Comparative studies of atmospheric density models used for earth satellite orbit estimation
Previously cited in issue 19, p. 2986, Accession no. A82-38879
Shanklin, R. E., Jr.↗
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Middle Atmosphere Reference Model Derived from Satellite Data
Zonally averaged temperature and geostrophic zonal wind for each month and for latitudes from 80 S to 80 N with pressure scale height as a vertical coordinate are given tabular form. The pressure scale height is defined as -ln (p/P sub O) where p is pressure and P sub O is surface pressure. The height interval corresponding to one pressure scale height is proportional to absolute temperature, and is 7 km at 240 K. Values in are given at intervals of 0.5 pressure scale heights, i.e., approximately 3,5 km. The geopotential height fields for the principal seasons are given. Temperature, pressure and density with geometric height as the vertical coordinate at invervals of 5 km. The temperature values were obtained from a combination of satellite data above 30 mb with values supplied by the Berlin Free University at 30 mb and the climatology derived by OORT (1983) for 50 mb and below. The geopotential height fields were obtained from these temperature fields by integrating up and down from the 30 mb geopotential height supplied by Berlin Free University. The geostrophic winds were obtained by differentiating these geopotential height fields.
Barnett, J. J.↗
Annual and Semiannual Cycles Based on the Middle Atmosphere Reference Model
The SCR/PMR monthly temperature mean values were Fourier analysed at each latitude and pressure level to obtain the annual mean and the amplitude and phase of the annual and semiannual cycles. The phase is the month of the maximum, such that 1 = January 1, 1.5 = January 16, 2 = February 1, etc. Some very marked hemispheric differences noted are: (1) at 80 N there is a maximum amplitude of the annual cycle of 26 K at 2.5 mb, the corresponding maximum at 80 S is much stronger (35 K) and at a lower altitude (11 mb); (2) the semiannual amplitudes show the well known maximum over the tropics in the upper stratosphere, but also maxima at high latitudes; and (3) the annual mean shows a minimum at 50 S, 1 mb, and a corresponding weaker minimum at 60 N. In general, the hemispheres are remarkably similar and six months out of phase above about 0.3 mb (56 km). The two hemispheres are significantly different especially in winter after allowing for a six month shift. Changes rom summer to winter are so large by comparison that the annual cycles appear to be very similar.
Barnett, J. J.↗
Atmospheric electrical modeling in support of the NASA F106 Storm Hazards Project
With the use of composite (non-metallic) and microelectronics becoming more prevalent in the construction of both military and commercial aircraft, the control systems have become more susceptible to damage or failure from electromagnetic transients. One source of such transients is the lightning discharge. In order to study the effects of the lightning discharge on the vital components of an aircraft, NASA Langley Research Center has undertaken a Storm Hazards Program in which a specially instrumented F106B jet aircraft is flown into active thunderstorms with the intention of being struck by lightning. One of the specific purposes of the program is to quantify the environmental conditions which are conductive to aircraft lightning strikes.
Helsdon, J. H.↗
NORAD/SPACECMD comments concerning the atmospheric density models
Recent models do not produce more accurate neutral densities (although they require more computer time), regardless of the level of solar activity. This implies that there has been no measurable improvement of the calculation of neutral density since the early 60s. With known solar flux and geomagnetic activity (Ap) inputs, the density evaluation needs improvement. For highly eccentric orbits which span low to high altitude, the accuracy generated which has an altitude limitation of 1000 km remains comparable with those obtained by more recent models. This implies that either the density at 1000 km and above is insignificant or that the values provided by the recent models at high altitudes may not be reliable or both. Prediction accuracies obtained through the use of precision data from the Defense Mapping Agency are generally comparable to those obtained by using operational sensor data. This implies that the prediction accuracy problem is not necessarily caused by less accurate observations. The definition of the mean solar flux F10.7 is not universal.
Liu, Joseph J. F.↗
Atmospheric Electrical Modeling in Support of the NASA F-106 Storm Hazards Project
A recently developed storm electrification model (SEM) is used to investigate the operating environment of the F-106 airplane during the NASA Storm Hazards Project. The model is 2-D, time dependent and uses a bulkwater microphysical parameterization scheme. Electric charges and fields are included, and the model is fully coupled dynamically, microphysically and electrically. One flight showed that a high electric field was developed at the aircraft's operating altitude (28 kft) and that a strong electric field would also be found below 20 kft; however, this low-altitude, high-field region was associated with the presence of small hail, posing a hazard to the aircraft. An operational procedure to increase the frequency of low-altitude lightning strikes was suggested. To further the understanding of lightning within the cloud environment, a parameterization of the lightning process was included in the SEM. It accounted for the initiation, propagation, termination, and charge redistribution associated with an intracloud discharge. Finally, a randomized lightning propagation scheme was developed, and the effects of cloud particles on the initiation of lightning investigated.
Helsdon, John H., Jr.↗
Group-kinetic theory and modeling of atmospheric turbulence
A group kinetic method is developed for analyzing eddy transport properties and relaxation to equilibrium. The purpose is to derive the spectral structure of turbulence in incompressible and compressible media. Of particular interest are: direct and inverse cascade, boundary layer turbulence, Rossby wave turbulence, two phase turbulence; compressible turbulence, and soliton turbulence. Soliton turbulence can be found in large scale turbulence, turbulence connected with surface gravity waves and nonlinear propagation of acoustical and optical waves. By letting the pressure gradient represent the elementary interaction among fluid elements and by raising the Navier-Stokes equation to higher dimensionality, the master equation was obtained for the description of the microdynamical state of turbulence.
Tchen, C. M.↗
Recent improvements in atmospheric environment models for Space Station applications
The capability of empirical models of the earth's thermosphere must continually be updated if they are to keep pace with their many applications in the aerospace industry. This paper briefly summarizes the progress of several such efforts in support of the Space Station Program. The efforts consists of the development of data bases, analytical studies of the data, and evaluation and intercomparison of thermosphere models. A geomagnetic storm model of Slowey does not compare as well to the MSIS-86 model as does the Marshall Engineering Thermosphere (MET). LDEF orbit decay data is used to evaluate the performance of the MET and MSIS-86 during a period of high solar activity; equal to or exceeding the highest levels that existed during the time of the original data sets upon which these models are based.
Anderson, B. Jeffrey↗
The chlorine budget of the present-day atmosphere - A modeling study
The contribution of source gases to the total amount of inorganic chlorine (ClY) is examined analytically with a time-dependent model employing 11 source gases. The source-gas emission data are described, and the modeling methodology is set forth with attention given to the data interpretation. The abundances and distributions are obtained for all 11 source gases with corresponding ClY production rates and mixing ratios. It is shown that the ClY production rate and the ClY mixing ratio for each source gas are spatially dependent, and the change in the relative contributions from 1950 to 1990 is given. Ozone changes in the past decade are characterized by losses in the polar and midlatitude lower stratosphere. The values for CFC-11, CCl4, and CH3CCl3 suggest that they are more evident in the lower stratosphere than is suggested by steady-state estimates based on surface concentrations.
Weisenstein, Debra K.↗
Atmospheric numerical modeling resource enhancement and model convective parameterization/scale interaction studies
Research will be undertaken in this contract in the area of Modeling Resource and Facilities Enhancement to include computer, technical and educational support to NASA investigators to facilitate model implementation, execution and analysis of output; to provide facilities linking USRA and the NASA/EADS Computer System as well as resident work stations in ESAD; and to provide a centralized location for documentation, archival and dissemination of modeling information pertaining to NASA's program. Additional research will be undertaken in the area of Numerical Model Scale Interaction/Convective Parameterization Studies to include implementation of the comparison of cloud and rain systems and convective-scale processes between the model simulations and what was observed; and to incorporate the findings of these and related research findings in at least two refereed journal articles.
Cushman, Paula P.↗
Comparison and analysis of aircraft measurements and mesoscale atmospheric chemistry model simulations of tropospheric ozone
The Regional Acid Deposition Model (RADM) has been applied to several of the field experiments which were part of the Acid Models Operational and Diagnostic Evaluation Study (Acid MODES). The experiment which was of particular interest with regards to ozone photochemistry involved horizontal zig-zag flight patterns (ZIPPER) over an area from the eastern Ohio River valley to the Adirondacks of New York. Model simulations by both the standard resolution RADM (delta x = 80 km) and the nested grid RADM (delta x = 26.7 km) compare well to measurements in the low emission regions in central Pennsylvania and upstate New York, but underestimate in the high emission upper Ohio River valley. The nested simulation does considerably better, however, than the coarse grid simulation in terms of horizontal pattern and concentration magnitudes. Analysis of NO(x) and HO(x) concentrations and photochemical products rates of ozone show that the model's response to large point source emissions is very unsystematic both spatially and temporally. This is due to the models instability to realistically simulate the small scale (subgrid) gradients in precursor concentrations in and around large point source plumes.
Pleim, Jonathan E.↗
What can we learn from relaxation measurements of a laser-perturbed atmosphere? A modeling study
The chemical kinetic aspects of a transient increase in OH and HO2 by several orders of magnitude are explored in three model tropospheres. This chemical kinetic modeling effort was undertaken to support the operation of a pump-and-probe LIDAR instrument. A powerful excimer laser pulse perturbs the troposphere after which its relaxation back to steady state is examined by remote sensing, for example by DIAL or LIF. Instead of probing ambient levels of key free radicals, a study of the relaxation kinetics in real time enables chemical mechanistic studies in situ.
Clericetti, Agostino↗
In situ measurements of the NO2/NO ratio for testing atmospheric photochemical models
Simultaneous in situ measurements of NO2, NO, O3, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test our current understanding of the photochemistry of the lower stratospere. Data were collected from several flights of the ER-2 aircraft at mid-latitudes in May 1993 during NASA's Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE). The daytime ratio of NO2/NO remains fairly constant at 19 km with a typical value of 0.68 and standard deviation of +/- 17. The ratio observations are compared with simple steady-state calculations based on laboratory-measured reaction rates and modeled NO2 photolysis rates. At each measurement point the daytime NO2/NO with its measurements uncertainty overlap the results of steady-state caculations and associated uncertainty. Possible sources of error are examined in both model and measurements. It is shown that more accurate laboratory determinations of the NO + 03 reaction rate and of the NO2 cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of our knowledge of NO(X) phtochemistry by reducing significant sources if uncertainties in the interpretation of statospheric measurements.
Jaegle, L.↗
In Situ Measurements of the NO2/NO Ratio for Testing Atmospheric Photochemical Models
Simultaneous in situ measurements of NO2, NO, O3, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test our current understanding of the photochemistry of the lower stratosphere. Data were collected from several flights of the ER-2 aircraft at mid-latitudes in May 1993 during NASA's Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE). The daytime ratio of NO2/NO remains fairly constant at 19 km with a typical value of 0.68 and standard deviation of +/- 0.17. The ratio observations are compared with simple steady-state calculations based on laboratory-measured reaction rates and modeled NO2 photolysis rates. At each measurement point the daytime NO2/NO with its measurement uncertainty overlap the results of steady-state calculations and associated uncertainty. However, over all the ER-2 flights examined, the model systematically overestimates the ratio by 40% on average. Possible sources of error are examined in both model and measurements. It is shown that more accurate laboratory determinations of the NO + O3 reaction rate and of the NO2 cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of our knowledge of NO(x) photochemistry by reducing significant sources of uncertainties in the interpretation of stratospheric measurements. The present measurements are compared with earlier observations of the ratio at higher altitudes.
Jaegle, L.↗
Use of Geostationary Satellite Data to Force Land Surface Schemes within Atmospheric Mesoscale Models
A technique has been developed for assimilating GOES-derived skin temperature tendencies and insolation into the surface energy budget equation of a mesoscale model so that the simulated rate of temperature change closely agrees with the satellite observations. A critical assumption of the technique is that the availability of moisture (either from the soil or vegetation) is the least known term in the model's surface energy budget. Therefore, the simulated latent heat flux, which is a function of surface moisture availability, is adjusted based upon differences between the modeled and satellite-observed skin temperature tendencies. An advantage of this technique is that satellite temperature tendencies are assimilated in an energetically consistent manner that avoids energy imbalances and surface stability problems that arise from direct assimilation of surface shelter temperatures. The fact that the rate of change of the satellite skin temperature is used rather than the absolute temperature means that sensor calibration is not as critical. The technique has been employed on a semi-operational basis at the GHCC within the PSU/NCAR MM5. Assimilation has been performed on a grid centered over the Southeastern US since November 1998. Results from the past year show that assimilation of the satellite data reduces both the bias and RMSE for simulations of surface air temperature and relative humidity. These findings are based on comparison of assimilation runs with a control using the simple 5-layer soil model available in MM5. A significant development in the past several months was the inclusion of the detailed Oregon State University land surface model (OSU/LSM) as an option within MM5. One of our working hypotheses has been that the assimilation technique, although simple, may provide better short-term forecasts than a detailed LSM that requires significant number initialized parameters. Preliminary results indicate that the assimilation out performs the OSU/LSM as it is incorporated in MM5. Details will be presented at the symposium.
Lapenta, William M.↗
Topography Modeling in Atmospheric Flows Using the Immersed Boundary Method
Numerical simulation of flow over complex geometry needs accurate and efficient computational methods. Different techniques are available to handle complex geometry. The unstructured grid and multi-block body-fitted grid techniques have been widely adopted for complex geometry in engineering applications. In atmospheric applications, terrain fitted single grid techniques have found common use. Although these are very effective techniques, their implementation, coupling with the flow algorithm, and efficient parallelization of the complete method are more involved than a Cartesian grid method. The grid generation can be tedious and one needs to pay special attention in numerics to handle skewed cells for conservation purposes. Researchers have long sought for alternative methods to ease the effort involved in simulating flow over complex geometry.
Ackerman, A. S.↗
Evaluation of a Potential for Enhancing the Decision Support System of the Interagency Modeling and Atmospheric Assessment Center with NASA Earth Science Research Results
NASA's objective for the Applied Sciences Program of the Science Mission Directorate is to expand and accelerate the realization of economic and societal benefits from Earth science, information, and technology. This objective is accomplished by using a systems approach to facilitate the incorporation of Earth observations and predictions into the decision-support tools used by partner organizations to provide essential services to society. The services include management of forest fires, coastal zones, agriculture, weather prediction, hazard mitigation, aviation safety, and homeland security. In this way, NASA's long-term research programs yield near-term, practical benefits to society. The Applied Sciences Program relies heavily on forging partnerships with other Federal agencies to accomplish its objectives. NASA chooses to partner with agencies that have existing connections with end-users, information infrastructure already in place, and decision support systems that can be enhanced by the Earth science information that NASA is uniquely poised to provide (NASA, 2004).
Blonski, Slawomir↗
Modeling of Atmosphere Revitalization
NASA's AES is pioneering new approaches for future human missions beyond Earth orbit. All spacecraft systems must be minimized with respect to mass, power, and volume. Here, we show work related to improving system efficiency and reliability for water separation systems on crewed vehicles and the initial development of COMSOL simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project
Coker, Robert↗