of the model with emphasis on the limited applicability to current Mars conditions. Specifically, basic model assumptions are violated when (1) vertical velocities exceed the speed of sound, (2) radial expansion rates exceed the speed of sound, (3) radial expansion rates approach or exceed the vertical velocity, or (4) plume radius grossly exceeds plume height. All of these criteria are violated for the typical Mars example given here. Solutions imply that the convective rise, model is only valid to a height of approximately 10 kilometers. The reason for the model breakdown is hat the current Mars atmosphere is not of sufficient density to satisfy the conservation equations. It is likely that diffusion and other effects governed by higher-order differential equations are important within the first few kilometers of rise. When the same criteria are applied to eruptions into a higher-density early Mars atmosphere, we find that eruption rates higher than 1.4 x 10(exp 9) kilograms per second also violate model assumptions. This implies a maximum extent of approximately 65 kilometers for convective plumes on early Mars. The estimated plume heights for both current and early Mars are significantly lower than those previously predicted in the literature. Therefore, global-scale distribution of ash seems implausible.

Operational atmospheric correction of AVHRR visible and infrared data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vermote, E.; El Saleous, N.; Roger, J.C.

1995-12-31

The satellite level radiance is affected by the presence of the atmosphere between the sensor and the target. The ozone and water vapor absorption bands affect the signal recorded by the AVHRR visible and near infrared channels respectively. The Rayleigh scattering mainly affects the visible channel and is more pronounced when dealing with small sun elevations and large view angles. The aerosol scattering affects both channels and is certainly the most challenging term for atmospheric correction because of the spatial and temporal variability of both the type and amount of particles in the atmosphere. This paper presents the equation ofmore » the satellite signal, the scheme to retrieve atmospheric properties and corrections applied to AVHRR observations. The operational process uses TOMS data and a digital elevation model to correct for ozone absorption and rayleigh scattering. The water vapor content is evaluated using the split-window technique that is validated over ocean using 1988 SSM/I data. The aerosol amount retrieval over Ocean is achieved in channels 1 and 2 and compared to sun photometer observations to check consistency of the radiative transfer model and the sensor calibration. Over land, the method developed uses reflectance at 3.75 microns to deduce target reflectance in channel 1 and retrieve aerosol optical thickness that can be extrapolated in channel 2. The method to invert the reflectance at 3.75 microns is based on MODTRAN simulations and is validated by comparison to measurements performed during FIFE 87. Finally, aerosol optical thickness retrieved over Brazil and Eastern US is compared to sun photometer measurements.« less

Advection of Potential Temperature in the Atmosphere of Irradiated Exoplanets: A Robust Mechanism to Explain Radius Inflation

NASA Technical Reports Server (NTRS)

Tremblin, P.; Chabrier, G.; Mayne, N. J.; Amundsen, D. S.; Baraffe, I.; Debras, F.; Drummond, B.; Manners, J.; Fromang, S.

2017-01-01

The anomalously large radii of strongly irradiated exoplanets have remained a major puzzle in astronomy. Based on a two-dimensional steady-state atmospheric circulation model, the validity of which is assessed by comparison to three-dimensional calculations, we reveal a new mechanism, namely the advection of the potential temperature due to mass and longitudinal momentum conservation, a process occurring in the Earth's atmosphere or oceans. In the deep atmosphere, the vanishing heating flux forces the atmospheric structure to converge to a hotter adiabat than the one obtained with 1D calculations, implying a larger radius for the planet. Not only do the calculations reproduce the observed radius of HD 209458b, but also reproduce the observed correlation between radius inflation and irradiation for transiting planets. Vertical advection of potential temperature induced by non-uniform atmospheric heating thus provides a robust mechanism to explain the inflated radii of irradiated hot Jupiters.

Accurate Ray-tracing of Realistic Neutron Star Atmospheres for Constraining Their Parameters

NASA Astrophysics Data System (ADS)

Vincent, Frederic H.; Bejger, Michał; Różańska, Agata; Straub, Odele; Paumard, Thibaut; Fortin, Morgane; Madej, Jerzy; Majczyna, Agnieszka; Gourgoulhon, Eric; Haensel, Paweł; Zdunik, Leszek; Beldycki, Bartosz

2018-03-01

Thermal-dominated X-ray spectra of neutron stars in quiescent, transient X-ray binaries and neutron stars that undergo thermonuclear bursts are sensitive to mass and radius. The mass–radius relation of neutron stars depends on the equation of state (EoS) that governs their interior. Constraining this relation accurately is therefore of fundamental importance to understand the nature of dense matter. In this context, we introduce a pipeline to calculate realistic model spectra of rotating neutron stars with hydrogen and helium atmospheres. An arbitrarily fast-rotating neutron star with a given EoS generates the spacetime in which the atmosphere emits radiation. We use the LORENE/NROTSTAR code to compute the spacetime numerically and the ATM24 code to solve the radiative transfer equations self-consistently. Emerging specific intensity spectra are then ray-traced through the neutron star’s spacetime from the atmosphere to a distant observer with the GYOTO code. Here, we present and test our fully relativistic numerical pipeline. To discuss and illustrate the importance of realistic atmosphere models, we compare our model spectra to simpler models like the commonly used isotropic color-corrected blackbody emission. We highlight the importance of considering realistic model-atmosphere spectra together with relativistic ray-tracing to obtain accurate predictions. We also insist upon the crucial impact of the star’s rotation on the observables. Finally, we close a controversy that has been ongoing in the literature in the recent years, regarding the validity of the ATM24 code.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanz Rodrigo, Javier; Chávez Arroyo, Roberto Aurelio; Moriarty, Patrick

The increasing size of wind turbines, with rotors already spanning more than 150 m diameter and hub heights above 100 m, requires proper modeling of the atmospheric boundary layer (ABL) from the surface to the free atmosphere. Furthermore, large wind farm arrays create their own boundary layer structure with unique physics. This poses significant challenges to traditional wind engineering models that rely on surface-layer theories and engineering wind farm models to simulate the flow in and around wind farms. However, adopting an ABL approach offers the opportunity to better integrate wind farm design tools and meteorological models. The challenge ismore » how to build the bridge between atmospheric and wind engineering model communities and how to establish a comprehensive evaluation process that identifies relevant physical phenomena for wind energy applications with modeling and experimental requirements. A framework for model verification, validation, and uncertainty quantification is established to guide this process by a systematic evaluation of the modeling system at increasing levels of complexity. In terms of atmospheric physics, 'building the bridge' means developing models for the so-called 'terra incognita,' a term used to designate the turbulent scales that transition from mesoscale to microscale. This range of scales within atmospheric research deals with the transition from parameterized to resolved turbulence and the improvement of surface boundary-layer parameterizations. The coupling of meteorological and wind engineering flow models and the definition of a formal model evaluation methodology, is a strong area of research for the next generation of wind conditions assessment and wind farm and wind turbine design tools. Some fundamental challenges are identified in order to guide future research in this area.« less

Numerical Modeling Studies of Wake Vortex Transport and Evolution Within the Planetary Boundary Layer

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Arya, S. Pal; Kaplan, Michael L.; Han, Jongil

2000-01-01

The fundamental objective of this research is study behavior of aircraft wake vortices within atmospheric boundary layer (ABL) in support of developing the system, Aircraft VOrtex Spacing System (AVOSS), under NASA's Terminal Area Productivity (TAR) program that will control aircraft spacing within the narrow approach corridors of airports. The purpose of the AVOSS system is to increase airport capacity by providing a safe reduction in separation of aircraft compared to the now-existing flight rules. In our first funding period (7 January 19994 - 6 April 1997), we have accomplished extensive model development and validation of ABL simulations. Using the validated model, in our second funding period (7 April 1997 - 6 April 2000) we have investigated the effects of ambient atmospheric turbulence on vortex decay and descent, Crow instability, and wake vortex interaction with the ground. Recognizing the crucial influence of ABL turbulence on wake vortex behavior, we have also developed a software generating vertical profiles of turbulent kinetic energy (TKE) or energy dissipation rate (EDR), which are, in turn, used as input data in the AVOSS prediction algorithms.

Dynamics and Chemistry in Jovian Atmospheres: 2D Hydrodynamical Simulations

NASA Astrophysics Data System (ADS)

Bordwell, B. R.; Brown, B. P.; Oishi, J.

2016-12-01

A key component of our understanding of the formation and evolution of planetary systems is chemical composition. Problematically, however, in the atmospheres of cooler gas giants, dynamics on the same timescale as chemical reactions pull molecular abundances out of thermochemical equilibrium. These disequilibrium abundances are treated using what is known as the "quench" approximation, based upon the mixing length theory of convection. The validity of this approximation is questionable, though, as the atmospheres of gas giants encompass two distinct dynamic regimes: convective and radiative. To resolve this issue, we conduct 2D hydrodynamical simulations using the state-of-the-art pseudospectral simulation framework Dedalus. In these simulations, we solve the fully compressible equations of fluid motion in a local slab geometry that mimics the structure of a planetary atmosphere (convective zone underlying a radiative zone). Through the inclusion of passive tracers, we explore the transport properties of both regimes, and assess the validity of the classical eddy diffusion parameterization. With the addition of active tracers, we examine the interactions between dynamical and chemical processes, and generate prescriptions for the observational community. By providing insight into mixing and feedback mechanisms in Jovian atmospheres, this research lays a solid foundation for future global simulations and the construction of physically-sound models for current and future observations.

The investigation of O and N2 densities from the OSO-7 extreme UV data

NASA Technical Reports Server (NTRS)

1975-01-01

The results of solar radiation observations in the extreme ultra-violet spectrum from 200 A to 600 A made by the OSO-7 Satellite were studied. The results of the influence of attenuation by the atmosphere in the 250 to 500 km altitude range are presented. Using published molecular absorption cross-sections at 304 A and 256 A, the Jaccia atmospheric model is validated, and shows that a mean exospheric of 1050 K is appropriate for the sunset data.

Cloud cover determination in polar regions from satellite imagery

NASA Technical Reports Server (NTRS)

Barry, R. G.; Key, J. R.; Maslanik, J. A.

1988-01-01

The principal objectives of this project are: to develop suitable validation data sets to evaluate the effectiveness of the ISCCP operational algorithm for cloud retrieval in polar regions and to validate model simulations of polar cloud cover; to identify limitations of current procedures for varying atmospheric surface conditions, and to explore potential means to remedy them using textural classifiers: and to compare synoptic cloud data from a control run experiment of the Goddard Institute for Space Studies (GISS) climate model 2 with typical observed synoptic cloud patterns. Current investigations underway are listed and the progress made to date is summarized.

Treatment of uncertainties in atmospheric chemical systems: A combined modeling and experimental approach

NASA Astrophysics Data System (ADS)

Pun, Betty Kong-Ling

1998-12-01

Uncertainty is endemic in modeling. This thesis is a two- phase program to understand the uncertainties in urban air pollution model predictions and in field data used to validate them. Part I demonstrates how to improve atmospheric models by analyzing the uncertainties in these models and using the results to guide new experimentation endeavors. Part II presents an experiment designed to characterize atmospheric fluctuations, which have significant implications towards the model validation process. A systematic study was undertaken to investigate the effects of uncertainties in the SAPRC mechanism for gas- phase chemistry in polluted atmospheres. The uncertainties of more than 500 parameters were compiled, including reaction rate constants, product coefficients, organic composition, and initial conditions. Uncertainty propagation using the Deterministic Equivalent Modeling Method (DEMM) revealed that the uncertainties in ozone predictions can be up to 45% based on these parametric uncertainties. The key parameters found to dominate the uncertainties of the predictions include photolysis rates of NO2, O3, and formaldehyde; the rate constant for nitric acid formation; and initial amounts of NOx and VOC. Similar uncertainty analysis procedures applied to two other mechanisms used in regional air quality models led to the conclusion that in the presence of parametric uncertainties, the mechanisms cannot be discriminated. Research efforts should focus on reducing parametric uncertainties in photolysis rates, reaction rate constants, and source terms. A new tunable diode laser (TDL) infrared spectrometer was designed and constructed to measure multiple pollutants simultaneously in the same ambient air parcels. The sensitivities of the one hertz measurements were 2 ppb for ozone, 1 ppb for NO, and 0.5 ppb for NO2. Meteorological data were also collected for wind, temperature, and UV intensity. The field data showed clear correlations between ozone, NO, and NO2 in the one-second time scale. Fluctuations in pollutant concentrations were found to be extremely dependent on meteorological conditions. Deposition fluxes calculated using the Eddy Correlation technique were found to be small on concrete surfaces. These high time-resolution measurements were used to develop an understanding of the variability in atmospheric measurements, which would be useful in determining the acceptable discrepancy of model and observations. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Simulating the Regional Impact of Dust on the Middle East Climate and the Red Sea

NASA Astrophysics Data System (ADS)

Osipov, Sergey; Stenchikov, Georgiy

2018-02-01

The Red Sea is located between North Africa and the Arabian Peninsula, the largest sources of dust in the world. Satellite retrievals show very high aerosol optical depth in the region, which increases during the summer season, especially over the southern Red Sea. Previously estimated and validated radiative effect from dust is expected to have a profound thermal and dynamic impact on the Red Sea, but that impact has not yet been studied or evaluated. Due to the strong dust radiative effect at the sea surface, uncoupled ocean modeling approaches with prescribed atmospheric boundary conditions result in an unrealistic ocean response. Therefore, to study the impact of dust on the regional climate of the Middle East and the Red Sea, we employed the Regional Ocean Modeling System fully coupled with the Weather Research and Forecasting model. We modified the atmospheric model to account for the radiative effect of dust. The simulations show that, in the equilibrium response, dust cools the Red Sea, reduces the surface wind speed, and weakens both the exchange at the Bab-el-Mandeb strait and the overturning circulation. The salinity distribution, freshwater, and heat budgets are significantly altered. A validation of the simulations against satellite products indicates that accounting for radiative effect from dust almost completely removes the bias and reduces errors in the top of the atmosphere fluxes and sea surface temperature. Our results suggest that dust plays an important role in the energy balance, thermal, and circulation regimes in the Red Sea.

Utilizing Mars Global Reference Atmospheric Model (Mars-GRAM 2005) to Evaluate Entry Probe Mission Sites

NASA Technical Reports Server (NTRS)

Justh, Hilary L.; Justus, C. G.

2008-01-01

Engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM s perturbation modeling capability is commonly used, in a Monte-Carlo mode, to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL)1. Traditional Mars-GRAM options for representing the mean atmosphere along entry corridors include: a) TES Mapping Years 1 and 2, with Mars-GRAM data coming from MGCM model results driven by observed TES dust optical depth; and b) TES Mapping Year 0, with user-controlled dust optical depth and Mars-GRAM data interpolated from MGCM model results driven by selected values of globally-uniform dust optical depth. From the surface to 80 km altitude, Mars-GRAM is based on NASA Ames Mars General Circulation Model (MGCM). Mars-GRAM and MGCM use surface topography from Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA), with altitudes referenced to the MOLA areoid, or constant potential surface. Mars-GRAM 2005 has been validated2 against Radio Science data, and both nadir and limb data from the Thermal Emission Spectrometer (TES)

Augmenting the SCaN Link Budget Tool with Validated Atmospheric Propagation

NASA Technical Reports Server (NTRS)

Steinkerchner, Leo; Welch, Bryan

2017-01-01

In any Earth-Space or Space-Earth communications link, atmospheric effects cause significant signal attenuation. In order to develop a communications system that is cost effective while meeting appropriate performance requirements, it is important to accurately predict these effects for the given link parameters. This project aimed to develop a Matlab(TradeMark) (The MathWorks, Inc.) program that could augment the existing Space Communications and Navigation (SCaN) Link Budget Tool with accurate predictions of atmospheric attenuation of both optical and radio-frequency signals according to the SCaN Optical Link Assessment Model Version 5 and the International Telecommunications Union, Radiocommunications Sector (ITU-R) atmospheric propagation loss model, respectively. When compared to data collected from the Advance Communications Technology Satellite (ACTS), the radio-frequency model predicted attenuation to within 1.3 dB of loss for 95 of measurements. Ultimately, this tool will be integrated into the SCaN Center for Engineering, Networks, Integration, and Communications (SCENIC) user interface in order to support analysis of existing SCaN systems and planning capabilities for future NASA missions.

Winds, waves and shorelines from ancient martian seas

NASA Astrophysics Data System (ADS)

Banfield, Don; Donelan, Mark; Cavaleri, Luigi

2015-04-01

We consider under what environmental conditions water waves (and thus eventually shorelines) should be expected to be produced on hypothetical ancient martian seas and lakes. For winds and atmospheric pressures that are too small, no waves should be expected, and thus no shorelines. If the winds and atmospheric pressure are above some threshold, then waves can be formed, and shorelines are possible. We establish these criteria separating conditions under which waves will or will not form on an ancient martian open body of water. We consider not only atmospheric pressure and wind, but also temperature and salinity, but find these latter effects to be secondary. The normal criterion for the onset of water waves under terrestrial conditions is extended to recognize the greater atmospheric viscous boundary layer depth for low atmospheric pressures. We used terrestrial wave models to predict the wave environment expected for reasonable ranges of atmospheric pressure and wind for end-member cases of ocean salinity. These models were modified only to reflect the different fluids considered at Mars, the different martian surface gravity, and the varying atmospheric pressure, wind and fetch. The models were favorably validated against one another, and also against experiments conducted in a wave tank in a pressure controlled wind tunnel (NASA Ames MARSWIT). We conclude that if wave-cut shorelines can be confirmed on Mars, this can constrain the range of possible atmospheric pressures and wind speeds that could have existed when the open water was present on Mars.

Model improvements and validation of TerraSAR-X precise orbit determination

NASA Astrophysics Data System (ADS)

Hackel, S.; Montenbruck, O.; Steigenberger, P.; Balss, U.; Gisinger, C.; Eineder, M.

2017-05-01

The radar imaging satellite mission TerraSAR-X requires precisely determined satellite orbits for validating geodetic remote sensing techniques. Since the achieved quality of the operationally derived, reduced-dynamic (RD) orbit solutions limits the capabilities of the synthetic aperture radar (SAR) validation, an effort is made to improve the estimated orbit solutions. This paper discusses the benefits of refined dynamical models on orbit accuracy as well as estimated empirical accelerations and compares different dynamic models in a RD orbit determination. Modeling aspects discussed in the paper include the use of a macro-model for drag and radiation pressure computation, the use of high-quality atmospheric density and wind models as well as the benefit of high-fidelity gravity and ocean tide models. The Sun-synchronous dusk-dawn orbit geometry of TerraSAR-X results in a particular high correlation of solar radiation pressure modeling and estimated normal-direction positions. Furthermore, this mission offers a unique suite of independent sensors for orbit validation. Several parameters serve as quality indicators for the estimated satellite orbit solutions. These include the magnitude of the estimated empirical accelerations, satellite laser ranging (SLR) residuals, and SLR-based orbit corrections. Moreover, the radargrammetric distance measurements of the SAR instrument are selected for assessing the quality of the orbit solutions and compared to the SLR analysis. The use of high-fidelity satellite dynamics models in the RD approach is shown to clearly improve the orbit quality compared to simplified models and loosely constrained empirical accelerations. The estimated empirical accelerations are substantially reduced by 30% in tangential direction when working with the refined dynamical models. Likewise the SLR residuals are reduced from -3 ± 17 to 2 ± 13 mm, and the SLR-derived normal-direction position corrections are reduced from 15 to 6 mm, obtained from the 2012-2014 period. The radar range bias is reduced from -10.3 to -6.1 mm with the updated orbit solutions, which coincides with the reduced standard deviation of the SLR residuals. The improvements are mainly driven by the satellite macro-model for the purpose of solar radiation pressure modeling, improved atmospheric density models, and the use of state-of-the-art gravity field models.

Large-scale experimental technology with remote sensing in land surface hydrology and meteorology

NASA Technical Reports Server (NTRS)

Brutsaert, Wilfried; Schmugge, Thomas J.; Sellers, Piers J.; Hall, Forrest G.

1988-01-01

Two field experiments to study atmospheric and land surface processes and their interactions are summarized. The Hydrologic-Atmospheric Pilot Experiment, which tested techniques for measuring evaporation, soil moisture storage, and runoff at scales of about 100 km, was conducted over a 100 X 100 km area in France from mid-1985 to early 1987. The first International Satellite Land Surface Climatology Program field experiment was conducted in 1987 to develop and use relationships between current satellite measurements and hydrologic, climatic, and biophysical variables at the earth's surface and to validate these relationships with ground truth. This experiment also validated surface parameterization methods for simulation models that describe surface processes from the scale of vegetation leaves up to scales appropriate to satellite remote sensing.

Software for Simulation of Hyperspectral Images

NASA Technical Reports Server (NTRS)

Richtsmeier, Steven C.; Singer-Berk, Alexander; Bernstein, Lawrence S.

2002-01-01

A package of software generates simulated hyperspectral images for use in validating algorithms that generate estimates of Earth-surface spectral reflectance from hyperspectral images acquired by airborne and spaceborne instruments. This software is based on a direct simulation Monte Carlo approach for modeling three-dimensional atmospheric radiative transport as well as surfaces characterized by spatially inhomogeneous bidirectional reflectance distribution functions. In this approach, 'ground truth' is accurately known through input specification of surface and atmospheric properties, and it is practical to consider wide variations of these properties. The software can treat both land and ocean surfaces and the effects of finite clouds with surface shadowing. The spectral/spatial data cubes computed by use of this software can serve both as a substitute for and a supplement to field validation data.

Simulation of Hyperspectral Images

NASA Technical Reports Server (NTRS)

Richsmeier, Steven C.; Singer-Berk, Alexander; Bernstein, Lawrence S.

2004-01-01

A software package generates simulated hyperspectral imagery for use in validating algorithms that generate estimates of Earth-surface spectral reflectance from hyperspectral images acquired by airborne and spaceborne instruments. This software is based on a direct simulation Monte Carlo approach for modeling three-dimensional atmospheric radiative transport, as well as reflections from surfaces characterized by spatially inhomogeneous bidirectional reflectance distribution functions. In this approach, "ground truth" is accurately known through input specification of surface and atmospheric properties, and it is practical to consider wide variations of these properties. The software can treat both land and ocean surfaces, as well as the effects of finite clouds with surface shadowing. The spectral/spatial data cubes computed by use of this software can serve both as a substitute for, and a supplement to, field validation data.

An evaluation of models of bare soil evaporation formulated with different land surface boundary conditions and assumptions

NASA Astrophysics Data System (ADS)

Smits, Kathleen M.; Ngo, Viet V.; Cihan, Abdullah; Sakaki, Toshihiro; Illangasekare, Tissa H.

2012-12-01

Bare soil evaporation is a key process for water exchange between the land and the atmosphere and an important component of the water balance. However, there is no agreement on the best modeling methodology to determine evaporation under different atmospheric boundary conditions. Also, there is a lack of directly measured soil evaporation data for model validation to compare these methods to establish the validity of their mathematical formulations. Thus, a need exists to systematically compare evaporation estimates using existing methods to experimental observations. The goal of this work is to test different conceptual and mathematical formulations that are used to estimate evaporation from bare soils to critically investigate various formulations and surface boundary conditions. Such a comparison required the development of a numerical model that has the ability to incorporate these boundary conditions. For this model, we modified a previously developed theory that allows nonequilibrium liquid/gas phase change with gas phase vapor diffusion to better account for dry soil conditions. Precision data under well-controlled transient heat and wind boundary conditions were generated, and results from numerical simulations were compared with experimental data. Results demonstrate that the approaches based on different boundary conditions varied in their ability to capture different stages of evaporation. All approaches have benefits and limitations, and no one approach can be deemed most appropriate for every scenario. Comparisons of different formulations of the surface boundary condition validate the need for further research on heat and vapor transport processes in soil for better modeling accuracy.

The Atmospheric Mercury Network: measurement and initial examination of an ongoing atmospheric mercury record across North America

NASA Astrophysics Data System (ADS)

Gay, D. A.; Schmeltz, D.; Prestbo, E.; Olson, M.; Sharac, T.; Tordon, R.

2013-04-01

The National Atmospheric Deposition Program (NADP) developed and operates a collaborative network of atmospheric mercury monitoring sites based in North America - the Atmospheric Mercury Network (AMNet). The justification for the network was growing interest and demand from many scientists and policy makers for a robust database of measurements to improve model development, assess policies and programs, and improve estimates of mercury dry deposition. Many different agencies and groups support the network, including federal, state, tribal, and international governments, academic institutions, and private companies. AMNet has added two high elevation sites outside of continental North America in Hawaii and Taiwan because of new partnerships forged within NADP. Network sites measure concentrations of atmospheric mercury fractions using automated, continuous mercury speciation systems. The procedures that NADP developed for field operations, data management, and quality assurance ensure that the network makes scientifically valid and consistent measurements. AMNet reports concentrations of hourly gaseous elemental mercury (GEM), two-hour gaseous oxidized mercury (GOM), and two-hour particulate-bound mercury less than 2.5 microns in size (PBM2.5). As of January 2012, over 450 000 valid observations are available from 30 stations. The AMNet also collects ancillary meteorological data and information on land-use and vegetation, when available. We present atmospheric mercury data comparisons by time (3 yr) at 22 unique site locations. Highlighted are contrasting values for site locations across the network: urban versus rural, coastal versus high-elevation and the range of maximum observations. The data presented should catalyze the formation of many scientific questions that may be answered through further in-depth analysis and modeling studies of the AMNet database. All data and methods are publically available through an online database on the NADP website (http://nadp.isws.illinois.edu/amn/). Future network directions are to foster new network partnerships and continue to collect, quality assure, and post data, including dry deposition estimates, for each fraction.

The Atmospheric Mercury Network: measurement and initial examination of an ongoing atmospheric mercury record across North America

NASA Astrophysics Data System (ADS)

Gay, D. A.; Schmeltz, D.; Prestbo, E.; Olson, M.; Sharac, T.; Tordon, R.

2013-11-01

The National Atmospheric Deposition Program (NADP) developed and operates a collaborative network of atmospheric-mercury-monitoring sites based in North America - the Atmospheric Mercury Network (AMNet). The justification for the network was growing interest and demand from many scientists and policy makers for a robust database of measurements to improve model development, assess policies and programs, and improve estimates of mercury dry deposition. Many different agencies and groups support the network, including federal, state, tribal, and international governments, academic institutions, and private companies. AMNet has added two high-elevation sites outside of continental North America in Hawaii and Taiwan because of new partnerships forged within NADP. Network sites measure concentrations of atmospheric mercury fractions using automated, continuous mercury speciation systems. The procedures that NADP developed for field operations, data management, and quality assurance ensure that the network makes scientifically valid and consistent measurements. AMNet reports concentrations of hourly gaseous elemental mercury (GEM), two-hour gaseous oxidized mercury (GOM), and two-hour particulate-bound mercury less than 2.5 microns in size (PBM2.5). As of January 2012, over 450 000 valid observations are available from 30 stations. AMNet also collects ancillary meteorological data and information on land use and vegetation, when available. We present atmospheric mercury data comparisons by time (3 yr) at 21 individual sites and instruments. Highlighted are contrasting values for site locations across the network: urban versus rural, coastal versus high elevation and the range of maximum observations. The data presented should catalyze the formation of many scientific questions that may be answered through further in-depth analysis and modeling studies of the AMNet database. All data and methods are publically available through an online database on the NADP website (http://nadp.sws.uiuc.edu/amn/). Future network directions are to foster new network partnerships and continue to collect, quality assure, and post data, including dry deposition estimates, for each fraction.

InSAR atmospheric correction using Himawari-8 Geostationary Meteorological Satellite

NASA Astrophysics Data System (ADS)

Kinoshita, Y.; Nimura, T.; Furuta, R.

2017-12-01

The atmospheric delay effect is one of the limitations for the accurate surface displacement detection by Synthetic Aperture Radar Interferometry (InSAR). Many previous studies have attempted to mitigate the neutral atmospheric delay in InSAR (e.g. Jolivet et al. 2014; Foster et al. 2006; Kinoshita et al. 2013). Hanssen et al. (2001) investigated the relationship between the 27 hourly observations of GNSS precipitable water vapor (PWV) and the infrared brightness temperature derived from visible satellite imagery, and showed a good correlation. Here we showed a preliminary result of the newly developed method for the neutral atmospheric delay correction using the Himawari-8 Japanese geostationary meteorological satellite data. The Himawari-8 satellite is the Japanese state-of-the-art geostationary meteorological satellite that has 16 observation channels and has spatial resolutions of 0.5 km (visible) and 2.0 km (near-infrared and infrared) with an time interval of 2.5 minutes around Japan. To estimate the relationship between the satellite brightness temperature and the atmospheric delay amount. Since the InSAR atmospheric delay is principally the same as that in GNSS, we at first compared the Himawari-8 data with the GNSS zenith tropospheric delay data derived from the Japanese dense GNSS network. The comparison of them showed that the band with the wavelength of 6.9 μm had the highest correlation to the GNSS observation. Based on this result, we developed an InSAR atmospheric delay model that uses the Himawari-8 6.9 μm band data. For the model validation, we generated InSAR images from the ESA's C-band Sentinel-1 SLC data with the GAMMA SAR software. We selected two regions around Tokyo and Sapporo (both in Japan) as the test sites because of the less temporal decorrelation. The validation result showed that the delay model reasonably estimate large scale phase variation whose spatial scale was on the order of over 20 km. On the other hand, phase variations of a few km scale were not estimated by the model. This would be due to the horizontal resolution of the input data (2 km in the 6.9 μm band). In the presentation we will show these results and the progress after the abstract submission, and discuss the limitation of our method and the future research plan.

Photochemistry, Ion Chemistry, and Haze Formation in Pluto’s Atmosphere

NASA Astrophysics Data System (ADS)

Summers, Michael E.; Stern, S. A.; Gladstone, G. Randal; Young, Leslie A.; Olkin, C. B.; Weaver, H. A.; Cheng, A. F.; Strobel, D. F.; Ennico, K. A.; Kammer, J. A.; Parker, A. H.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A. J.; Tsang, C. C.; Versteeg, M. H.; Greathouse, T. K.; Linscott, I. R.; Tyler, L. G.; Woods, W. W.; Hinson, D. P.; Parker, J. W.; Renaud, J. P.; Ewell, M.; Lisse, Cary M.

2015-11-01

The detection of ethylene (C2H4) and acetylene (C2H2) in Pluto’s atmosphere provides important ground-truth observations for validating photochemical models of Pluto’s atmosphere. Their detection also confirms the production of precursor chemical compounds involved in the formation of tholins, which are thought to give Pluto’s surface its reddish color. Photochemical models predict many other hydrocarbon and nitrile products, currently undetected, which may also be participants in tholin production on Pluto’s surface or on atmospheric haze particles. The observed atmospheric haze layer extending to altitudes of ~140 km above Pluto’s surface, suggests a global and very robust process of atmospheric particle nucleation, growth, and sedimentation onto Pluto’s surface. The high altitude extent of the haze layer suggests that the nucleation process begins above the expected altitude range where hydrocarbons become supersaturated (below ~30 km altitude). This situation may be analogous to that in Titan’s atmosphere, wherein nucleation and aerosol growth is directly related to large negative ion production. In the case of Pluto, this means that nucleation may occur at altitudes as high as 1200 km altitude where ionization in Pluto’s atmosphere peaks. In this paper we discuss these processes and their implications for haze formation in Pluto’s atmosphere and its deposition onto Pluto’s surface. This work was supported by NASA's New Horizons project.

Global Modelling of the total OH reactivity: validation against measurements and atmospheric implications of the 'missing' sink

NASA Astrophysics Data System (ADS)

Ferracci, Valerio; Archibald, Alexander T.; Pyle, John A.

2017-04-01

The removal of most trace gases emitted into the atmosphere is primarily initiated by reaction with the hydroxyl radical, OH. A number of field campaigns over the last two decades have observed the presence of a "missing" sink of the OH radical in a variety of regions across the planet, from urban areas to remote forests: comparison of the direct measurements of the OH loss rate, also known as total OH reactivity, with the sum of individual known OH sinks (obtained via the simultaneous detection of species such as volatile organic compounds and nitrogen oxides) indicated that, in some cases, up to 80% of the total OH loss rate was unaccounted for. The implications of this finding are significant, as a potentially major OH sink operating in the atmosphere is not currently accounted for in atmospheric models: the presence of an additional OH sink might, for instance, lead to an increase in the atmospheric lifetime of a number of trace species, including high-impact greenhouse gases such as methane. The only modelling of the total OH reactivity is currently performed on a regional scale; a thorough assessment of the impact of the missing sink on the chemistry and climate of the planet by global modelling is therefore highly desirable. In this work a chemistry-climate model (the Met Office's Unified Model with the United Kingdom Chemistry and Aerosols scheme, UM-UKCA) was used to calculate the total OH reactivity at the planetary boundary layer. The model output was validated against available field measurements to verify that the known OH sinks observed in the field were reproduced correctly by the model: a good agreement was found between the data from more than 30 field campaigns and the model output. Following this, the effects of introducing novel OH sinks in the chemistry scheme were investigated. The first step was the introduction in the model of the newly characterised reactions of peroxy radicals (RO2) with OH, the kinetics and products of which have only recently been studied in the laboratory. Results from the UM-UKCA model show that reaction with RO2 might represent a non-negligible OH sink in remote environments, but cannot reconcile field measurements of the total OH reactivity with the sum of the individual sinks. To address this, an unspecified additional sink was added to the model in a series of simulations reproducing different scenarios (e.g., different OH recycling probabilities through the oxidation of the additional sink) with a view to establishing the impact of the additional OH sink on the oxidative capacity of the lower atmosphere.

Real-time Retrieving Atmospheric Parameters from Multi-GNSS Constellations

NASA Astrophysics Data System (ADS)

Li, X.; Zus, F.; Lu, C.; Dick, G.; Ge, M.; Wickert, J.; Schuh, H.

2016-12-01

The multi-constellation GNSS (e.g. GPS, GLONASS, Galileo, and BeiDou) bring great opportunities and challenges for real-time retrieval of atmospheric parameters for supporting numerical weather prediction (NWP) nowcasting or severe weather event monitoring. In this study, the observations from different GNSS are combined together for atmospheric parameter retrieving based on the real-time precise point positioning technique. The atmospheric parameters retrieved from multi-GNSS observations, including zenith total delay (ZTD), integrated water vapor (IWV), horizontal gradient (especially high-resolution gradient estimates) and slant total delay (STD), are carefully analyzed and evaluated by using the VLBI, radiosonde, water vapor radiometer and numerical weather model to independently validate the performance of individual GNSS and also demonstrate the benefits of multi-constellation GNSS for real-time atmospheric monitoring. Numerous results show that the multi-GNSS processing can provide real-time atmospheric products with higher accuracy, stronger reliability and better distribution, which would be beneficial for atmospheric sounding systems, especially for nowcasting of extreme weather.

Superconducting-Magnet-Based Faraday Rotation Spectrometer for Real Time in Situ Measurement of OH Radicals at 106 Molecule/cm3 Level in an Atmospheric Simulation Chamber.

PubMed

Zhao, Weixiong; Fang, Bo; Lin, Xiaoxiao; Gai, Yanbo; Zhang, Weijun; Chen, Wenge; Chen, Zhiyou; Zhang, Haifeng; Chen, Weidong

2018-03-20

Atmospheric simulation chambers play vital roles in the validation of chemical mechanisms and act as a bridge between field measurements and modeling. Chambers operating at atmospheric levels of OH radicals (10 6 -10 7 molecule/cm 3 ) can significantly enhance the possibility for investigating the discrepancies between the observation and model predications. However, few chambers can directly detect chamber OH radicals at ambient levels. In this paper, we report on the first combination of a superconducting magnet with midinfrared Faraday rotation spectroscopy (FRS) for real time in situ measurement of the OH concentration in an atmospheric simulation chamber. With the use of a multipass enhanced FRS, a detection limit of 3.2 × 10 6 OH/cm 3 (2σ, 4 s) was achieved with an absorption path length of 108 m. The developed FRS system provided a unique, self-calibrated analytical instrument for in situ direct measurement of chamber OH concentration.

Validation of landsurface processes in the AMIP models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, T J

The Atmospheric Model Intercomparison Project (AMIP) is a commonly accepted protocol for testing the performance of the world's atmospheric general circulation models (AGCMs) under common specifications of radiative forcings (in solar constant and carbon dioxide concentration) and observed ocean boundary conditions (Gates 1992, Gates et al. 1999). From the standpoint of landsurface specialists, the AMIP affords an opportunity to investigate the behaviors of a wide variety of land-surface schemes (LSS) that are coupled to their ''native'' AGCMs (Phillips et al. 1995, Phillips 1999). In principle, therefore, the AMIP permits consideration of an overarching question: ''To what extent does an AGCM'smore » performance in simulating continental climate depend on the representations of land-surface processes by the embedded LSS?'' There are, of course, some formidable obstacles to satisfactorily addressing this question. First, there is the dilemna of how to effectively validate simulation performance, given the present dearth of global land-surface data sets. Even if this data problem were to be alleviated, some inherent methodological difficulties would remain: in the context of the AMIP, it is not possible to validate a given LSS per se, since the associated land-surface climate simulation is a product of the coupled AGCM/LSS system. Moreover, aside from the intrinsic differences in LSS across the AMIP models, the varied representations of land-surface characteristics (e.g. vegetation properties, surface albedos and roughnesses, etc.) and related variations in land-surface forcings further complicate such an attribution process. Nevertheless, it may be possible to develop validation methodologies/statistics that are sufficiently penetrating to reveal ''signatures'' of particular ISS representations (e.g. ''bucket'' vs more complex parameterizations of hydrology) in the AMIP land-surface simulations.« less

Demonstrating the Alaska Ocean Observing System in Prince William Sound

NASA Astrophysics Data System (ADS)

Schoch, G. Carl; McCammon, Molly

2013-07-01

The Alaska Ocean Observing System and the Oil Spill Recovery Institute developed a demonstration project over a 5 year period in Prince William Sound. The primary goal was to develop a quasi-operational system that delivers weather and ocean information in near real time to diverse user communities. This observing system now consists of atmospheric and oceanic sensors, and a new generation of computer models to numerically simulate and forecast weather, waves, and ocean circulation. A state of the art data management system provides access to these products from one internet portal at http://www.aoos.org. The project culminated in a 2009 field experiment that evaluated the observing system and performance of the model forecasts. Observations from terrestrial weather stations and weather buoys validated atmospheric circulation forecasts. Observations from wave gages on weather buoys validated forecasts of significant wave heights and periods. There was an emphasis on validation of surface currents forecasted by the ocean circulation model for oil spill response and search and rescue applications. During the 18 day field experiment a radar array mapped surface currents and drifting buoys were deployed. Hydrographic profiles at fixed stations, and by autonomous vehicles along transects, were made to acquire measurements through the water column. Terrestrial weather stations were the most reliable and least costly to operate, and in situ ocean sensors were more costly and considerably less reliable. The radar surface current mappers were the least reliable and most costly but provided the assimilation and validation data that most improved ocean circulation forecasts. We describe the setting of Prince William Sound and the various observational platforms and forecast models of the observing system, and discuss recommendations for future development.

Can we use modelling methodologies to assess airborne benzo[a]pyrene from biomonitors? A comprehensive evaluation approach

NASA Astrophysics Data System (ADS)

Ratola, N.; Jiménez-Guerrero, P.

2015-09-01

Biomonitoring data available on levels of atmospheric polycyclic aromatic hydrocarbons (PAHs) in pine needles from the Iberian Peninsula was used to estimate air concentrations of benzo[a]pyrene (BaP) and, at the same time, fuelled the comparison with chemistry transport model representations. Simulations with the modelling system WRF + CHIMERE were validated against data from the European Monitoring and Evaluation Programme (EMEP) air sampling network and using modelled atmospheric concentrations as a consistent reference in order to compare the performance of vegetation-to-air estimating methods. A spatial and temporal resolution of 9 km and 1 h was implemented. The field-based database relied on a pine needles sampling scheme comprising 33 sites in Portugal and 37 sites in Spain complemented with the BaP measurements available from the EMEP sites. The ability of pine needles to act as biomonitoring markers for the atmospheric concentrations of BaP was estimated converting the levels obtained in pine needles into air concentrations by six different approaches, one of them presenting realistic concentrations when compared to the modelled atmospheric values. The justification for this study is the gaps still existing in the knowledge of the life cycles of semi-volatile organic compounds (SVOCs), particularly the partition processes between air and vegetation. The strategy followed in this work allows the definition of the transport patterns (e.g. dispersion) established by the model for atmospheric concentrations and the estimated values in vegetation.

Initial Retrieval Validation from the Joint Airborne IASI Validation Experiment (JAIVEx)

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Smith, WIlliam L.; Larar, Allen M.; Taylor, Jonathan P.; Revercomb, Henry E.; Mango, Stephen A.; Schluessel, Peter; Calbet, Xavier

2007-01-01

The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite, but also included a strong component focusing on validation of the Atmospheric InfraRed Sounder (AIRS) aboard the AQUA satellite. The cross validation of IASI and AIRS is important for the joint use of their data in the global Numerical Weather Prediction process. Initial inter-comparisons of geophysical products have been conducted from different aspects, such as using different measurements from airborne ultraspectral Fourier transform spectrometers (specifically, the NPOESS Airborne Sounder Testbed Interferometer (NAST-I) and the Scanning-High resolution Interferometer Sounder (S-HIS) aboard the NASA WB-57 aircraft), UK Facility for Airborne Atmospheric Measurements (FAAM) BAe146-301 aircraft insitu instruments, dedicated dropsondes, radiosondes, and ground based Raman Lidar. An overview of the JAIVEx retrieval validation plan and some initial results of this field campaign are presented.

BaP (PAH) air quality modelling exercise over Zaragoza (Spain) using an adapted version of WRF-CMAQ model.

PubMed

San José, Roberto; Pérez, Juan Luis; Callén, María Soledad; López, José Manuel; Mastral, Ana

2013-12-01

Benzo(a)pyrene (BaP) is one of the most dangerous PAH due to its high carcinogenic and mutagenic character. Because of this reason, the Directive 2004/107/CE of the European Union establishes a target value of 1 ng/m(3) of BaP in the atmosphere. In this paper, the main aim is to estimate the BaP concentrations in the atmosphere by using last generation of air quality dispersion models with the inclusion of the transport, scavenging and deposition processes for the BaP. The degradation of the particulated BaP by the ozone has been considered. The aerosol-gas partitioning phenomenon in the atmosphere is modelled taking into a count that the concentrations in the gas and the aerosol phases. If the pre-existing organic aerosol concentrations are zero gas/particle equilibrium is established. The model has been validated at local scale with data from a sampling campaign carried out in the area of Zaragoza (Spain) during 12 weeks. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Unmanned Aerial System SUMO: an alternative measurement tool for polar boundary layer studies

NASA Astrophysics Data System (ADS)

Mayer, S.; Jonassen, M. O.; Reuder, J.

2012-04-01

Numerical weather prediction and climate models face special challenges in particular in the commonly stable conditions in the high-latitude environment. For process studies as well as for model validation purposes in-situ observations in the atmospheric boundary layer are highly required, but difficult to retrieve. We introduce a new measurement system for corresponding observations. The Small Unmanned Meteorological Observer SUMO consists of a small and light-weight auto-piloted model aircraft, equipped with a meteorological sensor package. SUMO has been operated in polar environments, among others during IPY on Spitsbergen in the year 2009 and has proven its capabilities for atmospheric measurements with high spatial and temporal resolution even at temperatures of -30 deg C. A comparison of the SUMO data with radiosondes and tethered balloons shows that SUMO can provide atmospheric profiles with comparable quality to those well-established systems. Its high data quality allowed its utilization for evaluation purposes of high-resolution model runs performed with the Weather Research and Forecasting model WRF and for the detailed investigation of an orographically modified flow during a case study.

Assessment of Biases in MODIS Surface Reflectance Due to Lambertian Approximation

NASA Technical Reports Server (NTRS)

Wang, Yujie; Lyapustin, Alexei I.; Privette, Jeffrey L.; Cook, Robert B.; SanthanaVannan, Suresh K.; Vermote, Eric F.; Schaaf, Crystal

2010-01-01

Using MODIS data and the AERONET-based Surface Reflectance Validation Network (ASRVN), this work studies errors of MODIS atmospheric correction caused by the Lambertian approximation. On one hand, this approximation greatly simplifies the radiative transfer model, reduces the size of the look-up tables, and makes operational algorithm faster. On the other hand, uncompensated atmospheric scattering caused by Lambertian model systematically biases the results. For example, for a typical bowl-shaped bidirectional reflectance distribution function (BRDF), the derived reflectance is underestimated at high solar or view zenith angles, where BRDF is high, and is overestimated at low zenith angles where BRDF is low. The magnitude of biases grows with the amount of scattering in the atmosphere, i.e., at shorter wavelengths and at higher aerosol concentration. The slope of regression of Lambertian surface reflectance vs. ASRVN bidirectional reflectance factor (BRF) is about 0.85 in the red and 0.6 in the green bands. This error propagates into the MODIS BRDF/albedo algorithm, slightly reducing the magnitude of overall reflectance and anisotropy of BRDF. This results in a small negative bias of spectral surface albedo. An assessment for the GSFC (Greenbelt, USA) validation site shows the albedo reduction by 0.004 in the near infrared, 0.005 in the red, and 0.008 in the green MODIS bands.

Coastal Atmosphere and Sea Time Series (CoASTS)

NASA Technical Reports Server (NTRS)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Zibordi, Giuseppe; Berthon, Jean-Francoise; Doyle, John P.; Grossi, Stefania; vanderLinde, Dirk; Targa, Cristina; Alberotanza, Luigi; McClain, Charles R. (Technical Monitor)

2002-01-01

The Coastal Atmosphere and Sea Time Series (CoASTS) Project aimed at supporting ocean color research and applications, from 1995 up to the time of publication of this document, has ensured the collection of a comprehensive atmospheric and marine data set from an oceanographic tower located in the northern Adriatic Sea. The instruments and the measurement methodologies used to gather quantities relevant for bio-optical modeling and for the calibration and validation of ocean color sensors, are described. Particular emphasis is placed on four items: (1) the evaluation of perturbation effects in radiometric data (i.e., tower-shading, instrument self-shading, and bottom effects); (2) the intercomparison of seawater absorption coefficients from in situ measurements and from laboratory spectrometric analysis on discrete samples; (3) the intercomparison of two filter techniques for in vivo measurement of particulate absorption coefficients; and (4) the analysis of repeatability and reproducibility of the most relevant laboratory measurements carried out on seawater samples (i.e., particulate and yellow substance absorption coefficients, and pigment and total suspended matter concentrations). Sample data are also presented and discussed to illustrate the typical features characterizing the CoASTS measurement site in view of supporting the suitability of the CoASTS data set for bio-optical modeling and ocean color calibration and validation.

Solar system neighbors as proxies for exoplanets; Peering through the atmospheres of Titan and Saturn with Cassini

NASA Astrophysics Data System (ADS)

Teal, Dillon J.; Fortney, Jonathan J.; Line, Michael R.

2016-10-01

A transiting exoplanet is a planet that orbits another star, and periodically passes directly in front of its parent star, blocking out a small fraction of the stellar light. We can study the atmospheres of these planets by looking at the tiny fraction of the star's light that passes through the planet's thin outer atmosphere, called a transmission spectrum. This is one of the few ways to probe an exoplanet's atmosphere with current technology. This field will rapidly expand with the launch of the Transiting Exoplanet Survey System (TESS) in 2017, to find more planets, and the James Webb Space Telescope (JWST) in 2018, to characterize exoplanet atmospheres. The need to validate the models we use to calculate exoplanet atmosphere properties in the regime of high signal-to-noise data has become increasingly important. Thankfully, with the help of NASA's Cassini orbiter we can test our transmission spectra models against transmission spectra of real planetary bodies for which we have "ground truth" measurements. Using the CHIMERA Transmission spectra model of Line et al. (2013a) and the Python multinesting framework pyMultinest, from the Saturn and Titan transmission spectra we retrieve the abundances of the important molecules CH4, CO, CO2, NH3, and C2H2 along with atmospheric temperature, a reference or "surface" pressure, and the cloud pressure. Here we discuss the current status of this work, and potential problems facing our models, including a C-H stretching feature between 3-4 microns and haze scattering.

Design and validation of MEDRYS, a Mediterranean Sea reanalysis over the period 1992-2013

NASA Astrophysics Data System (ADS)

Hamon, Mathieu; Beuvier, Jonathan; Somot, Samuel; Lellouche, Jean-Michel; Greiner, Eric; Jordà, Gabriel; Bouin, Marie-Noëlle; Arsouze, Thomas; Béranger, Karine; Sevault, Florence; Dubois, Clotilde; Drevillon, Marie; Drillet, Yann

2016-04-01

The French research community in the Mediterranean Sea modeling and the French operational ocean forecasting center Mercator Océan have gathered their skill and expertise in physical oceanography, ocean modeling, atmospheric forcings and data assimilation to carry out a MEDiterranean sea ReanalYsiS (MEDRYS) at high resolution for the period 1992-2013. The ocean model used is NEMOMED12, a Mediterranean configuration of NEMO with a 1/12° ( ˜ 7 km) horizontal resolution and 75 vertical z levels with partial steps. At the surface, it is forced by a new atmospheric-forcing data set (ALDERA), coming from a dynamical downscaling of the ERA-Interim atmospheric reanalysis by the regional climate model ALADIN-Climate with a 12 km horizontal and 3 h temporal resolutions. This configuration is used to carry a 34-year hindcast simulation over the period 1979-2013 (NM12-FREE), which is the initial state of the reanalysis in October 1992. MEDRYS uses the existing Mercator Océan data assimilation system SAM2 that is based on a reduced-order Kalman filter with a three-dimensional (3-D) multivariate modal decomposition of the forecast error. Altimeter data, satellite sea surface temperature (SST) and temperature and salinity vertical profiles are jointly assimilated. This paper describes the configuration we used to perform MEDRYS. We then validate the skills of the data assimilation system. It is shown that the data assimilation restores a good average temperature and salinity at intermediate layers compared to the hindcast. No particular biases are identified in the bottom layers. However, the reanalysis shows slight positive biases of 0.02 psu and 0.15 °C above 150 m depth. In the validation stage, it is also shown that the assimilation allows one to better reproduce water, heat and salt transports through the Strait of Gibraltar. Finally, the ability of the reanalysis to represent the sea surface high-frequency variability is shown.

Utilization of UARS Data in Validation of Photochemical and Dynamical Mechanisms in Stratospheric Models

NASA Technical Reports Server (NTRS)

Ko, M. K. W.; Rodriquez, J. M.; Hu, W.; Danilin, M. Y.; Shia, R.-L.

1998-01-01

The proposed work utilized Upper Atmosphere Research Satellite (UARS) measurements of short-lived and long-lived species, in conjunction with existing photochemical "box" models, trajectory models, and two-dimensional global models, to elucidate outstanding questions in our understanding of photochemical and dynamical mechanisms in the stratosphere. Particular emphasis was given to arriving at the best possible understanding of the chemical and dynamical contributions to the stratospheric ozone budget. Such understanding will increase confidence in the simulations carried out by assessment models.

Utilization of UARS Data in Validation of Photochemical and Dynamical Mechanisms in Stratospheric Models

NASA Technical Reports Server (NTRS)

Ko, Malcolm K. W.; Rodriquez, Jose M.; Hu, Wenjie; Danilin, Michael Y.; Shia, Run-Li

1998-01-01

The proposed work utilized Upper Atmosphere Research Satellite (UARS) measurements of short-lived and long-lived species, in conjunction with existing photochemical "box" models, trajectory models, and two-dimensional global models, to elucidate outstanding questions in our understanding of photochemical and dynamical mechanisms in the stratosphere. Particular emphasis was given to arriving at the best possible understanding of the chemical and dynamical contribution to the stratospheric ozone budget. Such understanding will increase confidence in the simulations carried out by assessment models.

A principal component regression model to forecast airborne concentration of Cupressaceae pollen in the city of Granada (SE Spain), during 1995-2006.

PubMed

Ocaña-Peinado, Francisco M; Valderrama, Mariano J; Bouzas, Paula R

2013-05-01

The problem of developing a 2-week-on ahead forecast of atmospheric cypress pollen levels is tackled in this paper by developing a principal component multiple regression model involving several climatic variables. The efficacy of the proposed model is validated by means of an application to real data of Cupressaceae pollen concentration in the city of Granada (southeast of Spain). The model was applied to data from 11 consecutive years (1995-2005), with 2006 being used to validate the forecasts. Based on the work of different authors, factors as temperature, humidity, hours of sun and wind speed were incorporated in the model. This methodology explains approximately 75-80% of the variability in the airborne Cupressaceae pollen concentration.

Aerosol physicochemical properties in relation to meteorology: Case studies in urban, marine, and arid settings

NASA Astrophysics Data System (ADS)

Wonaschuetz, Anna

Atmospheric aerosols are a highly relevant component of the climate system affecting atmospheric radiative transfer and the hydrological cycle. As opposed to other key atmospheric constituents with climatic relevance, atmospheric aerosol particles are highly heterogeneous in time and space with respect to their size, concentration, chemical composition and physical properties. Many aspects of their life cycle are not understood, making them difficult to represent in climate models and hard to control as a pollutant. Aerosol-cloud interactions in particular are infamous as a major source of uncertainty in future climate predictions. Field measurements are an important source of information for the modeling community and can lead to a better understanding of chemical and microphysical processes. In this study, field data from urban, marine, and arid settings are analyzed and the impact of meteorological conditions on the evolution of aerosol particles while in the atmosphere is investigated. Particular attention is given to organic aerosols, which are a poorly understood component of atmospheric aerosols. Local wind characteristics, solar radiation, relative humidity and the presence or absence of clouds and fog are found to be crucial factors in the transport and chemical evolution of aerosol particles. Organic aerosols in particular are found to be heavily impacted by processes in the liquid phase (cloud droplets and aerosol water). The reported measurements serve to improve the process-level understanding of aerosol evolution in different environments and to inform the modeling community by providing realistic values for input parameters and validation of model calculations.

Solar Radiation Estimated Through Mesoscale Atmospheric Modeling over Northeast Brazil

NASA Astrophysics Data System (ADS)

de Menezes Neto, Otacilio Leandro; Costa, Alexandre Araújo; Ramalho, Fernando Pinto; de Maria, Paulo Henrique Santiago

2009-03-01

The use of renewable energy sources, like solar, wind and biomass is rapidly increasing in recent years, with solar radiation as a particularly abundant energy source over Northeast Brazil. A proper quantitative knowledge of the incoming solar radiation is of great importance for energy planning in Brazil, serving as basis for developing future projects of photovoltaic power plants and solar energy exploitation. This work presents a methodology for mapping the incoming solar radiation at ground level for Northeast Brazil, using a mesoscale atmospheric model (Regional Atmospheric Modeling System—RAMS), calibrated and validated using data from the network of automatic surface stations from the State Foundation for Meteorology and Water Resources from Ceará (Fundação Cearense de Meteorologia e Recursos Hídricos- FUNCEME). The results showed that the model exhibits systematic errors, overestimating surface radiation, but that, after the proper statistical corrections, using a relationship between the model-predicted cloud fraction, the ground-level observed solar radiation and the incoming solar radiation estimated at the top of the atmosphere, a correlation of 0.92 with a confidence interval of 13.5 W/m2 is found for monthly data. Using this methodology, we found an estimate for annual average incoming solar radiation over Ceará of 215 W/m2 (maximum in October: 260 W/m2).

Atmospheric water mapping with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), Mountain Pass, California

NASA Technical Reports Server (NTRS)

Conel, James E.; Green, Robert O.; Carrere, Veronique; Margolis, Jack S.; Alley, Ronald E.; Vane, Gregg; Bruegge, Carol J.; Gary, Bruce L.

1988-01-01

Observations are given of the spatial variation of atmospheric precipitable water using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over a desert area in eastern California, derived using a band ratio method and the 940 nm atmospheric water band and 870 nm continuum radiances. The ratios yield total path water from curves of growth supplied by the LOWTRAN 7 atmospheric model. An independent validation of the AVIRIS-derived column abundance at a point is supplied by a spectral hygrometer calibrated with respect to radiosonde observations. Water values conform to topography and fall off with surface elevation. The edge of the water vapor boundary layer defined by topography is thought to have been recovered. The ratio method yields column abundance estimates of good precision and high spatial resolution.

Modeling the Surface Temperature of Earth-like Planets

NASA Astrophysics Data System (ADS)

Vladilo, Giovanni; Silva, Laura; Murante, Giuseppe; Filippi, Luca; Provenzale, Antonello

2015-05-01

We introduce a novel Earth-like planet surface temperature model (ESTM) for habitability studies based on the spatial-temporal distribution of planetary surface temperatures. The ESTM adopts a surface energy balance model (EBM) complemented by: radiative-convective atmospheric column calculations, a set of physically based parameterizations of meridional transport, and descriptions of surface and cloud properties more refined than in standard EBMs. The parameterization is valid for rotating terrestrial planets with shallow atmospheres and moderate values of axis obliquity (ɛ ≲ 45{}^\\circ ). Comparison with a 3D model of atmospheric dynamics from the literature shows that the equator-to-pole temperature differences predicted by the two models agree within ≈ 5 K when the rotation rate, insolation, surface pressure and planet radius are varied in the intervals 0.5≲ {Ω }/{{{Ω }}\\oplus }≲ 2, 0.75≲ S/{{S}\\circ }≲ 1.25, 0.3≲ p/(1 bar)≲ 10, and 0.5≲ R/{{R}\\oplus }≲ 2, respectively. The ESTM has an extremely low computational cost and can be used when the planetary parameters are scarcely known (as for most exoplanets) and/or whenever many runs for different parameter configurations are needed. Model simulations of a test-case exoplanet (Kepler-62e) indicate that an uncertainty in surface pressure within the range expected for terrestrial planets may impact the mean temperature by ˜ 60 K. Within the limits of validity of the ESTM, the impact of surface pressure is larger than that predicted by uncertainties in rotation rate, axis obliquity, and ocean fractions. We discuss the possibility of performing a statistical ranking of planetary habitability taking advantage of the flexibility of the ESTM.

Climate Change Impacts for Conterminous USA: An Integrated Assessment Part 2. Models and Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomson, Allison M.; Rosenberg, Norman J.; Izaurralde, R Cesar C.

As CO{sub 2} and other greenhouse gases accumulate in the atmosphere and contribute to rising global temperatures, it is important to examine how a changing climate may affect natural and managed ecosystems. In this series of papers, we study the impacts of climate change on agriculture, water resources and natural ecosystems in the conterminous United States using a suite of climate change predictions from General Circulation Models (GCMs) as described in Part 1. Here we describe the agriculture model EPIC and the HUMUS water model and validate them with historical crop yields and streamflow data. We compare EPIC simulated grainmore » and forage crop yields with historical crop yields from the US Department of Agriculture and find an acceptable level of agreement for this study. The validation of HUMUS simulated streamflow with estimates of natural streamflow from the US Geological Survey shows that the model is able to reproduce significant relationships and capture major trends.« less

Meteorology Research in DOE's Atmosphere to Electrons (A2e) Program

NASA Astrophysics Data System (ADS)

Cline, J.; Haupt, S. E.; Shaw, W. J.

2017-12-01

DOE's Atmosphere to electrons (A2e) program is performing cutting edge research to allow optimization of wind plants. This talk will summarize the atmospheric science portion of A2e, with an overview of recent and planned observation and modeling projects designed to bridge the terra incognita between the mesoscale and the microscales that affect wind plants. Introduction A2e is a major focus of the Wind Energy Technologies Office (WETO) within the Office of Energy Efficiency & Renewable Energy (EERE) at the DOE. The overall objective of A2e is to optimize wind power production and integrates improved knowledge of atmospheric inflow (fuel), turbine and plant aerodynamics, and control systems. The atmospheric component of the work addresses both the need for improved forecasting of hub-height winds and the need for improved turbulence characterization for turbine inflows under realistic atmospheric conditions and terrain. Several projects will be discussed to address observations of meteorological variables in regions not typically observed. The modelling needs are addressed through major multi-institutional integrated studies comprising both theoretical and numerical advances to improve models and field observations for physical insight. Model improvements are subjected to formal verification and validation, and numerical and observational data are archived and disseminated to the public through the A2e Data Archive and Portal (DAP; http://a2e.energy.gov). The overall outcome of this work will be increased annual energy production from wind plants and improved turbine lifetimes through a better understanding of atmospheric loading. We will briefly describe major components of the atmospheric part of the A2e strategy and work being done and planned.

An End-to-End simulator for the development of atmospheric corrections and temperature - emissivity separation algorithms in the TIR spectral domain

NASA Astrophysics Data System (ADS)

Rock, Gilles; Fischer, Kim; Schlerf, Martin; Gerhards, Max; Udelhoven, Thomas

2017-04-01

The development and optimization of image processing algorithms requires the availability of datasets depicting every step from earth surface to the sensor's detector. The lack of ground truth data obliges to develop algorithms on simulated data. The simulation of hyperspectral remote sensing data is a useful tool for a variety of tasks such as the design of systems, the understanding of the image formation process, and the development and validation of data processing algorithms. An end-to-end simulator has been set up consisting of a forward simulator, a backward simulator and a validation module. The forward simulator derives radiance datasets based on laboratory sample spectra, applies atmospheric contributions using radiative transfer equations, and simulates the instrument response using configurable sensor models. This is followed by the backward simulation branch, consisting of an atmospheric correction (AC), a temperature and emissivity separation (TES) or a hybrid AC and TES algorithm. An independent validation module allows the comparison between input and output dataset and the benchmarking of different processing algorithms. In this study, hyperspectral thermal infrared scenes of a variety of surfaces have been simulated to analyze existing AC and TES algorithms. The ARTEMISS algorithm was optimized and benchmarked against the original implementations. The errors in TES were found to be related to incorrect water vapor retrieval. The atmospheric characterization could be optimized resulting in increasing accuracies in temperature and emissivity retrieval. Airborne datasets of different spectral resolutions were simulated from terrestrial HyperCam-LW measurements. The simulated airborne radiance spectra were subjected to atmospheric correction and TES and further used for a plant species classification study analyzing effects related to noise and mixed pixels.

A systematic study of Rayleigh-Brillouin scattering in air, N₂, and O₂ gases.

PubMed

Gu, Ziyu; Ubachs, Wim

2014-09-14

Spontaneous Rayleigh-Brillouin scattering experiments in air, N2, and O2 have been performed for a wide range of temperatures and pressures at a wavelength of 403 nm and at a 90° scattering angle. Measurements of the Rayleigh-Brillouin spectral scattering profile were conducted at high signal-to-noise ratio for all three species, yielding high-quality spectra unambiguously showing the small differences between scattering in air, and its constituents N2 and O2. Comparison of the experimental spectra with calculations using the Tenti S6 model, developed in the 1970s based on linearized kinetic equations for molecular gases, demonstrates that this model is valid to high accuracy for N2 and O2, as well as for air. After previous measurements performed at 366 nm, the Tenti S6 model is here verified for a second wavelength of 403 nm, and for the pressure-temperature parameter space covered in the present study (250-340 K and 0.6-3 bars). In the application of the Tenti S6 model, based on the transport coefficients of the gases, such as thermal conductivity κ, internal specific heat capacity c(int) and shear viscosity η, as well as their temperature dependencies taken as inputs, values for the more elusive bulk viscosity η(b) for the gases are derived by optimizing the model to the measurements. It is verified that the bulk viscosity parameters obtained from previous experiments at 366 nm are valid for wavelengths of 403 nm. Also for air, which is treated as a single-component gas with effective gas transport coefficients, the Tenti S6 treatment is validated for 403 nm as for the previously used wavelength of 366 nm, yielding an accurate model description of the scattering profiles for a range of temperatures and pressures, including those of relevance for atmospheric studies. It is concluded that the Tenti S6 model, further verified in the present study, is applicable to LIDAR applications for exploring the wind velocity and the temperature profile distributions of the Earth's atmosphere. Based on the present findings at 90° scattering and the determination of η(b) values, predictions can be made on the spectral profiles for a typical LIDAR backscatter geometry. These Tenti S6 predictions for Rayleigh-Brillouin scattering deviate by some 7% from purely Gaussian profiles at realistic sub-atmospheric pressures occurring at 3-5 km altitude in the Earth's atmosphere.

Improved Orbit Determination and Forecasts with an Assimilative Tool for Atmospheric Density and Satellite Drag Specification

NASA Astrophysics Data System (ADS)

Crowley, G.; Pilinski, M.; Sutton, E. K.; Codrescu, M.; Fuller-Rowell, T. J.; Matsuo, T.; Fedrizzi, M.; Solomon, S. C.; Qian, L.; Thayer, J. P.

2016-12-01

Much as aircraft are affected by the prevailing winds and weather conditions in which they fly, satellites are affected by the variability in density and motion of the near earth space environment. Drastic changes in the neutral density of the thermosphere, caused by geomagnetic storms or other phenomena, result in perturbations of LEO satellite motions through drag on the satellite surfaces. This can lead to difficulties in locating important satellites, temporarily losing track of satellites, and errors when predicting collisions in space. We describe ongoing work to build a comprehensive nowcast and forecast system for specifying the neutral atmospheric state related to orbital drag conditions. The system outputs include neutral density, winds, temperature, composition, and the satellite drag derived from these parameters. This modeling tool is based on several state-of-the-art coupled models of the thermosphere-ionosphere as well as several empirical models running in real-time and uses assimilative techniques to produce a thermospheric nowcast. This software will also produce 72 hour predictions of the global thermosphere-ionosphere system using the nowcast as the initial condition and using near real-time and predicted space weather data and indices as the inputs. Features of this technique include: • Satellite drag specifications with errors lower than current models • Altitude coverage up to 1000km • Background state representation using both first principles and empirical models • Assimilation of satellite drag and other datatypes • Real time capability • Ability to produce 72-hour forecasts of the atmospheric state In this paper, we will summarize the model design and assimilative architecture, and present preliminary validation results. Validation results will be presented in the context of satellite orbit errors and compared with several leading atmospheric models including the High Accuracy Satellite Drag Model, which is currently used operationally by the Air Force to specify neutral densities. As part of the analysis, we compare the drag observed by a variety of satellites which were not used as part of the assimilation-dataset and whose perigee altitudes span a range from 200km to 700 km.

Spectral cumulus parameterization based on cloud-resolving model

NASA Astrophysics Data System (ADS)

Baba, Yuya

2018-02-01

We have developed a spectral cumulus parameterization using a cloud-resolving model. This includes a new parameterization of the entrainment rate which was derived from analysis of the cloud properties obtained from the cloud-resolving model simulation and was valid for both shallow and deep convection. The new scheme was examined in a single-column model experiment and compared with the existing parameterization of Gregory (2001, Q J R Meteorol Soc 127:53-72) (GR scheme). The results showed that the GR scheme simulated more shallow and diluted convection than the new scheme. To further validate the physical performance of the parameterizations, Atmospheric Model Intercomparison Project (AMIP) experiments were performed, and the results were compared with reanalysis data. The new scheme performed better than the GR scheme in terms of mean state and variability of atmospheric circulation, i.e., the new scheme improved positive bias of precipitation in western Pacific region, and improved positive bias of outgoing shortwave radiation over the ocean. The new scheme also simulated better features of convectively coupled equatorial waves and Madden-Julian oscillation. These improvements were found to be derived from the modification of parameterization for the entrainment rate, i.e., the proposed parameterization suppressed excessive increase of entrainment, thus suppressing excessive increase of low-level clouds.

Validation of Atmospheric Forcing Data for PIPS 3

DTIC Science & Technology

2001-09-30

members shortly. RESULTS Surface Temperature: Figure 1 shows a comparison of surface air temperatures from the NOGAPS model , the IABP and the NCEP...with some 8,000 daily velocity observations from the IABP buoys shows that the sea-ice model performs better when driven with NOGAPS surface stresses...forcing variables, surface radiative fluxes, surface winds, and precipitation estimates to be used in the development and operation of the PIPS 3.0 model

Spatial and Temporal Variability of Surface Energy Fluxes During Autumn Ice Advance: Observations and Model Validation

NASA Astrophysics Data System (ADS)

Persson, O. P. G.; Blomquist, B.; Grachev, A. A.; Guest, P. S.; Stammerjohn, S. E.; Solomon, A.; Cox, C. J.; Capotondi, A.; Fairall, C. W.; Intrieri, J. M.

2016-12-01

From Oct 4 to Nov 5, 2015, the Office of Naval Research - sponsored Sea State cruise in the Beaufort Sea with the new National Science Foundation R/V Sikuliaq obtained extensive in-situ and remote sensing observations of the lower troposphere, the advancing sea ice, wave state, and upper ocean conditions. In addition, a coupled atmosphere, sea ice, upper-ocean model, based on the RASM model, was run at NOAA/PSD in a hindcast mode for this same time period, providing a 10-day simulation of the atmosphere/ice/ocean evolution. Surface energy fluxes quantitatively represent the air-ice, air-ocean, and ice-ocean interaction processes, determining the cooling (warming) rate of the upper ocean and the growth (melting) rate of sea ice. These fluxes also impact the stratification of the lower troposphere and the upper ocean. In this presentation, both direct and indirect measurements of the energy fluxes during Sea State will be used to explore the spatial and temporal variability of these fluxes and the impacts of this variability on the upper ocean, ice, and lower atmosphere during the autumn ice advance. Analyses have suggested that these fluxes are impacted by atmospheric synoptic evolution, proximity to existing ice, ice-relative wind direction, ice thickness and snow depth. In turn, these fluxes impact upper-ocean heat loss and timing of ice formation, as well as stability in the lower troposphere and upper ocean, and hence heat transport to the free troposphere and ocean mixed-layer. Therefore, the atmospheric structure over the advancing first-year ice differs from that over the nearby open water. Finally, these observational analyses will be used to provide a preliminary validation of the spatial and temporal variability of the surface energy fluxes and the associated lower-tropospheric and upper-ocean structures in the simulations.

Three atmospheric dispersion experiments involving oil fog plumes measured by lidar

NASA Technical Reports Server (NTRS)

Eberhard, W. L.; Mcnice, G. T.; Troxel, S. W.

1986-01-01

The Wave Propagation Lab. participated with the U.S. Environmental Protection Agency in a series of experiments with the goal of developing and validating dispersion models that perform substantially better that models currently available. The lidar systems deployed and the data processing procedures used in these experiments are briefly described. Highlights are presented of conclusions drawn thus far from the lidar data.

Numerical simulation of "An American Haboob"

NASA Astrophysics Data System (ADS)

Vukovic, A.; Vujadinovic, M.; Pejanovic, G.; Andric, J.; Kumjian, M. R.; Djurdjevic, V.; Dacic, M.; Prasad, A. K.; El-Askary, H. M.; Paris, B. C.; Petkovic, S.; Nickovic, S.; Sprigg, W. A.

2013-10-01

A dust storm of fearful proportions hit Phoenix in the early evening hours of 5 July 2011. This storm, an American haboob, was predicted hours in advance because numerical, land-atmosphere modeling, computing power and remote sensing of dust events have improved greatly over the past decade. High resolution numerical models are required for accurate simulation of the small-scales of the haboob process, with high velocity surface winds produced by strong convection and severe downbursts. Dust productive areas in this region consist mainly of agricultural fields, with soil surfaces disturbed by plowing and tracks of land in the high Sonoran desert laid barren by ongoing draught. Model simulation of the 5 July 2011 dust storm uses the coupled atmospheric-dust model NMME-DREAM with 3.5 km horizontal resolution. A mask of the potentially dust productive regions is obtained from the land cover and the Normalized Difference Vegetation Index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). Model results are compared with radar and other satellite-based images and surface meteorological and PM10 observations. The atmospheric model successfully hindcasted the position of the front in space and time, with about 1 h late arrival in Phoenix. The dust model predicted the rapid uptake of dust and high values of dust concentration in the ensuing storm. South of Phoenix, over the closest source regions (~ 25 km), the model PM10 surface dust concentration reached ~ 2500 μg m-3, but underestimated the values measured by the PM10stations within the city. Model results are also validated by the MODIS aerosol optical depth (AOD), employing deep blue (DB) algorithms for aerosol loadings. Model validation included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), equipped with the lidar instrument, to disclose the vertical structure of dust aerosols as well as aerosol subtypes. Promising results encourage further research and application of high-resolution modeling and satellite-based remote sensing to warn of approaching severe dust events and reduce risks for safety and health.

Exploring uncertainty in the radiative budget of the Antarctic atmospheric boundary layer at Dome C

NASA Astrophysics Data System (ADS)

Veron, D. E.; Schroth, A.; Genthon, C.; Vignon, E.

2017-12-01

In the past two decades, significant advances have been made in observing and modeling the atmospheric boundary layer processes over the Eastern Antarctic plateau. However, there are gaps in understanding related to the radiative and moisture budgets in the very bottom of the ABL. Since 2009, continuous meteorological observations have been made at 6 heights in the bottom 40-m of the atmosphere as part of the CALibration and VAlidation of meteorological and climate models and satellite retrievals (C ALVA) campaign to improve understanding of the atmospheric state over Dome C. A recent case study that is part of the GEWEX Atmospheric Boundary Layer Study, GABLS4, has also focused on the ability of models to simulate stable summertime boundary layers at the same location. As part of the intercomparison, a model derived summertime climatology based on 10-years of PolarWRF simulations over the Eastern Antarctic plateau was developed. Comparisons between these simulations and data from the CALVA campaign suggest that PolarWRF is not capturing the small-scale variations in the longwave heating rate profile near the surface, and so predicts biased surface temperatures relative to observations. Additional work suggests that modifications of the surface snow representations may also be needed. Studies of the sensitivity of these results to changes in the moisture budget are ongoing.

Perceptions of Web Site Design Characteristics: A Malaysian/Australian Comparison.

ERIC Educational Resources Information Center

Fink, Dieter; Laupase, Ricky

2000-01-01

Compares the perceptions of Malaysians and Australians for four Web site design characteristics--atmospherics, news stories, signs, and products and services--as part of the integrated Internet marketing model. Hypothesizes that the predominant culture is not generalized to another culture, discusses validity and reliability, and suggest further…

Strong water absorption in the dayside emission spectrum of the planet HD 189733b.

PubMed

Grillmair, Carl J; Burrows, Adam; Charbonneau, David; Armus, Lee; Stauffer, John; Meadows, Victoria; van Cleve, Jeffrey; von Braun, Kaspar; Levine, Deborah

2008-12-11

Recent observations of the extrasolar planet HD 189733b did not reveal the presence of water in the emission spectrum of the planet. Yet models of such 'hot-Jupiter' planets predict an abundance of atmospheric water vapour. Validating and constraining these models is crucial to understanding the physics and chemistry of planetary atmospheres in extreme environments. Indications of the presence of water in the atmosphere of HD 189733b have recently been found in transmission spectra, where the planet's atmosphere selectively absorbs the light of the parent star, and in broadband photometry. Here we report the detection of strong water absorption in a high-signal-to-noise, mid-infrared emission spectrum of the planet itself. We find both a strong downturn in the flux ratio below 10 microm and discrete spectral features that are characteristic of strong absorption by water vapour. The differences between these and previous observations are significant and admit the possibility that predicted planetary-scale dynamical weather structures may alter the emission spectrum over time. Models that match the observed spectrum and the broadband photometry suggest that heat redistribution from the dayside to the nightside is weak. Reconciling this with the high nightside temperature will require a better understanding of atmospheric circulation or possible additional energy sources.

Space shuttle simulation model

NASA Technical Reports Server (NTRS)

Tatom, F. B.; Smith, S. R.

1980-01-01

The effects of atmospheric turbulence in both horizontal and near horizontal flight, during the return of the space shuttle, are important for determining design, control, and 'pilot-in-the-loop' effects. A nonrecursive model (based on von Karman spectra) for atmospheric turbulence along the flight path of the shuttle orbiter was developed which provides for simulation of instantaneous vertical and horizontal gusts at the vehicle center-of-gravity, and also for simulation of instantaneous gust gradients. Based on this model, the time series for both gusts and gust gradients were generated and stored on a series of magnetic tapes which are entitled shuttle simulation turbulence tapes (SSTT). The time series are designed to represent atmospheric turbulence from ground level to an altitude of 10,000 meters. The turbulence generation procedure is described as well as the results of validating the simulated turbulence. Conclusions and recommendations are presented and references cited. The tabulated one dimensional von Karman spectra and the results of spectral and statistical analyses of the SSTT are contained in the appendix.

Active imaging system performance model for target acquisition

NASA Astrophysics Data System (ADS)

Espinola, Richard L.; Teaney, Brian; Nguyen, Quang; Jacobs, Eddie L.; Halford, Carl E.; Tofsted, David H.

2007-04-01

The U.S. Army RDECOM CERDEC Night Vision & Electronic Sensors Directorate has developed a laser-range-gated imaging system performance model for the detection, recognition, and identification of vehicle targets. The model is based on the established US Army RDECOM CERDEC NVESD sensor performance models of the human system response through an imaging system. The Java-based model, called NVLRG, accounts for the effect of active illumination, atmospheric attenuation, and turbulence effects relevant to LRG imagers, such as speckle and scintillation, and for the critical sensor and display components. This model can be used to assess the performance of recently proposed active SWIR systems through various trade studies. This paper will describe the NVLRG model in detail, discuss the validation of recent model components, present initial trade study results, and outline plans to validate and calibrate the end-to-end model with field data through human perception testing.

Preliminary Experiments for the Assessment of V/W-band Links for Space-Earth Communications

NASA Technical Reports Server (NTRS)

Nessel, James A.; Acosta, Roberto J.; Miranda, Felix A.

2013-01-01

Since September 2012, NASA Glenn Research Center has deployed a microwave profiling radiometer at White Sands, NM, to estimate atmospheric propagation effects on communications links in the V and W bands (71-86GHz). Estimates of attenuation statistics in the millimeter wave due to gaseous and cloud components of the atmosphere show good agreement with current ITU-R models, but fail to predict link performance in the presence of moderate to heavy rain rates, due to the inherent limitations of passive radiometry. Herein, we discuss the preliminary results of these measurements and describe a design for a terrestrial link experiment to validate/refine existing rain attenuation models in the V/Wbands.

Double-Pulsed 2-Micrometer Lidar Validation for Atmospheric CO2 Measurements

NASA Technical Reports Server (NTRS)

Singh, Upendra N.; Refaat, Tamer F.; Yu, Jirong; Petros, Mulugeta; Remus, Ruben

2015-01-01

A double-pulsed, 2-micron Integrated Path Differential Absorption (IPDA) lidar instrument for atmospheric carbon dioxide (CO2) measurements is successfully developed at NASA Langley Research Center (LaRC). Based on direct detection technique, the instrument can be operated on ground or onboard a small aircraft. Key features of this compact, rugged and reliable IPDA lidar includes high transmitted laser energy, wavelength tuning, switching and locking, and sensitive detection. As a proof of concept, the IPDA ground and airborne CO2 measurement and validation will be presented. IPDA lidar CO2 measurements ground validation were conducted at NASA LaRC using hard targets and a calibrated in-situ sensor. Airborne validation, conducted onboard the NASA B-200 aircraft, included CO2 plum detection from power stations incinerators, comparison to in-flight CO2 in-situ sensor and comparison to air sampling at different altitude conducted by NOAA at the same site. Airborne measurements, spanning for 20 hours, were obtained from different target conditions. Ground targets included soil, vegetation, sand, snow and ocean. In addition, cloud slicing was examined over the ocean. These flight validations were conducted at different altitudes, up to 7 km, with different wavelength controlled weighing functions. CO2 measurement results agree with modeling conducted through the different sensors, as will be discussed.

Huygens/HASI 2002 balloon test campaign: Probe trajectory and atmospheric vertical profiles reconstruction

NASA Astrophysics Data System (ADS)

Gaborit, V.; Fulchignoni, M.; Colombatti, G.; Ferri, F.; Bettanini, C.

2004-08-01

In the framework of the activities going on in preparation for the mission of the Huygens probe in Titan's atmosphere (January 2005), the Huygens Atmospheric Structure Instrument (HASI) team scheduled and performed several balloon campaigns to test the HASI sensors' performance in flight conditions in the Earth's atmosphere. In particular, pressure conditions reached during each test are similar to those expected in Titan's lower atmosphere. A 1:1 scaled mock-up of the Huygens probe was launched with a stratospheric balloon in 2001 (Br. Assoc. Adv. Sci. 33 (2001) 1109) and in 2002 (Br. Assoc. Adv. Sci. 34 (2002) 911; Adv. Space. Sci. (2003)) from the G. Broglio base of the Italian Space Agency, located in Trapani Milo (Sicily). In both cases the mock-up was dropped from an altitude higher than 27 and 32 km, respectively, and recovered on the ground after a parachuted descent. In this paper, we describe the results obtained in reconstructing (i) the probe descent trajectory and (ii) the profiles of the physical quantities characterizing the Earth's atmosphere, on the basis of a complete analysis of the data obtained during the HASI 2002 balloon flight experiment. Using temperature and pressure measurements, we are able to reach an accuracy of the order of 0.5% on the altitude reconstruction during the descent. We validate both the models used for trajectory reconstruction and to check the sensors' performance. We describe the problems faced in determining the Huygens probe descent trajectory in Titan's atmosphere focusing our discussion on the critical aspects of the descent reconstruction (such as the uncertainties due to measurement errors, limited knowledge of the atmospheric composition, etc.) and the validity of the adopted assumptions.

Historical carbonyl sulfide observations support long-term growth in atmospheric CO2 seasonal amplitude

NASA Astrophysics Data System (ADS)

Campbell, J. E.; Hilton, T. W.; Laine, M.; Wang, Y.; Berry, J. A.; Hannigan, J. W.

2017-12-01

The seasonal amplitude in atmospheric CO2 has grown over the last 50 years, pointing to a fundamental shift in the regional carbon cycle. Theoretical drivers from the amplitude growth include changes in terrestrial photosynthesis and heterotrophic respiration. However, large-scale, measurement-based evidence for these mechanisms is unclear. Here we analyze historical measurements of carbonyl sulfide which also show long-term growth in seasonal amplitude. We use this new trend to interpret the underlying mechanisms of CO2 amplitude growth and to validate global ecosystem models.

SIERRA-Flux: Measuring Regional Surface Fluxes of Carbon Dioxide, Methane, and Water Vapor from an Unmanned Aircraft System

NASA Technical Reports Server (NTRS)

Fladeland; Yates, Emma Louise; Bui, Thaopaul Van; Dean-Day, Jonathan; Kolyer, Richard

2011-01-01

The Eddy-Covariance Method for quantifying surface-atmosphere fluxes is a foundational technique for measuring net ecosystem exchange and validating regional-to-global carbon cycle models. While towers or ships are the most frequent platform for measuring surface-atmosphere exchange, experiments using aircraft for flux measurements have yielded contributions to several large-scale studies including BOREAS, SMACEX, RECAB by providing local-to-regional coverage beyond towers. The low-altitude flight requirements make airborne flux measurements particularly dangerous and well suited for unmanned aircraft.

Gaseous Environment Considerations and Evaluation Programs Leading to Spacecraft Atmosphere Selection

NASA Technical Reports Server (NTRS)

Johnston, Richard S.; Michel, Edward L.; Smith, George B., Jr.

1965-01-01

The NASA Manned Spacecraft Center has been actively involved in the direction and support of programs leading to the selection and validations of the atmosphere for forthcoming Gemini and Apollo missions. This paper discusses the engineering and physiologic considerations involved, describes the investigations to validate spacecraft atmospheres, and discusses the implications derived from the results of these investigations.

Description of the University of Auckland Global Mars Mesoscale Meteorological Model (GM4)

NASA Astrophysics Data System (ADS)

Wing, D. R.; Austin, G. L.

2005-08-01

The University of Auckland Global Mars Mesoscale Meteorological Model (GM4) is a numerical weather prediction model of the Martian atmosphere that has been developed through the conversion of the Penn State University / National Center for Atmospheric Research fifth generation mesoscale model (MM5). The global aspect of this model is self consistent, overlapping, and forms a continuous domain around the entire planet, removing the need to provide boundary conditions other than at initialisation, yielding independence from the constraint of a Mars general circulation model. The brief overview of the model will be given, outlining the key physical processes and setup of the model. Comparison between data collected from Mars Pathfinder during its 1997 mission and simulated conditions using GM4 have been performed. Diurnal temperature variation as predicted by the model shows very good correspondence with the surface truth data, to within 5 K for the majority of the diurnal cycle. Mars Viking Data is also compared with the model, with good agreement. As a further means of validation for the model, various seasonal comparisons of surface and vertical atmospheric structure are conducted with the European Space Agency AOPP/LMD Mars Climate Database. Selected simulations over regions of interest will also be presented.

The Aggregate Representation of Terrestrial Land Covers Within Global Climate Models (GCM)

NASA Technical Reports Server (NTRS)

Shuttleworth, W. James; Sorooshian, Soroosh

1996-01-01

This project had four initial objectives: (1) to create a realistic coupled surface-atmosphere model to investigate the aggregate description of heterogeneous surfaces; (2) to develop a simple heuristic model of surface-atmosphere interactions; (3) using the above models, to test aggregation rules for a variety of realistic cover and meteorological conditions; and (4) to reconcile biosphere-atmosphere transfer scheme (BATS) land covers with those that can be recognized from space; Our progress in meeting these objectives can be summarized as follows. Objective 1: The first objective was achieved in the first year of the project by coupling the Biosphere-Atmosphere Transfer Scheme (BATS) with a proven two-dimensional model of the atmospheric boundary layer. The resulting model, BATS-ABL, is described in detail in a Masters thesis and reported in a paper in the Journal of Hydrology Objective 2: The potential value of the heuristic model was re-evaluated early in the project and a decision was made to focus subsequent research around modeling studies with the BATS-ABL model. The value of using such coupled surface-atmosphere models in this research area was further confirmed by the success of the Tucson Aggregation Workshop. Objective 3: There was excellent progress in using the BATS-ABL model to test aggregation rules for a variety of realistic covers. The foci of attention have been the site of the First International Satellite Land Surface Climatology Project Field Experiment (FIFE) in Kansas and one of the study sites of the Anglo-Brazilian Amazonian Climate Observational Study (ABRACOS) near the city of Manaus, Amazonas, Brazil. These two sites were selected because of the ready availability of relevant field data to validate and initiate the BATS-ABL model. The results of these tests are given in a Masters thesis, and reported in two papers. Objective 4: Progress far exceeded original expectations not only in reconciling BATS land covers with those that can be recognized from space, but also in then applying remotely-sensed land cover data to map aggregate values of BATS parameters for heterogeneous covers and interpreting these parameters in terms of surface-atmosphere exchanges.

Comparison of model predictions for the composition of the ionosphere of Mars to MAVEN NGIMS data

NASA Astrophysics Data System (ADS)

Withers, Paul; Vogt, Marissa; Mayyasi, Majd; Mahaffy, Paul; Benna, Mehdi; Elrod, Meredith; Bougher, Stephen; Dong, Chuanfei; Chaufray, Jean-Yves; Ma, Yingjuan; Jakosky, Bruce

2015-11-01

Prior to the arrival of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft at Mars, the only available measurements of the composition of the planet's ionosphere were those acquired by the two Viking Landers during their atmospheric entries. Many numerical models of the composition of the ionosphere of Mars have been developed, but these have only been validated for species, altitudes, and conditions for which Viking data exist. Here we compare the ionospheric composition and structure predicted by 10 ionospheric models at solar zenith angles of 45-60° against ion density measurements acquired by the MAVEN Neutral Gas and Ion Mass Spectrometer (NGIMS). The most successful models included three-dimensional plasma transport driven by interactions with the surrounding space environment but had relatively simple ionospheric chemistry.

Gridded emission inventory of short-chain chlorinated paraffins and its validation in China.

PubMed

Jiang, Wanyanhan; Huang, Tao; Mao, Xiaoxuan; Wang, Li; Zhao, Yuan; Jia, Chenhui; Wang, Yanan; Gao, Hong; Ma, Jianmin

2017-01-01

China produces approximately 20%-30% of the total global chlorinated paraffins (CPs). The establishment of a short-chain CP (SCCP) emission inventory is a significant step toward risk assessment and regulation of SCCPs in China and throughout the globe. This study developed a gridded SCCPs emission inventory with a 1/4° longitude by 1/4° latitude resolution from 2008 to 2012 for China, which was based on the total annual CPs emissions for the nation. The total national SCCPs emission during this 5-year period was 5651.5 tons. An additive in metal cutting fluids was a major emission source in China, contributing 2680.2 tons to the total atmospheric emissions of SCCPs from 2008 to 2012, followed by the production of CPs (2281.8 tons), plasticizers (514.3 tons), flame retardants (108.6 tons), and net import (66.6 tons). Most of these emission sources are located along the eastern seaboard of China and southern China. A coupled atmospheric transport model was employed to simulate environmental contamination by SCCPs using the gridded emission inventory of SCCPs from 2008 to 2012 as the model initial conditions. Simulated atmospheric and soil concentrations were compared with field monitoring data to validate the emission inventory. The results showed good consistency between modeled and field sampling data, supporting the reliability and credibility of the gridded SCCPs emission inventory that was developed in the present study. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advection of Potential Temperature in the Atmosphere of Irradiated Exoplanets: A Robust Mechanism to Explain Radius Inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tremblin, P.; Chabrier, G.; Mayne, N. J.

The anomalously large radii of strongly irradiated exoplanets have remained a major puzzle in astronomy. Based on a two-dimensional steady-state atmospheric circulation model, the validity of which is assessed by comparison to three-dimensional calculations, we reveal a new mechanism, namely the advection of the potential temperature due to mass and longitudinal momentum conservation, a process occurring in the Earth’s atmosphere or oceans. In the deep atmosphere, the vanishing heating flux forces the atmospheric structure to converge to a hotter adiabat than the one obtained with 1D calculations, implying a larger radius for the planet. Not only do the calculations reproducemore » the observed radius of HD 209458b, but also reproduce the observed correlation between radius inflation and irradiation for transiting planets. Vertical advection of potential temperature induced by non-uniform atmospheric heating thus provides a robust mechanism to explain the inflated radii of irradiated hot Jupiters.« less

A global validation of ERA-Interim integrated water vapor estimates using ground-based GNSS observations

NASA Astrophysics Data System (ADS)

Ahmed, F.; Dousa, J.; Hunegnaw, A.; Teferle, F. N.; Bingley, R.

2017-12-01

Integrated water vapor (IWV) derived from climate reanalysis models, such as the European Centre for Medium-range Weather Forecasts (ECMWF) ReAnalysis-Interim (ERA-Interim), is widely used in many atmospheric applications. Therefore, it is of interest to assess the quality of this reanalysis product using available observations. Observations from Global Navigation Satellite Systems (GNSS) are, as of now, available for a period of over 2 decades and their global availability makes it possible to validate the IWV obtained from climate reanalysis models in different geographical and climatic regions. In this study, primarily, three 5-year long homogeneously reprocessed GNSS-derived IWV datasets containing over 400 globally distributed ground-based GNSS stations have been used to validate the IWV estimates obtained from the ERA-Interim climate reanalysis model in 25 different climate zones. The IWV from ERA-Interim has been obtained by vertically integrating the specific humidity at all model levels above the locations of GNSS stations. It has been studied how the difference between the ERA-Interim IWV and the GNSS-derived IWV varies with respect to the different climate zones as well as with respect to the difference in the model orography and latitude. The results show a dependence of the ability of ERA-Interim to model the IWV on difference in climate types and latitude. This dependence, however, is dictated by the concentration of water vapor in different climate zones and at different latitudes. Furthermore, as a secondary focus of this study, the weighted mean atmospheric temperature (Tm) obtained from ERA-Interim has been compared to its equivalent obtained using two widely used approximations globally.

Solar UV Radiation and the Origin of Life on Earth

NASA Technical Reports Server (NTRS)

Heap, S. R.; Gaidos, E.; Hubeny, I.; Lanz, T. M.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield, and energy source for life. Here, we give a progress report on the first phase of this program: to establish the UV radiation from the early Sun. We are presently obtaining ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun. We are currently making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. once validated, these models will allow us to extrapolate our theoretical spectra to unobserved spectral regions, and to proceed to the next step: to develop photochemical models of the pre-biotic and Archean atmosphere of the Earth.

Expressions for the spherical-wave-structure function based on a bump spectrum model for the index of refraction

NASA Astrophysics Data System (ADS)

Richardson, Christina E.; Andrews, Larry C.

1991-07-01

New spectra models have recently been developed for the spatial power spectra of temperature and refractive index fluctuations in the atmospheric boundary layer showing the characteristic 'bump' just prior to the dissipation ranges. Theoretical work involving these new models has led to new expressions for the phase structure function associated with a plane optical wave, although most experimental work has involved spherical waves. Following techniques similar to those used for the plane wave analysis, new expressions valid in geometrical and diffraction regimes are developed here for the phase structure function of a spherical optical wave propagating through clear-air atmospheric turbulence. Useful asymptotic formulas for small separation distances and the inertial subrange are derived from these general expressions.

A Low Mach Number Model for Moist Atmospheric Flows

DOE PAGES

Duarte, Max; Almgren, Ann S.; Bell, John B.

2015-04-01

A low Mach number model for moist atmospheric flows is introduced that accurately incorporates reversible moist processes in flows whose features of interest occur on advective rather than acoustic time scales. Total water is used as a prognostic variable, so that water vapor and liquid water are diagnostically recovered as needed from an exact Clausius–Clapeyron formula for moist thermodynamics. Low Mach number models can be computationally more efficient than a fully compressible model, but the low Mach number formulation introduces additional mathematical and computational complexity because of the divergence constraint imposed on the velocity field. Here in this paper, latentmore » heat release is accounted for in the source term of the constraint by estimating the rate of phase change based on the time variation of saturated water vapor subject to the thermodynamic equilibrium constraint. Finally, the authors numerically assess the validity of the low Mach number approximation for moist atmospheric flows by contrasting the low Mach number solution to reference solutions computed with a fully compressible formulation for a variety of test problems.« less

A Low Mach Number Model for Moist Atmospheric Flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duarte, Max; Almgren, Ann S.; Bell, John B.

A low Mach number model for moist atmospheric flows is introduced that accurately incorporates reversible moist processes in flows whose features of interest occur on advective rather than acoustic time scales. Total water is used as a prognostic variable, so that water vapor and liquid water are diagnostically recovered as needed from an exact Clausius–Clapeyron formula for moist thermodynamics. Low Mach number models can be computationally more efficient than a fully compressible model, but the low Mach number formulation introduces additional mathematical and computational complexity because of the divergence constraint imposed on the velocity field. Here in this paper, latentmore » heat release is accounted for in the source term of the constraint by estimating the rate of phase change based on the time variation of saturated water vapor subject to the thermodynamic equilibrium constraint. Finally, the authors numerically assess the validity of the low Mach number approximation for moist atmospheric flows by contrasting the low Mach number solution to reference solutions computed with a fully compressible formulation for a variety of test problems.« less

Venus Global Reference Atmospheric Model Status and Planned Updates

NASA Technical Reports Server (NTRS)

Justh, H. L.; Dwyer Cianciolo, A. M.

2017-01-01

The Venus Global Reference Atmospheric Model (Venus-GRAM) was originally developed in 2004 under funding from NASA's In Space Propulsion (ISP) Aerocapture Project to support mission studies at the planet. Many proposals, including NASA New Frontiers and Discovery, as well as other studies have used Venus-GRAM to design missions and assess system robustness. After Venus-GRAM's release in 2005, several missions to Venus have generated a wealth of additional atmospheric data, yet few model updates have been made to Venus-GRAM. This paper serves to address three areas: (1) to present the current status of Venus-GRAM, (2) to identify new sources of data and other upgrades that need to be incorporated to maintain Venus-GRAM credibility and (3) to identify additional Venus-GRAM options and features that could be included to increase its capability. This effort will de-pend on understanding the needs of the user community, obtaining new modeling data and establishing a dedicated funding source to support continual up-grades. This paper is intended to initiate discussion that can result in an upgraded and validated Venus-GRAM being available to future studies and NASA proposals.

Regional climates in the GISS global circulation model - Synoptic-scale circulation

NASA Technical Reports Server (NTRS)

Hewitson, B.; Crane, R. G.

1992-01-01

A major weakness of current general circulation models (GCMs) is their perceived inability to predict reliably the regional consequences of a global-scale change, and it is these regional-scale predictions that are necessary for studies of human-environmental response. For large areas of the extratropics, the local climate is controlled by the synoptic-scale atmospheric circulation, and it is the purpose of this paper to evaluate the synoptic-scale circulation of the Goddard Institute for Space Studies (GISS) GCM. A methodology for validating the daily synoptic circulation using Principal Component Analysis is described, and the methodology is then applied to the GCM simulation of sea level pressure over the continental United States (excluding Alaska). The analysis demonstrates that the GISS 4 x 5 deg GCM Model II effectively simulates the synoptic-scale atmospheric circulation over the United States. The modes of variance describing the atmospheric circulation of the model are comparable to those found in the observed data, and these modes explain similar amounts of variance in their respective datasets. The temporal behavior of these circulation modes in the synoptic time frame are also comparable.

A New Similarity theory for Strongly Unstable Atmospheric Surface Layer

NASA Astrophysics Data System (ADS)

Ji, Yong; She, Zhen-Su

2017-11-01

We apply the structural ensemble dynamics (SED) theory to analyze mean velocity and streamwise turbulence intensity distribution in unstable atmospheric surface layer (ASL). The turbulent kinetic energy balance equation in ASL asserts that above a critical height zL, the buoyancy production cannot be neglected. The SED theory predicts that a stress length function displays a generalized scaling law from z to z 4 / 3. The zL derived from observational data show a two-regime form with Obukhov length L , including a linear dependence for moderate heat flux and a constant regime for large heat flux, extending the Monin-Obukhov similarity theory which is only valid for large | L | . This two-regime description is further extended to model turbulent intensity, with a new similarity coordinate Lz such that the observational data collapse for all L. Finally, we propose a phase diagram for characterizing different ASL flow regimes, and the corresponding flow structures are discussed. In summary, a new similarity theory for unstable atmosphere is constructed, and validated by observational data of the mean velocity and streamwise turbulence intensity distribution for all heat flux regimes.

Performance analysis of the lineal model for estimating the maximum power of a HCPV module in different climate conditions

NASA Astrophysics Data System (ADS)

Fernández, Eduardo F.; Almonacid, Florencia; Sarmah, Nabin; Mallick, Tapas; Sanchez, Iñigo; Cuadra, Juan M.; Soria-Moya, Alberto; Pérez-Higueras, Pedro

2014-09-01

A model based on easily obtained atmospheric parameters and on a simple lineal mathematical expression has been developed at the Centre of Advanced Studies in Energy and Environment in southern Spain. The model predicts the maximum power of a HCPV module as a function of direct normal irradiance, air temperature and air mass. Presently, the proposed model has only been validated in southern Spain and its performance in locations with different atmospheric conditions still remains unknown. In order to address this issue, several HCPV modules have been measured in two different locations with different climate conditions than the south of Spain: the Environment and Sustainability Institute in southern UK and the National Renewable Energy Center in northern Spain. Results show that the model has an adequate match between actual and estimated data with a RMSE lower than 3.9% at locations with different climate conditions.

The Madden-Julian Oscillation and its Impact on Northern Hemisphere Weather Predictability during Wintertime

NASA Technical Reports Server (NTRS)

Jones, Charles; Waliser, Duane E.; Lau, K. M.; Stern, W.

2003-01-01

The Madden-Julian Oscillation (MJO) is known as the dominant mode of tropical intraseasonal variability and has an important role in the coupled-atmosphere system. This study used twin numerical model experiments to investigate the influence of the MJO activity on weather predictability in the midlatitudes of the Northern Hemisphere during boreal winter. The National Aeronautics and Space Administration (NASA) Goddard laboratory for the Atmospheres (GLA) general circulation model was first used in a 10-yr simulation with fixed climatological SSTs to generate a validation data set as well as to select initial conditions for active MJO periods and Null cases. Two perturbation numerical experiments were performed for the 75 cases selected [(4 MJO phases + Null phase) _ 15 initial conditions in each]. For each alternative initial condition, the model was integrated for 90 days. Mean anomaly correlations in the midlatitudes of the Northern Hemisphere (2O deg N_60 deg.N) and standardized root-mean-square errors were computed to validate forecasts and control run. The analyses of 500-hPa geopotential height, 200-hPa Streamfunction and 850-hPa zonal wind component systematically show larger predictability during periods of active MJO as opposed to quiescent episodes of the oscillation.

Sensitivity of erythemal UV/global irradiance ratios to atmospheric parameters: application for estimating erythemal radiation at four sites in Thailand

NASA Astrophysics Data System (ADS)

Buntoung, Sumaman; Janjai, Serm; Nunez, Manuel; Choosri, Pranomkorn; Pratummasoot, Noppamas; Chiwpreecha, Kulanist

2014-11-01

Factors affecting the ratio of erythemal UV (UVER) to broadband (G) irradiance were investigated in this study. Data from four solar monitoring sites in Thailand, namely Chiang Mai, Ubon Ratchathani, Nakhon Pathom and Songkhla were used to investigate the UVER/G ratio in response to geometric and atmospheric parameters. These comprised solar zenith angle, aerosol load, total ozone column, precipitable water and clearness index. A modeling scheme was developed to isolate and examine the effect of each individual environmental parameter on the ratio. Results showed that all parameters with the exception of solar zenith angle and clearness index influenced the ratios in a linear manner. These results were also used to develop a semi-empirical model for estimating hourly erythemal UV irradiance. Data from 2009 to 2010 were used to construct the ratio model while validation was performed using erythemal UV irradiance at the above four sites in 2011. The validation results showed reasonable agreement with a root mean square difference of 13.5% and mean bias difference of - 0.5%, under all sky conditions and 10.9% and - 0.3%, respectively, under cloudless conditions.

The extended Fourier pseudospectral time-domain method for atmospheric sound propagation.

PubMed

Hornikx, Maarten; Waxler, Roger; Forssén, Jens

2010-10-01

An extended Fourier pseudospectral time-domain (PSTD) method is presented to model atmospheric sound propagation by solving the linearized Euler equations. In this method, evaluation of spatial derivatives is based on an eigenfunction expansion. Evaluation on a spatial grid requires only two spatial points per wavelength. Time iteration is done using a low-storage optimized six-stage Runge-Kutta method. This method is applied to two-dimensional non-moving media models, one with screens and one for an urban canyon, with generally high accuracy in both amplitude and phase. For a moving atmosphere, accurate results have been obtained in models with both a uniform and a logarithmic wind velocity profile over a rigid ground surface and in the presence of a screen. The method has also been validated for three-dimensional sound propagation over a screen. For that application, the developed method is in the order of 100 times faster than the second-order-accurate FDTD solution to the linearized Euler equations. The method is found to be well suited for atmospheric sound propagation simulations where effects of complex meteorology and straight rigid boundary surfaces are to be investigated.

Monitoring Orbital Precession of EO-1 Hyperion with Three Atmospheric Correction Models in the Libya-4 PICS

NASA Technical Reports Server (NTRS)

Neigh, Christopher; McCorkel, Joel; Campbell, Petya; Ong, Laurence; Ly, Vuong; Landis, David; Fry, Stuart; Middleton, Elizabeth

2016-01-01

Spaceborne spectrometers require spectral-temporal stability characterization to aid validation of derived data products. EO-1 began orbital precession in 2011 after exhausting onboard fuel resources. In the Libya-4 Pseudo Invariant Calibration Site (PICS) this resulted in a progressive shift from a mean local equatorial crossing time of approx. 10:00 AM in 2011 to approx. 8:30 AM in late 2015. Here, we studied precession impacts to Hyperion surface reflectance products using three atmospheric correction approaches from 2004 to 2015. Combined difference estimates of surface reflectance were < 5% in the visible near infrared (VNIR) and < 10% for most of the shortwave infrared (SWIR). Combined coefficient of variation (CV) estimates in the VNIR ranged from 0.025 ? 0.095, and in the SWIR ranged from 0.025 ? 0.06, excluding bands near atmospheric absorption features. Reflectances produced with different atmospheric models were correlated (R2) in VNIR from 0.25 ? 0.94 and SWIR from 0.12 ? 0.88 (p < 0.01). The uncertainties in all models increased with terrain slope up to 15deg and selecting dune flats could reduce errors. We conclude that these data remain a useful resource over this period.

Martian atmospheric gravity waves simulated by a high-resolution general circulation model

NASA Astrophysics Data System (ADS)

Kuroda, Takeshi; Yiǧit, Erdal; Medvedev, Alexander S.; Hartogh, Paul

2016-07-01

Gravity waves (GWs) significantly affect temperature and wind fields in the Martian middle and upper atmosphere. They are also one of the observational targets of the MAVEN mission. We report on the first simulations with a high-resolution general circulation model (GCM) and present a global distributions of small-scale GWs in the Martian atmosphere. The simulated GW-induced temperature variances are in a good agreement with available radio occultation data in the lower atmosphere between 10 and 30 km. For the northern winter solstice, the model reveals a latitudinal asymmetry with stronger wave generation in the winter hemisphere and two distinctive sources of GWs: mountainous regions and the meandering winter polar jet. Orographic GWs are filtered upon propagating upward, and the mesosphere is primarily dominated by harmonics with faster horizontal phase velocities. Wave fluxes are directed mainly against the local wind. GW dissipation in the upper mesosphere generates a body force per unit mass of tens of m s^{-1} per Martian solar day (sol^{-1}), which tends to close the simulated jets. The results represent a realistic surrogate for missing observations, which can be used for constraining GW parameterizations and validating GCMs.

A comparative study of various inflow boundary conditions and turbulence models for wind turbine wake predictions

NASA Astrophysics Data System (ADS)

Tian, Lin-Lin; Zhao, Ning; Song, Yi-Lei; Zhu, Chun-Ling

2018-05-01

This work is devoted to perform systematic sensitivity analysis of different turbulence models and various inflow boundary conditions in predicting the wake flow behind a horizontal axis wind turbine represented by an actuator disc (AD). The tested turbulence models are the standard k-𝜀 model and the Reynolds Stress Model (RSM). A single wind turbine immersed in both uniform flows and in modeled atmospheric boundary layer (ABL) flows is studied. Simulation results are validated against the field experimental data in terms of wake velocity and turbulence intensity.

An attempt for modeling the atmospheric transport of 3H around Kakrapar Atomic Power Station.

PubMed

Patra, A K; Nankar, D P; Joshi, C P; Venkataraman, S; Sundar, D; Hegde, A G

2008-01-01

Prediction of downwind tritium air concentrations in the environment around Kakrapar Atomic Power Station (KAPS) was studied on the basis of Gaussian plume dispersion model. The tritium air concentration by field measurement [measured tritium air concentrations in the areas adjacent to KAPS] were compared with the theoretically calculated values (predicted) to validate the model. This approach will be useful in evaluating environmental radiological impacts due to pressurised heavy water reactors.

Remote Sensing and Imaging Physics

DTIC Science & Technology

2012-03-07

Model Analysis Process Wire-frame Shape Model a s s u m e d a p rio ri k n o w le d g e No material BRDF library employed in retrieval...a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 07 MAR 2012 2. REPORT TYPE 3. DATES COVERED...imaging estimation problems Allows properties of local maxima to be derived from the Kolmogorov model of atmospheric turbulence: Each speckle

LiveOcean: A Daily Forecast Model of Ocean Acidification for Shellfish Growers

NASA Astrophysics Data System (ADS)

MacCready, P.; Siedlecki, S. A.; McCabe, R. M.

2016-12-01

The coastal estuaries of the NE Pacific host a highly productive shellfish industry, but in the past decade they have suffered from many years in which no natural set of oysters occurred. It appears that coastal waters with low Aragonite saturation state may be the cause. This "acidified" water is the result of (i) upwelling of NE Pacific water from near the shelf break that is already low in pH, and (ii) further acidification of that water by productivity and remineralization on the shelf, and (iii) increasing atmospheric CO2. As part of a coordinated research response to this issue, we have developed the LiveOcean modeling system, which creates daily three-day forecasts of circulation and biogeochemical properties in Oregon-Washington-British Columbia coastal and estuarine waters. The system includes realistic tides, atmospheric forcing (from a regional WRF model), ocean boundary conditions (from HYCOM), and rivers (from USGS and Environment Canada). The model is also used for Harmful Algal Bloom prediction. There has been extensive validation of hindcast runs for currents and hydrography, and more limited validation of biogeochemical variables. Model results are pushed daily to the cloud, and made available to the public through the NANOOS Visualization System (NVS). NVS also includes automated model-data comparisons with real-time NDBC and OOI moorings. Future work will focus on optimizing the utility of this system for regional shellfish growers.

Retrieval with Infrared Atmospheric Sounding Interferometer and Validation during JAIVEx

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schluessel, Peter; Strow, L. Larrabee; Mango, Stephen A.

2008-01-01

A state-of-the-art IR-only retrieval algorithm has been developed with an all-season-global EOF Physical Regression and followed by 1-D Var. Physical Iterative Retrieval for IASI, AIRS, and NAST-I. The benefits of this retrieval are to produce atmospheric structure with a single FOV horizontal resolution (approx. 15 km for IASI and AIRS), accurate profiles above the cloud (at least) or down to the surface, surface parameters, and/or cloud microphysical parameters. Initial case study and validation indicates that surface, cloud, and atmospheric structure (include TBL) are well captured by IASI and AIRS measurements. Coincident dropsondes during the IASI and AIRS overpasses are used to validate atmospheric conditions, and accurate retrievals are obtained with an expected vertical resolution. JAIVEx has provided the data needed to validate the retrieval algorithm and its products which allows us to assess the instrument ability and/or performance. Retrievals with global coverage are under investigation for detailed retrieval assessment. It is greatly desired that these products be used for testing the impact on Atmospheric Data Assimilation and/or Numerical Weather Prediction.

MUSICA MetOp/IASI {H2O,δD} pair retrieval simulations for validating tropospheric moisture pathways in atmospheric models

NASA Astrophysics Data System (ADS)

Schneider, Matthias; Borger, Christian; Wiegele, Andreas; Hase, Frank; García, Omaira E.; Sepúlveda, Eliezer; Werner, Martin

2017-02-01

The project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) has shown that the sensor IASI aboard the satellite MetOp can measure the free tropospheric {H2O,δD} pair distribution twice per day on a quasi-global scale. Such data are very promising for investigating tropospheric moisture pathways, however, the complex data characteristics compromise their usage in the context of model evaluation studies. Here we present a tool that allows for simulating MUSICA MetOp/IASI {H2O,δD} pair remote sensing data for a given model atmosphere, thereby creating model data that have the remote sensing data characteristics assimilated. This model data can then be compared to the MUSICA data. The retrieval simulation method is based on the physical principles of radiative transfer and we show that the uncertainty of the simulations is within the uncertainty of the MUSICA MetOp/IASI products, i.e. the retrieval simulations are reliable enough. We demonstrate the working principle of the simulator by applying it to ECHAM5-wiso model data. The few case studies clearly reveal the large potential of the MUSICA MetOp/IASI {H2O,δD} data pairs for evaluating modelled moisture pathways. The tool is made freely available in form of MATLAB and Python routines and can be easily connected to any atmospheric water vapour isotopologue model.

Late paleozoic fusulinoidean gigantism driven by atmospheric hyperoxia.

PubMed

Payne, Jonathan L; Groves, John R; Jost, Adam B; Nguyen, Thienan; Moffitt, Sarah E; Hill, Tessa M; Skotheim, Jan M

2012-09-01

Atmospheric hyperoxia, with pO(2) in excess of 30%, has long been hypothesized to account for late Paleozoic (360-250 million years ago) gigantism in numerous higher taxa. However, this hypothesis has not been evaluated statistically because comprehensive size data have not been compiled previously at sufficient temporal resolution to permit quantitative analysis. In this study, we test the hyperoxia-gigantism hypothesis by examining the fossil record of fusulinoidean foraminifers, a dramatic example of protistan gigantism with some individuals exceeding 10 cm in length and exceeding their relatives by six orders of magnitude in biovolume. We assembled and examined comprehensive regional and global, species-level datasets containing 270 and 1823 species, respectively. A statistical model of size evolution forced by atmospheric pO(2) is conclusively favored over alternative models based on random walks or a constant tendency toward size increase. Moreover, the ratios of volume to surface area in the largest fusulinoideans are consistent in magnitude and trend with a mathematical model based on oxygen transport limitation. We further validate the hyperoxia-gigantism model through an examination of modern foraminiferal species living along a measured gradient in oxygen concentration. These findings provide the first quantitative confirmation of a direct connection between Paleozoic gigantism and atmospheric hyperoxia. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Quantifying the Uncertainty in Estimates of Surface Atmosphere Fluxes by Evaluation of SEBS and SCOPE Models

NASA Astrophysics Data System (ADS)

Timmermans, J.; van der Tol, C.; Verhoef, A.; Wang, L.; van Helvoirt, M.; Verhoef, W.; Su, Z.

2009-11-01

An earth observation based evapotranspiration (ET) product is essential to achieving the GEWEX CEOP science objectives and to achieve the GEOSS water resources societal benefit areas. Conventional techniques that employ point measurements to estimate the components of the energy balance are only representative for local scales and cannot be extended to large areas because of the heterogeneity of the land surface and the dynamic nature of heat transfer processes.The objective of this research is to quantify the uncertainties of evapotranspiration estimates by the Surface Energy Balance System (SEBS) algorithm through validation against the detailed Soil Canopy Observation, Photochemistry and Energy fluxes process (SCOPE) model with site optimized parameters. This SCOPE model takes both radiative processes and biochemical processes into account; it combines the SAIL radiative transfer model with the energy balance at leaf level to simulate the interaction between surface and atmosphere. In this paper the validation results are presented for a semi long term dataset in Reading on 2002.The comparison between the two models showed a high correlation over the complete growth of maize capturing the daily variation to good extent. The absolute values of the SEBS model are however much lower compared to those of the SCOPE model. This is due to the fact the SEBS model uses a surface resistance parameterization that is unable to account of high vegetation. An update of the SEBS model will resolve this problem.

Demonstrating the Importance of `` Good" Models of Land Surface Hydrological Processes

NASA Astrophysics Data System (ADS)

Pitman, A.; Irannejad, P.; McGuffie, K.; Henderson-Sellers, A.

2003-12-01

To reduce the uncertainty in the prediction of land surface climates,, the Atmospheric Model Intercomparison Project (AMIP) Diagnostic Subproject 12 (DSP 12) and the Project for Intercomparison of Land-surface Parameterisation Schemes (PILPS) have analysed dependence of climate simulations on the land-surface schemes (LSSs). This analysis has comprised three efforts: (i) proving that LSSs matter in coupled simulations; (ii) investigating whether improvements in LSSs have occurred over time; and (iii) searching for novel means of validating LSS predictions. In the first, Irannejad et al. (2003) introduce a novel method for evaluating the dependence of 19 AMIP AGCMs' LH on the LSS by excluding the impact of the atmosphere. Pseudo LSSs (PLSSs) for LH in the form of multi-variable linear models expressing mean monthly LH as a function of atmospheric forcing are developed. Analysis over three large and climatically diverse river basins shows estimates of mean annual LH from the PLSSs agreeing well with the AGCMs' simulations. RMS errors range from 0.4 to 2.2 W m-2 depending on the region and the AGCM. When the PLSSs are driven by single atmospheric forcings, different LSSs behave differently, and the variability of mean annual LH among AGCMs increases. The second strand of our investigation uncovered a clear generational sequence of land-surface schemes: first generation 'no canopy'; second generation ` SiBlings'; and ` recent schemes'. We conclude that although continental surface modelling has improved over the last 30 years, full confidence remains elusive, in part due to tuning to available observations. Finally, we show that stable water isotopes challenge predictions of evaporation and condensation processes. These three-pronged findings prove that LSSs are important to AGCM and coupled climate predictions; demonstrate that new, or changed, land-surface components increase diversity among simulations; underline the need for validation data and also challenge current parameterisations with novel observations.

Setting up infrasonic propagation simulation using the latest real-time atmospheric specifications at the IDC

NASA Astrophysics Data System (ADS)

Brachet, N.; Mialle, P.; Brown, D.; Coyne, J.; Drob, D.; Virieux, J.; Garcés, M.

2009-04-01

The International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty (CTBTO) Preparatory Commission in Vienna is pursuing its automatic processing effort for the return of infrasound data processing into operations in 2009. Concurrently, work is also underway to further improve this process by enhancing the modeling of the infrasound propagation in the atmosphere and then by labeling the phases in order to improve the event categorization and location. In 2008, the IDC acquired WASP-3D Sph (Windy Atmospheric Sonic Propagation) (Virieux et al., 2004) a 3-D ray-tracing based long range propagation software that accounts for the heterogeneity of the atmosphere. Once adapted to the IDC environment, WASP-3 Sph has been used to improve the understanding of infrasound wave propagation and has been compared with the 1-D ray tracing Taupc software (Garcés and Drob, 2007) at the IDC. In addition to performing the infrasound propagation simulation, different atmospheric models are available at the IDC, either real-time: ECMWF (European Centre for Middle-range Weather Forecast), or empiric: HWM93 (Horizontal Wind Model) and HWM07 (Drob, 2008), used in their initial format or interpolated into G2S (Ground to Space) model. The IDC infrasound reference database is used for testing, comparing and validating the various propagation software and atmospheric specifications. Moreover all the performed simulations are giving feedback on the quality of the infrasound reference events and provide useful information to improve their location by refining infrasonic wave propagation characteristics. The results of this study are presented for a selection of reference events and they will help the IDC designing and defining short and mid-term enhancements of the infrasound automatic and interactive processing to take into account the spatial and temporal heterogeneities of the atmosphere.

Philippines TCCON Project: Installation, Operation, and Comparisons with GOSAT and OCO-2 Data

NASA Astrophysics Data System (ADS)

Morino, I.; Velazco, V. A.; Hori, A.; Uchino, O.; Sakai, T.; Izumi, T.; Nagai, T.; Bagtasa, G.; Yoshida, Y.; Kiel, M.; Bukosa, B.; Deutscher, N. M.; Fisher, J. A.; Griffith, D. W. T.

2017-12-01

TCCON is dedicated to the precise measurements of greenhouse gases (GHGs) such as CO2 and CH4. TCCON measurements have been and are currently used extensively and globally for satellite validation, for comparison with atmospheric chemistry models and to study atmosphere-biosphere exchanges of carbon. With the global effort to cap GHG emissions, TCCON has taken on a vital role in validating satellite-based GHG data from past, current and future missions like Japanese GOSAT and GOSAT-2, NASA's OCO-2 and OCO-3, Chinese TanSat, TROPOMI, and others. The lack of reliable validation data for the satellite-based GHG observing missions in the tropical regions is a common limitation in global carbon-cycle modeling studies that have a tropical component. The international CO2 modeling community has specified a requirement for "expansion of the CO2 observation network within the tropics" to reduce uncertainties in regional estimates of CO2sources and sinks using atmospheric transport models. To address this challenge, we installed a newly-constructed TCCON FTS at a wind farm operated by the Energy Development Corporation in Burgos, Ilocos Norte, Philippines (18.5326° N, 120.6496° E), which followed rigorous site assessments and discussions at several TCCON and GOSAT-2 science team meetings. After developing the TCCON instrument and characterizing its performance at the NIES in Japan, we deployed the TCCON FTS at the Burgos site in Dec. 2016. Installation and set up of the instruments were concluded in Mar. 2017, followed by first measurements of solar absorption spectra and continued operations in the Philippines using TCCON protocols. Here, we will show obvious CO2, CH4and CO enhancements were observed in Mar. 2017, accompanied by clear depolarization signals from a LIDAR instrument. These enhancements are probably caused by outflow of pollution from major cities in China but the emissions are underestimated in the GEOS-Chem model. Comparisons with GOSAT and OCO-2 soundings will also be shown. The Burgos site has been approved as an official TCCON site with a provisional status at the last TCCON meeting in Jun. 2017.

Validation of Mars-GRAM and Planned New Features

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2004-01-01

For altitudes below 80 km, Mars Global Reference Atmospheric Model (Mars-GRAM 2001) is based on output climatology from NASA Ames Mars General Circulation Model (MGCM). At COSPAR 2002, results were presented of validation tests of Mars-GRAM versus data from Mars Global Surveyor Thermal Emission Spectrometer (TES) and Radio Science (RS) experiment. Further validation tests are presented comparing Mars- GRAM densities with those from the European Mars Climate Database (MCD), and comparing densities from both Mars-GRAM and MCD against TES observations. Throughout most of the height and latitude range of TES data (040 km and 70s to 70N), good agreement is found between atmospheric densities from Mars-GRAM and MCD. However, at the season and latitude zone for Mars Phoenix arrival and landing (Ls = 65 to 80 degrees and latitude 65 to 75N), Mars-GRAM densities are about 30 to 45 percent higher than MCD densities near 40 km altitude. Further evaluation is warranted concerning potential impact of these model differences on planning for Phoenix entry and descent. Three planned features for Mars-GRAM update are also discussed: (1) new MGCM and Thermospheric General Circulation Model data sets to be used as a revised basis for Mars-GRAM mean atmosphere, (2) a new feature to represent planetary-scale traveling waves for upper altitude density variations (such as found during Mars Odyssey aerobraking), and (3) a new model for effects of high resolution topographic slope on winds near the surface (0 to 4.5 km above MOLA topography level). Mars-GRAM slope winds will be computed from a diagnostic (algebraic) relationship based on Ye, Segal, and Pielke (1990). This approach differs from mesoscale models (such as MRAMS and Mars MM5), which use prognostic, full-physics solutions of the time- and space-dependent differential equations of motion. As such, slope winds in Mars-GRAM will be consistent with its "engineering-level" approach, and will be extremely fast and easy to evaluate, compared with mesoscale model solutions. Mars-GRAM slope winds are not being suggested as a replacement for sophisticated, full-physics Mars mesoscale models, but may have value, particularly for preliminary screening of large numbers of candidate landing sites for future Mars missions, such as Phoenix and Mars Science Laboratory. Test output is presented from Mars-GRAM slope winds in the area of Gusev Crater and Valles Marineris.

GOCE: The first seismometer in orbit around the Earth

NASA Astrophysics Data System (ADS)

Garcia, Raphael F.; Bruinsma, Sean; Lognonné, Philippe; Doornbos, Eelco; Cachoux, Florian

2013-03-01

The first in situ sounding of a post-seismic infrasound wavefront is presented, using data from the GOCE mission. The atmospheric infrasounds following the great Tohoku earthquake (on 11 March 2011) induce variations of air density and vertical acceleration of the GOCE platform. These signals are detected at two positions along the GOCE orbit corresponding to a crossing and a doubling of the infrasonic wavefront created by seismic surface waves. Perturbations up to 11% of air density and 1.35 × 10 - 7 m/s2 of vertical acceleration are observed and modeled with two different solid-atmosphere coupling codes. These perturbations are a due to acoustic waves creating vertical velocities up to 130 m/s. Amplitudes and arrival times of these perturbations are reproduced respectively within a factor 2, and within a 60 s time window. Waveforms present a good agreement with observed data. The vertical acceleration to air density perturbation ratio is higher for these acoustic waves than for gravity waves. Combining these two pieces of information offers a new way to distinguish between these two wave types. This new type of data is a benchmark for the models of solid-atmosphere coupling. Amplitude and frequency content constrain the infrasound attenuation related to atmosphere viscosity and thermal conductivity. Observed time shifts between data and synthetics are ascribed to lateral variations of the seismic and atmospheric sound velocities and to the influence of atmospheric winds. These effects should be included in future modeling. This validation of our modeling tools allows to specify more precisely future observation projects.

TOWARDS RELIABLE AND COST-EFFECTIVE OZONE EXPOSURE ASSESSMENT: PARAMETER EVALUATION AND MODEL VALIDATION USING THE HARVARD SOUTHERN CALIFORNIA CHRONIC OZONE EXPOSURE STUDY DATA

EPA Science Inventory

Accurate assessment of chronic human exposure to atmospheric criteria pollutants, such as ozone, is critical for understanding human health risks associated with living in environments with elevated ambient pollutant concentrations. In this study, we analyzed a data set from a...

Modeling Planetary Atmospheric Energy Deposition By Energetic Ions

NASA Astrophysics Data System (ADS)

Parkinson, Christopher; Bougher, Stephen; Gronoff, Guillaume; Barthelemy, Mathieu

2016-07-01

The structure, dynamics, chemistry, and evolution of planetary upper atmospheres are in large part determined by the available sources of energy. In addition to the solar EUV flux, the solar wind and solar energetic particle (SEP) events are also important sources. Both of these particle populations can significantly affect an atmosphere, causing atmospheric loss and driving chemical reactions. Attention has been paid to these sources from the standpoint of the radiation environment for humans and electronics, but little work has been done to evaluate their impact on planetary atmospheres. At unmagnetized planets or those with crustal field anomalies, in particular, the solar wind and SEPs of all energies have direct access to the atmosphere and so provide a more substantial energy source than at planets having protective global magnetic fields. Additionally, solar wind and energetic particle fluxes should be more significant for planets orbiting more active stars, such as is the case in the early history of the solar system for paleo-Venus and Mars. Therefore quantification of the atmospheric energy input from the solar wind and SEP events is an important component of our understanding of the processes that control their state and evolution. We have applied a full Lorentz motion particle transport model to study the effects of particle precipitation in the upper atmospheres of Mars and Venus. Such modeling has been previously done for Earth and Mars using a guiding center precipitation model. Currently, this code is only valid for particles with small gyroradii in strong uniform magnetic fields. There is a clear necessity for a Lorentz formulation, hence, a systematic study of the ionization, excitation, and energy deposition has been conducted, including a comparison of the influence relative to other energy sources (namely EUV photons). The result is a robust examination of the influence of energetic ion transport on the Venus and Mars upper atmosphere which will be discussed in this presentation.

Technical Report Series on Global Modeling and Data Assimilation. Volume 7: Proceedings of the Workshop on the GEOS-1 Five-year Assimilation

NASA Technical Reports Server (NTRS)

Suarez, Max J. (Editor); Schubert, Siegfried; Rood, Richard

1995-01-01

The primary objective of the three-day workshop on results from the Data Assimilation Office (DAO) five-year assimilation was to provide timely feedback from the data users concerning the strengths and weaknesses of version 1 of the Goddard Earth Observing System (GEOS-1) assimilated products. A second objective was to assess user satisfaction with the current methods of data access and retrieval. There were a total of 49 presentations, with about half (23) of the presentations from scientists from outside of Goddard. The first two days were devoted to applications of data: studies of the energy diagnostics, precipitation and diabatic heating, hydrological modeling and moisture transport, cloud forcing and validation, various aspects of intraseasonal, seasonal, and interannual variability, ocean wind stress applications, and validation of surface fluxes. The last day included talks from the National Meteorological Center (NMC), the National Center for Atmospheric Research (NCAR), the Center for Ocean-Land-Atmosphere Studies (COLA), the United States Navy, and the European Center for Medium Range Weather Forecasts (ECMWF).

Simulating the Cyclone Induced Turbulent Mixing in the Bay of Bengal using COAWST Model

NASA Astrophysics Data System (ADS)

Prakash, K. R.; Nigam, T.; Pant, V.

2017-12-01

Mixing in the upper oceanic layers (up to a few tens of meters from surface) is an important process to understand the evolution of sea surface properties. Enhanced mixing due to strong wind forcing at surface leads to deepening of mixed layer that affects the air-sea exchange of heat and momentum fluxes and modulates sea surface temperature (SST). In the present study, we used Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) model to demonstrate and quantify the enhanced cyclone induced turbulent mixing in case of a severe cyclonic storm. The COAWST model was configured over the Bay of Bengal (BoB) and used to simulate the atmospheric and oceanic conditions prevailing during the tropical cyclone (TC) Phailin that occurred over the BoB during 10-15 October 2013. The model simulated cyclone track was validated with IMD best-track and model SST validated with daily AVHRR SST data. Validation shows that model simulated track & intensity, SST and salinity were in good agreement with observations and the cyclone induced cooling of the sea surface was well captured by the model. Model simulations show a considerable deepening (by 10-15 m) of the mixed layer and shoaling of thermocline during TC Phailin. The power spectrum analysis was performed on the zonal and meridional baroclinic current components, which shows strongest energy at 14 m depth. Model results were analyzed to investigate the non-uniform energy distribution in the water column from surface up to the thermocline depth. The rotary spectra analysis highlights the downward direction of turbulent mixing during the TC Phailin period. Model simulations were used to quantify and interpret the near-inertial mixing, which were generated by cyclone induced strong wind stress and the near-inertial energy. These near-inertial oscillations are responsible for the enhancement of the mixing operative in the strong post-monsoon (October-November) stratification in the BoB.

VOLATILE LOSS AND CLASSIFICATION OF KUIPER BELT OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, R. E.; Schmidt, C.; Oza, A.

Observations indicate that some of the largest Kuiper Belt Objects (KBOs) have retained volatiles in the gas phase (e.g., Pluto), while others have surface volatiles that might support a seasonal atmosphere (e.g., Eris). Since the presence of an atmosphere can affect their reflectance spectra and thermal balance, Schaller and Brown examined the role of volatile escape driven by solar heating of the surface. Guided by recent simulations, we estimate the loss of primordial N{sub 2} for several large KBOs, accounting for escape driven by UV/EUV heating of the upper atmosphere as well as by solar heating of the surface. Formore » the latter we present new simulations and for the former we scale recent detailed simulations of escape from Pluto using the energy limited escape model validated recently by molecular kinetic simulations. Unlike what has been assumed to date, we show that unless the N{sub 2} atmosphere is thin (<∼10{sup 18} N{sub 2} cm{sup −2}) and/or the radius small (<∼200–300 km), escape is primarily driven by the UV/EUV radiation absorbed in the upper atmosphere. This affects the discussion of the relationship between atmospheric loss and the observed surface properties for a number of the KBOs examined. Our long-term goal is to connect detailed atmospheric loss simulations with a model for volatile transport for individual KBOs.« less

An Inequality Constrained Least-Squares Approach as an Alternative Estimation Procedure for Atmospheric Parameters from VLBI Observations

NASA Astrophysics Data System (ADS)

Halsig, Sebastian; Artz, Thomas; Iddink, Andreas; Nothnagel, Axel

2016-12-01

On its way through the atmosphere, radio signals are delayed and affected by bending and attenuation effects relative to a theoretical path in vacuum. In particular, the neutral part of the atmosphere contributes considerably to the error budget of space-geodetic observations. At the same time, space-geodetic techniques become more and more important in the understanding of the Earth's atmosphere, because atmospheric parameters can be linked to the water vapor content in the atmosphere. The tropospheric delay is usually taken into account by applying an adequate model for the hydrostatic component and by additionally estimating zenith wet delays for the highly variable wet component. Sometimes, the Ordinary Least Squares (OLS) approach leads to negative estimates, which would be equivalent to negative water vapor in the atmosphere and does, of course, not reflect meteorological and physical conditions in a plausible way. To cope with this phenomenon, we introduce an Inequality Constrained Least Squares (ICLS) method from the field of convex optimization and use inequality constraints to force the tropospheric parameters to be non-negative allowing for a more realistic tropospheric parameter estimation in a meteorological sense. Because deficiencies in the a priori hydrostatic modeling are almost fully compensated by the tropospheric estimates, the ICLS approach urgently requires suitable a priori hydrostatic delays. In this paper, we briefly describe the ICLS method and validate its impact with regard to station positions.

Dust transport model validation using satellite- and ground-based methods in the southwestern United States

NASA Astrophysics Data System (ADS)

Mahler, Anna-Britt; Thome, Kurt; Yin, Dazhong; Sprigg, William A.

2006-08-01

Dust is known to aggravate respiratory diseases. This is an issue in the desert southwestern United States, where windblown dust events are common. The Public Health Applications in Remote Sensing (PHAiRS) project aims to address this problem by using remote-sensing products to assist in public health decision support. As part of PHAiRS, a model for simulating desert dust cycles, the Dust Regional Atmospheric Modeling (DREAM) system is employed to forecast dust events in the southwestern US. Thus far, DREAM has been validated in the southwestern US only in the lower part of the atmosphere by comparison with measurement and analysis products from surface synoptic, surface Meteorological Aerodrome Report (METAR), and upper-air radiosonde. This study examines the validity of the DREAM algorithm dust load prediction in the desert southwestern United States by comparison with satellite-based MODIS level 2 and MODIS Deep Blue aerosol products, and ground-based observations from the AERONET network of sunphotometers. Results indicate that there are difficulties obtaining MODIS L2 aerosol optical thickness (AOT) data in the desert southwest due to low AOT algorithm performance over areas with high surface reflectances. MODIS Deep Blue aerosol products show improvement, but the temporal and vertical resolution of MODIS data limit its utility for DREAM evaluation. AERONET AOT data show low correlation to DREAM dust load predictions. The potential contribution of space- or ground-based lidar to the PHAiRS project is also examined.

Study of the Effect of Wind Speed on Evaporation from Soil Through Integrated Modeling of Atmospheric Boundary Layer and Shallow Subsurface

NASA Astrophysics Data System (ADS)

Smits, K. M.; Davarzani, H.; Illangasekare, T. H.

2012-12-01

The study of the interaction between the land and atmosphere is paramount to our understanding of many emerging problems to include climate change and the movement of green house gases such as possible leaking of sequestered CO2. Soil moisture distribution in the shallow subsurface becomes a critical factor in these problems. The heat and mass flux in the form of soil evaporation across the land surface couples the atmospheric boundary layer to the shallow subsurface. The coupling between land and the atmosphere leads to highly dynamic interactions between the porous media properties, transport processes and boundary conditions, resulting in dynamic evaporative behavior. However, the coupling at the land-atmospheric interface is rarely considered in most current models and their validation for practical applications. This is due to the complexity of the problem in field scenarios and the scarcity of field or laboratory data capable of testing and refining coupled energy and mass transfer theories. In most efforts to compute evaporation from soil, only indirect coupling is provided to characterize the interaction between non-isothermal multiphase flows under realistic atmospheric conditions even though heat and mass flux are controlled by the coupled dynamics of the land and the atmospheric boundary layer. In earlier drying modeling concepts, imposing evaporation flux (kinetic of relative humidity) and temperature as surface boundary condition is often needed. With the goal of improving our understanding of the land/atmospheric coupling, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model consists of the coupled equations of mass conservation for the liquid phase (water) and gas phase (water vapor and air) in porous medium with gas phase (water vapor and air) in free flow domain under non-isothermal, non-equilibrium conditions. The boundary conditions at the porous medium-free flow medium interface include dynamical, thermal and solutal equilibriums, and using the Beavers-Joseph slip boundary condition. What is unique about this model is that the evaporation rate and soil surface temperature conditions come directly from the model output. In order to experimentally validate the numerical results, we developed and used a unique two dimensional wind tunnel placed above a soil tank equipped with a network of different sensors. A series of experiments under varying boundary conditions were performed. Precision data under well-controlled transient heat and wind boundary conditions was generated. Results from numerical simulations were compared with experimental data. Results demonstrate that the coupling concept can predict the different stages of the drying process in porous media with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time at low velocity values; then, at high values of wind speed the evaporation rate becomes less dependent of flow in free fluid. In the opposite, the impact of the wind speed on the second stage evaporation (diffusion dominant stage) is not significant. The proposed theoretical model can be used to predict the evaporation process where a porous medium flow is coupled to a free flow for different practical applications.

Development of a model to simulate the impact of atmospheric stability on N2O-fluxes from soil

NASA Astrophysics Data System (ADS)

Thieme, Christoph; Klein, Christian; Biernath, Christian; Heinlein, Florian; Priesack, Eckart

2014-05-01

The trace gas N2O, mainly produced by microorganisms in agricultural soils, is a very stable and thus potent greenhouse gas and is the main contributor for the recent depletion of ozone in the stratosphere. Therefore N2O-emissions need to be mitigated and thus much effort has been made to reveal the causes of N2O-formation in soils. At present some crucial drivers for N2O-fluxes are known, but underlying processes of N2O-fluxes are not yet understood or described adequately. An important shortcoming is the description of the upper boundary layer at the soil-atmosphere interface. Therefore, the aim of this study is to develop a mechanistic simulation model, which considers both the formation of N2O in agricultural soils, and the impact of the atmospheric conditions on the transport of soil-born N2O into the atmosphere. The new model simulates N2O-flux as a function of meteorological values instead of a model that just releases the whole amount of N2O into the atmosphere. For this purpose the modular ecosystem model framework Expert-N, which allows to simulate the formation of N2O in the soils will be extended to a model with a more detailed description of the upper boundary condition at the soil-atmosphere interface. In detail, this is realized in the form of a resistance approach, where N2O-fluxes are constrained by a land-air resistance that depends on a Bulk-Exchange Coefficient, wind speed and a gradient of N2O concentrations in the lower atmosphere. Descriptions of atmospheric stability follow the Monin-Obhukov Similarity Theory. The newly developed model will be validated using Eddy Covariance measurements of N2O-fluxes. Measurement device for the N2O concentrations is a Quantum-Cascade-Dual-Laser produced by Aerodyne Research Inc. (Billerca, Mass., USA). The measurements were conducted on an intensively managed field at the TERENO research farm Scheyern (Germany), which is part of the TERENO Bavarian Alps / Pre-Alps observatory.

Airborne and satellite remote sensing of the mid-infrared water vapour continuum.

PubMed

Newman, Stuart M; Green, Paul D; Ptashnik, Igor V; Gardiner, Tom D; Coleman, Marc D; McPheat, Robert A; Smith, Kevin M

2012-06-13

Remote sensing of the atmosphere from space plays an increasingly important role in weather forecasting. Exploiting observations from the latest generation of weather satellites relies on an accurate knowledge of fundamental spectroscopy, including the water vapour continuum absorption. Field campaigns involving the Facility for Airborne Atmospheric Measurements research aircraft have collected a comprehensive dataset, comprising remotely sensed infrared radiance observations collocated with accurate measurements of the temperature and humidity structure of the atmosphere. These field measurements have been used to validate the strength of the infrared water vapour continuum in comparison with the latest laboratory measurements. The recent substantial changes to self-continuum coefficients in the widely used MT_CKD (Mlawer-Tobin-Clough-Kneizys-Davies) model between 2400 and 3200 cm(-1) are shown to be appropriate and in agreement with field measurements. Results for the foreign continuum in the 1300-2000 cm(-1) band suggest a weak temperature dependence that is not currently included in atmospheric models. A one-dimensional variational retrieval experiment is performed that shows a small positive benefit from using new laboratory-derived continuum coefficients for humidity retrievals.

Effects of atmospheric composition on apparent activation energy of silicate weathering: I. Model formulation

NASA Astrophysics Data System (ADS)

Kanzaki, Yoshiki; Murakami, Takashi

2018-07-01

We have developed a weathering model to comprehensively understand the determining factors of the apparent activation energy of silicate weathering in order to better estimate the silicate-weathering flux in the Precambrian. The model formulates the reaction rate of a mineral as a basis, then the elemental loss by summing the reaction rates of whole minerals, and finally the weathering flux from a given weathering profile by integrating the elemental losses along the depth of the profile. The rate expressions are formulated with physicochemical parameters relevant to weathering, including solution and atmospheric compositions. The apparent activation energies of silicate weathering are then represented by the temperature dependences of the physicochemical parameters based on the rate expressions. It was found that the interactions between individual mineral-reactions and the compositions of solution and atmosphere are necessarily accompanied by those of temperature-dependence counterparts. Indeed, the model calculates the apparent activation energy of silicate weathering as a function of the temperature dependence of atmospheric CO2 (Δ HCO2‧) . The dependence of the apparent activation energy of silicate weathering on Δ HCO2‧ may explain the empirical dependence of silicate weathering on the atmospheric composition. We further introduce a compensation law between the apparent activation energy and the pre-exponential factor to obtain the relationship between the silicate-weathering flux (FCO2), temperature and the apparent activation energy. The model calculation and the compensation law enable us to predict FCO2 as a function of temperature, once Δ HCO2‧ is given. The validity of the model is supported by agreements between the model prediction and observations of the apparent activation energy and FCO2 in the modern weathering systems. The present weathering model will be useful for the estimation of FCO2 in the Precambrian, for which Δ HCO2‧ can be deduced from the greenhouse effect of atmospheric CO2.

Computation of diffuse sky irradiance from multidirectional radiance measurements

NASA Technical Reports Server (NTRS)

Ahmad, Suraiya P.; Middleton, Elizabeth M.; Deering, Donald W.

1987-01-01

Accurate determination of the diffuse solar spectral irradiance directly above the land surface is important in characterizing the reflectance properties of these surfaces, especially vegetation canopies. This determination is also needed to infer the net radiation budget of the earth-atmosphere system above these surfaces. An algorithm is developed here for the computation of hemispheric diffuse irradiance using the measurements from an instrument called PARABOLA, which rapidly measures upwelling and downwelling radiances in three selected wavelength bands. The validity of the algorithm is established from simulations. The standard reference data set of diffuse radiances of Dave (1978), obtained by solving the radiative transfer equation numerically for realistic atmospheric models, is used to simulate PARABOLA radiances. Hemispheric diffuse irradiance is estimated from a subset of simulated radiances by using the algorithm described. The algorithm is validated by comparing the estimated diffuse irradiance with the true diffuse irradiance of the standard data set. The validations include sensitivity studies for two wavelength bands (visible, 0.65-0.67 micron; near infrared, 0.81-0.84 micron), different atmospheric conditions, solar elevations, and surface reflectances. In most cases the hemispheric diffuse irradiance computed from simulated PARABOLA radiances and the true irradiance obtained from radiative transfer calculations agree within 1-2 percent. This technique can be applied to other sampling instruments designed to estimate hemispheric diffuse sky irradiance.

A new dynamical atmospheric ionizing radiation (AIR) model for epidemiological studies

NASA Technical Reports Server (NTRS)

De Angelis, G.; Clem, J. M.; Goldhagen, P. E.; Wilson, J. W.

2003-01-01

A new Atmospheric Ionizing Radiation (AIR) model is currently being developed for use in radiation dose evaluation in epidemiological studies targeted to atmospheric flight personnel such as civilian airlines crewmembers. The model will allow computing values for biologically relevant parameters, e.g. dose equivalent and effective dose, for individual flights from 1945. Each flight is described by its actual three dimensional flight profile, i.e. geographic coordinates and altitudes varying with time. Solar modulated primary particles are filtered with a new analytical fully angular dependent geomagnetic cut off rigidity model, as a function of latitude, longitude, arrival direction, altitude and time. The particle transport results have been obtained with a technique based on the three-dimensional Monte Carlo transport code FLUKA, with a special procedure to deal with HZE particles. Particle fluxes are transformed into dose-related quantities and then integrated all along the flight path to obtain the overall flight dose. Preliminary validations of the particle transport technique using data from the AIR Project ER-2 flight campaign of measurements are encouraging. Future efforts will deal with modeling of the effects of the aircraft structure as well as inclusion of solar particle events. Published by Elsevier Ltd on behalf of COSPAR.

An overview of Airborne Data for Assessing Models (ADAM): a web development effort to effectively disseminate airborne data products

NASA Astrophysics Data System (ADS)

Mangosing, D. C.; Chen, G.; Kusterer, J.; Rinsland, P.; Perez, J.; Sorlie, S.; Parker, L.

2011-12-01

One of the objectives of the NASA Langley Research Center's MEaSURES project, "Creating a Unified Airborne Database for Model Assessment", is the development of airborne Earth System Data Records (ESDR) for the regional and global model assessment and validation activities performed by the tropospheric chemistry and climate modeling communities. The ongoing development of ADAM, a web site designed to access a unified, standardized and relational ESDR database, meets this objective. The ESDR database is derived from publically available data sets, from NASA airborne field studies to airborne and in-situ studies sponsored by NOAA, NSF, and numerous international partners. The ADAM web development activities provide an opportunity to highlight a growing synergy between the Airborne Science Data for Atmospheric Composition (ASD-AC) group at NASA Langley and the NASA Langley's Atmospheric Sciences Data Center (ASDC). These teams will collaborate on the ADAM web application by leveraging the state-of-the-art service and message-oriented data distribution architecture developed and implemented by ASDC and using a web-based tool provided by the ASD-AC group whose user interface accommodates the nuanced perspective of science users in the atmospheric chemistry and composition and climate modeling communities.

Cloud-radiation interactions and their parameterization in climate models

NASA Technical Reports Server (NTRS)

1994-01-01

This report contains papers from the International Workshop on Cloud-Radiation Interactions and Their Parameterization in Climate Models met on 18-20 October 1993 in Camp Springs, Maryland, USA. It was organized by the Joint Working Group on Clouds and Radiation of the International Association of Meteorology and Atmospheric Sciences. Recommendations were grouped into three broad areas: (1) general circulation models (GCMs), (2) satellite studies, and (3) process studies. Each of the panels developed recommendations on the themes of the workshop. Explicitly or implicitly, each panel independently recommended observations of basic cloud microphysical properties (water content, phase, size) on the scales resolved by GCMs. Such observations are necessary to validate cloud parameterizations in GCMs, to use satellite data to infer radiative forcing in the atmosphere and at the earth's surface, and to refine the process models which are used to develop advanced cloud parameterizations.

Atmospheric Photochemical Modeling of Turbine Engine Fuels and Exhausts. Phase 2. Computer Model Development. Volume 2

DTIC Science & Technology

1988-05-01

represented name Emitted Organics Included in All Models CO Carbon Monoxide C:C, Ethene HCHO Formaldehyde CCHO Acetaldehyde RCHO Propionaldehyde and other...of species in the mixture, and for proper use of this program, these files should be "normalized," i.e., the number of carbons in the mixture should...scenario in memory. Valid parmtypes are SCEN, PHYS, CHEM, VP, NSP, OUTP, SCHEDS. LIST ALLCOMP Lists all available composition filenames. LIST ALLSCE

Applications of SMART: A DRDC Atmospheric Radiative Transfer Library Optimized for Wide Band Computations

DTIC Science & Technology

2011-06-28

DRDC accurate refracted path calculation – 2-stream (flux) and DISORT (N-stream) MS calculations – Lambert and sea surface (DRDC analytical model ) BRDF ...display a currently valid OMB control number. 1. REPORT DATE 28 JUN 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND...radiance – MODTRAN molecular extinctions (CK) • Seamless integration of MOD4v3r1 – MODTRAN and DRDC aerosol models – Falling snow model (DRDC

Analysis and Validation of a Predictive Model for Growth and Death of Aeromonas hydrophila under Modified Atmospheres at Refrigeration Temperatures

PubMed Central

Pin, Carmen; Velasco de Diego, Raquel; George, Susan; García de Fernando, Gonzalo D.; Baranyi, József

2004-01-01

Specific growth and death rates of Aeromonas hydrophila were measured in laboratory media under various combinations of temperature, pH, and percent CO2 and O2 in the atmosphere. Predictive models were developed from the data and validated by means of observations obtained from (i) seafood experiments set up for this purpose and (ii) the ComBase database (http://www.combase.cc; http://wyndmoor.arserrc.gov/combase/).Two main reasons were identified for the differences between the predicted and observed growth in food: they were the variability of the growth rates in food and the bias of the model predictions when applied to food environments. A statistical method is presented to quantitatively analyze these differences. The method was also used to extend the interpolation region of the model. In this extension, the concept of generalized Z values (C. Pin, G. García de Fernando, J. A. Ordóñez, and J. Baranyi, Food Microbiol. 18:539-545, 2001) played an important role. The extension depended partly on the density of the model-generating observations and partly on the accuracy of extrapolated predictions close to the boundary of the interpolation region. The boundary of the growth region of the organism was also estimated by means of experimental results for growth and death rates. PMID:15240265

Airborne Two-Micron Double-Pulse IPDA Lidar Validation for Carbon Dioxide Measurements Over Land

NASA Astrophysics Data System (ADS)

Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Remus, Ruben; Ismail, Syed

2018-04-01

An airborne double-pulse 2-μm Integrated Path Differential Absorption (IPDA) lidar has been developed at NASA LaRC for measuring atmospheric CO2. IPDA was validated using NASA B-200 aircraft over land and ocean under different conditions. IPDA evaluation for land vegetation returns, during full day background conditions, are presented. IPDA CO2 measurements compare well with model results driven from on-board insitu sensor data. These results also indicate that CO2 measurement bias is consistent with that from ocean surface returns.

Three-dimensional variations of atmospheric CO2: aircraft measurements and multi-transport model simulations

NASA Astrophysics Data System (ADS)

Niwa, Y.; Patra, P. K.; Sawa, Y.; Machida, T.; Matsueda, H.; Belikov, D.; Maki, T.; Ikegami, M.; Imasu, R.; Maksyutov, S.; Oda, T.; Satoh, M.; Takigawa, M.

2011-12-01

Numerical simulation and validation of three-dimensional structure of atmospheric carbon dioxide (CO2) is necessary for quantification of transport model uncertainty and its role on surface flux estimation by inverse modeling. Simulations of atmospheric CO2 were performed using four transport models and two sets of surface fluxes compared with an aircraft measurement dataset of Comprehensive Observation Network for Trace gases by AIrLiner (CONTRAIL), covering various latitudes, longitudes, and heights. Under this transport model intercomparison project, spatiotemporal variations of CO2 concentration for 2006-2007 were analyzed with a three-dimensional perspective. Results show that the models reasonably simulated vertical profiles and seasonal variations not only over northern latitude areas but also over the tropics and southern latitudes. From CONTRAIL measurements and model simulations, intrusion of northern CO2 in to the Southern Hemisphere, through the upper troposphere, was confirmed. Furthermore, models well simulated the vertical propagation of seasonal variation in the northern free troposphere. However, significant model-observation discrepancies were found in Asian regions, which are attributable to uncertainty of the surface CO2 flux data. In summer season, differences in latitudinal gradients by the fluxes are comparable to or greater than model-model differences even in the free troposphere. This result suggests that active summer vertical transport sufficiently ventilates flux signals up to the free troposphere and the models could use those for inferring surface CO2 fluxes.

Multi-level emulation of complex climate model responses to boundary forcing data

NASA Astrophysics Data System (ADS)

Tran, Giang T.; Oliver, Kevin I. C.; Holden, Philip B.; Edwards, Neil R.; Sóbester, András; Challenor, Peter

2018-04-01

Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1's energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM's spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.

Global Clear-Sky Surface Skin Temperature from Multiple Satellites Using a Single-Channel Algorithm with Angular Anisotropy Corrections

NASA Technical Reports Server (NTRS)

Scarino, Benjamin R.; Minnis, Patrick; Chee, Thad; Bedka, Kristopher M.; Yost, Christopher R.; Palikonda, Rabindra

2017-01-01

Surface skin temperature (T(sub s)) is an important parameter for characterizing the energy exchange at the ground/water-atmosphere interface. The Satellite ClOud and Radiation Property retrieval System (SatCORPS) employs a single-channel thermal-infrared (TIR) method to retrieve T(sub s) over clear-sky land and ocean surfaces from data taken by geostationary Earth orbit (GEO) and low Earth orbit (LEO) satellite imagers. GEO satellites can provide somewhat continuous estimates of T(sub s) over the diurnal cycle in non-polar regions, while polar T(sub s) retrievals from LEO imagers, such as the Advanced Very High Resolution Radiometer (AVHRR), can complement the GEO measurements. The combined global coverage of remotely sensed T(sub s), along with accompanying cloud and surface radiation parameters, produced in near-realtime and from historical satellite data, should be beneficial for both weather and climate applications. For example, near-realtime hourly T(sub s) observations can be assimilated in high-temporal-resolution numerical weather prediction models and historical observations can be used for validation or assimilation of climate models. Key drawbacks to the utility of TIR-derived T(sub s) data include the limitation to clear-sky conditions, the reliance on a particular set of analyses/reanalyses necessary for atmospheric corrections, and the dependence on viewing and illumination angles. Therefore, T(sub s) validation with established references is essential, as is proper evaluation of T(sub s) sensitivity to atmospheric correction source. This article presents improvements on the NASA Langley GEO satellite and AVHRR TIR-based T(sub s) product that is derived using a single-channel technique. The resulting clear-sky skin temperature values are validated with surface references and independent satellite products. Furthermore, an empirically adjusted theoretical model of satellite land surface temperature (LST) angular anisotropy is tested to improve satellite LST retrievals. Application of the anisotropic correction yields reduced mean bias and improved precision of GOES-13 LST relative to independent Moderate-resolution Imaging Spectroradiometer (MYD11_L2) LST and Atmospheric Radiation Measurement Program ground station measurements. It also significantly reduces inter-satellite differences between LSTs retrieved simultaneously from two different imagers. The implementation of these universal corrections into the SatCORPS product can yield significant improvement in near-global-scale, near-realtime, satellite-based LST measurements. The immediate availability and broad coverage of these skin temperature observations should prove valuable to modelers and climate researchers looking for improved forecasts and better understanding of the global climate model.

GARLIC - A general purpose atmospheric radiative transfer line-by-line infrared-microwave code: Implementation and evaluation

NASA Astrophysics Data System (ADS)

Schreier, Franz; Gimeno García, Sebastián; Hedelt, Pascal; Hess, Michael; Mendrok, Jana; Vasquez, Mayte; Xu, Jian

2014-04-01

A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code - GARLIC - is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments. This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus.

Simulated Martian pressure cycle based on the sublimation and deposition of polar CO2

NASA Astrophysics Data System (ADS)

Kemppinen, Osku; Paton, Mark; Savijärvi, Hannu; Harri, Ari-Matti

2014-05-01

The Martian atmospheric pressure cycle is driven by sublimation and deposition of CO2 at polar caps. In the thin atmosphere of Mars the surface energy balance and thus the phase changes of CO2 are dominated by radiation. Additionally, because the atmosphere is so thin, the annual polar cap cycle can have a large relative effect on the pressure. In this work we utilize radiative transfer models to calculate the amount of radiation incoming to Martian polar latitudes over each sol of the year, as well as the amount of energy lost from the surface due to thermal radiation. The energy budget calculated in this way allows us to estimate the amount of CO2 sublimating and depositing at each hour of the Martian year. Since virtually all of the sublimated CO2 is believed to enter and stay in the atmosphere until depositing, this estimate allows us to calculate the annual pressure cycle, assuming that the CO2 is distributed approximately evenly over the planet. The model is running with physically plausible parameters and producing encouragingly good fits to in situ measured data made by e.g. Viking landers. In the next phase we will validate the simulation runs against polar ice cap thickness measurements as well as compare the calculated CO2 source and sink strengths to the sources and sinks of global atmospheric models.

Cloud Radiation Forcings and Feedbacks: General Circulation Model Tests and Observational Validation

NASA Technical Reports Server (NTRS)

Lee,Wan-Ho; Iacobellis, Sam F.; Somerville, Richard C. J.

1997-01-01

Using an atmospheric general circulation model (the National Center for Atmospheric Research Community Climate Model: CCM2), the effects on climate sensitivity of several different cloud radiation parameterizations have been investigated. In addition to the original cloud radiation scheme of CCM2, four parameterizations incorporating prognostic cloud water were tested: one version with prescribed cloud radiative properties and three other versions with interactive cloud radiative properties. The authors' numerical experiments employ perpetual July integrations driven by globally constant sea surface temperature forcings of two degrees, both positive and negative. A diagnostic radiation calculation has been applied to investigate the partial contributions of high, middle, and low cloud to the total cloud radiative forcing, as well as the contributions of water vapor, temperature, and cloud to the net climate feedback. The high cloud net radiative forcing is positive, and the middle and low cloud net radiative forcings are negative. The total net cloud forcing is negative in all of the model versions. The effect of interactive cloud radiative properties on global climate sensitivity is significant. The net cloud radiative feedbacks consist of quite different shortwave and longwave components between the schemes with interactive cloud radiative properties and the schemes with specified properties. The increase in cloud water content in the warmer climate leads to optically thicker middle- and low-level clouds and in turn to negative shortwave feedbacks for the interactive radiative schemes, while the decrease in cloud amount simply produces a positive shortwave feedback for the schemes with a specified cloud water path. For the longwave feedbacks, the decrease in high effective cloudiness for the schemes without interactive radiative properties leads to a negative feedback, while for the other cases, the longwave feedback is positive. These cloud radiation parameterizations are empirically validated by using a single-column diagnostic model. together with measurements from the Atmospheric Radiation Measurement program and from the Tropical Ocean Global Atmosphere Combined Ocean-Atmosphere Response Experiment. The inclusion of prognostic cloud water produces a notable improvement in the realism of the parameterizations, as judged by these observations. Furthermore, the observational evidence suggests that deriving cloud radiative properties from cloud water content and microphysical characteristics is a promising route to further improvement.

Advanced Space Shuttle simulation model

NASA Technical Reports Server (NTRS)

Tatom, F. B.; Smith, S. R.

1982-01-01

A non-recursive model (based on von Karman spectra) for atmospheric turbulence along the flight path of the shuttle orbiter was developed. It provides for simulation of instantaneous vertical and horizontal gusts at the vehicle center-of-gravity, and also for simulation of instantaneous gusts gradients. Based on this model the time series for both gusts and gust gradients were generated and stored on a series of magnetic tapes, entitled Shuttle Simulation Turbulence Tapes (SSTT). The time series are designed to represent atmospheric turbulence from ground level to an altitude of 120,000 meters. A description of the turbulence generation procedure is provided. The results of validating the simulated turbulence are described. Conclusions and recommendations are presented. One-dimensional von Karman spectra are tabulated, while a discussion of the minimum frequency simulated is provided. The results of spectral and statistical analyses of the SSTT are presented.

Application of the Analog Method to Modelling Heat Waves: A Case Study with Power Transformers

DTIC Science & Technology

2017-04-21

UNCLASSIFIED Massachusetts Institute of Technology Lincoln Laboratory APPLICATION OF THE ANALOG METHOD TO MODELLING HEAT WAVES: A CASE STUDY WITH...18 2 Calibration and validation statistics with the use of five atmospheric vari- ables to construct analogue diagnostics for JJA of transformer T2...electrical grid as a series of nodes (transformers) and edges (transmission lines) so that basic mathematical anal- ysis can be performed. The mathematics

Simple, accurate formula for the average bit error probability of multiple-input multiple-output free-space optical links over negative exponential turbulence channels.

PubMed

Peppas, Kostas P; Lazarakis, Fotis; Alexandridis, Antonis; Dangakis, Kostas

2012-08-01

In this Letter we investigate the error performance of multiple-input multiple-output free-space optical communication systems employing intensity modulation/direct detection and operating over strong atmospheric turbulence channels. Atmospheric-induced strong turbulence fading is modeled using the negative exponential distribution. For the considered system, an approximate yet accurate analytical expression for the average bit error probability is derived and an efficient method for its numerical evaluation is proposed. Numerically evaluated and computer simulation results are further provided to demonstrate the validity of the proposed mathematical analysis.

Validation of the Atmospheric Infrared Sounder (AIRS) over the Antarctic Plateau: Low Radiance, Low Humidity, and Thin Clouds

NASA Technical Reports Server (NTRS)

Tobin, David C.

2005-01-01

The main goal of the project has been to use specialized measurements collected at the Antarctic Plateau to provide validation of the Atmospheric InfraRed Sounder (AIRS) spectral radiances and some AIRS Level 2 products. As proposed, efforts conducted at the University of Wisconsin are focused on providing technical information, data, and software in support of the validation studies.

The Response of High Energy Photoelectrons in The Mars Atmosphere to Variable Solar Input

NASA Astrophysics Data System (ADS)

Mills, I. F.; Eparvier, F. G.; Thiemann, E.; Mitchell, D. L.

2016-12-01

The Mars Atmosphere and Volatile Evolution (MAVEN) mission aims to understand the processes by which Mars has been losing atmosphere over time by analyzing data taken from different levels of the Martian atmosphere as well as solar drivers. In this project, we isolate data taken from the ionosphere to study high-energy electrons created by a particular ionization process called the Auger effect. This process occurs when soft x-rays ionize atmospheric gases. In particular, we focus on Auger electrons that are ionized from CO2 molecules and atomic O via solar irradiance in the 0.1-6 nm wavelength range. Thus far, the portion of the solar spectrum that produces Auger electrons has been sparsely measured and its spectral distribution is poorly understood, especially as a function of solar activity. To make up for this, models of spectral irradiance are used in studies of atmospheric effects. In an effort to validate solar irradiance models from 0.1- 6 nm, we utilize data from two instruments on board the MAVEN spacecraft, EUVM (the Extreme Ultraviolet Monitor), which measures the broadband solar irradiance from 0.1-6 nm and SWEA (the Solar Wind Electron Analyzer), which measures the photoelectron energy spectrum in the Mars atmosphere. We then compare these observed data sets to two different spectral irradiance models: MAVEN SynRef, and FISM-M (the Flare Irradiance Spectral Model for Mars). SynRef is a version of the SORCE XPS model modified to be used by MAVEN/EUVM, and FISM-M is a version of the FISM proxy model previously developed for Earth irradiance and modified to be used by MAVEN/EUVM. Our method of comparison is to find the Pearson correlation between the data and the models over October 2015, a month that had a strong solar rotational variability in the solar irradiance. By filtering the SWEA data for different altitudes and solar zenith angles, we are able to analyze how Auger electrons react under different solar activity levels. Both irradiance models correlate well with the electron data, specifically when comparing them with electrons in the bin containing the Auger peak, and when integrating over multiple energy bins surrounding this peak.

Current Status of the Validation of the Atmospheric Chemistry Instruments on Envisat

NASA Astrophysics Data System (ADS)

Lecomte, P.; Koopman, R.; Zehner, C.; Laur, H.; Attema, E.; Wursteisen, P.; Snoeij, P.

2003-04-01

Envisat is ESA's advanced Earth observing satellite launched in March 2002 and is designed to provide measurements of the atmosphere, ocean, land and ice over a five-year period. After the launch and the switch-on period, a six-month commissioning phase has taken place for instrument calibration and geophysical validation, concluded with the Envisat Calibration Review held in September 2002. In addition to ESA and its industrial partners in the Envisat consortium, many other companies and research institutes have contributed to the calibration and validation programme under ESA contract as expert support laboratories (ESLs). A major contribution has also been made by the Principal Investigators of approved proposals submitted to ESA in response to a worldwide "Announcement of Opportunity for the Exploitation of the Envisat Data Products" in 1998. Working teams have been formed in which the different participants worked side by side to achieve the objectives of the calibration and validation programme. Validation is a comparison of Envisat level-2 data products and estimates of the different geophysical variables obtained by independent means, the validation instruments. Validation is closely linked to calibration because inconsistencies discovered in the comparison of Envisat Level 2 data products to well-known external instruments can have many different sources, including inaccuracies of the Envisat instrument calibration and the data calibration algorithms. Therefore, initial validation of the geophysical variables has provided feedback to calibration, de-bugging and algorithm improvement. The initial validation phase ended in December 2002 with the Envisat Validation Workshop at which, for a number of products, a final quality statement was given. Full validation of all data products available from the Atmospheric Chemistry Instruments on Envisat (MIPAS, GOMOS and SCIAMACHY) is quite a challenge and therefore it has been decided to adopt a step-wise approach. As a first step the intention is to arrive at a first quality assessment of the data products for near-real time distribution. This core validation was performed during the commissioning and validation phase of Envisat. The results of this exercise have been presented at the Envisat Validation Workshop. It was already anticipated early in the program that more work needed to be done after this workshop on all Envisat data products both for near-real time and for off-line distribution. The algorithms designed to derive estimates of the atmospheric constitutes need to be verified. For this a large number of correlative observations under a wide range of conditions are needed to arrive at a representative and statistically significant data quality assessment, and to provide insight into sources of error both in the Envisat data and the correlative data sets. In order to achieve this within the tight time schedule the best use must be made of the available resources. For the Atmospheric Chemistry Instruments on Envisat it has therefore been decided to plan a joint geophysical validation programme that is not instrument specific but serves all three instruments. For the co-ordination of the activities the Atmospheric Chemistry Validation Team was formed (ACVT). The ACVT methods can roughly be categorised into different approaches and consistent with these the group is divided into different subgroups on · balloon and aircraft campaigns · ground-based measurements · model assimilation and satellite intercomparison The data coming from the various validation campaigns are stored within a central data storage facility established at the Norwegian Institute for Air Research (NILU) in Norway. NILU provides access to correlative measurements from sensors on-board satellites, aircraft, balloons and ships, as well as from ground-based instruments and numerical models, such as that of the ECMWF. Particular emphasis has been put on the quality control of such data. Users are able to connect with the database to add or retrieve data according to their requirements. Access to such a range of data have strengthened the statistical significance of the results and increased the chances of detecting errors in the processing algorithms. Two types of data are stored in the NILU database, fixed point and transect data. Transect data is only provided for inclusion in the database for selected times which correspond to the satellite overpass. Envisat data is not stored in the NILU database although other correlative satellite data is included to facilitate their comparison with data acquired by Envisat. The European Space Agency (ESA) organised a workshop in Frascati from 9 to 13 December 2002 to review the first results of the validation of the geophysical data products from its environmental satellite Envisat. The objectives of the Envisat Validation Workshop were: . to review the Level 2 product algorithms using the results of the validation campaigns, . to review the geophysical consistency of the Level 2 processor products, . to provide an error estimation of the Level 2 products, . to recommend instrument re-calibration and algorithm development where needed. At the Envisat Validation workshop held in Frascati, Italy, from 9-13 December, scientists and engineers presented analyses of the exhaustive series of tests that have been run on each of Envisat's sensors since the spacecraft was launched in March. On the basis of workshop results it was decided that most of the 73 data products provided by the Envisat instruments are ready for operational delivery. Although the main validation phase for the atmospheric instruments of Envisat will be completed this year, ongoing validation products will continue throughout the lifetime of the Envisat mission. More specifically, the main validation phase (i.e. with intensive validation activities) will be completed in 2003, whereas the long-term validation phase will: - Provide assurance of data quality and accuracy for applications such as climate change research - Investigate the fully representative range of geophysical conditions - Investigate the fully representative range of seasonal cycles - Perform long term monitoring for instrumental drifts and other artefacts - Validate new products. The paper will discuss the general status of the calibration and validation activities for GOMOS, MIPAS and SCIAMACHY. The short-term and long-term validation plans will be presented.

Time Domain Tool Validation Using ARES I-X Flight Data

NASA Technical Reports Server (NTRS)

Hough, Steven; Compton, James; Hannan, Mike; Brandon, Jay

2011-01-01

The ARES I-X vehicle was launched from NASA's Kennedy Space Center (KSC) on October 28, 2009 at approximately 11:30 EDT. ARES I-X was the first test flight for NASA s ARES I launch vehicle, and it was the first non-Shuttle launch vehicle designed and flown by NASA since Saturn. The ARES I-X had a 4-segment solid rocket booster (SRB) first stage and a dummy upper stage (US) to emulate the properties of the ARES I US. During ARES I-X pre-flight modeling and analysis, six (6) independent time domain simulation tools were developed and cross validated. Each tool represents an independent implementation of a common set of models and parameters in a different simulation framework and architecture. Post flight data and reconstructed models provide the means to validate a subset of the simulations against actual flight data and to assess the accuracy of pre-flight dispersion analysis. Post flight data consists of telemetered Operational Flight Instrumentation (OFI) data primarily focused on flight computer outputs and sensor measurements as well as Best Estimated Trajectory (BET) data that estimates vehicle state information from all available measurement sources. While pre-flight models were found to provide a reasonable prediction of the vehicle flight, reconstructed models were generated to better represent and simulate the ARES I-X flight. Post flight reconstructed models include: SRB propulsion model, thrust vector bias models, mass properties, base aerodynamics, and Meteorological Estimated Trajectory (wind and atmospheric data). The result of the effort is a set of independently developed, high fidelity, time-domain simulation tools that have been cross validated and validated against flight data. This paper presents the process and results of high fidelity aerospace modeling, simulation, analysis and tool validation in the time domain.

The resistance of the lichen Circinaria gyrosa (nom. provis.) towards simulated Mars conditions—a model test for the survival capacity of an eukaryotic extremophile

NASA Astrophysics Data System (ADS)

Sánchez, F. J.; Mateo-Martí, E.; Raggio, J.; Meeßen, J.; Martínez-Frías, J.; Sancho, L. G.^a..; Ott, S.; de la Torre, R.

2012-11-01

The "Planetary Atmospheres and Surfaces Chamber" (PASC, at Centro de Astrobiología, INTA, Madrid) is able to simulate the atmosphere and surface temperature of most of the solar system planets. PASC is especially appropriate to study irradiation induced changes of geological, chemical, and biological samples under a wide range of controlled atmospheric and temperature conditions. Therefore, PASC is a valid method to test the resistance potential of extremophile organisms under diverse harsh conditions and thus assess the habitability of extraterrestrial environments. In the present study, we have investigated the resistance of a symbiotic organism under simulated Mars conditions, exemplified with the lichen Circinaria gyrosa - an extremophilic eukaryote. After 120 hours of exposure to simulated but representative Mars atmosphere, temperature, pressure and UV conditions; an unaltered photosynthetic performance demonstrated high resistance of the lichen photobiont.

Validation and optimization of SST k-ω turbulence model for pollutant dispersion within a building array

NASA Astrophysics Data System (ADS)

Yu, Hesheng; Thé, Jesse

2016-11-01

The prediction of the dispersion of air pollutants in urban areas is of great importance to public health, homeland security, and environmental protection. Computational Fluid Dynamics (CFD) emerges as an effective tool for pollutant dispersion modelling. This paper reports and quantitatively validates the shear stress transport (SST) k-ω turbulence closure model and its transitional variant for pollutant dispersion under complex urban environment for the first time. Sensitivity analysis is performed to establish recommendation for the proper use of turbulence models in urban settings. The current SST k-ω simulation is validated rigorously by extensive experimental data using hit rate for velocity components, and the "factor of two" of observations (FAC2) and fractional bias (FB) for concentration field. The simulation results show that current SST k-ω model can predict flow field nicely with an overall hit rate of 0.870, and concentration dispersion with FAC2 = 0.721 and FB = 0.045. The flow simulation of the current SST k-ω model is slightly inferior to that of a detached eddy simulation (DES), but better than that of standard k-ε model. However, the current study is the best among these three model approaches, when validated against measurements of pollutant dispersion in the atmosphere. This work aims to provide recommendation for proper use of CFD to predict pollutant dispersion in urban environment.

Influence of variable selection on partial least squares discriminant analysis models for explosive residue classification

NASA Astrophysics Data System (ADS)

De Lucia, Frank C., Jr.; Gottfried, Jennifer L.

2011-02-01

Using a series of thirteen organic materials that includes novel high-nitrogen energetic materials, conventional organic military explosives, and benign organic materials, we have demonstrated the importance of variable selection for maximizing residue discrimination with partial least squares discriminant analysis (PLS-DA). We built several PLS-DA models using different variable sets based on laser induced breakdown spectroscopy (LIBS) spectra of the organic residues on an aluminum substrate under an argon atmosphere. The model classification results for each sample are presented and the influence of the variables on these results is discussed. We found that using the whole spectra as the data input for the PLS-DA model gave the best results. However, variables due to the surrounding atmosphere and the substrate contribute to discrimination when the whole spectra are used, indicating this may not be the most robust model. Further iterative testing with additional validation data sets is necessary to determine the most robust model.

Modeling Martian Dust Using Mars-GRAM

NASA Technical Reports Server (NTRS)

Justh, Hilary L.; Justus, C. G.

2010-01-01

Engineering-level atmospheric model widely used for diverse mission applications. Mars-GRAM s perturbation modeling capability is commonly used, in a Monte-Carlo mode, to perform high fidelity engineering end-to-end simulations for entry, descent, and landing (EDL). From the surface to 80 km altitude, Mars-GRAM is based on NASA Ames Mars General Circulation Model (MGCM). Mars-GRAM and MGCM use surface topography from Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA), with altitudes referenced to the MOLA areoid, or constant potential surface. Traditional Mars-GRAM options for representing the mean atmosphere along entry corridors include: TES Mapping Years 1 and 2, with Mars-GRAM data coming from MGCM model results driven by observed TES dust optical depth TES Mapping Year 0, with user-controlled dust optical depth and Mars-GRAM data interpolated from MGCM model results driven by selected values of globally-uniform dust optical depth. Mars-GRAM 2005 has been validated against Radio Science data, and both nadir and limb data from the Thermal Emission Spectrometer (TES).

A new spherical model for computing the radiation field available for photolysis and heating at twilight

NASA Technical Reports Server (NTRS)

Dahlback, Arne; Stamnes, Knut

1991-01-01

Accurate computation of atmospheric photodissociation and heating rates is needed in photochemical models. These quantities are proportional to the mean intensity of the solar radiation penetrating to various levels in the atmosphere. For large solar zenith angles a solution of the radiative transfer equation valid for a spherical atmosphere is required in order to obtain accurate values of the mean intensity. Such a solution based on a perturbation technique combined with the discrete ordinate method is presented. Mean intensity calculations are carried out for various solar zenith angles. These results are compared with calculations from a plane parallel radiative transfer model in order to assess the importance of using correct geometry around sunrise and sunset. This comparison shows, in agreement with previous investigations, that for solar zenith angles less than 90 deg adequate solutions are obtained for plane parallel geometry as long as spherical geometry is used to compute the direct beam attenuation; but for solar zenith angles greater than 90 deg this pseudospherical plane parallel approximation overstimates the mean intensity.

Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures: SBIR Phase I Final Report

NASA Technical Reports Server (NTRS)

Likhanskii, Alexandre

2012-01-01

This report is the final report of a SBIR Phase I project. It is identical to the final report submitted, after some proprietary information of administrative nature has been removed. The development of a numerical simulation tool for dielectric barrier discharge (DBD) plasma actuator is reported. The objectives of the project were to analyze and predict DBD operation at wide range of ambient gas pressures. It overcomes the limitations of traditional DBD codes which are limited to low-speed applications and have weak prediction capabilities. The software tool allows DBD actuator analysis and prediction for subsonic to hypersonic flow regime. The simulation tool is based on the VORPAL code developed by Tech-X Corporation. VORPAL's capability of modeling DBD plasma actuator at low pressures (0.1 to 10 torr) using kinetic plasma modeling approach, and at moderate to atmospheric pressures (1 to 10 atm) using hydrodynamic plasma modeling approach, were demonstrated. In addition, results of experiments with pulsed+bias DBD configuration that were performed for validation purposes are reported.

Exploiting the chaotic behaviour of atmospheric models with reconfigurable architectures

NASA Astrophysics Data System (ADS)

Russell, Francis P.; Düben, Peter D.; Niu, Xinyu; Luk, Wayne; Palmer, T. N.

2017-12-01

Reconfigurable architectures are becoming mainstream: Amazon, Microsoft and IBM are supporting such architectures in their data centres. The computationally intensive nature of atmospheric modelling is an attractive target for hardware acceleration using reconfigurable computing. Performance of hardware designs can be improved through the use of reduced-precision arithmetic, but maintaining appropriate accuracy is essential. We explore reduced-precision optimisation for simulating chaotic systems, targeting atmospheric modelling, in which even minor changes in arithmetic behaviour will cause simulations to diverge quickly. The possibility of equally valid simulations having differing outcomes means that standard techniques for comparing numerical accuracy are inappropriate. We use the Hellinger distance to compare statistical behaviour between reduced-precision CPU implementations to guide reconfigurable designs of a chaotic system, then analyse accuracy, performance and power efficiency of the resulting implementations. Our results show that with only a limited loss in accuracy corresponding to less than 10% uncertainty in input parameters, the throughput and energy efficiency of a single-precision chaotic system implemented on a Xilinx Virtex-6 SX475T Field Programmable Gate Array (FPGA) can be more than doubled.

Photolysis Rate Coefficient Calculations in Support of SOLVE Campaign

NASA Technical Reports Server (NTRS)

Lloyd, Steven A.; Swartz, William H.

2001-01-01

The objectives for this SOLVE project were 3-fold. First, we sought to calculate a complete set of photolysis rate coefficients (j-values) for the campaign along the ER-2 and DC-8 flight tracks. En route to this goal, it would be necessary to develop a comprehensive set of input geophysical conditions (e.g., ozone profiles), derived from various climatological, aircraft, and remotely sensed datasets, in order to model the radiative transfer of the atmosphere accurately. These j-values would then need validation by comparison with flux-derived j-value measurements. The second objective was to analyze chemistry along back trajectories using the NASA/Goddard chemistry trajectory model initialized with measurements of trace atmospheric constituents. This modeling effort would provide insight into the completeness of current measurements and the chemistry of Arctic wintertime ozone loss. Finally, we sought to coordinate stellar occultation measurements of ozone (and thus ozone loss) during SOLVE using the MSX/UVISI satellite instrument. Such measurements would determine ozone loss during the Arctic polar night and represent the first significant science application of space-based stellar occultation in the Earth's atmosphere.

Simple additive effects are rare: A quantitative review of plant biomass and soil process responses to combined manipulations of CO2 and temperature

USDA-ARS?s Scientific Manuscript database

In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([CO2]) and temperature has illustrated the importance of multi-factorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased u...

Validation of SMAP soil moisture for the SMAPVEX15 field campaign using a hyper-resolution model

USDA-ARS?s Scientific Manuscript database

Accurate global mapping of soil moisture is the goal of the Soil Moisture Active Passive (SMAP) mission, which is expected to improve the estimation of water, energy, and carbon exchanges between the land and the atmosphere. Like other satellite products, the SMAP soil moisture retrievals need to be...

Retrieval of an available water-based soil moisture proxy from thermal infrared remote sensing. Part I: Methodology and validation

USDA-ARS?s Scientific Manuscript database

A retrieval of soil moisture is proposed using surface flux estimates from satellite-based thermal infrared (TIR) imagery and the Atmosphere-Land-Exchange-Inversion (ALEXI) model. The ability of ALEXI to provide valuable information about the partitioning of the surface energy budget, which can be l...

Three-dimensional variations of atmospheric CO2: aircraft measurements and multi-transport model simulations

NASA Astrophysics Data System (ADS)

Niwa, Y.; Patra, P. K.; Sawa, Y.; Machida, T.; Matsueda, H.; Belikov, D.; Maki, T.; Ikegami, M.; Imasu, R.; Maksyutov, S.; Oda, T.; Satoh, M.; Takigawa, M.

2011-04-01

Numerical simulation and validation of three-dimensional structure of atmospheric carbon dioxide (CO2) is necessary for quantification of transport model uncertainty and its role on surface flux estimation by inverse modeling. Simulations of atmospheric CO2 were performed using four transport models and two sets of surface fluxes compared with an aircraft measurement dataset of Comprehensive Observation Network for Trace gases by AIrLiner (CONTRAIL), covering various latitudes, longitudes, and heights. Under this transport model intercomparison project, spatiotemporal variations of CO2 concentration for 2006-2007 were analyzed with a three-dimensional perspective. Results show that the models reasonably simulated vertical profiles and seasonal variations not only over northern latitude areas but also over the tropics and southern latitudes. From CONTRAIL measurements and model simulations, intrusion of northern CO2 in to the Southern Hemisphere, through the upper troposphere, was confirmed. Furthermore, models well simulated the vertical propagation of seasonal variation in the northern free-troposphere. However, significant model-observation discrepancies were found in Asian regions, which are attributable to uncertainty of the surface CO2 flux data. The models consistently underestimated the north-tropics mean gradient of CO2 both in the free-troposphere and marine boundary layer during boreal summer. This result suggests that the north-tropics contrast of annual mean net non-fossil CO2 flux should be greater than 2.7 Pg C yr-1 for 2007.

National Atmospheric Release Advisory Center dispersion modeling of the Full-scale Radiological Dispersal device (FSRDD) field trials

DOE PAGES

Neuscamman, Stephanie J.; Yu, Kristen L.

2016-05-01

The results of the National Atmospheric Release Advisory Center (NARAC) model simulations are compared to measured data from the Full-Scale Radiological Dispersal Device (FSRDD) field trials. The series of explosive radiological dispersal device (RDD) experiments was conducted in 2012 by Defence Research and Development Canada (DRDC) and collaborating organizations. During the trials, a wealth of data was collected, including a variety of deposition and air concentration measurements. The experiments were conducted with one of the stated goals being to provide measurements to atmospheric dispersion modelers. These measurements can be used to facilitate important model validation studies. For this study, meteorologicalmore » observations recorded during the tests are input to the diagnostic meteorological model, ADAPT, which provides 3–D, time-varying mean wind and turbulence fields to the LODI dispersion model. LODI concentration and deposition results are compared to the measured data, and the sensitivity of the model results to changes in input conditions (such as the particle activity size distribution of the source) and model physics (such as the rise of the buoyant cloud of explosive products) is explored. The NARAC simulations predicted the experimentally measured deposition results reasonably well considering the complexity of the release. Lastly, changes to the activity size distribution of the modeled particles can improve the agreement of the model results to measurement.« less

Transmission Spectra of Transiting Planet Atmospheres: Model Validation and Simulations of the Hot Neptune GJ 436b for the James Webb Space Telescope

NASA Astrophysics Data System (ADS)

Shabram, Megan; Fortney, Jonathan J.; Greene, Thomas P.; Freedman, Richard S.

2011-02-01

We explore the transmission spectrum of the Neptune-class exoplanet GJ 436b, including the possibility that its atmospheric opacity is dominated by a variety of nonequilibrium chemical products. We also validate our transmission code by demonstrating close agreement with analytic models that use only Rayleigh scattering or water vapor opacity. We find broad disagreement with radius variations predicted by another published model. For GJ 436b, the relative coolness of the planet's atmosphere, along with its implied high metallicity, may make it dissimilar in character compared to "hot Jupiters." Some recent observational and modeling efforts suggest low relative abundances of H2O and CH4 present in GJ 436b's atmosphere, compared to calculations from equilibrium chemistry. We include these characteristics in our models and examine the effects of absorption from methane-derived higher-order hydrocarbons. To our knowledge, the effects of these nonequilibrium chemical products on the spectra of close-in giant planets have not previously been investigated. Significant absorption from HCN and C2H2 is found throughout the infrared, while C2H4 and C2H6 are less easily seen. We perform detailed simulations of James Webb Space Telescope observations, including all likely noise sources, and find that we will be able to constrain chemical abundance regimes from this planet's transmission spectrum. For instance, the width of the features at 1.5, 3.3, and 7 μm indicates the amount of HCN versus C2H2 present. The NIRSpec prism mode will be useful due to its large spectral range and the relatively large number of photo-electrons recorded per spectral resolution element. However, extremely bright host stars like GJ 436 may be better observed with a higher spectroscopic resolution mode in order to avoid detector saturation. We find that observations with the MIRI low-resolution spectrograph should also have high signal-to-noise in the 5-10 μm range due to the brightness of the star and the relatively low spectral resolution (R ~ 100) of this mode.

Effects of different representations of transport in the new EMAC-SWIFT chemistry climate model

NASA Astrophysics Data System (ADS)

Scheffler, Janice; Langematz, Ulrike; Wohltmann, Ingo; Kreyling, Daniel; Rex, Markus

2017-04-01

It is well known that the representation of atmospheric ozone chemistry in weather and climate models is essential for a realistic simulation of the atmospheric state. Interactively coupled chemistry climate models (CCMs) provide a means to realistically simulate the interaction between atmospheric chemistry and dynamics. The calculation of chemistry in CCMs, however, is computationally expensive which renders the use of complex chemistry models not suitable for ensemble simulations or simulations with multiple climate change scenarios. In these simulations ozone is therefore usually prescribed as a climatological field or included by incorporating a fast linear ozone scheme into the model. While prescribed climatological ozone fields are often not aligned with the modelled dynamics, a linear ozone scheme may not be applicable for a wide range of climatological conditions. An alternative approach to represent atmospheric chemistry in climate models which can cope with non-linearities in ozone chemistry and is applicable to a wide range of climatic states is the Semi-empirical Weighted Iterative Fit Technique (SWIFT) that is driven by reanalysis data and has been validated against observational satellite data and runs of a full Chemistry and Transport Model. SWIFT has been implemented into the ECHAM/MESSy (EMAC) chemistry climate model that uses a modular approach to climate modelling where individual model components can be switched on and off. When using SWIFT in EMAC, there are several possibilities to represent the effect of transport inside the polar vortex: the semi-Lagrangian transport scheme of EMAC and a transport parameterisation that can be useful when using SWIFT in models not having transport of their own. Here, we present results of equivalent simulations with different handling of transport, compare with EMAC simulations with full interactive chemistry and evaluate the results with observations.

A model for straight and helical solar jets: II. Parametric study of the plasma beta.

PubMed

Pariat, E; Dalmasse, K; DeVore, C R; Antiochos, S K; Karpen, J T

2016-12-01

Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere. Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e.g., in the vicinity of active regions as well as in coronal holes, and at various scales, from small photospheric spicules to large coronal jets. In all these events, signatures of helical structure and/or twisting/rotating motions are regularly observed. The present study aims to establish that a single model can generally reproduce the observed properties of these jet-like events. In this study, using our state-of-the-art numerical solver ARMS, we present a parametric study of a numerical tridimensional magnetohydrodynamic (MHD) model of solar jet-like events. Within the MHD paradigm, we study the impact of varying the atmospheric plasma β on the generation and properties of solar-like jets. The parametric study validates our model of jets for plasma β ranging from 10 -3 to 1, typical of the different layers and magnetic environments of the solar atmosphere. Our model of jets can robustly explain the generation of helical solar jet-like events at various β ≤ 1. This study introduces the new original result that the plasma β modifies the morphology of the helical jet, explaining the different observed shapes of jets at different scales and in different layers of the solar atmosphere. Our results allow us to understand the energisation, triggering, and driving processes of jet-like events. Our model allows us to make predictions of the impulsiveness and energetics of jets as determined by the surrounding environment, as well as the morphological properties of the resulting jets.

Extracting Urban Morphology for Atmospheric Modeling from Multispectral and SAR Satellite Imagery

NASA Astrophysics Data System (ADS)

Wittke, S.; Karila, K.; Puttonen, E.; Hellsten, A.; Auvinen, M.; Karjalainen, M.

2017-05-01

This paper presents an approach designed to derive an urban morphology map from satellite data while aiming to minimize the cost of data and user interference. The approach will help to provide updates to the current morphological databases around the world. The proposed urban morphology maps consist of two layers: 1) Digital Elevation Model (DEM) and 2) land cover map. Sentinel-2 data was used to create a land cover map, which was realized through image classification using optical range indices calculated from image data. For the purpose of atmospheric modeling, the most important classes are water and vegetation areas. The rest of the area includes bare soil and built-up areas among others, and they were merged into one class in the end. The classification result was validated with ground truth data collected both from field measurements and aerial imagery. The overall classification accuracy for the three classes is 91 %. TanDEM-X data was processed into two DEMs with different grid sizes using interferometric SAR processing. The resulting DEM has a RMSE of 3.2 meters compared to a high resolution DEM, which was estimated through 20 control points in flat areas. Comparing the derived DEM with the ground truth DEM from airborne LIDAR data, it can be seen that the street canyons, that are of high importance for urban atmospheric modeling are not detectable in the TanDEM-X DEM. However, the derived DEM is suitable for a class of urban atmospheric models. Based on the numerical modeling needs for regional atmospheric pollutant dispersion studies, the generated files enable the extraction of relevant parametrizations, such as Urban Canopy Parameters (UCP).

Simulation of Asian monsoon seasonal variations with climate model R42L9/LASG

NASA Astrophysics Data System (ADS)

Wang, Zaizhi; Wu, Guoxiong; Wu, Tongwen; Yu, Rucong

2004-12-01

The seasonal variations of the Asian monsoon were explored by applying the atmospheric general circulation model R42L9 that was developed recently at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences (LASG/IAP/CAS). The 20-yr (1979 1998) simulation was done using the prescribed 20-yr monthly SST and sea-ice data as required by Atmospheric Model Intercomparison Project (AMIP) II in the model. The monthly precipitation and monsoon circulations were analyzed and compared with the observations to validate the model’s performance in simulating the climatological mean and seasonal variations of the Asian monsoon. The results show that the model can capture the main features of the spatial distribution and the temporal evolution of precipitation in the Indian and East Asian monsoon areas. The model also reproduced the basic patterns of monsoon circulation. However, some biases exist in this model. The simulation of the heating over the Tibetan Plateau in summer was too strong. The overestimated heating caused a stronger East Asian monsoon and a weaker Indian monsoon than the observations. In the circulation fields, the South Asia high was stronger and located over the Tibetan Plateau. The western Pacific subtropical high was extended westward, which is in accordance with the observational results when the heating over the Tibetan Plateau is stronger. Consequently, the simulated rainfall around this area and in northwest China was heavier than in observations, but in the Indian monsoon area and west Pacific the rainfall was somewhat deficient.

Novel formulation of the ℳ model through the Generalized-K distribution for atmospheric optical channels.

PubMed

Garrido-Balsells, José María; Jurado-Navas, Antonio; Paris, José Francisco; Castillo-Vazquez, Miguel; Puerta-Notario, Antonio

2015-03-09

In this paper, a novel and deeper physical interpretation on the recently published Málaga or ℳ statistical distribution is provided. This distribution, which is having a wide acceptance by the scientific community, models the optical irradiance scintillation induced by the atmospheric turbulence. Here, the analytical expressions previously published are modified in order to express them by a mixture of the known Generalized-K and discrete Binomial and Negative Binomial distributions. In particular, the probability density function (pdf) of the ℳ model is now obtained as a linear combination of these Generalized-K pdf, in which the coefficients depend directly on the parameters of the ℳ distribution. In this way, the Málaga model can be physically interpreted as a superposition of different optical sub-channels each of them described by the corresponding Generalized-K fading model and weighted by the ℳ dependent coefficients. The expressions here proposed are simpler than the equations of the original ℳ model and are validated by means of numerical simulations by generating ℳ -distributed random sequences and their associated histogram. This novel interpretation of the Málaga statistical distribution provides a valuable tool for analyzing the performance of atmospheric optical channels for every turbulence condition.

Atmospheric Composition Change: Climate-Chemistry Interactions

NASA Technical Reports Server (NTRS)

Isaksen, I.S.A.; Granier, C.; Myhre, G.; Bernsten, T. K.; Dalsoren, S. B.; Gauss, S.; Klimont, Z.; Benestad, R.; Bousquet, P.; Collins, W.;

Validation of a continuous flow method for the determination of soluble iron in atmospheric dust and volcanic ash.

PubMed

Simonella, Lucio E; Gaiero, Diego M; Palomeque, Miriam E

2014-10-01

Iron is an essential micronutrient for phytoplankton growth and is supplied to the remote areas of the ocean mainly through atmospheric dust/ash. The amount of soluble Fe in dust/ash is a major source of uncertainty in modeling-Fe dissolution and deposition to the surface ocean. Currently in the literature, there exist almost as many different methods to estimate fractional solubility as researchers in the field, making it difficult to compare results between research groups. Also, an important constraint to evaluate Fe solubility in atmospheric dust is the limited mass of sample which is usually only available in micrograms to milligrams amounts. A continuous flow (CF) method that can be run with low mass of sediments (<10mg) was tested against a standard method which require about 1g of sediments (BCR of the European Union). For validation of the CF experiment, we run both methods using South American surface sediment and deposited volcanic ash. Both materials tested are easy eroded by wind and are representative of atmospheric dust/ash exported from this region. The uncertainty of the CF method was obtained from seven replicates of one surface sediment sample, and shows very good reproducibility. The replication was conducted on different days in a span of two years and ranged between 8 and 22% (i.e., the uncertainty for the standard method was 6-19%). Compared to other standardized methods, the CF method allows studies of dissolution kinetic of metals and consumes less reagents and time (<3h). The method validated here is suggested to be used as a standardized method for Fe solubility studies on dust/ash. Copyright © 2014 Elsevier B.V. All rights reserved.

Preliminary Structural Sensitivity Study of Hypersonic Inflatable Aerodynamic Decelerator Using Probabilistic Methods

NASA Technical Reports Server (NTRS)

Lyle, Karen H.

2014-01-01

Acceptance of new spacecraft structural architectures and concepts requires validated design methods to minimize the expense involved with technology validation via flighttesting. This paper explores the implementation of probabilistic methods in the sensitivity analysis of the structural response of a Hypersonic Inflatable Aerodynamic Decelerator (HIAD). HIAD architectures are attractive for spacecraft deceleration because they are lightweight, store compactly, and utilize the atmosphere to decelerate a spacecraft during re-entry. However, designers are hesitant to include these inflatable approaches for large payloads or spacecraft because of the lack of flight validation. In the example presented here, the structural parameters of an existing HIAD model have been varied to illustrate the design approach utilizing uncertainty-based methods. Surrogate models have been used to reduce computational expense several orders of magnitude. The suitability of the design is based on assessing variation in the resulting cone angle. The acceptable cone angle variation would rely on the aerodynamic requirements.

Advances in air quality prediction with the use of integrated systems

NASA Astrophysics Data System (ADS)

Dragani, R.; Benedetti, A.; Engelen, R. J.; Peuch, V. H.

2017-12-01

Recent years have seen the rise of global operational atmospheric composition forecasting systems for several applications including climate monitoring, provision of boundary conditions for regional air quality forecasting, energy sector applications, to mention a few. Typically, global forecasts are provided in the medium-range up to five days ahead and are initialized with an analysis based on satellite data. In this work we present the latest advances in data assimilation using the ECMWF's 4D-Var system extended to atmospheric composition which is currently operational under the Copernicus Atmosphere Monitoring Service of the European Commission. The service is based on acquisition of all relevant data available in near-real-time, the processing of these datasets in the assimilation and the subsequent dissemination of global forecasts at ECMWF. The global forecasts are used by the CAMS regional models as boundary conditions for the European forecasts based on a multi-model ensemble. The global forecasts are also used to provide boundary conditions for other parts of the world (e.g., China) and are freely available to all interested entities. Some of the regional models also perform assimilation of satellite and ground-based observations. All products are assessed, validated and made publicly available on https://atmosphere.copernicus.eu/.

Assessment of environments for Mars Science Laboratory entry, descent, and surface operations

USGS Publications Warehouse

Vasavada, Ashwin R.; Chen, Allen; Barnes, Jeffrey R.; Burkhart, P. Daniel; Cantor, Bruce A.; Dwyer-Cianciolo, Alicia M.; Fergason, Robini L.; Hinson, David P.; Justh, Hilary L.; Kass, David M.; Lewis, Stephen R.; Mischna, Michael A.; Murphy, James R.; Rafkin, Scot C.R.; Tyler, Daniel; Withers, Paul G.

2012-01-01

The Mars Science Laboratory mission aims to land a car-sized rover on Mars' surface and operate it for at least one Mars year in order to assess whether its field area was ever capable of supporting microbial life. Here we describe the approach used to identify, characterize, and assess environmental risks to the landing and rover surface operations. Novel entry, descent, and landing approaches will be used to accurately deliver the 900-kg rover, including the ability to sense and "fly out" deviations from a best-estimate atmospheric state. A joint engineering and science team developed methods to estimate the range of potential atmospheric states at the time of arrival and to quantitatively assess the spacecraft's performance and risk given its particular sensitivities to atmospheric conditions. Numerical models are used to calculate the atmospheric parameters, with observations used to define model cases, tune model parameters, and validate results. This joint program has resulted in a spacecraft capable of accessing, with minimal risk, the four finalist sites chosen for their scientific merit. The capability to operate the landed rover over the latitude range of candidate landing sites, and for all seasons, was verified against an analysis of surface environmental conditions described here. These results, from orbital and model data sets, also drive engineering simulations of the rover's thermal state that are used to plan surface operations.

Radiative flux opens new window on climate research

NASA Technical Reports Server (NTRS)

Pinker, R. T.; Laszlo, I.; Whitlock, C. H.; Charlock, T. P.

1995-01-01

For several decades, global satellite observations have been made of the rate at which electromagnetic energy (radiative flux) is emerging from the top of the atmosphere of our planet in the spectral range of about 0.2-50.0 microns. At the same time, models have been developed to infer the radiative flux at the surface from the values observed by the satellites at the upper boundary. The balance of incoming and outgoing radiative flux (radiation budget) at both boundaries, determines the net gain or loss of the radiative energy within an atmospheric column. Climate researchers can use the radiative flux as a tool to validate climate models, separate the radiative impact of clouds from surface and atmosphere contributions, and to understand the global hydrological cycle. When applied to physical processes occurring at the surface, information on the radiative flux has the potential to substantially advance our understanding of the transport of heat, moisture, and momentum across the surface/atmosphere interface. Geophysicists of many disciplines stand to benefit from efforts to improve the use of this latter untapped resource. Oceanographers can improve the representation of the selective absorption of radiation in the oceans; biologists and ecologists can improve their models for carbon dioxide exchange and biological heating in oceans; agronomists can model more realistically biomass and crop yields; and environmentalists can obtain better assessment of natural resources of radiation.

Improved Atmospheric Correction for AVIRIS Spectra from Inland Waters

NASA Technical Reports Server (NTRS)

Gastil, Mary; Melack, John M.

1998-01-01

Remote sensing reflectance (Rrs) cannot be measured directly. Comparison of Rrs calculated from field measurements to Rrs calculated from AVIRIS spectra and the atmospheric radiative transfer model modtran provides a measure of the accuracy of our method. That and other comparisons are presented here as a validation of a method of retrieving Rrs from inland waters from AVIRIS radiance. The method of collecting field measurements for Rrs is described in Hamilton, 1993. Retrieval of Rrs from AVIRIS using modtran was developed from Carder, 1993. AVIRIS radiance is reduced by the path radiance modeled by modtran and divided by one-way transmission. Skylight, modeled by modtran, specularly reflected from the lake surface, is then subtracted from this radiance, leaving only that radiance which has come from under water. This water-leaving radiance is then normalized by the downwelling irradiance incident at the surface as modeled by modtran. Our improved retrieval of Rrs has allowed us to fit a single curve to a set of 134 pairs of AVIRIS Rrs and measured chlorophyll gathered on eight experiments at Mono Lake. Previously, spectra from different surveys varied more due to lingering atmospheric effects and/or radiometric calibration imprecision than they varied due to chlorophyll.

A COMPREHENSIVE ANALYSIS OF CHLORINE TRANSPORT AND FATE FOLLOWING A LARGE ENVIRONMENTAL RELEASE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buckley, R.; Hunter, C.; Werth, D.

2011-05-10

A train derailment occurred in Graniteville, South Carolina during the early morning of January 6, 2005, and resulted in the release of a large amount of cryogenic pressurized liquid chlorine to the environment in a short time period. A comprehensive evaluation of the transport and fate of the released chlorine was performed, accounting for dilution, diffusion, transport and deposition into the local environment. This involved the characterization of a three-phased chlorine release, a detailed determination of local atmospheric mechanisms acting on the released chlorine, the establishment of atmospheric-hydrological physical exchange mechanisms, and aquatic dilution and mixing. This presentation will providemore » an overview of the models used in determining the total air-to-water mass transfer estimated to have occurred as a result of the roughly 60 tons of chlorine released into the atmosphere from the train derailment. The assumptions used in the modeling effort will be addressed, along with a comparison with available observational data to validate the model results. Overall, model-estimated chlorine concentrations in the airborne plume compare well with human and animal exposure data collected in the days after the derailment.« less

Impact of lakes and wetlands on present and future boreal climate

NASA Astrophysics Data System (ADS)

Poutou, E.; Krinner, G.; Genthon, C.

2002-12-01

Impact of lakes and wetlands on present and future boreal climate The role of lakes and wetlands in present-day high latitude climate is quantified using a general circulation model of the atmosphere. The atmospheric model includes a lake module which is presented and validated. Seasonal and spatial wetland distribution is calculated as a function of the hydrological budget of the wetlands themselves and of continental soil whose runoff feeds them. Wetland extent is simulated and discussed both in simulations forced by observed climate and in general circulation model simulations. In off-line simulations, forced by ECMWF reanalyses, the lake model simulates correctly observed lake ice durations, while the wetland extent is somewhat underestimated in the boreal regions. Coupled to the general circulation model, the lake model yields satisfying ice durations, although the climate model biases have impacts on the modeled lake ice conditions. Boreal wetland extents are overestimated in the general circulation model as simulated precipitation is too high. The impact of inundated surfaces on the simulated climate is strongest in summer when these surfaces are ice-free. Wetlands seem to play a more important role than lakes in cooling the boreal regions in summer and in humidifying the atmosphere. The role of lakes and wetlands in future climate change is evaluated by analyzing simulations of present and future climate with and without prescribed inland water bodies.

In-flight radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

NASA Technical Reports Server (NTRS)

Conel, James E.; Green, Robert O.; Alley, Ronald E.; Bruegge, Carol J.; Carrere, Veronique; Margolis, Jack S.; Vane, Gregg; Chrien, Thomas G.; Slater, Philip N.; Biggard, Stuart F.

1988-01-01

A reflectance-based method was used to provide an analysis of the in-flight radiometric performance of AVIRIS. Field spectral reflectance measurements of the surface and extinction measurements of the atmosphere using solar radiation were used as input to atmospheric radiative transfer calculations. Five separate codes were used in the analysis. Four include multiple scattering, and the computed radiances from these for flight conditions were in good agreement. Code-generated radiances were compared with AVIRIS-predicted radiances based on two laboratory calibrations (pre- and post-season of flight) for a uniform highly reflecting natural dry lake target. For one spectrometer (C), the pre- and post-season calibration factors were found to give identical results, and to be in agreement with the atmospheric models that include multiple scattering. This positive result validates the field and laboratory calibration technique. Results for the other spectrometers (A, B and D) were widely at variance with the models no matter which calibration factors were used. Potential causes of these discrepancies are discussed.

Ultraspectral sounding retrieval error budget and estimation

NASA Astrophysics Data System (ADS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, Larrabee L.; Yang, Ping

2011-11-01

The ultraspectral infrared radiances obtained from satellite observations provide atmospheric, surface, and/or cloud information. The intent of the measurement of the thermodynamic state is the initialization of weather and climate models. Great effort has been given to retrieving and validating these atmospheric, surface, and/or cloud properties. Error Consistency Analysis Scheme (ECAS), through fast radiative transfer model (RTM) forward and inverse calculations, has been developed to estimate the error budget in terms of absolute and standard deviation of differences in both spectral radiance and retrieved geophysical parameter domains. The retrieval error is assessed through ECAS without assistance of other independent measurements such as radiosonde data. ECAS re-evaluates instrument random noise, and establishes the link between radiometric accuracy and retrieved geophysical parameter accuracy. ECAS can be applied to measurements of any ultraspectral instrument and any retrieval scheme with associated RTM. In this paper, ECAS is described and demonstration is made with the measurements of the METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI).

Ultraspectral Sounding Retrieval Error Budget and Estimation

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

2011-01-01

The ultraspectral infrared radiances obtained from satellite observations provide atmospheric, surface, and/or cloud information. The intent of the measurement of the thermodynamic state is the initialization of weather and climate models. Great effort has been given to retrieving and validating these atmospheric, surface, and/or cloud properties. Error Consistency Analysis Scheme (ECAS), through fast radiative transfer model (RTM) forward and inverse calculations, has been developed to estimate the error budget in terms of absolute and standard deviation of differences in both spectral radiance and retrieved geophysical parameter domains. The retrieval error is assessed through ECAS without assistance of other independent measurements such as radiosonde data. ECAS re-evaluates instrument random noise, and establishes the link between radiometric accuracy and retrieved geophysical parameter accuracy. ECAS can be applied to measurements of any ultraspectral instrument and any retrieval scheme with associated RTM. In this paper, ECAS is described and demonstration is made with the measurements of the METOP-A satellite Infrared Atmospheric Sounding Interferometer (IASI)..

Modeling climatic effects of anthropogenic CO2 emissions: Unknowns and uncertainties

NASA Astrophysics Data System (ADS)

Soon, W.; Baliunas, S.; Idso, S.; Kondratyev, K. Ya.; Posmentier, E. S.

2001-12-01

A likelihood of disastrous global environmental consequences has been surmised as a result of projected increases in anthropogenic greenhouse gas emissions. These estimates are based on computer climate modeling, a branch of science still in its infancy despite recent, substantial strides in knowledge. Because the expected anthropogenic climate forcings are relatively small compared to other background and forcing factors (internal and external), the credibility of the modeled global and regional responses rests on the validity of the models. We focus on this important question of climate model validation. Specifically, we review common deficiencies in general circulation model calculations of atmospheric temperature, surface temperature, precipitation and their spatial and temporal variability. These deficiencies arise from complex problems associated with parameterization of multiply-interacting climate components, forcings and feedbacks, involving especially clouds and oceans. We also review examples of expected climatic impacts from anthropogenic CO2 forcing. Given the host of uncertainties and unknowns in the difficult but important task of climate modeling, the unique attribution of observed current climate change to increased atmospheric CO2 concentration, including the relatively well-observed latest 20 years, is not possible. We further conclude that the incautious use of GCMs to make future climate projections from incomplete or unknown forcing scenarios is antithetical to the intrinsically heuristic value of models. Such uncritical application of climate models has led to the commonly-held but erroneous impression that modeling has proven or substantiated the hypothesis that CO2 added to the air has caused or will cause significant global warming. An assessment of the positive skills of GCMs and their use in suggesting a discernible human influence on global climate can be found in the joint World Meteorological Organisation and United Nations Environmental Programme's Intergovernmental Panel on Climate Change, IPCC, reports (1990, 1995 and 2001). Our review highlights only the enormous scientific difficulties facing the calculation of climatic effects of added atmospheric CO2 in a GCM. The purpose of such a limited review of the deficiencies of climate model physics and the use of GCMs is to illuminate areas for improvement. Our review does not disprove a significant anthropogenic influence on global climate.

Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background.

PubMed

Nikolova, Irina; MacKenzie, A Rob; Cai, Xiaoming; Alam, Mohammed S; Harrison, Roy M

2016-07-18

We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A two-stage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which there exists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the model can reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail the size resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the chemical composition of nucleation-mode particles from diesel engine exhaust is needed to predict both their atmospheric behaviour and their implications for human health.

Numerical simulations of LNG vapor dispersion in Brayton Fire Training Field tests with ANSYS CFX.

PubMed

Qi, Ruifeng; Ng, Dedy; Cormier, Benjamin R; Mannan, M Sam

2010-11-15

Federal safety regulations require the use of validated consequence models to determine the vapor cloud dispersion exclusion zones for accidental liquefied natural gas (LNG) releases. One tool that is being developed in industry for exclusion zone determination and LNG vapor dispersion modeling is computational fluid dynamics (CFD). This paper uses the ANSYS CFX CFD code to model LNG vapor dispersion in the atmosphere. Discussed are important parameters that are essential inputs to the ANSYS CFX simulations, including the atmospheric conditions, LNG evaporation rate and pool area, turbulence in the source term, ground surface temperature and roughness height, and effects of obstacles. A sensitivity analysis was conducted to illustrate uncertainties in the simulation results arising from the mesh size and source term turbulence intensity. In addition, a set of medium-scale LNG spill tests were performed at the Brayton Fire Training Field to collect data for validating the ANSYS CFX prediction results. A comparison of test data with simulation results demonstrated that CFX was able to describe the dense gas behavior of LNG vapor cloud, and its prediction results of downwind gas concentrations close to ground level were in approximate agreement with the test data. Copyright © 2010 Elsevier B.V. All rights reserved.

Modeling study of biomass burning plumes and their impact on urban air quality; a case study of Santiago de Chile

NASA Astrophysics Data System (ADS)

Cuchiara, Gustavo C.; Rappenglück, Bernhard; Angelica Rubio, Maria; Lissi, Eduardo; Gramsch, Ernesto; Garreaud, Rene D.

2017-04-01

Wildfires are a significant direct source of atmospheric pollutants; on a global scale biomass burning is believed to be the largest source of primary fine particles in the atmosphere and the second largest source of trace gases after anthropogenic emission sources. During the summer of 2014, an intense forest and dry pasture wildfire occurred nearby the city of Santiago de Chile. The biomass-burning plume was transported towards the metropolitan area of Santiago and exacerbated the air quality in this region. In this study, we investigated this wildfire event using a forward plume-rise and a chemistry (WRF/Chem) simulation. These data sets provided an opportunity to validate a regional air-quality simulation over Santiago, and a unique case to assess the performance of biomass burning plume modeling in complex topography and validated against an established air quality network. The results from both meteorological and air quality models provide insights about the transport of biomass-burning plumes from the wildfire region towards the metropolitan region of Santiago de Chile. We studied a seven-day period between January 01-07, 2014, and the impact of biomass burning plume emissions estimated by Fire Inventory from NCAR version 1 (FINNv1) on the air quality of Santiago de Chile.

A method to estimate the neutral atmospheric density near the ionospheric main peak of Mars

NASA Astrophysics Data System (ADS)

Zou, Hong; Ye, Yu Guang; Wang, Jin Song; Nielsen, Erling; Cui, Jun; Wang, Xiao Dong

2016-04-01

A method to estimate the neutral atmospheric density near the ionospheric main peak of Mars is introduced in this study. The neutral densities at 130 km can be derived from the ionospheric and atmospheric measurements of the Radio Science experiment on board Mars Global Surveyor (MGS). The derived neutral densities cover a large longitude range in northern high latitudes from summer to late autumn during 3 Martian years, which fills the gap of the previous observations for the upper atmosphere of Mars. The simulations of the Laboratoire de Météorologie Dynamique Mars global circulation model can be corrected with a simple linear equation to fit the neutral densities derived from the first MGS/RS (Radio Science) data sets (EDS1). The corrected simulations with the same correction parameters as for EDS1 match the derived neutral densities from two other MGS/RS data sets (EDS2 and EDS3) very well. The derived neutral density from EDS3 shows a dust storm effect, which is in accord with the Mars Express (MEX) Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars measurement. The neutral density derived from the MGS/RS measurements can be used to validate the Martian atmospheric models. The method presented in this study can be applied to other radio occultation measurements, such as the result of the Radio Science experiment on board MEX.

Current status of validating operational model forecasts at the DWD site Lindenberg

NASA Astrophysics Data System (ADS)

Beyrich, F.; Heret, C.; Vogel, G.

2009-09-01

Based on long experience in the measurement of atmospheric boundary layer parameters, the Meteorological Observatory Lindenberg / Richard - Aßmann-Observatory is well qualified to validate operational NWP results for this location. The validation activities cover a large range of time periods from single days or months up to several years and include much more quantities than generally used in areal verification techniques. They mainly focus on land surface and boundary layer processes which play an important role in the atmospheric forc-ing from the surface. Versatility and continuity of the database enable a comprehensive evaluation of the model behaviour under different meteorological conditions in order to esti-mate the accuracy of the physical parameterisations and to detect possible deficiencies in the predicted processes. The measurements from the boundary layer field site Falkenberg serve as reference data for various types of validation studies: 1. The operational boundary-layer measurements are used to identify and to document weather situations with large forecast errors which can then be analysed in more de-tail. Results from a case study will be presented where model deficiencies in the cor-rect simulation of the diurnal evolution of near-surface temperature under winter con-ditions over a closed snow cover where diagnosed. 2. Due to the synopsis of the boundary layer quantities based on monthly averaged di-urnal cycles systematic model deficiencies can be detected more clearly. Some dis-tinctive features found in the annual cycle (e.g. near-surface temperatures, turbulent heat fluxes and soil moisture) will be outlined. Further aspects are their different ap-pearance in the COSMO-EU and COSMO-DE models as well as the effects of start-ing time (00 or 12 UTC) on the prediction accuracy. 3. The evaluation of the model behaviour over several years provides additional insight into the impact of changes in the physical parameterisations, data assimilation or nu-merics on the meteorological quantities. The temporal development of the error char-acteristics of some near-surface weather parameters (temperature, dewpoint tem-perature, wind velocity) and of the energy fluxes at the surface will be discussed.

Atmospheric Correction at AERONET Locations: A New Science and Validation Data Set

NASA Technical Reports Server (NTRS)

Wang, Yujie; Lyapustin, Alexei; Privette, Jeffery L.; Morisette, Jeffery T.; Holben, Brent

2008-01-01

This paper describes an AERONET-based Surface Reflectance Validation Network (ASRVN) and its dataset of spectral surface bidirectional reflectance and albedo based on MODIS TERRA and AQUA data. The ASRVN is an operational data collection and processing system. It receives 50x50 square kilometer subsets of MODIS L1B data from MODAPS and AERONET aerosol and water vapor information. Then it performs an accurate atmospheric correction for about 100 AERONET sites based on accurate radiative transfer theory with high quality control of the input data. The ASRVN processing software consists of L1B data gridding algorithm, a new cloud mask algorithm based on a time series analysis, and an atmospheric correction algorithm. The atmospheric correction is achieved by fitting the MODIS top of atmosphere measurements, accumulated for 16-day interval, with theoretical reflectance parameterized in terms of coefficients of the LSRT BRF model. The ASRVN takes several steps to ensure high quality of results: 1) cloud mask algorithm filters opaque clouds; 2) an aerosol filter has been developed to filter residual semi-transparent and sub-pixel clouds, as well as cases with high inhomogeneity of aerosols in the processing area; 3) imposing requirement of consistency of the new solution with previously retrieved BRF and albedo; 4) rapid adjustment of the 16-day retrieval to the surface changes using the last day of measurements; and 5) development of seasonal back-up spectral BRF database to increase data coverage. The ASRVN provides a gapless or near-gapless coverage for the processing area. The gaps, caused by clouds, are filled most naturally with the latest solution for a given pixels. The ASRVN products include three parameters of LSRT model (k(sup L), k(sup G), k(sup V)), surface albedo, NBRF (a normalized BRF computed for a standard viewing geometry, VZA=0 deg., SZA=45 deg.), and IBRF (instantaneous, or one angle, BRF value derived from the last day of MODIS measurement for specific viewing geometry) for MODIS 500m bands 1-7. The results are produced daily at resolution of 1 km in gridded format. We also provide cloud mask, quality flag and a browse bitmap image. The new dataset can be used for a wide range of applications including validation analysis and science research.

High-Speed Research: Sonic Boom, Volume 1

NASA Technical Reports Server (NTRS)

Edwards, Thomas A. (Editor)

1994-01-01

The second High-Speed Research Program Sonic Boom Workshop was held at NASA Ames Research Center May 12-14, 1993. The workshop was organized into three sessions dealing with atmospheric propagation, acceptability, and configuration design. Volume 1 includes papers on atmospheric propagation and acceptability studies. Significant progress is noted in these areas in the time since the previous workshop a year earlier. In particular, several papers demonstrate an improved capability to model the effect of atmospheric turbulence on sonic booms. This is a key issue in determining the stability and acceptability of shaped sonic booms. In the area of acceptability, the PLdB metric has withstood considerable scrutiny and is validated as a loudness metric for a wide variety of sonic boom shapes. The differential loudness of asymmetric sonic booms is better understood, too.

Validation of scintillometer measurements over a heterogeneous landscape: The LITFASS-2009 Experiment

NASA Astrophysics Data System (ADS)

Beyrich, F.; Bange, J.; Hartogensis, O.; Raasch, S.

2009-09-01

The turbulent exchange of heat and water vapour are essential land surface - atmosphere interaction processes in the local, regional and global energy and water cycles. Scintillometry can be considered as the only technique presently available for the quasi-operational experimental determination of area-averaged turbulent fluxes needed to validate the fluxes simulated by regional atmospheric models or derived from satellite images at a horizontal scale of a few kilometres. While scintillometry has found increasing application over the last years, some fundamental issues related to its use still need further investigation. In particular, no studies are known so far to reproduce the path-averaged structure parameters measured by scintillometers by independent measurements or modelling techniques. The LITFASS-2009 field experiment has been performed in the area around the Meteorological Observatory Lindenberg / Richard-Aßmann-Observatory in Germany during summer 2009. It was designed to investigate the spatial (horizontal and vertical) and temporal variability of structure parameters (underlying the scintillometer principle) over moderately heterogeneous terrain. The experiment essentially relied on a coupling of eddy-covariance measurements, scintillometry and airborne measurements with an unmanned autonomous aircraft able to strictly fly along the scintillometer path. Data interpretation will be supported by numerical modelling using a large-eddy simulation (LES) model. The paper will describe the design of the experiment. First preliminary results from the measurements will be presented.

Spectroscopic analysis of Cepheid variables with 2D radiation-hydrodynamic simulations

NASA Astrophysics Data System (ADS)

Vasilyev, Valeriy

2018-06-01

The analysis of chemical enrichment history of dwarf galaxies allows to derive constraints on their formation and evolution. In this context, Cepheids play a very important role, as these periodically variable stars provide a means to obtain accurate distances. Besides, chemical composition of Cepheids can provide a strong constraint on the chemical evolution of the system. Standard spectroscopic analysis of Cepheids is based on using one-dimensional (1D) hydrostatic model atmospheres, with convection parametrised using the mixing-length theory. However, this quasi-static approach has theoretically not been validated. In my talk, I will discuss the validity of the quasi-static approximation in spectroscopy of short-periodic Cepheids. I will show the results obtained using a 2D time-dependent envelope model of a pulsating star computed with the radiation-hydrodynamics code CO5BOLD. I will then describe the impact of new models on the spectroscopic diagnostic of the effective temperature, surface gravity, microturbulent velocity, and metallicity. One of the interesting findings of my work is that 1D model atmospheres provide unbiased estimates of stellar parameters and abundances of Cepheid variables for certain phases of their pulsations. Convective inhomogeneities, however, also introduce biases. I will then discuss how these results can be used in a wider parameter space of pulsating stars and present an outlook for the future studies.

Validation of the ENVISAT atmospheric chemistry instruments

NASA Astrophysics Data System (ADS)

Snoeij, P.; Koopman, R.; Attema, E.; Zehner, C.; Wursteisen, P.; Dehn, A.; de Laurentius, M.; Frerick, J.; Mantovani, R.; Saavedra de Miguel, L.

Three atmospheric-chemistry sensors form part of the ENVISAT payload that has been placed into orbit in March 2002. This paper presents the ENVISAT mission status and data policy, and reviews the end-to-end performance of the GOMOS, MIPAS and SCIAMACHY observation systems and will discuss the validation aspects of these instruments. In particular, for each instrument, the review addresses mission planning, in-orbit performance, calibration, data processor algorithms and configuration, reprocessing strategy, and product quality control assessment. An important part of the quality assessment is the Geophysical Validation. At the ACVT Validation workshop held in Frascati, Italy, from 3-7 May 2004, scientists and engineers presented analyses of the exhaustive series of tests that have been run on each of ENVISAT atmospheric chemistry sensors since the spacecraft was launched in March 2002. On the basis of workshop results it was decided that most of the data products provided by the ENVISAT atmospheric chemistry instruments are ready for operational delivery. Although the main validation phase for the atmospheric instruments of ENVISAT will be completed soon, ongoing validation products will continue throughout the lifetime of the ENVISAT mission. The long-term validation phase will: Provide assurance of data quality and accuracy for applications such as climate change research Investigate the fully representative range of geophysical conditions Investigate the fully representative range of seasonal cycles Perform long term monitoring for instrumental drifts and other artefacts Validate new products. This paper will also discuss the general status of the validation activities for GOMOS, MIPAS and SCIAMACHY. The main and long-term geophysical validation programme will be presented. The flight and ground-segment planning, configuration and performance characterization will be discussed. The evolution of each of the observation systems has been distinct during the mission history: the GOMOS instrument operation has undergone an important change, and its processing chain is subject of two upgrades. For MIPAS intervention on one of the on-board subsystems has proven necessary, and an important data processing improvement cycle has been completed through reconfiguration of the processing chain. SCIAMACHY operations have required only minor interventions, and the presentation will focus on the processing chain evolution.

Analyzing coastal turbidity under complex terrestrial loads characterized by a 'stress connectivity matrix' with an atmosphere-watershed-coastal ocean coupled model

NASA Astrophysics Data System (ADS)

Yamamoto, Takahiro; Nadaoka, Kazuo

2018-04-01

Atmospheric, watershed and coastal ocean models were integrated to provide a holistic analysis approach for coastal ocean simulation. The coupled model was applied to coastal ocean in the Philippines where terrestrial sediment loads provided from several adjacent watersheds play a major role in influencing coastal turbidity and are partly responsible for the coastal ecosystem degradation. The coupled model was validated using weather and hydrologic measurement to examine its potential applicability. The results revealed that the coastal water quality may be governed by the loads not only from the adjacent watershed but also from the distant watershed via coastal currents. This important feature of the multiple linkages can be quantitatively characterized by a "stress connectivity matrix", which indicates the complex underlying structure of environmental stresses in coastal ocean. The multiple stress connectivity concept shows the potential advantage of the integrated modelling approach for coastal ocean assessment, which may also serve for compensating the lack of measured data especially in tropical basins.

Changes in the flood frequency in the Mahanadi basin under observed and projected future climate

NASA Astrophysics Data System (ADS)

Modi, P. A.; Lakshmi, V.; Mishra, V.

2017-12-01

The Mahanadi river basin is vulnerable to multiple types of extreme events due to its topography and river networks. These extreme events are not efficiently captured by the current LSMs partly due to lack of spatial hydrological data and uncertainty in the models. This study compares and evaluates the hydrologic simulations of the recently developed community Noah model with multi-parameterization options which is an upgradation of baseline Noah LSM. The model is calibrated and validated for the Mahanadi river basin and is driven by major atmospheric forcing from the Indian Meteorological Department (IMD), Global Precipitation Measurement (GPM), Tropical rainfall Measurement Mission (TRMM) and Multi-Source Weighted-Ensemble Precipitation (MSWEP designed for hydrological modeling) precipitation datasets along with some additional forcing derived from the VIC model at 0.25-degree spatial resolution. The Noah-MP LSM is calibrated using observed daily streamflow data from 1978-1989 (India-WRIS) at the gauge stations with least human interventions with a Nash Sutcliffe Efficiency higher than 0.60. Noah MP was calibrated using different schemes for runoff with variation in all parameters sensitive to surface and sub-surface runoff. Streamflow routing was performed using a stand-alone model (VIC model) to route daily model runoff at required gauge station. Surface runoff is mainly affected by the uncertainties in major atmospheric forcing and highly sensitive parameters pertaining to soil properties. Noah MP is validated using observed streamflow from 1975-2010 which indicates the consistency of streamflow with the historical observations (NSE>0.65) thus indicating an increase in probability of future flood events.

Chemiluminescence-based multivariate sensing of local equivalence ratios in premixed atmospheric methane-air flames

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripathi, Markandey M.; Krishnan, Sundar R.; Srinivasan, Kalyan K.

Chemiluminescence emissions from OH*, CH*, C2, and CO2 formed within the reaction zone of premixed flames depend upon the fuel-air equivalence ratio in the burning mixture. In the present paper, a new partial least square regression (PLS-R) based multivariate sensing methodology is investigated and compared with an OH*/CH* intensity ratio-based calibration model for sensing equivalence ratio in atmospheric methane-air premixed flames. Five replications of spectral data at nine different equivalence ratios ranging from 0.73 to 1.48 were used in the calibration of both models. During model development, the PLS-R model was initially validated with the calibration data set using themore » leave-one-out cross validation technique. Since the PLS-R model used the entire raw spectral intensities, it did not need the nonlinear background subtraction of CO2 emission that is required for typical OH*/CH* intensity ratio calibrations. An unbiased spectral data set (not used in the PLS-R model development), for 28 different equivalence ratio conditions ranging from 0.71 to 1.67, was used to predict equivalence ratios using the PLS-R and the intensity ratio calibration models. It was found that the equivalence ratios predicted with the PLS-R based multivariate calibration model matched the experimentally measured equivalence ratios within 7%; whereas, the OH*/CH* intensity ratio calibration grossly underpredicted equivalence ratios in comparison to measured equivalence ratios, especially under rich conditions ( > 1.2). The practical implications of the chemiluminescence-based multivariate equivalence ratio sensing methodology are also discussed.« less

Development of a methodology for probable maximum precipitation estimation over the American River watershed using the WRF model

NASA Astrophysics Data System (ADS)

Tan, Elcin

A new physically-based methodology for probable maximum precipitation (PMP) estimation is developed over the American River Watershed (ARW) using the Weather Research and Forecast (WRF-ARW) model. A persistent moisture flux convergence pattern, called Pineapple Express, is analyzed for 42 historical extreme precipitation events, and it is found that Pineapple Express causes extreme precipitation over the basin of interest. An average correlation between moisture flux convergence and maximum precipitation is estimated as 0.71 for 42 events. The performance of the WRF model is verified for precipitation by means of calibration and independent validation of the model. The calibration procedure is performed only for the first ranked flood event 1997 case, whereas the WRF model is validated for 42 historical cases. Three nested model domains are set up with horizontal resolutions of 27 km, 9 km, and 3 km over the basin of interest. As a result of Chi-square goodness-of-fit tests, the hypothesis that "the WRF model can be used in the determination of PMP over the ARW for both areal average and point estimates" is accepted at the 5% level of significance. The sensitivities of model physics options on precipitation are determined using 28 microphysics, atmospheric boundary layer, and cumulus parameterization schemes combinations. It is concluded that the best triplet option is Thompson microphysics, Grell 3D ensemble cumulus, and YSU boundary layer (TGY), based on 42 historical cases, and this TGY triplet is used for all analyses of this research. Four techniques are proposed to evaluate physically possible maximum precipitation using the WRF: 1. Perturbations of atmospheric conditions; 2. Shift in atmospheric conditions; 3. Replacement of atmospheric conditions among historical events; and 4. Thermodynamically possible worst-case scenario creation. Moreover, climate change effect on precipitation is discussed by emphasizing temperature increase in order to determine the physically possible upper limits of precipitation due to climate change. The simulation results indicate that the meridional shift in atmospheric conditions is the optimum method to determine maximum precipitation in consideration of cost and efficiency. Finally, exceedance probability analyses of the model results of 42 historical extreme precipitation events demonstrate that the 72-hr basin averaged probable maximum precipitation is 21.72 inches for the exceedance probability of 0.5 percent. On the other hand, the current operational PMP estimation for the American River Watershed is 28.57 inches as published in the hydrometeorological report no. 59 and a previous PMP value was 31.48 inches as published in the hydrometeorological report no. 36. According to the exceedance probability analyses of this proposed method, the exceedance probabilities of these two estimations correspond to 0.036 percent and 0.011 percent, respectively.

Wab-InSAR: a new wavelet based InSAR time series technique applied to volcanic and tectonic areas

NASA Astrophysics Data System (ADS)

Walter, T. R.; Shirzaei, M.; Nankali, H.; Roustaei, M.

2009-12-01

Modern geodetic techniques such as InSAR and GPS provide valuable observations of the deformation field. Because of the variety of environmental interferences (e.g., atmosphere, topography distortion) and incompleteness of the models (assumption of the linear model for deformation), those observations are usually tainted by various systematic and random errors. Therefore we develop and test new methods to identify and filter unwanted periodic or episodic artifacts to obtain accurate and precise deformation measurements. Here we present and implement a new wavelet based InSAR (Wab-InSAR) time series approach. Because wavelets are excellent tools for identifying hidden patterns and capturing transient signals, we utilize wavelet functions for reducing the effect of atmospheric delay and digital elevation model inaccuracies. Wab-InSAR is a model free technique, reducing digital elevation model errors in individual interferograms using a 2D spatial Legendre polynomial wavelet filter. Atmospheric delays are reduced using a 3D spatio-temporal wavelet transform algorithm and a novel technique for pixel selection. We apply Wab-InSAR to several targets, including volcano deformation processes at Hawaii Island, and mountain building processes in Iran. Both targets are chosen to investigate large and small amplitude signals, variable and complex topography and atmospheric effects. In this presentation we explain different steps of the technique, validate the results by comparison to other high resolution processing methods (GPS, PS-InSAR, SBAS) and discuss the geophysical results.

Comparisons Between Model Predictions and Spectral Measurements of Charged and Neutral Particles on the Martian Surface

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee Y.; Cucinotta, Francis A.; Zeitlin, Cary; Hassler, Donald M.; Ehresmann, Bent; Rafkin, Scot C. R.; Wimmer-Schweingruber, Robert F.; Boettcher, Stephan; Boehm, Eckart; Guo, Jingnan;

Variation objective analyses for cyclone studies

NASA Technical Reports Server (NTRS)

Achtemeier, G. L.; Kidder, S. Q.; Ochs, H. T.

1985-01-01

The objectives were to: (1) develop an objective analysis technique that will maximize the information content of data available from diverse sources, with particular emphasis on the incorporation of observations from satellites with those from more traditional immersion techniques; and (2) to develop a diagnosis of the state of the synoptic scale atmosphere on a much finer scale over a much broader region than is presently possible to permit studies of the interactions and energy transfers between global, synoptic and regional scale atmospheric processes. The variational objective analysis model consists of the two horizontal momentum equations, the hydrostatic equation, and the integrated continuity equation for a dry hydrostatic atmosphere. Preliminary tests of the model with the SESMAE I data set are underway for 12 GMT 10 April 1979. At this stage of purpose of the analysis is not the diagnosis of atmospheric structures but rather the validation of the model. Model runs for rawinsonde data and with the precision modulus weights set to force most of the adjustment of the wind field to the mass field have produced 90 to 95 percent reductions in the imbalance of the initial data after only 4-cycles through the Euler-Lagrange equations. Sensitivity tests for linear stability of the 11 Euler-Lagrange equations that make up the VASP Model 1 indicate that there will be a lower limit to the scales of motion that can be resolved by this method. Linear stability criteria are violated where there is large horizontal wind shear near the upper tropospheric jet.

Study of the effect of wind speed on evaporation from soil through integrated modeling of atmospheric boundary layer and shallow subsurface

NASA Astrophysics Data System (ADS)

Davarzani, Hossein; Smits, Kathleen; Tolene, Ryan; Illangasekare, Tissa

2013-04-01

The study of the interaction between the land and atmosphere is paramount to our understanding of many emerging problems to include climate change, the movement of green house gases such as possible leaking of sequestered CO2 and the accurate detection of buried objects such as landmines. Soil moisture distribution in the shallow subsurface becomes a critical factor in all these problems. The heat and mass flux in the form of soil evaporation across the land surface couples the atmospheric boundary layer to the shallow subsurface. The coupling between land and the atmosphere leads to highly dynamic interactions between the porous media properties, transport processes and boundary conditions, resulting in dynamic evaporative behavior. However, the coupling at the land-atmospheric interface is rarely considered in most current models and their validation for practical applications. This is due to the complexity of the problem in field scenarios and the scarcity of field or laboratory data capable of testing and refining coupled energy and mass transfer theories. In most efforts to compute evaporation from soil, only indirect coupling is provided to characterize the interaction between non-isothermal multiphase flows under realistic atmospheric conditions even though heat and mass flux are controlled by the coupled dynamics of the land and the atmospheric boundary layer. In earlier drying modeling concepts, imposing evaporation flux (kinetic of relative humidity) and temperature as surface boundary condition is often needed. With the goal of improving our understanding of the land/atmospheric coupling, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model consists of the coupled equations of mass conservation for the liquid phase (water) and gas phase (water vapor and air) in porous medium with gas phase (water vapor and air) in free flow domain under non-isothermal, non-equilibrium conditions. The boundary conditions at the porous medium-free flow medium interface include dynamical, thermal and solutal equilibriums, and using the Beavers-Joseph slip boundary condition. What is unique about this model is that the evaporation rate and soil surface temperature conditions come directly from the model output. In order to experimentally validate the numerical results, we developed and used a unique two dimensional wind tunnel placed above a soil tank equipped with a network of different sensors. A series of experiments under varying boundary conditions, using a test sand for which the hydraulic and thermal properties were well characterized, were performed. Precision data for soil moisture, soil and air temperature and relative humidity, and also wind velocity under well-controlled transient heat and wind boundary conditions was generated. Results from numerical simulations were compared with experimental data. Results demonstrate that the coupling concept can predict the different stages of the drying process in porous media with good accuracy. Increasing the wind speed increases the first stage evaporation rate and decreases the transition time at low velocity values; then, at high values of wind speed the evaporation rate becomes less dependent of flow in free fluid. In the opposite, the impact of the wind speed on the second stage evaporation (diffusion dominant stage) is not significant. The proposed theoretical model can be used to predict the evaporation process where a porous medium flow is coupled to a free flow for different practical applications.

Spectral studies related to dissociation of HBr, HCl and BrO

NASA Technical Reports Server (NTRS)

Ginter, M. L.

1986-01-01

Concern over halogen catalyzed decomposition of O3 in the upper atmosphere has generated need for data on the atomic and molecular species X, HX and XO (where X is Cl and Br). Of special importance are Cl produced from freon decomposition and Cl and Br produced from natural processes and from other industrial and agricultural chemicals. Basic spectral data is provided on HCl, HBr, and BrO necessary to detect specific states and energy levels, to enable detailed modeling of the processes involving molecular dissociation, ionization, etc., and to help evaluate field experiments to check the validity of model calculations for these species in the upper atmosphere. Results contained in four published papers and two major spectral compilations are summarized together with other results obtained.

Preliminary Results from the AFRL-NASA W/V-Band Terrestrial Link Experiment in Albuquerque, NM

NASA Technical Reports Server (NTRS)

Zemba, Michael; Nessel, James; Houts, Jacquelynne; Tarasenko, Nicholas; Lane, Steven; Murrell, David

2016-01-01

Atmospheric propagation models and the measurements that train them are critical to the design of efficient and effective space-ground links. As communication systems advance to higher frequencies in search of higher data rates and open spectrum, a lack of data at these frequencies necessitates new measurements to properly develop, validate, and refine the models used for link budgeting and system design. In collaboration with the Air Force Research Laboratory (AFRL), NASA Glenn Research Center has deployed the WV-band Terrestrial Link Experiment (WTLE) in Albuquerque, NM to conduct a measurement campaign at 72 and 84 GHz, among the first atmospheric propagation measurements at these frequencies. WTLE has been operational since October 1, 2015, and the system design shall be herein discussed alongside preliminary results and performance.

New Parameterizations for Neutral and Ion-Induced Sulfuric Acid-Water Particle Formation in Nucleation and Kinetic Regimes

NASA Astrophysics Data System (ADS)

Määttänen, Anni; Merikanto, Joonas; Henschel, Henning; Duplissy, Jonathan; Makkonen, Risto; Ortega, Ismael K.; Vehkamäki, Hanna

2018-01-01

We have developed new parameterizations of electrically neutral homogeneous and ion-induced sulfuric acid-water particle formation for large ranges of environmental conditions, based on an improved model that has been validated against a particle formation rate data set produced by Cosmics Leaving OUtdoor Droplets (CLOUD) experiments at European Organization for Nuclear Research (CERN). The model uses a thermodynamically consistent version of the Classical Nucleation Theory normalized using quantum chemical data. Unlike the earlier parameterizations for H2SO4-H2O nucleation, the model is applicable to extreme dry conditions where the one-component sulfuric acid limit is approached. Parameterizations are presented for the critical cluster sulfuric acid mole fraction, the critical cluster radius, the total number of molecules in the critical cluster, and the particle formation rate. If the critical cluster contains only one sulfuric acid molecule, a simple formula for kinetic particle formation can be used: this threshold has also been parameterized. The parameterization for electrically neutral particle formation is valid for the following ranges: temperatures 165-400 K, sulfuric acid concentrations 104-1013 cm-3, and relative humidities 0.001-100%. The ion-induced particle formation parameterization is valid for temperatures 195-400 K, sulfuric acid concentrations 104-1016 cm-3, and relative humidities 10-5-100%. The new parameterizations are thus applicable for the full range of conditions in the Earth's atmosphere relevant for binary sulfuric acid-water particle formation, including both tropospheric and stratospheric conditions. They are also suitable for describing particle formation in the atmosphere of Venus.

The validation of AIRS retrievals

NASA Technical Reports Server (NTRS)

Fetzer, Eric J.; Olsen, Edward T.; Chen, Luke L.; Hagan, Denise E.; Fishbein, Evan; McMillin, Larry; Zhou, Jiang; McMillan, Wallace W.

2003-01-01

The initial validation of Atmospheric Infrared Sounder (SIRS) experiment retrievals were completed in August 2003 as part of public release of version 3.0 data. The associated analyses are reported at http://daac.gsfc.nasa.gov/atmodyn/airs/, where data may be accessed. Here we describe some of those analyses, with an emphasis on cloud cleared radiances, atmospheric temperature profiles, sea surface temperature, total water vapor and atmospheric water vapor profiles. The results are applicable over ocean in the latitude band +/-40 degrees.

Combining VPL tools with NEMESIS to Probe Hot Jupiter Exoclimes for JWST

NASA Astrophysics Data System (ADS)

Afrin Badhan, Mahmuda; Kopparapu, Ravi Kumar; Domagal-Goldman, Shawn; Hébrard, Eric; Deming, Drake; Barstow, Joanna; Claire, Mark; Irwin, Patrick GJ; Mandell, Avi; Batalha, Natasha; Garland, Ryan

2016-06-01

Hot Jupiters are the most readily detected exoplanets by present technology. Since the scorching temperatures (>1000K) from high stellar irradiation levels do not allow for cold traps to form in their atmospheres, we can constrain their envelope’s elemental composition with greater confidence compared to our own Jupiter. Thus highly irradiated giant exoplanets hold keys to advancing our understanding of the origin and evolution of planetary systems.Constraining the atmospheric constituents through retrieval methods demands high-precision spectroscopic measurements and robust models to match those measurements. The former will be provided by NASA’s upcoming missions such as JWST. We meet the latter by producing self-consistent retrievals. Here I present modeling results for the temperature structure and photochemical gas abundances of water, methane, carbon dioxide and carbon monoxide, in the dayside atmospheres of selected H2-dominated hot Jupiters observed by present space missions and JWST/NIRSpec simulations, for two [C]/[O] metallicity ratios.The photochemical models were computed using a recently upgraded version of the NASA Astrobiology Institute’s VPL/Atmos software suite. For the radiative transfer and retrieval work, I have utilized a combination of two different numerical approaches in the extensively validated NEMESIS Atmospheric Retrieval Algorithm (Oxford Planetary Group). I have also represented the temperature profile in an analytical radiative equilibrium form to ascertain their physical plausibility. Finally, high-temperature (T> 1000K) spectroscopic opacity databases are slowly but continually being improved. Since this carries the potential of impacting irradiated atmospheric models quite significantly, I also talk about the potential observable impact of such improvements on the retrieval results.

Solar Wind Interaction with the Martian Upper Atmosphere at Early Mars/Extreme Solar Conditions

NASA Astrophysics Data System (ADS)

Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.

2014-12-01

The investigation of ion escape fluxes from Mars, resulting from the solar wind interaction with its upper atmosphere/ionosphere, is important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~ 300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model output fields into the 3-D BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid MHD model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres. This feature allows us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model output fields are used as the input for the multi-fluid MHD model and the M-GITM is used as input into the AMPS exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD calculations (1-way coupled) for 2.5 GYA conditions and/or extreme solar conditions for present day Mars (high solar wind velocities, high solar wind dynamic pressure, and high solar irradiance conditions, etc.). Present day extreme conditions may result in MF-MHD outputs that are similar to 2.5 GYA cases. The crustal field orientations are also considered in this study. By comparing estimates of past ion escape rates with the current ion loss rates to be returned by the MAVEN spacecraft (2013-2016), we can better constrain the total ion loss to space over Mars history, and thus enhance the science returned from the MAVEN mission.

A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation.

PubMed

Breton, S-P; Sumner, J; Sørensen, J N; Hansen, K S; Sarmast, S; Ivanell, S

2017-04-13

Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple wake situations is also supplied. Some typical results for wind turbine and wind farm flows are presented to illustrate best practices for carrying out high-fidelity LES of wind farms under various atmospheric and terrain conditions.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Author(s).

A survey of modelling methods for high-fidelity wind farm simulations using large eddy simulation

PubMed Central

Sumner, J.; Sørensen, J. N.; Hansen, K. S.; Sarmast, S.; Ivanell, S.

2017-01-01

Large eddy simulations (LES) of wind farms have the capability to provide valuable and detailed information about the dynamics of wind turbine wakes. For this reason, their use within the wind energy research community is on the rise, spurring the development of new models and methods. This review surveys the most common schemes available to model the rotor, atmospheric conditions and terrain effects within current state-of-the-art LES codes, of which an overview is provided. A summary of the experimental research data available for validation of LES codes within the context of single and multiple wake situations is also supplied. Some typical results for wind turbine and wind farm flows are presented to illustrate best practices for carrying out high-fidelity LES of wind farms under various atmospheric and terrain conditions. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265021

Sensor System Performance Evaluation and Benefits from the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I)

NASA Technical Reports Server (NTRS)

Larar, A.; Zhou, D.; Smith, W.

2009-01-01

Advanced satellite sensors are tasked with improving global-scale measurements of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring, and environmental change detection. Validation of the entire measurement system is crucial to achieving this goal and thus maximizing research and operational utility of resultant data. Field campaigns employing satellite under-flights with well-calibrated FTS sensors aboard high-altitude aircraft are an essential part of this validation task. The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed-Interferometer (NAST-I) has been a fundamental contributor in this area by providing coincident high spectral/spatial resolution observations of infrared spectral radiances along with independently-retrieved geophysical products for comparison with like products from satellite sensors being validated. This paper focuses on some of the challenges associated with validating advanced atmospheric sounders and the benefits obtained from employing airborne interferometers such as the NAST-I. Select results from underflights of the Aqua Atmospheric InfraRed Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI) obtained during recent field campaigns will be presented.

Water vapour correction of the daily 1 km AVHRR global land dataset: Part I validation and use of the Water Vapour input field

USGS Publications Warehouse

DeFelice, Thomas P.; Lloyd, D.; Meyer, D.J.; Baltzer, T. T.; Piraina, P.

2003-01-01

An atmospheric correction algorithm developed for the 1 km Advanced Very High Resolution Radiometer (AVHRR) global land dataset was modified to include a near real-time total column water vapour data input field to account for the natural variability of atmospheric water vapour. The real-time data input field used for this study is the Television and Infrared Observational Satellite (TIROS) Operational Vertical Sounder (TOVS) Pathfinder A global total column water vapour dataset. It was validated prior to its use in the AVHRR atmospheric correction process using two North American AVHRR scenes, namely 13 June and 28 November 1996. The validation results are consistent with those reported by others and entail a comparison between TOVS, radiosonde, experimental sounding, microwave radiometer, and data from a hand-held sunphotometer. The use of this data layer as input to the AVHRR atmospheric correction process is discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Shang-Min; Grosheintz, Luc; Kitzmann, Daniel

We present an open-source and validated chemical kinetics code for studying hot exoplanetary atmospheres, which we name VULCAN. It is constructed for gaseous chemistry from 500 to 2500 K, using a reduced C–H–O chemical network with about 300 reactions. It uses eddy diffusion to mimic atmospheric dynamics and excludes photochemistry. We have provided a full description of the rate coefficients and thermodynamic data used. We validate VULCAN by reproducing chemical equilibrium and by comparing its output versus the disequilibrium-chemistry calculations of Moses et al. and Rimmer and Helling. It reproduces the models of HD 189733b and HD 209458b by Mosesmore » et al., which employ a network with nearly 1600 reactions. We also use VULCAN to examine the theoretical trends produced when the temperature–pressure profile and carbon-to-oxygen ratio are varied. Assisted by a sensitivity test designed to identify the key reactions responsible for producing a specific molecule, we revisit the quenching approximation and find that it is accurate for methane but breaks down for acetylene, because the disequilibrium abundance of acetylene is not directly determined by transport-induced quenching, but is rather indirectly controlled by the disequilibrium abundance of methane. Therefore we suggest that the quenching approximation should be used with caution and must always be checked against a chemical kinetics calculation. A one-dimensional model atmosphere with 100 layers, computed using VULCAN, typically takes several minutes to complete. VULCAN is part of the Exoclimes Simulation Platform (ESP; exoclime.net) and publicly available at https://github.com/exoclime/VULCAN.« less

Global land-atmosphere coupling associated with cold climate processes

NASA Astrophysics Data System (ADS)

Dutra, Emanuel

This dissertation constitutes an assessment of the role of cold processes, associated with snow cover, in controlling the land-atmosphere coupling. The work was based on model simulations, including offline simulations with the land surface model HTESSEL, and coupled atmosphere simulations with the EC-EARTH climate model. A revised snow scheme was developed and tested in HTESSEL and EC-EARTH. The snow scheme is currently operational at the European Centre for Medium-Range Weather Forecasts integrated forecast system, and in the default configuration of EC-EARTH. The improved representation of the snowpack dynamics in HTESSEL resulted in improvements in the near surface temperature simulations of EC-EARTH. The new snow scheme development was complemented with the option of multi-layer version that showed its potential in modeling thick snowpacks. A key process was the snow thermal insulation that led to significant improvements of the surface water and energy balance components. Similar findings were observed when coupling the snow scheme to lake ice, where lake ice duration was significantly improved. An assessment on the snow cover sensitivity to horizontal resolution, parameterizations and atmospheric forcing within HTESSEL highlighted the role of the atmospheric forcing accuracy and snowpack parameterizations in detriment of horizontal resolution over flat regions. A set of experiments with and without free snow evolution was carried out with EC-EARTH to assess the impact of the interannual variability of snow cover on near surface and soil temperatures. It was found that snow cover interannual variability explained up to 60% of the total interannual variability of near surface temperature over snow covered regions. Although these findings are model dependent, the results showed consistency with previously published work. Furthermore, the detailed validation of the snow dynamics simulations in HTESSEL and EC-EARTH guarantees consistency of the results.

Statistical uncertainty of eddy flux-based estimates of gross ecosystem carbon exchange at Howland Forest, Maine

Treesearch

S.C. Hagen; B.H. Braswell; E. Linder; S. Frolking; A.D. Richardson; David Hollinger. D.Y; Hollinger. D.Y

2006-01-01

We present an uncertainty analysis of gross ecosystem carbon exchange (GEE) estimates derived from 7 years of continuous eddy covariance measurements of forest atmosphere CO2 fluxes at Howland Forest, Maine, USA. These data, which have high temporal resolution, can be used to validate process modeling analyses, remote sensing assessments, and field surveys. However,...

Tidal atmospheric and ocean loading in VLBI analysis

NASA Astrophysics Data System (ADS)

Girdiuk, Anastasiia; Schindelegger, Michael; Böhm, Johannes

2016-04-01

In VLBI (Very Long Baseline Interferometry) analysis, reductions for tidal atmospheric and ocean loading are commonly used according to the IERS Conventions. In this presentation we examine such loading corrections from contemporary geophysical models within routine VLBI processing and discuss the internal consistency of the applied corrections for various effects. In detail, two gravitational ocean tide models, FES2004 and the recent FES2012 atlas with a much finer horizontal resolution and an improved description of hydrodynamic processes, are employed. Moreover, the contribution of atmospheric tidal loading is also re-considered based on data taken from two providers of station displacements, Goddard Space Flight Center and the TU Wien group. Those two models differ in terms of the underlying meteorological data, which can be a reason for inconsistency of VLBI reductions and may lead to systematics in the VLBI products at tidal frequencies. We validate this assumption in terms of Earth rotation parameters, by a tidal analysis of diurnal and semi-diurnal universal time and semi-diurnal polar motion variations as determined with the Vienna VLBI Software. Applying the loading models in a consistent way still leads to unexplained residuals at about 4-5 μas in the diurnal polar motion band, thus limiting the possibility of assessing geophysical models at this particular frequency.

Simulating CO2 profiles using NIES TM and comparison with HIAPER Pole-to-Pole Observations

NASA Astrophysics Data System (ADS)

Song, C.; Maksyutov, S.; Belikov, D.; Takagi, H.; Shu, J.

2015-03-01

We present a study on validation of the National Institute for Environmental Studies Transport Model (NIES TM) by comparing to observed vertical profiles of atmospheric CO2. The model uses a hybrid sigma-isentropic (σ-θ) vertical coordinate that employs both terrain-following and isentropic parts switched smoothly in the stratosphere. The model transport is driven by reanalyzed meteorological fields and designed to simulate seasonal and diurnal cycles, synoptic variations, and spatial distributions of atmospheric chemical constituents in the troposphere. The model simulations were run for biosphere, fossil fuel, air-ocean exchange, biomass burning and inverse correction fluxes of carbon dioxide (CO2) by GOSAT Level 4 product. We compared the NIES TM simulated fluxes with data from the HIAPER Pole-to-Pole Observations (HIPPO) Merged 10 s Meteorology, Atmospheric Chemistry, and Aerosol Data, including HIPPO-1, HIPPO-2 and HIPPO-3 from 128.0° E to -84.0° W, and 87.0° N to -67.2° S. The simulation results were compared with CO2 observations made in January and November 2009, and March and April 2010. The analysis attests that the model is good enough to simulate vertical profiles with errors generally within 1-2 ppmv, except for the lower stratosphere in the Northern Hemisphere high latitudes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saumon, D.; Holberg, J. B.; Kowalski, P. M., E-mail: dsaumon@lanl.gov, E-mail: holberg@argus.lpl.arizona.edu, E-mail: p.kowalski@fz-juelich.de

The atmospheres of very cool, hydrogen-rich white dwarfs (WDs) (T{sub eff} < 6000 K) are challenging to model because of the increased complexity of the equation of state, chemical equilibrium, and opacity sources in a low-temperature, weakly ionized dense gas. In particular, many models that assume relatively simple models for the broadening of atomic levels and mostly ideal gas physics overestimate the flux in the blue part of their spectra. A solution to this problem that has met with some success is that additional opacity at short wavelengths comes for the extreme broadening of the Lyman α line of atomicmore » H by collisions primarily with H{sub 2}. For the purpose of validating this model more rigorously, we acquired Hubble Space Telescope STIS spectra of eight very cool WDs (five DA and three DC stars). Combined with their known parallaxes, BVRIJHK, and Spitzer IRAC photometry, we analyze their entire spectral energy distribution (from 0.24 to 9.3 μm) with a large grid of model atmospheres and synthetic spectra. We find that the red wing of the Lyman α line reproduces the rapidly decreasing near-UV flux of these very cool stars very well. We determine better constrained values of T{sub eff} and gravity as well as upper limits to the helium abundance in their atmospheres.« less

Competition among Li+, Na+, K+ and Rb+ Monovalent Ions for DNA in Molecular Dynamics Simulations using the Additive CHARMM36 and Drude Polarizable Force Fields

PubMed Central

Savelyev, Alexey; MacKerell, Alexander D.

2015-01-01

In the present study we report on interactions of and competition between monovalent ions for two DNA sequences in MD simulations. Efforts included the development and validation of parameters for interactions among the first-group monovalent cations, Li+, Na+, K+ and Rb+, and DNA in the Drude polarizable and additive CHARMM36 force fields (FF). The optimization process targeted gas-phase QM interaction energies of various model compounds with ions and osmotic pressures of bulk electrolyte solutions of chemically relevant ions. The optimized ionic parameters are validated against counterion condensation theory and buffer exchange-atomic emission spectroscopy measurements providing quantitative data on the competitive association of different monovalent ions with DNA. Comparison between experimental and MD simulation results demonstrates that, compared to the additive CHARMM36 model, the Drude FF provides an improved description of the general features of the ionic atmosphere around DNA and leads to closer agreement with experiment on the ionic competition within the ion atmosphere. Results indicate the importance of extended simulation systems on the order of 25 Å beyond the DNA surface to obtain proper convergence of ion distributions. PMID:25751286

AVALON: definition and modeling of a vertical takeoff and landing UAV

NASA Astrophysics Data System (ADS)

Silva, N. B. F.; Marconato, E. A.; Branco, K. R. L. J. C.

2015-09-01

Unmanned Aerial Vehicles (UAVs) have been used in numerous applications, like remote sensing, precision agriculture and atmospheric data monitoring. Vertical takeoff and landing (VTOL) is a modality of these aircrafts, which are capable of taking off and landing vertically, like a helicopter. This paper presents the definition and modeling of a fixed- wing VTOL, named AVALON (Autonomous VerticAL takeOff and laNding), which has the advantages of traditional aircrafts with improved performance and can take off and land in small areas. The principles of small UAVs development were followed to achieve a better design and to increase the range of applications for this VTOL. Therefore, we present the design model of AVALON validated in a flight simulator and the results show its validity as a physical option for an UAV platform.

Use of stable isotope signatures to determine mercury sources in the Great Lakes

USGS Publications Warehouse

Lepak, Ryan F.; Yin, Runsheng; Krabbenhoft, David P.; Ogorek, Jacob M.; DeWild, John F.; Holsen, Thomas M.; Hurley, James P.

2015-01-01

Sources of mercury (Hg) in Great Lakes sediments were assessed with stable Hg isotope ratios using multicollector inductively coupled plasma mass spectrometry. An isotopic mixing model based on mass-dependent (MDF) and mass-independent fractionation (MIF) (δ202Hg and Δ199Hg) identified three primary Hg sources for sediments: atmospheric, industrial, and watershed-derived. Results indicate atmospheric sources dominate in Lakes Huron, Superior, and Michigan sediments while watershed-derived and industrial sources dominate in Lakes Erie and Ontario sediments. Anomalous Δ200Hg signatures, also apparent in sediments, provided independent validation of the model. Comparison of Δ200Hg signatures in predatory fish from three lakes reveals that bioaccumulated Hg is more isotopically similar to atmospherically derived Hg than a lake’s sediment. Previous research suggests Δ200Hg is conserved during biogeochemical processing and odd mass-independent fractionation (MIF) is conserved during metabolic processing, so it is suspected even is similarly conserved. Given these assumptions, our data suggest that in some cases, atmospherically derived Hg may be a more important source of MeHg to higher trophic levels than legacy sediments in the Great Lakes.

Using the Firefly optimization method to weight an ensemble of rainfall forecasts from the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS)

NASA Astrophysics Data System (ADS)

dos Santos, A. F.; Freitas, S. R.; de Mattos, J. G. Z.; de Campos Velho, H. F.; Gan, M. A.; da Luz, E. F. P.; Grell, G. A.

2013-09-01

In this paper we consider an optimization problem applying the metaheuristic Firefly algorithm (FY) to weight an ensemble of rainfall forecasts from daily precipitation simulations with the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS) over South America during January 2006. The method is addressed as a parameter estimation problem to weight the ensemble of precipitation forecasts carried out using different options of the convective parameterization scheme. Ensemble simulations were performed using different choices of closures, representing different formulations of dynamic control (the modulation of convection by the environment) in a deep convection scheme. The optimization problem is solved as an inverse problem of parameter estimation. The application and validation of the methodology is carried out using daily precipitation fields, defined over South America and obtained by merging remote sensing estimations with rain gauge observations. The quadratic difference between the model and observed data was used as the objective function to determine the best combination of the ensemble members to reproduce the observations. To reduce the model rainfall biases, the set of weights determined by the algorithm is used to weight members of an ensemble of model simulations in order to compute a new precipitation field that represents the observed precipitation as closely as possible. The validation of the methodology is carried out using classical statistical scores. The algorithm has produced the best combination of the weights, resulting in a new precipitation field closest to the observations.

Laboratory Measurement of Bidirectional Reflectance of Radiometric Tarps

NASA Technical Reports Server (NTRS)

Knowlton, Kelly

2006-01-01

Objectives: a) To determine the magnitude of radiometric tarp BRDF; b) To determine whether an ASD FieldSpec Pro spectroradiometer can be used to perform the experiment. Radiometric tarps with nominal reflectance values of 52%, 35%, and 3.5%, deployed for IKONOS. QuickBird, and OrbView-3 overpasses Ground-based spectroradiometric measurements of tarp and Spectralon@ panel taken during overpass using ASD FieldSpec Pro spectroradiometer, and tarp reflectance calculated. Reflectance data used in atmospheric radiative transfer model (MODTRAN) to predict satellite at-sensor radiance for radiometric calibration. Reflectance data also used to validate atmospheric correction of high-spatial-resolution multispectral image products

SEASAT economic assessment

NASA Technical Reports Server (NTRS)

Hicks, K.; Steele, W.

1974-01-01

The SEASAT program will provide scientific and economic benefits from global remote sensing of the ocean's dynamic and physical characteristics. The program as presently envisioned consists of: (1) SEASAT A; (2) SEASAT B; and (3) Operational SEASAT. This economic assessment was to identify, rationalize, quantify and validate the economic benefits evolving from SEASAT. These benefits will arise from improvements in the operating efficiency of systems that interface with the ocean. SEASAT data will be combined with data from other ocean and atmospheric sampling systems and then processed through analytical models of the interaction between oceans and atmosphere to yield accurate global measurements and global long range forecasts of ocean conditions and weather.

Optimisation of dispersion parameters of Gaussian plume model for CO₂ dispersion.

PubMed

Liu, Xiong; Godbole, Ajit; Lu, Cheng; Michal, Guillaume; Venton, Philip

2015-11-01

The carbon capture and storage (CCS) and enhanced oil recovery (EOR) projects entail the possibility of accidental release of carbon dioxide (CO2) into the atmosphere. To quantify the spread of CO2 following such release, the 'Gaussian' dispersion model is often used to estimate the resulting CO2 concentration levels in the surroundings. The Gaussian model enables quick estimates of the concentration levels. However, the traditionally recommended values of the 'dispersion parameters' in the Gaussian model may not be directly applicable to CO2 dispersion. This paper presents an optimisation technique to obtain the dispersion parameters in order to achieve a quick estimation of CO2 concentration levels in the atmosphere following CO2 blowouts. The optimised dispersion parameters enable the Gaussian model to produce quick estimates of CO2 concentration levels, precluding the necessity to set up and run much more complicated models. Computational fluid dynamics (CFD) models were employed to produce reference CO2 dispersion profiles in various atmospheric stability classes (ASC), different 'source strengths' and degrees of ground roughness. The performance of the CFD models was validated against the 'Kit Fox' field measurements, involving dispersion over a flat horizontal terrain, both with low and high roughness regions. An optimisation model employing a genetic algorithm (GA) to determine the best dispersion parameters in the Gaussian plume model was set up. Optimum values of the dispersion parameters for different ASCs that can be used in the Gaussian plume model for predicting CO2 dispersion were obtained.

Atmospheric Dispersal and Dispostion of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. Keating; W.Statham

2004-02-12

The purpose of this model report is to provide documentation of the conceptual and mathematical model (ASHPLUME) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. The ASHPLUME conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The ASHPLUME mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the groundmore » surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report will improve and clarify the previous documentation of the ASHPLUME mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model.« less

Modeling of the Plume Development Phase of the Shoemaker-Levy 9 Comet Impact

NASA Astrophysics Data System (ADS)

Palotai, Csaba J.; Korycansky, D.; Deming, D.; Harrington, J.

2008-09-01

We present a progress report on our numerical simulations of the plume blowout and flight/splash phases of the Shoemaker-Levy 9 (SL9) comet impact into Jupiter's atmosphere. For this project we have modified the ZEUS-MP/2 three-dimensional hydrodynamic model (Hayes et al. ApJ.SS. 165. 174-183, 2006) to be suitable for Jovian atmospheric simulations. To initialize our model we map the final state of high-resolution SL9 impact simulations of Korycansky et al. (ApJ 646. 642-652, 2006) onto our larger, stationary grid. In the current phase of the research we investigate how the dynamical chaos in the impact model affects simulations of the subsequent phases. We adapt the atmospheric radiation model from the 2D splash calculation of Deming and Harrington (ApJ 561. 455-467, 2001) to calculate realistic wavelength-dependent lightcurves and low-resolution spectra. Our goal is to compare synthetic images created from model output to the data taken by the Hubble Space Telescope of plumes on the limb of Jupiter during the impacts of various SL9 fragments (Hammel et al. Science 267. 1288-1296, 1995). Details of the model, validation of the code, and results of our latest simulations will be presented. This material is based on work supported by National Science Foundation Grant No. 0307638 and National Aeronautics and Space Administration Grant No. NNG 04GQ35G .

Simplification and Validation of a Spectral-Tensor Model for Turbulence Including Atmospheric Stability

NASA Astrophysics Data System (ADS)

Chougule, Abhijit; Mann, Jakob; Kelly, Mark; Larsen, Gunner C.

2018-06-01

A spectral-tensor model of non-neutral, atmospheric-boundary-layer turbulence is evaluated using Eulerian statistics from single-point measurements of the wind speed and temperature at heights up to 100 m, assuming constant vertical gradients of mean wind speed and temperature. The model has been previously described in terms of the dissipation rate ɛ , the length scale of energy-containing eddies L, a turbulence anisotropy parameter Γ, the Richardson number Ri, and the normalized rate of destruction of temperature variance η _θ ≡ ɛ _θ /ɛ . Here, the latter two parameters are collapsed into a single atmospheric stability parameter z / L using Monin-Obukhov similarity theory, where z is the height above the Earth's surface, and L is the Obukhov length corresponding to Ri,η _θ. Model outputs of the one-dimensional velocity spectra, as well as cospectra of the streamwise and/or vertical velocity components, and/or temperature, and cross-spectra for the spatial separation of all three velocity components and temperature, are compared with measurements. As a function of the four model parameters, spectra and cospectra are reproduced quite well, but horizontal temperature fluxes are slightly underestimated in stable conditions. In moderately unstable stratification, our model reproduces spectra only up to a scale ˜ 1 km. The model also overestimates coherences for vertical separations, but is less severe in unstable than in stable cases.

Simulation for Prediction of Entry Article Demise (SPEAD): An Analysis Tool for Spacecraft Safety Analysis and Ascent/Reentry Risk Assessment

NASA Technical Reports Server (NTRS)

Ling, Lisa

2014-01-01

For the purpose of performing safety analysis and risk assessment for a potential off-nominal atmospheric reentry resulting in vehicle breakup, a synthesis of trajectory propagation coupled with thermal analysis and the evaluation of node failure is required to predict the sequence of events, the timeline, and the progressive demise of spacecraft components. To provide this capability, the Simulation for Prediction of Entry Article Demise (SPEAD) analysis tool was developed. The software and methodology have been validated against actual flights, telemetry data, and validated software, and safety/risk analyses were performed for various programs using SPEAD. This report discusses the capabilities, modeling, validation, and application of the SPEAD analysis tool.

Observation- and model-based estimates of particulate dry nitrogen deposition to the oceans

NASA Astrophysics Data System (ADS)

Baker, Alex R.; Kanakidou, Maria; Altieri, Katye E.; Daskalakis, Nikos; Okin, Gregory S.; Myriokefalitakis, Stelios; Dentener, Frank; Uematsu, Mitsuo; Sarin, Manmohan M.; Duce, Robert A.; Galloway, James N.; Keene, William C.; Singh, Arvind; Zamora, Lauren; Lamarque, Jean-Francois; Hsu, Shih-Chieh; Rohekar, Shital S.; Prospero, Joseph M.

2017-07-01

Anthropogenic nitrogen (N) emissions to the atmosphere have increased significantly the deposition of nitrate (NO3-) and ammonium (NH4+) to the surface waters of the open ocean, with potential impacts on marine productivity and the global carbon cycle. Global-scale understanding of the impacts of N deposition to the oceans is reliant on our ability to produce and validate models of nitrogen emission, atmospheric chemistry, transport and deposition. In this work, ˜ 2900 observations of aerosol NO3- and NH4+ concentrations, acquired from sampling aboard ships in the period 1995-2012, are used to assess the performance of modelled N concentration and deposition fields over the remote ocean. Three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) were selected, in which the density and distribution of observational data were considered sufficient to provide effective comparison to model products. All of these study regions are affected by transport and deposition of mineral dust, which alters the deposition of N, due to uptake of nitrogen oxides (NOx) on mineral surfaces. Assessment of the impacts of atmospheric N deposition on the ocean requires atmospheric chemical transport models to report deposition fluxes; however, these fluxes cannot be measured over the ocean. Modelling studies such as the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), which only report deposition flux, are therefore very difficult to validate for dry deposition. Here, the available observational data were averaged over a 5° × 5° grid and compared to ACCMIP dry deposition fluxes (ModDep) of oxidised N (NOy) and reduced N (NHx) and to the following parameters from the Tracer Model 4 of the Environmental Chemical Processes Laboratory (TM4): ModDep for NOy, NHx and particulate NO3- and NH4+, and surface-level particulate NO3- and NH4+ concentrations. As a model ensemble, ACCMIP can be expected to be more robust than TM4, while TM4 gives access to speciated parameters (NO3- and NH4+) that are more relevant to the observed parameters and which are not available in ACCMIP. Dry deposition fluxes (CalDep) were calculated from the observed concentrations using estimates of dry deposition velocities. Model-observation ratios (RA, n), weighted by grid-cell area and number of observations, were used to assess the performance of the models. Comparison in the three study regions suggests that TM4 overestimates NO3- concentrations (RA, n = 1.4-2.9) and underestimates NH4+ concentrations (RA, n = 0.5-0.7), with spatial distributions in the tropical Atlantic and northern Indian Ocean not being reproduced by the model. In the case of NH4+ in the Indian Ocean, this discrepancy was probably due to seasonal biases in the sampling. Similar patterns were observed in the various comparisons of CalDep to ModDep (RA, n = 0.6-2.6 for NO3-, 0.6-3.1 for NH4+). Values of RA, n for NHx CalDep-ModDep comparisons were approximately double the corresponding values for NH4+ CalDep-ModDep comparisons due to the significant fraction of gas-phase NH3 deposition incorporated in the TM4 and ACCMIP NHx model products. All of the comparisons suffered due to the scarcity of observational data and the large uncertainty in dry deposition velocities used to derive deposition fluxes from concentrations. These uncertainties have been a major limitation on estimates of the flux of material to the oceans for several decades. Recommendations are made for improvements in N deposition estimation through changes in observations, modelling and model-observation comparison procedures. Validation of modelled dry deposition requires effective comparisons to observable aerosol-phase species' concentrations, and this cannot be achieved if model products only report dry deposition flux over the ocean.

Observation- and Model-Based Estimates of Particulate Dry Nitrogen Deposition to the Oceans.

PubMed

Baker, Alex R; Kanakidou, Maria; Altieri, Katye E; Daskalakis, Nikos; Okin, Gregory S; Myriokefalitakis, Stelios; Dentener, Frank; Uematsu, Mitsuo; Sarin, Manmohan M; Duce, Robert A; Galloway, James N; Keene, William C; Singh, Arvind; Zamora, Lauren; Lamarque, Jean-Francois; Hsu, Shih-Chieh; Rohekar, Shital S; Prospero, Joseph M

2017-01-01

Anthropogenic nitrogen (N) emissions to the atmosphere have increased significantly the deposition of nitrate (NO 3 - ) and ammonium (NH 4 + ) to the surface waters of the open ocean, with potential impacts on marine productivity and the global carbon cycle. Global-scale understanding of the impacts of N deposition to the oceans is reliant on our ability to produce and validate models of nitrogen emission, atmospheric chemistry, transport and deposition. In this work, ~2900 observations of aerosol NO 3 - and NH 4 + concentrations, acquired from sampling aboard ships in the period 1995 - 2012, are used to assess the performance of modelled N concentration and deposition fields over the remote ocean. Three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) were selected, in which the density and distribution of observational data were considered sufficient to provide effective comparison to model products. All of these study regions are affected by transport and deposition of mineral dust, which alters the deposition of N, due to uptake of nitrogen oxides (NO x ) on mineral surfaces. Assessment of the impacts of atmospheric N deposition on the ocean requires atmospheric chemical transport models to report deposition fluxes, however these fluxes cannot be measured over the ocean. Modelling studies such as the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), which only report deposition flux are therefore very difficult to validate for dry deposition. Here the available observational data were averaged over a 5° × 5° grid and compared to ACCMIP dry deposition fluxes (ModDep) of oxidised N (NO y ) and reduced N (NH x ) and to the following parameters from the TM4-ECPL (TM4) model: ModDep for NO y , NH x and particulate NO 3 - and NH 4 + , and surface-level particulate NO 3 - and NH 4 + concentrations. As a model ensemble, ACCMIP can be expected to be more robust than TM4, while TM4 gives access to speciated parameters (NO 3 - and NH 4 + ) that are more relevant to the observed parameters and which are not available in ACCMIP. Dry deposition fluxes (CalDep) were calculated from the observed concentrations using estimates of dry deposition velocities. Model - observation ratios, weighted by grid-cell area and numbers of observations, (R A,n ) were used to assess the performance of the models. Comparison in the three study regions suggests that TM4 over-estimates NO 3 - concentrations (R A,n = 1.4 - 2.9) and under-estimates NH 4 + concentrations (R A,n = 0.5 - 0.7), with spatial distributions in the tropical Atlantic and northern Indian Ocean not being reproduced by the model. In the case of NH 4 + in the Indian Ocean, this discrepancy was probably due to seasonal biases in the sampling. Similar patterns were observed in the various comparisons of CalDep to ModDep (R A,n = 0.6 - 2.6 for NO 3 - , 0.6 - 3.1 for NH 4 + ). Values of R A,n for NH x CalDep - ModDep comparisons were approximately double the corresponding values for NH 4 + CalDep - ModDep comparisons due to the significant fraction of gas-phase NH 3 deposition incorporated in the TM4 and ACCMIP NH x model products. All of the comparisons suffered due to the scarcity of observational data and the large uncertainty in dry deposition velocities used to derive deposition fluxes from concentrations. These uncertainties have been a major limitation on estimates of the flux of material to the oceans for several decades. Recommendations are made for improvements in N deposition estimation through changes in observations, modelling and model - observation comparison procedures. Validation of modelled dry deposition requires effective comparisons to observable aerosol-phase species concentrations and this cannot be achieved if model products only report dry deposition flux over the ocean.

GOSAT validation out standing in the field: A case study of satellite validation using the SSEC Portable Atmospheric Research Center (SPARC)

NASA Astrophysics Data System (ADS)

Wagner, T. J.; Borg, L. A.; Feltz, M.; Gero, P. J.; Knuteson, R. O.; Olson, E.

2016-12-01

The Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison has developed the SSEC Portable Atmospheric Research Center (SPARC), a mobile 11 m trailer that houses numerous in situ and ground-based remote sensing instruments. Available instrumentation includes the Atmospheric Emitted Radiance Interferometer (AERI), a hyperspectral infrared radiometer from which trace gas concentrations and profiles of temperature and water vapor can be retrieved; the High Spectral Resolution Lidar (HSRL), a multichannel lidar capable of directly retrieving profiles of optical depth and backscatter depolarization; and a Doppler lidar wind profiler. The remote instrumentation suite is complemented by surface meteorology observations and a radiosonde ground station. Collectively, these instruments enable SPARC to participate in a wide variety of field studies, including meteorological field experiments and ground-based satellite calibration and validation studies. In August 2016, SPARC traveled to the Chequamegon National Forest in northern Wisconsin for a two week long deployment alongside the WLEF-TV tower. This 447 m tower houses long-term observations of thermodynamic and atmospheric composition at multiple heights, enabling studies of phenomena like atmospheric/land surface interactions and carbon uptake. During this deployment, SPARC launched radiosondes coincident with clear-sky overpasses of the Greenhouse gases Observing SATellite (GOSAT). Thermodynamic profiles from the radiosondes and AERI combined with the trace gas observations from the tower were used to validate the GOSAT observations of carbon dioxide and methane. The on-site presence of SPARC allowed for better characterization of the environment and greater observational certainty than was possible with the tower alone. Examples from this particular validation study as well as a discussion of how SPARC can contribute to other satellite calibration and validation investigations will be presented.

Aerosol modelling and validation during ESCOMPTE 2001

NASA Astrophysics Data System (ADS)

Cousin, F.; Liousse, C.; Cachier, H.; Bessagnet, B.; Guillaume, B.; Rosset, R.

The ESCOMPTE 2001 programme (Atmospheric Research. 69(3-4) (2004) 241) has resulted in an exhaustive set of dynamical, radiative, gas and aerosol observations (surface and aircraft measurements). A previous paper (Atmospheric Research. (2004) in press) has dealt with dynamics and gas-phase chemistry. The present paper is an extension to aerosol formation, transport and evolution. To account for important loadings of primary and secondary aerosols and their transformation processes in the ESCOMPTE domain, the ORISAM aerosol module (Atmospheric Environment. 35 (2001) 4751) was implemented on-line in the air-quality Meso-NH-C model. Additional developments have been introduced in ORganic and Inorganic Spectral Aerosol Module (ORISAM) to improve the comparison between simulations and experimental surface and aircraft field data. This paper discusses this comparison for a simulation performed during one selected day, 24 June 2001, during the Intensive Observation Period IOP2b. Our work relies on BC and OCp emission inventories specifically developed for ESCOMPTE. This study confirms the need for a fine resolution aerosol inventory with spectral chemical speciation. BC levels are satisfactorily reproduced, thus validating our emission inventory and its processing through Meso-NH-C. However, comparisons for reactive species generally denote an underestimation of concentrations. Organic aerosol levels are rather well simulated though with a trend to underestimation in the afternoon. Inorganic aerosol species are underestimated for several reasons, some of them have been identified. For sulphates, primary emissions were introduced. Improvement was obtained too for modelled nitrate and ammonium levels after introducing heterogeneous chemistry. However, no modelling of terrigeneous particles is probably a major cause for nitrates and ammonium underestimations. Particle numbers and size distributions are well reproduced, but only in the submicrometer range. Our work points out to the need of introducing coarse dust particles to further improve the simulation of PM-10 concentrations and more accurate modelling of gas-particle interactions.

Hydrogen and water desorption on the moon - Approximate, on-line simulations

NASA Technical Reports Server (NTRS)

Blanford, G. E.; Borgesen, P.; Moeller, W.; Maurette, M.; Monart, B.

1985-01-01

The basic models that have been used over the last 15 years to describe the accumulation and release of solar wind-related species at lunar conditions at the lunar surface are reviewed. Recent results which show that these models are not totally valid are discussed. It is suggested that mature lunar surface soils may act as efficient converters for transforming the flux of energetic solar wind protons into a flux of low-energy hydrogen and water molecules continuously injected into the lunar atmosphere.

High-resolution modelling of atmospheric dispersion of dense gas using TWODEE-2.1: application to the 1986 Lake Nyos limnic eruption

NASA Astrophysics Data System (ADS)

Folch, Arnau; Barcons, Jordi; Kozono, Tomofumi; Costa, Antonio

2017-06-01

Atmospheric dispersal of a gas denser than air can threat the environment and surrounding communities if the terrain and meteorological conditions favour its accumulation in topographic depressions, thereby reaching toxic concentration levels. Numerical modelling of atmospheric gas dispersion constitutes a useful tool for gas hazard assessment studies, essential for planning risk mitigation actions. In complex terrains, microscale winds and local orographic features can have a strong influence on the gas cloud behaviour, potentially leading to inaccurate results if not captured by coarser-scale modelling. We introduce a methodology for microscale wind field characterisation based on transfer functions that couple a mesoscale numerical weather prediction model with a microscale computational fluid dynamics (CFD) model for the atmospheric boundary layer. The resulting time-dependent high-resolution microscale wind field is used as input for a shallow-layer gas dispersal model (TWODEE-2.1) to simulate the time evolution of CO2 gas concentration at different heights above the terrain. The strategy is applied to review simulations of the 1986 Lake Nyos event in Cameroon, where a huge CO2 cloud released by a limnic eruption spread downslopes from the lake, suffocating thousands of people and animals across the Nyos and adjacent secondary valleys. Besides several new features introduced in the new version of the gas dispersal code (TWODEE-2.1), we have also implemented a novel impact criterion based on the percentage of human fatalities depending on CO2 concentration and exposure time. New model results are quantitatively validated using the reported percentage of fatalities at several locations. The comparison with previous simulations that assumed coarser-scale steady winds and topography illustrates the importance of high-resolution modelling in complex terrains.

Validating the accuracy of SO2 gas retrievals in the thermal infrared (8-14 μm)

NASA Astrophysics Data System (ADS)

Gabrieli, Andrea; Porter, John N.; Wright, Robert; Lucey, Paul G.

2017-11-01

Quantifying sulfur dioxide (SO2) in volcanic plumes is important for eruption predictions and public health. Ground-based remote sensing of spectral radiance of plumes contains information on the path-concentration of SO2. However, reliable inversion algorithms are needed to convert plume spectral radiance measurements into SO2 path-concentrations. Various techniques have been used for this purpose. Recent approaches have employed thermal infrared (TIR) imaging between 8 μm and 14 μm to provide two-dimensional mapping of plume SO2 path-concentration, using what might be described as "dual-view" techniques. In this case, the radiance (or its surrogate brightness temperature) is computed for portions of the image that correspond to the plume and compared with spectral radiance obtained for adjacent regions of the image that do not (i.e., "clear sky"). In this way, the contribution that the plume makes to the measured radiance can be isolated from the background atmospheric contribution, this residual signal being converted to an estimate of gas path-concentration via radiative transfer modeling. These dual-view approaches suffer from several issues, mainly the assumption of clear sky background conditions. At this time, the various inversion algorithms remain poorly validated. This paper makes two contributions. Firstly, it validates the aforementioned dual-view approaches, using hyperspectral TIR imaging data. Secondly, it introduces a new method to derive SO2 path-concentrations, which allows for single point SO2 path-concentration retrievals, suitable for hyperspectral imaging with clear or cloudy background conditions. The SO2 amenable lookup table algorithm (SO2-ALTA) uses the MODTRAN5 radiative transfer model to compute radiance for a variety (millions) of plume and atmospheric conditions. Rather than searching this lookup table to find the best fit for each measured spectrum, the lookup table was used to train a partial least square regression (PLSR) model. The coefficients of this model are used to invert measured radiance spectra to path-concentration on a pixel-by-pixel basis. In order to validate the algorithms, TIR hyperspectral measurements were carried out by measuring sky radiance when looking through gas cells filled with known amounts of SO2. SO2-ALTA was also tested on retrieving SO2 path-concentrations from the Kīlauea volcano, Hawai'i. For cloud-free conditions, all three techniques worked well. In cases where background clouds were present, then only SO2-ALTA was found to provide good results, but only under low atmospheric water vapor column amounts.

Calculation of Brown Carbon Optical Properties in the Fifth version Community Atmospheric Model (CAM5) and Validation with a Case Study in Kanpur, India

NASA Astrophysics Data System (ADS)

Xu, L.; Peng, Y.; Ram, K.

2017-12-01

The presence of absorbing component of organic carbon in atmospheric aerosols (Brown Carbon, BrC) has recently received much attention to the scientific community because of its absorbing nature, especially in the UV and Visible region. Attempts to account for BrC in radiative forcing calculations in climate model are rather scarce, primarily due to observational constrain as well as its incorporation in the model-based studies. Due to non-treatment of BrC in the off-line models, there exists a large discrepancy between model- and observational- based estimate of direct radiative effect of carbonaceous aerosols. In this study, we have included BrC absorption and optical characteristics in the fifth version of Community Atmospheric Model (CAM5) for the better understanding of radiative impact of BrC over northern India, also for improving the performance of aerosol radiative calculation in climate model. We have used the inputs of aerosol chemical composition measurements conducted at an urban site, Kanpur, in the Indo-Gangetic Plain (IGP) during 2007-2008 to construct the optical properties of BrC in CAM5 model. Model radiative simulations of sensitive tests showed good agreement with observations. Effects of varying imaginary part of BrC refractive index, relative mass ratio of BrC to organic aerosol in combination with core-shell mixing style of BrC with other anthropogenic aerosols are also analyzed for understanding BrC impact on simulated aerosol absorption in model.

Implications of GRACE Satellite Gravity Measurements for Diverse Hydrological Applications

NASA Astrophysics Data System (ADS)

Yirdaw-Zeleke, Sitotaw

Soil moisture plays a major role in the hydrologic water balance and is the basis for most hydrological models. It influences the partitioning of energy and moisture inputs at the land surface. Because of its importance, it has been used as a key variable for many hydrological studies such as flood forecasting, drought studies and the determination of groundwater recharge. Therefore, spatially distributed soil moisture with reasonable temporal resolution is considered a valuable source of information for hydrological model parameterization and validation. Unfortunately, soil moisture is difficult to measure and remains essentially unmeasured over spatial and temporal scales needed for a number of hydrological model applications. In 2002, the Gravity Recovery And Climate Experiment (GRACE) satellite platform was launched to measure, among other things, the gravitational field of the earth. Over its life span, these orbiting satellites have produced time series of mass changes of the earth-atmosphere system. The subsequent outcome of this, after integration over a number of years, is a time series of highly refined images of the earth's mass distribution. In addition to quantifying the static distribution of mass, the month-to-month variation in the earth's gravitational field are indicative of the integrated value of the subsurface total water storage for specific catchments. Utilization of these natural changes in the earth's gravitational field entails the transformation of the derived GRACE geopotential spherical harmonic coefficients into spatially varying time series estimates of total water storage. These remotely sensed basin total water storage estimates can be routinely validated against independent estimates of total water storage from an atmospheric-based water balance approach or from well calibrated macroscale hydrologic models. The hydrological relevance and implications of remotely estimated GRACE total water storage over poorly gauged, wetland-dominated watershed as well as over a deltaic region underlain by a thick sand aquifer in Western Canada are the focus of this thesis. The domain of the first case study was the Mackenzie River Basin wherein the GRACE total water storage estimates were successfully inter-compared and validated with the atmospheric based water balance. These were then used to assess the WAT-CLASS hydrological model estimates of total water storage. The outcome of this inter-comparison revealed the potential application of the GRACE-based approach for the closure of the hydrological water balance of the Mackenzie River Basin as well as a dependable source of data for the calibration of traditional hydrological models. The Mackenzie River Basin result led to a second case study where the GRACE-based total water storage was validated using storage estimated from the atmospheric-based water balance P--E computations in conjunction with the measured streamflow records for the Saskatchewan River Basin at its Grand Rapids outlet in Manitoba. The fallout from this comparison was then applied to the characterization of the Prairie-wide 2002/2003 drought enabling the development of a new drought index now known as the Total Storage Deficit Index (TSDI). This study demonstrated the potential application of the GRACE-based technique as a tool for drought characterization in the Canadian Prairies. Finally, the hydroinformatic approach based on the artificial neural network (ANN) enabled the downscaling of the groundwater component from the total water storage estimate from the remote sensing satellite, GRACE. This was subsequently explored as an alternate source of calibration and validation for a hydrological modeling application over the Assiniboine Delta Aquifer in Manitoba. Interestingly, a high correlation exists between the simulated groundwater storage from the coupled hydrological model, CLM-PF and the downscaled groundwater time series storage from the remote sensing satellite GRACE over this 4,000 km2 deltaic basin in Canada.

Development and Validation of Water Vapor Tracers as Diagnostics for the Atmospheric Hydrologic Cycle

NASA Technical Reports Server (NTRS)

Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

2000-01-01

Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. The formulation of the sources and sinks of tracer water is generally proportional to the prognostic water vapor variable. Because all water has been accounted for in tracers, the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The tracers have been implemented in a GEOS General Circulation Model (GCM) simulation consisting of several summer periods to determine the source regions of precipitation for the United States and India. The recycling of water and interannual variability of the sources of water will be examined. Potential uses in GCM sensitivity studies, predictability studies and data assimilation will be discussed.

On the interplay of gas dynamics and the electromagnetic field in an atmospheric Ar/H2 microwave plasma torch

NASA Astrophysics Data System (ADS)

Synek, Petr; Obrusník, Adam; Hübner, Simon; Nijdam, Sander; Zajíčková, Lenka

2015-04-01

A complementary simulation and experimental study of an atmospheric pressure microwave torch operating in pure argon or argon/hydrogen mixtures is presented. The modelling part describes a numerical model coupling the gas dynamics and mixing to the electromagnetic field simulations. Since the numerical model is not fully self-consistent and requires the electron density as an input, quite extensive spatially resolved Stark broadening measurements were performed for various gas compositions and input powers. In addition, the experimental part includes Rayleigh scattering measurements, which are used for the validation of the model. The paper comments on the changes in the gas temperature and hydrogen dissociation with the gas composition and input power, showing in particular that the dependence on the gas composition is relatively strong and non-monotonic. In addition, the work provides interesting insight into the plasma sustainment mechanism by showing that the power absorption profile in the plasma has two distinct maxima: one at the nozzle tip and one further upstream.

Multi-parameter Observations and Validation of Pre-earthquake Atmospheric Signals

NASA Astrophysics Data System (ADS)

Ouzounov, D.; Pulinets, S. A.; Hattori, K.; Mogi, T.; Kafatos, M.

2014-12-01

We are presenting the latest development in multi-sensors observations of short-term pre-earthquake phenomena preceding major earthquakes. We are exploring the potential of pre-seismic atmospheric and ionospheric signals to alert for large earthquakes. To achieve this, we start validating anomalous ionospheric /atmospheric signals in retrospective and prospective modes. The integrated satellite and terrestrial framework (ISTF) is our method for validation and is based on a joint analysis of several physical and environmental parameters (Satellite thermal infrared radiation (OLR), electron concentration in the ionosphere (GPS/TEC), VHF-bands radio waves, radon/ion activities, air temperature and seismicity patterns) that were found to be associated with earthquakes. The science rationale for multidisciplinary analysis is based on concept Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) [Pulinets and Ouzounov, 2011], which explains the synergy of different geospace processes and anomalous variations, usually named short-term pre-earthquake anomalies. Our validation processes consist in two steps: (1) A continuous retrospective analysis preformed over two different regions with high seismicity- Taiwan and Japan for 2003-2009 The retrospective tests (100+ major earthquakes, M>5.9, Taiwan and Japan) show OLR anomalous behavior before all of these events with no false negatives. False alarm ratio for false positives is less then 25%. (2) Prospective testing using multiple parameters with potential for M5.5+ events. The initial testing shows systematic appearance of atmospheric anomalies in advance (days) to the M5.5+ events for Taiwan and Japan (Honshu and Hokkaido areas). Our initial prospective results suggest that our approach show a systematic appearance of atmospheric anomalies, one to several days prior to the largest earthquakes That feature could be further studied and tested for advancing the multi-sensors detection of pre-earthquake atmospheric signals.

Constraining planetary atmospheric density: application of heuristic search algorithms to aerodynamic modeling of impact ejecta trajectories

NASA Astrophysics Data System (ADS)

Liu, Z. Y. C.; Shirzaei, M.

2015-12-01

Impact craters on the terrestrial planets are typically surrounded by a continuous ejecta blanket that the initial emplacement is via ballistic sedimentation. Following an impact event, a significant volume of material is ejected and falling debris surrounds the crater. Aerodynamics rule governs the flight path and determines the spatial distribution of these ejecta. Thus, for the planets with atmosphere, the preserved ejecta deposit directly recorded the interaction of ejecta and atmosphere at the time of impact. In this study, we develop a new framework to establish links between distribution of the ejecta, age of the impact and the properties of local atmosphere. Given the radial distance of the continuous ejecta extent from crater, an inverse aerodynamic modeling approach is employed to estimate the local atmospheric drags and density as well as the lift forces at the time of impact. Based on earlier studies, we incorporate reasonable value ranges for ejection angle, initial velocity, aerodynamic drag, and lift in the model. In order to solve the trajectory differential equations, obtain the best estimate of atmospheric density, and the associated uncertainties, genetic algorithm is applied. The method is validated using synthetic data sets as well as detailed maps of impact ejecta associated with five fresh martian and two lunar impact craters, with diameter of 20-50 m, 10-20 m, respectively. The estimated air density for martian carters range 0.014-0.028 kg/m3, consistent with the recent surface atmospheric density measurement of 0.015-0.020 kg/m3. This constancy indicates the robustness of the presented methodology. In the following, the inversion results for the lunar craters yield air density of 0.003-0.008 kg/m3, which suggest the inversion results are accurate to the second decimal place. This framework will be applied to older martian craters with preserved ejecta blankets, which expect to constrain the long-term evolution of martian atmosphere.

H20 and CH4 abundances under non-LTE conditions from MIPAS upper atmosphere measurements.

NASA Astrophysics Data System (ADS)

Koukouli, M. E.; Imk-Iaa Mipas/Envisat Team

Vertical profiles of water vapour and methane have been retrieved from measurements of the Earth's Upper Atmosphere made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the polar orbiting ENVISAT satellite. The spectral range targeted is 685-2410 cm-1 (4.1-14.6 μm) and the retrieval altitude range is ˜25-80 km. The Generic RAdiative traNsfer AnD non-LTE population Algorithm (GRANADA), jointly developed by IAA and IMK, has been used to analyse two days' worth of upper atmosphere orbits, from July 2002 and June 2003. The vertical profiles retrieved are compared and calibrated against other known water vapour experiments (e.g. HALOE) in the corresponding vertical and spacial co-locations. Global three-dimensional maps are also presented and validated against modelling results (e.g. Garcia and Solomon). The total hydrogen content of the Earth's middle atmosphere will also be investigated as means of identifying possible sinks or sources in the water vapour and methane day-night variability. A comprehensive systematic error analysis will complement the presentation of the results.

Effect of increasing CO2 on the terrestrial carbon cycle

PubMed Central

Schimel, David; Fisher, Joshua B.

2015-01-01

Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation. PMID:25548156

Scavenging of radioactive soluble gases from inhomogeneous atmosphere by evaporating rain droplets.

PubMed

Elperin, Tov; Fominykh, Andrew; Krasovitov, Boris

2015-05-01

We analyze effects of inhomogeneous concentration and temperature distributions in the atmosphere, rain droplet evaporation and radioactive decay of soluble gases on the rate of trace gas scavenging by rain. We employ a one-dimensional model of precipitation scavenging of radioactive soluble gaseous pollutants that is valid for small gradients and non-uniform initial altitudinal distributions of temperature and concentration in the atmosphere. We assume that conditions of equilibrium evaporation of rain droplets are fulfilled. It is demonstrated that transient altitudinal distribution of concentration under the influence of rain is determined by the linear wave equation that describes propagation of a scavenging wave front. The obtained equation is solved by the method of characteristics. Scavenging coefficients are calculated for wet removal of gaseous iodine-131 and tritiated water vapor (HTO) for the exponential initial distribution of trace gases concentration in the atmosphere and linear temperature distribution. Theoretical predictions of the dependence of the magnitude of the scavenging coefficient on rain intensity for tritiated water vapor are in good agreement with the available atmospheric measurements. Copyright © 2015 Elsevier Ltd. All rights reserved.

A New 1DVAR Retrieval for AMSR2 and GMI: Validation and Sensitivites

NASA Astrophysics Data System (ADS)

Duncan, D.; Kummerow, C. D.

2015-12-01

A new non-raining retrieval has been developed for microwave imagers and applied to the GMI and AMSR2 sensors. With the Community Radiative Transfer Model (CRTM) as the forward model for the physical retrieval, a 1-dimensional variational method finds the atmospheric state which minimizes the difference between observed and simulated brightness temperatures. A key innovation of the algorithm development is a method to calculate the sensor error covariance matrix that is specific to the forward model employed and includes off-diagonal elements, allowing the algorithm to handle various forward models and sensors with little cross-talk. The water vapor profile is resolved by way of empirical orthogonal functions (EOFs) and then summed to get total precipitable water (TPW). Validation of retrieved 10m wind speed, TPW, and sea surface temperature (SST) is performed via comparison with buoys and radiosondes as well as global models and other remotely sensed products. In addition to the validation, sensitivity experiments investigate the impact of ancillary data on the under-constrained retrieval, a concern for climate data records that strive to be independent of model biases. The introduction of model analysis data is found to aid the algorithm most at high frequency channels and affect TPW retrievals, whereas wind and cloud water retrievals show little effect from ingesting further ancillary data.

Model atmospheres for M (sub)dwarf stars. 1: The base model grid

NASA Technical Reports Server (NTRS)

Allard, France; Hauschildt, Peter H.

1995-01-01

We have calculated a grid of more than 700 model atmospheres valid for a wide range of parameters encompassing the coolest known M dwarfs, M subdwarfs, and brown dwarf candidates: 1500 less than or equal to T(sub eff) less than or equal to 4000 K, 3.5 less than or equal to log g less than or equal to 5.5, and -4.0 less than or equal to (M/H) less than or equal to +0.5. Our equation of state includes 105 molecules and up to 27 ionization stages of 39 elements. In the calculations of the base grid of model atmospheres presented here, we include over 300 molecular bands of four molecules (TiO, VO, CaH, FeH) in the JOLA approximation, the water opacity of Ludwig (1971), collision-induced opacities, b-f and f-f atomic processes, as well as about 2 million spectral lines selected from a list with more than 42 million atomic and 24 million molecular (H2, CH, NH, OH, MgH, SiH, C2, CN, CO, SiO) lines. High-resolution synthetic spectra are obtained using an opacity sampling method. The model atmospheres and spectra are calculated with the generalized stellar atmosphere code PHOENIX, assuming LTE, plane-parallel geometry, energy (radiative plus convective) conservation, and hydrostatic equilibrium. The model spectra give close agreement with observations of M dwarfs across a wide spectral range from the blue to the near-IR, with one notable exception: the fit to the water bands. We discuss several practical applications of our model grid, e.g., broadband colors derived from the synthetic spectra. In light of current efforts to identify genuine brown dwarfs, we also show how low-resolution spectra of cool dwarfs vary with surface gravity, and how the high-regulation line profile of the Li I resonance doublet depends on the Li abundance.

Choosing Meteorological Input for the Global Modeling Initiative Assessment of High Speed Aircraft

NASA Technical Reports Server (NTRS)

Douglas, A. R.; Prather, M. P.; Hall, T. M.; Strahan, S. E.; Rasch, P. J.; Sparling, L. C.; Coy, L.; Rodriquez, J. M.

1998-01-01

The Global Modeling Initiative (GMI) science team is developing a three dimensional chemistry and transport model (CTM) to be used in assessment of the atmospheric effects of aviation. Requirements are that this model be documented, be validated against observations, use a realistic atmospheric circulation, and contain numerical transport and photochemical modules representing atmospheric processes. The model must also retain computational efficiency to be tractable to use for multiple scenarios and sensitivity studies. To meet these requirements, a facility model concept was developed in which the different components of the CTM are evaluated separately. The first use of the GMI model will be to evaluate the impact of the exhaust of supersonic aircraft on the stratosphere. The assessment calculations will depend strongly on the wind and temperature fields used by the CTM. Three meteorological data sets for the stratosphere are available to GMI: the National Center for Atmospheric Research Community Climate Model (CCM2), the Goddard Earth Observing System Data Assimilation System (GEOS DAS), and the Goddard Institute for Space Studies general circulation model (GISS). Objective criteria were established by the GMI team to identify the data set which provides the best representation of the stratosphere. Simulations of gases with simple chemical control were chosen to test various aspects of model transport. The three meteorological data sets were evaluated and graded based on their ability to simulate these aspects of stratospheric measurements. This paper describes the criteria used in grading the meteorological fields. The meteorological data set which has the highest score and therefore was selected for GMI is CCM2. This type of objective model evaluation establishes a physical basis for interpretation of differences between models and observations. Further, the method provides a quantitative basis for defining model errors, for discriminating between different models, and for ready re-evaluation of improved models. These in turn will lead to a higher level of confidence in assessment calculations.

GPS Recovery of Daily Hydrologic and Atmospheric Mass Variation: A Methodology and Results From the Australian Continent

NASA Astrophysics Data System (ADS)

Han, Shin-Chan; Razeghi, S. Mahdiyeh

2017-11-01

We present a methodology to invert a regional set of vertical displacement data from Global Positioning System (GPS) to determine the surface mass redistribution. It is assumed that GPS deformation is a result of the Earth's elastic response to the surface mass load of hydrology, atmosphere, and/or ocean. We develop an algorithm to estimate the spectral information of displacements from "regional" GPS data through regional spherical (Slepian) basis functions and apply the load Love numbers to estimate the mass load. The same approach is applied to determine global mass changes from "global" geopotential change data of Gravity Recovery and Climate Experiment (GRACE). We rigorously examine all systematic errors caused by various truncations (spherical harmonic series and Slepian series) and the smoothing constraint applied to the GPS inversion. We demonstrate the technique by processing 16 years of daily vertical motions determined from 114 GPS stations in Australia. The GPS-inverted surface mass changes are validated against GRACE data, atmosphere and ocean models, and a land surface model. Seasonal and interannual terrestrial mass variations from GPS are in good agreement with GRACE data and the water storage models. The GPS recovery compares better with the water storage model around the smaller coastal basins than two different GRACE solutions. The submonthly mass changes from GPS provide meaningful results agreeing with atmospheric mass changes in central Australia. Finally, it is suggested to integrate GPS and GRACE data to draw a comprehensive picture of daily mass changes on different continents.

Validation of the Earth atmosphere models using the EUV solar occultation data from the CORONAS and PROBA 2 instruments

NASA Astrophysics Data System (ADS)

Slemzin, Vladimir; Kuzin, Sergey; Berghmans, David; Pertsov, Andrey; Dominique, Marie; Ulyanov, Artyom; Gaikovich, Konstantin

Absorption in the atmosphere below 500 km results in attenuation of the solar EUV flux, variation of its spectra and distortion of solar images acquired by solar EUV instruments operating on LEO satellites even on solar synchronous orbits. Occultation measurements are important for planning of solar observations from these satellites, and can be used for monitoring the upper atmosphere as well as for studying its response to the solar activity. We present the results of the occultation measurements of the solar EUV radiation obtained by the CORONAS-F/SPIRIT telescope at high solar activity (2002), by the CORONAS-Photon/TESIS telescope at low activity (2009), and by the SWAP telescope and LYRA radiometer onboard the PROBA 2 satellite at moderate activity (2010). The measured attenuation profiles and the retrieved linear extinction coefficients at the heights 200-500 km are compared with simulations by the NRLMSIS-00 and DTM2013 atmospheric models. It was shown that the results of simulations by the DTM2013 model are well agreed with the data of measurements at all stages of solar activity and in presence of the geomagnetic storm, whereas the results of the NRLMSISE-00 model significantly diverge from the measurements, in particular, at high and low activity. The research leading to these results has received funding from the European Union’s Seventh Programme for Research, Technological Development and Demonstration under Grant Agreement “eHeroes” (project No.284461, www.eheroes.eu).

Analytical Model for Estimating Terrestrial Cosmic Ray Fluxes Nearly Anytime and Anywhere in the World: Extension of PARMA/EXPACS.

PubMed

Sato, Tatsuhiko

2015-01-01

By extending our previously established model, here we present a new model called "PHITS-based Analytical Radiation Model in the Atmosphere (PARMA) version 3.0," which can instantaneously estimate terrestrial cosmic ray fluxes of neutrons, protons, ions with charge up to 28 (Ni), muons, electrons, positrons, and photons nearly anytime and anywhere in the Earth's atmosphere. The model comprises numerous analytical functions with parameters whose numerical values were fitted to reproduce the results of the extensive air shower (EAS) simulation performed by Particle and Heavy Ion Transport code System (PHITS). The accuracy of the EAS simulation was well verified using various experimental data, while that of PARMA3.0 was confirmed by the high R2 values of the fit. The models to be used for estimating radiation doses due to cosmic ray exposure, cosmic ray induced ionization rates, and count rates of neutron monitors were validated by investigating their capability to reproduce those quantities measured under various conditions. PARMA3.0 is available freely and is easy to use, as implemented in an open-access software program EXcel-based Program for Calculating Atmospheric Cosmic ray Spectrum (EXPACS). Because of these features, the new version of PARMA/EXPACS can be an important tool in various research fields such as geosciences, cosmic ray physics, and radiation research.

Analytical Model for Estimating Terrestrial Cosmic Ray Fluxes Nearly Anytime and Anywhere in the World: Extension of PARMA/EXPACS

PubMed Central

Sato, Tatsuhiko

2015-01-01

By extending our previously established model, here we present a new model called “PHITS-based Analytical Radiation Model in the Atmosphere (PARMA) version 3.0,” which can instantaneously estimate terrestrial cosmic ray fluxes of neutrons, protons, ions with charge up to 28 (Ni), muons, electrons, positrons, and photons nearly anytime and anywhere in the Earth’s atmosphere. The model comprises numerous analytical functions with parameters whose numerical values were fitted to reproduce the results of the extensive air shower (EAS) simulation performed by Particle and Heavy Ion Transport code System (PHITS). The accuracy of the EAS simulation was well verified using various experimental data, while that of PARMA3.0 was confirmed by the high R 2 values of the fit. The models to be used for estimating radiation doses due to cosmic ray exposure, cosmic ray induced ionization rates, and count rates of neutron monitors were validated by investigating their capability to reproduce those quantities measured under various conditions. PARMA3.0 is available freely and is easy to use, as implemented in an open-access software program EXcel-based Program for Calculating Atmospheric Cosmic ray Spectrum (EXPACS). Because of these features, the new version of PARMA/EXPACS can be an important tool in various research fields such as geosciences, cosmic ray physics, and radiation research. PMID:26674183

[Study on the modeling of earth-atmosphere coupling over rugged scenes for hyperspectral remote sensing].

PubMed

Zhao, Hui-Jie; Jiang, Cheng; Jia, Guo-Rui

2014-01-01

Adjacency effects may introduce errors in the quantitative applications of hyperspectral remote sensing, of which the significant item is the earth-atmosphere coupling radiance. However, the surrounding relief and shadow induce strong changes in hyperspectral images acquired from rugged terrain, which is not accurate to describe the spectral characteristics. Furthermore, the radiative coupling process between the earth and the atmosphere is more complex over the rugged scenes. In order to meet the requirements of real-time processing in data simulation, an equivalent reflectance of background was developed by taking into account the topography and the geometry between surroundings and targets based on the radiative transfer process. The contributions of the coupling to the signal at sensor level were then evaluated. This approach was integrated to the sensor-level radiance simulation model and then validated through simulating a set of actual radiance data. The results show that the visual effect of simulated images is consistent with that of observed images. It was also shown that the spectral similarity is improved over rugged scenes. In addition, the model precision is maintained at the same level over flat scenes.

Novel approximation of misalignment fading modeled by Beckmann distribution on free-space optical links.

PubMed

Boluda-Ruiz, Rubén; García-Zambrana, Antonio; Castillo-Vázquez, Carmen; Castillo-Vázquez, Beatriz

2016-10-03

A novel accurate and useful approximation of the well-known Beckmann distribution is presented here, which is used to model generalized pointing errors in the context of free-space optical (FSO) communication systems. We derive an approximate closed-form probability density function (PDF) for the composite gamma-gamma (GG) atmospheric turbulence with the pointing error model using the proposed approximation of the Beckmann distribution, which is valid for most practical terrestrial FSO links. This approximation takes into account the effect of the beam width, different jitters for the elevation and the horizontal displacement and the simultaneous effect of nonzero boresight errors for each axis at the receiver plane. Additionally, the proposed approximation allows us to delimit two different FSO scenarios. The first of them is when atmospheric turbulence is the dominant effect in relation to generalized pointing errors, and the second one when generalized pointing error is the dominant effect in relation to atmospheric turbulence. The second FSO scenario has not been studied in-depth by the research community. Moreover, the accuracy of the method is measured both visually and quantitatively using curve-fitting metrics. Simulation results are further included to confirm the analytical results.

Stochastic modeling for time series InSAR: with emphasis on atmospheric effects

NASA Astrophysics Data System (ADS)

Cao, Yunmeng; Li, Zhiwei; Wei, Jianchao; Hu, Jun; Duan, Meng; Feng, Guangcai

2018-02-01

Despite the many applications of time series interferometric synthetic aperture radar (TS-InSAR) techniques in geophysical problems, error analysis and assessment have been largely overlooked. Tropospheric propagation error is still the dominant error source of InSAR observations. However, the spatiotemporal variation of atmospheric effects is seldom considered in the present standard TS-InSAR techniques, such as persistent scatterer interferometry and small baseline subset interferometry. The failure to consider the stochastic properties of atmospheric effects not only affects the accuracy of the estimators, but also makes it difficult to assess the uncertainty of the final geophysical results. To address this issue, this paper proposes a network-based variance-covariance estimation method to model the spatiotemporal variation of tropospheric signals, and to estimate the temporal variance-covariance matrix of TS-InSAR observations. The constructed stochastic model is then incorporated into the TS-InSAR estimators both for parameters (e.g., deformation velocity, topography residual) estimation and uncertainty assessment. It is an incremental and positive improvement to the traditional weighted least squares methods to solve the multitemporal InSAR time series. The performance of the proposed method is validated by using both simulated and real datasets.

Photolysis Rate Coefficient Calculations in Support of SOLVE Campaign

NASA Technical Reports Server (NTRS)

Lloyd, Steven A.; Swartz, William H.

2001-01-01

The objectives for this SOLVE project were 3-fold. First, we sought to calculate a complete set of photolysis rate coefficients (j-values) for the campaign along the ER-2 and DC-8 flight tracks. En route to this goal, it would be necessary to develop a comprehensive set of input geophysical conditions (e.g., ozone profiles), derived from various climatological, aircraft, and remotely sensed datasets, in order to model the radiative transfer of the atmosphere accurately. These j-values would then need validation by comparison with flux-derived j-value measurements. The second objective was to analyze chemistry along back trajectories using the NASA/Goddard chemistry trajectory model initialized with measurements of trace atmospheric constituents. This modeling effort would provide insight into the completeness of current measurements and the chemistry of Arctic wintertime ozone loss. Finally, we sought to coordinate stellar occultation measurements of ozone (and thus ozone loss) during SOLVE using the Midcourse Space Experiment(MSX)/Ultraviolet and Visible Imagers and Spectrographic Imagers (UVISI) satellite instrument. Such measurements would determine ozone loss during the Arctic polar night and represent the first significant science application of space-based stellar occultation in the Earth's atmosphere.

Monitoring Orbital Precession of EO-1 Hyperion With Three Atmospheric Correction Models in the Libya-4 PICS

NASA Technical Reports Server (NTRS)

Neigh, Christopher S. R.; McCorkel, Joel; Campbell, Petya K. E.; Ong, Lawrence; Ly, Vuong; Landis, David; Middleton, Elizabeth M.

2016-01-01

Spaceborne spectrometers require spectral-temporal stability characterization to aid in validation of derived data products. Earth Observation 1 (EO-1) began orbital precession in 2011 after exhausting onboard fuel resources. In the Libya-4 pseudo-invariant calibration site (PICS), this resulted in a progressive shift from a mean local equatorial crossing time of approximately10:00 A.M. in 2011 to approximately 8:30 A.M. in late 2015. Here, we studied precession impacts to Hyperion surface reflectance products using three atmospheric correction approaches from 2004 to 2015. Combined difference estimates of surface reflectance were less than 5 percent in the visible near infrared (VNIR) and less than 10 percent for most of the shortwave infrared (SWIR). Combined coefficient of variation estimates in the VNIR ranged from 0.025 to 0.095, and in the SWIR it ranged from 0.025 to 0.06, excluding bands near atmospheric absorption features. Reflectances produced with different atmospheric models were correlated (R squared) in VNIR from 0.25 to 0.94 and in SWIR from 0.12 to 0.88 (p value (calculated probability) less than 0.01). The uncertainties in all the models increased with a terrain slope up to 15 degrees and selecting dune flats could reduce errors. We conclude that these data remain a valuable resource over this period for sensor intercalibration despite orbital decay.

Vehicle license plate recognition in dense fog based on improved atmospheric scattering model

NASA Astrophysics Data System (ADS)

Tang, Chunming; Lin, Jun; Chen, Chunkai; Dong, Yancheng

2018-04-01

An effective method based on improved atmospheric scattering model is proposed in this paper to handle the problem of the vehicle license plate location and recognition in dense fog. Dense fog detection is performed firstly by the top-hat transformation and the vertical edge detection, and the moving vehicle image is separated from the traffic video image. After the vehicle image is decomposed into two layers: structure and texture layers, the glow layer is separated from the structure layer to get the background layer. Followed by performing the mean-pooling and the bicubic interpolation algorithm, the atmospheric light map of the background layer can be predicted, meanwhile the transmission of the background layer is estimated through the grayed glow layer, whose gray value is altered by linear mapping. Then, according to the improved atmospheric scattering model, the final restored image can be obtained by fusing the restored background layer and the optimized texture layer. License plate location is performed secondly by a series of morphological operations, connected domain analysis and various validations. Characters extraction is achieved according to the projection. Finally, an offline trained pattern classifier of hybrid discriminative restricted boltzmann machines (HDRBM) is applied to recognize the characters. Experimental results on thorough data sets are reported to demonstrate that the proposed method can achieve high recognition accuracy and works robustly in the dense fog traffic environment during 24h or one day.

The 2006 Cape Canaveral Air Force Station Range Reference Atmosphere Model Validation Study and Sensitivity Analysis to the National Aeronautics and Space Administration's Space Shuttle

NASA Technical Reports Server (NTRS)

Decker, Ryan; Burns, Lee; Merry, Carl; Harrington, Brian

2008-01-01

NASA's Space Shuttle utilizes atmospheric thermodynamic properties to evaluate structural dynamics and vehicle flight performance impacts by the atmosphere during ascent. Statistical characteristics of atmospheric thermodynamic properties at Kennedy Space Center (KSC) used in Space. Shuttle Vehicle assessments are contained in the Cape Canaveral Air Force Station (CCAFS) Range Reference Atmosphere (RRA) Database. Database contains tabulations for monthly and annual means (mu), standard deviations (sigma) and skewness of wind and thermodynamic variables. Wind, Thermodynamic, Humidity and Hydrostatic parameters 1 km resolution interval from 0-30 km 2 km resolution interval 30-70 km Multiple revisions of the CCAFS RRA database have been developed since initial RRA published in 1963. 1971, 1983, 2006 Space Shuttle program utilized 1983 version for use in deriving "hot" and "cold" atmospheres, atmospheric density dispersions for use in vehicle certification analyses and selection of atmospheric thermodynamic profiles for use in vehicle ascent design and certification analyses. During STS-114 launch preparations in July 2005 atmospheric density observations between 50-80 kft exceeded density limits used for aerodynamic ascent heating constraints in vehicle certification analyses. Mission specific analyses were conducted and concluded that the density bias resulted in small changes to heating rates and integrated heat loading on the vehicle. In 2001, the Air Force Combat Climatology Center began developing an updated RRA for CCAFS.

Marli: Mars Lidar for Global Wind Profiles and Aerosol Profiles from Orbit

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Guzewich, S. D.; Smith, M. D.; Riris, H.; Sun, X.; Gentry, B. M.; Yu, A.; Allan, G. R.

2016-01-01

The Mars Exploration Analysis Group's Next Orbiter Science Analysis Group (NEXSAG) has recently identified atmospheric wind measurements as one of 5 top compelling science objectives for a future Mars orbiter. To date, only isolated lander observations of martian winds exist. Winds are the key variable to understand atmospheric transport and answer fundamental questions about the three primary cycles of the martian climate: CO2, H2O, and dust. However, the direct lack of observations and imprecise and indirect inferences from temperature observations leave many basic questions about the atmospheric circulation unanswered. In addition to addressing high priority science questions, direct wind observations from orbit would help validate 3D general circulation models (GCMs) while also providing key input to atmospheric reanalyses. The dust and CO2 cycles on Mars are partially coupled and their influences on the atmospheric circulation modify the global wind field. Dust absorbs solar infrared radiation and its variable spatial distribution forces changes in the atmospheric temperature and wind fields. Thus it is important to simultaneously measure the height-resolved wind and dust profiles. MARLI provides a unique capability to observe these variables continuously, day and night, from orbit.

Controlled meteorological (CMET) balloon profiling of the Arctic atmospheric boundary layer around Spitsbergen compared to a mesoscale model

NASA Astrophysics Data System (ADS)

Roberts, T. J.; Dütsch, M.; Hole, L. R.; Voss, P. B.

2015-10-01

Observations from CMET (Controlled Meteorological) balloons are analyzed in combination with mesoscale model simulations to provide insights into tropospheric meteorological conditions (temperature, humidity, wind-speed) around Svalbard, European High Arctic. Five Controlled Meteorological (CMET) balloons were launched from Ny-Ålesund in Svalbard over 5-12 May 2011, and measured vertical atmospheric profiles above Spitsbergen Island and over coastal areas to both the east and west. One notable CMET flight achieved a suite of 18 continuous soundings that probed the Arctic marine boundary layer over a period of more than 10 h. The CMET profiles are compared to simulations using the Weather Research and Forecasting (WRF) model using nested grids and three different boundary layer schemes. Variability between the three model schemes was typically smaller than the discrepancies between the model runs and the observations. Over Spitsbergen, the CMET flights identified temperature inversions and low-level jets (LLJ) that were not captured by the model. Nevertheless, the model largely reproduced time-series obtained from the Ny-Ålesund meteorological station, with exception of surface winds during the LLJ. Over sea-ice east of Svalbard the model underestimated potential temperature and overestimated wind-speed compared to the CMET observations. This is most likely due to the full sea-ice coverage assumed by the model, and consequent underestimation of ocean-atmosphere exchange in the presence of leads or fractional coverage. The suite of continuous CMET soundings over a sea-ice free region to the northwest of Svalbard are analysed spatially and temporally, and compared to the model. The observed along-flight daytime increase in relative humidity is interpreted in terms of the diurnal cycle, and in the context of marine and terrestrial air-mass influences. Analysis of the balloon trajectory during the CMET soundings identifies strong wind-shear, with a low-level channeled flow. The study highlights the challenges of modelling the Arctic atmosphere, especially in coastal zones with varying topography, sea-ice and surface conditions. In this context, CMET balloons provide a valuable technology for profiling the free atmosphere and boundary layer in remote regions where few other observations are available for model validation.

Doppler lidar investigation of wind turbine wake characteristics and atmospheric turbulence under different surface roughness.

PubMed

Zhai, Xiaochun; Wu, Songhua; Liu, Bingyi

2017-06-12

Four field experiments based on Pulsed Coherent Doppler Lidar with different surface roughness have been carried out in 2013-2015 to study the turbulent wind field in the vicinity of operating wind turbine in the onshore and offshore wind parks. The turbulence characteristics in ambient atmosphere and wake area was analyzed using transverse structure function based on Plane Position Indicator scanning mode. An automatic wake processing procedure was developed to determine the wake velocity deficit by considering the effect of ambient velocity disturbance and wake meandering with the mean wind direction. It is found that the turbine wake obviously enhances the atmospheric turbulence mixing, and the difference in the correlation of turbulence parameters under different surface roughness is significant. The dependence of wake parameters including the wake velocity deficit and wake length on wind velocity and turbulence intensity are analyzed and compared with other studies, which validates the empirical model and simulation of a turbine wake for various atmosphere conditions.

Satellite Sounder Observations of Contrasting Tropospheric Moisture Transport Regimes: Saharan Air Layers, Hadley Cells, and Atmospheric Rivers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nalli, Nicholas R.; Barnet, Christopher D.; Reale, Tony

This paper examines the performance of satellite sounder atmospheric vertical moisture proles (AVMP) under tropospheric conditions encompassing moisture contrasts driven by convection and advection transport mechanisms, specifically Atlantic Ocean Saharan air layers (SALs) and Pacific Ocean moisture conveyer belts (MCBs) commonly referred to as atmospheric rivers (ARs), both of these being mesoscale to synoptic meteorological phenomena within the vicinity of subtropical Hadley subsidence zones. Operational AVMP environmental data records retrieved from the Suomi National Polar-orbiting Partnership (SNPP) NOAA-Unique Combined Atmospheric Processing System (NUCAPS) are collocated with dedicated radiosonde observations (RAOBs) obtained from ocean-based intensive field campaigns; these RAOBs provide uniquelymore » independent correlative truth data not assimilated into numerical weather prediction models for satellite sounder validation over open ocean. Using these marine-based data, we empirically assess the performance of the operational NUCAPS AVMP product for detecting and resolving these tropospheric moisture features over otherwise RAOB-sparse regions.« less

Distribution of apparent activation energy counterparts during thermo - And thermo-oxidative degradation of Aronia melanocarpa (black chokeberry).

PubMed

Janković, Bojan; Marinović-Cincović, Milena; Janković, Marija

2017-09-01

Kinetics of degradation for Aronia melanocarpa fresh fruits in argon and air atmospheres were investigated. The investigation was based on probability distributions of apparent activation energy of counterparts (ε a ). Isoconversional analysis results indicated that the degradation process in an inert atmosphere was governed by decomposition reactions of esterified compounds. Also, based on same kinetics approach, it was assumed that in an air atmosphere, the primary compound in degradation pathways could be anthocyanins, which undergo rapid chemical reactions. A new model of reactivity demonstrated that, under inert atmospheres, expectation values for ε a occured at levels of statistical probability. These values corresponded to decomposition processes in which polyphenolic compounds might be involved. ε a values obeyed laws of binomial distribution. It was established that, for thermo-oxidative degradation, Poisson distribution represented a very successful approximation for ε a values where there was additional mechanistic complexity and the binomial distribution was no longer valid. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Description and Validation of a Computationally-Efficient CH4-CO-OH (ECCOHv1.01) Chemistry Module for 3D Model Applications

NASA Technical Reports Server (NTRS)

Elshorbany, Yasin F.; Duncan, Bryan N.; Strode, Sarah A.; Wang, James S.; Kouatchou, Jules

2016-01-01

We present the Efficient CH4-CO-OH (ECCOH) chemistry module that allows for the simulation of the methane, carbon monoxide, and hydroxyl radical (CH4-CO- OH) system, within a chemistry climate model, carbon cycle model, or Earth system model. The computational efficiency of the module allows many multi-decadal sensitivity simulations of the CH4-CO-OH system, which primarily determines the global atmospheric oxidizing capacity. This capability is important for capturing the nonlinear feedbacks of the CH4-CO-OH system and understanding the perturbations to methane, CO, and OH, and the concomitant impacts on climate. We implemented the ECCOH chemistry module in the NASA GEOS-5 atmospheric global circulation model (AGCM), performed multiple sensitivity simulations of the CH4-CO-OH system over 2 decades, and evaluated the model output with surface and satellite data sets of methane and CO. The favorable comparison of output from the ECCOH chemistry module (as configured in the GEOS- 5 AGCM) with observations demonstrates the fidelity of the module for use in scientific research.

CALIPSO Satellite Lidar Identification Of Elevated Dust Over Australia Compared With Air Quality Model PM60 Forecasts

NASA Technical Reports Server (NTRS)

Young, Stuart A.; Vaughan, Mark; Omar, Ali; Liu, Zhaoyan; Lee, Sunhee; Hu, Youngxiang; Cope, Martin

2008-01-01

Global measurements of the vertical distribution of clouds and aerosols have been recorded by the lidar on board the CALIPSO (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) satellite since June 2006. Such extensive, height-resolved measurements provide a rare and valuable opportunity for developing, testing and validating various atmospheric models, including global climate, numerical weather prediction, chemical transport and air quality models. Here we report on the initial results of an investigation into the performance of the Australian Air Quality Forecast System (AAQFS) model in forecasting the distribution of elevated dust over the Australian region. The model forecasts of PM60 dust distribution are compared with the CALIPSO lidar Vertical Feature Mask (VFM) data product. The VFM classifies contiguous atmospheric regions of enhanced backscatter as either cloud or aerosols. Aerosols are further classified into six subtypes. By comparing forecast PM60 concentration profiles to the spatial distribution of dust reported in the CALIPSO VFM, we can assess the model s ability to predict the occurrence and the vertical and horizontal extents of dust events within the study area.

Double-pulse 2-μm integrated path differential absorption lidar airborne validation for atmospheric carbon dioxide measurement.

PubMed

Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Remus, Ruben; Ismail, Syed

2016-05-20

Field experiments were conducted to test and evaluate the initial atmospheric carbon dioxide (CO₂) measurement capability of airborne, high-energy, double-pulsed, 2-μm integrated path differential absorption (IPDA) lidar. This IPDA was designed, integrated, and operated at the NASA Langley Research Center on-board the NASA B-200 aircraft. The IPDA was tuned to the CO₂ strong absorption line at 2050.9670 nm, which is the optimum for lower tropospheric weighted column measurements. Flights were conducted over land and ocean under different conditions. The first validation experiments of the IPDA for atmospheric CO₂ remote sensing, focusing on low surface reflectivity oceanic surface returns during full day background conditions, are presented. In these experiments, the IPDA measurements were validated by comparison to airborne flask air-sampling measurements conducted by the NOAA Earth System Research Laboratory. IPDA performance modeling was conducted to evaluate measurement sensitivity and bias errors. The IPDA signals and their variation with altitude compare well with predicted model results. In addition, off-off-line testing was conducted, with fixed instrument settings, to evaluate the IPDA systematic and random errors. Analysis shows an altitude-independent differential optical depth offset of 0.0769. Optical depth measurement uncertainty of 0.0918 compares well with the predicted value of 0.0761. IPDA CO₂ column measurement compares well with model-driven, near-simultaneous air-sampling measurements from the NOAA aircraft at different altitudes. With a 10-s shot average, CO₂ differential optical depth measurement of 1.0054±0.0103 was retrieved from a 6-km altitude and a 4-GHz on-line operation. As compared to CO₂ weighted-average column dry-air volume mixing ratio of 404.08 ppm, derived from air sampling, IPDA measurement resulted in a value of 405.22±4.15  ppm with 1.02% uncertainty and 0.28% additional bias. Sensitivity analysis of environmental systematic errors correlates the additional bias to water vapor. IPDA ranging resulted in a measurement uncertainty of <3  m.

Emulation of rocket trajectory based on a six degree of freedom model

NASA Astrophysics Data System (ADS)

Zhang, Wenpeng; Li, Fan; Wu, Zhong; Li, Rong

2008-10-01

In this paper, a 6-DOF motion mathematical model is discussed. It is consisted of body dynamics and kinematics block, aero dynamics block and atmosphere block. Based on Simulink, the whole rocket trajectory mathematical model is developed. In this model, dynamic system simulation becomes easy and visual. The method of modularization design gives more convenience to transplant. At last, relevant data is given to be validated by Monte Carlo means. Simulation results show that the flight trajectory of the rocket can be simulated preferably by means of this model, and it also supplies a necessary simulating tool for the development of control system.

Using in-situ observations of atmospheric water vapor isotopes to benchmark and isotope-enabled General Circulation Models and improve ice core paleo-climate reconstruction

NASA Astrophysics Data System (ADS)

Steen-Larsen, Hans Christian; Sveinbjörnsdottir, Arny; Masson-Delmotte, Valerie; Werner, Martin; Risi, Camille; Yoshimura, Kei

2016-04-01

We have since 2010 carried out in-situ continuous water vapor isotope observations on top of the Greenland Ice Sheet (3 seasons at NEEM), in Svalbard (1 year), in Iceland (4 years), in Bermuda (4 years). The expansive dataset containing high accuracy and precision measurements of δ18O, δD, and the d-excess allow us to validate and benchmark the treatment of the atmospheric hydrological cycle's processes in General Circulation Models using simulations nudged to reanalysis products. Recent findings from both Antarctica and Greenland have documented strong interaction between the snow surface isotopes and the near surface atmospheric water vapor isotopes on diurnal to synoptic time scales. In fact, it has been shown that the snow surface isotopes take up the synoptic driven atmospheric water vapor isotopic signal in-between precipitation events, erasing the precipitation isotope signal in the surface snow. This highlights the importance of using General or Regional Climate Models, which accurately are able to simulate the atmospheric water vapor isotopic composition, to understand and interpret the ice core isotope signal. With this in mind we have used three isotope-enabled General Circulation Models (isoGSM, ECHAM5-wiso, and LMDZiso) nudged to reanalysis products. We have compared the simulations of daily mean isotope values directly with our in-situ observations. This has allowed us to characterize the variability of the isotopic composition in the models and compared it to our observations. We have specifically focused on the d-excess in order to characterize why both the mean and the variability is significantly lower than our observations. We argue that using water vapor isotopes to benchmark General Circulation Models offers an excellent tool for improving the treatment and parameterization of the atmospheric hydrological cycle. Recent studies have documented a very large inter-model dispersion in the treatment of the Arctic water cycle under a future global warming and greenhouse gas emission scenario. Our results call for action to create an international pan-Arctic monitoring water vapor isotope network in order to improve future projections of Arctic climate.

The water balance of the urban Salt Lake Valley: a multiple-box model validated by observations

NASA Astrophysics Data System (ADS)

Stwertka, C.; Strong, C.

2012-12-01

A main focus of the recently awarded National Science Foundation (NSF) EPSCoR Track-1 research project "innovative Urban Transitions and Arid-region Hydro-sustainability (iUTAH)" is to quantify the primary components of the water balance for the Wasatch region, and to evaluate their sensitivity to climate change and projected urban development. Building on the multiple-box model that we developed and validated for carbon dioxide (Strong et al 2011), mass balance equations for water in the atmosphere and surface are incorporated into the modeling framework. The model is used to determine how surface fluxes, ground-water transport, biological fluxes, and meteorological processes regulate water cycling within and around the urban Salt Lake Valley. The model is used to evaluate the hypotheses that increased water demand associated with urban growth in Salt Lake Valley will (1) elevate sensitivity to projected climate variability and (2) motivate more attentive management of urban water use and evaporative fluxes.

Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

2006-01-01

The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

Hydrodynamic escape from planetary atmospheres

NASA Astrophysics Data System (ADS)

Tian, Feng

Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early Earth's atmosphere. Simulations show that hydrodynamic escape of nitrogen from Pluto is able to remove a ~3 km layer of ice over the age of the solar system. The escape flux of neutral nitrogen may interact with the solar wind at Pluto's orbit and may be detected by the New Horizon mission.

What GRACE/GRACE-FO satellite gravity may tell about the atmosphere (and what not)

NASA Astrophysics Data System (ADS)

Eicker, Annette; Springer, Anne; Hense, Andreas; Panet, Isabelle; Kusche, Jürgen

2017-04-01

In this presentation we would like to discuss the present benefit and future potential of satellite gravity observations, as obtained from the satellite mission GRACE and its successor GRACE-Follow-On (GRACE-FO), for studying the atmospheric water cycle. In the first part of the presentation, we will show recent results of using GRACE to constrain atmospheric water budgets. GRACE-derived water storage changes (in combination with observed runoff) can be used to solve for the vertical water flux deficit of precipitation (P) minus evapotranspiration (E), which links the terrestrial and the atmospheric water balance equations. This relates gravity change to moisture flux divergence and water vapor change and thus provides, in principle, a link between GRACE/GRACE-FO and (area-averaged) GNSS integrated water vapor observations that may be exploited in the future. We will show that such an independent estimate of P minus E can be used to constrain land-atmosphere fluxes from monthly time scales to decadal trends and even provides meaningful flux information down to daily time steps. In the second part of the presentation, we would like to give an outlook towards the potential of using satellite gravity data directly for the estimation of atmospheric water mass changes. On the basis of ERA-Interim data, we provide a first assessment which suggests that an anticipated future double-pair gravity mission with enhanced temporal and spatial resolution would be sensitive to 'feeling' atmospheric water mass (water vapor) variations. However, whether these (faster) variations could be separated from dry air mass variations through modeling needs to be investigated. If possible, this would offer a completely new tool for validating atmospheric analyses and for improving engergy and mass budgets in models.

Characterizing the ozone formation potential of agricultural sources in California's San Joaquin Valley: A computational and experimental approach

NASA Astrophysics Data System (ADS)

Howard, Cody Jerome

The global pattern of expanding urban centers and increasing agricultural intensity is leading to more frequent interactions between air pollution emissions from urban and agricultural sources. The confluence of these emissions that traditionally have been separated by hundreds of kilometers is creating new air quality challenges in numerous regions across the United States. An area of particular interest is California's San Joaquin Valley (SJV), which has an agricultural output higher than many countries, a rapidly expanding human population, and ozone concentrations that are already higher than many dense urban areas. New regulations in the SJV restrict emissions of reactive organic gases (ROG) from animal sources in an attempt to meet Federal and State ozone standards designed to protect human health. A transportable "smog" chamber was developed and tested to directly measure the ozone formation potential of a variety of agricultural emissions in representative urban and rural atmospheres. After validation of the experimental procedure, four animal types were examined: beef cattle, dairy cattle, swine, and poultry, as well as six commonly used animal feeds: cereal silage (wheat grain and oat grain), alfalfa silage, corn silage, high moisture ground corn, almond shells, almond hulls, and total mixed ration. The emitted ROG composition was also measured so that the theoretical incremental reactivity could be calculated for a variety of atmospheres and directly compared with the measured ozone formation potential (OFP) under the experimental conditions. A computational model was created based on a modified form of the Caltech Atmospheric Chemistry Mechanism and validated against experimental results. After validation, the computational model was used to predict OFP across a range of NOx and ROG concentrations. The ROG OFP measurements combined with adjusted agricultural ROG emissions inventory estimates were used to predict the actual ozone production in the SJV attributed to the various agricultural sources.

Stennis Space Center Verification and Validation Capabilities

NASA Technical Reports Server (NTRS)

O'Neal, Duane; Daehler, Erik

2006-01-01

Topics covered include: Spatial Response; Reflectance Radiometry; Positional Accuracy; Stationary Atmospheric Monitoring; Laboratory Calibration; Thermal Radiometry; Hyperspectral Radiometry; and Portable Atmospheric Monitoring.

Testing the regionalization of a SVAT model for a region with high observation density

NASA Astrophysics Data System (ADS)

Eiermann, Sven; Thies, Boris; Bendix, Jörg

2014-05-01

The variable soil moisture is an important quantity in weather and climate investigations, because it has an essential influence on the energy exchange between the land surface and the atmosphere. However the recording of soil moisture in high spatio-temporal resolution is problematic. The planned Tandem-L mission of the German Aerospace Center (DLR) with an innovative L-band radar on board provides the opportunity to get daily soil moisture data at a spatial resolution of 50 meters. Within the Helmholtz Alliance Remote Sensing and Earth System Dynamics this data is planned to be used to regionalize a Soil Vegetation Atmosphere Transfer Model, in order to analyze the energy flux and the gas exchange and to improve the prediction of the water exchange between soil, vegetation and atmosphere. As investigation areas selected regions of the TERENO (TERrestrial ENviromental Observatoria) test sites and, later on, a region in South Ecuador will be used, for which data for the model initialization and validation are available. The reason for testing the method for the TERENO test sites first is the good data basis as a result of the already established high observation density there. The poster will present the methods being used for the model adaptation for the TERENO test sites and discuss the improvements achieved by these methods.

Estimation of the time-dependent radioactive source-term from the Fukushima nuclear power plant accident using atmospheric transport modelling

NASA Astrophysics Data System (ADS)

Schoeppner, M.; Plastino, W.; Budano, A.; De Vincenzi, M.; Ruggieri, F.

2012-04-01

Several nuclear reactors at the Fukushima Dai-ichi power plant have been severely damaged from the Tōhoku earthquake and the subsequent tsunami in March 2011. Due to the extremely difficult on-site situation it has been not been possible to directly determine the emissions of radioactive material. However, during the following days and weeks radionuclides of 137-Caesium and 131-Iodine (amongst others) were detected at monitoring stations throughout the world. Atmospheric transport models are able to simulate the worldwide dispersion of particles accordant to location, time and meteorological conditions following the release. The Lagrangian atmospheric transport model Flexpart is used by many authorities and has been proven to make valid predictions in this regard. The Flexpart software has first has been ported to a local cluster computer at the Grid Lab of INFN and Department of Physics of University of Roma Tre (Rome, Italy) and subsequently also to the European Mediterranean Grid (EUMEDGRID). Due to this computing power being available it has been possible to simulate the transport of particles originating from the Fukushima Dai-ichi plant site. Using the time series of the sampled concentration data and the assumption that the Fukushima accident was the only source of these radionuclides, it has been possible to estimate the time-dependent source-term for fourteen days following the accident using the atmospheric transport model. A reasonable agreement has been obtained between the modelling results and the estimated radionuclide release rates from the Fukushima accident.

Modeling of gravitational separation using the NIES global atmospheric tracer transport model

NASA Astrophysics Data System (ADS)

Belikov, D.; Ishidoya, S.; Sugawara, S.; Maksyutov, S. S.; Hasebe, F.

2017-12-01

The existence of gravitational separation (separation of atmospheric molecules depending on their molar masses) in the stratosphere was confirmed both experimentally from high-precision measurements of the isotopic ratios of N2, O2, Ar (Ishidoya et al., ACP, 2008), and theoretically by numerical simulations using the 2-dimensional model of the middle atmosphere (SOCRATES) (Ishidoya et al., ACP, 2013). It was also shown, that the gravitational separation, as well as their relationship with age of air, is usable as a new indicator of long-term changes in the Brewer-Dobson Circulation (BDC).For more detailed examination of the relationship between gravitational separation and the stratospheric circulation, we used the NIES (National Institute for Environmental Studies) three-dimensional global atmospheric tracer transport model with molecular diffusivity parameterization. The NIES transport model uses a flexible hybrid sigma-isentropic vertical coordinate, in which a vertical transport in the stratosphere was controlled by the heating rate from reanalysis. The simulated gravitational separation and age of air are validated through comparison with observations carried out using a balloon-borne cryogenic air sampler over Kiruna (68°N, 21°E), Sweden, Sanriku (39°N, 142°E) and Taiki (43°N, 143°E), Japan, Syowa Station (69°S, 39°E), Antarctica for 1995-2010.Our further study is an analysis of gravitational separation in respect of the major stratospheric processes including variabilities/changes in association with quasi-biennial oscillation, Asian summer monsoon, Sudden Stratospheric Warming events, acceleration of the BDC due to global warming.

ECHMERIT: A new on-line global mercury-chemistry model

NASA Astrophysics Data System (ADS)

Jung, G.; Hedgecock, I. M.; Pirrone, N.

2009-04-01

Mercury is a volatile metal, that is of concern because when deposited and transformed to methylmercury accumulates within the food-web. Due to the long lifetime of elemental mercury, which is the dominant fraction of mercury species in the atmosphere, mercury is prone to long-range transport and therefore distributed over the globe, transported and hence deposited even in regions far from anthropogenic emission sources. Mercury is released to the atmosphere from a variety of natural and anthropogenic sources, in elementary and oxidised forms, and as particulate mercury. It is then transported, but also transformed chemically in the gaseous phase, as well as in aqueous phase within cloud and rain droplets. Mercury (particularly its oxidised forms) is removed from the atmosphere though wet and dry deposition processes, a large fraction of deposited mercury is, after chemical or biological reduction, re-emitted to the atmosphere as elementary mercury. To investigate mercury chemistry and transport processes on the global scale, the new, global model ECHMERIT has been developed. ECHMERIT simulates meteorology, transport, deposition, photolysis and chemistry on-line. The general circulation model on which ECHMERIT is based is ECHAM5. Sophisticated chemical modules have been implemented, including gas phase chemistry based on the CBM-Z chemistry mechanism, as well as aqueous phase chemistry, both of which have been adapted to include Hg chemistry and Hg species gas-droplet mass transfer. ECHMERIT uses the fast-J photolysis routine. State-of-the-art procedures simulating wet and dry deposition and emissions were adapted and included in the model as well. An overview of the model structure, development, validation and sensitivity studies is presented.

Integrated Water Vapour Retrieval From Irish GPS Network: Results From Validation With Radiosondes And Microwave Profiler And Assimilation Into HIRLAM 7.2 Operational Forecasting Model

NASA Astrophysics Data System (ADS)

Hanafin, J. A.; Whelan, E.; McGrath, R.; Jennings, S. G.; O'Dowd, C.

2009-12-01

Retrieval of atmospheric integrated water vapour (IWV) from ground-based GPS receivers and provision of this data product for meteorological applications is the focus of the European EUMETNET GPS water vapour programme. The results presented here are the first from a project to provide such information about the state of the atmosphere around Ireland for climate monitoring and improved numerical weather prediction. Two geodetic reference GPS receivers have been deployed at Valentia Observatory in Co. Kerry and Mace Head Atmospheric Research Station in Co. Galway, Ireland. A system to retrieve column-integrated atmospheric water vapour from the data they provide has been developed. Data quality has been assessed using co-located radiosondes at Valentia and observations from a microwave profiling radiometer at Mace Head. Results from the data processing and comparisons with independent observations will be presented. Water vapour retrievals from such sensors can provide good quality observations at hourly intervals of this essential climate variable for assimilation into numerical nowcast and forecast systems. Previous studies have shown that using these data to constrain initial model conditions can improve the accuracy of precipitation forecasts, particularly for heavy rainfall. The current operational forecast model in use at Met Éireann for the region is the new version 7.2 HIRLAM (High-Resolution Limited Area Model). The effects on the forecast for Ireland have been evaluated by assimilating the data into 48-hour forecast runs of this model and results of this study will also be presented.

Directivity of a Sparse Array in the Presence of Atmospheric-Induced Phase Fluctuations for Deep Space Communications

NASA Technical Reports Server (NTRS)

Nessel, James A.; Acosta, Robert J.

2010-01-01

Widely distributed (sparse) ground-based arrays have been utilized for decades in the radio science community for imaging celestial objects, but have only recently become an option for deep space communications applications with the advent of the proposed Next Generation Deep Space Network (DSN) array. But whereas in astronomical imaging, observations (receive-mode only) are made on the order of minutes to hours and atmospheric-induced aberrations can be mostly corrected for in post-processing, communications applications require transmit capabilities and real-time corrections over time scales as short as fractions of a second. This presents an unavoidable problem with the use of sparse arrays for deep space communications at Ka-band which has yet to be successfully resolved, particularly for uplink arraying. In this paper, an analysis of the performance of a sparse antenna array, in terms of its directivity, is performed to derive a closed form solution to the expected array loss in the presence of atmospheric-induced phase fluctuations. The theoretical derivation for array directivity degradation is validated with interferometric measurements for a two-element array taken at Goldstone, California. With the validity of the model established, an arbitrary 27-element array geometry is defined at Goldstone, California, to ascertain its performance in the presence of phase fluctuations. It is concluded that a combination of compact array geometry and atmospheric compensation is necessary to ensure high levels of availability.

Is Ecosystem-Atmosphere Observation in Long-Term Networks actually Science?

NASA Astrophysics Data System (ADS)

Schmid, H. P. E.

2015-12-01

Science uses observations to build knowledge by testable explanations and predictions. The "scientific method" requires controlled systematic observation to examine questions, hypotheses and predictions. Thus, enquiry along the scientific method responds to questions of the type "what if …?" In contrast, long-term observation programs follow a different strategy: we commonly take great care to minimize our influence on the environment of our measurements, with the aim to maximize their external validity. We observe what we think are key variables for ecosystem-atmosphere exchange and ask questions such as "what happens next?" or "how did this happen?" This apparent deviation from the scientific method begs the question whether any explanations we come up with for the phenomena we observe are actually contributing to testable knowledge, or whether their value remains purely anecdotal. Here, we present examples to argue that, under certain conditions, data from long-term observations and observation networks can have equivalent or even higher scientific validity than controlled experiments. Internal validity is particularly enhanced if observations are combined with modeling. Long-term observations of ecosystem-atmosphere fluxes identify trends and temporal scales of variability. Observation networks reveal spatial patterns and variations, and long-term observation networks combine both aspects. A necessary condition for such observations to gain validity beyond the anecdotal is the requirement that the data are comparable: a comparison of two measured values, separated in time or space, must inform us objectively whether (e.g.) one value is larger than the other. In turn, a necessary condition for the comparability of data is the compatibility of the sensors and procedures used to generate them. Compatibility ensures that we compare "apples to apples": that measurements conducted in identical conditions give the same values (within suitable uncertainty intervals). In principle, a useful tool to achieve comparability and compatibility is the standardization of sensors and methods. However, due to the diversity of ecosystems and settings, standardization in ecosystem-atmosphere exchange is difficult. We discuss some of the challenges and pitfalls of standardization across networks.

Ozone reference models for the middle atmosphere (new CIRA)

NASA Technical Reports Server (NTRS)

Keating, G. M.; Pitts, M. C.; Young, D. F.

1989-01-01

Models of ozone vertical structure were generated that were based on multiple data sets from satellites. The very good absolute accuracy of the individual data sets allowed the data to be directly combined to generate these models. The data used for generation of these models are from some of the most recent satellite measurements over the period 1978 to 1983. A discussion is provided of validation and error analyses of these data sets. Also, inconsistencies in data sets brought about by temporal variations or other factors are indicated. The models cover the pressure range from from 20 to 0.003 mb (25 to 90 km). The models for pressures less than 0.5 mb represent only the day side and are only provisional since there was limited longitudinal coverage at these levels. The models start near 25 km in accord with previous COSPAR international reference atmosphere (CIRA) models. Models are also provided of ozone mixing ratio as a function of height. The monthly standard deviation and interannual variations relative to zonal means are also provided. In addition to the models of monthly latitudinal variations in vertical structure based on satellite measurements, monthly models of total column ozone and its characteristic variability as a function of latitude based on four years of Nimbus 7 measurements, models of the relationship between vertical structure and total column ozone, and a midlatitude annual mean model are incorporated in this set of ozone reference atmospheres. Various systematic variations are discussed including the annual, semiannual, and quasibiennial oscillations, and diurnal, longitudinal, and response to solar activity variations.

Complex terrain experiments in the New European Wind Atlas.

PubMed

Mann, J; Angelou, N; Arnqvist, J; Callies, D; Cantero, E; Arroyo, R Chávez; Courtney, M; Cuxart, J; Dellwik, E; Gottschall, J; Ivanell, S; Kühn, P; Lea, G; Matos, J C; Palma, J M L M; Pauscher, L; Peña, A; Rodrigo, J Sanz; Söderberg, S; Vasiljevic, N; Rodrigues, C Veiga

2017-04-13

The New European Wind Atlas project will create a freely accessible wind atlas covering Europe and Turkey, develop the model chain to create the atlas and perform a series of experiments on flow in many different kinds of complex terrain to validate the models. This paper describes the experiments of which some are nearly completed while others are in the planning stage. All experiments focus on the flow properties that are relevant for wind turbines, so the main focus is the mean flow and the turbulence at heights between 40 and 300 m. Also extreme winds, wind shear and veer, and diurnal and seasonal variations of the wind are of interest. Common to all the experiments is the use of Doppler lidar systems to supplement and in some cases replace completely meteorological towers. Many of the lidars will be equipped with scan heads that will allow for arbitrary scan patterns by several synchronized systems. Two pilot experiments, one in Portugal and one in Germany, show the value of using multiple synchronized, scanning lidar, both in terms of the accuracy of the measurements and the atmospheric physical processes that can be studied. The experimental data will be used for validation of atmospheric flow models and will by the end of the project be freely available.This article is part of the themed issue 'Wind energy in complex terrains'. © 2017 The Authors.

Validation of a predictive model coupling gas transfer and microbial growth in fresh food packed under modified atmosphere.

PubMed

Guillard, V; Couvert, O; Stahl, V; Hanin, A; Denis, C; Huchet, V; Chaix, E; Loriot, C; Vincelot, T; Thuault, D

2016-09-01

Predicting microbial safety of fresh products in modified atmosphere packaging implies to take into account the dynamic of O2, CO2 and N2 exchanges in the system and its effect on microbial growth. In this paper a mechanistic model coupling gas transfer and predictive microbiology was validated using dedicated challenge-tests performed on poultry meat, fresh salmon and processed cheese, inoculated with either Listeria monocytogenes or Pseudomonas fluorescens and packed in commercially used packaging materials (tray + lid films). The model succeeded in predicting the relative variation of O2, CO2 and N2 partial pressure in headspace and the growth of the studied microorganisms without any parameter identification. This work highlighted that the respiration of the targeted microorganism itself and/or that of the naturally present microflora could not be neglected in most of the cases, and could, in the particular case of aerobic microbes contribute to limit the growth by removing all residual O2 in the package. This work also confirmed the low sensitivity of L. monocytogenes toward CO2 while that of P. fluorescens permitted to efficiently prevent its growth by choosing the right combination of packaging gas permeability value and initial % of CO2 initially flushed in the pack. Copyright © 2016 Elsevier Ltd. All rights reserved.

Complex terrain experiments in the New European Wind Atlas

PubMed Central

Angelou, N.; Callies, D.; Cantero, E.; Arroyo, R. Chávez; Courtney, M.; Cuxart, J.; Dellwik, E.; Gottschall, J.; Ivanell, S.; Kühn, P.; Lea, G.; Matos, J. C.; Palma, J. M. L. M.; Peña, A.; Rodrigo, J. Sanz; Söderberg, S.; Vasiljevic, N.; Rodrigues, C. Veiga

2017-01-01

The New European Wind Atlas project will create a freely accessible wind atlas covering Europe and Turkey, develop the model chain to create the atlas and perform a series of experiments on flow in many different kinds of complex terrain to validate the models. This paper describes the experiments of which some are nearly completed while others are in the planning stage. All experiments focus on the flow properties that are relevant for wind turbines, so the main focus is the mean flow and the turbulence at heights between 40 and 300 m. Also extreme winds, wind shear and veer, and diurnal and seasonal variations of the wind are of interest. Common to all the experiments is the use of Doppler lidar systems to supplement and in some cases replace completely meteorological towers. Many of the lidars will be equipped with scan heads that will allow for arbitrary scan patterns by several synchronized systems. Two pilot experiments, one in Portugal and one in Germany, show the value of using multiple synchronized, scanning lidar, both in terms of the accuracy of the measurements and the atmospheric physical processes that can be studied. The experimental data will be used for validation of atmospheric flow models and will by the end of the project be freely available. This article is part of the themed issue ‘Wind energy in complex terrains’. PMID:28265025

Development, Production and Validation of the NOAA Solar Irradiance Climate Data Record

NASA Astrophysics Data System (ADS)

Coddington, O.; Lean, J.; Pilewskie, P.; Snow, M. A.; Lindholm, D. M.

2015-12-01

A new climate data record of Total Solar Irradiance (TSI) and Solar Spectral Irradiance (SSI), including source code and supporting documentation is now publicly available as part of the National Oceanographic and Atmospheric Administration's (NOAA) National Centers for Environmental Information (NCEI) Climate Data Record (CDR) Program. Daily and monthly averaged values of TSI and SSI, with associated time and wavelength dependent uncertainties, are estimated from 1882 to the present with yearly averaged values since 1610, updated quarterly for the foreseeable future. The new Solar Irradiance Climate Data Record, jointly developed by the University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes from quiet Sun conditions when bright faculae and dark sunspots are present on the solar disk. The magnitudes of the irradiance changes that these features produce are determined from linear regression of the proxy Mg II index and sunspot area indices against the approximately decade-long solar irradiance measurements made by instruments on the SOlar Radiation and Climate Experiment (SORCE) spacecraft. We describe the model formulation, uncertainty estimates, operational implementation and validation approach. Future efforts to improve the uncertainty estimates of the Solar Irradiance CDR arising from model assumptions, and augmentation of the solar irradiance reconstructions with direct measurements from the Total and Spectral Solar Irradiance Sensor (TSIS: launch date, July 2017) are also discussed.

High resolution regional climate simulation of the Hawaiian Islands - Validation of the historical run from 2003 to 2012

NASA Astrophysics Data System (ADS)

Xue, L.; Newman, A. J.; Ikeda, K.; Rasmussen, R.; Clark, M. P.; Monaghan, A. J.

2016-12-01

A high-resolution (a 1.5 km grid spacing domain nested within a 4.5 km grid spacing domain) 10-year regional climate simulation over the entire Hawaiian archipelago is being conducted at the National Center for Atmospheric Research (NCAR) using the Weather Research and Forecasting (WRF) model version 3.7.1. Numerical sensitivity simulations of the Hawaiian Rainband Project (HaRP, a filed experiment from July to August in 1990) showed that the simulated precipitation properties are sensitive to initial and lateral boundary conditions, sea surface temperature (SST), land surface models, vertical resolution and cloud droplet concentration. The validations of model simulated statistics of the trade wind inversion, temperature, wind field, cloud cover, and precipitation over the islands against various observations from soundings, satellites, weather stations and rain gauges during the period from 2003 to 2012 will be presented at the meeting.

Water Isotopes in Precipitation: Data/Model Comparison for Present-Day and Past Climates

NASA Technical Reports Server (NTRS)

Jouzel, J.; Hoffmann, G.; Masson, V.

1998-01-01

Variations of HDO and H2O-18 concentrations are observed in precipitation both on a geographical and on a temporal basis. These variations, resulting from successive isotopic fractionation processes at each phase change of water during its atmospheric cycle, are well documented through the IAEA/WMO network and other sources. Isotope concentrations are, in middle and high latitudes, linearly related to the annual mean temperature at the precipitation site. Paleoclimatologists have used this relationship to infer paleotemperatures from isotope paleodata extractable from ice cores, deep groundwater and other such sources. For this application to be valid, however, the spatial relationship must also hold in time at a given location as the location undergoes a series of climatic changes. Progress in water isotope modeling aimed at examining and evaluating this assumption has been recently reviewed with a focus on polar regions and, more specifically, on Greenland. This article was largely based on the results obtained using the isotopic version of the NASA/GISS Atmospheric General Circulation Model (AGCM) fitted with isotope tracer diagnostics. We extend this review in comparing the results of two different isotopic AGCMs (NASA/GISS and ECHAM) and in examining, with a more global perspective, the validity of the above assumption, i.e. the equivalence of the spatial and temporal isotope-temperature relationship. We also examine recent progress made in modeling the relationship between the conditions prevailing in moisture source regions for precipitation and the deuterium-excess of that precipitation.

The importance of atmospheric correction for airborne hyperspectral remote sensing of shallow waters: application to depth estimation

NASA Astrophysics Data System (ADS)

Castillo-López, Elena; Dominguez, Jose Antonio; Pereda, Raúl; de Luis, Julio Manuel; Pérez, Ruben; Piña, Felipe

2017-10-01

Accurate determination of water depth is indispensable in multiple aspects of civil engineering (dock construction, dikes, submarines outfalls, trench control, etc.). To determine the type of atmospheric correction most appropriate for the depth estimation, different accuracies are required. Accuracy in bathymetric information is highly dependent on the atmospheric correction made to the imagery. The reduction of effects such as glint and cross-track illumination in homogeneous shallow-water areas improves the results of the depth estimations. The aim of this work is to assess the best atmospheric correction method for the estimation of depth in shallow waters, considering that reflectance values cannot be greater than 1.5 % because otherwise the background would not be seen. This paper addresses the use of hyperspectral imagery to quantitative bathymetric mapping and explores one of the most common problems when attempting to extract depth information in conditions of variable water types and bottom reflectances. The current work assesses the accuracy of some classical bathymetric algorithms (Polcyn-Lyzenga, Philpot, Benny-Dawson, Hamilton, principal component analysis) when four different atmospheric correction methods are applied and water depth is derived. No atmospheric correction is valid for all type of coastal waters, but in heterogeneous shallow water the model of atmospheric correction 6S offers good results.

POLARIZED LINE FORMATION IN NON-MONOTONIC VELOCITY FIELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sampoorna, M.; Nagendra, K. N., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in

2016-12-10

For a correct interpretation of the observed spectro-polarimetric data from astrophysical objects such as the Sun, it is necessary to solve the polarized line transfer problems taking into account a realistic temperature structure, the dynamical state of the atmosphere, a realistic scattering mechanism (namely, the partial frequency redistribution—PRD), and the magnetic fields. In a recent paper, we studied the effects of monotonic vertical velocity fields on linearly polarized line profiles formed in isothermal atmospheres with and without magnetic fields. However, in general the velocity fields that prevail in dynamical atmospheres of astrophysical objects are non-monotonic. Stellar atmospheres with shocks, multi-componentmore » supernova atmospheres, and various kinds of wave motions in solar and stellar atmospheres are examples of non-monotonic velocity fields. Here we present studies on the effect of non-relativistic non-monotonic vertical velocity fields on the linearly polarized line profiles formed in semi-empirical atmospheres. We consider a two-level atom model and PRD scattering mechanism. We solve the polarized transfer equation in the comoving frame (CMF) of the fluid using a polarized accelerated lambda iteration method that has been appropriately modified for the problem at hand. We present numerical tests to validate the CMF method and also discuss the accuracy and numerical instabilities associated with it.« less

Validation of China-wide interpolated daily climate variables from 1960 to 2011

NASA Astrophysics Data System (ADS)

Yuan, Wenping; Xu, Bing; Chen, Zhuoqi; Xia, Jiangzhou; Xu, Wenfang; Chen, Yang; Wu, Xiaoxu; Fu, Yang

2015-02-01

Temporally and spatially continuous meteorological variables are increasingly in demand to support many different types of applications related to climate studies. Using measurements from 600 climate stations, a thin-plate spline method was applied to generate daily gridded climate datasets for mean air temperature, maximum temperature, minimum temperature, relative humidity, sunshine duration, wind speed, atmospheric pressure, and precipitation over China for the period 1961-2011. A comprehensive evaluation of interpolated climate was conducted at 150 independent validation sites. The results showed superior performance for most of the estimated variables. Except for wind speed, determination coefficients ( R 2) varied from 0.65 to 0.90, and interpolations showed high consistency with observations. Most of the estimated climate variables showed relatively consistent accuracy among all seasons according to the root mean square error, R 2, and relative predictive error. The interpolated data correctly predicted the occurrence of daily precipitation at validation sites with an accuracy of 83 %. Moreover, the interpolation data successfully explained the interannual variability trend for the eight meteorological variables at most validation sites. Consistent interannual variability trends were observed at 66-95 % of the sites for the eight meteorological variables. Accuracy in distinguishing extreme weather events differed substantially among the meteorological variables. The interpolated data identified extreme events for the three temperature variables, relative humidity, and sunshine duration with an accuracy ranging from 63 to 77 %. However, for wind speed, air pressure, and precipitation, the interpolation model correctly identified only 41, 48, and 58 % of extreme events, respectively. The validation indicates that the interpolations can be applied with high confidence for the three temperatures variables, as well as relative humidity and sunshine duration based on the performance of these variables in estimating daily variations, interannual variability, and extreme events. Although longitude, latitude, and elevation data are included in the model, additional information, such as topography and cloud cover, should be integrated into the interpolation algorithm to improve performance in estimating wind speed, atmospheric pressure, and precipitation.

TRANSMISSION SPECTRA OF TRANSITING PLANET ATMOSPHERES: MODEL VALIDATION AND SIMULATIONS OF THE HOT NEPTUNE GJ 436b FOR THE JAMES WEBB SPACE TELESCOPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shabram, Megan; Fortney, Jonathan J.; Greene, Thomas P.

We explore the transmission spectrum of the Neptune-class exoplanet GJ 436b, including the possibility that its atmospheric opacity is dominated by a variety of nonequilibrium chemical products. We also validate our transmission code by demonstrating close agreement with analytic models that use only Rayleigh scattering or water vapor opacity. We find broad disagreement with radius variations predicted by another published model. For GJ 436b, the relative coolness of the planet's atmosphere, along with its implied high metallicity, may make it dissimilar in character compared to 'hot Jupiters'. Some recent observational and modeling efforts suggest low relative abundances of H{sub 2}Omore » and CH{sub 4} present in GJ 436b's atmosphere, compared to calculations from equilibrium chemistry. We include these characteristics in our models and examine the effects of absorption from methane-derived higher-order hydrocarbons. To our knowledge, the effects of these nonequilibrium chemical products on the spectra of close-in giant planets have not previously been investigated. Significant absorption from HCN and C{sub 2}H{sub 2} is found throughout the infrared, while C{sub 2}H{sub 4} and C{sub 2}H{sub 6} are less easily seen. We perform detailed simulations of James Webb Space Telescope observations, including all likely noise sources, and find that we will be able to constrain chemical abundance regimes from this planet's transmission spectrum. For instance, the width of the features at 1.5, 3.3, and 7 {mu}m indicates the amount of HCN versus C{sub 2}H{sub 2} present. The NIRSpec prism mode will be useful due to its large spectral range and the relatively large number of photo-electrons recorded per spectral resolution element. However, extremely bright host stars like GJ 436 may be better observed with a higher spectroscopic resolution mode in order to avoid detector saturation. We find that observations with the MIRI low-resolution spectrograph should also have high signal-to-noise in the 5-10 {mu}m range due to the brightness of the star and the relatively low spectral resolution (R {approx} 100) of this mode.« less

DARPA super resolution vision system (SRVS) robust turbulence data collection and analysis

NASA Astrophysics Data System (ADS)

Espinola, Richard L.; Leonard, Kevin R.; Thompson, Roger; Tofsted, David; D'Arcy, Sean

2014-05-01

Atmospheric turbulence degrades the range performance of military imaging systems, specifically those intended for long range, ground-to-ground target identification. The recent Defense Advanced Research Projects Agency (DARPA) Super Resolution Vision System (SRVS) program developed novel post-processing system components to mitigate turbulence effects on visible and infrared sensor systems. As part of the program, the US Army RDECOM CERDEC NVESD and the US Army Research Laboratory Computational & Information Sciences Directorate (CISD) collaborated on a field collection and atmospheric characterization of a two-handed weapon identification dataset through a diurnal cycle for a variety of ranges and sensor systems. The robust dataset is useful in developing new models and simulations of turbulence, as well for providing as a standard baseline for comparison of sensor systems in the presence of turbulence degradation and mitigation. In this paper, we describe the field collection and atmospheric characterization and present the robust dataset to the defense, sensing, and security community. In addition, we present an expanded model validation of turbulence degradation using the field collected video sequences.

Mars Aerocapture and Validation of Mars-GRAM with TES Data

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2005-01-01

Mars Global Reference Atmospheric Model (Mars-GRAM) is a widely-used engineering- level Mars atmospheric model. Applications include systems design, performance analysis, and operations planning for aerobraking, entry descent and landing, and aerocapture. Typical Mars aerocapture periapsis altitudes (for systems with rigid-aeroshell heat shields) are about 50 km. This altitude is above the 0-40 km height range covered by Mars Global Surveyor Thermal Emission Spectrometer (TES) nadir observations. Recently, TES limb sounding data have been made available, spanning more than two Mars years (more than 200,000 data profiles) with altitude coverage up to about 60 km, well within the height range of interest for aerocapture. Results are presented comparing Mars-GRAM atmospheric density with densities from TES nadir and limb sounding observations. A new Mars-GRAM feature is described which allows individual TES nadir or limb profiles to be extracted from the large TES databases, and to be used as an optional replacement for standard Mars-GRAM background (climatology) conditions. For Monte-Carlo applications such as aerocapture guidance and control studies, Mars-GRAM perturbations are available using these TES profile background conditions.

Modeling of polarimetric BRDF characteristics of painted surfaces

NASA Astrophysics Data System (ADS)

Zhang, Ying; Wang, Zeying; Zhao, Huijie

2014-11-01

In this paper a pBRDF (polarimetric Bidirectional Reflectance Distribution Function) model of painted surfaces coupled with atmospheric polarization characteristics is built and the method of simulating polarimetric radiation reaching the imaging system is advanced. Firstly, the composition of the radiation reaching the sensor is analyzed. Then, the pBRDF model of painted surfaces is developed according to the microfacet theory presented by G. Priest and the downwelled skylight polarization is modeled based on the vector radiative transfer model RT3. Furthermore, the modeled polarization state of reflected light from the surfaces was achieved through integrating the directional polarimetric information of the whole hemisphere, adding the modeled polarimetric factors of incident diffused skylight. Finally, the polarimetric radiance reaching the sensor is summed up with the assumption that the target-sensor path is assumed to be negligible since it is relatively short in the current imaging geometry. The modeled results are related to the solar-sensor geometry, atmospheric conditions and the features of the painted surfaces. This result can be used to simulate the imaging under different weather conditions and further work for the validation experiments of the model need to be done.

Improvement of web-based data acquisition and management system for GOSAT validation lidar data analysis

NASA Astrophysics Data System (ADS)

Okumura, Hiroshi; Takubo, Shoichiro; Kawasaki, Takeru; Abdullah, Indra Nugraha; Uchino, Osamu; Morino, Isamu; Yokota, Tatsuya; Nagai, Tomohiro; Sakai, Tetsu; Maki, Takashi; Arai, Kohei

2013-01-01

A web-base data acquisition and management system for GOSAT (Greenhouse gases Observation SATellite) validation lidar data-analysis has been developed. The system consists of data acquisition sub-system (DAS) and data management sub-system (DMS). DAS written in Perl language acquires AMeDAS (Automated Meteorological Data Acquisition System) ground-level local meteorological data, GPS Radiosonde upper-air meteorological data, ground-level oxidant data, skyradiometer data, skyview camera images, meteorological satellite IR image data and GOSAT validation lidar data. DMS written in PHP language demonstrates satellite-pass date and all acquired data. In this article, we briefly describe some improvement for higher performance and higher data usability. GPS Radiosonde upper-air meteorological data and U.S. standard atmospheric model in DAS automatically calculate molecule number density profiles. Predicted ozone density prole images above Saga city are also calculated by using Meteorological Research Institute (MRI) chemistry-climate model version 2 for comparison to actual ozone DIAL data.

Empirical scaling laws for coronal heating

NASA Technical Reports Server (NTRS)

Golub, L.

1983-01-01

The origins and uses of scaling laws in studies of stellar outer atmospheres are reviewed with particular emphasis on the properties of coronal loops. Some evidence is presented for a fundamental structuring of the solar corona and the thermodynamics of scaling laws are discussed. It is found that magnetic field-related scaling laws can be obtained by relating coronal pressure, temperature, and magnetic field strength. Available data validate this method. Some parameters of the theory, however, must be treated as adjustable, and it is considered necessary to examine data from other stars in order to determine the validity of the parameters. Using detailed observational data, the applicability of single loop models is examined.

Validation of a Statistical Methodology for Extracting Vegetation Feedbacks: Focus on North African Ecosystems in the Community Earth System Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Yan; Notaro, Michael; Wang, Fuyao

Generalized equilibrium feedback assessment (GEFA) is a potentially valuable multivariate statistical tool for extracting vegetation feedbacks to the atmosphere in either observations or coupled Earth system models. The reliability of GEFA at capturing the terrestrial impacts on regional climate is demonstrated in this paper using the National Center for Atmospheric Research Community Earth System Model (CESM), with focus on North Africa. The feedback is assessed statistically by applying GEFA to output from a fully coupled control run. To reduce the sampling error caused by short data records, the traditional or full GEFA is refined through stepwise GEFA by dropping unimportantmore » forcings. Two ensembles of dynamical experiments are developed for the Sahel or West African monsoon region against which GEFA-based vegetation feedbacks are evaluated. In these dynamical experiments, regional leaf area index (LAI) is modified either alone or in conjunction with soil moisture, with the latter runs motivated by strong regional soil moisture–LAI coupling. Stepwise GEFA boasts higher consistency between statistically and dynamically assessed atmospheric responses to land surface anomalies than full GEFA, especially with short data records. GEFA-based atmospheric responses are more consistent with the coupled soil moisture–LAI experiments, indicating that GEFA is assessing the combined impacts of coupled vegetation and soil moisture. Finally, both the statistical and dynamical assessments reveal a negative vegetation–rainfall feedback in the Sahel associated with an atmospheric stability mechanism in CESM versus a weaker positive feedback in the West African monsoon region associated with a moisture recycling mechanism in CESM.« less

Validation of a Statistical Methodology for Extracting Vegetation Feedbacks: Focus on North African Ecosystems in the Community Earth System Model

DOE PAGES

Yu, Yan; Notaro, Michael; Wang, Fuyao; ...

2018-02-05

Generalized equilibrium feedback assessment (GEFA) is a potentially valuable multivariate statistical tool for extracting vegetation feedbacks to the atmosphere in either observations or coupled Earth system models. The reliability of GEFA at capturing the terrestrial impacts on regional climate is demonstrated in this paper using the National Center for Atmospheric Research Community Earth System Model (CESM), with focus on North Africa. The feedback is assessed statistically by applying GEFA to output from a fully coupled control run. To reduce the sampling error caused by short data records, the traditional or full GEFA is refined through stepwise GEFA by dropping unimportantmore » forcings. Two ensembles of dynamical experiments are developed for the Sahel or West African monsoon region against which GEFA-based vegetation feedbacks are evaluated. In these dynamical experiments, regional leaf area index (LAI) is modified either alone or in conjunction with soil moisture, with the latter runs motivated by strong regional soil moisture–LAI coupling. Stepwise GEFA boasts higher consistency between statistically and dynamically assessed atmospheric responses to land surface anomalies than full GEFA, especially with short data records. GEFA-based atmospheric responses are more consistent with the coupled soil moisture–LAI experiments, indicating that GEFA is assessing the combined impacts of coupled vegetation and soil moisture. Finally, both the statistical and dynamical assessments reveal a negative vegetation–rainfall feedback in the Sahel associated with an atmospheric stability mechanism in CESM versus a weaker positive feedback in the West African monsoon region associated with a moisture recycling mechanism in CESM.« less

The Role of the Indian Ocean Sector for Prediction of the Coupled Indo-Pacific System: Impact of Atmospheric Coupling

NASA Technical Reports Server (NTRS)

Hackert, E. C.; Busalacchi, A. J.; Carton, J.; Murtugudde, R.; Arkin, P.; Evans, M. N.

2017-01-01

Indian Ocean (IO) dynamics impact ENSO predictability by influencing wind and precipitation anomalies in the Pacific. To test if the upstream influence of the IO improves ENSO validation statistics, a combination of forced ocean, atmosphere, and coupled models are utilized. In one experiment, the full tropical Indo-Pacific region atmosphere is forced by observed interannual SST anomalies. In the other, the IO is forced by climatological SST. Differences between these two forced atmospheric model experiments spotlight a much richer wind response pattern in the Pacific than previous studies that used idealized forcing and simple linear atmospheric models. Weak westerlies are found near the equator similar to earlier literature. However, at initialization strong easterlies between 30 deg. S to 10 deg. S and 0 deg. N to 25 deg. N and equatorial convergence of the meridional winds across the entire Pacific are unique findings from this paper. The large-scale equatorial divergence west of the dateline and northeasterly-to-northwesterly cross-equatorial flow converging on the equator east of the dateline in the Pacific are generated from interannual IO SST coupling. In addition, off-equatorial downwelling curl impacts large-scale oceanic waves (i.e., Rossby waves reflect as western boundary Kelvin waves). After 3 months, these downwelling equatorial Kelvin waves propagate across the Pacific and strengthen the NINO3 SST. Eventually Bjerknes feedbacks take hold in the eastern Pacific which allows this warm anomaly to grow. Coupled forecasts for NINO3 SST anomalies for 1993-2014 demonstrate that including interannual IO forcing significantly improves predictions for 3-9 month lead times.

The role of the Indian Ocean sector for prediction of the coupled Indo-Pacific system: Impact of atmospheric coupling

NASA Astrophysics Data System (ADS)

Hackert, E. C.; Busalacchi, A. J.; Carton, J.; Murtugudde, R.; Arkin, P.; Evans, M. N.

2017-04-01

Indian Ocean (IO) dynamics impact ENSO predictability by influencing wind and precipitation anomalies in the Pacific. To test if the upstream influence of the IO improves ENSO validation statistics, a combination of forced ocean, atmosphere, and coupled models are utilized. In one experiment, the full tropical Indo-Pacific region atmosphere is forced by observed interannual SST anomalies. In the other, the IO is forced by climatological SST. Differences between these two forced atmospheric model experiments spotlight a much richer wind response pattern in the Pacific than previous studies that used idealized forcing and simple linear atmospheric models. Weak westerlies are found near the equator similar to earlier literature. However, at initialization strong easterlies between 30°S-10°S and 0°N-25°N and equatorial convergence of the meridional winds across the entire Pacific are unique findings from this paper. The large-scale equatorial divergence west of the dateline and northeasterly-to-northwesterly cross-equatorial flow converging on the equator east of the dateline in the Pacific are generated from interannual IO SST coupling. In addition, off-equatorial downwelling curl impacts large-scale oceanic waves (i.e., Rossby waves reflect as western boundary Kelvin waves). After 3 months, these downwelling equatorial Kelvin waves propagate across the Pacific and strengthen the NINO3 SST. Eventually Bjerknes feedbacks take hold in the eastern Pacific which allows this warm anomaly to grow. Coupled forecasts for NINO3 SST anomalies for 1993-2014 demonstrate that including interannual IO forcing significantly improves predictions for 3-9 month lead times.

Forecasting surface-layer atmospheric parameters at the Large Binocular Telescope site

NASA Astrophysics Data System (ADS)

Turchi, Alessio; Masciadri, Elena; Fini, Luca

2017-04-01

In this paper, we quantify the performance of an automated weather forecast system implemented on the Large Binocular Telescope (LBT) site at Mt Graham (Arizona) in forecasting the main atmospheric parameters close to the ground. The system employs a mesoscale non-hydrostatic numerical model (Meso-Nh). To validate the model, we compare the forecasts of wind speed, wind direction, temperature and relative humidity close to the ground with the respective values measured by instrumentation installed on the telescope dome. The study is performed over a large sample of nights uniformly distributed over 2 yr. The quantitative analysis is done using classical statistical operators [bias, root-mean-square error (RMSE) and σ] and contingency tables, which allows us to extract complementary key information, such as the percentage of correct detections (PC) and the probability of obtaining a correct detection within a defined interval of values (POD). The results of our study indicate that the model performance in forecasting the atmospheric parameters we have just cited are very good, in some cases excellent: RMSE for temperature is below 1°C, for relative humidity it is 14 per cent and for the wind speed it is around 2.5 m s-1. The relative error of the RMSE for wind direction varies from 9 to 17 per cent depending on the wind speed conditions. This work is performed in the context of the ALTA (Advanced LBT Turbulence and Atmosphere) Center project, whose final goal is to provide forecasts of all the atmospheric parameters and the optical turbulence to support LBT observations, adaptive optics facilities and interferometric facilities.

Predicting Aspergillus fumigatus exposure from composting facilities using a dispersion model: A conditional calibration and validation.

PubMed

Douglas, Philippa; Tyrrel, Sean F; Kinnersley, Robert P; Whelan, Michael; Longhurst, Philip J; Hansell, Anna L; Walsh, Kerry; Pollard, Simon J T; Drew, Gillian H

2017-01-01

Bioaerosols are released in elevated quantities from composting facilities and are associated with negative health effects, although dose-response relationships are unclear. Exposure levels are difficult to quantify as established sampling methods are costly, time-consuming and current data provide limited temporal and spatial information. Confidence in dispersion model outputs in this context would be advantageous to provide a more detailed exposure assessment. We present the calibration and validation of a recognised atmospheric dispersion model (ADMS) for bioaerosol exposure assessments. The model was calibrated by a trial and error optimisation of observed Aspergillus fumigatus concentrations at different locations around a composting site. Validation was performed using a second dataset of measured concentrations for a different site. The best fit between modelled and measured data was achieved when emissions were represented as a single area source, with a temperature of 29°C. Predicted bioaerosol concentrations were within an order of magnitude of measured values (1000-10,000CFU/m 3 ) at the validation site, once minor adjustments were made to reflect local differences between the sites (r 2 >0.7 at 150, 300, 500 and 600m downwind of source). Results suggest that calibrated dispersion modelling can be applied to make reasonable predictions of bioaerosol exposures at multiple sites and may be used to inform site regulation and operational management. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

Feeling bogged down about climate change mitigation? Insights from a new high resolution peatland-bog model validated at two Dutch monitoring sites.

NASA Astrophysics Data System (ADS)

Lippmann, Tanya; van Huissteden, Ko; Hendriks, Dimmie

2017-04-01

Increasing the global carbon sink is one of two options to mitigate CO2 and CH4 increases in the atmosphere (the other is emissions reductions at the source). Peatlands release carbon to the atmosphere when disturbed by natural or human causes and absorb carbon when vegetation and soil organic matter accumulate after rewetting or natural revegetation. However, rewetting of drained peatlands is frequently not considered as a climate mitigation strategy due to the enhanced methane emissions that accompany newly formed anaerobic peatland environments. We hypothesise that at most sites, this trend will be temporal but long-term, lasting for tens of years post re-wetting before stabilisation takes place. This study investigates the ability of rewetted peatland sites to act as either a source or sink for atmospheric methane and carbon dioxide under climate change. The hydrology of a peatland is fundamental to its functioning. Therefore, the use of a full water balance table has the potential to simulate greenhouse gas fluxes to a greater degree of certainty. MODFLOW is the internationally most widely used ground and surface water model and is freely available to the scientific community. This is the first time that a gridded peatland process based model has been constructed at a spatial resolution as high as 25m x 25m. This new high-resolution model allows for investigation into the complex biophysical and hydrological factors that are necessary to reliably estimate atmospheric greenhouse gas fluxes in a peatland ecosystem. We assess the model's skill against observations collected at two monitoring sites of differing soil properties and vegetation in the Netherlands. These results discuss site-specific suitability of peatland regeneration, useful for climate change mitigation activities. Aside from the insight into transient atmosphere-peatland carbon fluxes, this work is a stepping stone towards more robust model coupling and greater spatial coverage.

A Model for Straight and Helical Solar Jets: II. Parametric Study of the Plasma Beta

NASA Technical Reports Server (NTRS)

Pariat, E.; Dalmasse, K.; DeVore, C. R.; Antiochos, S. K.; Karpen, J. T.

2016-01-01

Context. Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere. Aims. Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e.g. in the vicinity of active regions as well as in coronal holes, and at various scales, from small photospheric spicules to large coronal jets. In all these events, signatures of helical structure and/or twisting/rotating motions are regularly observed. The present study aims to establish that a single model can generally reproduce the observed properties of these jet-like events. Methods. In this study, using our state-of-the-art numerical solver ARMS, we present a parametric study of a numerical tridimensional magnetohydrodynamic (MHD) model of solar jet-like events. Within the MHD paradigm, we study the impact of varying the atmospheric plasma beta on the generation and properties of solar-like jets. Results. The parametric study validates our model of jets for plasma beta ranging from 10(sup 3) to 1, typical of the different layers and magnetic environments of the solar atmosphere. Our model of jets can robustly explain the generation of helical solar jet-like events at various beta less than or equal to 1. We show that the plasma beta modifies the morphology of the helical jet, explaining the different observed shapes of jets at different scales and in different layers of the solar atmosphere. Conclusions. Our results allow us to understand the energisation, triggering, and driving processes of jet-like events. Our model allows us to make predictions of the impulsiveness and energetics of jets as determined by the surrounding environment, as well as the morphological properties of the resulting jets.

Using observations to evaluate biosphere-atmosphere interactions in models

NASA Astrophysics Data System (ADS)

Green, Julia; Konings, Alexandra G.; Alemohammad, Seyed H.; Gentine, Pierre

2017-04-01

Biosphere-atmosphere interactions influence the hydrologic cycle by altering climate and weather patterns (Charney, 1975; Koster et al., 2006; Seneviratne et al., 2006), contributing up to 30% of precipitation and radiation variability in certain regions (Green et al., 2017). They have been shown to contribute to the persistence of drought in Europe (Seneviratne et al., 2006), as well as to increase rainfall in the Amazon (Spracklen et al., 2012). Thus, a true representation of these feedbacks in Earth System Models (ESMs) is crucial for accurate forecasting and planning. However, it has been difficult to validate the performance of ESMs since often-times surface and atmospheric flux data are scarce and/or difficult to observe. In this study, we use the results of a new global observational study (using remotely sensed solar-induced fluorescence to represent the biosphere flux) (Green et al., 2017) to determine how well a suite of 13 ESMs capture biosphere-atmosphere feedbacks. We perform a Conditional Multivariate Granger Causality analysis in the frequency domain with radiation, precipitation and temperature as atmospheric inputs and GPP as the biospheric input. Performing the analysis in the frequency domain allows for separation of feedbacks at different time-scales (subseasonal, seasonal or interannual). Our findings can be used to determine whether there is agreement between models, as well as, to pinpoint regions or time-scales of model bias or inaccuracy, which will provide insight on potential improvement. We demonstrate that in addition to the well-known problem of convective parameterization over land in models, the main issue in representing feedbacks between the land and the atmosphere is due to the misrepresentation of water stress. These results provide a direct quantitative assessment of feedbacks in models and how to improve them. References: Charney, J.G. Dynamics of deserts and drought in the Sahel. Quarterly Journal of the Royal Meteorological Society 101, 193-202 (1975). Green, J.K., Konings, A.G., Alemohammad, S.H., Berry, J., Entekhabi, D., Kolassa, J., Lee, J.E., Gentine, P. Hotspots of terrestrial biosphere-atmosphere feedbacks. In review. (2017). Koster, R. D. et al. GLACE: The Global Land - Atmosphere Coupling Experiment. Part I: Overview. J. Hydrometeorol. 7, 611-625 (2006). Seneviratne, S.I., Lüthi, D., Litschi M., Schär, C. Land-atmosphere coupling and climate change in Europe. Nature 443, 205-209 (2006). Spracklen, D.V, Arnold, S.R., Taylor, C.M. Observations of increased tropical rainfall preceded by air passage over forests. Nature 489, 282-285 (2012).

A first European scale multimedia fate modelling of BDE-209 from 1970 to 2020.

PubMed

Earnshaw, Mark R; Jones, Kevin C; Sweetman, Andy J

2015-01-01

The European Variant Berkeley Trent (EVn-BETR) multimedia fugacity model is used to test the validity of previously derived emission estimates and predict environmental concentrations of the main decabromodiphenyl ether congener, BDE-209. The results are presented here and compared with measured environmental data from the literature. Future multimedia concentration trends are predicted using three emission scenarios (Low, Realistic and High) in the dynamic unsteady state mode covering the period 1970-2020. The spatial and temporal distributions of emissions are evaluated. It is predicted that BDE-209 atmospheric concentrations peaked in 2004 and will decline to negligible levels by 2025. Freshwater concentrations should have peaked in 2011, one year after the emissions peak with sediment concentrations peaking in 2013. Predicted atmospheric concentrations are in good agreement with measured data for the Realistic (best estimate of emissions) and High (worst case scenario) emission scenarios. The Low emission scenario consistently underestimates measured data. The German unilateral ban on the use of DecaBDE in the textile industry is simulated in an additional scenario, the effects of which are mainly observed within Germany with only a small effect on the surrounding areas. Overall, the EVn-BTER model predicts atmospheric concentrations reasonably well, within a factor of 5 and 1.2 for the Realistic and High emission scenarios respectively, providing partial validation for the original emission estimate. Total mean MEC:PEC shows the High emission scenario predicts the best fit between air, freshwater and sediment data. An alternative spatial distribution of emissions is tested, based on higher consumption in EBFRIP member states, resulting in improved agreement between MECs and PECs in comparison with the Uniform spatial distribution based on population density. Despite good agreement between modelled and measured point data, more long-term monitoring datasets are needed to compare predicted trends in concentration to determine the rate of change of POPs within the environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Current to the ionosphere following a lightning stroke

NASA Technical Reports Server (NTRS)

Hale, L. C.; Baginski, M. E.

1987-01-01

A simple analytical expression for calculating the total current waveform to the ionosphere after a lightning stroke is derived. The validity of this expression is demonstrated by comparison with a more rigorous computer solution of Maxwell's equations. The analytic model demonstrates that the temporal variation of the current induced in the ionosphere and global circuit and the corresponding return current in the earth depends on the conductivity profile at intervening altitudes in the middle atmosphere. A conclusion is that capacitative coupling may provide tighter coupling between the lower atmosphere and the ionosphere than usually considered, in both directions, which may help to explain observations which seem to indicate that magnetospheric phenomena may in some instances trigger lightning.

How clear-sky polarization varies with wavelength in the visible-NIR

NASA Astrophysics Data System (ADS)

Pust, Nathan J.; Shaw, Joseph A.

2013-10-01

Because of the increasing variety of applications for polarization imaging and sensing, there is a growing need for information about polarization phenomenology in the natural environment, including the spectral distribution of polarization in the atmosphere. A computer model that has been validated in comparisons with measurements from our all-sky polarization imager has been used here to simulate the spectrum of clear-sky polarization at a many locations around the world, with a wide variety of underlying surface-reflectance and aerosol conditions. This study of the skylight polarization spectral variability shows that there is no simple spectrum that can be assumed or predicted without knowledge of the atmospheric aerosol properties and underlying surface reflectance.

The importance and attainment of accurate absolute radiometric calibration

NASA Technical Reports Server (NTRS)

Slater, P. N.

1984-01-01

The importance of accurate absolute radiometric calibration is discussed by reference to the needs of those wishing to validate or use models describing the interaction of electromagnetic radiation with the atmosphere and earth surface features. The in-flight calibration methods used for the Landsat Thematic Mapper (TM) and the Systeme Probatoire d'Observation de la Terre, Haute Resolution visible (SPOT/HRV) systems are described and their limitations discussed. The questionable stability of in-flight absolute calibration methods suggests the use of a radiative transfer program to predict the apparent radiance, at the entrance pupil of the sensor, of a ground site of measured reflectance imaged through a well characterized atmosphere. The uncertainties of such a method are discussed.

World Ocean Circulation Experiment

NASA Technical Reports Server (NTRS)

Clarke, R. Allyn

1992-01-01

The oceans are an equal partner with the atmosphere in the global climate system. The World Ocean Circulation Experiment is presently being implemented to improve ocean models that are useful for climate prediction both by encouraging more model development but more importantly by providing quality data sets that can be used to force or to validate such models. WOCE is the first oceanographic experiment that plans to generate and to use multiparameter global ocean data sets. In order for WOCE to succeed, oceanographers must establish and learn to use more effective methods of assembling, quality controlling, manipulating and distributing oceanographic data.

Simulation of Atmospheric-Entry Capsules in the Subsonic Regime

NASA Technical Reports Server (NTRS)

Murman, Scott M.; Childs, Robert E.; Garcia, Joseph A.

2015-01-01

The accuracy of Computational Fluid Dynamics predictions of subsonic capsule aerodynamics is examined by comparison against recent NASA wind-tunnel data at high-Reynolds-number flight conditions. Several aspects of numerical and physical modeling are considered, including inviscid numerical scheme, mesh adaptation, rough-wall modeling, rotation and curvature corrections for eddy-viscosity models, and Detached-Eddy Simulations of the unsteady wake. All of these are considered in isolation against relevant data where possible. The results indicate that an improved predictive capability is developed by considering physics-based approaches and validating the results against flight-relevant experimental data.

Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol-cloud interactions

NASA Astrophysics Data System (ADS)

Calmer, Radiance; Roberts, Gregory C.; Preissler, Jana; Sanchez, Kevin J.; Derrien, Solène; O'Dowd, Colin

2018-05-01

The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts) in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA). In atmospheric research, lightweight RPAs ( < 2.5 kg) are now able to accurately measure atmospheric wind vectors, even in a cloud, which provides essential observing tools for understanding aerosol-cloud interactions. The European project BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) focuses on these specific interactions. In particular, vertical wind velocity at cloud base is a key parameter for studying aerosol-cloud interactions. To measure the three components of wind, a RPA is equipped with a five-hole probe, pressure sensors, and an inertial navigation system (INS). The five-hole probe is calibrated on a multi-axis platform, and the probe-INS system is validated in a wind tunnel. Once mounted on a RPA, power spectral density (PSD) functions and turbulent kinetic energy (TKE) derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland), a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological conditions.

The Global Carbon Cycle: It's a Small World

NASA Astrophysics Data System (ADS)

Ineson, Philip; Milcu, Alexander; Subke, Jens-Arne; Wildman, Dennis; Anderson, Robert; Manning, Peter; Heinemeyer, Andreas

2010-05-01

Predicting future atmospheric concentrations of carbon dioxide (CO2), together with the impacts of these changes on global climate, are some of the most urgent and important challenges facing mankind. Modelling is the only way in which such predictions can be made, leading to the current generation of increasingly complex computer simulations, with associated concerns about embedded assumptions and conflicting model outputs. Alongside analysis of past climates, the GCMs currently represent our only hope of establishing the importance of potential runaway positive feedbacks linking climate change and atmospheric greenhouse gases yet the incorporation of necessary biospheric responses into GCMs markedly increases the uncertainty of predictions. Analysis of the importance of the major components of the global carbon (C) cycle reveals that an understanding of the conditions under which the terrestrial biosphere could switch from an overall carbon (C) sink to a source is critical to our ability to make future climate predictions. Here we present an alternative approach to assessing the short term biotic (plant and soil) sensitivities to elevated temperature and atmospheric CO2 through the use of a purely physical analogue. Centred on the concept of materially-closed systems containing scaled-down ratios of the global C stocks for the atmosphere, vegetation and soil we show that, in these model systems, the terrestrial biosphere is able to buffer a rise of 3oC even when coupled to very strong CO2-temperature positive feedbacks. The system respiratory response appears to be extremely well linked to temperature and is critical in deciding atmospheric concentrations of CO2. Simulated anthropogenic emissions of CO2 into the model systems showed an initial corresponding increase in atmospheric CO2 but, somewhat surprisingly, CO2 concentrations levelled off at ca. 480 p.p.m.v., despite continuing additions of CO2. Experiments were performed in which reversion of atmospheric temperatures, or cessation of CO2 additions, showed rapid and proportionate decreases in atmospheric CO2 concentrations. The results indicate that short term terrestrial feedbacks are not sufficient to induce a CO2-temperature runaway scenario and suggest that predictions of atmospheric CO2 by current GCMs may under-estimate the CO2 fertilisation effect on plants and, hence, over-estimate future atmospheric CO2 increases. Perhaps, more importantly, the experiments show that the impacts of imposed elevated CO2 and temperature increase can be reversed. Whilst clearly representing a simplified version of terrestrial CO2 dynamics, it is proposed that closed system research represents a new form of test-bed for validation of processes represented within digital global CO2 models.

Thermospheric density and satellite drag modeling

NASA Astrophysics Data System (ADS)

Mehta, Piyush Mukesh

The United States depends heavily on its space infrastructure for a vast number of commercial and military applications. Space Situational Awareness (SSA) and Threat Assessment require maintaining accurate knowledge of the orbits of resident space objects (RSOs) and the associated uncertainties. Atmospheric drag is the largest source of uncertainty for low-perigee RSOs. The uncertainty stems from inaccurate modeling of neutral atmospheric mass density and inaccurate modeling of the interaction between the atmosphere and the RSO. In order to reduce the uncertainty in drag modeling, both atmospheric density and drag coefficient (CD) models need to be improved. Early atmospheric density models were developed from orbital drag data or observations of a few early compact satellites. To simplify calculations, densities derived from orbit data used a fixed CD value of 2.2 measured in a laboratory using clean surfaces. Measurements from pressure gauges obtained in the early 1990s have confirmed the adsorption of atomic oxygen on satellite surfaces. The varying levels of adsorbed oxygen along with the constantly changing atmospheric conditions cause large variations in CD with altitude and along the orbit of the satellite. Therefore, the use of a fixed CD in early development has resulted in large biases in atmospheric density models. A technique for generating corrections to empirical density models using precision orbit ephemerides (POE) as measurements in an optimal orbit determination process was recently developed. The process generates simultaneous corrections to the atmospheric density and ballistic coefficient (BC) by modeling the corrections as statistical exponentially decaying Gauss-Markov processes. The technique has been successfully implemented in generating density corrections using the CHAMP and GRACE satellites. This work examines the effectiveness, specifically the transfer of density models errors into BC estimates, of the technique using the CHAMP and GRACE satellites. Moving toward accurate atmospheric models and absolute densities requires physics based models for CD. Closed-form solutions of CD have been developed and exist for a handful of simple geometries (flat plate, sphere, and cylinder). However, for complex geometries, the Direct Simulation Monte Carlo (DSMC) method is an important tool for developing CD models. DSMC is computationally intensive and real-time simulations for CD are not feasible. Therefore, parameterized models for CD are required. Modeling CD for an RSO requires knowledge of the gas-surface interaction (GSI) that defines the manner in which the atmospheric particles exchange momentum and energy with the surface. The momentum and energy exchange is further influenced by likely adsorption of atomic oxygen that may partially or completely cover the surface. An important parameter that characterizes the GSI is the energy accommodation coefficient, α. An innovative and state-of-the-art technique of developing parameterized drag coefficient models is presented and validated using the GRACE satellite. The effect of gas-surface interactions on physical drag coefficients is examined. An attempt to reveal the nature of gas-surface interactions at altitudes above 500 km is made using the STELLA satellite. A model that can accurately estimate CD has the potential to: (i) reduce the sources of uncertainty in the drag model, (ii) improve density estimates by resolving time-varying biases and moving toward absolute densities, and (iii) increase data sources for density estimation by allowing for the use of a wide range of RSOs as information sources. Results from this work have the potential to significantly improve the accuracy of conjunction analysis and SSA.

Oceanic response to tropical cyclone `Phailin' in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Pant, V.; Prakash, K. R.

2016-02-01

Vertical mixing largely explains surface cooling induced by Tropical Cyclones (TCs). However, TC-induced upwelling of deeper waters plays an important role as it partly balances the warming of subsurface waters induced by vertical mixing. Below 100 m, vertical advection results in cooling that persists for a few days after the storm. The present study investigates the integrated ocean response to tropical cyclone `Phaillin' (10-14 October 2013) in the Bay of Bengal (BoB) through both coupled and stand-alone ocean-atmosphere models. Two numerical experiments with different coupling configurations between Regional Ocean Modelling System (ROMS) and Weather Research and Forecasting (WRF) were performed to investigate the impact of Phailin cyclone on the surface and sub-surface oceanic parameters. In the first experiment, ocean circulation model ROMS observe surface wind forcing from a mesoscale atmospheric model (WRF with nested damin setup), while rest forcing parameters are supplied to ROMS from NCEP data. In the second experiment, all surface forcing data to ROMS directly comes from WRF. The modeling components and data fields exchanged between atmospheric and oceanic models are described. The coupled modeling system is used to identify model sensitivity by exchanging prognostic variable fields between the two model components during simulation of Phallin cyclone (10-14 October 2013) in the BoB.In general, the simulated Phailin cyclone track and intensities agree well with observations in WRF simulations. Further, the inter-comparison between stand-alone and coupled model simulations validated against observations highlights better performance of coupled modeling system in simulating the oceanic conditions during the Phailin cyclone event.

Independent Verification of Mars-GRAM 2010 with Mars Climate Sounder Data

NASA Technical Reports Server (NTRS)

Justh, Hilary L.; Burns, Kerry L.

2014-01-01

The Mars Global Reference Atmospheric Model (Mars-GRAM) is an engineering-level atmospheric model widely used for diverse mission and engineering applications. Applications of Mars-GRAM include systems design, performance analysis, and operations planning for aerobraking, entry, descent and landing, and aerocapture. Atmospheric influences on landing site selection and long-term mission conceptualization and development can also be addressed utilizing Mars-GRAM. Mars-GRAM's perturbation modeling capability is commonly used, in a Monte Carlo mode, to perform high-fidelity engineering end-to-end simulations for entry, descent, and landing. Mars-GRAM is an evolving software package resulting in improved accuracy and additional features. Mars-GRAM 2005 has been validated against Radio Science data, and both nadir and limb data from the Thermal Emission Spectrometer (TES). From the surface to 80 km altitude, Mars-GRAM is based on the NASA Ames Mars General Circulation Model (MGCM). Above 80 km, Mars-GRAM is based on the University of Michigan Mars Thermospheric General Circulation Model (MTGCM). The most recent release of Mars-GRAM 2010 includes an update to Fortran 90/95 and the addition of adjustment factors. These adjustment factors are applied to the input data from the MGCM and the MTGCM for the mapping year 0 user-controlled dust case. The adjustment factors are expressed as a function of height (z), latitude and areocentric solar longitude (Ls).

THE SIMULATION OF FINE SCALE NOCTURNAL BOUNDARY LAYER MOTIONS WITH A MESO-SCALE ATMOSPHERIC MODEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Werth, D.; Kurzeja, R.; Parker, M.

A field project over the Atmospheric Radiation Measurement-Clouds and Radiation Testbed (ARM-CART) site during a period of several nights in September, 2007 was conducted to explore the evolution of the low-level jet (LLJ). Data was collected from a tower and a sodar and analyzed for turbulent behavior. To study the full range of nocturnal boundary layer (NBL) behavior, the Regional Atmospheric Modeling System (RAMS) was used to simulate the ARM-CART NBL field experiment and validated against the data collected from the site. This model was run at high resolution, and is ideal for calculating the interactions among the various motionsmore » within the boundary layer and their influence on the surface. The model reproduces adequately the synoptic situation and the formation and dissolution cycles of the low-level jet, although it suffers from insufficient cloud production and excessive nocturnal cooling. The authors suggest that observed heat flux data may further improve the realism of the simulations both in the cloud formation and in the jet characteristics. In a higher resolution simulation, the NBL experiences motion on a range of timescales as revealed by a wavelet analysis, and these are affected by the presence of the LLJ. The model can therefore be used to provide information on activity throughout the depth of the NBL.« less

Validation of the Martilli's Urban Boundary Layer Scheme with measurements from two mid-latitude European cities

NASA Astrophysics Data System (ADS)

Hamdi, R.; Schayes, G.

2005-07-01

The Martilli's urban parameterization scheme is improved and implemented in a mesoscale model in order to take into account the typical effects of a real city on the air temperature near the ground and on the surface exchange fluxes. The mesoscale model is run on a single column using atmospheric data and radiation recorded above roof level as forcing. Here, the authors validate the Martilli's urban boundary layer scheme using measurements from two mid-latitude European cities: Basel, Switzerland and Marseilles, France. For Basel, the model performance is evaluated with observations of canyon temperature, surface radiation, and energy balance fluxes obtained during the Basel urban boundary layer experiment (BUBBLE). The results show that the urban parameterization scheme is able to reproduce the generation of the Urban Heat Island (UHI) effect over urban area and represents correctly most of the behavior of the fluxes typical of the city center of Basel, including the large heat uptake by the urban fabric and the positive sensible heat flux at night. For Marseilles, the model performance is evaluated with observations of surface temperature, canyon temperature, surface radiation, and energy balance fluxes collected during the field experiments to constrain models of atmospheric pollution and transport of emissions (ESCOMPTE) and its urban boundary layer (UBL) campaign. At both urban sites, vegetation cover is less than 20%, therefore, particular attention was directed to the ability of the Martilli's urban boundary layer scheme to reproduce the observations for the Marseilles city center, where the urban parameters and the synoptic forcing are totally different from Basel. Evaluation of the model with wall, road, and roof surface temperatures gave good results. The model correctly simulates the net radiation, canyon temperature, and the partitioning between the turbulent and storage heat fluxes.

Validation of Martilli's urban boundary layer scheme with measurements from two mid-latitude European cities

NASA Astrophysics Data System (ADS)

Hamdi, R.; Schayes, G.

2007-08-01

Martilli's urban parameterization scheme is improved and implemented in a mesoscale model in order to take into account the typical effects of a real city on the air temperature near the ground and on the surface exchange fluxes. The mesoscale model is run on a single column using atmospheric data and radiation recorded above roof level as forcing. Here, the authors validate Martilli's urban boundary layer scheme using measurements from two mid-latitude European cities: Basel, Switzerland and Marseilles, France. For Basel, the model performance is evaluated with observations of canyon temperature, surface radiation, and energy balance fluxes obtained during the Basel urban boundary layer experiment (BUBBLE). The results show that the urban parameterization scheme represents correctly most of the behavior of the fluxes typical of the city center of Basel, including the large heat uptake by the urban fabric and the positive sensible heat flux at night. For Marseilles, the model performance is evaluated with observations of surface temperature, canyon temperature, surface radiation, and energy balance fluxes collected during the field experiments to constrain models of atmospheric pollution and transport of emissions (ESCOMPTE) and its urban boundary layer (UBL) campaign. At both urban sites, vegetation cover is less than 20%, therefore, particular attention was directed to the ability of Martilli's urban boundary layer scheme to reproduce the observations for the Marseilles city center, where the urban parameters and the synoptic forcing are totally different from Basel. Evaluation of the model with wall, road, and roof surface temperatures gave good results. The model correctly simulates the net radiation, canyon temperature, and the partitioning between the turbulent and storage heat fluxes.

An Aerobraking Strategy for Determining Mars Upper Atmospheric Structure

NASA Astrophysics Data System (ADS)

Bougher, S. W.; Murphy, J. R.; Haberle, R. M.

1997-07-01

The Mars Global Surveyor (MGS) spacecraft will enter Mars orbit on Sept. 12, 1997, and thereafter undergo aerobraking for roughly 4-months. The final data-taking orbit to be achieved is sun-synchronous (2PM/2AM). An aerobraking strategy has been developed that not only will provide the walk-in capability needed to safely achieve the required Mars orbit, but also will provide a careful monitoring of the atmospheric structure. In particular, the linkage between the lower (0-100 km) and upper (100- 150 km) Mars atmospheres will be investigated. A suite of complementary measurements is planned that will probe the atmosphere over 0-150 km, including : (1) MGS Accelerometer density and inferred temperatures (100-150 km), (2) MGS Thermal Emission Spectrometer (TES) nadir (25-30 km) and limb (up to about 55 km) temperatures, (3) MGS Electron Reflectometer (ER) F1-peak heights (near 130 km), (4) ground-based microwave disk-averaged temperatures (0-70 km), and (5) Mars Pathfinder (MPF) surface meteorological data at 20 N latitude. These datasets acquired during the aerobraking phase will enable the current state of the atmosphere to be examined. Potential dust storm activity and its manifestations throughout the atmosphere can be monitored over Ls = 184 to 250. A corresponding library of coupled 3-D model simulations, based upon the NASA Ames Mars GCM and the NCAR Mars Thermospheric GCM (MTGCM), will be used to : (1) validate the current state of the Mars atmosphere, (2) investigate the various orbital, seasonal, LAT-LT-LON, and potential dust storm trends, and (3) predict the structure of the Mars atmosphere in the aerobraking corridor that is approaching in future MGS orbits. The in-situ accelerometer and ER data will eventually be used to construct a Mars empirical model covering 100-150 km. We will present a few selected GCM simulations to illustrate the expected atmospheric response to a dust storm event. In addition, we will discuss why these upper atmosphere datasets are important to future Mars missions.

Spectra of polarized thermal radiation in a cloudy atmosphere: Line-by-Line and Monte Carlo model for passive remote sensing of cirrus and polar clouds

NASA Astrophysics Data System (ADS)

Fomin, Boris; Falaleeva, Victoria

2016-07-01

A polarized high-resolution 1-D model has been presented for TIR (Thermal Infrared) remote sensing application. It is based on the original versions of MC (Monte Carlo) and LbL (Line-by-Line) algorithms, which have shown their effectiveness when modelling the thermal radiation atmospheric transfer, taking into account, the semi-transparent Ci-type and polar clouds scattering, as well as the direct consideration of the spectra of molecular absorption. This model may be useful in the planning of satellite experiments and in the validation of similar models, which use the "k-distribution" or other approximations, to account for gaseous absorption. The example simulations demonstrate that, the selective gas absorption does not only significantly affect the absorption and emission of radiation, but also, its polarization in the Ci-type clouds. As a result, the spectra of polarized radiation contain important information about the clouds, and а high-resolution polarized limb sounding in the TIR, seems to be a useful tool in obtaining information on cloud types and their vertical structures.

Validation of Atmosphere/Ionosphere Signals Associated with Major Earthquakes by Multi-Instrument Space-Borne and Ground Observations

NASA Technical Reports Server (NTRS)

Ouzounov, Dimitar; Pulinets, Sergey; Hattori, Katsumi; Parrot, Michel; Liu, J. Y.; Yang, T. F.; Arellano-Baeza, Alonso; Kafatos, M.; Taylor, Patrick

2012-01-01

The latest catastrophic earthquake in Japan (March 2011) has renewed interest in the important question of the existence of pre-earthquake anomalous signals related to strong earthquakes. Recent studies have shown that there were precursory atmospheric/ionospheric signals observed in space associated with major earthquakes. The critical question, still widely debated in the scientific community, is whether such ionospheric/atmospheric signals systematically precede large earthquakes. To address this problem we have started to investigate anomalous ionospheric / atmospheric signals occurring prior to large earthquakes. We are studying the Earth's atmospheric electromagnetic environment by developing a multisensor model for monitoring the signals related to active tectonic faulting and earthquake processes. The integrated satellite and terrestrial framework (ISTF) is our method for validation and is based on a joint analysis of several physical and environmental parameters (thermal infrared radiation, electron concentration in the ionosphere, lineament analysis, radon/ion activities, air temperature and seismicity) that were found to be associated with earthquakes. A physical link between these parameters and earthquake processes has been provided by the recent version of Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model. Our experimental measurements have supported the new theoretical estimates of LAIC hypothesis for an increase in the surface latent heat flux, integrated variability of outgoing long wave radiation (OLR) and anomalous variations of the total electron content (TEC) registered over the epicenters. Some of the major earthquakes are accompanied by an intensification of gas migration to the surface, thermodynamic and hydrodynamic processes of transformation of latent heat into thermal energy and with vertical transport of charged aerosols in the lower atmosphere. These processes lead to the generation of external electric currents in specific regions of the atmosphere and the modifications, by dc electric fields, in the ionosphere-atmosphere electric circuit. We retrospectively analyzed temporal and spatial variations of four different physical parameters (gas/radon counting rate, lineaments change, long-wave radiation transitions and ionospheric electron density/plasma variations) characterizing the state of the lithosphere/atmosphere coupling several days before the onset of the earthquakes. Validation processes consist in two phases: A. Case studies for seven recent major earthquakes: Japan (M9.0, 2011), China (M7.9, 2008), Italy (M6.3, 2009), Samoa (M7, 2009), Haiti (M7.0, 2010) and, Chile (M8.8, 2010) and B. A continuous retrospective analysis was preformed over two different regions with high seismicity- Taiwan and Japan for 2003-2009. Satellite, ground surface, and troposphere data were obtained from Terra/ASTER, Aqua/AIRS, POES and ionospheric variations from DEMETER and COSMIC-I data. Radon and GPS/TEC were obtaining from monitoring sites in Taiwan, Japan and Italy and from global ionosphere maps (GIM) respectively. Our analysis of ground and satellite data during the occurrence of 7 global earthquakes has shown the presence of anomalies in the atmosphere. Our results for Tohoku M9.0 earthquake show that on March 7th, 2011 (4 days before the main shock and 1 day before the M7.2 foreshock of March 8, 2011) a rapid increase of emitted infrared radiation was observed by the satellite data and an anomaly was developed near the epicenter. The GPS/TEC data indicate an increase and variation in electron density reaching a maximum value on March 8. From March 3 to 11 a large increase in electron concentration was recorded at all four Japanese ground-based ionosondes, which returned to normal after the main earthquake. Similar approach for analyzing atmospheric and ionospheric parameters has been applied for China (M7.9, 2008), Italy (M6.3, 2009), Samoa (M7, 2009), Haiti (M7.0, 2010) and Chile (M8.8, 2010) eahquakes. Results have revealed the presence of related variations of these parameters implying their connection with the earthquake process. The second phase (B) of this validation included 102 major earthquakes (M>5.9) in Taiwan and Japan. We have found anomalous behavior before all of these events with no false negatives. False alarm ratio for false positives is less then 10% and has been calculated for the same month of the earthquake occurrence for the entire period of analysis (2003-2009). The commonalities for detecting atmospheric/ionospheric anomalies are: i.) Regularly appearance over regions of maximum stress (i.e., along plate boundaries); ii.) Anomaly existence over land and sea; and iii) association with M>5.9 earthquakes not deeper than 100km. Due to their long duration over the same region these anomalies are not consistent with a meteorological origin. Our initial results from the ISTF validation of multi-instrument space-borne and ground observations show a systematic appearance of atmospheric anomalies near the epicentral area, one to seven (average) days prior to the largest earthquakes, and suggest that it could be explained by a coupling process between the observed physical parameters and the pre-earthquake preparation processes.

A multi-scale hybrid neural network retrieval model for dust storm detection, a study in Asia

NASA Astrophysics Data System (ADS)

Wong, Man Sing; Xiao, Fei; Nichol, Janet; Fung, Jimmy; Kim, Jhoon; Campbell, James; Chan, P. W.

2015-05-01

Dust storms are known to have adverse effects on human health and significant impact on weather, air quality, hydrological cycle, and ecosystem. Atmospheric dust loading is also one of the large uncertainties in global climate modeling, due to its significant impact on the radiation budget and atmospheric stability. Observations of dust storms in humid tropical south China (e.g. Hong Kong), are challenging due to high industrial pollution from the nearby Pearl River Delta region. This study develops a method for dust storm detection by combining ground station observations (PM10 concentration, AERONET data), geostationary satellite images (MTSAT), and numerical weather and climatic forecasting products (WRF/Chem). The method is based on a hybrid neural network (NN) retrieval model for two scales: (i) a NN model for near real-time detection of dust storms at broader regional scale; (ii) a NN model for detailed dust storm mapping for Hong Kong and Taiwan. A feed-forward multilayer perceptron (MLP) NN, trained using back propagation (BP) algorithm, was developed and validated by the k-fold cross validation approach. The accuracy of the near real-time detection MLP-BP network is 96.6%, and the accuracies for the detailed MLP-BP neural network for Hong Kong and Taiwan is 74.8%. This newly automated multi-scale hybrid method can be used to give advance near real-time mapping of dust storms for environmental authorities and the public. It is also beneficial for identifying spatial locations of adverse air quality conditions, and estimates of low visibility associated with dust events for port and airport authorities.

The atmosphere- and hydrosphere-correlated signals in GPS observations

NASA Astrophysics Data System (ADS)

Bogusz, Janusz; Boy, Jean-Paul; Klos, Anna; Figurski, Mariusz

2015-04-01

The circulation of surface geophysical fluids (e.g. atmosphere, ocean, continental hydrology, etc.) induces global mass redistribution at the Earth's surface, and then surface deformations and gravity variations. The deformations can be reliably recorded by permanent GPS observations nowadays. The loading effects can be precisely modelled by convolving outputs from global general circulation models and Green's functions describing the Earth's response. Previously published papers showed that either surface gravity records or space-based observations can be efficiently corrected for atmospheric loading effects using surface pressure fields from atmospheric models. In a similar way, loading effects due to continental hydrology can be corrected from precise positioning observations. We evaluated 3-D displacement at the selected ITRF2008 core sites that belong to IGS (International GNSS Service) network due to atmospheric, oceanic and hydrological circulation using different models. Atmospheric and induced oceanic loading estimates were computed using the ECMWF (European Centre for Medium Range Weather Forecasts) operational and reanalysis (ERA interim) surface pressure fields, assuming an inverted barometer ocean response or a barotropic ocean model forced by air pressure and winds (MOG2D). The IB (Inverted Barometer) hypothesis was classically chosen, in which atmospheric pressure variations are fully compensated by static sea height variations. This approximation is valid for periods exceeding typically 5 to 20 days. At higher frequencies, dynamic effects cannot be neglected. Hydrological loading were provided using MERRA land (Modern-Era Retrospective Analysis for Research and Applications - NASA reanalysis for the satellite era using a major new version of the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5)) for the different stations. After that we compared the results to the GPS-derived time series of North, East and Up components. The analysis of satellite data was performed twofold: firstly, the time series from network solution (NS) processed in Bernese 5.0 software by the Military University of Technology EPN Local Analysis Centre, secondly, the ones from PPP (Precise Point Positioning) from JPL (Jet Propulsion Laboratory) processing in Gipsy-Oasis were analyzed. Both were modelled with wavelet decomposition with Meyer orthogonal mother wavelet. Here, nine levels of decomposition were applied and eighth detail of it was interpreted as changes close to one year. In this way, both NS and PPP time series where presented as curves with annual period with amplitudes and phases changeable in time. The same analysis was performed for atmospheric (ATM) and hydrospheric (HYDR) models. All annual curves (modelled from NS, PPP, ATM and HYDR) were then compared to each other to investigate whether GPS observations contain the atmosphere and hydrosphere correlated signals and in what way the amplitudes of them may disrupt the GPS time series.