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Polar Vortex Outbreak Air Transport: Observation using Satellite IR Sounder Derived Ozone Product and Comparison with Model

The Single Field of View (SFOV) Sounder Atmospheric Products (SiFSAP) derived from Cross-track Infrared Sounder (CrIS) on SNPP and JPSS have a spatial resolution ( ~14.5 km) better than most global weather and climate models. Most recent significant improvement in the quality of these products enables us to use these high-resolution observation-based sounding data for weather studies and model evaluation. The aim of this study is to explore the value to use these SFOV products for studying the dynamic transport associated with polar vortex outbreak. In a few cases studies, we used SiFSAP products, especially ozone, as well as the data of wind, geopotential height (GPH) and potential velocity (PV) from the fifth-generation ECMWF reanalysis (ERA5) data, to analyze the variation of total ozone, relative humidity and ozone in different layers, as well as their correlation with GPH and PV. Some comparison of the retrieved temperature and water vapor with ERA5 data, and ozone with the Ozone Mapping and Profiler Suite (OMPS) measurements have also been made. It is found (1) the transport of O3-riched polar air accompanying the polar vortex breakup to lower latitude and lower atmosphere, and (2) the transport path of O3 agreeing well with the path of polar cold air (illustrated using the retrieved RH, wind fields and GPH). These results demonstrate the 3-D structure of O3 distribution as derived from CrIS measurements provides some insights of the cold air transport, and can be used to track the dynamic transport of polar cold air following the outbreak of polar vortex. The observed enhancement of O3 following the polar vortex outbreak also suggests some possible linkage between the tropospheric cold air advected with stratospheric air source.

Xiaozhen Xiong↗
NASA NTRS2005

A Model of the Effect of Ozone Depletion on Lower-Stratospheric Structure

We have run two twenty-year integrations of a global circulation model using 1978-1980 and 1998-2000 monthly mean ozone climatologies. The ozone climatology is used solely in the radiation scheme of the model. Several key differences between the model runs will be presented. The temperature and potential vorticity (PV) structure of the lower stratosphere, particularly in the Southern Hemisphere, is significantly changed using the 1998-2000 ozone climatology. In the Southern Hemisphere summer, the lapse rate and PV-defined polar tropopauses are both at altitudes on the order of several hundred meters greater than the 1978-1980 climatological run. The 380 K potential temperature surf= is likewise at a greater altitude. The mass of the extratropical lowermost stratosphere (between the tropopause and 380 K surface) remains unchanged. The altitude differences are not observed in the Northern Hemisphere. The different ozone fields do not produce a significant change in the annual extratropical stratosphere-troposphere exchange of mass although slight variations in the spatial distribution of the exchange exist. We are also investigating a delay in the breakup of the Southern Hemisphere polar vortex due to the differing ozone climatologies.

Olsen, Mark A.↗
NASA NTRS1999

Aircraft NO(x) had no Unique Fingerprint on Sonex; Lightning Dominated Fresh NO(x) Sources

Key questions to which SONEX was directed were the following: Can aircraft corridors be detected? Is there a unique tracer for aircraft NO(x)? Can a "background" NO(x) (or NO(y) be defined? What fraction of NO(x) measured during SONEX was from aircraft? How representative was SONEX of the North Atlantic in 1997 and how typical of other years? We attempt to answer these questions through species-species correlations, probability distribution functions (PDFs), and meteorological history. There is not a unique aircraft tracer, largely due to the high variability of air mass origins and tracer ratios, which render "average" quantities meaningless. The greatest NO and NO(y) signals were associated with lightning and convective NO sources. Well-defined background CO, NO(y) and NO(y)/ozone ratio appear in subsets of two cross-track flights with subtropical origins and five flights with predominantly mid-latitude air. Forty percent of the observations on these 7 flights showed NO(y)/ozone to be above background, evidently due to unreacted NO(x). This NO(x) is a combination of aircraft, lightning and surface pollution injected by convection. The strongly subtropical signatures in SONEX observations, confirmed by pv (potential vorticity) values along flight tracks, argues for most of the unreacted NO(x) originating from lightning. Potential vorticity statistics along SONEX flight tracks in 1992-1998, and for the North Atlantic as a whole, show the SONEX meteorological environment to be representative of the North Atlantic flight corridor in the October-November period.

Thompson, A.↗
NASA NTRS2018

Age of Martian Air: Time Scales for Martian Atmospheric Transport

The mean time since air in the Martian atmosphere was in the low-latitude boundary layer is examined using simulations of an idealized “mean age” tracer with the MarsWRF general circulation model. The spatial distribution and seasonality of the mean age in low- and mid-latitudes broadly follow contours of the mean meridional circulation, with the mean age increasing from 0 at the surface to a maximum of 60–100 sols in the upper atmosphere. Substantially older mean ages (exceeding 300 sols) are found in polar regions, with oldest ages in the lower atmosphere (10–100 Pa), above a near-surface layer with very young ages (around 20 sols). The annual maximum ages occur around the equinoxes, and the age in the polar lower atmosphere decreases during the autumn to winter transition. This autumn-winter decrease in age occurs because of mixing of polar and mid-latitude air when the polar vortex exhibits an annulus of high potential vorticity (PV) with a local minimum near the pole. There is no autumn-winter decrease and old ages persist throughout autumn and winter in simulations with CO2 phase changes disabled, and thus no latent heating, where there is a monopolar vortex (i.e., a monotonic increase in PV from equator to pole) forms. The altitudinal and seasonal variations in the mean age indicates similar variations in the transport of dust into polar regions and the mixing of polar air (with, e.g., low water vapor and high ozone concentrations during winter) into mid-latitudes.

Waugh, D. W.↗
NASA NTRS2004

Isentropic Cross-Tropopause Ozone Transport in the Northern Hemisphere

This paper investigates isentropic ozone exchange between the extratropical lower stratosphere and the subtropical upper troposphere in the Northern Hemisphere. The quantification method is based on the potential vorticity (PV) mapping of Stratospheric Aerosol and Gas Experiment (SAGE)-II ozone measurements and contour advection calculations using the NASA Goddard Space Center Data Assimilation Office (DAO) analysis for the year 1990. The magnitude of the annual isentropic stratosphere-to-troposphere ozone flux is calculated to be approximately twice the flux that is directed from the troposphere into the stratosphere. The net effect is that approx.46 x 10(exp 9) kg/yr of ozone are transferred quasi horizontally from the extratropical lower stratosphere into the subtropical upper troposphere between the isentropic surfaces of 330 and 370 K. The estimated monthly ozone fluxes show that the isentropic cross-tropopause ozone transport is stronger in summer/fall than in winter/ spring, and this seasonality is more obvious at the upper three levels (i.e., 345, 355, and 365 K) than at 335 K. The distributions of the estimated monthly ozone fluxes indicate that the isentropic stratosphere-to-troposphere ozone exchange is associated with wave breaking and occurs preferentially over the eastern Atlantic Ocean and northwest Africa in winter and over the Atlantic and Pacific Oceans in summer.

Jing, P.↗
NASA NTRS1999

Transport of Passive Tracers in Baroclinic Wave Life Cycles

The transport of passive tracers in idealized baroclinic wave life cycles is studied using output from the National Center for Atmospheric Research Community Climate Model (CCM2). Two life cycles, LCn and LCs, are simulated, starting with baroclinically unstable initial conditions similar to those used by Thorncroft et al. in their study of two life cycle paradigms. The two life cycles LCn and LCs have different initial horizontal wind shear structures that result in distinctive nonlinear development. In terms of potential vorticity-potential temperature (PV-theta) diagnostics, the LCn case is characterized by thinning troughs that are advected anti-cyclonically and equatorward, while the LCs case has broadening troughs that wrap up cyclonically and poleward. Four idealized passive tracers are included in the model to be advected by the semi-Lagrangian transport scheme of the CCM2, and their evolutions are investigated throughout the life cycles. Tracer budgets are analyzed in terms of the transformed Eulerian mean constituent transport formalism in pressure coordinates and also in isentropic coordinates. Results for both LCn and LCs show transport that is downgradient with respect to the background structure of the tracer field, but with a characteristic spatial structure that maximizes in the middle to high latitudes. For the idealized tropospheric tracers in this study, this represents a net upward and poleward transport that enhances concentrations at high latitudes. These results vary little with the initial distribution of the constituent field. The time tendency of the tracer is influenced most strongly by the eddy flux term. with the largest transport occurring during the nonlinear growth stage of the life cycle. The authors also study the transport of a lower-stratospheric tracer, to examine stratosphere-troposphere exchange for baroclinic waves.

Stone, Elizabeth M.↗
NASA NTRS2015

Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H2 from Cassini Far-IR Spectroscopy

Far-IR 16-1000 micrometer spectra of Saturn's hydrogen-helium continuum measured by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a near-continuous record of upper tropospheric (70-700 mbar) temperatures and para-H2 fraction as a function of latitude, pressure and time for a third of a saturnian year (2004-2014, from northern winter to northern spring). The thermal field reveals evidence of reversing summertime asymmetries superimposed onto the belt/zone structure. The temperature structure is almost symmetric about the equator by 2014, with seasonal lag times that increase with depth and are qualitatively consistent with radiative climate models. Localised heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation to the temperature profile that shifts in magnitude and location, declining in the autumn hemisphere and growing in the spring. Changes in the para-H2 (f(sub p)) distribution are subtle, with a 0.02-0.03 rise over the spring hemisphere (200-500 mbar) perturbed by (i) low-f(sub p) air advected by both the springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of high-f(sub p) air at northern high latitudes, responsible for a developing north-south asymmetry in f(sub p). Conversely, the shifting asymmetry in the para-H2 disequilibrium primarily reflects the changing temperature structure (and hence the equilibrium distribution of f(sub p)), rather than actual changes in f(sub p) induced by chemical conversion or transport. CIRS results interpolated to the same point in the seasonal cycle as re-analysed Voyager-1 observations (early northern spring) show qualitative consistency from year to year (i.e., the same tropospheric asymmetries in temperature and f(sub p)), with the exception of the tropical tropopause near the equatorial zones and belts, where downward propagation of a cool temperature anomaly associated with Saturn's stratospheric oscillation could potentially perturb tropopause temperatures, para-H2 and winds. Quantitative differences between the Cassini and Voyager epochs suggest that the oscillation is not in phase with the seasonal cycle at these tropospheric depths (i.e., it should be described as quasi-periodic rather than 'semi annual'). Variability in the zonal wind field derived from latitudinal thermal gradients is small (less than 10 m/s per scale height near the tropopause) and mostly affects the broad retrograde jets, with the notable exception of large variability on the northern flank of the equatorial jet. The meridional potential vorticity (PV) gradient, and hence the 'staircase of PV' associated with spatial variations in the vigour of vertical mixing, has varied over the course of the mission but maintained its overall shape. PV gradients in latitude and altitude are used to estimate the atmospheric refractive index for the propagation of stationary planetary (Rossby) waves, predicting that such wave activity would be confined to regions of real refractivity (tropical regions plus bands at 35-45 in both hemispheres). The penetration depth of these regions into the upper troposphere is temporally variable (potentially associated with stratification changes), whereas the latitudinal structure is largely unchanged over time (associated with the zonal jet system).

Fletcher, Leigh N.↗
NASA NTRS2006

Modular, Reconfigurable, High-Energy Technology Development

The Modular, Reconfigurable High-Energy (MRHE) Technology Demonstrator project was to have been a series of ground-based demonstrations to mature critical technologies needed for in-space assembly of a highpower high-voltage modular spacecraft in low Earth orbit, enabling the development of future modular solar-powered exploration cargo-transport vehicles and infrastructure. MRHE was a project in the High Energy Space Systems (HESS) Program, within NASA's Exploration Systems Research and Technology (ESR&T) Program. NASA participants included Marshall Space Flight Center (MSFC), the Jet Propulsion Laboratory (JPL), and Glenn Research Center (GRC). Contractor participants were the Boeing Phantom Works in Huntsville, AL, Lockheed Martin Advanced Technology Center in Palo Alto, CA, ENTECH, Inc. in Keller, TX, and the University of AL Huntsville (UAH). MRHE's technical objectives were to mature: (a) lightweight, efficient, high-voltage, radiation-resistant solar power generation (SPG) technologies; (b) innovative, lightweight, efficient thermal management systems; (c) efficient, 100kW-class, high-voltage power delivery systems from an SPG to an electric thruster system; (d) autonomous rendezvous and docking technology for in-space assembly of modular, reconfigurable spacecraft; (e) robotic assembly of modular space systems; and (f) modular, reconfigurable distributed avionics technologies. Maturation of these technologies was to be implemented through a series of increasingly-inclusive laboratory demonstrations that would have integrated and demonstrated two systems-of-systems: (a) the autonomous rendezvous and docking of modular spacecraft with deployable structures, robotic assembly, reconfiguration both during assembly and (b) the development and integration of an advanced thermal heat pipe and a high-voltage power delivery system with a representative lightweight high-voltage SPG array. In addition, an integrated simulation testbed would have been developed containing software models representing the technologies being matured in the laboratory demos. The testbed would have also included models for non-MRHE developed subsystems such as electric propulsion, so that end-to-end performance could have been assessed. This paper presents an overview of the MRHE Phase I activities at MSFC and its contractor partners. One of the major Phase I accomplishments is the assembly demonstration in the Lockheed Martin Advanced Technology Center (LMATC) Robot-Satellite facility, in which three robot-satellites successfully demonstrated rendezvous & docking, self-assembly, reconfiguration, adaptable GN&C, deployment, and interfaces between modules. Phase I technology maturation results from ENTECH include material recommendations for radiation hardened Stretched Lens Array (SLA) concentrator lenses, and a design concept and test results for a hi-voltage PV receiver. UAH's accomplishments include Supertube heatpipe test results, which support estimates of thermal conductivities at 30,000 times that of an equivalent silver rod. MSFC performed systems trades and developed a preliminary concept design for a 100kW-class modular reconfigurable solar electric propulsion transport vehicle, and Boeing Phantom Works in Huntsville performed assembly and rendezvous and docking trades. A concept animation video was produced by SAIC, wllich showed rendezvous and docking and SLA-square-rigger deployment in LEO.

Carrington, Connie↗
NASA NTRS2010

Mineralogy and Thermal Properties of V-Type Asteroid 956 Elisa: Evidence for Diogenitic Material from the Spitzer IRS (5-35 Micrometers) Spectrum

We present the thermal infrared (5-35 micrometer) spectrum of 956 Elisa as measured by the Spitzer Infrared Spectrograph ("IRS"; Houck,1.R. et .11. [20041. Astrophys, 1. SuppL 154, 18-24) together with new ground-based lightcurve data and near-IR spectra. From the visible lightcurve photometry, we determine a rotation period of 16.494 +/- 0.001 h, identify the rotational phase of the Spitzer observations, and estimate the visible absolute magnitude (Hv) at that rotational phase to be 12.58 +/- 0.04. From radiometric analysis of the thermal flux spectrum, we find that at the time of observation 956 Elisa had a projected radius of 5.3 +/- 0.4 km with a visible albedo pv = 0.142+/- 0.022, significantly lower than that of the prototype V-type asteroid, 4 Vesta. (This corresponds to a radius of 5.2 +/- 0.4 km at lightcurve mean.) Analysis with the standard thermal model (STM) results in a sub-solar temperature of 292.3 +/- 2.8 K and beaming parameter eta = 1.16 +/- 0.05. Thermophysical modeling places a lower limit of 20 J m(exp -2)K(exp -1)s(exp -1/2) on the thermal inertia of the asteroid's surface layer (if the surface is very smooth) but more likely values fall between 30 and 150 J m(exp -2)K(exp -1)s(exp -1/2) depending on the sense of rotation. The emissivity spectrum, calculated by dividing the measured thermal flux spectrum by the modeled thermal continuum, exhibits mineralogically interpretable spectral features within the 9-12 micrometer reststrahlen band, the 15-16.5 micrometer Si-O-Si stretching region, and the 16-25 micrometer reststrahlen region that are consistent with pyroxene of diogenitic composition: extant diogenitic pyroxenes fall within the narrow compositional range W0(sub 2+/-1)En(sub 74+/-2)Fs(sub 24+/-1). Spectral deconvolution of the 9-12 micrometer reststrahlen features indicates that up to approximately 20% olivine may also be present, suggesting an olivine-diogenite-like mineralogy. The mid-IR spectrum is inconsistent with non-cumulate eucrite as the major component on the surface of 956 Elisa, although cumulate eucrite material may be present at abundances lower than that of the diogenite component. Analysis of new near-IR spectra of 956 Elisa with the Modified Gaussian Model (MGM; Sunshine, J,M., Pieters, C.M., Pratt, S.F.[1990]. J. Geophys. Res, 95 (May), 6955-6966) results in two pyroxene compositions: 75% magnesian low-Ca pyroxene and 25% high-Ca pyroxene. High-Ca pyroxene is not evident in the mid-IR data, but may belong to a component that is underrepresented in the mid-IR spectrum either because of its spatial distribution on the asteroid or because of its particle size. High-Ca pyroxenes that occur as exsolution lamellae may also be more evident spectrally in the NIR than in the mid-IR. In any case, we find that the mid-IR spectrum of 956 Elisa is dominated by emission from material of diogenite- like composition, which has very rarely been observed among asteroids.

Lim, Lucy F.↗