Gone with the Wind: Three Years of MAVEN Measurements of Atmospheric Loss at Mars

NASA Astrophysics Data System (ADS)

Brain, David; MAVEN Team

2017-10-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission is making measurements of the Martian upper atmosphere and near space environment, and their interactions with energy inputs from the Sun. A major goal of the mission is to evaluate the loss of atmospheric gases to space in the present epoch, and over Martian history. MAVEN is equipped with instruments that measure both the neutral and charged upper atmospheric system (thermosphere, ionosphere, exosphere, and magnetosphere), inputs from the Sun (extreme ultraviolet flux, solar wind and solar energetic particles, and interplanetary magnetic field), and escaping atmospheric particles. The MAVEN instruments, coupled with models, allow us to more completely understand the physical processes that control atmospheric loss and the particle reservoirs for loss.Here, we provide an overview of the significant results from MAVEN over approximately 1.5 Mars years (nearly three Earth years) of observation, from November 2014 to present. We argue that the MAVEN measurements tell us that the loss of atmospheric gases to space was significant over Martian history, and present the seasonal behavior of the upper atmosphere and magnetosphere. We also discuss the influence of extreme events such as solar storms, and a variety of new discoveries and observations of the Martian system made by MAVEN.

Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

NASA Technical Reports Server (NTRS)

Williams, D. J.; Grubb, R. N.; Evans, D. S.; Sauer, H. H.

1974-01-01

The charged particle observations proposed for the new low altitude weather satellites, TIROS-N, are described that will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance in distinguishing between solar and geomagnetic activity as possible causative sources.

Ionization of the Earth's Upper Atmosphere in Large Energetic Particle Events

NASA Astrophysics Data System (ADS)

Wolff, E.; Burrows, J.; Kallenrode, M.; von Koenig, M.; Kuenzi, K. F.; Quack, M.

2001-12-01

Energetic charged particles ionize the upper terrestrial atmosphere. Sofar, chemical consequences of precipitating particles have been discussed for solar protons with energies up to a few hundred MeV. We present a refined model for the interaction of energetic particles with the atmosphere based on a Monte-Carlo simulation. The model includes higher energies and other particle species, such as energetic solar electrons. Results are presented for well-known solar events, such as July 14, 2000, and are extrapolated to extremely large events, such as Carrington's white light flare in 1859, which from ice cores has been identified ass the largest impulsive NO3 event in the interval 1561 -- 1994 (McCracken et al., 2001).

The solar-terrestrial environment. An introduction to geospace - the science of the terrestrial upper atmosphere, ionosphere and magnetosphere.

NASA Astrophysics Data System (ADS)

Hargreaves, J. K.

This textbook is a successor to "The upper atmosphere and solar-terrestrial relations" first published in 1979. It describes physical conditions in the upper atmosphere and magnetosphere of the Earth. This geospace environment begins 70 kilometres above the surface of the Earth and extends in near space to many times the Earth's radius. It is the region of near-Earth environment where the Space Shuttle flies, the aurora is generated, and the outer atmosphere meets particles streaming out of the sun. The account is introductory. The intent is to present basic concepts, and for that reason the mathematical treatment is not complex. There are three introductory chapters that give basic physics and explain the principles of physical investigation. The principal material contained in the main part of the book covers the neutral and ionized upper atmosphere, the magetosphere, and structures, dynamics, disturbances and irregularities. The concluding chapter deals with technological applications.

Temporal Variability of Atomic Hydrogen From the Mesopause to the Upper Thermosphere

NASA Astrophysics Data System (ADS)

Qian, Liying; Burns, Alan G.; Solomon, Stan S.; Smith, Anne K.; McInerney, Joseph M.; Hunt, Linda A.; Marsh, Daniel R.; Liu, Hanli; Mlynczak, Martin G.; Vitt, Francis M.

2018-01-01

We investigate atomic hydrogen (H) variability from the mesopause to the upper thermosphere, on time scales of solar cycle, seasonal, and diurnal, using measurements made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite, and simulations by the National Center for Atmospheric Research Whole Atmosphere Community Climate Model-eXtended (WACCM-X). In the mesopause region (85 to 95 km), the seasonal and solar cycle variations of H simulated by WACCM-X are consistent with those from SABER observations: H density is higher in summer than in winter, and slightly higher at solar minimum than at solar maximum. However, mesopause region H density from the Mass-Spectrometer-Incoherent-Scatter (National Research Laboratory Mass-Spectrometer-Incoherent-Scatter 00 (NRLMSISE-00)) empirical model has reversed seasonal variation compared to WACCM-X and SABER. From the mesopause to the upper thermosphere, H density simulated by WACCM-X switches its solar cycle variation twice, and seasonal dependence once, and these changes of solar cycle and seasonal variability occur in the lower thermosphere ( 95 to 130 km), whereas H from NRLMSISE-00 does not change solar cycle and seasonal dependence from the mesopause through the thermosphere. In the upper thermosphere (above 150 km), H density simulated by WACCM-X is higher at solar minimum than at solar maximum, higher in winter than in summer, and also higher during nighttime than daytime. The amplitudes of these variations are on the order of factors of 10, 2, and 2, respectively. This is consistent with NRLMSISE-00.

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.

STOCHASTIC TRANSIENTS AS A SOURCE OF QUASI-PERIODIC PROCESSES IN THE SOLAR ATMOSPHERE

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

Yuan, Ding; Walsh, Robert W.; Su, Jiangtao

2016-06-01

Solar dynamics and turbulence occur at all heights of the solar atmosphere and could be described as stochastic processes. We propose that finite-lifetime transients recurring at a certain place could trigger quasi-periodic processes in the associated structures. In this study, we developed a mathematical model for finite-lifetime and randomly occurring transients, and found that quasi-periodic processes with periods longer than the timescale of the transients, are detectable intrinsically in the form of trains. We simulate their propagation in an empirical solar atmospheric model with chromosphere, transition region, and corona. We found that, due to the filtering effect of the chromosphericmore » cavity, only the resonance period of the acoustic resonator is able to propagate to the upper atmosphere; such a scenario is applicable to slow magnetoacoustic waves in sunspots and active regions. If the thermal structure of the atmosphere is less wild and acoustic resonance does not take place, the long-period oscillations could propagate to the upper atmosphere. Such a case would be more likely to occur in polar plumes.« less

Climate and atmospheric modeling studies

NASA Technical Reports Server (NTRS)

1992-01-01

The climate and atmosphere modeling research programs have concentrated on the development of appropriate atmospheric and upper ocean models, and preliminary applications of these models. Principal models are a one-dimensional radiative-convective model, a three-dimensional global model, and an upper ocean model. Principal applications were the study of the impact of CO2, aerosols, and the solar 'constant' on climate.

Atmospheric helium and geomagnetic field reversals.

NASA Technical Reports Server (NTRS)

Sheldon, W. R.; Kern, J. W.

1972-01-01

The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

The upper atmosphere of Uranus

NASA Technical Reports Server (NTRS)

Strobel, Darrell F.; Yelle, Roger V.; Shemansky, Donald E.; Atreya, Sushil K.

1991-01-01

Voyager measurements of the upper atmosphere of Uranus are analyzed and developed. The upper atmosphere of Uranus is predominantly H2, with at most 10 percent He by volume, and the dominant constituent of the exosphere is H. The thermosphere is warm, with an asymptotic isothermal temperature of about 800 K. Atomic hydrogen at this temperature forms an extensive thermal corona and creates gas drag that severely limits the lifetime of small ring particles. The upper atmosphere emits copious amounts of UV radiation from pressures greater than 0.01 microbar. The depth of this emission level imposes a powerful constraint on permissible emission mechanisms. Electron excitation from a thin layer near the exobase appears to violate this constraint. Solar fluorescence is consistent with the observed trend in solar zenith-angle variation of the emissions and is absent from the night side of the planet. On Uranus, it accounts for the observed Lyman beta to H2 bands intensity ratio and an important fraction of the observed intensity (about 55 percent).

Limitation of Ground-based Estimates of Solar Irradiance Due to Atmospheric Variations

NASA Technical Reports Server (NTRS)

Wen, Guoyong; Cahalan, Robert F.; Holben, Brent N.

2003-01-01

The uncertainty in ground-based estimates of solar irradiance is quantitatively related to the temporal variability of the atmosphere's optical thickness. The upper and lower bounds of the accuracy of estimates using the Langley Plot technique are proportional to the standard deviation of aerosol optical thickness (approx. +/- 13 sigma(delta tau)). The estimates of spectral solar irradiance (SSI) in two Cimel sun photometer channels from the Mauna Loa site of AERONET are compared with satellite observations from SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on UARS (Upper Atmospheric Research Satellite) for almost two years of data. The true solar variations related to the 27-day solar rotation cycle observed from SOLSTICE are about 0.15% at the two sun photometer channels. The variability in ground-based estimates is statistically one order of magnitude larger. Even though about 30% of these estimates from all Level 2.0 Cimel data fall within the 0.4 to approx. 0.5% variation level, ground-based estimates are not able to capture the 27-day solar variation observed from SOLSTICE.

Ionization Efficiency in the Dayside Martian Upper Atmosphere

NASA Astrophysics Data System (ADS)

Cui, J.; Wu, X.-S.; Xu, S.-S.; Wang, X.-D.; Wellbrock, A.; Nordheim, T. A.; Cao, Y.-T.; Wang, W.-R.; Sun, W.-Q.; Wu, S.-Q.; Wei, Y.

2018-04-01

Combining the Mars Atmosphere and Volatile Evolution measurements of neutral atmospheric density, solar EUV/X-ray flux, and differential photoelectron intensity made during 240 nominal orbits, we calculate the ionization efficiency, defined as the ratio of the secondary (photoelectron impact) ionization rate to the primary (photon impact) ionization rate, in the dayside Martian upper atmosphere under a range of solar illumination conditions. Both the CO2 and O ionization efficiencies tend to be constant from 160 km up to 250 km, with respective median values of 0.19 ± 0.03 and 0.27 ± 0.04. These values are useful for fast calculation of the ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models. No substantial diurnal and solar cycle variations can be identified, except for a marginal trend of reduced ionization efficiency approaching the terminator. These observations are favorably interpreted by a simple scenario with ionization efficiencies, as a first approximation, determined by a comparison between relevant cross sections. Our analysis further reveals a connection between regions with strong crustal magnetic fields and regions with high ionization efficiencies, which are likely indicative of more efficient vertical transport of photoelectrons near magnetic anomalies.

Solar terrestrial observatory

NASA Technical Reports Server (NTRS)

1981-01-01

Eight basic solar-terrestrial scientific objectives that benefit from the Shuttle/Platform approach and a program of measurements for each are discussed. The objectives are to understand: (1) solar variability, (2) wave-particle processes, (3) magnetosphere-ionosphere mass transport, (4) the global electric circuit, (5) upper atmospheric dynamics, (6) middle atmospheric chemistry and energetics, (7) lower atmospheric turbidity, and (8) planetary atmospheric waves. A two stage approach to a multidisciplinary payload is developed: an initial STO, that uses a single platform in a low-Earth orbit, and an advanced STO that uses two platforms in differing orbits.

Planet-B: A Japanese Mars aeronomy observer

NASA Technical Reports Server (NTRS)

Tsuruda, K.

1992-01-01

An introduction is given to a Japanese Mars mission (Planet-B) which is being planned at the Institute of Space and Aeronautical Science (ISAS), Japan. Planet-B aims to study the upper atmosphere of Mars and its interaction with the solar wind. The launch of Planet-B is planned for 1996 on a new launcher, M-L, which is being developed at ISAS. In addition to the interaction with the solar wind, the structure of the Martian upper atmosphere is thought to be controlled by the meteorological condition in the lower atmosphere. The orbit of Planet-B was chosen so that it will pass two important regions, the region where the solar wind interacts with the Martian upper atmosphere and the tail region where ion acceleration is taking place. Considering the drag due to the Martian atmosphere, the periapsis altitude of 150 km and apoapsis of 10 Martian radii are planned. The orbit plane will be nearly parallel to the ecliptic plane. The altitude of the spacecraft will be spin stabilized and its spin axis will be controlled to the point of the earth. The dry weight of the spacecraft will be about 250 kg, including the scientific payload which consists of a magnetometer, plasma instruments, HF sounder, UV imaging spectrometer, and lower atmosphere monitor.

An analysis of Solar Mesospheric Explorer temperatures for the upper stratosphere and mesosphere

NASA Technical Reports Server (NTRS)

Clancy, R. Todd; Rusch, David W.

1993-01-01

We proposed to analyze Solar Mesosphere Explorer (SME) limb profiles of Rayleigh scattered solar flux at wavelengths of 304, 313, and 443 nm to retrieve atmospheric temperature profiles over the 40-65 km altitude region. These temperatures can be combined with the previous analysis of SME 296 nm limb radiances to construct a monthly average climatology of atmospheric temperatures over the 40-90 km, upper stratosphere-mesosphere region, with approximately 4 km vertical resolution. We proposed to investigate the detailed nature of the global temperature structure of this poorly measured region, based on these 1982-1986 SME temperatures. The average vertical structure of temperatures between the stratopause and mesopause has never been determined globally with vertical resolution sufficient to retrieve even scale-height structures. Hence, the SME temperatures provided a unique opportunity to study the detailed thermal structure of the mesosphere, in advance of Upper Atmosphere Research Satellite (UARS) measurements and the Thermosphere Ionosphere Mesosphere Energy and Dynamics (TIMED) mission.

Energy loss of solar p modes due to the excitation of magnetic sausage tube waves: Importance of coupling the upper atmosphere

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

Gascoyne, A.; Jain, R.; Hindman, B. W., E-mail: a.d.gascoyne@sheffield.ac.uk, E-mail: r.jain@sheffield.ac.uk

2014-07-10

We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation ofmore » Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = –z{sub 0}).« less

Energy Loss of Solar p Modes due to the Excitation of Magnetic Sausage Tube Waves: Importance of Coupling the Upper Atmosphere

NASA Astrophysics Data System (ADS)

Gascoyne, A.; Jain, R.; Hindman, B. W.

2014-07-01

We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = -z 0).

The solar-flare infrared continuum - Observational techniques and upper limits

NASA Technical Reports Server (NTRS)

Hudson, H. S.

1975-01-01

Exploratory observations at 20 microns and 350 microns have determined detection thresholds for solar flares in these wavelengths. In the 20-micron range, solar atmospheric fluctuations (the 'temperature field') set the basic limits on flare detectability at about 5 K; at 350 microns, extinction in the earth's atmosphere provides the basic limitation of about 30 K. These thresholds are low enough for the successful detection of several infrared-emitting components of large flares. The upper limits obtained for subflares indicate that the thickness of the H-alpha flare region does not exceed approximately 10 km. This result confirms the conclusion of Suemoto and Hiei (1959) regarding the small effective thickness of the H-alpha-emitting regions in solar flares.

The upper atmosphere and ionosphere of Mars

NASA Technical Reports Server (NTRS)

Brace, Larry H.

1992-01-01

The topics discussed include the following: the dynamic atmosphere of Mars; possible similarities with Earth and Venus; the atmosphere and ionosphere of Mars; solar wind interactions; future approved missions; and possible future mission.

Whole Atmosphere Simulation of Anthropogenic Climate Change

NASA Astrophysics Data System (ADS)

Solomon, Stanley C.; Liu, Han-Li; Marsh, Daniel R.; McInerney, Joseph M.; Qian, Liying; Vitt, Francis M.

2018-02-01

We simulated anthropogenic global change through the entire atmosphere, including the thermosphere and ionosphere, using the Whole Atmosphere Community Climate Model-eXtended. The basic result was that even as the lower atmosphere gradually warms, the upper atmosphere rapidly cools. The simulations employed constant low solar activity conditions, to remove the effects of variable solar and geomagnetic activity. Global mean annual mean temperature increased at a rate of +0.2 K/decade at the surface and +0.4 K/decade in the upper troposphere but decreased by about -1 K/decade in the stratosphere-mesosphere and -2.8 K/decade in the thermosphere. Near the mesopause, temperature decreases were small compared to the interannual variation, so trends in that region are uncertain. Results were similar to previous modeling confined to specific atmospheric levels and compared favorably with available measurements. These simulations demonstrate the ability of a single comprehensive numerical model to characterize global change throughout the atmosphere.

MAVEN Observations of Atmospheric Loss at Mars

NASA Astrophysics Data System (ADS)

Curry, Shannon; Luhmann, Janet; Jakosky, Bruce M.; Brain, David; LeBlanc, Francis; Modolo, Ronan; Halekas, Jasper S.; Schneider, Nicholas M.; Deighan, Justin; McFadden, James; Espley, Jared R.; Mitchell, David L.; Connerney, J. E. P.; Dong, Yaxue; Dong, Chuanfei; Ma, Yingjuan; Cohen, Ofer; Fränz, Markus; Holmström, Mats; Ramstad, Robin; Hara, Takuya; Lillis, Robert J.

2016-06-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been making observations of the Martian upper atmosphere and its escape to space since November 2014. The subject of atmospheric loss at terrestrial planets is a subject of intense interest not only because of the implications for past and present water reservoirs, but also for its impacts on the habitability of a planet. Atmospheric escape may have been especially effective at Mars, relative to Earth or Venus, due to its smaller size as well as the lack of a global dynamo magnetic field. Not only is the atmosphere less gravitationally bound, but also the lack of global magnetic field allows the impinging solar wind to interact directly with the Martian atmosphere. When the upper atmosphere is exposed to the solar wind, planetary neutrals can be ionized and 'picked up' by the solar wind and swept away.Both neutral and ion escape have played significant roles the long term climate change of Mars, and the MAVEN mission was designed to directly measure both escaping planetary neutrals and ions with high energy, mass, and time resolution. We will present 1.5 years of observations of atmospheric loss at Mars over a variety of solar and solar wind conditions, including extreme space weather events. We will report the average ion escape rate and the spatial distribution of escaping ions as measured by MAVEN and place them in context both with previous measurements of ion loss by other spacecraft (e.g. Phobos 2 and Mars Express) and with estimates of neutral escape rates by MAVEN. We will then report on the measured variability in ion escape rates with different drivers (e.g. solar EUV, solar wind pressure, etc.) and the implications for the total ion escape from Mars over time. Additionally, we will also discuss the implications for atmospheric escape at exoplanets, particularly weakly magnetized planetary bodies orbiting M-dwarfs, and the dominant escape mechanisms that may drive atmospheric erosion in other stellar systems.

The Solar-Terrestrial Environment

NASA Astrophysics Data System (ADS)

Hargreaves, John Keith

1995-05-01

The book begins with three introductory chapters that provide some basic physics and explain the principles of physical investigation. The principal material contained in the main part of the book covers the neutral and ionized upper atmosphere, the magnetosphere, and structures, dynamics, disturbances, and irregularities. The concluding chapter deals with technological applications. The account is introductory, at a level suitable for readers with a basic background in engineering or physics. The intent is to present basic concepts, and for that reason, the mathematical treatment is not complex. SI units are given throughout, with helpful notes on cgs units where these are likely to be encountered in the research literature. This book is suitable for advanced undergraduate and graduate students who are taking introductory courses on upper atmospheric, ionospheric, or magnetospheric physics. This is a successor to The Upper Atmosphere and Solar-Terrestrial Relations, published in 1979.

Low simulated radiation limit for runaway greenhouse climates

NASA Astrophysics Data System (ADS)

Goldblatt, Colin; Robinson, Tyler D.; Zahnle, Kevin J.; Crisp, David

2013-08-01

The atmospheres of terrestrial planets are expected to be in long-term radiation balance: an increase in the absorption of solar radiation warms the surface and troposphere, which leads to a matching increase in the emission of thermal radiation. Warming a wet planet such as Earth would make the atmosphere moist and optically thick such that only thermal radiation emitted from the upper troposphere can escape to space. Hence, for a hot moist atmosphere, there is an upper limit on the thermal emission that is unrelated to surface temperature. If the solar radiation absorbed exceeds this limit, the planet will heat uncontrollably and the entire ocean will evaporate--the so-called runaway greenhouse. Here we model the solar and thermal radiative transfer in incipient and complete runaway greenhouse atmospheres at line-by-line spectral resolution using a modern spectral database. We find a thermal radiation limit of 282Wm-2 (lower than previously reported) and that 294Wm-2 of solar radiation is absorbed (higher than previously reported). Therefore, a steam atmosphere induced by such a runaway greenhouse may be a stable state for a planet receiving a similar amount of solar radiation as Earth today. Avoiding a runaway greenhouse on Earth requires that the atmosphere is subsaturated with water, and that the albedo effect of clouds exceeds their greenhouse effect. A runaway greenhouse could in theory be triggered by increased greenhouse forcing, but anthropogenic emissions are probably insufficient.

Titan's Upper Atmosphere from Cassini/UVIS Solar Occultations

NASA Astrophysics Data System (ADS)

Capalbo, Fernando J.; Bénilan, Yves; Yelle, Roger V.; Koskinen, Tommi T.

2015-12-01

Titan’s atmosphere is composed mainly of molecular nitrogen, methane being the principal trace gas. From the analysis of 8 solar occultations measured by the Extreme Ultraviolet channel of the Ultraviolet Imaging Spectrograph (UVIS) on board Cassini, we derived vertical profiles of N2 in the range 1100-1600 km and vertical profiles of CH4 in the range 850-1300 km. The correction of instrument effects and observational effects applied to the data are described. We present CH4 mole fractions, and average temperatures for the upper atmosphere obtained from the N2 profiles. The occultations correspond to different times and locations, and an analysis of variability of density and temperature is presented. The temperatures were analyzed as a function of geographical and temporal variables, without finding a clear correlation with any of them, although a trend of decreasing temperature toward the north pole was observed. The globally averaged temperature obtained is (150 ± 1) K. We compared our results from solar occultations with those derived from other UVIS observations, as well as studies performed with other instruments. The observational data we present confirm the atmospheric variability previously observed, add new information to the global picture of Titan’s upper atmosphere composition, variability, and dynamics, and provide new constraints to photochemical models.

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.

The thermosphere and ionosphere of Venus

NASA Technical Reports Server (NTRS)

Cravens, T. E.

1992-01-01

Our knowledge of the upper atmosphere and ionosphere of Venus and its interaction with the solar wind has advanced dramatically over the last decade, largely due to the data obtained during the Pioneer Venus mission and to the theoretical work that was motivated by this data. Most of this information was obtained during the period 1978 through 1981, when the periapsis of the Pioneer Venus Orbiter (PVO) was still in the measurable atmosphere. However, solar gravitational perturbations will again lower the PVO periapsis into the upper atmosphere in September 1992, prior to the destruction of the spacecraft toward the end of this year. The physics and chemistry of the thermosphere and ionosphere of Venus are reviewed.

Panel Discussions on Total Solar Irradiance Variations and the Maunder Minimum

NASA Technical Reports Server (NTRS)

Pap, J. M.; White, O. R.

1993-01-01

For more than a decade, total solar irradiance has been monitored from several satellites, namely and Nimbus-7, Solar Maximum Mission (SMM), the NASA ERBS, NOAA9 and NOAA10,EURECA, and the Upper Atmospheric Research Satellite (SARS).

Model simulations of the impact of energetic particle precipitation onto the upper and middle atmosphere

NASA Astrophysics Data System (ADS)

Wieters, Nadine; Sinnhuber, Miriam; Winkler, Holger; Berger, Uwe; Maik Wissing, Jan; Stiller, Gabriele; Funke, Bernd; Notholt, Justus

Solar eruptions and geomagnetic storms can produce fluxes of high-energy protons and elec-trons, so-called Solar Energetic Particle Events, which can enter the Earth's atmosphere espe-cially in polar regions. These particle fluxes primarily cause ionisation and excitation in the upper atmosphere, and thereby the production of HOx and NOx species, which are catalysts for the reduction of ozone. To simulate such particle events, ionisation rates, calculated by the Atmospheric Ionization Module Osnabrück AIMOS (University of Osnabrück), have been implemented into the Bremen 3D Chemistry and Transport Model. To cover altitudes up to the mesopause, the model is driven by meteorological data, provided by the Leibniz-Institute Middle Atmosphere Model LIMA (IAP Kühlungsborn). For several electron and proton events during the highly solar-active period 2003/2004, model calculations have been carried out. To investigate the accordance of modeled to observed changes for atmospheric constituents like NO, NO2 , HNO3 , N2 O5 , ClO, and O3 , results of these calculations will be compared to measurements by the Michelson Interferometer for Passive Atmospheric Sounding MIPAS (ENVISAT) instrument. Computed model results and comparisons with measurements will be presented.

Condition of the upper atmosphere of the Earth at the final stage of flight manned orbital facility (MOF) "Mir". The modeling description

NASA Astrophysics Data System (ADS)

Boyarchuk, K. A.; Ivanov-Kholodny, G. S.; Kolomiitsev, O. P.; Surotkin, V. A.

At flooding MOF ``Mir'' the information on forecasting a condition of the upper atmosphere was used. The forecast was carried out on the basis of numerical model of an atmosphere, which was developed in IZMIRAN. This model allows reproducing and predicting a situation in an Earth space, in an atmosphere and an ionosphere, along an orbit of flight of a space vehicle in the various periods of solar-geophysical conditions. Thus preliminary forecasting solar and geomagnetic activity was carried out on the basis of an individual technique. Before the beginning of operation on flooding MOF ``Mir'' it was found out, that solar activity began to accrue catastrophically. The account of the forecast of its development has forced to speed up the moment of flooding to avoid dangerous development of events. It has allowed minimizing a risk factor - ``Mir'' was flooded successful in the commanded area of Pacific Ocean.

Realistic Modeling of Multi-Scale MHD Dynamics of the Solar Atmosphere

NASA Technical Reports Server (NTRS)

Kitiashvili, Irina; Mansour, Nagi N.; Wray, Alan; Couvidat, Sebastian; Yoon, Seokkwan; Kosovichev, Alexander

2014-01-01

Realistic 3D radiative MHD simulations open new perspectives for understanding the turbulent dynamics of the solar surface, its coupling to the atmosphere, and the physical mechanisms of generation and transport of non-thermal energy. Traditionally, plasma eruptions and wave phenomena in the solar atmosphere are modeled by prescribing artificial driving mechanisms using magnetic or gas pressure forces that might arise from magnetic field emergence or reconnection instabilities. In contrast, our 'ab initio' simulations provide a realistic description of solar dynamics naturally driven by solar energy flow. By simulating the upper convection zone and the solar atmosphere, we can investigate in detail the physical processes of turbulent magnetoconvection, generation and amplification of magnetic fields, excitation of MHD waves, and plasma eruptions. We present recent simulation results of the multi-scale dynamics of quiet-Sun regions, and energetic effects in the atmosphere and compare with observations. For the comparisons we calculate synthetic spectro-polarimetric data to model observational data of SDO, Hinode, and New Solar Telescope.

ScienceCast 53: The Surprising Power of a Solar Storm

NASA Image and Video Library

2012-03-22

A flurry of solar activity in early March dumped enough heat in Earth's upper atmosphere to power every residence in New York City for two years. The heat has since dissipated, but there's more to come as the solar cycle intensifies.

Modelling of plasma processes in cometary and planetary atmospheres

NASA Astrophysics Data System (ADS)

Campbell, L.; Brunger, M. J.

2013-02-01

Electrons from the Sun, often accelerated by magnetospheric processes, produce low-density plasmas in the upper atmospheres of planets and their satellites. The secondary electrons can produce further ionization, dissociation and excitation, leading to enhancement of chemical reactions and light emission. Similar processes are driven by photoelectrons produced by sunlight in upper atmospheres during daytime. Sunlight and solar electrons drive the same processes in the atmospheres of comets. Thus for both understanding of planetary atmospheres and in predicting emissions for comparison with remote observations it is necessary to simulate the processes that produce upper atmosphere plasmas. In this review, we describe relevant models and their applications and address the importance of electron-impact excitation cross sections, towards gaining a quantitative understanding of the phenomena in question.

European SpaceCraft for the study of Atmospheric Particle Escape (ESCAPE): a mission proposed in response to the ESA M5-call

NASA Astrophysics Data System (ADS)

Dandouras, Iannis; Yamauchi, Masatoshi; Rème, Henri; De Keyser, Johan; Marghitu, Octav; Fazakerley, Andrew; Grison, Benjamin; Kistler, Lynn; Milillo, Anna; Nakamura, Rumi; Paschalidis, Nikolaos; Paschalis, Antonis; Pinçon, Jean-Louis; Sakanoi, Takeshi; Wieser, Martin; Wurz, Peter; Yoshikawa, Ichiro; Häggström, Ingemar; Liemohn, Mike; Tian, Feng

2017-04-01

ESCAPE is a mission proposed in response to the ESA-M5 call that will quantitatively estimate the amount of escaping particles of the major atmospheric components (nitrogen and oxygen), as neutral and ionised species, escaping from the Earth as a magnetised planet. The spatial distribution and temporal variability of the flux of these species and their isotopic composition will be for the first time systematically investigated in an extended altitude range, from the exobase/upper ionosphere (500 km altitude) up to the magnetosphere. The goal is to understand the importance of each escape mechanism, its dependence on solar and geomagnetic activity, and to infer the history of the Earth's atmosphere over a long (geological scale) time period. Since the solar EUV and solar wind conditions during solar maximum at present are comparable to the solar minimum conditions 1-2 billion years ago, the escaping amount and the isotope and N/O ratios should be obtained as a function of external forcing (solar and geomagnetic conditions) to allow a scaling to the past. The result will be used as a reference to understand the atmospheric/ionospheric evolution of magnetised planets. To achieve this goal, a slowly spinning spacecraft is proposed equipped with a suite of instruments developed and supplied by an international consortium. These instruments will detect the upper atmosphere and magnetosphere escaping populations by a combination of in-situ measurements and of remote-sensing observations.

Response of the upper atmosphere to variations in the solar soft x-ray irradiance. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Bailey, Scott Martin

1995-01-01

Terrestrial far ultraviolet (FUV) airglow emissions have been suggested as a means for remote sensing the structure of the upper atmosphere. The energy which leads to the excitation of FUV airglow emissions is solar irradiance at extreme ultraviolet (EUV) and soft x-ray wavelengths. Solar irradiance at these wavelengths is known to be highly variable; studies of nitric oxide (NO) in the lower thermosphere have suggested a variability of more than an order of magnitude in the solar soft x-ray irradiance. To properly interpret the FUV airflow, the magnitude of the solar energy deposition must be known. Previous analyses have used the electron impact excited Lyman-Birge-Hopfield (LBH) bands of N2 to infer the flux of photoelectrons in the atmosphere and thus to infer the magnitude of the solar irradiance. This dissertation presents the first simultaneous measurements of the FUV airglow, the major atmospheric constituent densities, and the solar EUV and soft x-ray irradiances. The measurements were made on three flights of an identical sounding rocket payload at different levels of solar activity. The linear response in brightness of the LBH bands to variations in solar irradiance is demonstrated. In addition to the N2 LBH bands, atomic oxygen lines at 135.6 and 130.4 nm are also studied. Unlike the LBH bands, these emissions undergo radiative transfer effects in the atmosphere. The OI emission at 135.6 nm is found to be well modeled using a radiative transfer calculation and the known excitation processes. Unfortunately, the assumed processes leading to OI 130.4 nm excitation are found to be insufficient to reproduce the observed variability of this emission. Production of NO in the atmosphere is examined; it is shown that a lower than previously reported variability in the solar soft x-ray irradiance is required to explain the variability of NO.

The Earth's Middle Atmosphere: COSPAR Plenary Meeting, 29th, Washington, DC, 28 Aug.-5 Sep., 1992

NASA Technical Reports Server (NTRS)

Grosse, W. L. (Editor); Ghazi, A. (Editor); Geller, M. A. (Editor); Shepherd, G. G. (Editor)

1994-01-01

The conference presented the results from the Upper Atmosphere Research Satellite (UARS) in the areas of wind, temperature, composition, and energy input into the upper atmosphere. Also presented is the current status of validation of the UARS temperature and wind instruments measuring at and above the menopause. The two UARS instruments involved were the High Resolution Doppler Imager (HRDI) and the WIND Imaging Interferometer (WINDII). Papers are presented covering almost all aspects of middle atmospheric science, including dynamics, layering in the middle atmosphere, atmospheric composition, solar and geomagnetic effects, electrodynamics, and the ionosphere.

The statistical properties of vortex flows in the solar atmosphere

NASA Astrophysics Data System (ADS)

Wedemeyer, Sven; Kato, Yoshiaki; Steiner, Oskar

2015-08-01

Rotating magnetic field structures associated with vortex flows on the Sun, also known as “magnetic tornadoes”, may serve as waveguides for MHD waves and transport mass and energy upwards through the atmosphere. Magnetic tornadoes may therefore potentially contribute to the heating of the upper atmospheric layers in quiet Sun regions.Magnetic tornadoes are observed over a large range of spatial and temporal scales in different layers in quiet Sun regions. However, their statistical properties such as size, lifetime, and rotation speed are not well understood yet because observations of these small-scale events are technically challenging and limited by the spatial and temporal resolution of current instruments. Better statistics based on a combination of high-resolution observations and state-of-the-art numerical simulations is the key to a reliable estimate of the energy input in the lower layers and of the energy deposition in the upper layers. For this purpose, we have developed a fast and reliable tool for the determination and visualization of the flow field in (observed) image sequences. This technique, which combines local correlation tracking (LCT) and line integral convolution (LIC), facilitates the detection and study of dynamic events on small scales, such as propagating waves. Here, we present statistical properties of vortex flows in different layers of the solar atmosphere and try to give realistic estimates of the energy flux which is potentially available for heating of the upper solar atmosphere

TITAN’S UPPER ATMOSPHERE FROM CASSINI/UVIS SOLAR OCCULTATIONS

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

Capalbo, Fernando J.; Bénilan, Yves; Yelle, Roger V.

2015-12-01

Titan’s atmosphere is composed mainly of molecular nitrogen, methane being the principal trace gas. From the analysis of 8 solar occultations measured by the Extreme Ultraviolet channel of the Ultraviolet Imaging Spectrograph (UVIS) on board Cassini, we derived vertical profiles of N{sub 2} in the range 1100–1600 km and vertical profiles of CH{sub 4} in the range 850–1300 km. The correction of instrument effects and observational effects applied to the data are described. We present CH{sub 4} mole fractions, and average temperatures for the upper atmosphere obtained from the N{sub 2} profiles. The occultations correspond to different times and locations,more » and an analysis of variability of density and temperature is presented. The temperatures were analyzed as a function of geographical and temporal variables, without finding a clear correlation with any of them, although a trend of decreasing temperature toward the north pole was observed. The globally averaged temperature obtained is (150 ± 1) K. We compared our results from solar occultations with those derived from other UVIS observations, as well as studies performed with other instruments. The observational data we present confirm the atmospheric variability previously observed, add new information to the global picture of Titan’s upper atmosphere composition, variability, and dynamics, and provide new constraints to photochemical models.« less

Mesospheric Dynamical Changes Induced by the Solar Proton Events in October-November 2003

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Roble, Raymond G.; Fleming, Eric L.

2007-01-01

The very large solar storms in October-November 2003 caused solar proton events (SPEs) at the Earth that impacted the upper atmospheric polar cap regions. The Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM) was used to study the atmospheric dynamical influence of the solar protons that occurred in Oct-Nov 2003, the fourth largest period of SPEs measured in the past 40 years. The highly energetic solar protons caused ionization, as well as dissociation processes, and ultimately produced odd hydrogen (HOx) and odd nitrogen (NOy). Significant short-lived ozone decreases (10-70%) followed these enhancements of HOx and NOy and led to a cooling of most of the lower mesosphere. This cooling caused an atmospheric circulation change that led to adiabatic heating of the upper mesosphere. Temperature changes up to plus or minus 2.6 K were computed as well as wind (zonal, meridional, vertical) perturbations up to 20-25% of the background winds as a result of 22 the solar protons. The solar proton-induced mesospheric temperature and wind perturbations diminished over a period of 4-6 weeks after the SPEs. The Joule heating in the mesosphere, induced by the solar protons, was computed to be relatively insignificant for these solar storms with most of the temperature and circulation perturbations caused by ozone depletion in the sunlit hemisphere.

(?) The Air Force Geophysics Laboratory: Aeronomy, aerospace instrumentation, space physics, meteorology, terrestrial sciences and optical physics

NASA Astrophysics Data System (ADS)

McGinty, A. B.

1982-04-01

Contents: The Air Force Geophysics Laboratory; Aeronomy Division--Upper Atmosphere Composition, Middle Atmosphere Effects, Atmospheric UV Radiation, Satellite Accelerometer Density Measurement, Theoretical Density Studies, Chemical Transport Models, Turbulence and Forcing Functions, Atmospheric Ion Chemistry, Energy Budget Campaign, Kwajalein Reference Atmospheres, 1979, Satellite Studies of the Neutral Atmosphere, Satellite Studies of the Ionosphere, Aerospace Instrumentation Division--Sounding Rocket Program, Satellite Support, Rocket and Satellite Instrumentation; Space Physics Division--Solar Research, Solar Radio Research, Environmental Effects on Space Systems, Solar Proton Event Studies, Defense Meteorological Satellite Program, Ionospheric Effects Research, Spacecraft Charging Technology; Meteorology Division--Cloud Physics, Ground-Based Remote-Sensing Techniques, Mesoscale Observing and Forecasting, Design Climatology, Aircraft Icing Program, Atmospheric Dynamics; Terrestrial Sciences Division--Geodesy and Gravity, Geokinetics; Optical Physics Division--Atmospheric Transmission, Remote Sensing, INfrared Background; and Appendices.

Satellite Measurements of Middle Atmospheric Impacts by Solar Proton Events in Solar Cycle 23

NASA Technical Reports Server (NTRS)

Jackman, C.; Labow, G.; DeLand, M.; Fleming, E.; Sinnhuber, M.; Russell, J.

2005-01-01

Solar proton events (SPEs) are known to have caused changes in constituents in the Earth's neutral polar middle atmosphere in the most recent solar maximum period (solar cycle 23). The highly energetic protons produced ionizations, excitations, dissociations, and dissociative ionizations of the background constituents in the polar cap regions (greater than 60 degrees geomagnetic latitude), which led to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HOx increases led to short-lived ozone decreases in the polar mesosphere and upper stratosphere due to the short lifetimes of the HOx constituents. Polar middle mesospheric ozone decreases greater than 50% were observed and computed to last for hours to days due to the enhanced HOx. The NOy increases led to long-lived polar stratospheric ozone changes because of the long lifetime of the NOy family in this region. Upper stratospheric ozone decreases of greater than 10% were computed to last for several months past the solar events in the winter polar regions because of the enhanced NOy. Solar cycle 23 was especially replete with SPEs and huge fluxes of high energy protons occurred in July and November 2000, September and November 2001, April 2002, October 2003, and January 2005. Smaller, but still substantial, proton fluxes impacted the Earth during other months in this cycle. Observations by the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments along with GSFC 2D Model predictions will be shown in this talk.

Jupiter's outer atmosphere.

NASA Technical Reports Server (NTRS)

Brice, N. M.

1973-01-01

The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.

Pluto's Extended Atmosphere: New Horizons Alice Lyman-α Imaging

NASA Astrophysics Data System (ADS)

Retherford, Kurt D.; Gladstone, G. Randall; Stern, S. Alan; Weaver, Harold A.; Young, Leslie A.; Ennico, Kimberly A.; Olkin, Cathy B.; Cheng, Andy F.; Greathouse, Thomas K.; Hinson, David P.; Kammer, Joshua A.; Linscott, Ivan R.; Parker, Alex H.; Parker, Joel Wm.; Pryor, Wayne R.; Schindhelm, Eric; Singer, Kelsi N.; Steffl, Andrew J.; Strobel, Darrell F.; Summers, Michael E.; Tsang, Constantine C. C.; Tyler, G. Len; Versteeg, Maarten H.; Woods, William W.; Cunningham, Nathaniel J.; Curdt, Werner

2015-11-01

Pluto's upper atmosphere is expected to extend several planetary radii, proportionally more so than for any planet in our solar system. Atomic hydrogen is readily produced at lower altitudes due to photolysis of methane and transported upward to become an important constituent. The Interplanetary Medium (IPM) provides a natural light source with which to study Pluto's atomic hydrogen atmosphere. While direct solar Lyman-α emissions dominate the signal at 121.6 nm at classical solar system distances, the contribution of diffuse illumination by IPM Lyman-α sky-glow is roughly on par at Pluto (Gladstone et al., Icarus, 2015). Hydrogen atoms in Pluto's upper atmosphere scatter these bright Lyα emission lines, and detailed simulations of the radiative transfer for these photons indicate that Pluto would appear dark against the IPM Lyα background. The Pluto-Alice UV imaging spectrograph on New Horizons conducted several observations of Pluto during the encounter to search for airglow emissions, characterize its UV reflectance spectra, and to measure the radial distribution of IPM Lyα near the disk. Our early results suggest that these model predictions for the darkening of IPM Lyα with decreasing altitude being measureable by Pluto-Alice were correct. We'll report our progress toward extracting H and CH4 density profiles in Pluto's upper atmosphere through comparisons of these data with detailed radiative transfer modeling. These New Horizons findings will have important implications for determining the extent of Pluto's atmosphere and related constraints to high-altitude vertical temperature structure and atmospheric escape.This work was supported by NASA's New Horizons project.

Energy Deposition Processes in Titan's Upper Atmosphere

NASA Technical Reports Server (NTRS)

Sittler, Edward C., Jr.; Bertucci, Cesar; Coates, Andrew; Cravens, Tom; Dandouras, Iannis; Shemansky, Don

2008-01-01

Most of Titan's atmospheric organic and nitrogen chemistry, aerosol formation, and atmospheric loss are driven from external energy sources such as Solar UV, Saturn's magnetosphere, solar wind and galactic cosmic rays. The Solar UV tends to dominate the energy input at lower altitudes of approximately 1100 km but which can extend down to approximately 400 km, while the plasma interaction from Saturn's magnetosphere, Saturn's magnetosheath or solar wind are more important at higher altitudes of approximately 1400 km, but the heavy ion plasma [O(+)] of approximately 2 keV and energetic ions [H(+)] of approximately 30 keV or higher from Saturn's magnetosphere can penetrate below 950km. Cosmic rays with energies of greater than 1 GeV can penetrate much deeper into Titan's atmosphere with most of its energy deposited at approximately 100 km altitude. The haze layer tends to dominate between 100 km and 300 km. The induced magnetic field from Titan's interaction with the external plasma can be very complex and will tend to channel the flow of energy into Titan's upper atmosphere. Cassini observations combined with advanced hybrid simulations of the plasma interaction with Titan's upper atmosphere show significant changes in the character of the interaction with Saturn local time at Titan's orbit where the magnetosphere displays large and systematic changes with local time. The external solar wind can also drive sub-storms within the magnetosphere which can then modify the magnetospheric interaction with Titan. Another important parameter is solar zenith angle (SZA) with respect to the co-rotation direction of the magnetospheric flow. Titan's interaction can contribute to atmospheric loss via pickup ion loss, scavenging of Titan's ionospheric plasma, loss of ionospheric plasma down its induced magnetotail via an ionospheric wind, and non-thermal loss of the atmosphere via heating and sputtering induced by the bombardment of magnetospheric keV ions and electrons. This energy input evidently drives the large positive and negative ions observed below approximately 1100 km altitude with ion masses exceeding 10,000 daltons. We refer to these ions as seed particles for the aerosols observed below 300 km altitude. These seed particles can be formed, for example, from the polymerization of acetylene (C2H2) and benzene (C6H6) molecules in Titan's upper atmosphere to form polycyclic aromatic hydrocarbons (PAH) and/or fullerenes (C60). In the case of fullerenes, which are hollow spherical carbon shells, magnetospheric keV [O(+)] ions can become trapped inside the fullerenes and eventually find themselves inside the aerosols as free oxygen. The aerosols are then expected to fall to Titan's surface as polymerized hydrocarbons with trapped free oxygen where unknown surface chemistry can take place.

Effects of plasma drag on low Earth orbiting satellites due to solar forcing induced perturbations and heating

NASA Astrophysics Data System (ADS)

Nwankwo, Victor U. J.; Chakrabarti, Sandip K.; Weigel, Robert S.

2015-07-01

The upper atmosphere changes significantly in temperature, density and composition as a result of solar cycle variations, which causes severe storms and flares, and increases in the amount of absorbed solar radiation from solar energetic events. Satellite orbits are consequently affected by this process, especially those in low Earth orbit (LEO). In this paper, we present a model of atmospheric drag effects on the trajectory of two hypothetical LEO satellites of different ballistic coefficients, initially injected at h = 450 km. We investigate long-term trends of atmospheric drag on LEO satellites due to solar forcing induced atmospheric perturbations and heating at different phases of the solar cycle, and during short intervals of strong geomagnetic disturbances or magnetic storms. We show dependence of orbital decay on the severity of both solar cycle and phase and the extent of geomagnetic perturbations. The result of the model compares well with observed decay profile of some existing LEO satellites and provide a justification of the theoretical considerations used here.

The Influence of Solar Proton Events in Solar Cycle 23 on the Neutral Middle Atmosphere

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; vonKonig, Miriam; Anderson, John; Roble, Raymond G.; McPeters, Richard D.; Fleming, Eric L.; Russell, James M.

2004-01-01

Solar proton events (SPEs) can cause changes in constituents in the Earth's middle atmosphere. The highly energetic protons cause ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HO(x) (H, OH, HO2) and NO(y) (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HO(x) increases lead to short-lived ozone decreases in the mesosphere and upper stratosphere due to the short lifetimes of the HO, constituents. The NO(x) increases lead to long-lived stratospheric ozone changes because of the long lifetime of NO(y) constituents in this region. Solar cycle 23 was quite active with SPEs and very large fluxes of high energy protons occurred in July and November 2000, November 200 1, and April 2002. Smaller, but still substantial, proton fluxes impacted the Earth during other months in the 1997-2003 time period. The impact of the very large SPEs on the neutral middle atmosphere during solar cycle 23 will be discussed, including the HO(x), NO(y), ozone variations and induced atmospheric transport changes. Two multi-dimensional models, the Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model and the Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM), were used in computing the influence of the SPEs. The results of the GSFC 2D Model and the TIME-GCM will be shown along with comparisons to the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments.

The Physics and Diagnostic Potential of Ultraviolet Spectropolarimetry

NASA Astrophysics Data System (ADS)

Trujillo Bueno, Javier; Landi Degl'Innocenti, Egidio; Belluzzi, Luca

2017-09-01

The empirical investigation of the magnetic field in the outer solar atmosphere is a very important challenge in astrophysics. To this end, we need to identify, measure and interpret observable quantities sensitive to the magnetism of the upper chromosphere, transition region and corona. This paper provides an overview of the physics and diagnostic potential of spectropolarimetry in permitted spectral lines of the ultraviolet solar spectrum, such as the Mg ii h and k lines around 2800 Å, the hydrogen Lyman-α line at 1216 Å, and the Lyman-α line of He ii at 304 Å. The outer solar atmosphere is an optically pumped vapor and the linear polarization of such spectral lines is dominated by the atomic level polarization produced by the absorption and scattering of anisotropic radiation. Its modification by the action of the Hanle and Zeeman effects in the inhomogeneous and dynamic solar atmosphere needs to be carefully understood because it encodes the magnetic field information. The circular polarization induced by the Zeeman effect in some ultraviolet lines (e.g., Mg ii h & k) is also of diagnostic interest, especially for probing the outer solar atmosphere in plages and more active regions. The few (pioneering) observational attempts carried out so far to measure the ultraviolet spectral line polarization produced by optically pumped atoms in the upper chromosphere, transition region and corona are also discussed. We emphasize that ultraviolet spectropolarimetry is a key gateway to the outer atmosphere of the Sun and of other stars.

The New Horizons Ultraviolet Solar Occultation by Pluto's Atmosphere

NASA Astrophysics Data System (ADS)

Young, L. A.; Kammer, J.; Steffl, A.; Gladstone, R.; Summers, M. E.; Strobel, D. F.; Hinson, D. P.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.; McComas, D. J.

2017-12-01

The Alice instrument on NASA's New Horizons spacecraft observed an ultraviolet solar occultation by Pluto's atmosphere on 2015 July 14, as the spacecraft flew nearly diametrically though the solar shadow. The resulting dataset was a time-series of spectra from 52 to 187 nm with a spectral resolution of 0.3 nm. From these, we derived line-of-sight abundances and local number densities for the major species (N2 and CH4) and minor hydrocarbons (C2H2, C2H4, C2H6), and line-of-sight optical depth and extinction coefficients for the haze. Analysis of these data imply that (1) temperatures in Pluto's upper atmosphere were colder than expected before the New Horizons flyby, with upper atmospheric temperatures near 65-68 K, and subsequently lower escape rates, dominated by CH4 escape over N2; (2) the lower atmosphere was very stable, placing the homopause within 12 km of the surface, (3) the abundance profiles of the "C2Hx hydrocarbons" had non-exponential density profiles that compared favorably with models for hydrocarbon production near 300-400 km and haze condensation near 200 km, and (4) haze had an extinction coefficient approximately proportional to N2 density.

Multi-Satellite Measurements and Model Predictions of Mesospheric and Upper Stratospheric Influences from the Very Large July 14-16, 2000, Solar Proton Event

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; McPeters, Richard D.; Russell, James M.; Bevilacqua, Richard; Labow, Gordon J.; Fleming, Eric L.; Einaudi, Franco (Technical Monitor)

2000-01-01

A large solar flare with an associated coronal mass ejection occurred in mid-July and caused a very large solar proton event at the earth in the time period July 14-16, 2000. So far this is the largest solar storm of solar cycle 23. The solar proton fluxes were measured by instruments aboard the GOES-10 satellite and used in our proton energy deposition model to help quantify the energy input to the middle atmosphere during this large solar event. Using this computed energy deposition in the GSFC 2D atmospheric model resulted in a prediction of $>$ 20\\% increases in HO$-(x)$ (H, OH, HO$-(2)$) and $>$ 100\\% increases in NO$-(x)$ (N, NO, NO$-(2)$) constituents in the mesosphere and upper stratosphere at polar latitudes ($>$ 60 degrees geomagnetic). Both the HO$-(x)$ and NO$_fx)$ increases impacted ozone. Large atmospheric impacts have been measured with the NOAA 14 SBUV/2 instrument (0$_(3)$), the UARS HALOE instrument (NO, NO$-(2)$, 0$-(3)$), and the POAM III instrument (0$_{3}$, NO$-(2)$). Preliminary analysis indicates that measured (SBUV/2) and modelled 0$_{3}$ decreases from this solar event are generally in agreement in the Northern Hemisphere. Short-term ozone changes (during the event) indicate $\\sim$ 15% reduction at 2 hPa ($\\sim$ 45 km) up to $\\sim$ 40% reduction at 0.5 hPa ($\\sim$ 55 km). A longer-term ozone depletion of $\\sim$ 5% is indicated between 4 and 2 hPa ($\\sim$ 40-45 km). The middle atmospheric changes caused by this solar event were very large and occurred fairly quickly ($\\sim$ 1-2 days). Such a significant natural perturbation provides a good test of our understanding of the middle atmosphere. The measured and modelled impacts of this solar event will be compared and discussed in this paper.

Study of magnetic notions in the solar photosphere and their implications for heating the solar atmosphere

NASA Technical Reports Server (NTRS)

Noyes, Robert W.

1995-01-01

This progress report covers the first year of NASA Grant NAGw-2545, a study of magnetic structure in the solar photosphere and chromosphere. We have made significant progress in three areas: (1) analysis of vorticity in photospheric convection, which probably affects solar atmospheric heating through the stresses it imposes on photospheric magnetic fields; (2) modelling of the horizontal motions of magnetic footpoints in the solar photosphere using an assumed relation between brightness and vertical motion as well as continuity of flow; and (3) observations and analysis of infrared CO lines formed near the solar temperature minimum, whose structure and dynamics also yield important clues to the nature of heating of the upper atmosphere. Each of these areas are summarized in this report, with copies of those papers prepared or published this year included.

Neutral escape at Mars induced by the precipitation of high-energy protons and hydrogen atoms of the solar wind origin

NASA Astrophysics Data System (ADS)

Shematovich, Valery I.

2017-04-01

One of the first surprises of the NASA MAVEN mission was the observation by the SWIA instrument of a tenuous population of protons with solar wind energies travelling anti-sunward near periapsis, at altitudes of 150-250 km (Halekas et al., 2015). While the penetration of solar wind protons to low altitude is not completely unexpected given previous Mars Express results, this population maintains exactly the same velocity as the solar wind observed. From previous studies it was known that some fraction of the solar wind can interact with the extended corona of Mars. By charge exchange with the neutral particles in this corona, some fraction of the incoming solar wind protons can gain an electron and become an energetic neutral hydrogen atom. Once neutral, these particles penetrate through the Martian induced magnetosphere with ease, with free access to the collisional atmosphere/ionosphere. The origin, kinetics and transport of the suprathermal O atoms in the transition region (from thermosphere to exosphere) of the Martian upper atmosphere due to the precipitation of the high-energy protons and hydrogen atoms are discussed. Kinetic energy distribution functions of suprathermal and superthermal (ENA) oxygen atoms formed in the Martian upper atmosphere were calculated using the kinetic Monte Carlo model (Shematovich et al., 2011, Shematovich, 2013) of the high-energy proton and hydrogen atom precipitation into the atmosphere. These functions allowed us: (a) to estimate the non-thermal escape rates of neutral oxygen from the Martian upper atmosphere, and (b) to compare with available MAVEN measurements of oxygen corona. Induced by precipitation the escape of hot oxygen atoms may become dominant under conditions of extreme solar events - solar flares and coronal mass ejections, - as it was shown by recent observations of the NASA MAVEN spacecraft (Jakosky et al., 2015). This work is supported by the RFBR project and by the Basic Research Program of the Praesidium of the Russian Academy of Sciences (Program 1.7). References Shematovich, Solar System Res., 2013, v.47, 437. Shematovich et al., J. Geophys. Res., 2011, v.116, A11320. Halekas et al., Geophys. Res. Lett., 2015, v. 42. doi:10.1002/2015GL064781. Jakosky et al., Science, 2015, v. 350, Issue 6261, aad0210:1-7.

Cassini-VIMS at Jupiter: Solar occultation measurements using Io

USGS Publications Warehouse

Formisano, V.; D'Aversa, E.; Bellucci, G.; Baines, K.H.; Bibring, J.-P.; Brown, R.H.; Buratti, B.J.; Capaccioni, F.; Cerroni, P.; Clark, R.N.; Coradini, A.; Cruikshank, D.P.; Drossart, P.; Jaumann, R.; Langevin, Y.; Matson, D.L.; McCord, T.B.; Mennella, V.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, Christophe; Chamberlain, M.C.; Hansen, G.; Hibbits, K.; Showalter, M.; Filacchione, G.

2003-01-01

We report unusual and somewhat unexpected observations of the jovian satellite Io, showing strong methane absorption bands. These observations were made by the Cassini VIMS experiment during the Jupiter flyby of December/January 2000/2001. The explanation is straightforward: Entering or exiting from Jupiter's shadow during an eclipse, Io is illuminated by solar light which has transited the atmosphere of Jupiter. This light, therefore becomes imprinted with the spectral signature of Jupiter's upper atmosphere, which includes strong atmospheric methane absorption bands. Intercepting solar light refracted by the jovian atmosphere, Io essentially becomes a "miffor" for solar occultation events of Jupiter. The thickness of the layer where refracted solar light is observed is so large (more than 3000 km at Io's orbit), that we can foresee a nearly continuous multi-year period of similar events at Saturn, utilizing the large and bright ring system. During Cassini's 4-year nominal mission, this probing tecnique should reveal information of Saturn's atmosphere over a large range of southern latitudes and times. ?? 2003 Elsevier Inc. All rights reserved.

Interplanetary Coronal Mass Ejection effects on thermospheric density as inferred from International Space Station orbital data

NASA Astrophysics Data System (ADS)

Mendaza, T.; Blanco-Ávalos, J. J.; Martín-Torres, J.

2017-11-01

The solar activity induces long term and short term periodical variations in the dynamics and composition of Earth's atmosphere. The Sun also shows non periodical (i.e., impulsive) activity that reaches the planets orbiting around it. In particular, Interplanetary Coronal Mass Ejections (ICMEs) reach Earth and interact with its magnetosphere and upper neutral atmosphere. Nevertheless, the interaction with the upper atmosphere is not well characterized because of the absence of regular and dedicated in situ measurements at high altitudes; thus, current descriptions of the thermosphere are based on semi empirical models. In this paper, we present the total neutral mass densities of the thermosphere retrieved from the orbital data of the International Space Station (ISS) using the General Perturbation Method, and we applied these densities to routinely compiled trajectories of the ISS in low Earth orbit (LEO). These data are explicitly independent of any atmospheric model. Our density values are consistent with atmospheric models, which demonstrates that our method is reliable for the inference of thermospheric density. We have inferred the thermospheric total neutral density response to impulsive solar activity forcing from 2001 to the end of 2006 and determined how solar events affect this response. Our results reveal that the ISS orbital parameters can be used to infer the thermospheric density and analyze solar effects on the thermosphere.

Defining the Space Atmosphere Interaction Region (SAIR)

NASA Astrophysics Data System (ADS)

Sojka, J. J.; David, M.; Schunk, R. W.

2016-12-01

Is there a unique region between space and a planet's atmosphere in which the majority of the interactions exist? Does the location of this region depend on the intensity of space weather events, i.e., solar flares or geomagnetic storms? Present day research has developed the term "Space Atmosphere Interactions Region" (SAIR) to express the idea that our understanding is least developed in regions of the upper atmosphere where incoming energy is transformed into some form of thermal energy of the local particle populations. During such processes, both the atmosphere and ionosphere are locally modified resulting in dynamics and modified chemistry that impacts a large part of the upper atmosphere and ionosphere. We consider energy sources from the lower atmosphere (waves), the Sun (flares), and magnetosphere (magnetic storms) and the locations of their energy transformation processes. From below, the atmospheric waves of different scales from gravity waves to planetary waves, while from above solar irradiance, auroral precipitation, and Joule heating are discussed as they determine the SAIR location. Of specific emphasis will be the dependence, or not, of the SAIR on the solar flare or geomagnetic storm intensity. This region will be identified as the location where local energy deposition equals or exceeds local thermal energy of the atmospheric constituents. This energy deposition impacts the atmosphere, ionosphere, and magnetosphere. Its impacts extend well beyond the SAIR. The relevance of the SAIR concept to other planets, and hence, exoplanet will be point out.

A quasi-static model of global atmospheric electricity. II - Electrical coupling between the upper and lower atmosphere

NASA Technical Reports Server (NTRS)

Roble, R. G.; Hays, P. B.

1979-01-01

The paper presents a model of global atmospheric electricity used to examine the effect of upper atmospheric generators on the global electrical circuit. The model represents thunderstorms as dipole current generators randomly distributed in areas of known thunderstorm frequency; the electrical conductivity in the model increases with altitude, and electrical effects are coupled with a passive magnetosphere along geomagnetic field lines. The large horizontal-scale potential differences at ionospheric heights map downward into the lower atmosphere where the perturbations in the ground electric field are superimposed on the diurnal variation. Finally, changes in the upper atmospheric conductivity due to solar flares, polar cap absorptions, and Forbush decreases are shown to alter the downward mapping of the high-latitude potential pattern and the global distribution of fields and currents.

Computing the proton aurora at early Mars

NASA Astrophysics Data System (ADS)

Lovato, K.; Gronoff, G.; Curry, S.; Simon Wedlund, C.; Moore, W. B.

2017-12-01

In the early Solar System, ( 4 Gyr ago) our Sun was 70% less luminous than what is seen today but much more active. Indeed, for young stars, solar flares occurs more frequently and therefore so do coronal mass ejections and solar energetic particle events. With an increase in solar events, the flux of protons becomes extremely high, and affects planetary atmosphere in a more extreme way as today. Proton precipitation on planets has an impact on the energy balance of their upper atmospheres, can affect the photochemistry and create auroral emissions. Understanding the protons precipitation at the early Mars can help in understanding occurring chemical process as well as atmospheric evolution and escape. We concentrated our effort on the proton up to a MeV since they have the most important influence on the upper atmosphere. Using scaling laws, we estimated the proton flux for the Early Mars up to a MeV. A kinetic 1D code, validated for the current Mars, was used to compute the effects of the low energy protons precipitation on the Early Mars. This model solves the coupled H+/H multi-stream dissipative transport equation as well as the transport of the secondary electron. For the Early Mars, it allowed to compute the magnitude of the proton Aurora, as well as the corresponding upwards H flux.

Simulation of the August 21, 2017 Solar Eclipse Using the Whole Atmosphere Community Climate Model - eXtended (WACCM-X)

NASA Astrophysics Data System (ADS)

McInerney, J. M.; Liu, H.; Marsh, D. R.; Solomon, S. C.; Vitt, F.; Conley, A. J.

2017-12-01

The total solar eclipse of August 21, 2017 transited the entire continental United States. This presented an opportunity for model simulation of eclipse effects on the lower atmosphere, upper atmosphere, and ionosphere. The Community Earth System Model (CESM), v2.0, now includes a functional version of the Whole Atmosphere Community Climate Model - eXtended (WACCM-X) that has a fully interactive ionosphere and thermosphere. WACCM-X, with a model top up to 700 kilometers, is an atmospheric component of CESM and is being developed at the National Center for Atmospheric Research in Boulder, Colorado. Here we present results from simulations using this model during a total solar eclipse. This not only gives insights into the effects of the eclipse through the entire atmosphere from the surface through the ionosphere/thermosphere, but also serves as a validation tool for the model.

The Upper Atmosphere Research Satellite In-Flight Dynamics

NASA Technical Reports Server (NTRS)

Woodard, Stanley E.

1997-01-01

Upper Atmosphere Research Satellite flight data from the first 737 days after launch (September 1991) was used to investigate spacecraft disturbances and responses. The investigation included two in-flight dynamics experiments (approximately three orbits each). Orbital and configuration influences on spacecraft dynamic response were also examined. Orbital influences were due to temperature variation from crossing the Earth's terminator and variation of the solar incident energy as the orbit precessed. During the terminator crossing, the rapid ambient temperature change caused the spacecraft's two flexible appendages to experience thermal elastic bending (thermal snap). The resulting response was dependent upon the orientation of the solar array and the solar incident energy. Orbital influences were also caused by on-board and environmental disturbances and spacecraft configuration changes resulting in dynamic responses which were repeated each orbit. Configuration influences were due to solar array rotation changing spacecraft modal properties. The investigation quantified the spacecraft dynamic response produced by the solar array and high gain antenna harmonic drive disturbances. The solar array's harmonic drive output resonated two solar array modes. Friction in the solar array gear drive provided sufficient energy dissipation which prevented the solar panels from resonating catastrophically; however, the solar array vibration amplitude was excessively large. The resulting vibration had a latitude-specific pattern.

Solar Physics at Evergreen: Solar Dynamo and Chromospheric MHD

NASA Astrophysics Data System (ADS)

Zita, E. J.; Maxwell, J.; Song, N.; Dikpati, M.

2006-12-01

We describe our five year old solar physics research program at The Evergreen State College. Famed for its cloudy skies, the Pacific Northwest is an ideal location for theoretical and remote solar physics research activities. Why does the Sun's magnetic field flip polarity every 11 years or so? How does this contribute to the magnetic storms Earth experiences when the Sun's field reverses? Why is the temperature in the Sun's upper atmosphere millions of degrees higher than the Sun's surface temperature? How do magnetic waves transport energy in the Sun’s chromosphere and the Earth’s atmosphere? How does solar variability affect climate change? Faculty and undergraduates investigate questions such as these in collaboration with the High Altitude Observatory (HAO) at the National Center for Atmospheric Research (NCAR) in Boulder. We will describe successful student research projects, logistics of remote computing, and our current physics investigations into (1) the solar dynamo and (2) chromospheric magnetohydrodynamics.

Cosmic Rays over the Upper Mid-West. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Rygg, T. A.

1972-01-01

Differential energy spectra of cosmic ray protons and helium nuclei in the 100 to 260 MeV/nucleon were measured on balloon flights in the upper midwestern (U.S.) area. Solar cycle variations of atmospheric secondary protons were also investigated.

First Retrieval of Thermospheric Carbon Monoxide From Mars Dayglow Observations

NASA Astrophysics Data System (ADS)

Evans, J. Scott; Stevens, Michael H.; Jain, Sonal; Deighan, Justin; Lumpe, Jerry; Schneider, Nicholas M.; Stewart, A. Ian; Crismani, Matteo; Stiepen, Arnaud; Chaffin, Michael S.; Mayyasi-Matta, Majd A.; McClintock, William E.; Holsclaw, Greg; Lefevre, Franck; Lo, Daniel; Clarke, John T.; Montmessin, Franck; Bougher, Stephen W.; Bell, Jared M.; Eparvier, Frank; Thiemann, Ed; Mahaffy, Paul R.; Benna, Mehdi; Elrod, Meredith K.; Jakosky, Bruce

2017-10-01

As a minor species in the Martian thermosphere, Carbon Monoxide (CO) is a tracer that can be used to constrain changing circulation patterns between the lower thermosphere and upper mesosphere of Mars. By linking CO density distributions to dynamical wind patterns, the structure and variability of the atmosphere will be better understood. Direct measurements of CO can therefore provide insight into the magnitude and pattern of winds and provide a metric for studying the response of the atmosphere to solar forcing. In addition, CO measurements can help solve outstanding photochemical modeling problems in explaining the abundance of CO at Mars. CO is directly observable by electron impact excitation and solar resonance fluorescence emissions in the far-ultraviolet (FUV). The retrieval of CO from solar fluorescence was first proposed over 40 years ago, but has been elusive at Mars due to significant spectral blending. However, by simulating the spectral shape of each contributing emission feature, electron impact excitation and solar fluorescence brightnesses can be extracted from the composite spectrum using a multiple linear regression approach. We use CO Fourth Positive Group (4PG) molecular band emission observed on the limb (130 - 200 km) by the Imaging Ultraviolet Spectrograph (IUVS) on NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft over both northern and southern hemispheres from October 2014 to December 2016. We present the first direct retrieval of CO densities by FUV remote sensing in the upper atmosphere of Mars. Atmospheric composition is inferred using the terrestrial Atmospheric Ultraviolet Radiance Integrated Code adapted to the Martian atmosphere. We investigate the sensitivity of CO density retrievals to variability in solar irradiance, solar longitude, and local time. We compare our results to predictions from the Mars Global Ionosphere-Thermosphere Model as well as in situ measurements by the Neutral Gas and Ion Mass Spectrometer on MAVEN and quantify any differences.

Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?

NASA Astrophysics Data System (ADS)

Prikryl, Paul; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Bruntz, Robert; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel; Pastirčák, Vladimír

2017-04-01

More than four decades have passed since a link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity was discovered (Wilcox et al., Science, 180, 185-186, 1973). The link has been later confirmed and various physical mechanisms proposed but apart from controversy, little attention has been drawn to these results. To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., Ann. Geophys., 27, 1-30, 2009; Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219-231, 2016) is corroborated for the southern hemisphere. A physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297-375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands (Prikryl et al., Ann. Geophys., 27, 31-57, 2009). It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.

Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

NASA Technical Reports Server (NTRS)

Williams, D. J.; Grubb, R. N.; Evans, D. S.; Sauer, H. H.

1975-01-01

Monitoring of earth's atmosphere was conducted for several years utilizing the ITOS series of low-altitude, polar-orbiting weather satellites. A space environment monitoring package was included in these satellites to perform measurements of a portion of earth's charged particle environment. The charged particle observations proposed for the low-altitude weather satellite TIROS N, are described which will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Such observations may be of use in future studies of the relationships between geomagnetic activity and atmospheric weather pattern developments. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance of distinguishing between solar and geomagnetic activity as possible causative sources. Such differentiation is necessary because of the widely different spatial and time scales involved in the atmospheric energy input resulting from these various sources of activity.

Solar cyclic behavior of trapped energetic electrons in Earth's inner radiation belt

NASA Astrophysics Data System (ADS)

Abel, Bob; Thorne, Richard M.

1994-10-01

Magnetic electron spectrometer data from six satellites (OV3-3, OV1-14, OGO 5, S3-2, S3-3, and CRRES) have been used to study long-term (1966-1991) behavior of trapped energetic electrons in the inner radiation belt. Comparison of the observed energy spectra at L equal to or greater than 1.35 for different phases of the solar cycle reveals a clear trend toward enhanced fluxes during periods of solar maximum for energies below a few hundred keV; we suggest that this is caused by an increase in the rate of inward radial diffusion from a source at higher L. In contrast, for L less than 1.30, where atmospheric collisions become increasingly important, the electron flux is reduced during solar maximum; we attribute this to the expected increase in upper atmospheric densities. The electron flux above 1 MeV exhibits a systematic decay beyond 1979 to values well below the current NASA AE-8 model. This indicates that the natural background of high-energy electrons has previously been overestimated due to the long lasting presence of electrons produced by nuclear detonations in the upper atmosphere in the late 1950s and early 1960s.

Solar cyclic behavior of trapped energetic electrons in Earth's inner radiation belt

NASA Technical Reports Server (NTRS)

Abel, Bob; Thorne, Richard M.

1994-01-01

Magnetic electron spectrometer data from six satellites (OV3-3, OV1-14, OGO 5, S3-2, S3-3, and CRRES) have been used to study long-term (1966-1991) behavior of trapped energetic electrons in the inner radiation belt. Comparison of the observed energy spectra at L equal to or greater than 1.35 for different phases of the solar cycle reveals a clear trend toward enhanced fluxes during periods of solar maximum for energies below a few hundred keV; we suggest that this is caused by an increase in the rate of inward radial diffusion from a source at higher L. In contrast, for L less than 1.30, where atmospheric collisions become increasingly important, the electron flux is reduced during solar maximum; we attribute this to the expected increase in upper atmospheric densities. The electron flux above 1 MeV exhibits a systematic decay beyond 1979 to values well below the current NASA AE-8 model. This indicates that the natural background of high-energy electrons has previously been overestimated due to the long lasting presence of electrons produced by nuclear detonations in the upper atmosphere in the late 1950s and early 1960s.

Chandra Observations of the Solar System

NASA Astrophysics Data System (ADS)

Lisse, Carey

2014-11-01

Many solar system objects are now known to emit X-rays due to charge-exchange between highly charged solar wind (SW) minor ions and neutrals in their extended atmospheres, including Earth, Venus, Mars, Jupiter, and the heliosphere, with total power outputs on the MW - GW scale. (Currently only upper limits exist for Saturn and Pluto.) Chandra observations of their morphology, spectra, and time dependence provide important information about the neutral atmosphere structure and the SW flux and charge state. Chandra observations of solar x-ray scattering from Earth, Venus, Mars, Jupiter, Saturn, and the Moon have also provided important clues for the scattering material and the solar radiation field at the body. We present here a 15 year summary of Chandra's solar system observations.

Performance analysis for the cryogenic etalon spectrometer on the Upper Atmospheric Research Satellite

NASA Technical Reports Server (NTRS)

Roche, A. E.; Forney, P. B.; Kumer, J. B.; Naes, L. G.; Nast, T. C.

1983-01-01

The Upper Atmospheric Research Satellite (UARS) program has the objective of providing an 18-month to 2-year platform for observations of the upper atmosphere, giving particular attention to the stratosphere, mesosphere, and lower thermosphere. The primary aims of the mission are related to the measurement of the solar energy input between 120 and 500 km, the acquisition of global maps of the vertical and horizontal distribution of a series of critical trace and minor species, and the investigation of the dynamics of the upper atmosphere. One of several instruments designed to perform neutral species measurements on board the satellite is the Cryogenic Limb Array Etalon Spectrometer (CLAES). The CLAES experiment is concerned with measurements of concentrations of species of interest to the ozone layer balance. Attention is given to the performance requirements of the instrument and the effects of these requirements on the cryogenic design.

Ionizing Electrons on the Martian Nightside: Structure and Variability

NASA Astrophysics Data System (ADS)

Lillis, Robert J.; Mitchell, David L.; Steckiewicz, Morgane; Brain, David; Xu, Shaosui; Weber, Tristan; Halekas, Jasper; Connerney, Jack; Espley, Jared; Benna, Mehdi; Elrod, Meredith; Thiemann, Edward; Eparvier, Frank

2018-05-01

The precipitation of suprathermal electrons is the dominant external source of energy deposition and ionization in the Martian nightside upper atmosphere and ionosphere. We investigate the spatial patterns and variability of ionizing electrons from 115 to 600 km altitude on the Martian nightside, using CO2 electron impact ionization frequency (EIIF) as our metric, examining more than 3 years of data collected in situ by the Mars Atmosphere and Volatile EvolutioN spacecraft. We characterize the behavior of EIIF with respect to altitude, solar zenith angle, solar wind pressure, and the geometry and strength of crustal magnetic fields. EIIF has a complex and correlated dependence on these factors, but we find that it generally increases with altitude and solar wind pressure, decreases with crustal magnetic field strength and does not depend detectably on solar zenith angle past 115°. The dependence is governed by (a) energy degradation and backscatter by collisions with atmospheric neutrals below 220 km and (b) magnetic field topology that permits or retards electron access to certain regions. This field topology is dynamic and varies with solar wind conditions, allowing greater electron access at higher altitudes where crustal fields are weaker and also for higher solar wind pressures, which result in stronger draped magnetic fields that push closed crustal magnetic field loops to lower altitudes. This multidimensional electron flux behavior can in the future be parameterized in an empirical model for use as input to global simulations of the nightside upper atmosphere, which currently do not account for this important source of energy.

Energy balance in Saturn's upper atmosphere: Joint Lyman-α airglow observations with HST and Cassini

NASA Astrophysics Data System (ADS)

Ben-Jaffel, L.; Baines, K. H.; Ballester, G.; Holberg, H. B.; Koskinen, T.; Moses, J. I.; West, R. A.; Yelle, R. V.

2017-12-01

We are conducting Hubble Space Telescope UV spectroscopy of Saturn's disk-reflected Lyman-α line (Ly-α) at the same time as Cassini airglow measurements. Saturn's Ly-α emission is composed of solar and interplanetary (IPH) Ly-α photons scattered by its upper atmosphere. The H I Ly-a line probes different upper atmospheric layers down to the homopause, providing an independent way to investigate the H I abundance and energy balance. However, this is a degenerate, multi-parameter, radiative-transfer problem that depends on: H I column density, scattering process by thermal and superthermal hydrogen, time-variable solar and IPH sources, and instrument calibration. Our joint HST-Cassini campaign should break the degeneracy in the Saturn airglow problem. First, line integrated fluxes simultaneously measured by HST/STIS (dayside) and Cassini/UVIS (nightside), avoiding solar variability, should resolve the solar and IPH sources. Second, high-resolution spectroscopy with STIS will reveal superthermal line broadening not accessible with a low-resolution spectrometer like UVIS. Third, a second visit observing the same limb of Saturn will cross-calibrate the instruments and, with the STIS linewidth information, will yield the H I abundance, a key photochemical parameter not measured by Cassini. Finally, the STIS latitudinal mapping of the Ly-α linewidth will be correlated with Cassini's latitudinal temperature profile of the thermosphere, to provide an independent constraint on the thermospheric energy budget, a fundamental outstanding problem for giant planets. Here, we report the first results from the HST-Cassini campaign.

Heliophysics: Active Stars, their Astrospheres, and Impacts on Planetary Environments

NASA Astrophysics Data System (ADS)

Schrijver, C. J.; Bagenal, F.; Sojka, J. J.

2016-04-01

Preface; 1. Introduction Carolus J. Schrijver, Frances Bagenal and Jan J. Sojka; 2. Solar explosive activity throughout the evolution of the Solar System Rachel Osten; 3. Astrospheres, stellar winds, and the interstellar medium Brian Wood and Jeffrey L. Linsky; 4. Effects of stellar eruptions throughout astrospheres Ofer Cohen; 5. Characteristics of planetary systems Debra Fischer and Ji Wang; 6. Planetary dynamos: updates and new frontiers Sabine Stanley; 7. Climates of terrestrial planets David Brain; 8. Upper atmospheres of the giant planets Luke Moore, Tom Stallard and Marina Garland; 9. Aeronomy of terrestrial upper atmospheres David E. Siskind and Stephen W. Bougher; 10. Moons, asteroids, and comets interacting with their surroundings Margaret G. Kivelson; 11. Dusty plasmas Mihály Horányi; 12. Energetic-particle environments in the Solar System Norbert Krupp; 13. Heliophysics with radio scintillation and occultation Mario M. Bisi; Appendix 1. Authors and editors; List of illustrations; List of tables; References; Index.

Solar variability, coupling between atmospheric layers and climate change.

PubMed

Arnold, Neil

2002-12-15

One of the enduring puzzles of atmospheric physics is the extent to which changes in the Sun can influence the behaviour of the climate system. While solar-flux changes tend to be relatively modest, a number of observations of atmospheric parameters indicates a disproportionately large response. Global-scale models of the coupled middle and upper atmosphere have provided new insights into some of the mechanisms that may be responsible for the amplification of the solar signal. In particular, modification of the transport of heat and chemicals such as ozone by waves during periods of solar activity has been shown to make an important contribution to the climate of the stratosphere and mesosphere. In this paper, a review of some of the recent advances in understanding the coupling between atmospheric layers and how this work relates to Sun-weather relations and climate change in the troposphere will be presented, along with a discussion of some of the challenges that remain.

Semiempirical photospheric models of a solar flare on May 28, 2012

NASA Astrophysics Data System (ADS)

Andriets, E. S.; Kondrashova, N. N.

2015-02-01

The variation of the photosphere physical state during the decay phase of SF/B6.8-class solar flare on May 28, 2012 in active region NOAA 11490 is studied. We used the data of the spectropolarimetric observations with the French-Italian solar telescope THEMIS (Tenerife, Spain). Semi-empirical model atmospheres are derived from the inversion with SIR (Stokes Inversion based on Response functions) code. The inversion was based on Stokes profiles of six photospheric lines. Each model atmosphere has a two-component structure: a magnetic flux tube and non-magnetic surroundings. The Harvard Smithsonian Reference Atmosphere (HSRA) has been adopted for the surroundings. The macroturbulent velocity and the filling factor were assumed to be constant with the depth. The optical depth dependences of the temperature, magnetic field strength, and line-of-sight velocity are obtained from inversion. According to the received model atmospheres, the parameters of the magnetic field and the thermodynamical parameters changed during the decay phase of the flare. The model atmospheres showed that the photosphere remained in a disturbed state during observations after the maximum of the flare. There are temporal changes in the temperature and the magnetic field strength optical depth dependences. The temperature enhancement in the upper photospheric layers is found in the flaring atmospheres relative to the quiet-Sun model. The downflows are found in the low and upper photosphere at the decay phase of the flare.

An investigation of solar wind effects on the evolution of the Martian atmosphere

NASA Technical Reports Server (NTRS)

Luhmann, Janet G.

1994-01-01

This investigation concentrated on the question of how atmosphere escape, related to both photochemistry and the Mars solar wind interaction, may have affected the evolution of Mars' atmosphere over time. The principal investigator and postdoctoral researcher adopted the premise that contemporary escape processes have dominated the losses to space over the past 3.5 billion years, but that the associated loss rates have been modified by solar evolution. A model was constructed for the contemporary escape scenario based on knowledge gained from both Venus in-situ measurements from Pioneer Venus Orbiter and Mars measurements from Phobos-2. Venus provided a valuable second example of a weakly magnetized planet having a similar solar wind interaction where we have more knowledge from observations. The model included photochemical losses from recombining ionospheric molecular ions, scavenging Martian upper atmosphere ('pickup') ions by the solar wind, and sputtering of the atmosphere by reentering pickup ions. The existence of the latter mechanism was realized during the course of the supported investigation, and is now thought by Jakosky and Pepin to explain some of the Martian noble gas isotope ratios.

Upper limits to the fractionation of isotopes due to atmospheric escape: Implications for potential 14N/15N in Pluto's atmosphere

NASA Astrophysics Data System (ADS)

Mandt, K.; Mousis, O.

2014-12-01

Formation and evolution of the solar system is studied in part using stable isotope ratios that are presumed to be primordial, or representative of conditions in the protosolar Nebula. Comets, meteorites and giant planet atmospheres provide measurements that can reasonably be presumed to represent primordial conditions while the terrestrial planets, Pluto and Saturn's moon Titan have atmospheres that have evolved over the history of the solar system. The stable isotope ratios measured in these atmospheres are, therefore, first a valuable tool for evaluating the history of atmospheric escape and once escape is constrained can provide indications of conditions of formation. D/H ratios in the atmosphere of Venus provide indications of the amount of water lost from Venus over the history of the solar system, while several isotope ratios in the atmosphere of Mars provide evidence for long-term erosion of the atmosphere. We have recently demonstrated that the nitrogen ratios, 14N/15N, in Titan's atmosphere cannot evolve significantly over the history of the solar system and that the primordial ratio for Titan must have been similar to the value recently measured for NH3 in comets. This implies that the building blocks for Titan formed in the protosolar nebula rather than in the warmer subnebula surrounding Saturn at the end of its formation. Our result strongly contrasts with works showing that 14N/15N in the atmosphere of Mars can easily fractionate from the terrestrial value to its current value due to escape processes within the lifetime of the solar system. The difference between how nitrogen fractionates in Mars and Titan's atmospheres presents a puzzle for the fractionation of isotopes in an atmosphere due to atmospheric escape. Here, we present a method aiming at determining an upper limit to the amount of fractionation allowed to occur due to escape, which is a function of the escape flux and the column density of the atmospheric constituent. Through this approach, we demonstrate that fractionation on Titan is more limited than on Mars. When applied to Pluto, we find that any potential measurement of 14N/15N in Pluto's atmosphere can constrain the type of escape occurring from Pluto's atmosphere and possibly the source of nitrogen for Pluto.

Observation of NO(x) Enhancement and Ozone Depletion in the Northern and Southern hemispheres after the October-November 2003 Solar Proton Events

NASA Technical Reports Server (NTRS)

Lopez-Puertas, M.; Funke, B.; Gil-Lopez, S.; vonClarmann, T.; Stiller, G. P.; Hoepfner, M.; Kellmann, S.; Fischer, H.; Jackman, C. H.

2005-01-01

The large solar storms in October-November 2003 produced enormous solar proton events (SPEs) where high energetic particles reached the Earth and penetrated into the middle atmosphere in the polar regions. At this time, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was observing the atmosphere in the 6-68 km altitude range. MIPAS observations of NO(x) (NO+NO2) and O3 of the period from 25 October to 14 November 2003 are the first global measurements of NO(x) species, covering both the summer (daylight) and winter (dark) polar regions during an SPE. Very large values of NO(x) in the upper stratosphere of 180 ppbv (parts per billion by volume) have been measured, and a large asymmetry in Northern and Southern polar cap NO(x) enhancements was found. Arctic mean polar cap (>60 deg) NO(x) enhancements of 20 to 70 ppbv between 40 to 60 km lasted for at least two weeks, while the Antarctic mean NO(x) enhancement was between 10 and 35 ppbv and was halved after two weeks. Ozone shows depletion signatures associated with both HO(x) (H+OH+HO2) and NO(x) enhancements but at different time scales. Arctic lower mesospheric (upper stratospheric) ozone is reduced by 50-70% (30-40%) for about two weeks The large solar storms in October-November 2003 produced after the SPEs. A smaller ozone depletion signal was observed in the Antarctic atmosphere. After the locally produced Arctic middle and upper stratospheric as well as mesospheric NO(x) enhancement, large amounts of NO(x) were observed until the end of December. These are explained by downward transport processes.

Pluto's Solar Occultation from New Horizons

NASA Astrophysics Data System (ADS)

Young, Leslie; Kammer, Joshua; Steffl, Andrew J.; Gladstone, Randy; Summers, Michael; Strobel, Darrell F.; Hinson, David P.; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine; Ennico, Kimberly; McComas, Dave; New Horizons Atmospheres Science Theme Team

2017-10-01

The Alice instrument on NASA’s New Horizons spacecraft observed an ultraviolet solar occultation by Pluto's atmosphere on 2015 July 14. We derived line-of-sight abundances and local number densities for the major species (N2 and CH4) and minor hydrocarbons (C2H2, C2H4, C2H6), and line-of-sight optical depth and extinction coefficients for the haze. Our major conclusions are that (1) we confirmed temperatures in Pluto’s upper atmosphere that were colder than expected before the New Horizons flyby, with upper atmospheric temperatures near 65-68 K, and subsequently lower escape rates, (2) the lower atmosphere was very stable, placing the homopause within 12 km of the surface, (3) the abundance profiles of the “C2Hx hydrocarbons” had non-exponential density profiles that compare favorably with models for hydrocarbon production near 300-400 km and haze condensation near 200 km, and (4) haze had an extinction coefficient approximately proportional to N2 density.This work was supported by NASA’s New Horizons project.

Solar Cycle Response and Long-Term Trends in the Mesospheric Metal Layers

NASA Technical Reports Server (NTRS)

Dawkins, E. C. M.; Plane, J. M. C.; Chipperfield, M.; Feng, W.; Marsh, D. R.; Hoffner, J.; Janches, D.

2016-01-01

The meteoric metal layers (Na, Fe, and K) which form as a result of the ablation of incoming meteors act as unique tracers for chemical and dynamical processes that occur within the upper mesosphere lower thermosphere region. In this work, we examine whether these metal layers are sensitive Fe indicators of decadal long-term changes within the upper atmosphere. Output from a whole-atmosphere climate model is used to assess the response of the Na, K, and Fe layers across a 50 year period (1955-2005). At short timescales, the K layer has previously been shown to exhibit a very different seasonal behavior compared to the other metals. Here we show that this unusual behavior is also exhibited at longer time scales (both the 11 year solar cycle and 50 year periods), where K displays a much more pronounced response to atmospheric temperature changes than either Na or Fe. The contrasting solar cycle behavior of the K and Na layers predicted by the model is confirmed using satellite and lidar observations for the period 2004-2013.

Improved Statistical Model Of 10.7-cm Solar Radiation

NASA Technical Reports Server (NTRS)

Vedder, John D.; Tabor, Jill L.

1993-01-01

Improved mathematical model simulates short-term fluctuations of flux of 10.7-cm-wavelength solar radiation during 91-day averaging period. Called "F10.7 flux", important as measure of solar activity and because it is highly correlated with ultraviolet radiation causing fluctuations in heating and density of upper atmosphere. F10.7 flux easily measureable at surface of Earth.

Spatial and temporal variations in infrared emissions of the upper atmosphere. 2. 15-μm carbon dioxide emission

NASA Astrophysics Data System (ADS)

Semenov, A. I.; Medvedeva, I. V.; Perminov, V. I.; Zheleznov, Yu. A.

2017-09-01

The results of rocket and satellite measurements of carbon dioxide emissions at a wavelength of 15 μm in the upper atmosphere have been systematized and analyzed. Analytical expressions describing the dependence of the altitude distribution of 15-μm CO2 emission intensity and its variation in the altitude range from 100 to 130 km on the season, latitude, and solar activity have been obtained.

Spacelab

NASA Image and Video Library

1994-11-04

This is an STS-66 mission onboard photo of the Space Shuttle Orbiter Atlantis showing the payload of the third Atmospheric Laboratory for Applications and Science (ATLAS-3) mission. During the ATLAS missions, international teams of scientists representing many disciplines combined their expertise to seek answers to complex questions about the atmospheric and solar conditions that sustain life on Earth. The ATLAS program specifically investigated how Earth's middle and upper atmospheres and climate are affected by by the sun and by products of industrial and agricultural activities on Earth. Thirteen ATLAS instruments supported experiments in atmospheric sciences, solar physics, space plasma physics, and astronomy. The instruments were mounted on two Spacelab pallets in the Space Shuttle payload bay. The ATLAS-3 mission continued a variety of atmospheric and solar studies to improve understanding of the Earth's atmosphere and its energy input from the sun. A key scientific objective was to refine existing data on variations in the fragile ozone layer of the atmosphere. The Orbiter Atlantis was launched on November 3, 1994 for the ATLAS-3 mission (STS-66).

Analysis of solar ultraviolet lines

NASA Technical Reports Server (NTRS)

Chipman, E.

1971-01-01

The formation of the strongest ultra-violet emission lines of Mg II, O I, C II, and C III in the solar atmosphere is studied in detail. The equations of statistical equilibrium and radiative transfer for each ion are solved using a general computer program that is capable of solving non-LTE line-formation problems for arbitrary atmospheric and atomic models. Interpreting the results in terms of the structure of the solar atmosphere, it is concluded that the HSRA atmosphere has a temperature too low by about 500 K near h = 1100 km and that a temperature plateau with T sub e approximately = 18,000 K and width close to 60 km exists in the upper chromosphere. The structure of the solar atmosphere in the range 20,000 to 100,000 K and the effects of microturbulence on the formation of lines are also investigated. Approximate analytic line-formation problems are solved, and more exact solutions are derived later. An attempt is made to make the best possible fit to the Ca II K line center-to-limb profiles with a one-component atmosphere, with an assumed source function and microturbulent velocity.

Investigation of the solar UV/EUV heating effect on the Jovian radiation belt by GMRT-IRTF observation

NASA Astrophysics Data System (ADS)

Kita, H.; Misawa, H.; Bhardwaj, A.; Tsuchiya, F.; Tao, C.; Uno, T.; Kondo, T.; Morioka, A.

2012-12-01

Jupiter's synchrotron radiation (JSR) is the emission from relativistic electrons, and it is the most effective probe for remote sensing of Jupiter's radiation belt from the Earth. Recent intensive observations of JSR revealed short term variations of JSR with the time scale of days to weeks. Brice and McDonough (1973) proposed a scenario for the short term variations; i.e, the solar UV/EUV heating for Jupiter's upper atmosphere causes enhancement of total flux density. The purpose of this study is to investigate whether sufficient solar UV/EUV heating in Jupiter's upper atmosphere can actually causes variation in the JSR total flux and brightness distribution. Previous JSR observations using the Giant Metrewave Radio Telescope (GMRT) suggested important characteristics of short term variations; relatively low energy particles are accelerated by some acceleration processes which might be driven by solar UV/EUV heating and/or Jupiter's own magnetic activities. In order to evaluate the effect of solar UV/EUV heating on JSR variations, we made coordinated observations using the GMRT and NASA Infra-Red Telescope Facility (IRTF). By using IRTF, we can estimate the temperature of Jupiter's upper atmosphere from spectroscopic observation of H_3^+ infrared emission. Hence, we can evaluate the relationship between variations in Jupiter's upper atmosphere initiated by the solar UV/EUV heating and its linkage with the JSR. The GMRT observations were made during Nov. 6-17, 2011 at the frequency of 235/610MHz. The H_3^+ 3.953 micron line was observed using the IRTF during Nov. 7-12, 2011. During the observation period, the solar UV/EUV flux variations expected on Jupiter showed monotonic increase. A preliminary analysis of GMRT 610MHz band showed a radio flux variation similar to that in the solar UV/EUV. Radio images showed that the emission intensity increased at the outer region and the position of equatorial peak emission moved in the outward direction. If radial diffusion increases globally by the solar UV/EUV heating, it is expected that the peak intensity would increase and the peak position move inwards. However, our results are not consistent with the global enhancement of radial diffusion. In addition to that, the equatorial H_3^+ emission indicated that emission intensity decreased from the first day of observation to the last day. It is expected that equatorial temperature of Jupiter's atmosphere decreases during this observation period. Therefore, we propose that radial diffusion increased not globally but only at the outer region around L=2-3 during this period. From this hypothesis, it is expected that enhancement of radial diffusion at the outer region is caused by high latitude temperature enhancement. We discuss possible causes of the short term variations of JSR from the IRTF observation results at high latitude.

The SOLAR-C Mission: Science Objectives and Current Status

NASA Astrophysics Data System (ADS)

Suematsu, Y.; Solar-C Working Group

2016-04-01

The SOLAR-C is a Japan-led international solar mission for mid-2020s designed to investigate the magnetic activities of the Sun, focusing on the study in heating and dynamical phenomena of the chromosphere and corona, and to advance algorithms for predicting short and long term solar magnetic activities. For these purposes, SOLAR-C will carry three dedicated instruments; the Solar UV-Vis-IR Telescope (SUVIT), the EUV Spectroscopic Telescope (EUVST) and the High Resolution Coronal Imager (HCI), to jointly observe the entire visible solar atmosphere with essentially the same high spatial resolution (0.1"-0.3"), performing high resolution spectroscopic measurements over all atmospheric regions and spectro-polarimetric measurements from the photosphere through the upper chromosphere. SOLAR-C will also contribute to understand the solar influence on the Sun-Earth environments with synergetic wide-field observations from ground-based and other space missions.

The Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution Mission

NASA Technical Reports Server (NTRS)

Mahaffy, Paul R.; Benna, Mehdi; King, Todd; Harpold, Daniel N.; Arvey, Robert; Barciniak, Michael; Bendt, Mirl; Carrigan, Daniel; Errigo, Therese; Holmes, Vincent;

Saturn/Titan Rendezvous: A Solar-Sail Aerocapture Mission

NASA Technical Reports Server (NTRS)

Matloff, Gregory L.; Taylor, Travis; Powell, Conley

2004-01-01

A low-mass Titan orbiter is proposed that uses conservative or optimistic solar sails for all post-Earth-escape propulsion. After accelerating the probe onto a trans-Saturn trajectory, the sail is used parachute style for Saturn capture during a pass through Saturn's outer atmosphere. If the apoapsis of the Saturn-capture orbit is appropriate, the aerocapture maneuver can later be repeated at Titan so that the spacecraft becomes a satellite of Titan. An isodensity-atmosphere model is applied to screen aerocapture trajectories. Huygens/Cassini should greatly reduce uncertainties regarding the upper atmospheres of Saturn and Titan.

A search for solar neutrons on a long duration balloon flight

NASA Technical Reports Server (NTRS)

Koga, R.; Frye, G. M., Jr.; Owens, A.; Denehy, B. V.; Mace, O.; Thomas, J.

1985-01-01

The EOSCOR 3 detector, designed to measure the flux of solar neutrons, was flown on a long duration RACOON balloon flight from Australia during Jan. through Feb, 1983. The Circum-global flight lasted 22 days. No major solar activity occurred during the flight and thus only an upper limit to the solar flare neutrons flux is given. The atmospheric neutron response is compared with that obtained on earlier flights from Palestine, Texas.

A search for solar neutrons on a long duration balloon flight

NASA Astrophysics Data System (ADS)

Koga, R.; Frye, G. M., Jr.; Owens, A.; Denehy, B. V.; Mace, O.; Thomas, J.

1985-08-01

The EOSCOR 3 detector, designed to measure the flux of solar neutrons, was flown on a long duration RACOON balloon flight from Australia during Jan. through Feb, 1983. The Circum-global flight lasted 22 days. No major solar activity occurred during the flight and thus only an upper limit to the solar flare neutrons flux is given. The atmospheric neutron response is compared with that obtained on earlier flights from Palestine, Texas.

Solar Effects on Global Climate Due to Cosmic Rays and Solar Energetic Particles

NASA Technical Reports Server (NTRS)

Turco, R. P.; Raeder, J.; DAuria, R.

2005-01-01

Although the work reported here does not directly connect solar variability with global climate change, this research establishes a plausible quantitative causative link between observed solar activity and apparently correlated variations in terrestrial climate parameters. Specifically, we have demonstrated that ion-mediated nucleation of atmospheric particles is a likely, and likely widespread, phenomenon that relates solar variability to changes in the microphysical properties of clouds. To investigate this relationship, we have constructed and applied a new model describing the formation and evolution of ionic clusters under a range of atmospheric conditions throughout the lower atmosphere. The activation of large ionic clusters into cloud nuclei is predicted to be favorable in the upper troposphere and mesosphere, and possibly in the lower stratosphere. The model developed under this grant needs to be extended to include additional cluster families, and should be incorporated into microphysical models to further test the cause-and-effect linkages that may ultimately explain key aspects of the connections between solar variability and climate.

Spatial and Temporal Variations of Infrared Emissions in the Upper Atmosphere. 3. 5.3-μm Nitric Oxide Emission

NASA Astrophysics Data System (ADS)

Semenov, A. I.; Medvedeva, I. V.; Perminov, V. I.

2018-03-01

The results of rocket and satellite measurements available in the literature of 5.3-μm nitric oxide emission in the upper atmosphere have been systematized and analyzed. Analytical dependences describing the height distribution of volumetric intensity of 5.3-μm emission of the NO molecule and its variations in a range of heights from 100 to 130 km as a function of the time of year, day, latitude, and solar activity have been obtained.

On ion escape from Venus

NASA Astrophysics Data System (ADS)

Jarvinen, R.

2011-04-01

This doctoral thesis is about the solar wind influence on the atmosphere of the planet Venus. A numerical plasma simulation model was developed for the interaction between Venus and the solar wind to study the erosion of charged particles from the Venus upper atmosphere. The developed model is a hybrid simulation where ions are treated as particles and electrons are modelled as a fluid. The simulation was used to study the solar wind induced ion escape from Venus as observed by the European Space Agency's Venus Express and NASA's Pioneer Venus Orbiter spacecraft. Especially, observations made by the ASPERA-4 particle instrument onboard Venus Express were studied. The thesis consists of an introductory part and four peer-reviewed articles published in scientific journals. In the introduction Venus is presented as one of the terrestrial planets in the Solar System and the main findings of the work are discussed within the wider context of planetary physics.Venus is the closest neighbouring planet to the Earth and the most earthlike planet in its size and mass orbiting the Sun. Whereas the atmosphere of the Earth consists mainly of nitrogen and oxygen, Venus has a hot carbon dioxide atmosphere, which is dominated by the greenhouse effect. Venus has all of its water in the atmosphere, which is only a fraction of the Earth's total water supply. Since planets developed presumably in similar conditions in the young Solar System, why Venus and Earth became so different in many respects?One important feature of Venus is that the planet does not have an intrinsic magnetic field. This makes it possible for the solar wind, a continuous stream of charged particles from the Sun, to flow close to Venus and to pick up ions from the planet's upper atmosphere. The strong intrinsic magnetic field of the Earth dominates the terrestrial magnetosphere and deflects the solar wind flow far away from the atmosphere. The region around Venus where the planet's atmosphere interacts with the solar wind is called the plasma environment or the induced magnetosphere.Main findings of the work include new knowledge about the movement of escaping planetary ions in the Venusian induced magnetosphere. Further, the developed simulation model was used to study how the solar wind conditions affect the ion escape from Venus. Especially, the global three-dimensional structure of the Venusian particle and magnetic environment was studied. The results help to interpret spacecraft observations around the planet. Finally, several remaining questions were identified, which could potentially improve our knowledge of the Venus ion escape and guide the future development of planetary plasma simulations.

On ion escape from Venus

NASA Astrophysics Data System (ADS)

Jarvinen, Riku

2011-04-01

This doctoral thesis is about the solar wind influence on the atmosphere of the planet Venus. A numerical plasma simulation model was developed for the interaction between Venus and the solar wind to study the erosion of charged particles from the Venus upper atmosphere. The developed model is a hybrid simulation where ions are treated as particles and electrons are modelled as a fluid. The simulation was used to study the solar wind induced ion escape from Venus as observed by the European Space Agency's Venus Express and NASA's Pioneer Venus Orbiter spacecraft. Especially, observations made by the ASPERA-4 particle instrument onboard Venus Express were studied. The thesis consists of an introductory part and four peer-reviewed articles published in scientific journals. In the introduction Venus is presented as one of the terrestrial planets in the Solar System and the main findings of the work are discussed within the wider context of planetary physics. Venus is the closest neighbouring planet to the Earth and the most earthlike planet in its size and mass orbiting the Sun. Whereas the atmosphere of the Earth consists mainly of nitrogen and oxygen, Venus has a hot carbon dioxide atmosphere, which is dominated by the greenhouse effect. Venus has all of its water in the atmosphere, which is only a fraction of the Earth's total water supply. Since planets developed presumably in similar conditions in the young Solar System, why Venus and Earth became so different in many respects? One important feature of Venus is that the planet does not have an intrinsic magnetic field. This makes it possible for the solar wind, a continuous stream of charged particles from the Sun, to flow close to Venus and to pick up ions from the planet's upper atmosphere. The strong intrinsic magnetic field of the Earth dominates the terrestrial magnetosphere and deflects the solar wind flow far away from the atmosphere. The region around Venus where the planet's atmosphere interacts with the solar wind is called the plasma environment or the induced magnetosphere. Main findings of the work include new knowledge about the movement of escaping planetary ions in the Venusian induced magnetosphere. Further, the developed simulation model was used to study how the solar wind conditions affect the ion escape from Venus. Especially, the global three-dimensional structure of the Venusian particle and magnetic environment was studied. The results help to interpret spacecraft observations around the planet. Finally, several remaining questions were identified, which could potentially improve our knowledge of the Venus ion escape and guide the future development of planetary plasma simulations.

Monitoring of solar far ultraviolet radiation from the OSO-5 satellite

NASA Technical Reports Server (NTRS)

Rense, W. A.; Parker, R.

1972-01-01

A spectrophotometer for monitoring the solar EUV in three broad wavelength bands is described. The kind of data obtained, along with sources of error, are presented. The content of the tape library which contains the data is outlined. The scientific results are discussed. These include the following: solar flares in the EUV, solar eclipse observations in the EUV, SFD's and relationship to solar flares, and the application of satellite sunrise and sunset data for the study of model upper atmospheres for the earth.

Pluto's Ultraviolet Airglow and Detection of Ions in the Upper Atmosphere

NASA Astrophysics Data System (ADS)

Steffl, A.; Young, L. A.; Kammer, J.; Gladstone, R.; Hinson, D. P.; Summers, M. E.; Strobel, D. F.; Stern, S. A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.

2017-12-01

In July 2015, the Alice ultraviolet spectrograph aboard the New Horizons spacecraft made numerous observations of Pluto and its atmosphere. We present here the far ultraviolet reflectance spectrum of Pluto and airglow emissions from its atmosphere. At wavelengths greater than 1400Å, Pluto's spectrum is dominated by sunlight reflected from the surface of the planet. Various hydrocarbon species such as C2H4 are detected in absorption of the solar continuum. Below 1400Å, Pluto's atmosphere is opaque and the surface cannot be detected. However, after carefully removing various sources of background light, we see extremely faint airglow emissions (<0.05 Rayleighs/Ångstrom) from Pluto's atmosphere. All of the emissions are produced by nitrogen in various forms: molecular, atomic, and singly ionized. The detection of N+ at 1086Å is the first, and thus far only, direct detection of ions in Pluto's atmosphere. This N+ emission line is produced primarily by dissociative photoionization of molecular N2 by solar EUV photons (energy > 34.7 eV; wavelength < 360Å). Notably absent from Pluto's spectrum are emission lines from argon at 1048 and 1067Å. We place upper limits on the amount of argon in Pluto's atmosphere above the tau=1 level (observed to be at 750km tangent altitude) that are significantly lower than pre-encounter atmospheric models.

Prediction of three sigma maximum dispersed density for aerospace applications

NASA Technical Reports Server (NTRS)

Charles, Terri L.; Nitschke, Michael D.

1993-01-01

Free molecular heating (FMH) is caused by the transfer of energy during collisions between the upper atmosphere molecules and a space vehicle. The dispersed free molecular heating on a surface is an important constraint for space vehicle thermal analyses since it can be a significant source of heating. To reduce FMH to a spacecraft, the parking orbit is often designed to a higher altitude at the expense of payload capability. Dispersed FMH is a function of both space vehicle velocity and atmospheric density, however, the space vehicle velocity variations are insignificant when compared to the atmospheric density variations. The density of the upper atmosphere molecules is a function of altitude, but also varies with other environmental factors, such as solar activity, geomagnetic activity, location, and time. A method has been developed to predict three sigma maximum dispersed density for up to 15 years into the future. This method uses a state-of-the-art atmospheric density code, MSIS 86, along with 50 years of solar data, NASA and NOAA solar activity predictions for the next 15 years, and an Aerospace Corporation correlation to account for density code inaccuracies to generate dispersed maximum density ratios denoted as 'K-factors'. The calculated K-factors can be used on a mission unique basis to calculate dispersed density, and hence dispersed free molecular heating rates. These more accurate K-factors can allow lower parking orbit altitudes, resulting in increased payload capability.

Operational Data Reduction Procedure for Determining Density and Vertical Structure of the Martian Upper Atmosphere from Mars Global Surveyor Accelerometer Measurements

NASA Technical Reports Server (NTRS)

Cancro, George J.; Tolson, Robert H.; Keating, Gerald M.

1998-01-01

The success of aerobraking by the Mars Global Surveyor (MGS) spacecraft was partly due to the analysis of MGS accelerometer data. Accelerometer data was used to determine the effect of the atmosphere on each orbit, to characterize the nature of the atmosphere, and to predict the atmosphere for future orbits. To interpret the accelerometer data, a data reduction procedure was developed to produce density estimations utilizing inputs from the spacecraft, the Navigation Team, and pre-mission aerothermodynamic studies. This data reduction procedure was based on the calculation of aerodynamic forces from the accelerometer data by considering acceleration due to gravity gradient, solar pressure, angular motion of the MGS, instrument bias, thruster activity, and a vibration component due to the motion of the damaged solar array. Methods were developed to calculate all of the acceleration components including a 4 degree of freedom dynamics model used to gain a greater understanding of the damaged solar array. The total error inherent to the data reduction procedure was calculated as a function of altitude and density considering contributions from ephemeris errors, errors in force coefficient, and instrument errors due to bias and digitization. Comparing the results from this procedure to the data of other MGS Teams has demonstrated that this procedure can quickly and accurately describe the density and vertical structure of the Martian upper atmosphere.

From Anti-greenhouse Effect of Solar Absorbers to Cooling Effect of Greenhouse Gases: A 1-D Radiative Convective Model Study

NASA Astrophysics Data System (ADS)

Shia, R.

2012-12-01

The haze layer in Titan's upper atmosphere absorbs 90% of the solar radiation, but is inefficient for trapping infrared radiation generated by the surface. Its existence partially compensates for the greenhouse warming and keeps the surface approximately 9°C cooler than would otherwise be expected from the greenhouse effect alone. This is the so called anti-greenhouse effect (McKay et al., 1991). This effect can be used to alleviate the warming caused by the increasing level of greenhouse gases in the Earth's atmosphere. A one-dimensional radiative convective model (Kasting et al., 2009 and references listed there) is used to investigate the anti-greenhouse effect in the Earth atmosphere. Increasing of solar absorbers, e.g. aerosols and ozone, in the stratosphere reduces the surface solar flux and cool the surface. However, the absorption of the solar flux also increases the temperature in the upper atmosphere, while reduces the temperature at the surface. Thus, the temperature profile of the atmosphere changes and the regions with positive vertical temperature gradient are expanded. According to Shia (2010) the radiative forcing of greenhouse gases is directly related to the vertical temperature gradient. Under the new temperature profile increases of greenhouse gases should have less warming effect. When the solar absorbers keep increasing, eventually most of the atmosphere has positive temperature gradient and increasing greenhouse gases would cool the surface (Shia, 2011). The doubling CO2 scenario in the Earth atmosphere is simulated for different levels of solar absorbers using the 1-D RC model. The model results show that if the solar absorber increases to a certain level that less than 50% solar flux reaching the surface, doubling CO2 cools the surface by about 2 C. This means if the snowball Earth is generated by solar absorbers in the stratosphere, increasing greenhouse gases would make it freeze even more (Shia, 2011). References: Kasting, J. et al. 2009, http://vpl.astro.washington.edu/sci/AntiModels/models09.html McKay, C.P. et al. 1991, Titan: Greenhouse and Anti-greenhouse Effects on Titan. Science 253 (5024), 1118-21 Shia, R. 2011, Climate Effect of Greenhouse Gas: Warming or Cooling is Determined by Temperature Gradient, American Geophysical Union, Fall Meeting 2012, abstract #A51A-0274 Shia, R. 2010, Mechanism of Radiative Forcing of Greenhouse Gas and its Implication to the Global Warming, American Geophysical Union, Fall Meeting 2010, abstract #A11J-02

Spacelab

NASA Image and Video Library

1994-11-04

This is an STS-66 mission onboard photo showing the Remote Manipulator System (RMS) moving toward one of the solar science instruments for the third Atmospheric Laboratory for Applications and Science (ATLAS-3) mission in the cargo bay of the Orbiter Atlantis. During the ATLAS missions, international teams of scientists representing many disciplines combined their expertise to seek answers to complex questions about the atmospheric and solar conditions that sustain life on Earth. The ATLAS program specifically investigated how Earth's middle and upper atmospheres and climate are affected by by the sun and by products of industrial and agricultural activities on Earth. Thirteen ATLAS instruments supported experiments in atmospheric sciences, solar physics, space plasma physics, and astronomy. The instruments were mounted on two Spacelab pallets in the Space Shuttle payload bay. The ATLAS-3 mission continued a variety of atmospheric and solar studies, to improve understanding of the Earth's atmosphere and its energy input from the sun. A key scientific objective was to refine existing data on variations in the fragile ozone layer of the atmosphere. The Shuttle Orbiter Atlantis was launched on November 3, 1994 for the ATLAS-3 mission (STS-66). The ATLAS program was managed by the Marshall Space Flight Center.

Nitrogen Chemistry in Titan's Upper Atmosphere

NASA Technical Reports Server (NTRS)

McKay, Christopher P.; Cuzzi, Jeffrey (Technical Monitor)

1996-01-01

In Titan's upper atmosphere N2 is dissociated to N by solar UV and high energy electrons. This flux of N provides for interesting organic chemistry in the lower atmosphere of Titan. Previously the main pathway for the loss of this N was thought to be the formation of HCN, followed by diffusion of this HCN to lower altitudes leading ultimately to condensation. However, recent laboratory simulations of organic chemistry in Titan's atmosphere suggest that formation of the organic haze may be an important sink for atmospheric N. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere. This and other implications of this sink for the N balance on Titan are considered.

Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

NASA Technical Reports Server (NTRS)

Moon, S.; Simnett, G. M.; White, R. S.

1975-01-01

The UCR large area solid-angle double scatter neutron telescope was flown to search for solar neutrons on 3 balloon flights on September 26, 1971, May 14, 1972 and September 19, 1972. The first two flights were launched from Palestine, Texas and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet time solar neutron fluxes at the 95% confidence level are .00028, .00046, .00096 and .00090 neutrons/sq cm-sec in the energy intervals of 10-30, 30-50, 50-100 and 10-100 MeV, respectively.

Study of internal gravity waves in the meteor zone

NASA Technical Reports Server (NTRS)

Gavrilov, N. M.

1987-01-01

An important component of the dynamical regime of the atmosphere at heights near 100 km are internal gravity waves (IGW) with periods from about 5 min to about 17.5 hrs which propagate from the lower atmospheric layers and are generated in the uppermost region of the atmosphere. As IGW propagate upwards, their amplitudes increase and they have a considerable effect on upper atmospheric processes: (1) they provide heat flux divergences comparable with solar heating; (2) they influence the gaseous composition and produce wave variations of the concentrations of gaseous components and emissions of the upper atmosphere; and (3) they cause considerable acceleration of the mean stream. It was concluded that the periods, wavelengths, amplitudes and velocities of IGW propagation in the meteor zone are now measured quite reliably. However, for estimating the influence of IGW on the thermal regime and the circulation of the upper atmosphere these parameters are not as important as the values of wave fluxes of energy, heat, moment and mass.

Procedures for minimizing the effects of high solar activity on satellite tracking and ephemeris generation

NASA Technical Reports Server (NTRS)

Bredvik, Gordon D.

1990-01-01

We are currently experiencing a period of high solar radiation combined with wide short-term fluctuations in the radiation. The short-term fluctuations, especially when combined with highly energetic solar flares, can adversely affect the mission of U.S. Space Command's Space Surveillance Center (SSC) which catalogs and tracks the satellites in orbit around the Earth. Rapidly increasing levels of solar electromagnetic and/or particle radiation (solar wind) causes atmospheric warming, which, in turn, causes the upper-most portions of the atmosphere to expand outward, into the regime of low altitude satellites. The increased drag on satellites from this expansion can cause large, unmodeled, in-track displacements, thus undermining the SSC's ability to track and predict satellite position. On 13 March 1989, high solar radiation levels, combined with a high-energy solar flare, caused an exceptional amount of short-term atmospheric warming. The SSC temporarily lost track of over 1300 low altitude satellites--nearly half of the low altitude satellite population. Observational data on satellites that became lost during the days following the 13 March 'solar event' was analyzed and compared with the satellites' last element set prior to the event (referred to as a geomagnetic storm because of the large increase in magnetic flux in the upper atmosphere). The analysis led to a set of procedures for reducing the impact of future geomagnetic storms. These procedures adjust selected software limit parameters in the differential correction of element sets and in the observation association process and must be manually initiated at the onset of a geomagnetic storm. Sensor tasking procedures must be adjusted to ensure that a minimum of four observations per day are received for low altitude satellites. These procedures have been implemented and, thus far, appear to be successful in minimizing the effect of subsequent geomagnetic storms on satellite tracking and ephemeris computation.

Investigating Alfvénic wave propagation in coronal open-field regions

PubMed Central

Morton, R. J.; Tomczyk, S.; Pinto, R.

2015-01-01

The physical mechanisms behind accelerating solar and stellar winds are a long-standing astrophysical mystery, although recent breakthroughs have come from models invoking the turbulent dissipation of Alfvén waves. The existence of Alfvén waves far from the Sun has been known since the 1970s, and recently the presence of ubiquitous Alfvénic waves throughout the solar atmosphere has been confirmed. However, the presence of atmospheric Alfvénic waves does not, alone, provide sufficient support for wave-based models; the existence of counter-propagating Alfvénic waves is crucial for the development of turbulence. Here, we demonstrate that counter-propagating Alfvénic waves exist in open coronal magnetic fields and reveal key observational insights into the details of their generation, reflection in the upper atmosphere and outward propagation into the solar wind. The results enhance our knowledge of Alfvénic wave propagation in the solar atmosphere, providing support and constraints for some of the recent Alfvén wave turbulence models. PMID:26213234

Bombs and Flares at the Surface and Lower Atmosphere of the Sun

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

Hansteen, V. H.; Pereira, T. M. D.; Carlsson, M.

A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the H α line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging Spectrograph have revealed another type of plasma “bombs” (UV bursts) with high temperatures of perhaps up to 8 × 10{sup 4} K within the cooler lower solar atmosphere. Realistic numerical modeling showing such events is needed to explain their nature. Here, we report on 3D radiative magnetohydrodynamic simulations of magnetic flux emergence in the solar atmosphere. We find that ubiquitous reconnection between emerging bipolar magnetic fieldsmore » can trigger EBs in the photosphere, UV bursts in the mid/low chromosphere and small (nano-/micro-) flares (10{sup 6} K) in the upper chromosphere. These results provide new insights into the emergence and build up of the coronal magnetic field and the dynamics and heating of the solar surface and lower atmosphere.« less

Variability of the Martian thermospheric temperatures during the last 7 Martian Years

NASA Astrophysics Data System (ADS)

Gonzalez-Galindo, Francisco; Lopez-Valverde, Miguel Angel; Millour, Ehouarn; Forget, François

2014-05-01

The temperatures and densities in the Martian upper atmosphere have a significant influence over the different processes producing atmospheric escape. A good knowledge of the thermosphere and its variability is thus necessary in order to better understand and quantify the atmospheric loss to space and the evolution of the planet. Different global models have been used to study the seasonal and interannual variability of the Martian thermosphere, usually considering three solar scenarios (solar minimum, solar medium and solar maximum conditions) to take into account the solar cycle variability. However, the variability of the solar activity within the simulated period of time is not usually considered in these models. We have improved the description of the UV solar flux included on the General Circulation Model for Mars developed at the Laboratoire de Météorologie Dynamique (LMD-MGCM) in order to include its observed day-to-day variability. We have used the model to simulate the thermospheric variability during Martian Years 24 to 30, using realistic UV solar fluxes and dust opacities. The model predicts and interannual variability of the temperatures in the upper thermosphere that ranges from about 50 K during the aphelion to up to 150 K during perihelion. The seasonal variability of temperatures due to the eccentricity of the Martian orbit is modified by the variability of the solar flux within a given Martian year. The solar rotation cycle produces temperature oscillations of up to 30 K. We have also studied the response of the modeled thermosphere to the global dust storms in Martian Year 25 and Martian Year 28. The atmospheric dynamics are significantly modified by the global dust storms, which induces significant changes in the thermospheric temperatures. The response of the model to the presence of both global dust storms is in good agreement with previous modeling results (Medvedev et al., Journal of Geophysical Research, 2013). As expected, the simulated ionosphere is also sensitive to the variability of the solar activity. Acknowledgemnt: Francisco González-Galindo is funded by a CSIC JAE-Doc contract financed by the European Social Fund

Lessons from our Own Solar System: Generation Mechanisms of Radio Emissions from Earth, Saturn and Jupiter and Atmospheric Loss from Magnetized versus non-magnetized planets

NASA Astrophysics Data System (ADS)

Brandt, Pontus

2017-05-01

The understanding of the engines and mechanisms behind kilometric and decametric radio emissions from the planets in our own solar system have taken great leaps with missions such as the NASA/Cassini, IMAGE and Galileo missions. The periodic Saturn Kilometric Radiation (SKR), the Auroral Kilometric Radiation (AKR) at Earth and the periodic decametric radio emissions from Jupiter all point to the same generation mechanisms: very large-scale explosive plasma heating events in the magnetotail of each of the planets. The character and periodicity of the associated radio emissions not only tells us about the presence of a magnetic field but also about the plasma content and size of the planetary magnetosphere, and the nature of the interaction with the solar wind.The presence of a planetary magnetic field, as could be established for exoplanets by the positive detection of low-frequency exoplanetary radio emissions, has been thought to shield a planet from atmospheric loss to space. However, recent data from Mars Express, MAVEN, and Venus Express, together with the wealth of terrestrial measurements of atmospheric escape to space has brought a surprising question in to light: Does a planetary magnetic field suppress or enhance atmospheric loss? While at the non-magnetized planets such as Mars and Venus, the solar wind has a more direct access to the ionized upper atmosphere, these planets do set up self shielding currents that do limit escape. Furthermore, it is not clear if Mars have lost the majority of its atmosphere by condensation in to surface and sub-surface frost, or through atmospheric escape. At Earth, the geomagnetic field sets up a relatively large cross section to the solar wind, that allows the induced solar-wind electric field to transfer substantial energy to the upper ionosphere and atmosphere resulting in substantial loss. It is therefore not clear how a planetary magnetic field correlates to the atmospheric loss, or if it does at all.In this presentation we will summarize the recent findings in these two areas and what that implies for our understanding of stellar-wind interactions with exoplanetary magnetized and non-magnetized systems, and its possible constraints on habitability.

An assessment of thermal, wind, and planetary wave changes in the middle and lower atmosphere due to 11-year UV flux variations

NASA Technical Reports Server (NTRS)

Callis, L. B.; Alpert, J. C.; Geller, M. A.

1985-01-01

Hines (1974) speculated that solar-induced modifications of the middle and upper atmosphere may alter the transmissivity of the stratosphere to upwardly propagating atmospheric waves. It was suggested that subsequent constructive or destructive interference may result in a change of phase or amplitude of these waves in the troposphere leading to weather or climate changes. The present investigation has the objective to bring together both radiative transfer and planetary wave studies in an effort to assess specifically whether Hines mechanism can be initiated by the solar ultraviolet flux variability assumed to be associated with the 11-year solar cycle. The obtained results suggest that the presently studied mechanism, which links solar-induced zonal wind changes in the stratosphere and mesosphere to planetary wave changes in the troposphere, is not strong enough to cause substantive changes in the troposphere.

3rd IAGA/ICMA Workshop on Vertical Coupling in the Atmosphere/Ionosphere System/ Abstract

DTIC Science & Technology

2007-01-10

energy and momentum from the lower atmosphere to the upper atmosphere and ionosphere and vice versa. The programme focussed on various aspects and...ICMA Workshop Vertical Coupling in the Atmosphere/Ionosphere System - 6 - The influence of global dependence of gravity wave energy in the troposphere...transport during the polar night of thermospheric odd nitrogen produced by lower- energy electron precipitation and solar extreme UV fluxes. However, at low

Hydrodynamical Modeling of Hydrogen Escape from Rocky Planets

NASA Astrophysics Data System (ADS)

Barringer, Daniel; Zugger, M.; Kasting, J.

2013-01-01

Hydrogen escape affects both the composition of primitive atmospheres of terrestrial planets and the planet’s state of oxidation. On Mars, hydrogen escape played a critical role in how long the planet remained in a warm wet state amenable to life. For both solar and extrasolar planets, hydrogen-rich atmospheres are better candidates for originating life by way of Miller-Urey-type prebiotic synthesis. However, calculating the rate of atmospheric hydrogen escape is difficult, for a number of reasons. First, the escape can be controlled either by diffusion through the homopause or by conditions in the upper atmosphere, whichever is slower. Second, both thermal and non-thermal escape mechanisms are typically important. Third, thermal escape itself can be subdivided into Jeans escape (thin upper atmosphere), and hydrodynamic escape, and hydrodynamic escape can be further subdivided into transonic escape and slower subsonic escape, depending on whether the exobase occurs above or below the sonic point. Additionally, the rate of escape for real terrestrial planet atmospheres, which are not 100% hydrogen, depends upon the concentration of infrared coolants, and upon heating and photochemistry driven largely by extreme ultraviolet (EUV) radiation. We have modified an existing 1-D model of hydrodynamic escape (F. Tian et al., JGR, 2008) to work in the high- hydrogen regime. Calculations are underway to determine hydrogen escape rates as a function of atmospheric H2 mixing ratio and the solar EUV flux. We will compare these rates with the estimated upper limit on the escape rate based on diffusion. Initial results for early Earth and Mars will later be extended to rocky exoplanets.

Solar modulation of atmospheric electrification through variation of the conductivity over thunderstorms

NASA Technical Reports Server (NTRS)

Markson, R.

1975-01-01

It is suggested that variations of the current in the global atmospheric electrical circuit can be produced through regulation of the resistance between the tops of thunderclouds and the ionosphere. Long- and short-term changes in the conductivity of this region occur due to changes in the ionization rate resulting from solar activity. Previous suggestions that the phenomena might be due to conductivity variations in the fair weather part of the world or an influx of space charge to the upper atmosphere are discussed and considered unlikely. It might be possible to test the proposed mechanism by measuring the temporal variation of the ionospheric potential during distributed solar periods. Another approach would be to measure simultaneously the variation in ionization rate and electric current over thunderstorms. Several ways in which changes in atmospheric electrification might influence other meteorological phenomena are mentioned.

Lunar tidal effects during the 2013 stratospheric sudden warming as simulated by the TIME-GCM

NASA Astrophysics Data System (ADS)

Maute, A. I.; Forbes, J. M.; Zhang, X.; Fejer, B. G.; Yudin, V. A.; Pedatella, N. M.

2015-12-01

Stratospheric Sudden Warmings (SSW) are associated with strong planetary wave activity in the winterpolar stratosphere which result in a very disturbed middle atmosphere. The changes in the middle atmospherealter the propagation conditions and the nonlinear interactions of waves and tides, and result in SSW signals in the upper atmosphere in e.g., neutral winds, electric fields, ionospheric currents and plasma distribution. The upper atmosphere changes can be significant at low-latitudes even during medium solar flux conditions. Observationsalso reveal a strong lunar signal during SSW periods in the low latitude vertical drifts and in ionospheric quantities. Forbes and Zhang [2012] demonstrated that during the 2009 SSW period the Pekeris resonance peak of the atmosphere was altered such that the M2 and N2 lunar tidal componentsgot amplified. This study focuses on the effect of the lunar tidal forcing on the thermosphere-ionosphere system during theJanuary 2013 SSW period. We employthe NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM)with a nudging scheme using the Whole-Atmosphere-Community-Climate-Model-Extended (WACCM-X)/Goddard Earth Observing System Model, Version 5 (GEOS5) results to simulate the effects of meteorological forcing on the upper atmosphere. Additionally lunar tidal forcingis included at the lower boundary of the model. To delineate the lunar tidal effects a base simulation without lunar forcingis employed. Interestingly, Jicamarca observations of that period reveal a suppression of the daytime vertical drift before and after the drift enhancement due the SSW. The simulation suggests that the modulation of the vertical driftmay be caused by the interplay of the migrating solar and lunar semidiurnal tide, and therefore can only be reproduced by the inclusion of both lunar and solar tidal forcings in the model. In this presentation the changes due to the lunar tidal forcing will be quantified, and compared to observations.

Alfven-wave dissipation: A support mechanism for quiescent prominences

NASA Technical Reports Server (NTRS)

Jensen, Eberhart

1986-01-01

High resolution filtergrams or spectrograms of the main body of quiescent prominences often show a very vivid dynamical picture that cannot be reconciled with static models. Even if large differences exist between individual prominences in this respect, at least parts of the prominence are usually found to be in a 'choppy', turbulent state. Evidence for systematic flows are found in local regions in the prominence and also in the transition zone in the surroundings. These two regions are probably decoupled magnetically. Alfven waves are generally believed to be responsible for the heating in the upper chromosphere and corona (Hollweg 1986). Since evidence for the presence of Alfven-waves has also been found in the solar wind field, it is highly probable that such waves are generated in the convection zone of the sun and propagated outwards in the solar atmosphere wherever a proper magnetic field is present to carry the waves. The most basic magnetic formations in the solar atmosphere are simple loops. They occur all over the solar surface and cover a large range of magnetic field strengths. Loops with the strongest magnetic fields are found in active regions. It is to be expected that the Alfven-wave flux which is channelled into the loops from below, could show considerable variation both with heliocentric latitude, with time and locally between neighbouring loops. What happens when a magnetic loop is exposed to the appropriate Alfven-wave flux required to heat the upper solar atmosphere is examined.

Spatial and temporal variations in infrared emissions of the upper atmosphere. 1. Atomic oxygen (λ 63 μm) emission

NASA Astrophysics Data System (ADS)

Semenov, A. I.; Medvedeva, I. V.; Perminov, V. I.; Khomich, V. Yu.

2016-09-01

Rocket and balloon measurement data on atomic-oxygen (λ 63 µm) emission in the upper atmosphere are presented. The data from the longest (1989-2003) period of measurements of the atomic-oxygen (λ 63 µm) emission intensity obtained by spectral instruments on sounding balloons at an altitude of 38 km at midlatitudes have been systematized and analyzed. Regularities in diurnal and seasonal variations in the intensity of this emission, as well as in its relation with solar activity, have been revealed.

Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and a Source of Titan's Aerosols?

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.; Ali, A.; Cooper, J. F.; Hartle, R. E.; Johnson, R. E.; Coates, A. J.; Young, D. T.

2009-01-01

Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with approx.2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from the surface to 1200 km altitudes. The energy sources are solar UV, solar X-rays, Saturn's magnetospheric ions and electrons, solar wind and shocked magnetosheath ions and electrons, galactic cosmic rays (CCR) and the ablation of incident meteoritic dust from Enceladus' E-ring and interplanetary medium. Here it is proposed that the heavy atmospheric ions detected in situ by Cassini for heights >950 km, are the likely seed particles for aerosols detected by the Huygens probe for altitudes <100km. These seed particles may be in the form of polycyclic aromatic hydrocarbons (PAH) containing both carbon and hydrogen atoms CnHx. There could also be hollow shells of carbon atoms, such as C60, called fullerenes which contain no hydrogen. The fullerenes may compose a significant fraction of the seed particles with PAHs contributing the rest. As shown by Cassini, the upper atmosphere is bombarded by magnetospheric plasma composed of protons, H(2+) and water group ions. The latter provide keV oxygen, hydroxyl and water ions to Titan's upper atmosphere and can become trapped within the fullerene molecules and ions. Pickup keV N(2+), N(+) and CH(4+) can also be implanted inside of fullerenes. Attachment of oxygen ions to PAH molecules is uncertain, but following thermalization O(+) can interact with abundant CH4 contributing to the CO and CO2 observed in Titan's atmosphere. If an exogenic keV O(+) ion is implanted into the haze particles, it could become free oxygen within those aerosols that eventually fall onto Titan's surface. The process of freeing oxygen within aerosols could be driven by cosmic ray interactions with aerosols at all heights. This process could drive pre-biotic chemistry within the descending aerosols. Cosmic ray interactions with grains at the surface, including water frost depositing on grains from cryovolcanism, would further add to abundance of trapped free oxygen. Pre-biotic chemistry could arise within surface microcosms of the composite organic-ice grains, in part driven by free oxygen in the presence of organics and any heat sources, thereby raising the astrobiological potential for microscopic equivalents of Darwin's "warm ponds" on Titan.

Upper limits to the quiet-time solar neutron flux from 10 to 100 MeV

NASA Technical Reports Server (NTRS)

Moon, S.; Simnett, G. M.; White, R. S.

1976-01-01

A large-area solid-angle double-scatter neutron telescope was flown to search for solar neutrons on three balloon flights in 1971 and 1972. The first two flights were launched from Palestine, Texas, and the third from Cape Girardeau, Missouri. The float altitude on each flight was at about 5 g/sq cm residual atmosphere. Neutrons from 10 to 100 MeV were measured. No solar flares occurred during the flights. Upper limits to the quiet-time solar neutron fluxes at the 95-per cent confidence level are 2.8, 4.6, 9.6, and 9.0 x 10 to the -4th power neutron/sq cm/sec in the energy intervals of 10-30, 30-50, 50-100, and 10-100 MeV, respectively.

The Sun's Impact on Climate

NASA Technical Reports Server (NTRS)

Cahalan, Robert

2002-01-01

We provide an overview of the impact of the Sun on the Earth atmosphere and climate system, focused on heating of Earth's atmosphere and oceans. We emphasize the importance of the spectral measurements of SIM and SOLSTICE- that we must know how solar variations are distributed over ultraviolet, visible, and infrared wavelengths, since these have separate characteristic influences on Earth's ozone layer, clouds, and upper layers of the oceans. Emphasis is also given to understanding both direct and indirect influences of the Sun on the Earth, which involve feedbacks between Earth's stratosphere, troposphere, and oceans, each with unique time scales, dynamics, chemistry, and biology, interacting non-linearly. Especially crucial is the role of all three phases of water on Earth, water vapor being the primary greenhouse gas in the atmosphere, the importance of trace gases such as CO2 arising from their absorption in the "water vapor window" at 800 - 1250/cm (12.5 to 8 microns). Melting of polar ice is one major response to the post-industrial global warming, enhanced due to "ice-albedo" feedback. Finally, water in liquid form has a major influence due to cloud albedo feedback, and also due to the oceans' absorption of solar radiation, particularly at visible wavelengths, through the visible "liquid water window" that allows penetration of visible light deep into the mixed layer, while nearby ultraviolet and infrared wavelengths do not penetrate past the upper centimeter ocean surface skin layer. A large fraction of solar energy absorbed by the oceans goes into the latent heat of evaporation. Thus the solar heating of the atmosphere-ocean system is strongly coupled through the water cycle of evaporation, cloud formation, precipitation, surface runoff and ice formation, to Earth's energy budget and climate, each different climate component responding to variations in different solar spectral bands, at ultraviolet, visible and infrared wavelengths.

Variation of the Solar Microwave Spectrum in the Last Half Century

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

Shimojo, Masumi; Saito, Masao; Iwai, Kazumasa

The total solar fluxes at 1, 2, 3.75, and 9.4 GHz were observed continuously from 1957 to 1994 at Toyokawa, Japan, and from 1994 until now at Nobeyama, Japan, with the current Nobeyama Radio Polarimeters. We examined the multi-frequency and long-term data sets, and found that not only the microwave solar flux but also its monthly standard deviation indicate the long-term variation of solar activity. Furthermore, we found that the microwave spectra at the solar minima of Cycles 20–24 agree with each other. These results show that the average atmospheric structure above the upper chromosphere in the quiet-Sun has notmore » varied for half a century, and suggest that the energy input for atmospheric heating from the sub-photosphere to the corona have not changed in the quiet-Sun despite significantly differing strengths of magnetic activity in the last five solar cycles.« less

Update of the ISTP Solar Maximum Mission: ISTP Project Scientist for Theory and Ground-Based Observations

NASA Technical Reports Server (NTRS)

Curtis, Steve

1999-01-01

Building upon the numerous successes of the pre-solar maximum International Solar Terrestrial Physics (ISTP) mission, the ISTP Solar Maximum Mission is expected to produce new insights into global flow of energy, momentum, and mass, from the Sun, through the heliosphere, into the magnetosphere and to their final deposition in the terrestrial upper atmosphere/ionosphere system. Of particular interest is the determination of the geo-effectiveness of solar events, principally Coronal Mass Ejections (CMEs). Given the expected increased frequency and strength of CMEs during the Solar Maximum period, a major advance in our understanding of nature of the coupling of CMEs to the magnetosphere-ionosphere-atmosphere system is expected. The roles during this time of the various ISTP assets will be discussed. These assets will include the SOHO, Wind, Polar, and Geotail spacecraft, the ground-based observing networks and the theory tools.

The Influence of the Several Very Large Solar Proton Events in Years 2000-2003 on the Neutral Middle Atmosphere

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Sinnhuber, Miriam; Anderson, John; McPeters, Richard D.; FLeming, Eric L.; Russell, James M.

2004-01-01

Solar proton events (SPEs) are known to have caused changes in constituents in the Earth's neutral middle atmosphere. The highly energetic protons produce ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The HOx increases lead to short-lived ozone decreases in the mesosphere and upper stratosphere due to the short lifetimes of the HOx constituents. The NOy increases lead to long-lived stratospheric ozone changes because of the long lifetime of the NOy family in this region. The past four years, 2000-2003, have been replete with SPEs and huge fluxes of high energy protons occurred in July and November 2000, September and November 2001, April 2002, and October 2003. Smaller, but still substantial, proton fluxes impacted the Earth during other months from year 2000 to 2003. The Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model was used in computing the influence of the SPEs. The impact of these extremely large SPEs was calculated to be especially large in the upper stratosphere and mesosphere. The results of the GSFC 2D Model will be shown along with comparisons to the Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) and Solar Backscatter Ultraviolet 2 (SBUV/2) instruments.

SAMPEX Measurements of Geomagnetic-Cutoff Variations During the 4/21/02 Solar Energetic Particle Event

NASA Astrophysics Data System (ADS)

Labrador, A.; Leske, R.; Kanekal, S.; Klecker, B.; Looper, M.; Mazur, J.; Mewaldt, R.

2002-12-01

During large solar energetic particle (SEP) events the entry of solar and interplanetary energetic particles into the upper atmosphere is controlled by the geomagnetic cutoff. We define the cutoff latitude (Λ c) for a given rigidity particle to be effectively the minimum invariant latitude down to which particles can reach the upper atmosphere. The instruments on the polar-orbiting SAMPEX spacecraft have been used to measure geomagnetic cutoffs during a large sample of SEP events from solar cycle 23. During those events in which there is an associated geomagnetic storm, there are often large cutoff variations of as much as 5° to 10° in invariant latitude over the course of the event. This paper will combine measurements from the HILT, MAST, and PET instruments on SAMPEX to provide a comprehensive view of geomagnetic cutoff variations during the large SEP event of 4/21/02. We find that during the first two days of the event the cutoff latitude for ~30 MeV protons was at typical quiet-time levels. On April 23, following the arrival of a strong interplanetary shock, there was a sudden drop in the cutoff that lasted ~12 hours, with sizable local-time differences. During the next two days the cutoff steadily increased, giving a total variation of ~5° over the five days of the event. We combine these measurements of cutoff variations with measurements of the composition and energy spectra in the 4/21/02 event in order to estimate changes in the area of the polar caps over which particles of a given rigidity had access to the upper atmosphere.

SIMULATIONS OF ALFVÉN AND KINK WAVE DRIVING OF THE SOLAR CHROMOSPHERE: EFFICIENT HEATING AND SPICULE LAUNCHING

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

Brady, C. S.; Arber, T. D., E-mail: c.s.brady@warwick.ac.uk

2016-10-01

Two of the central problems in our understanding of the solar chromosphere are how the upper chromosphere is heated and what drives spicules. Estimates of the required chromospheric heating, based on radiative and conductive losses, suggest a rate of ∼0.1 erg cm{sup −3} s{sup −1} in the lower chromosphere and drops to ∼10{sup −3} erg cm{sup −3} s{sup −1} in the upper chromosphere. The chromosphere is also permeated by spicules, higher density plasma from the lower atmosphere propelled upwards at speeds of ∼10–20 km s{sup −1}, for so-called Type I spicules, which reach heights of ∼3000–5000 km above the photosphere.more » A clearer understanding of chromospheric dynamics, its heating, and the formation of spicules is thus of central importance to solar atmospheric science. For over 30 years it has been proposed that photospheric driving of MHD waves may be responsible for both heating and spicule formation. This paper presents results from a high-resolution MHD treatment of photospheric driven Alfvén and kink waves propagating upwards into an expanding flux tube embedded in a model chromospheric atmosphere. We show that the ponderomotive coupling from Alfvén and kink waves into slow modes generates shocks, which both heat the upper chromosphere and drive spicules. These simulations show that wave driving of the solar chromosphere can give a local heating rate that matches observations and drive spicules consistent with Type I observations all within a single coherent model.« less

The space shuttle payload planning working groups. Volume 5: Solar physics

NASA Technical Reports Server (NTRS)

1973-01-01

The findings of the Solar Physics working group of the space shuttle payload planning activity are presented. The areas to be investigated by the solar physics experiments are: (1) the production of mechanical energy in the subphotospheric layers and its transport and dissipation in the upper layers of the atmosphere, (2) the mass flux from the subphotospheric layers into the chromosphere and corona and beyond the solar wind, (3) solar activity and its relationship to magnetic fields, and (4) the production of solar flares. The approach to be followed in conducting the experiments and the equipment required are defined.

Dynamics of the Venus upper atmosphere: Outstanding problems and new constraints expected from Venus Express

NASA Astrophysics Data System (ADS)

Bougher, S. W.; Rafkin, S.; Drossart, P.

2006-11-01

A consistent picture of the dynamics of the Venus upper atmosphere from ˜90 to 200 km has begun to emerge [e.g., Bougher, S.W., Alexander, M.J., Mayr, H.G., 1997. Upper Atmosphere Dynamics: Global Circulation and Gravity Waves. Venus II, CH. 2.4. University of Arizona Press, Tucson, pp. 259-292; Lellouch, E., Clancy, T., Crisp, D., Kliore, A., Titov, D., Bougher, S.W., 1997. Monitoring of Mesospheric Structure and Dynamics. Venus II, CH. 3.1. University of Arizona Press, Tucson, pp. 295-324]. The large-scale circulation of the Venus upper atmosphere (upper mesosphere and thermosphere) can be decomposed into two distinct flow patterns: (1) a relatively stable subsolar-to-antisolar (SS-AS) circulation cell driven by solar heating, and (2) a highly variable retrograde superrotating zonal (RSZ) flow. Wave-like perturbations have also been observed. However, the processes responsible for maintaining (and driving variations in) these SS-AS and RSZ winds are not well understood. Variations in winds are thought to result from gravity wave breaking and subsequent momentum and energy deposition in the upper atmosphere [Alexander, M.J., 1992. A mechanism for the Venus thermospheric superrotation. Geophys. Res. Lett. 19, 2207-2210; Zhang, S., Bougher, S.W., Alexander, M.J., 1996. The impact of gravity waves on the Venus thermosphere and O2 IR nightglow. J. Geophys. Res. 101, 23195-23205]. However, existing data sets are limited in their spatial and temporal coverage, thereby restricting our understanding of these changing circulation patterns. One of the major goals of the Venus Express (VEX) mission is focused upon increasing our understanding of the circulation and dynamical processes of the Venus atmosphere up to the exobase [Titov, D.V., Lellouch, E., Taylor, F.W., 2001. Venus Express: Response to ESA's call for ideas for the re-use of the Mars Express platform. Proposal to European Space Agency, 1-74]. Several VEX instruments are slated to obtain remote measurements (2006-2008) that will complement those obtained earlier by the Pioneer Venus Orbiter (PVO) between 1978 and 1992. These VEX measurements will provide a more comprehensive investigation of the Venus upper atmosphere (90-200 km) structure and dynamics over another period in the solar cycle and for variable lower atmosphere conditions. An expanded climatology of Venus upper atmosphere structure and wind components will be developed. In addition, gravity wave parameters above the cloud tops will be measured (or inferred), and used to constrain gravity wave breaking models. In this manner, the gravity wave breaking mechanism (thought to regulate highly variable RSZ winds) can be tested using Venus general circulation models (GCMs).

Fluorescence of molecular hydrogen excited by solar extreme-ultraviolet radiation

NASA Technical Reports Server (NTRS)

Feldman, P. D.; Fastie, W. G.

1973-01-01

During trans-earth coast, the Apollo 17 ultraviolet spectrometer was scheduled to make observations of the far ultraviolet background in selected regions of the sky. In the course of one of these observations, the spacecraft fuel cells were routinely purged of excess hydrogen and water vapor. The ultraviolet fluorescence spectrum of the purged molecular hydrogen excited by solar extreme ultraviolet radiation is interpreted by absorption of solar L-beta and L-gamma radiation in the nearly resonant (6, 0) and (11, 0) Lyman bands. The results are deemed significant for ultraviolet spectroscopic investigations of the atmospheres of the moon and planets since Lyman-band fluorescence provides an unambiguous means of identification of molecular hydrogen in upper atmospheres.

Solar-terrestrial influences on weather and climate; Proceedings of the Symposium, Ohio State University, Columbus, Ohio, August 24-28, 1978

NASA Technical Reports Server (NTRS)

Mccormac, B. M. (Editor); Seliga, T. A.

1979-01-01

The book contains most of the invited papers and contributions presented at the symposium/workshop on solar-terrestrial influences on weather and climate. Four main issues dominate the activities of the symposium: whether solar variability relationships to weather and climate is a fundamental scientific question to which answers may have important implications for long-term weather and climate prediction; the sun-weather relationships; other potential solar influences on weather including the 11-year sunspot cycle, the 27-day solar rotation, and special solar events such as flares and coronal holes; and the development of practical use of solar variability as a tool for weather and climatic forecasting, other than through empirical approaches. Attention is given to correlation topics; solar influences on global circulation and climate models; lower and upper atmospheric coupling, including electricity; planetary motions and other indirect factors; experimental approaches to sun-weather relationships; and the role of minor atmospheric constituents.

Venusian atmospheric and Magellan properties from attitude control data. M.S. Thesis

NASA Technical Reports Server (NTRS)

Croom, Christopher A.; Tolson, Robert H.

1994-01-01

Results are presented of the study of the Venusian atmosphere, Magellan aerodynamic moment coefficients, moments of inertia, and solar moment coefficients. This investigation is based upon the use of attitude control data in the form of reaction wheel speeds from the Magellan spacecraft. As the spacecraft enters the upper atmosphere of Venus, measurable torques are experienced due to aerodynamic effects. Solar and gravity gradient effects also cause additional torques throughout the orbit. In order to maintain an inertially fixed attitude, the control system counteracts these torques by changing the angular rates of three reaction wheels. Model reaction wheel speeds are compared to observed Magellan reaction wheel speeds through a differential correction procedure. This method determines aerodynamic, atmospheric, solar pressure, and mass moment of inertia parameters. Atmospheric measurements include both base densities and scale heights. Atmospheric base density results confirm natural variability as measured by the standard orbital decay method. Potential inconsistencies in free molecular aerodynamic moment coefficients are identified. Moments of inertia are determined with a precision better than 1 percent of the largest principal moment of inertia.

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).

OBSERVATIONS OF LOW ENERGY SOLAR COSMIC RAYS FROM THE FLARE OF AUGUST 22, 1958

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

Anderson, K.A.; Arnoldy, R.; Hoffman, R.

1959-10-31

Observations were made of protons at balloon altitudes in the energy range 100 to 300 Mev following a solar sequence of optical flare, r-f noise bursts, and long enduring noise storm. Other particles are shown to have low upper limits to their abundance. The flare particles continue to be observed for at least 2 days and arguments are given to show that their storage and emission takes place in the solar atmosphere. The differential energy spectrum is derived from ionization versus atmospheric depth data and is found to be E/sup -5/ dE. Observations by riometer and VHF scatter propagation pathsmore » over the polar regions indicate that solar acceleration of protons up to roughly 100 Mev energy is rather frequent. (auth)« less

Tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control

NASA Astrophysics Data System (ADS)

Prikryl, Paul; Bruntz, Robert; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel

2018-06-01

Occurrence of severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system is investigated. It is observed that significant snowfall, wind and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur within a few days after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., 2009, 2016) is corroborated for the southern hemisphere. Cases of severe weather events are examined in the context of the magnetosphere-ionosphere-atmosphere (MIA) coupling. Physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., 1990) reveal that propagating waves originating in the lower thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere and initiate convection to form cloud/precipitation bands. It is primarily the energy provided by release of latent heat that leads to intensification of storms. These results indicate that vertical coupling in the atmosphere exerts downward control from solar wind to the lower atmospheric levels influencing tropospheric weather development.

Forecasting Space Weather Events for a Neighboring World

NASA Technical Reports Server (NTRS)

Zheng, Yihua; Mason, Tom; Wood, Erin L.

2015-01-01

Shortly after NASA's Mars Atmosphere and Volatile EvolutioN mission (MAVEN) spacecraft entered Mars' orbit on 21 September 2014, scientists glimpsed the Martian atmosphere's response to a front of solar energetic particles (SEPs) and an associated coronal mass ejection (CME). In response to some solar flares and CMEs, streams of SEPs burst from the solar atmosphere and are further accelerated in the interplanetary medium between the Sun and the planets. These particles deposit their energy and momentum into anything in their path, including the Martian atmosphere and MAVEN particle detectors. MAVEN scientists had been alerted to the likely CME-Mars encounter by a space weather prediction system that had its origins in space weather forecasting for Earth but now forecasts space weather for Earth's neighboring planets. The two Solar Terrestrial Relations Observatory spacecraft and Solar Heliospheric Observatory observed a CME on 26 September, with a trajectory that suggested a Mars intercept. A computer model developed for solar wind prediction, the Wang-Sheeley-Arge-Enlil cone model [e.g., Zheng et al., 2013; Parsons et al., 2011], running in real time at the Community Coordinated Modeling Center (CCMC) located at NASA Goddard since 2006, showed the CME propagating in the direction of Mars (Figure 1). According to MAVEN particle detectors, the disturbance and accompanying SEP enhancement at the leading edge of the CME reached Mars at approximately 17 hours Universal Time on 29 September 2014. Such SEPs may have a profound effect on atmospheric escape - they are believed to be a possible means for driving atmospheric loss. SEPs can cause loss of Mars' upper atmosphere through several loss mechanisms including sputtering of the atmosphere. Sputtering occurs when atoms are ejected from the atmosphere due to impacts with energetic particles.

Low Simulated Radiation Limit for Runaway Greenhouse Climates

NASA Technical Reports Server (NTRS)

Goldblatt, Colin; Robinson, Tyler D.; Zahnle, Kevin J.; Crisp, David

2013-01-01

Terrestrial planet atmospheres must be in long-term radiation balance, with solar radiation absorbed matched by thermal radiation emitted. For hot moist atmospheres, however, there is an upper limit on the thermal emission which is decoupled from the surface temperature. If net absorbed solar radiation exceeds this limit the planet will heat uncontrollably, the so-called \\runaway greenhouse". Here we show that a runaway greenhouse induced steam atmosphere may be a stable state for a planet with the same amount of incident solar radiation as Earth has today, contrary to previous results. We have calculated the clear-sky radiation limits at line-by-line spectral resolution for the first time. The thermal radiation limit is lower than previously reported (282 W/sq m rather than 310W/sq m) and much more solar radiation would be absorbed (294W/sq m rather than 222W/sq m). Avoiding a runaway greenhouse under the present solar constant requires that the atmosphere is subsaturated with water, and that cloud albedo forcing exceeds cloud greenhouse forcing. Greenhouse warming could in theory trigger a runaway greenhouse but palaeoclimate comparisons suggest that foreseeable increases in greenhouse gases will be insufficient to do this.

Change in the radiative output of the Sun in 1992 and its effect in the thermosphere

NASA Technical Reports Server (NTRS)

White, O. R.; Rottman, G. J.; Woods, T. N.; Knapp, B. G.; Keil, S. L.; Livingston, W. C.; Tapping, K. F.; Donnelly, R. F.; Puga, L. C.

1994-01-01

Ground and space measurements of the solar spectral irradiance at radio, visible, UV, and X ray wavelengths show a large decline in the first 6 months of 1992. This sustained drop in the solar output is important in understanding the connection between the emergent magnetic flux on the Sun and the radiative output as well as in understanding the effects of such change in the upper atmosphere of the earth. We present preliminary estimates of the observed changes as the means to spur inquiry into this solar event in the declining phase of solar cycle 22. Typical decreases are 15% in Lyman alpha and 40% in 10.7-cm radio flux. Mass spectrometer and incoherent scatter model calculations at 600 km in the thermosphere indicate a 30% decrease in the temperature and a 3X decrease in the density of the thermosphere near the altitude where both the Upper Atmosphere Research Satellite (UARS) and Hubble Space Telescope (HST) are flying. Decrease of the orbital period of the UARS shows the expected effect of decreasing density at flight altitude. Work in progress indicates that the output change results from the decline in solar magnetic flux to a lower level of activity in the southern hemisphere of the Sun.

Large Abundances of Polycyclic Aromatic Hydrocarbons in Titan's Upper Atmosphere

NASA Technical Reports Server (NTRS)

Lopez-Puertas, M.; Dinelli, B. M.; Adriani, A.; Funke, B.; Garcia-Comas, M.; Moriconi, M. L.; D'Aversa, E.; Boersma, C.; Allamandola, L. J.

2013-01-01

In this paper, we analyze the strong unidentified emission near 3.28 micron in Titan's upper daytime atmosphere recently discovered by Dinelli et al.We have studied it by using the NASA Ames PAH IR Spectroscopic Database. The polycyclic aromatic hydrocarbons (PAHs), after absorbing UV solar radiation, are able to emit strongly near 3.3 micron. By using current models for the redistribution of the absorbed UV energy, we have explained the observed spectral feature and have derived the vertical distribution of PAH abundances in Titan's upper atmosphere. PAHs have been found to be present in large concentrations, about (2-3) × 10(exp 4) particles / cubic cm. The identified PAHs have 9-96 carbons, with a concentration-weighted average of 34 carbons. The mean mass is approx 430 u; the mean area is about 0.53 sq. nm; they are formed by 10-11 rings on average, and about one-third of them contain nitrogen atoms. Recently, benzene together with light aromatic species as well as small concentrations of heavy positive and negative ions have been detected in Titan's upper atmosphere. We suggest that the large concentrations of PAHs found here are the neutral counterpart of those positive and negative ions, which hence supports the theory that the origin of Titan main haze layer is located in the upper atmosphere.

Structure of the middle atmosphere of Venus

NASA Astrophysics Data System (ADS)

Zasova, Ludmila

Middle atmosphere of Venus (55-100 km), its mesosphere, is the important layer of atmosphere, where 70 % of the solar energy is absorbed. Most of this absorption takes place in the upper clouds in the altitude range 58-68 km in the spectral range 0.32-0.5 µm. It leads to generation of the thermal tides, playing important role in support of the superrotation. In the frame of COSPAR model VIRA (ASR, 11,1985) the model of the thermal structure of the middle atmosphere was constructed for 5 latitude ranges, based mainly on the Pioneer Venus ORO and OIR data. Using Venera-15 Fourier Spectrometry data, which allow to retrieve the temperature and aerosol profiles in a self consistent way from each spectrum, we enable to update the model of the middle atmosphere, including the local time variation of the temperature for VIRA latitude ranges (Cosmic Research, 44, 4, 2006). From Venera-15 data it was shown that variation of temperature in the middle atmosphere is well described by thermal tides with harmonics 1, 1/2, 1/3, 1/4 Venusian day, the amplitudes and phases of which depend on latitude and altitude. The model of the upper clouds (VIRA) may also be updated using Venera-15 data. It was shown that the main latitude trend is the decreasing of the upper cloud boundary from 68 km at low latitudes to 60-62 km at high latitudes. Local time variation has a solar related dependence: 1 and 1/2 day components were revealed. Venus Express continues to obtain a lot of data, which may be used for the improvement of the model of the middle atmosphere and the clouds.

The Upper Atmosphere Research Satellite (UARS)

NASA Technical Reports Server (NTRS)

Reber, Carl A.

1993-01-01

The Upper Atmosphere Research Satellite (UARS) was launched by the Space Shuttle on September 12, 1991 into a near circular orbit at 585 km altitude inclined 57 degrees to the Equator. Measurements were initiated a few days later, including solar energy inputs to the atmosphere and vertical profiles of temperature, important minor gas species, and wind fields. The orbital parameters, combined with the sensor measurements characteristics, yield a measurement pattern that produces near global coverage with a duty cycle that periodically favors the Northern or the Southern Hemispheres. A few spacecraft and instrument anomalies have impacted the total amount of data obtained to date, but the overall performance of the mission has been very good.

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

Vortex flows in the solar chromosphere. I. Automatic detection method

NASA Astrophysics Data System (ADS)

Kato, Y.; Wedemeyer, S.

2017-05-01

Solar "magnetic tornadoes" are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role in mass and energy transport in the solar atmosphere. For this purpose, we develop a new automatic detection method for chromospheric swirls, meaning the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike existing studies that rely on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity that represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to three-dimensional numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere reveals very abundant small-scale, short-lived chromospheric vortex flows that have not been found previously by visual inspection.

The SOLAR-C Mission

NASA Astrophysics Data System (ADS)

Suematsu, Y.

2015-12-01

The Solar-C is a Japan-led international solar mission planned to be launched in mid2020. It is designed to investigate the magnetic activities of the Sun, focusing on the study in heating and dynamical phenomena of the chromosphere and corona, and also to develop an algorithm for predicting short and long term solar evolution. Since it has been revealed that the different parts of the magnetized solar atmosphere are essentially coupled, the SOLAR-C should tackle the spatial scales and temperature regimes that need to be observed in order to achieve a comprehensive physical understanding of this coupling. The science of Solar-C will greatly advance our understanding of the Sun, of basic physical processes operating throughout the universe. To dramatically improve the situation, SOLAR-C will carry three dedicated instruments; the Solar UV-Vis-IR Telescope (SUVIT), the EUV Spectroscopic Telescope (EUVST) and the High Resolution Coronal Imager (HCI), to jointly observe the entire visible solar atmosphere with essentially the same high spatial resolution (0.1-0.3 arcsec), performing high resolution spectroscopic measurements over all atmospheric regions and spectro-polarimetric measurements from the photosphere through the upper chromosphere. In addition, Solar-C will contribute to our understanding on the influence of the Sun-Earth environments with synergetic wide-field observations from ground-based and other space missions. Some leading science objectives and the mission concept, including designs of the three instruments aboard SOLAR-C will be presented.

Improved Mars Upper Atmosphere Climatology

NASA Technical Reports Server (NTRS)

Bougher, S. W.

2004-01-01

The detailed characterization of the Mars upper atmosphere is important for future Mars aerobraking activities. Solar cycle, seasonal, and dust trends (climate) as well as planetary wave activity (weather) are crucial to quantify in order to improve our ability to reasonably depict the state of the Mars upper atmosphere over time. To date, our best information is found in the Mars Global Surveyor (MGS) Accelerometer (ACC) database collected during Phase 1 (Ls = 184 - 300; F10.7 = 70 - 90) and Phase 2 (Ls = 30 - 90; F10.7 = 90 - 150) of aerobraking. This database (100 - 170 km) consists of thermospheric densities, temperatures, and scale heights, providing our best constraints for exercising the coupled Mars General Circulation Model (MGCM) and the Mars Thermospheric General Circulation Model (MTGCM). The Planetary Data System (PDS) contains level 0 and 2 MGS Accelerometer data, corresponding to atmospheric densities along the orbit track. Level 3 products (densities, temperatures, and scale heights at constant altitudes) are also available in the PDS. These datasets provide the primary model constraints for the new MGCM-MTGCM simulations summarized in this report. Our strategy for improving the characterization of the Mars upper atmospheres using these models has been three-fold : (a) to conduct data-model comparisons using the latest MGS data covering limited climatic and weather conditions at Mars, (b) to upgrade the 15-micron cooling and near-IR heating rates in the MGCM and MTGCM codes for ad- dressing climatic variations (solar cycle and seasonal) important in linking the lower and upper atmospheres (including migrating tides), and (c) to exercise the detailed coupled MGCM and MTGCM codes to capture and diagnose the planetary wave (migrating plus non-migrating tidal) features throughout the Mars year. Products from this new suite of MGCM-MTGCM coupled simulations are being used to improve our predictions of the structure of the Mars upper atmosphere for the upcoming MRO aerobraking exercises in 2006. A Michigan website, containing MTGCM output fields from previous climate simulations, is being expanded to include new MGCM-MTGCM simulations addressing planetary wave influences upon thermospheric aerobraking fields (densities and temperatures). In addition, similar MTGCM output fields have been supplied to the MSFC MARSGRAM - 200X empirical model, which will be used in mission operations for conducting aerobraking maneuvers.

The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

NASA Technical Reports Server (NTRS)

Ishikawa, Shin-nosuke; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N..; Ishikawa, R.; Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Hara, H.;

Tracking Waves from Sunspots Gives New Solar Insight

NASA Image and Video Library

2017-12-08

While it often seems unvarying from our viewpoint on Earth, the sun is constantly changing. Material courses through not only the star itself, but throughout its expansive atmosphere. Understanding the dance of this charged gas is a key part of better understanding our sun – how it heats up its atmosphere, how it creates a steady flow of solar wind streaming outward in all directions, and how magnetic fields twist and turn to create regions that can explode in giant eruptions. Now, for the first time, researchers have tracked a particular kind of solar wave as it swept upward from the sun's surface through its atmosphere, adding to our understanding of how solar material travels throughout the sun. Scientists analyzed sunspot images from a trio of observatories -- including the Big Bear Solar Observatory, which captured this footage -- to make the first-ever observations of a solar wave traveling up into the sun’s atmosphere from a sunspot. Tracking solar waves like this provides a novel tool for scientists to study the atmosphere of the sun. The imagery of the journey also confirms existing ideas, helping to nail down the existence of a mechanism that moves energy – and therefore heat – into the sun’s mysteriously-hot upper atmosphere, called the corona. A study on these results was published Oct. 11, 2016, in The Astrophysical Journal Letters. Image credit: Zhao et al/NASA/SDO/IRIS/BBSO Read more: go.nasa.gov/2dRv80g NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma

NASA Astrophysics Data System (ADS)

Balmaceda, L.; Vargas Domínguez, S.; Palacios, J.; Cabello, I.; Domingo, V.

2010-04-01

Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic flux tubes. We report the observation of magnetic concentrations being dragged towards the center of a convective vortex motion in the solar photosphere from high-resolution ground-based and space-borne data. We describe this event by analyzing a series of images at different solar atmospheric layers. By computing horizontal proper motions, we detect a vortex whose center appears to be the draining point for the magnetic concentrations detected in magnetograms and well-correlated with the locations of bright points seen in G-band and CN images.

Martian Atmospheric and Ionospheric plasma Escape

NASA Astrophysics Data System (ADS)

Lundin, Rickard

2016-04-01

Solar forcing is responsible for the heating, ionization, photochemistry, and erosion processes in the upper atmosphere throughout the lifetime of the terrestrial planets. Of the four terrestrial planets, the Earth is the only one with a fully developed biosphere, while our kin Venus and Mars have evolved into arid inhabitable planets. As for Mars, there are ample evidences for an early Noachian, water rich period on Mars. The question is, what made Mars evolve so differently compared to the Earth? Various hydrosphere and atmospheric evolution scenarios for Mars have been forwarded based on surface morphology, chemical composition, simulations, semi-empiric (in-situ data) models, and the long-term evolution of the Sun. Progress has been made, but the case is still open regarding the changes that led to the present arid surface and tenuous atmosphere at Mars. This presentation addresses the long-term variability of the Sun, the solar forcing impact on the Martian atmosphere, and its interaction with the space environment - an electromagnetic wave and particle interaction with the upper atmosphere that has implications for its photochemistry, composition, and energization that governs thermal and non-thermal escape. Non-thermal escape implies an electromagnetic upward energization of planetary ions and molecules to velocities above escape velocity, a process governed by a combination of solar EUV radiation (ionization), and energy and momentum transfer by the solar wind. The ion escape issue dates back to the early Soviet and US-missions to Mars, but the first more accurate estimates of escape rates came with the Phobos-2 mission in 1989. Better-quality ion composition measurement results of atmospheric/ionospheric ion escape from Mars, obtained from ESA Mars Express (MEX) instruments, have improved our understanding of the ion escape mechanism. With the NASA MAVEN spacecraft orbiting Mars since Sept. 2014, dual in-situ measurement with plasma instruments are now carried out in the Martian planetary realm. Of particular interest from a planetary atmospheric escape point of view is the long-term implications of solar forcing. From ASPERA-data on MEX it has been possible to cover the transition from cycle 23 up to the cycle 24 maximum, data displaying clear solar cycle dependence. The planetary ion escape rate increased from solar minimum to solar maximum by a factor of 10. From a regression analysis using ion escape fluxes and solar forcing proxies, a "back-casting" tool is developed [1], enabling determination of the planetary ion escape back in time based on long-term solar forcing proxies (F10.7, sunspot number). The tool may be applied to other long-term solar proxies, such as the radiogenic isotopes in the Earth's atmosphere, 10Be and 14C. The cosmic-ray production of these long-lifetime (>10000 year) isotopes is modulated by the solar-heliospheric magnetic flux, i.e. an indirect measure of solar magnetic activity. Beyond that there is so far only one additional rough "back-casting" tool, the "Sun-in-time", a method whereby the age of, EUV/UV radiation, and mass-loss of other sun-like stars are determined [2, 3]. [1] Lundin et al., Geophys. Res. Lett., 40, 23, pp. 6028-6032, 2013. [2] Wood et al., ApJ, 574:412-425, 2002. [3] Ribas et al., ApJ., 622:680-694, 2005

Space Weather Studies at Istanbul Technical University

NASA Astrophysics Data System (ADS)

Kaymaz, Zerefsan

2016-07-01

This presentation will introduce the Upper Atmosphere and Space Weather Laboratory of Istanbul Technical University (ITU). It has been established to support the educational needs of the Faculty of Aeronautics and Astronautics in 2011 to conduct scientific research in Space Weather, Space Environment, Space Environment-Spacecraft Interactions, Space instrumentation and Upper Atmospheric studies. Currently the laboratory has some essential infrastructure and the most instrumentation for ionospheric observations and ground induced currents from the magnetosphere. The laboratory has two subunits: SWIFT dealing with Space Weather Instrumentation and Forecasting unit and SWDPA dealing with Space Weather Data Processing and Analysis. The research area covers wide range of upper atmospheric and space science studies from ionosphere, ionosphere-magnetosphere coupling, magnetic storms and magnetospheric substorms, distant magnetotail, magnetopause and bow shock studies, as well as solar and solar wind disturbances and their interaction with the Earth's space environment. We also study the spacecraft environment interaction and novel plasma instrument design. Several scientific projects have been carried out in the laboratory. Operational objectives of our laboratory will be carried out with the collaboration of NASA's Space Weather Laboratory and the facilities are in the process of integration to their prediction services. Educational and research objectives, as well as the examples from the research carried out in our laboratory will be demonstrated in this presentation.

VANDENBERG AIR FORCE BASE, CALIF. - At Vandenberg AFB, Calif., a solar array is tested before installing on the SciSat-1 spacecraft. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-29

VANDENBERG AIR FORCE BASE, CALIF. - At Vandenberg AFB, Calif., a solar array is tested before installing on the SciSat-1 spacecraft. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

VANDENBERG AIR FORCE BASE, CALIF. - At Vandenberg AFB, Calif., a solar array is installed on the SciSat-1 spacecraft. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-29

VANDENBERG AIR FORCE BASE, CALIF. - At Vandenberg AFB, Calif., a solar array is installed on the SciSat-1 spacecraft. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

Atomic Oxygen Density Retrievals using FUV Observations by the Imaging Ultraviolet Spectrograph on MAVEN

NASA Astrophysics Data System (ADS)

Evans, J. Scott; Stevens, Michael H.; Schneider, Nicholas M.; Stewart, Ian; Deighan, Justin; Jain, Sonal Kumar; Eparvier, Francis; Thiemann, E. M.; Bougher, Stephen W.; Jakosky, Bruce

2016-10-01

We present the first direct retrievals of neutral atomic oxygen in Mars's upper atmosphere using daytime FUV periapse limb scan observations from 130 - 200 km tangent altitude. Atmospheric composition is inferred using the Atmospheric Ultraviolet Radiance Integrated Code [Strickland et al., 1999] adapted to the Martian atmosphere [Evans et al., 2015]. For our retrievals we use O I 135.6 nm emission observed by IUVS on MAVEN under daytime conditions (solar zenith angle < 60 degrees) over both northern and southern hemispheres (latitudes between -65 and +35 degrees) from October 2014 to August 2016. We investigate the sensitivity of atomic oxygen density retrievals to variability in solar irradiance, solar longitude, and local time. We compare our retrievals to predictions from the Mars Global Ionosphere-Thermosphere Model [MGITM, Bougher et al., 2015] and the Mars Climate Database [MCD, Forget et al., 1999] and quantify the differences throughout the altitude region of interest. The retrieved densities are used to characterize global transport of atomic oxygen in the Martian thermosphere.

The Jovian atmospheric window at 2.7 microns: A search for H2S

NASA Technical Reports Server (NTRS)

Larson, H. P.; Davis, D. S.; Hofmann, R.; Bjoraker, G. L.

1984-01-01

The atmospheric transmission window at 2.7 microns in Jupiter's atmosphere was observed at a spectral resolution of 0.1/cm from the Kuiiper Airborne Observatory. From an analysis of the CH4 abundance (80 m-am) and the H2O abundance ( 0.0125 cm-am) it was determined that the penetration depth of solar flux at 2.7 microns is near the base of the NH3 cloud layer. The upper limit to H2O at 2.7 microns and other results suggest that photolytic reactions in Jupiter's lower troposphere may not be as significant as was previously thought. A search for H2S in Jupiter's atmosphere yielded an upper limit of 0.1 cm-am. The corresponding limit to the element abundance ratio S/H was approx. 1.7x10(-8), about 10(-3) times the solar value. Upon modeling the abundance and distribution of H2S in Jupiter's atmosphere it was concluded that, contrary to expectations, sulfur-bearing chromophores are not present in significant amounts in Jupiter's visible clouds. Rather, it appears that most of Jupiter's sulfur is locked up as NH4SH in a lower cloud layer. Alternatively, the global abundance of sulfur in Jupiter may be significantly depleted.

Near-Mars space

NASA Astrophysics Data System (ADS)

Luhmann, J. G.; Brace, L. H.

1991-05-01

The prevalent attributes of near-Mars space are described: the ambient interplanetary environment, the ionosphere, the upper atmosphere, and more remote regions that are affected by the presence of Mars. The descriptions are based on existing Martian data and/or models constructed from measurements made near Venus. Specific attention is given to the features of solar wind interaction with magnetospheric and ionospheric obstacles. The high-altitude plasma and field environment, the energetic particle environment, the ionosphere environment, and the neutral upper atmosphere environment are described with extensive graphic information, based on existing measurements collected from nine Martian missions. The ionospheric obstacle is assumed to prevail as a mechanism for describing the scenario. Martian perturbation of solar wind is theorized to be of a relatively small order. A distinctive local energetic particle population of planetary origin is shown to result from the direct interaction of solar wind plasma. This phenomenon is considered evidence of the important scavenging of planetary elements from Mars. The absence of a planetary dipole field around Mars, like its low gravity and distance from the sun, is considered important in determining the environment of this earthlike laboratory.

SAGE III Educational Outreach and Student's On-Line Atmospheric Research

NASA Astrophysics Data System (ADS)

Woods, D. C.; Moore, S. W.; Walters, S. C.

2002-05-01

Students On-Line Atmospheric Research (SOLAR) is a NASA-sponsored educational outreach program aimed at raising the level of interest in science among elementary, middle, and high school students. SOLAR is supported by, and closely linked to, NASA's Stratospheric Aerosol and Gas Experiment III (SAGE III). SAGE III, launched on a Russian METEOR 3M spacecraft in December 2001, is a key component of NASA's Earth Observing System. It will monitor the quantity and distribution of aerosols, ozone, clouds, and other important trace gases in the upper atmosphere. Early data from SAGE III indicate that the instrument is performing as expected. SAGE III measurements will extend the long-term data record established by its predecessors, SAGE I and SAGE II, which spans from 1979 to the present. In addition, SAGE III's added measurement capabilities will provide more detailed data on certain atmospheric species. SOLAR selects interesting topics related to the science issues addressed by the SAGE III experiments, and develops educational materials and projects to enhance science teaching, and to help students realize the relevance of these issues to our lives on Earth. For example, SOLAR highlights some of the major questions regarding the health of the atmosphere such as possible influences of aerosols on global climate, and atmospheric processes related to ozone depletion. The program features projects to give students hands-on experience with scientific equipment and help develop skills in collecting, analyzing, and reporting science results. SOLAR focuses on helping teachers become familiar with current research in the atmospheric sciences, helping teachers integrate SOLAR developed educational materials into their curriculum. SOLAR gives special presentations at national and regional science teacher conferences and conducts a summer teacher workshop at the NASA Langley Research Center. This poster will highlight some of the key features of the SOLAR program and will present descriptions of student projects, teacher workshops, and SOLAR resources.

Solar wind and high energy particle effects in the middle atmosphere

NASA Technical Reports Server (NTRS)

Lastovicka, Jan

1989-01-01

The solar wind variability and high energy particle effects in the neutral middle atmosphere are not much known. These factors are important in the high latitude upper mesosphere, lower thermosphere energy budget. They influence temperature, composition (minor constituents of nitric oxide, ozone), circulation (wind system) and airflow. The vertical and latitudinal structures of such effects, mechanisms of downward penetration of energy and questions of energy abundance are largely to be solved. The most important recent finding seems to be the discovery of the role of highly relativistic electrons in the middle atmosphere at L = 3 - 8 (Baker et al., 1987). The solar wind and high energy particle flux variability appear to form a part of the chain of possible Sun-weather (climate) relationships. The importance of such studies in the nineties is emphasized by their role in big international programs STEP and IGBP - Global Change.

Local time variations of the middle atmosphere of Venus: Solar-related structures

NASA Astrophysics Data System (ADS)

Zasova, L.; Khatountsev, I. V.; Ignatiev, N. I.; Moroz, V. I.

Three-dimensional fields (latitude — altitude — local time) of temperature and aerosol in the upper clouds, obtained from the Venera-15 IR spectrometry data, were studied to search for the solar-related structures. The temperature variation at the isobaric levels vs. solar longitude was presented as a superposition of the cosines with periods of 1, 1/2, 1/3 and 1/4 Venusian days. At low latitudes the diurnal tidal component reaches a maximum above 0.2 mb (92km) level. At high latitudes it dominates at P> 50 mb (68 km) in the cold collar, being roughly twice as much as the semidiurnal one and passing through the maximum of 13 K at 400 mb (57 km). The semidiurnal tidal amplitude exceeds the diurnal one below 90 km (where its maximum locates near 83 km), and also in the upper clouds, above 58 km. At low latitudes the 1/3 days component predominates at 10 - 50 mb (68-76 km). In the upper clouds, where most of the solar energy, absorbed in the middle atmosphere, deposits, all four tidal components, including wavenumbers 3 and 4, have significant amplitudes. A position of the upper boundary of the clouds depends on local time in such a way that the lowest height of the clouds is observed in the morning at all selected latitude ranges. At low latitudes the highest position of the upper boundary of the clouds (at 1218 cm -1) is found at 8 - 9 PM, whereas the lowest one is near the morning terminator. At high latitudes the lowest position of the upper boundary of the clouds shifts towards the dayside being at 10:30 AM at 75° in the cold collar and the highest one shifts to 4 PM. The zonal mean altitude of the upper boundary of the clouds decreases from 69 km at 15° to 59 km at 75°. The diurnal tidal component has the highest amplitude in the cold collar (1.5 km). At low latitudes both amplitudes, diurnal and semidiurnal, reach the values 0.8 - 1 km.

Broad band solar EUV absorption in the earth's upper atmosphere.

NASA Technical Reports Server (NTRS)

Allen, K. H.; Rense, W. A.

1973-01-01

Observation data on solar radiation intensity, based on measurements performed as a function of time for three broad wavelength bands between 280 and 1030 A by a wheel spectrometer on Oso 5 during sunrise and sunset, are compared with predicted intensity variations based on Cira models. The differences between sunrise and sunset data, as well as those between observed and predicted data are discussed.

Mars environment and magnetic orbiter scientific and measurement objectives.

PubMed

Leblanc, F; Langlais, B; Fouchet, T; Barabash, S; Breuer, D; Chassefière, E; Coates, A; Dehant, V; Forget, F; Lammer, H; Lewis, S; Lopez-Valverde, M; Mandea, M; Menvielle, M; Pais, A; Paetzold, M; Read, P; Sotin, C; Tarits, P; Vennerstrom, S

2009-01-01

In this paper, we summarize our present understanding of Mars' atmosphere, magnetic field, and surface and address past evolution of these features. Key scientific questions concerning Mars' surface, atmosphere, and magnetic field, along with the planet's interaction with solar wind, are discussed. We also define what key parameters and measurements should be performed and the main characteristics of a martian mission that would help to provide answers to these questions. Such a mission--Mars Environment and Magnetic Orbiter (MEMO)--was proposed as an answer to the Cosmic Vision Call of Opportunity as an M-class mission (corresponding to a total European Space Agency cost of less than 300 Meuro). MEMO was designed to study the strong interconnection between the planetary interior, atmosphere, and solar conditions, which is essential to our understanding of planetary evolution, the appearance of life, and its sustainability. The MEMO main platform combined remote sensing and in situ measurements of the atmosphere and the magnetic field during regular incursions into the martian upper atmosphere. The micro-satellite was designed to perform simultaneous in situ solar wind measurements. MEMO was defined to conduct: * Four-dimensional mapping of the martian atmosphere from the surface up to 120 km by measuring wind, temperature, water, and composition, all of which would provide a complete view of the martian climate and photochemical system; Mapping of the low-altitude magnetic field with unprecedented geographical, altitude, local time, and seasonal resolutions; A characterization of the simultaneous responses of the atmosphere, magnetic field, and near-Mars space to solar variability by means of in situ atmospheric and solar wind measurements.

IUE observations of the Jovian dayglow emission

NASA Technical Reports Server (NTRS)

Mcgrath, M. A.; Feldman, P. D.; Ballester, G. E.; Moos, H. W.

1989-01-01

IUE spectra of Jupiter are examined in light of recent models put forward to explain the anomalously bright ultraviolet emissions seen from the upper atmospheres of the outer planets. Chi-squared fits of the IUE spectra with model spectra produced by two proposed excitation mechanisms, electron impact and fluorescence of solar radiation, result in consistently higher chi-squared values for the solar fluorescence model. No conclusive evidence is found in the IUE data for the dominance of solar fluorescence over electron excitation in producing the Jovian dayglow emission.

Solar F10.7 radiation - A short term model for Space Station applications

NASA Technical Reports Server (NTRS)

Vedder, John D.; Tabor, Jill L.

1991-01-01

A new method is described for statistically modeling the F10.7 component of solar radiation for 91-day intervals. The resulting model represents this component of the solar flux as a quasi-exponentially correlated, Weibull distributed random variable, and thereby demonstrates excellent agreement with observed F10.7 data. Values of the F10.7 flux are widely used in models of the earth's upper atmosphere because of its high correlation with density fluctuations due to solar heating effects. Because of the direct relation between atmospheric density and drag, a realistic model of the short term fluctuation of the F10.7 flux is important for the design and operation of Space Station Freedom. The method of modeling this flux described in this report should therefore be useful for a variety of Space Station applications.

Midlatitude atmospheric OH response to the most recent 11-y solar cycle.

PubMed

Wang, Shuhui; Li, King-Fai; Pongetti, Thomas J; Sander, Stanley P; Yung, Yuk L; Liang, Mao-Chang; Livesey, Nathaniel J; Santee, Michelle L; Harder, Jerald W; Snow, Martin; Mills, Franklin P

2013-02-05

The hydroxyl radical (OH) plays an important role in middle atmospheric photochemistry, particularly in ozone (O(3)) chemistry. Because it is mainly produced through photolysis and has a short chemical lifetime, OH is expected to show rapid responses to solar forcing [e.g., the 11-y solar cycle (SC)], resulting in variabilities in related middle atmospheric O(3) chemistry. Here, we present an effort to investigate such OH variability using long-term observations (from space and the surface) and model simulations. Ground-based measurements and data from the Microwave Limb Sounder on the National Aeronautics and Space Administration's Aura satellite suggest an ∼7-10% decrease in OH column abundance from solar maximum to solar minimum that is highly correlated with changes in total solar irradiance, solar Mg-II index, and Lyman-α index during SC 23. However, model simulations using a commonly accepted solar UV variability parameterization give much smaller OH variability (∼3%). Although this discrepancy could result partially from the limitations in our current understanding of middle atmospheric chemistry, recently published solar spectral irradiance data from the Solar Radiation and Climate Experiment suggest a solar UV variability that is much larger than previously believed. With a solar forcing derived from the Solar Radiation and Climate Experiment data, modeled OH variability (∼6-7%) agrees much better with observations. Model simulations reveal the detailed chemical mechanisms, suggesting that such OH variability and the corresponding catalytic chemistry may dominate the O(3) SC signal in the upper stratosphere. Continuing measurements through SC 24 are required to understand this OH variability and its impacts on O(3) further.

Midlatitude atmospheric OH response to the most recent 11-y solar cycle

PubMed Central

Wang, Shuhui; Li, King-Fai; Pongetti, Thomas J.; Sander, Stanley P.; Yung, Yuk L.; Liang, Mao-Chang; Livesey, Nathaniel J.; Santee, Michelle L.; Harder, Jerald W.; Snow, Martin; Mills, Franklin P.

2013-01-01

The hydroxyl radical (OH) plays an important role in middle atmospheric photochemistry, particularly in ozone (O3) chemistry. Because it is mainly produced through photolysis and has a short chemical lifetime, OH is expected to show rapid responses to solar forcing [e.g., the 11-y solar cycle (SC)], resulting in variabilities in related middle atmospheric O3 chemistry. Here, we present an effort to investigate such OH variability using long-term observations (from space and the surface) and model simulations. Ground-based measurements and data from the Microwave Limb Sounder on the National Aeronautics and Space Administration’s Aura satellite suggest an ∼7–10% decrease in OH column abundance from solar maximum to solar minimum that is highly correlated with changes in total solar irradiance, solar Mg-II index, and Lyman-α index during SC 23. However, model simulations using a commonly accepted solar UV variability parameterization give much smaller OH variability (∼3%). Although this discrepancy could result partially from the limitations in our current understanding of middle atmospheric chemistry, recently published solar spectral irradiance data from the Solar Radiation and Climate Experiment suggest a solar UV variability that is much larger than previously believed. With a solar forcing derived from the Solar Radiation and Climate Experiment data, modeled OH variability (∼6–7%) agrees much better with observations. Model simulations reveal the detailed chemical mechanisms, suggesting that such OH variability and the corresponding catalytic chemistry may dominate the O3 SC signal in the upper stratosphere. Continuing measurements through SC 24 are required to understand this OH variability and its impacts on O3 further. PMID:23341617

Dependence of Photochemical Escape of Oxygen at Mars on Solar Radiation and Solar Wind Interaction

NASA Astrophysics Data System (ADS)

Cravens, T.; Rahmati, A.; Lillis, R. J.; Fox, J. L.; Bougher, S. W.; Jakosky, B. M.

2016-12-01

The evolution of the atmosphere of Mars and the loss of volatiles over the life of the solar system is a key topic in planetary science. An important loss process in the ionosphere is photochemical escape. In particular, dissociative recombination of O2+ ions (the major ion species) produces fast oxygen atoms, some of which can escape from the planet. Several theoretical models have been constructed over the years to study hot oxygen and its escape from Mars. These model have a number of uncertainties, particularly for the elastic cross sections of O collisions with target neutral species. Recently, the Mars Atmosphere and Volatile Evolution Mission (MAVEN) mission has been rapidly improving our understanding of the upper atmosphere and ionosphere of Mars and its interaction with the external environment (e.g., the solar wind). The purpose of the current paper is to take a simple analytical approach to the oxygen escape problem in order to: (1) study the role that solar flux and solar wind variations have on escape and (2) isolate the effects of uncertainties in oxygen cross sections on the derived oxygen escape rates. Not surprisingly, we find, in agreement with more elaborate numerical models, that the escape flux is directly proportional to the incident solar extreme ultraviolet irradiance and is inversely proportional to the backscatter elastic cross section. The role for atmospheric loss that ion transport plays in the topside ionosphere and how the solar wind interaction drives this will also be discussed.

The satellite power system - Assessment of the environmental impact on middle atmosphere composition and on climate

NASA Technical Reports Server (NTRS)

Whitten, R. C.; Borucki, W. J.; Park, C.; Pfister, L.; Woodward, H. T.; Turco, R. P.; Capone, L. A.; Riegel, C. A.; Kropp, T.

1982-01-01

Numerical models were developed to calculate the total deposition of watervapor, hydrogen, CO2, CO, SO2, and NO in the middle atmosphere from operation of heavy lift launch vehicles (HLLV) used to build a satellite solar power system (SPS). The effects of the contaminants were examined for their effects on the upper atmosphere. One- and two-dimensional models were formulated for the photochemistry of the upper atmosphere and for rocket plumes and reentry. An SPS scenario of 400 launches per year for 10 yr was considered. The build-up of the contaminants in the atmosphere was projected to have no significant effects, even at the launch latitude. Neither would there by any dangerous ozone depletion. It was found that H, OH, and HO2 species would double in the thermosphere. No measurable changes in climate were foreseen.

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

Wuebbles, D.J.; Kinnison, D.E.; Lean, J.L.

Over the past decade, knowledge of the magnitude and temporal structure of the variations in the sun's ultraviolet irradiance has increased steadily. A number of theoretical modeling studies have shown that changes in the solar ultraviolet flux during the 11-year solar cycle can have a significant effect on stratospheric ozone concentrations. With the exception of Brasseur et al., who examined a very broad range of solar flux variations, all of these studies assumed much larger changes in the ultraviolet flux than measurements now indicate. These studies either calculated the steady-state effect at solar maximum and solar minimum or assumed sinusoidalmore » variations in the solar flux changes with time. It is now possible to narrow the uncertainty range of the expected effects on upper stratospheric ozone and temperature resulting from the 11-year solar cycle. A more accurate representation of the solar flux changes with time is used in this analysis, as compared to previous published studies. This study also evaluates the relative roles of solar flux variations and increasing concentrations of long-lived trace gases in determining the observed trends in upper stratospheric ozone and temperature. The LLNL two-dimensional chemical-radiative-transport model of the global atmosphere is used to evaluate the combined effects on the stratosphere from changes in solar ultraviolet irradiances and trace gas concentrations over the last several decades. Derived trends in upper stratospheric ozone concentrations and temperature are then compared with available analyses of ground-based and satellite measurements over this time period.« less

Diffusion in the chromosphere and the composition of the solar corona and energetic particles

NASA Technical Reports Server (NTRS)

Vauclair, S.; Meyer, J. P.

1985-01-01

Composition observations, in the solar photosphere, and in the upper transition region (TR) and corona imply a change of composition of the solar atmosphere somewhere between the photosphere and the upper TR. Heavy elements with first ionization potential (FIP) 9 eV (high-FIP element) are approx. 4 times less abundant in the TR and corona than in the photosphere, as compared to both hydrogen and heavy elements with lower low-FIP elements. A separation is suggested between neutral and ionized elements in a region where the high-FIP elements are mostly neutral, and the low-FIP elements ionized. This occurs in the chromosphere at altitudes above 600 km and below 2000 km above Photosphere. Whether the diffusion processes can explain the observed change in composition is investigated.

Comparative studies of the interaction between the Sun and planetary near space environments with the Solar Connections Observatory for Planetary Environments (SCOPE)

NASA Astrophysics Data System (ADS)

Harris, W. M.; Scope Team

2003-04-01

The Solar Connections Observatory for Planetary Environments (SCOPE) is a remote sensing facility designed to probe the nature of the relationship of planetary bodies and the local interstellar medium to the solar wind and UV-EUV radiation field. In particular, the SCOPE program seeks to comparatively monitor the near space environments and thermosphere/ionospheres of planets, planetesimals, and satellites under different magnetospheric configurations and as a function of heliocentric distance and solar activity. In addition, SCOPE will include the Earth as a science target, providing new remote observations of auroral and upper atmospheric phenomena and utilizing it as baseline for direct comparison with other planetary bodies. The observatory will be scheduled into discrete campaigns interleaving Target-Terrestrial observations to provide a comparative annual activity map over the course of a solar half cycle. The SCOPE science instrument consists of binocular UV (115-310 nm) and EUV (500-120 nm) telescopes and a side channel sky-mapping interferometer on a spacecraft stationed in a remote orbit. The telescope instruments provide a mix of capabilities including high spatial resolution narrow band imaging, moderate resolution broadband spectro-imaging, and high-resolution line spectroscopy. The side channel instrument will be optimized for line profile measurements of diagnostic terrestrial upper atmospheric, comet, interplanetary, and interstellar extended emissions.

Accumulation of electric currents driving jetting events in the solar atmosphere

NASA Astrophysics Data System (ADS)

Vargas Domínguez, S.; Guo, Y.; Demoulin, P.; Schmieder, B.; Ding, M.; Liu, Y.

2013-12-01

The solar atmosphere is populated with a wide variety of structures and phenomena at different spatial and temporal scales. Explosive phenomena are of particular interest due to their contribution to the atmosphere's energy budget and their implications, e.g. coronal heating. Recent instrumental developments have provided important observations and therefore new insights for tracking the dynamic evolution of the solar atmosphere. Jets of plasma are frequently observed in the solar corona and are thought to be a consequence of magnetic reconnection, however, the physics involved is not fully understood. Unprecedented observations (EUV and vector magnetic fields) are used to study solar jetting events, from which we derive the magnetic flux evolution, the photospheric velocity field, and the vertical electric current evolution. The evolution of magnetic parasitic polarities displaying diverging flows are detected to trigger recurrent jets in a solar regionon 17 September 2010. The interaction drive the build up of electric currents. Observed diverging flows are proposed to build continuously such currents. Magnetic reconnection is proposed to occur periodically, in the current layer created between the emerging bipole and the large scale active region field. SDO/AIA EUV composite images. Upper: SDO/AIA 171 Å image overlaid by the line-of-sight magnetic field observed at the same time as that of the 171 Å image. Lower: Map of photospheric transverse velocities derived from LCT analysis with the HMI magnetograms.

ATLAS 1: Encountering Planet Earth

NASA Technical Reports Server (NTRS)

Shea, Charlotte; Mcmahan, Tracy; Accardi, Denise; Tygielski, Michele; Mikatarian, Jeff; Wiginton, Margaret (Editor)

1984-01-01

Several NASA science programs examine the dynamic balance of sunlight, atmosphere, water, land, and life that governs Earth's environment. Among these is a series of Space Shuttle-Spacelab missions, named the Atmospheric Laboratory for Applications and Science (ATLAS). During the ATLAS missions, international teams of scientists representing many disciplines combine their expertise to seek answers to complex questions about the atmospheric and solar conditions that sustain life on Earth. The ATLAS program specifically investigates how Earth's middle atmosphere and upper atmospheres and climate are affected by both the Sun and by products of industrial and agricultural activities on Earth.

Thermosphere-Ionosphere-Mesosphere Modeling Using the TIE-GCM, TIME-GCM, and WACCM That Will Lead to the Development of a Seamless Model of the Whole Atmosphere

DTIC Science & Technology

2006-09-30

disturbances from the lower atmosphere and ocean affect the upper atmosphere and how this variability interacts with the variability generated by solar and...represents “ general circulation model.” Both models include self-consistent ionospheric electrodynamics, that is, a calculation of the electric fields...and currents generated by the ionospheric dynamo, and consideration of their effects on the neutral dynamics. The TIE-GCM is used for studies that

Organic chemistry in Titan's upper atmosphere and its astrobiological consequences: I. Views towards Cassini plasma spectrometer (CAPS) and ion neutral mass spectrometer (INMS) experiments in space

NASA Astrophysics Data System (ADS)

Ali, A.; Sittler, E. C.; Chornay, D.; Rowe, B. R.; Puzzarini, C.

2015-05-01

The discovery of carbocations and carbanions by Ion Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) instruments onboard the Cassini spacecraft in Titan's upper atmosphere is truly amazing for astrochemists and astrobiologists. In this paper we identify the reaction mechanisms for the growth of the complex macromolecules observed by the CAPS Ion Beam Spectrometer (IBS) and Electron Spectrometer (ELS). This identification is based on a recently published paper (Ali et al., 2013. Planet. Space Sci. 87, 96) which emphasizes the role of Olah's nonclassical carbonium ion chemistry in the synthesis of the organic molecules observed in Titan's thermosphere and ionosphere by INMS. The main conclusion of that work was the demonstration of the presence of the cyclopropenyl cation - the simplest Huckel's aromatic molecule - and its cyclic methyl derivatives in Titan's atmosphere at high altitudes. In this study, we present the transition from simple aromatic molecules to the complex ortho-bridged bi- and tri-cyclic hydrocarbons, e.g., CH2+ mono-substituted naphthalene and phenanthrene, as well as the ortho- and peri-bridged tri-cyclic aromatic ring, e.g., perinaphthenyl cation. These rings could further grow into tetra-cyclic and the higher order ring polymers in Titan's upper atmosphere. Contrary to the pre-Cassini observations, the nitrogen chemistry of Titan's upper atmosphere is found to be extremely rich. A variety of N-containing hydrocarbons including the N-heterocycles where a CH group in the polycyclic rings mentioned above is replaced by an N atom, e.g., CH2+ substituted derivative of quinoline (benzopyridine), are found to be dominant in Titan's upper atmosphere. The mechanisms for the formation of complex molecular anions are discussed as well. It is proposed that many closed-shell complex carbocations after their formation first, in Titan's upper atmosphere, undergo the kinetics of electron recombination to form open-shell neutral radicals. These radical species subsequently might form carbanions via radiative electron attachment at low temperatures with thermal electrons. The classic example is the perinaphthenyl anion in Titan's upper atmosphere. Therefore, future astronomical observations of selected carbocations and corresponding carbanions are required to settle the key issue of molecular anion chemistry on Titan. Other than earth, Titan is the only planetary body in our solar system that is known to have reservoirs of permanent liquids on its surface. The synthesis of complex biomolecules either by organic catalysis of precipitated solutes “on hydrocarbon solvent” on Titan or through the solvation process indeed started in its upper atmosphere. The most notable examples in Titan's prebiotic atmospheric chemistry are conjugated and aromatic polycyclic molecules, N-heterocycles including the presence of imino >Cdbnd N-H functional group in the carbonium chemistry. Our major conclusion in this paper is that the synthesis of organic compounds in Titan's upper atmosphere is a direct consequence of the chemistry of carbocations involving the ion-molecule reactions. The observations of complexity in the organic chemistry on Titan from the Cassini-Huygens mission clearly indicate that Titan is so far the only planetary object in our solar system that will most likely provide an answer to the question of the synthesis of complex biomolecules on the primitive earth and the origin of life.

KSC-2013-3597

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3598

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3596

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3600

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3601

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3599

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3595

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

Simulation of the 21 August 2017 Solar Eclipse Using the Whole Atmosphere Community Climate Model-eXtended

NASA Astrophysics Data System (ADS)

McInerney, Joseph M.; Marsh, Daniel R.; Liu, Han-Li; Solomon, Stanley C.; Conley, Andrew J.; Drob, Douglas P.

2018-05-01

We performed simulations of the atmosphere-ionosphere response to the solar eclipse of 21 August 2017 using the Whole Atmosphere Community Climate Model-eXtended (WACCM-X v. 2.0) with a fully interactive ionosphere and thermosphere. Eclipse simulations show temperature changes in the path of totality up to -3 K near the surface, -1 K at the stratopause, ±4 K in the mesosphere, and -40 K in the thermosphere. In the F region ionosphere, electron density is depleted by about 55%. Both the temperature and electron density exhibit global effects in the hours following the eclipse. There are also significant effects on stratosphere-mesosphere chemistry, including an increase in ozone by nearly a factor of 2 at 65 km. Dynamical impacts of the eclipse in the lower atmosphere appear to propagate to the upper atmosphere. This study provides insight into coupled eclipse effects through the entire atmosphere from the surface through the ionosphere.

Preparation of IHY-2007 in Indonesia: Local Observational Facilities, International Collaborations, and the Use of International Data

NASA Astrophysics Data System (ADS)

Djamaluddin, T.

2006-11-01

t_djamal@hotmail.com Since 1980, the National Institute of Aeronautics and Space (LAPAN) has been carrying out integrated observations of solar activities, geomagnetic disturbance, and ionospheric parameters, as well as other solar-terrestrial relationship research. International collaboration, especially with Japan in the field of solar physics, geomagnetism and equatorial atmosphere and with Australia in the field of ionosphere and upper atmosphere, help us in increasing national capacity building. The international data available on the Internet also helps us in comparing our local data with the global one or in fulfilling our needs of data due to lack of facilities, ground based or space based data. Some results will be reviewed. Preparation for IHY-2007 will also be discussed.

Non-thermal hydrogen atoms in the terrestrial upper thermosphere.

PubMed

Qin, Jianqi; Waldrop, Lara

2016-12-06

Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere.

Non-thermal hydrogen atoms in the terrestrial upper thermosphere

PubMed Central

Qin, Jianqi; Waldrop, Lara

2016-01-01

Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere. PMID:27922018

Atmospheric-radiation boundary conditions for high-frequency waves in time-distance helioseismology

NASA Astrophysics Data System (ADS)

Fournier, D.; Leguèbe, M.; Hanson, C. S.; Gizon, L.; Barucq, H.; Chabassier, J.; Duruflé, M.

2017-12-01

The temporal covariance between seismic waves measured at two locations on the solar surface is the fundamental observable in time-distance helioseismology. Above the acoustic cut-off frequency ( 5.3 mHz), waves are not trapped in the solar interior and the covariance function can be used to probe the upper atmosphere. We wish to implement appropriate radiative boundary conditions for computing the propagation of high-frequency waves in the solar atmosphere. We consider recently developed and published radiative boundary conditions for atmospheres in which sound-speed is constant and density decreases exponentially with radius. We compute the cross-covariance function using a finite element method in spherical geometry and in the frequency domain. The ratio between first- and second-skip amplitudes in the time-distance diagram is used as a diagnostic to compare boundary conditions and to compare with observations. We find that a boundary condition applied 500 km above the photosphere and derived under the approximation of small angles of incidence accurately reproduces the "infinite atmosphere" solution for high-frequency waves. When the radiative boundary condition is applied 2 Mm above the photosphere, we find that the choice of atmospheric model affects the time-distance diagram. In particular, the time-distance diagram exhibits double-ridge structure when using a Vernazza Avrett Loeser atmospheric model.

Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects

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

Vigeesh, G.; Steiner, O.; Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de

Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in themore » Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.« less

Space astronomy and upper atmospheric sounding

NASA Technical Reports Server (NTRS)

Friedman, H.

1971-01-01

The discoveries and activities of the Space Science Program are reported. Results of studies are presented for the following areas: gamma and x-ray astronomy, optical geophysics and solar wind, infrared astronomy, radio astronomy, and rocket spectroscopy. Lists of publications, talks, and conferences are included.

Statistical Similarities Between WSA-ENLIL+Cone Model and MAVEN in Situ Observations From November 2014 to March 2016

NASA Astrophysics Data System (ADS)

Lentz, C. L.; Baker, D. N.; Jaynes, A. N.; Dewey, R. M.; Lee, C. O.; Halekas, J. S.; Brain, D. A.

2018-02-01

Normal solar wind flows and intense solar transient events interact directly with the upper Martian atmosphere due to the absence of an intrinsic global planetary magnetic field. Since the launch of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, there are now new means to directly observe solar wind parameters at the planet's orbital location for limited time spans. Due to MAVEN's highly elliptical orbit, in situ measurements cannot be taken while MAVEN is inside Mars' magnetosheath. To model solar wind conditions during these atmospheric and magnetospheric passages, this research project utilized the solar wind forecasting capabilities of the WSA-ENLIL+Cone model. The model was used to simulate solar wind parameters that included magnetic field magnitude, plasma particle density, dynamic pressure, proton temperature, and velocity during a four Carrington rotation-long segment. An additional simulation that lasted 18 Carrington rotations was then conducted. The precision of each simulation was examined for intervals when MAVEN was in the upstream solar wind, that is, with no exospheric or magnetospheric phenomena altering in situ measurements. It was determined that generalized, extensive simulations have comparable prediction capabilities as shorter, more comprehensive simulations. Generally, this study aimed to quantify the loss of detail in long-term simulations and to determine if extended simulations can provide accurate, continuous upstream solar wind conditions when there is a lack of in situ measurements.

Hot hydrogen and oxygen atoms in the upper atmospheres of Venus and Mars

NASA Astrophysics Data System (ADS)

Nagy, A. F.; Kim, J.; Cravens, T. E.

1990-04-01

Optical observations of hot atoms in the atmospheres of Venus and Mars are briefly reviewed. A summary of hot hydrogen and oxygen production and loss processes is given. Results of some recent model calculations as well as a number of new results of the hot hydrogen and oxygen populations are presented and their implication in terms of solar wind interaction processes is discussed.

The ATLAS-1 Shuttle mission

NASA Technical Reports Server (NTRS)

Torr, Marsha R.; Sullivan, Kathryn D.

1992-01-01

The Atmospheric Laboratory for Applications and Science (ATLAS-1) encompasses instruments which will be useful in determining long-term solar variability as well as in forging links to the measurements obtained by other spacecraft for the perturbed middle and upper atmosphere. The simultaneous measurements that will be conducted by ATLAS-1 of stratospheric concentrations of ozone, chlorine monoxide and water vapor, at relatively high latitudes during the northern spring, will be especially timely.

VANDENBERG AIR FORCE BASE, CALIF. - With its cover removed, the SciSat-1 spacecraft is rotated. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-29

VANDENBERG AIR FORCE BASE, CALIF. - With its cover removed, the SciSat-1 spacecraft is rotated. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

Temporal and spatial distribution of metallic species in the upper atmosphere

NASA Astrophysics Data System (ADS)

Correira, John Thomas

2009-06-01

Every day the Earth is bombarded by approximately 100 tons of meteoric material. Much of this material is completely ablated on atmospheric entry, resulting in a layer of atomic metals in the upper atmosphere between 70 km - 150 km. These neutral atoms are ionized by solar radiation and charge exchange. Metal ions have a long lifetime against recombination loss, allowing them to be redistributed globally by electromagnetic forces, especially when lifted to altitudes >150 km. UV radiances from the Global Ozone Monitoring Experiment (GOME) spectrometer are used to determine long-term dayside variations of the total vertical column density below 795 km of the meteoric metal species Mg and Mg + in the upper atmosphere. A retrieval algorithm developed to determine magnesium column densities was applied to all available data from the years 1996-2001. Long term results show middle latitude dayside Mg + peaks in vertical content during the summer, while neutral Mg demonstrates a much more subtle maximum in summer. Atmospheric metal concentrations do not correlate strongly solar activity. An analysis of spatial variations shows geospatial distributions are patchy, with local regions of increased column density. To study short term variations and the role of meteor showers a time dependent mass flux rate is calculated using published estimates of meteor stream mass densities and activity profiles. An average daily mass flux rate is also calculated and used as a baseline against which shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal column densities. There appears to be little correlation between modeled meteor shower mass flux rates and changes in the observed neutral magnesium and Mg + metal column densities.

Observations of Space Weather and Space Climate Over the Past 15 Years From SABER (And Longer!)

NASA Technical Reports Server (NTRS)

Mlynczak, Marty; Hunt, Linda; Russell, James M., III

2016-01-01

The global infrared (IR) energy budget of the thermosphere has been reconstructed back 70 years (to 1947). IR cooling, integrated over a solar cycle, is relatively constant over the 5 complete cycles (19 -23) studied. Result implies that solar energy (particles and photons) has similar, small (< 7%) variation from one cycle to next. From Earth's upper atmosphere perspective, solar cycles are really more similar than different, over their length. No consistent relationship between peak of IR cooling and sunspot number peak. Results submitted to GRL 8/2016.

Solar-Terrestrial Physics in the 1990s: Key Science Objectives for the IACG Mission Set

NASA Technical Reports Server (NTRS)

1991-01-01

The International Solar-Terrestrial Physics (ISTP) program is an internationally coordinated multi-spacecraft mission that will study the production of the supersonic magnetized solar wind, its interaction with the Earth's magnetosphere, and the resulting transport of plasma, momentum and energy through the magnetosphere and into the ionosphere and upper atmosphere. The mission will involve l4spacecraft to be launched between 1992 and 1996, along with complementary ground-based observations and theoretical programs. A list of the spacecraft, their nominal orbits, and responsible agencies is shown.

Errors in the determination of the solar constant by the Langley method due to the presence of volcanic aerosol

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

Schotland, R.M.; Hartman, J.E.

1989-02-01

The accuracy in the determination of the solar constant by means of the Langley method is strongly influenced by the spatial inhomogeneities of the atmospheric aerosol. Volcanos frequently inject aerosol into the upper troposphere and lower stratosphere. This paper evaluates the solar constant error that would occur if observations had been taken throughout the plume of El Chichon observed by NASA aircraft in the fall of 1982 and the spring of 1983. A lidar method is suggested to minimize this error. 15 refs.

Variability of Lyman-alpha emission from Jupiter

NASA Technical Reports Server (NTRS)

1979-01-01

The Jovian Lyman-alpha emission line was again observed in 1978 using the high resolution spectrometer on the Copernicus satellite. In intensity of 8.4+3.0 kilo Rayleighs was measured. This value represents a significant increase in intensity over previous (1976) Copernicus observations, but is lower than the recent (1979) values obtained by Voyager I and IUE. The increase in intensity was accompanied by a significant increase in line width, giving strong support to the theory that the emission results from resonant scattering of the solar Ly-alpha line by H atoms in the upper Jovian atmosphere. The strength of Jovian Ly-alpha emission correlates well with the level of solar activity. The solar extreme ultraviolet radiation varies with the solar cycle. This radiation causes the dissociation of H2 and CH4 into H atoms in the Jovian atmosphere. Therefore, in times of high solar activity, the H column density will increase, causing the observed stronger Jovian Ly-alpha emission.

Variability of Lyman-alpha emission from Jupiter

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

Cochran, W.D.; Barker, E.S.

1979-12-01

The Jovian L..cap alpha.. emission line was reobserved in 1978 March using the high-resolution spectrometer of the Copernicus satellite. An intensity of 8.3 +- 2.9 kilorayleighs was measured. This value represents a significant increase in intensity over previous (1976) Copernicus observations, but is lower than the recent (1979) values obtained by Voyager 1 and IUE. The increase in intensity has been accompanied by a significant increase in line width givin strong support to the theory that the emission results from resonant scattering of the solar L..cap alpha.. line by H atoms in the upper Jovian atmosphere. The strength of Jovianmore » L..cap alpha.. emission correlates well with the level of solar activity. The solar extreme ultraviolet radiation varies with the solar cycle. This radiation causes the dissociation of H/sub 2/ and CH/sub 4/ into H atoms in the Jovian atmosphere. Therefore, in times of high solar activity, the H column density will increase, causing the observed stronger Jovian L..cap alpha.. emission.« less

Asymmetries in ozone depressions between the polar stratospheres following a solar proton event

NASA Technical Reports Server (NTRS)

Maeda, K.; Heath, D. F.

1978-01-01

Ozone depletions in the polar stratosphere during the energetic solar proton event on 4 August 1972 were observed by the backscattered ultraviolet (BUV) experiments on the Nimbus 4 satellite. The observed ozone contents, the ozone depressions and their temporal variations above the 4 mb level exhibited distinct asymmetries between the northern and southern hemispheres. Since the ozone destroying solar particles precipitate rather symmetrically into the two polar atmospheres, due to the geomagnetic dipole field, it is suggested that these asymmetries may be explained in terms of the differences in dynamics between the summer and the winter polar atmospheres. In the summer (northern) hemisphere, the stratospheric and mesospheric ozone depletion and recovery are smooth functions of time due to the preponderance of undistributed orderly flow in this region. On the other hand, the temporal variation of the upper stratospheric ozone in the winter polar atmosphere (southern hemisphere) exhibits large amplitude irregularities. These characteristic differences between the two polar atmospheres are also evident in the vertical distributions of temperatures and winds observed by balloons and rocket soundings.

MAVEN Upstream Observations of the Cycle 24 Space Weather Conditions at Mars

NASA Astrophysics Data System (ADS)

Lee, C. O.; Hara, T.; Halekas, J. S.; Thiemann, E.; Curry, S.; Lillis, R. J.; Larson, D. E.; Espley, J. R.; Gruesbeck, J.; Eparvier, F. G.; Li, Y.; Jian, L.; Luhmann, J. G.; Jakosky, B. M.

2016-12-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft went into orbit around Mars during the height of the activity phase of Solar Cycle 24. The mission was designed in part to study the response of the upper atmosphere, ionosphere, and magnetosphere of Mars to solar and solar wind inputs. When MAVEN is on the Martian dayside and orbiting around its apoapsis altitude of 6200 km, the suite of instruments onboard can measure the solar wind plasma (density, velocity), interplanetary magnetic field (magnitude and direction), and particle counts of solar energetic particles (SEPs), as well as the EUV solar irradiance. We will present an overview of the upstream conditions observed to date and highlight a number of Mars-impacting space weather events due to ICMEs and SEPs. We will also present events that are triggered by corotating interaction regions (CIRs), which become more prominent beyond 1 AU and are the dominant heliospheric structures during the declining phase of the solar cycle. As part of the discussion, we will compare and contrast observations from MAVEN and ACE/WIND or STEREO-A during periods when Mars and the 1-AU observer were in solar opposition or nearly aligned along the solar wind Parker spiral.

Upper limits to trace constituents in Jupiter's atmosphere from an analysis of its 5 micrometer spectrum

NASA Technical Reports Server (NTRS)

Treffers, R. R.; Larson, H. P.; Fink, U.; Gautier, T. N.

1978-01-01

A high-resolution spectrum of Jupiter at 5 micrometers recorded at the Kuiper Airborne Observatory is used to determine upper limits to the column density of 19 molecules. The upper limits to the mixing ratios of SiH4, H2S, HCN, and simple hydrocarbons are discussed with respect to current models of Jupiter's atmosphere. These upper limits are compared to expectations based upon the solar abundance of the elements. This analysis permits upper limit measurements (SiH4), or actual detections (GeH4) of molecules with mixing ratios with hydrogen as low as 10 to the minus 9th power. In future observations at 5 micrometers the sensitivity of remote spectroscopic analyses should permit the study of constituents with mixing ratios as low as 10 to the minus 10th power, which would include the hydrides of such elements as Sn and As as well as numerous organic molecules.

The effect of the solar rotational irradiance variation on the middle and upper atmosphere calculated by a three-dimensional chemistry-climate model

NASA Astrophysics Data System (ADS)

Gruzdev, A. N.; Schmidt, H.; Brasseur, G. P.

2009-01-01

This paper analyzes the effects of the solar rotational (27-day) irradiance variations on the chemical composition and temperature of the stratosphere, mesosphere and lower thermosphere as simulated by the three-dimensional chemistry-climate model HAMMONIA. Different methods are used to analyze the model results, including high resolution spectral and cross-spectral techniques. To force the simulations, an idealized irradiance variation with a constant period of 27 days (apparent solar rotation period) and with constant amplitude is used. While the calculated thermal and chemical responses are very distinct and permanent in the upper atmosphere, the responses in the stratosphere and mesosphere vary considerably in time despite the constant forcing. The responses produced by the model exhibit a non-linear behavior: in general, the response sensitivities (not amplitudes) decrease with increasing amplitude of the forcing. In the extratropics the responses are, in general, seasonally dependent with frequently stronger sensitivities in winter than in summer. Amplitude and phase lag of the ozone response in the tropical stratosphere and lower mesosphere are in satisfactory agreement with available observations. The agreement between the calculated and observed temperature response is generally worse than in the case of ozone.

Atmospheric products from the Upper Atmosphere Research Satellite (UARS)

NASA Technical Reports Server (NTRS)

Ahmad, Suraiya P.; Johnson, James E.; Jackman, Charles H.

2003-01-01

This paper provides information on the products available at the NASA Goddard Earth Sciences (GES) Distributed Active Archive Center (DAAC) from the Upper Atmosphere Research Satellite (UARS) mission. The GES DAAC provides measurements from the primary UARS mission, which extended from launch in September 1991 through September 2001. The ten instruments aboard UARS provide measurements of atmospheric trace gas species, dynamical variables, solar irradiance input, and particle energy flux. All standard Level 3 UARS products from all ten instruments are offered free to the public and science user community. The Level 3 data are geophysical parameters, which have been transformed into a common format and equally spaced along the measurement trajectory. The UARS data have been reprocessed several times over the years following improvements to the processing algorithms. The UARS data offered from the GES DAAC are the latest versions of each instrument. The UARS data may be accessed through the GES DAAC website at

Habitats for life in the Venusian Environment? Can the VENUS EXPRESS payload answer?

NASA Astrophysics Data System (ADS)

Muller, C.

2003-04-01

The Venusian conditions are unique in the solar system. Venus abounds in molecules which could feed a life form except that the usual missing factor, energy, is present in excessive amounts from both active geothermic phenomena and from the nearby solar radiation trapped in a dense carbon dioxide atmosphere. Its surface conditions are hotter than the best practiced in hospital sterilisation; volcanism injects highly toxic gases which in the absence of water can accumulate in the atmosphere. Its upper atmosphere lays bare to solar radiation with only carbon dioxide to act as a confirmed EUV filter, so any consideration of life might seem excessive compared to what was known from life on earth before extremophile bacterias were discovered in dark undersea high temperature sulphur rich volcanic vents. However, some regions of the atmosphere might show conditions similar to the earth surface and could be a habitat of earth like microbial life. A synergy between the different atmospheric instruments of the VENUS-Express payload: SPICAM, VIRTIS and PFS can provide the way to probe the actual environmental conditions of this region and to check its capabilities of preserving an extant life or providing nutrients to a new one.

Seasonal variability of the hydrogen exosphere of Mars

NASA Astrophysics Data System (ADS)

Halekas, J. S.

2017-05-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission measures both the upstream solar wind and collisional products from energetic neutral hydrogen atoms that precipitate into the upper atmosphere after their initial formation by charge exchange with exospheric hydrogen. By computing the ratio between the densities of these populations, we derive a robust measurement of the column density of exospheric hydrogen upstream of the Martian bow shock. By comparing with Chamberlain-type model exospheres, we place new constraints on the structure and escape rates of exospheric hydrogen, derived from observations sensitive to a different and potentially complementary column from most scattered sunlight observations. Our observations provide quantitative estimates of the hydrogen exosphere with nearly complete temporal coverage, revealing order of magnitude seasonal changes in column density and a peak slightly after perihelion, approximately at southern summer solstice. The timing of this peak suggests either a lag in the response of the Martian atmosphere to solar inputs or a seasonal effect driven by lower atmosphere dynamics. The high degree of seasonal variability implied by our observations suggests that the Martian atmosphere and the thermal escape of light elements depend sensitively on solar inputs.

Polarimetry Of Planetary Atmospheres: From The Solar System Gas Giants To Extrasolar Planets

NASA Astrophysics Data System (ADS)

Buenzli, Esther; Bazzon, A.; Schmid, H. M.

2011-09-01

The polarization of light reflected from a planet provides unique information on the atmosphere structure and scattering properties of particles in the upper atmosphere. The solar system planets show a large variety of atmospheric polarization properties, from the thick, highly polarizing haze on Titan and the poles of Jupiter, Rayleigh scattering by molecules on Uranus and Neptune, to clouds in the equatorial region of Jupiter or on Venus. Polarimetry is also a promising differential technique to search for and characterize extra-solar planets, e.g. with the future VLT planet finder instrument SPHERE. For the preparation of the SPHERE planet search program we have made a suite of polarimetric observations and models for the solar system gas giants. The phase angles for the outer planets are small for Earth bound observations and the integrated polarization is essentially zero due to the symmetric backscattering situation. However, a second order scattering effect produces a measurable limb polarization for resolved planetary disks. We have made a detailed model for the spectropolarimetric signal of the limb polarization of Uranus between 520 and 935 nm to derive scattering properties of haze and cloud particles and to predict the polarization signal from an extra-solar point of view. We are also investigating imaging polarimetry of the thick haze layers on Titan and the poles of Jupiter. Additionally, we have calculated a large grid of intensity and polarization phase curves for simpler atmosphere models of extrasolar planets.

Concentrations of carbonyl sulfide and hydrogen cyanide in the free upper troposphere and lower stratosphere deduced from ATMOS/Spacelab 3 infrared solar occultation spectra

NASA Technical Reports Server (NTRS)

Zander, R.; Rinsland, C. P.; Russell, J. M., III; Farmer, C. B.; Norton, R. H.

1988-01-01

This paper presents the results on the volume mixing ratio profiles of carbonyl sulfide and hydrogen cyanide, deduced from the spectroscopic analysis of IR solar absorption spectra obtained in the occultation mode with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during its mission aboard Spacelab 3. A comparison of the ATMOS measurements for both northern and southern latitudes with previous field investigations at low midlatitudes shows a relatively good agreement. Southern Hemisphere volume mixing ratio profiles for both molecules were obtained for the first time, as were the profiles for the Northern Hemisphere covering the upper troposphere and the lower stratosphere simultaneously.

Ground-Level Ozone Following Astrophysical Ionizing Radiation Events: An Additional Biological Hazard?

PubMed

Thomas, Brian C; Goracke, Byron D

2016-01-01

Astrophysical ionizing radiation events such as supernovae, gamma-ray bursts, and solar proton events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in solar UV radiation at Earth's surface and in the upper levels of the ocean. Other work has also considered the potential impact of nitric acid rainout, concluding that no significant threat is likely. Not yet studied to date is the potential impact of ozone produced in the lower atmosphere following an ionizing radiation event. Ozone is a known irritant to organisms on land and in water and therefore may be a significant additional hazard. Using previously completed atmospheric chemistry modeling, we examined the amount of ozone produced in the lower atmosphere for the case of a gamma-ray burst and found that the values are too small to pose a significant additional threat to the biosphere. These results may be extended to other ionizing radiation events, including supernovae and extreme solar proton events.

A Future Mars Environment for Science and Exploration

NASA Technical Reports Server (NTRS)

Green, J. L.; Hollingsworth, J. L.; Kahre, M. A.; Brain, D.; Airapetian, V.; Glocer, A.; Pulkkinen, A.; Dong, C.; Bamford, R.

2017-01-01

Today, Mars is arid and cold with a very thin atmosphere that has significant frozen and underground water resources. The thin atmosphere prevents liquid water from residing permanently on its surface and makes it difficult to land missions since it is not thick enough to completely facilitate a soft landing. In its past, under the influence of a significant greenhouse effect, Mars must have had a significant water ocean covering perhaps 30% of the northern hemisphere. Mars lost its protective magnetosphere and therefore much of its atmosphere around 3 Ga ago, due to the solar wind. The atmospheric loss into the solar wind is somewhat balanced by the outgassing of the Mars interior and crust that contributes to the existing atmosphere leading to a global-mean surface atmosphere of 6 mbar pressure currently. By using our extensive simulation tools and physics capabilities in Space Weather and Mars global climate modeling, we have started to explore the effects on Mars of placing an artificial magnetic dipole field at the Mars L1 Lagrange point putting Mars in a magnetotail. This situation then eliminates many of the solar-wind erosion processes that occur with the planet's ionosphere and upper atmosphere allowing the Martian atmosphere to grow in pressure and bulk temperature over time. Under thicker atmospheres, the global circulation patterns and seasonal changes are much different than at present. An enhanced atmosphere would: allow larger landed mass of equipment to the surface, shield against some cosmic and solar particle radiation, extend the ability for extraction, and provide "open air" greenhouses to exist for plant production, just to name a few. These new conditions on Mars would allow human explorers and researchers to study the planet in much greater detail and enable a truly profound new understanding of the habitability of this planet.

Intensive Titan exploration begins.

PubMed

Mahaffy, Paul R

2005-05-13

The Cassini Orbiter spacecraft first skimmed through the tenuous upper atmosphere of Titan on 26 October 2004. This moon of Saturn is unique in our solar system, with a dense nitrogen atmosphere that is cold enough in places to rain methane, the feedstock for the atmospheric chemistry that produces hydrocarbons, nitrile compounds, and Titan's orange haze. The data returned from this flyby supply new information on the magnetic field and plasma environment around Titan, expose new facets of the dynamics and chemistry of Titan's atmosphere, and provide the first glimpses of what appears to be a complex, fluid-processed, geologically young Titan surface.

Aerosol growth in Titan’s ionosphere

PubMed Central

Lavvas, Panayotis; Yelle, Roger V.; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J.; Wahlund, Jan-Erik; Crary, Frank J.; Snowden, Darci

2013-01-01

Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan’s upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere. PMID:23382231

Aerosol growth in Titan's ionosphere.

PubMed

Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

2013-02-19

Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere.

Seasonal variations of the atmospheric temperature response in mesosphere and lower thermosphere on solar activity

NASA Astrophysics Data System (ADS)

Semenov, A. I.; Shefov, N. N.

2003-04-01

On the basis of the measurement data of temperature by rocket and ground-based spectrophotometric (nightglow emissions of hydroxyl,sodium and atomic oxygen of 557.7 nm) methods obtained during 21 and 22 cycles of solar activity, the distributions with height of mean monthly temperature of an atmosphere for region of altitudes Z from 60 to 100 km have been constructed. The periods of maxima and minima of solar activity (1980 and 1991, F10.7=198 and 208; 1976 and 1986, F10.7=73 and 75) were considered. On the basis of these distributions with height of the seasonal variations of dependence of temperature from solar activity S = deltaT(Z)/deltaF, K/100 sfu have been analyzed. It was revealed, that character of seasonal variations essentially changes with growth of height. Mean annual solar response S at heights lower than 70 km is negative, and at higher heights is positive. This solar response S in mesopause region reaches 3 (sigma=1). Such character of influence of solar activity on temperature of the upper atmosphere is caused by features of mean annual and seasonal variations of its distributions with height. The distributions with height of amplitudes and phases of three harmonics of seasonal variations S are presented. This work was supported by the Grant N 2274 of ISTC.

The Solar Connections Observatory for Planetary Environments (SCOPE):

NASA Astrophysics Data System (ADS)

Oliversen, R.; Harris, W.; Ballester, G.; Bougher, S.; Broadfoot, L.; Combi, M.; Cravens, T.; Gombosi, T.; Herbert, F.; Joseph, C.; Kozyra, J.; Limaye, S.; Morgenthaler, J.; Paxton, L.; Roesler, F.; Sandel, W.; Ben Jaffel, L.

2001-12-01

The NASA Sun-Earth Connection theme roadmap calls for comparative study of how the planets and local interstellar medium (LISM) interact with and respond to changes in the solar wind and UV radiation field. Each planet interaction is unique and defined by solar input and local conditions of magnetic field strength and orientation, rotation rate, heliocentric distance, internal plasma, and ionospheric conductivity and circulation. Because the different elements of the environment respond to external and internal influences that are variable on many temporal and spatial scales, the study of a planetary system requires simultaneous understanding of the solar wind and diagnostics of the sun-planet interaction including auroral intensity and variation, upper atmospheric circulation and composition, and the distribution of neutrals and plasmas near the planet. The Solar Connections Observatory for Planetary Environments (SCOPE) is a mission to study Solar interactions from the level of planetary upper atmospheres to the heliopause. SCOPE consists of a binocular EUV/FUV telescope that provides high spatial resolution imaging, broadband spectro-imaging, and high-resolution H Ly-alpha line spectroscopy between 55-290 nm. SCOPE will study planetary environments as examples of the solar connection and map the distribution of interplanetary H and the interaction of LISM plasma with the solar wind at the heliopause. A key to the SCOPE approach is to include Earth in its research objectives. SCOPE will monitor terrestrial auroral energy deposition and leverage local measurements of the solar wind and propagation models to derive the expected conditions at Superior planets that will be observed in annual opposition campaigns. This will permit direct comparison of planetary and terrestrial responses to the same solar wind stream. Using a combination of observations and MHD models, SCOPE will isolate the different controlling parameters in each planet system and gain insight into the underlying physical processes that define the solar connection.

Upper Atmosphere Research Satellite attitude disturbances during shadow entry and exit

NASA Technical Reports Server (NTRS)

Lambertson, M.; Underwood, S.; Woodruff, C.; Garber, A.

1993-01-01

The Upper Atmosphere Research Satellite (UARS), as with the Landsat-4 and Landsat-5 spacecraft, experiences large attitude disturbances when entering and exiting the Earth's shadow. Previous investigations have provided some evidence linking these disturbances to rapid bending of the solar array but have also raised questions. For example, the magnitudes of the roll attitude disturbances have shown an unmolested asymmetry, and the timing of the disturbances at sunrise appears to disagree with the modeled timing. A better understanding of this phenomenon is important in assessing the implications for UARS science gathering and for future mission design analysis. To this end, UARS attitude, sensor, and actuator data are used to evaluate the disturbances as they vary with solar beta angle and solar array drive angle. The attitude data are examined during specific periods of interest, such as the month in which the solar array was parked in its high-noon position, and are also tracked from the beginning of the mission to determine any trends that may result from changing mass properties due to cryogen boiloff and propellant usage. Attitude rate and torque profiles are derived from inertial reference until data and related to the disturbances seen in the attitude data. The timing of the disturbances with respect to spacecraft sunset and sunrise is characterized to allow event predictions. Stability during the disturbances is discussed in terms of science instrument requirements. Finally, the results are compared with the behavior predicted by models that are based on solar array bending.

Solar cell calibration facility validation of balloon flight data: A comparison of shuttle and balloon flight results

NASA Technical Reports Server (NTRS)

Anspaugh, B. E.; Downing, R. G.; Sidwell, L. B.

1985-01-01

The Solar Cell Calibration Facility (SCCF) experiment was designed and built to evaluate the effect of the Earth's upper atmosphere on the calibration of solar cell standards. During execution of the experiment, a collection of carefully selected solar cells was flown on the shuttle, and reflown on a high-altitude balloon, then their outputs were compared. After correction to standard temperature and intensity values of 28 C and an Earth-Sun distance of 1 AU, the solar cell outputs during the two flights were found to be identical. The conclusion is therefore that the high-altitude balloon flights are very good vehicles for calibrating solar cells for use as space flight reference standards.

Modulation of Cosmic Ray Precipitation Related to Climate

NASA Technical Reports Server (NTRS)

Feynman, J.; Ruzmaikin, A.

1998-01-01

High energy cosmic rays may influence the formation of clouds, and thus can have an impact on weather and climate. Cosmic rays in the solar wind are incident on the magnetosphere boundary and are then transmitted through the magnetosphere and atmosphere to reach the upper troposphere.

KSC-2013-3594

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians prepare to deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

KSC-2013-3592

NASA Image and Video Library

2013-09-16

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, engineers and technicians prepare to deploy the Solar Wind Electron Analyzer boom on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. The analyzer will measure the solar wind and electrons in the ionosphere of the Red Planet. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Kim Shiflett

Critical Evaluation of Chemical Reaction Rates and Collision Cross Sections of Importance in the Earth's Upper Atmosphere and the Atmospheres of Other Planets, Moons, and Comets

NASA Technical Reports Server (NTRS)

Huestis, David L.

2006-01-01

We propose to establish a long-term program of critical evaluation by domain experts of the rates and cross sections for atomic and molecular processes that are needed for understanding and modeling the atmospheres in the solar system. We envision data products resembling those of the JPL/NASA Panel for Data Evaluation and the similar efforts of the international combustion modeling community funded by US DoE and its European counterpart.

Apparatus and method for the horizontal, crucible-free growth of silicon sheet crystals

DOEpatents

Ciszek, Theodore F.

1987-01-01

Apparatus for continuously forming a silicon crystal sheet from a silicon rod in a noncrucible environment. The rod is rotated and fed toward an RF coil in an inert atmosphere so that the upper end of the rod becomes molten and the silicon sheet crystal is pulled therefrom substantially horizontally in a continuous strip. A shorting ring may be provided around the rod to limit the heating to the upper end only. Argon gas can be used to create the inert atmosphere within a suitable closed chamber. By use of this apparatus and method, a substantially defect-free silicon crystal sheet is formed that can be used for microcircuitry chips or solar cells.

The use of the German V-2 in US for upper atmosphere research

NASA Technical Reports Server (NTRS)

Curtis, S. A.

1979-01-01

Early U.S. space experiments involving the liquid propellant German V-2 are discussed. Although the primary objective of the experiments conducted under project Hermes after World War II was initially the development of missile technology, scientific objectives were soon given the priority. The missile was modified for scientific experiments and the payload increased from 6.8% to 47% between 1946 and 1949. Among other instruments, the payload included a cosmic ray telescope, ionosphere transmitter and spectrograph for solar spectral measurements. While the scientific success of the program established a positive public attitude towards space research, the Upper Atmosphere Research Panel, formed to coordinate the project, set a pattern for future scientific advisory bodies.

High resolution solar observations in the context of space weather prediction

NASA Astrophysics Data System (ADS)

Yang, Guo

Space weather has a great impact on the Earth and human life. It is important to study and monitor active regions on the solar surface and ultimately to predict space weather based on the Sun's activity. In this study, a system that uses the full power of speckle masking imaging by parallel processing to obtain high-spatial resolution images of the solar surface in near real-time has been developed and built. The application of this system greatly improves the ability to monitor the evolution of solar active regions and to predict the adverse effects of space weather. The data obtained by this system have also been used to study fine structures on the solar surface and their effects on the upper solar atmosphere. A solar active region has been studied using high resolution data obtained by speckle masking imaging. Evolution of a pore in an active region presented. Formation of a rudimentary penumbra is studied. The effects of the change of the magnetic fields on the upper level atmosphere is discussed. Coronal Mass Ejections (CMEs) have a great impact on space weather. To study the relationship between CMEs and filament disappearance, a list of 431 filament and prominence disappearance events has been compiled. Comparison of this list with CME data obtained by satellite has shown that most filament disappearances seem to have no corresponding CME events. Even for the limb events, only thirty percent of filament disappearances are associated with CMEs. A CME event that was observed on March 20, 2000 has been studied in detail. This event did not show the three-parts structure of typical CMEs. The kinematical and morphological properties of this event were examined.

Societal Impacts of Solar Electromagnetic Radiation

NASA Astrophysics Data System (ADS)

Lean, J. L.

2000-05-01

Changes in solar electromagnetic radiation, which occur continuously and at all wavelengths of the spectrum, can have significant societal impacts on a wide range of time scales. Detection of climate change and ozone depletion requires reliable specification of solar-induced processes that mask or exacerbate anthropogenic effects. Living with, and mitigating, climate change and ozone depletion has significant economic, habitat and political impacts of international extent. As an example, taxes to restrict carbon emission may cause undue economic stress if the role of greenhouse gases in global warming is incorrectly diagnosed. Ignoring solar-induced ozone changes in the next century may lead to incorrect assessment of the success of the Montreal Protocol in protecting the ozone layer by limiting the use of ozone-destroying chlorofluorocarbons. Societal infrastructure depends in many ways on space-based technological assets. Communications and navigation for commerce, industry, science and defense rely on satellite signals transmitted through, and reflected by, electrons in the ionosphere. Electron densities change in response to solar flares, and by orders of magnitude in response to EUV and X-ray flux variations during the Sun's 11-year activity cycle. Spacecraft and space debris experience enhanced drag on their orbits when changing EUV radiation causes upper atmosphere densities to increase. Especially affected are spacecraft and debris in lower altitude orbits, such as Iridium-type communication satellites, and the International Space Station (ISS). Proper specification of solar-induced fluctuations in the neutral upper atmosphere can, for example, aid in tracking the ISS and surrounding space debris, reducing the chance of ISS damage from collisions, and maximizing its operations. Aspects of solar electromagnetic radiation variability will be briefly illustrated on a range of time scales, with specific identification of the societal impacts of different spectral regions.

Chapman Solar Zenith Angle variations at Titan

NASA Astrophysics Data System (ADS)

Royer, Emilie M.; Ajello, Joseph; Holsclaw, Gregory; West, Robert; Esposito, Larry W.; Bradley, Eric Todd

2016-10-01

Solar XUV photons and magnetospheric particles are the two main sources contributing to the airglow in the Titan's upper atmosphere. We are focusing here on the solar XUV photons and how they influence the airglow intensity. The Cassini-UVIS observations analyzed in this study consist each in a partial scan of Titan, while the center of the detector stays approximately at the same location on Titan's disk. We used observations from 2008 to 2012, which allow for a wide range of Solar Zenith Angle (SZA). Spectra from 800 km to 1200 km of altitude have been corrected from the solar spectrum using TIMED/SEE data. We observe that the airglow intensity varies as a function of the SZA and follows a Chapman curve. Three SZA regions are identified: the sunlit region ranging from 0 to 50 degrees. In this region, the intensity of the airglow increases, while the SZA decreases. Between SZA 50 and 100 degrees, the airglow intensity decreases from it maximum to its minimum. In this transition region the upper atmosphere of Titan changes from being totally sunlit to being in the shadow of the moon. For SZA 100 to 180 degrees, we observe a constant airglow intensity close to zero. The behavior of the airglow is also similar to the behavior of the electron density as a function of the SZA as observed by Ågren at al (2009). Both variables exhibit a decrease intensity with increasing SZA. The goal of this study is to understand such correlation. We demonstrate the importance of the solar XUV photons contribution to the Titan airglow and prove that the strongest contribution to the Titan dayglow occurs by solar fluorescence rather than the particle impact that predominates at night.

Disentangling flows in the solar transition region

NASA Astrophysics Data System (ADS)

Zacharias, P.; Hansteen, V. H.; Leenaarts, J.; Carlsson, M.; Gudiksen, B. V.

2018-06-01

Context. The measured average velocities in solar and stellar spectral lines formed at transition region temperatures have been difficult to interpret. The dominant redshifts observed in the lower transition region naturally leads to the question of how the upper layers of the solar (and stellar) atmosphere can be maintained. Likewise, no ready explanation has been made for the average blueshifts often found in upper transition region lines. However, realistic three-dimensional radiation magnetohydrodynamics (3D rMHD) models of the solar atmosphere are able to reproduce the observed dominant line shifts and may thus hold the key to resolve these issues. Aims: These new 3D rMHD simulations aim to shed light on how mass flows between the chromosphere and corona and on how the coronal mass is maintained. These simulations give new insights into the coupling of various atmospheric layers and the origin of Doppler shifts in the solar transition region and corona. Methods: The passive tracer particles, so-called corks, allow the tracking of parcels of plasma over time and thus the study of changes in plasma temperature and velocity not only locally, but also in a co-moving frame. By following the trajectories of the corks, we can investigate mass and energy flows and understand the composition of the observed velocities. Results: Our findings show that most of the transition region mass is cooling. The preponderance of transition region redshifts in the model can be explained by the higher percentage of downflowing mass in the lower and middle transition region. The average upflows in the upper transition region can be explained by a combination of both stronger upflows than downflows and a higher percentage of upflowing mass. The most common combination at lower and middle transition region temperatures are corks that are cooling and traveling downward. For these corks, a strong correlation between the pressure gradient along the magnetic field line and the velocity along the magnetic field line has been observed, indicating a formation mechanism that is related to downward propagating pressure disturbances. Corks at upper transition region temperatures are subject to a rather slow and highly variable but continuous heating process. Conclusions: Corks are shown to be an essential tool in 3D rMHD models in order to study mass and energy flows. We have shown that most transition region plasma is cooling after having been heated slowly to upper transition region temperatures several minutes before. Downward propagating pressure disturbances are identified as one of the main mechanisms responsible for the observed redshifts at transition region temperatures. The movie associated to Fig. 3 is available at http://www.aanda.org

Global structure and composition of the martian atmosphere with SPICAM on Mars express

NASA Astrophysics Data System (ADS)

Bertaux, Jean-Loup; Korablev, O.; Fonteyn, D.; Guibert, S.; Chassefière, E.; Lefèvre, F.; Dimarellis, E.; Dubois, J. P.; Hauchecorne, A.; Cabane, M.; Rannou, P.; Levasseur-Regourd, A. C.; Cernogora, G.; Quémerais, E.; Hermans, C.; Kockarts, G.; Lippens, C.; de Maziere, M.; Moreau, D.; Muller, C.; Neefs, E.; Simon, P. C.; Forget, F.; Hourdin, F.; Talagrand, O.; Moroz, V. I.; Rodin, A.; Sandel, B.; Stern, A.

SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) Light, a light-weight (4.7 kg) UV-IR instrument to be flown on Mars Express orbiter, is dedicated to the study of the atmosphere and ionosphere of Mars. A UV spectrometer (118-320 nm, resolution 0.8 nm) is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation (3.8 kg). It addresses key issues about ozone, its coupling with H2O, aerosols, atmospheric vertical temperature structure and ionospheric studies. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. An IR spectrometer (1.0-1.7 μm, resolution 0.5-1.2 nm) is dedicated primarily to nadir measurements of H2O abundances simultaneously with ozone measured in the UV, and to vertical profiling during solar occultation of H2O, CO2, and aerosols. The SPICAM Light near-IR sensor employs a pioneering technology acousto-optical tunable filter (AOTF), leading to a compact and light design. Overall, SPICAM Light is an ideal candidate for future orbiter studies of Mars, after Mars Express, in order to study the interannual variability of martian atmospheric processes. The potential contribution to a Mars International Reference Atmosphere is clear.

Hemispheric asymmetries in high-latitude ionospheric convection and upper atmosphere neutral wind circulation

NASA Astrophysics Data System (ADS)

Foerster, M.; Cnossen, I.; Haaland, S.

2015-12-01

Recent observations have shown that the ionospheric/thermospheric response to solar wind and IMF dependent processes in the magnetosphere can be very dissimilar in the Northern and Southern polar regions. We present statistical studies of both the high-latitude ionospheric convection and the upper thermospheric circulation patterns obtained over almost a full solar cycle during the first decade of this century by measurements of the electron drift instrument (EDI) on board the Cluster satellites and by the accelerometer on board the CHAMP spacecraft, respectively. The asymmetries are attributed to the non-dipolar portions of the Earth's magnetic field that constitute hemispheric differences in magnetic flux densities, different offsets of the invariant geomagnetic poles, and generally in different field configurations of both hemispheres. Seasonal and solar cycle effects of the asymmetries are considered and first trials to explain the effects by numerical modeling are presented.

The Thermospheric Semiannual Density Response to Solar EUV Heating

DTIC Science & Technology

2008-01-01

Keystone, CO. Cook, G.E., 1969. The semi-annual variation in the upper atmosphere: a review. Annales de Geophysique 25, 451. Jacchia, L.G., 1966. Density...variations in the heterosphere. Annales de Geophysique 22, 75. Jacchia, L.G., 1971a. Semiannual variation in the heterosphere: a reappraisal. Journal

Dynamics Explorer twin spacecraft under evaluation tests

NASA Technical Reports Server (NTRS)

Redmond, C.

1981-01-01

The Dynamics Explorer A and B satellites designed to explore the interactive processes occuring between the magnetosphere and Earth's ionosphere, upper atmosphere, and plasmasphere are described. Effects of these interactions, satellite orbits, data collecting antennas, solar power systems, axes, configurations, and Earth based command, control and data display systems are mentioned.

Summary of spacecraft technology, systems reliability, and tracking data acquisition

NASA Technical Reports Server (NTRS)

1973-01-01

Goddard activities are reported for 1973. An eight-year flight schedule for projected space missions is presented. Data acquired by spacecraft in the following disciplines are described: stellar ultraviolet, stellar X-rays, stellar gamma rays, solar radiation, radio astronomy, particles/fields, magnetosphere, aurora, and the upper atmosphere.

The Variability of Atmospheric Deuterium Brightness at Mars: Evidence for Seasonal Dependence

NASA Astrophysics Data System (ADS)

Mayyasi, Majd; Clarke, John; Bhattacharyya, Dolon; Deighan, Justin; Jain, Sonal; Chaffin, Michael; Thiemann, Edward; Schneider, Nick; Jakosky, Bruce

2017-10-01

The enhanced ratio of deuterium to hydrogen on Mars has been widely interpreted as indicating the loss of a large column of water into space, and the hydrogen content of the upper atmosphere is now known to be highly variable. The variation in the properties of both deuterium and hydrogen in the upper atmosphere of Mars is indicative of the dynamical processes that produce these species and propagate them to altitudes where they can escape the planet. Understanding the seasonal variability of D is key to understanding the variability of the escape rate of water from Mars. Data from a 15 month observing campaign, made by the Mars Atmosphere and Volatile Evolution Imaging Ultraviolet Spectrograph high-resolution echelle channel, are used to determine the brightness of deuterium as observed at the limb of Mars. The D emission is highly variable, with a peak in brightness just after southern summer solstice. The trends of D brightness are examined against extrinsic as well as intrinsic sources. It is found that the fluctuations in deuterium brightness in the upper atmosphere of Mars (up to 400 km), corrected for periodic solar variations, vary on timescales that are similar to those of water vapor fluctuations lower in the atmosphere (20-80 km). The observed variability in deuterium may be attributed to seasonal factors such as regional dust storm activity and subsequent circulation lower in the atmosphere.

The composition of Saturn's atmosphere at northern temperate latitudes from Voyager IRIS spectra - NH3, PH3, C2H2, C2H6, CH3D, CH4, and the Saturnian D/H isotopic ratio

NASA Technical Reports Server (NTRS)

Courtin, R.; Gautier, D.; Marten, A.; Bezard, B.; Hanel, R.

1984-01-01

The vertical distributions and mixing ratios of minor constituents in the northern hemisphere of Saturn are investigated. Results are obtained for NH3, PH3, C2H2, C2H6, CH3D, and CH4; the D/H ratio is obtained from the CH4 and CH3D abundances. The NH3 mixing ratio in the upper atmosphere is found to be compatible with the saturated partial pressure. The inferred PH3/H2 ratio of 1.4 + or - 0.8 x 10 to the -6th is higher than the value derived from the solar P/H ratio. The stratospheric C2H2/H2 and C2H6/H2 ratios are, respectively, 2.1 + or - 1.4 x 10 to the -7th and 3.0 + or - 1.1 x 10 to the -6th; the latter decreases sharply below the 20-50 mbar level. The results for CH3D/H2 and CH4/H2 imply an enrichment of Saturn's upper atmosphere in carbon by a factor of at least three over the solar abundance. The interpretation of two NH3 lines in the five-micron window suggests a NH3/H2 ratio at the two bar level below the solar value.

Martian Ionospheric Observation and Modeling

NASA Astrophysics Data System (ADS)

González-Galindo, Francisco

2018-02-01

The Martian ionosphere is a plasma embedded within the neutral upper atmosphere of the planet. Its main source is the ionization of the CO2-dominated Martian mesosphere and thermosphere by the energetic EUV solar radiation. The ionosphere of Mars is subject to an important variability induced by changes in its forcing mechanisms (e.g., the UV solar flux) and by variations in the neutral atmosphere (e.g., the presence of global dust storms, atmospheric waves and tides, changes in atmospheric composition, etc.). Its vertical structure is dominated by a maximum in the electron concentration placed at about 120–140 km of altitude, coincident with the peak of the ionization rate. Below, a secondary peak produced by solar X-rays and photoelectron-impact ionization is observed. A sporadic third layer, possibly of meteoric origin, has been also detected below. The most abundant ion in the Martian ionosphere is O2+, although O+ can become more abundant in the upper ionospheric layers. While below about 180–200 km the Martian ionosphere is dominated by photochemical processes, above those altitudes the dynamics of the plasma become more important. The ionosphere is also an important source of escaping particles via processes such as dissociative recombination of ions or ion pickup. So, characterization of the ionosphere provides or can provide information about such disparate systems and processes as the solar radiation getting to the planet, the neutral atmosphere, the meteoric influx, the atmospheric escape to space, or the interaction of the planet with the solar wind. It is thus not surprising that the interest about this region dates from the beginning of the space era. From the first measurements provided by the Mariner 4 mission in the 1960s to the contemporaneous observations, still ongoing, by the Mars Express and MAVEN orbiters, our current knowledge of this atmospheric region is the consequence of the accumulation of more than 50 years of discontinuous measurements by different space missions. Numerical simulations by computational models able to simulate the processes that shape the ionosphere have also been commonly employed to obtain information about this region, to provide an interpretation of the observations and to fill their gaps. As a result, the Martian ionosphere is today the best known one after that of the Earth. However, there are still areas for which our knowledge is far from being complete. Examples are the details and balance of the mechanisms populating the nightside ionosphere, or a good understanding of the meteoric ionospheric layer and its variability.

Chromospheric heating

NASA Technical Reports Server (NTRS)

Kalkofen, Wolfgang

1989-01-01

The solar chromosphere is identified with the atmosphere inside magnetic flux tubes. Between the temperature minimum and the 7000 K level, the chromosphere in the bright points of the quiet sun is heated by large-amplitude, long-period, compressive waves with periods mainly between 2 and 4 minutes. These waves do not observe the cutoff condition according to which acoustic waves with periods longer than 3 minutes do not propagate vertically in the upper solar photosphere. It is concluded that the long-period waves probably supply all the energy required for the heating of the bright points in the quiet solar chromosphere.

Short- and Medium-term Atmospheric Effects of Very Large Solar Proton Events

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Fleming, Eric L.; Labow, Gordon J.; Randall, Cora E.; Lopez-Puertas, Manuel; Funke, Bernd

2007-01-01

Long-term variations in ozone have been caused by both natural and humankind related processes. In particular, the humankind or anthropogenic influence on ozone from chlorofluorocarbons and halons (chlorine and bromine) has led to international regulations greatly limiting the release of these substances. These anthropogenic effects on ozone are most important in polar regions and have been significant since the 1970s. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the short- and medium-term (days to a few months) influences of solar proton events between 1963 and 2005 on stratospheric ozone. The four largest events in the past 45 years (August 1972; October 1989; July 2000; and October-November 2003) caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen- containing compounds, which led to the polar ozone destruction. The hydrogen-containing compounds have very short lifetimes and lasted for only a few days (typically the duration of the solar proton event). On the other hand, the nitrogen-containing compounds lasted much longer, especially in the Winter. The nitrogen oxides were predicted to increase substantially due to these solar events and led to mid- to upper polar stratospheric ozone decreases of over 20%. These WACCM results generally agreed with satellite measurements. Both WACCM and measurements showed enhancements of nitric acid, dinitrogen pentoxide, and chlorine nitrate, which were indirectly caused by these solar events. Solar proton events were shown to cause a significant change in the polar stratosphere and need to be considered in understanding variations during years of strong solar activity.

Design and performance of the halogen occultation experiment (HALOE) remote sensor

NASA Technical Reports Server (NTRS)

Baker, R. L.; Mauldin, L. E., III; Russell, J. M., III

1986-01-01

HALOE is an optical remote sensor that measures extinction of solar radiation caused by the earth's atmosphere in eight channels, ranging in wavelength from 2.5 to 10.1 microns. These measurements, which occur twice each satellite orbit during solar occultation, are inverted to yield vertical distributions of middle atmosphere ozone (O3), water vapor, nitrogen dioxide, nitric oxide, hydrogen fluoride, hydrogen chloride, and methane. A channel located in the 2.7 region is used to infer the tangent point pressure by measuring carbon dioxide absorption. The HALOE instrument consists of a two-axis gimbal system, telescope, spectral discrimination optics and a 12-bit data system. The gimbal system tracks the solar radiometric centroid in the azimuthal plane and tracks the solar limb in the elevation plane, placing the instrument's instantaneous field-of-view 4 arcmin down from the solar top edge. The instrument gathers data for tangent altitudes ranging from 150 km to the earth's horizon. Prior to an orbital sunset and after an orbital sunrise, HALOE automatically performs calibration sequences to enhance data interpretation. The instrument is presently being tested at the NASA Langley Research Center in preparation for launch on the Upper Atmosphere Research Satellite near the end of this decade. This paper describes the instrumenmt design, operation, and functional performance.

Solar total and spectral irradiance reconstruction over last 9000 years

NASA Astrophysics Data System (ADS)

Wu, Chi-Ju; Usoskin, Ilya; Krivova, Natalie; Solanki, Sami K.

2016-07-01

Although the mechanisms of solar influence on Earth climate system are not yet fully understood, solar total and spectral irradiance are considered to be among the main determinants. Solar total irradiance is the total flux of solar radiative energy entering Earth's climate system, whereas the spectral irradiance describes this energy is distributed over the spectrum. Solar irradiance in the UV band is of special importance since it governs chemical processes in the middle and upper atmosphere. On timescales of the 11-year solar cycle and shorter, solar irradiance is measured by space-based instruments while models are needed to reconstruct solar irradiance on longer timescale. The SATIRE-M model (Spectral And Total Irradiance Reconstruction over millennia) is employed in this study to reconstruct solar irradiance from decadal radionuclide isotope data such as 14C and 10Be stored in tree rings and ice cores, respectively. A reconstruction over the last 9000 years will be presented.

Solar Total and Spectral Irradiance Reconstruction over Last 9000 Years

NASA Astrophysics Data System (ADS)

Wu, C. J.; Krivova, N.; Solanki, S. K.; Usoskin, I. G.

2016-12-01

Although the mechanisms of solar influence on Earth climate system are not yet fully understood, solar total and spectral irradiance are considered to be among the main determinants. Solar total irradiance is the total flux of solar radiative energy entering Earth's climate system, whereas the spectral irradiance describes this energy is distributed over the spectrum. Solar irradiance in the UV band is of special importance since it governs chemical processes in the middle and upper atmosphere. On timescales of the 11-year solar cycle and shorter, solar irradiance is measured by space-based instruments while models are needed to reconstruct solar irradiance on longer timescale. The SATIRE-M model (Spectral And Total Irradiance Reconstruction over millennia) is employed in this study to reconstruct solar irradiance from decadal radionuclide isotope data such as 14C and 10Be stored in tree rings and ice cores, respectively. A reconstruction over the last 9000 years will be presented.

VANDENBERG AIR FORCE BASE, CALIF.- At Vandenberg Air Force Base, Calif., spacecraft functional testing is underway on the SciSat-1. The solar arrays are being attached and the communications systems are also being checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-12

VANDENBERG AIR FORCE BASE, CALIF.- At Vandenberg Air Force Base, Calif., spacecraft functional testing is underway on the SciSat-1. The solar arrays are being attached and the communications systems are also being checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

VANDENBERG AIR FORCE BASE, CALIF. - At Vandenberg Air Force Base, Calif. a covered SciSat-1 spacecraft is lifted onto a rotation stand. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-29

VANDENBERG AIR FORCE BASE, CALIF. - At Vandenberg Air Force Base, Calif. a covered SciSat-1 spacecraft is lifted onto a rotation stand. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

VANDENBERG AIR FORCE BASE, CALIF.- The covered SciSat-1 spacecraft is lowered onto a test stand at Vandenberg Air Force Base, Calif., for functional testing. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-29

VANDENBERG AIR FORCE BASE, CALIF.- The covered SciSat-1 spacecraft is lowered onto a test stand at Vandenberg Air Force Base, Calif., for functional testing. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

VANDENBERG AIR FORCE BASE, CALIF.- A covered SciSat-1 spacecraft sits on a test stand at Vandenberg Air Force Base, Calif. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

NASA Image and Video Library

2003-07-29

VANDENBERG AIR FORCE BASE, CALIF.- A covered SciSat-1 spacecraft sits on a test stand at Vandenberg Air Force Base, Calif. The solar arrays will be attached and the communications systems checked out. The SciSat-1 weighs approximately 330 pounds and after launch will be placed in a 400-mile-high polar orbit to investigate processes that control the distribution of ozone in the upper atmosphere. The data from the satellite will provide Canadian and international scientists with improved measurements relating to global ozone processes and help policymakers assess existing environmental policy and develop protective measures for improving the health of our atmosphere, preventing further ozone depletion. The mission is designed to last two years.

The Hazards of Our Star

NASA Technical Reports Server (NTRS)

Klimchuk, James A.

2011-01-01

The Sun's magnetic field permeates its atmosphere - ranging from the solar photosphere (the visible "surface") to the corona above. Think of this field as a collection of invisible rubber bands that are slowly stretched and twisted until they eventually reach a breaking point, When the field breaks, it releases a small amount of energy, known as a nanoflare. Millions of nanoflares occur every second, and the combined effect heats the solar corona to more than 1 million kelvins, hundreds of times hotter than the photosphere. The super-heated gas emits X-ray and ultraviolet radiation; Earth's upper atmosphere absorbs it, which changes our atmosphere's properties. This can disrupt communication, navigation, and surveillance systems, and also alter the orbits of satellites. On much larger scales, huge sections of the corona explosively erupt in coronal mass ejections (CMEs) and solar flares. CMEs directed toward Earth cause geomagnetic storms, which can wreck havoc on electrical power grids and produce widespread blackouts. Highly energetic particles can damage or even disable critical spacecraft components. Intense radiation from flares has the same effects as nanoflares, but to a greater degree. The need to understand how solar phenomena impact Earth has led to an important science field called space weather.

Energetic Metastable Oxygen and Nitrogen Atoms in the Terrestrial Atmosphere

NASA Technical Reports Server (NTRS)

Kharchenko, Vasili; Dalgarno, A.

2005-01-01

This report summarizes our research performed under NASA Grant NAG5-11857. The three-year grant have been supported by the Geospace Sciences SR&T program. We have investigated the energetic metastable oxygen and nitrogen atoms in the terrestrial stratosphere, mesosphere and thermosphere. Hot atoms in the atmosphere are produced by solar radiation, the solar wind and various ionic reactions. Nascent hot atoms arise in ground and excited electronic states, and their translational energies are larger by two - three orders of magnitude than the thermal energies of the ambient gas. The relaxation kinetics of hot atoms determines the rate of atmospheric heating, the intensities of aeronomic reactions, and the rate of atom escape from the planet. Modeling of the non-Maxwellian energy distributions of metastable oxygen and nitrogen atoms have been focused on the determination of their impact on the energetics and chemistry of the terrestrial atmosphere between 25 and 250 km . At this altitudes, we have calculated the energy distribution functions of metastable O and N atoms and computed non-equilibrium rates of important aeronomic reactions, such as destruction of the water molecules by O(1D) atoms and production of highly excited nitric oxide molecules. In the upper atmosphere, the metastable O(lD) and N(2D) play important role in formation of the upward atomic fluxes. We have computed the upward fluxes of the metastable and ground state oxygen atoms in the upper atmosphere above 250 km. The accurate distributions of the metastable atoms have been evaluated for the day and night-time conditions.

Consistency Between SC#21REF Solar XUV Energy Input and the 1973 Pioneer 10 Observations of the Jovian Photoelectron Excited H2 Airglow

NASA Technical Reports Server (NTRS)

Gangopadhyay, P.; Ogawa, H. S.; Judge, D. L.

1988-01-01

It has been suggested in the literature that the F74113 solar spectrum for the solar minimum condition needs to be modified to explain the production of photoelectrons in the Earth's atmosphere. We have studied here the effect of another solar minimum spectrum, SC#21REF, on the Jovian upper atmosphere emissions and we have compared the predicted photoelectron excited H2 airglow with the 1973 Pioneer 10 observations, analyzed according to the methodology of Shemansky and Judge (1988). In this model calculation we find that in 1973, the Jovian H2 band emissions can be accounted for almost entirely by photoelectron excitation, if the preflight calibration of the Pioneer 10 ultraviolet photometer is adopted. If the SC#21REF flux shortward of 250 A is multiplied by 2 as proposed by Richards and Torr (1988) then the Pioneer 10 calibration and/or the airglow model used must be modified in order to have a self consistent set of observations.

The Mg II h and k lines. II - Comparison with synthesized profiles and Ca II K. [solar spectra

NASA Technical Reports Server (NTRS)

Ayres, T. R.; Linsky, J. L.

1976-01-01

Measured high-dispersion center and limb profiles of the solar Mg II h and k resonance lines are compared with synthetic spectra computed with a partial-redistribution formalism and based on several upper-photosphere and lower-chromosphere temperature distributions. Profiles of the analogously formed Ca II K resonance line are also synthesized for the same atmospheric models. The spectrum-synthesis approach is outlined, and the collisional and fixed radiative rates appropriate to the adopted model atoms and solar atmosphere are discussed. It is found that the HSRA and VAL models predict systematically lower intensities in the h, k, and K inner wings than observed and that models with a somewhat higher minimum temperature (about 4450 K) can reproduce the measured inner wings and limb darkening. A 'Ca II' solar model with a minimum temperature of 4450 K is proposed as an alternative to the class of models based on continuum observations.

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.

Polarized Kink Waves in Magnetic Elements: Evidence for Chromospheric Helical Waves

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

Stangalini, M.; Giannattasio, F.; Erdélyi, R.

In recent years, new high spatial resolution observations of the Sun's atmosphere have revealed the presence of a plethora of small-scale magnetic elements down to the resolution limit of the current cohort of solar telescopes (∼100–120 km on the solar photosphere). These small magnetic field concentrations, due to the granular buffeting, can support and guide several magnetohydrodynamic wave modes that would eventually contribute to the energy budget of the upper layers of the atmosphere. In this work, exploiting the high spatial and temporal resolution chromospheric data acquired with the Swedish 1 m Solar Telescope, and applying the empirical mode decompositionmore » technique to the tracking of the solar magnetic features, we analyze the perturbations of the horizontal velocity vector of a set of chromospheric magnetic elements. We find observational evidence that suggests a phase relation between the two components of the velocity vector itself, resulting in its helical motion.« less

The Solar Wind Ion Analyzer for MAVEN

NASA Astrophysics Data System (ADS)

Halekas, J. S.; Taylor, E. R.; Dalton, G.; Johnson, G.; Curtis, D. W.; McFadden, J. P.; Mitchell, D. L.; Lin, R. P.; Jakosky, B. M.

2015-12-01

The Solar Wind Ion Analyzer (SWIA) on the MAVEN mission will measure the solar wind ion flows around Mars, both in the upstream solar wind and in the magneto-sheath and tail regions inside the bow shock. The solar wind flux provides one of the key energy inputs that can drive atmospheric escape from the Martian system, as well as in part controlling the structure of the magnetosphere through which non-thermal ion escape must take place. SWIA measurements contribute to the top level MAVEN goals of characterizing the upper atmosphere and the processes that operate there, and parameterizing the escape of atmospheric gases to extrapolate the total loss to space throughout Mars' history. To accomplish these goals, SWIA utilizes a toroidal energy analyzer with electrostatic deflectors to provide a broad 360∘×90∘ field of view on a 3-axis spacecraft, with a mechanical attenuator to enable a very high dynamic range. SWIA provides high cadence measurements of ion velocity distributions with high energy resolution (14.5 %) and angular resolution (3.75∘×4.5∘ in the sunward direction, 22.5∘×22.5∘ elsewhere), and a broad energy range of 5 eV to 25 keV. Onboard computation of bulk moments and energy spectra enable measurements of the basic properties of the solar wind at 0.25 Hz.

Post sunset behavior of the 6300 A atomic oxygen airglow emission

NASA Technical Reports Server (NTRS)

Smith, R. E.

1976-01-01

A theoretical model of the 6300 A OI airglow emission was developed based on the assumptions that both the charged and neutral portions of the Earth's upper atmosphere are in steady state conditions of diffusive equilibrium. Intensities of 6300 A OI emission line were calculated using electron density true height profiles from a standard C-4 ionosonde and exospheric temperatures derived from Fabry-Perot interferometer measurements of the Doppler broadened 6300 A emission line shape as inputs to the model. Reaction rate coefficient values, production mechanism efficiencies, solar radiation fluxes, absorption cross sections, and models of the neutral atmosphere were varied parametrically to establish a set of acceptable inputs which will consistently predict 6300 A emission intensities that closely agree with intensities observed during the post-sunset twilight period by an airglow observatory consisting of a Fabry-Perot interferometer and a turret photometer. Emission intensities that can only result from the dissociative recombination of molecular oxygen ions were observed during the latter portion of the observational period. Theoretical calculations indicate that contamination of the 6300 A OI emission should be on the order of or less than 3 percent; however, these results are very sensitive to the wavelengths of the individual lines and their intensities relative to the 6300 A OI intensity. This combination of a model atmosphere, production mechanism efficiencies, and quenching coefficient values was used when the dissociative photoexcitation and direct impact excitation processes were contributing to the intensity to establish best estimates of solar radiation fluxes in the Schumann--Runge continuum and associated absorption cross sections. Results show that the Jacchia 1971 model of the upper atmosphere combined with the Ackerman recommended solar radiation fluxes and associated absorption cross sections produces theoretically calculated intensities that more closely agree with the observed intensities than all the other combinations.

Space Science

NASA Image and Video Library

2001-09-30

Absorption of solar energy heats up our planet's surface and atmosphere making life for us possible. But the energy carnot stay bound up in the Earth's environment forever. If it did, the Earth would be as hot as the sun. Instead, as the surface and atmosphere warm, they emit thermal long wave radiation, some of which escapes into space and allows the Earth to cool. This false color image of the Earth was produced by the Clouds and the Earth's Radiant Energy System (CERES) instrument flying aboard NASA's Terra spacecraft. The image shows where more or less heat, in the form of long-wave radiation, is emanating from the top of the Earth's atmosphere. As one can see in the image, the thermal radiation leaving the oceans is fairly uniform. The blue swaths represent thick clouds, the tops of which are so high they are among the coldest places on Earth. In the American Southwest, which can be seen in the upper right hand corner of the globe, there is often little cloud cover to block outgoing radiation and relatively little water to absorb solar energy making the amount of outgoing radiation in this area exceeding that of the oceans. Recently, NASA researchers discovered that incoming solar radiation and outgoing thermal radiation increased in the tropics from the 1980s to the 1990s. They believe the unexpected change has to do with apparent change in circulation patterns around the globe, which effectively reduce the amount of water vapor and cloud cover in the upper reaches of the atmosphere. Without the clouds, more sunlight was allowed to enter the tropical zones and more thermal energy was allowed to leave. The findings may have big implications for climate change and future global warming. (Image courtesy NASA Goddard)

SPARTAN high resolution solar studies

NASA Technical Reports Server (NTRS)

Bruner, Marilyn E.

1993-01-01

This report summarizes the work performed on Contract NAS5-29739, a sub-orbital research program directed toward the study of the geometry of and physical conditions in matter found in the upper layers of the solar atmosphere. The report describes a new sounding rocket payload developed under the contract, presents a guide to the contents of semiannual reports submitted during the contract, discusses the results of the first flight of the payload and the progress on scientific analysis. A bibliography of papers and publications is included.

Understanding and Forecasting Upper Atmosphere Nitric Oxide Through Data Mining Analysis of TIMED/SABER Data

NASA Astrophysics Data System (ADS)

Flynn, S.; Knipp, D. J.; Matsuo, T.; Mlynczak, M. G.; Hunt, L. A.

2017-12-01

Storm time energy input to the upper atmosphere is countered by infrared radiative emissions from nitric oxide (NO). The temporal profile of these energy sources and losses strongly control thermospheric density profiles, which in turn affect the drag experienced by low Earth orbiting satellites. Storm time processes create NO. In some extreme cases an overabundance of NO emissions unexpectedly decreases atmospheric temperature and density to lower than pre-storm values. Quantifying the spatial and temporal variability of the NO emissions using eigenmodes will increase the understanding of how upper atmospheric NO behaves, and could be used to increase the accuracy of future space weather and climate models. Thirteen years of NO flux data, observed at 100-250 km altitude by the SABER instrument onboard the TIMED satellite, is decomposed into five empirical orthogonal functions (EOFs) and their amplitudes to: 1) determine the strongest modes of variability in the data set, and 2) develop a compact model of NO flux. The first five EOFs account for 85% of the variability in the data, and their uncertainty is verified using cross-validation analysis. Although these linearly independent EOFs are not necessarily independent in a geophysical sense, the first three EOFs correlate strongly with different geophysical processes. The first EOF correlates strongly with Kp and F10.7, suggesting that geomagnetic storms and solar weather account for a large portion of NO flux variability. EOF 2 shows annual variations, and EOF 3 correlates with solar wind parameters. Using these relations, an empirical model of the EOF amplitudes can be derived, which could be used as a predictive tool for future NO emissions. We illustrate the NO model, highlight some of the hemispheric asymmetries, and discuss the geophysical associations of the EOFs.

Sparse Bayesian Inference and the Temperature Structure of the Solar Corona

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

Warren, Harry P.; Byers, Jeff M.; Crump, Nicholas A.

Measuring the temperature structure of the solar atmosphere is critical to understanding how it is heated to high temperatures. Unfortunately, the temperature of the upper atmosphere cannot be observed directly, but must be inferred from spectrally resolved observations of individual emission lines that span a wide range of temperatures. Such observations are “inverted” to determine the distribution of plasma temperatures along the line of sight. This inversion is ill posed and, in the absence of regularization, tends to produce wildly oscillatory solutions. We introduce the application of sparse Bayesian inference to the problem of inferring the temperature structure of themore » solar corona. Within a Bayesian framework a preference for solutions that utilize a minimum number of basis functions can be encoded into the prior and many ad hoc assumptions can be avoided. We demonstrate the efficacy of the Bayesian approach by considering a test library of 40 assumed temperature distributions.« less

KSC-2013-2828

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2825

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2831

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2885

NASA Image and Video Library

2013-06-24

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, mission managers participate in a pre-launch dress rehearsal in the Launch Vehicle Data Center for NASA’s Interface Region Imaging Spectrograph, or IRIS, solar observatory. Scheduled for launch from Vandenberg on June 26 aboard an Orbital Sciences Pegasus XL rocket, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region in to the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun’s visible surface and upper atmosphere, is where most of the sun’s ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth’s climate. For more information, visit http://www.nasa.gov/iris. Photo credit: NASA/Daniel Casper

KSC-2013-2830

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2832

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2912

NASA Image and Video Library

2013-06-25

VANDENBERG AIR FORCE BASE, Calif. – Final checkouts are being completed at Vandenberg Air Force Base in California as preparations continue for the launch from the L-1011 carrier aircraft of the Orbital Sciences Corp. Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/ Daniel Casper

KSC-2013-2833

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2824

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2888

NASA Image and Video Library

2013-06-24

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, mission managers participate in a pre-launch dress rehearsal in the Launch Vehicle Data Center for NASA’s Interface Region Imaging Spectrograph, or IRIS, solar observatory. Scheduled for launch from Vandenberg on June 26 aboard an Orbital Sciences Pegasus XL rocket, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region in to the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun’s visible surface and upper atmosphere, is where most of the sun’s ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth’s climate. For more information, visit http://www.nasa.gov/iris. Photo credit: NASA/Daniel Casper

KSC-2013-2827

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2826

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2887

NASA Image and Video Library

2013-06-24

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, mission managers participate in a pre-launch dress rehearsal in the Launch Vehicle Data Center for NASA’s Interface Region Imaging Spectrograph, or IRIS, solar observatory. Scheduled for launch from Vandenberg on June 26 aboard an Orbital Sciences Pegasus XL rocket, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region in to the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun’s visible surface and upper atmosphere, is where most of the sun’s ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth’s climate. For more information, visit http://www.nasa.gov/iris. Photo credit: NASA/Daniel Casper

KSC-2013-2911

NASA Image and Video Library

2013-06-25

VANDENBERG AIR FORCE BASE, Calif. – Final checkouts are being completed at Vandenberg Air Force Base in California as preparations continue for the launch from the L-1011 carrier aircraft of the Orbital Sciences Corp. Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/ Daniel Casper

KSC-2013-2829

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2886

NASA Image and Video Library

2013-06-24

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, mission managers participate in a pre-launch dress rehearsal in the Launch Vehicle Data Center for NASA’s Interface Region Imaging Spectrograph, or IRIS, solar observatory. Scheduled for launch from Vandenberg on June 26 aboard an Orbital Sciences Pegasus XL rocket, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region in to the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun’s visible surface and upper atmosphere, is where most of the sun’s ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth’s climate. For more information, visit http://www.nasa.gov/iris. Photo credit: NASA/Daniel Casper

KSC-2013-2834

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – Technicians and engineers at Vandenberg Air Force Base in California mate the Pegasus XL rocket with the Interface Region Imaging Spectrograph, or IRIS, solar observatory to the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

Measurements of the Magnetic Field of the Upper Chromosphere with Polarimetry

NASA Technical Reports Server (NTRS)

Rachmeler, Laurel; Mckenzie, David; Winebarger, Amy; Kobayashi, Ken; Ishikawa, Ryohko; Kubo, Masahito; Narukage, Noriyuki; Bueno, Trujillo, Javier; Auchere, Frederic

2017-01-01

A major remaining challenge for heliophysics is to decipher the magnetic structure of the chromosphere. The chromosphere is the critical interface between the Sun's photosphere and corona: it contains more mass than the entire interplanetary heliosphere, requires a heating rate that is larger than that of the corona, and mediates all the energy driving the solar wind, solar atmospheric heating and solar eruptions. While measurements of the magnetic field in the photosphere are routine, the chromosphere poses several extra challenges. The magnetically sensitive lines formed in the upper chromosphere are in the ultraviolet, so space-based observations are required. The lines are often formed over a range of heights, sampling different plasma which complicates the inversion process. These lines are sensitive to the magnetic field via polarized light that is created or modified through the Hanle and Zeeman effects. There are a few observations of these lines, and a significant challenge remains in extracting the magnetic field from the polarization measurements, as detailed model atmospheres with advanced radiative transfer physics are needed. Real progress is obtained by a simultaneous improvement in both the observational side and the modeling side. We present information on the CLASP (Chromospheric LAyer Spectro-Polarimeter) sounding rocket program, and future prospects for these types of measurements.

Increase in the Stratospheric NO2 Content Derived from Results of Ground-Based Observations after the October 2003 Solar Proton Event

NASA Astrophysics Data System (ADS)

Ageyeva, V. Yu.; Gruzdev, A. N.; Elokhov, A. S.

2018-04-01

This paper reports on the first experimental evidence of the impact of a solar proton event on the stratospheric NO2 content derived from ground-based spectrometric measurements at middle and high latitudes of the Northern Hemisphere. In October 2003, a solar proton event caused an increase in the NO2 content in the upper stratosphere by 0.6 × 1015 cm-2, which accounted for about one-third of the increase in the column NO2 content. Solar proton events may be an essential factor for variability of the column NO2 content in the atmosphere of the high and middle latitudes.

SPICAM: studying the global structure and composition of the Martian atmosphere

NASA Astrophysics Data System (ADS)

Bertaux, J.-L.; Fonteyn, D.; Korablev, O.; Chassefre, E.; Dimarellis, E.; Dubois, J. P.; Hauchecorne, A.; Lefèvre, F.; Cabane, M.; Rannou, P.; Levasseur-Regourd, A. C.; Cernogora, G.; Quemerais, E.; Hermans, C.; Kockarts, G.; Lippens, C.; de Maziere, M.; Moreau, D.; Muller, C.; Neefs, E.; Simon, P. C.; Forget, F.; Hourdin, F.; Talagrand, O.; Moroz, V. I.; Rodin, A.; Sandel, B.; Stern, A.

2004-08-01

The SPICAM (SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument consists of two spectrometers. The UV spectrometer addresses key issues about ozone and its H2O coupling, aerosols, the atmospheric vertical temperature structure and the ionosphere. The IR spectrometer is aimed primarily at H2O and abundances and vertical profiling of H2O and aerosols. SPICAM's density/temperature profiles will aid the development of meteorological and dynamical atmospheric models from the surface up to 160 km altitude. UV observations of the upper atmosphere will study the ionosphere and its direct interaction with the solar wind. They will also allow a better understanding of escape mechanisms, crucial for insight into the long-term evolution of the atmosphere.

Physics of the Space Environment

NASA Astrophysics Data System (ADS)

Vasyliünas, Vytenis M.

This book, one in the Cambridge Atmospheric and Space Science Series, joins a growing list of advanced-level textbooks in a field of study and research known under a variety of names: space plasma physics, solar-terrestrial or solar-planetary relations, space weather, or (the official name of the relevant AGU section) space physics and aeronomy. On the basis of graduate courses taught by the author in various departments at the University of Michigan, complete with problems and with appendices of physical constants and mathematical identities, this is indeed a textbook, systematic and severe in its approach. The book is divided into three parts, in length ratios of roughly 6:4:5. Part I, “Theoretical Description of Gases and Plasmas,” starts by writing down Maxwell's equations and the Lorentz transformation (no nonsense about any introductory material of a descriptive or historical nature) and proceeds through particle orbit theory, kinetics, and plasma physics with fluid and MHD approximations to waves, shocks, and energetic particle transport. Part II, “The Upper Atmosphere,” features chapters on the terrestrial upper atmosphere, airglow and aurora, and the ionosphere. Part III, “Sun-Earth Connection,” deals with the Sun, the solar wind, cosmic rays, and the terrestrial magnetosphere. The book thus covers, with two exceptions, just about all the topics of interest to Space Physics and Aeronomy scientists, and then some (the chapter on the Sun, for instance, briefly discusses also topics of the solar interior: thermonuclear energy generation, equilibrium structure, energy transfer, with a page or two on each). One exception reflects a strong geocentric bias: there is not one word in the main text on magnetospheres and ionospheres of other planets and their interaction with the solar wind (they are mentioned in a few problems). The other exception: the chapter on the terrestrial magnetosphere lacks a systematic exposition of the theory of magnetosphereionosphere coupling.

Laboratory for Extraterrestrial Physics

NASA Technical Reports Server (NTRS)

Vondrak, Richard R. (Technical Monitor)

2001-01-01

The NASA Goddard Space Flight Center (GSFC) Laboratory for Extraterrestrial Physics (LEP) performs experimental and theoretical research on the heliosphere, the interstellar medium, and the magnetospheres and upper atmospheres of the planets, including Earth. LEP space scientists investigate the structure and dynamics of the magnetospheres of the planets including Earth. Their research programs encompass the magnetic fields intrinsic to many planetary bodies as well as their charged-particle environments and plasma-wave emissions. The LEP also conducts research into the nature of planetary ionospheres and their coupling to both the upper atmospheres and their magnetospheres. Finally, the LEP carries out a broad-based research program in heliospheric physics covering the origins of the solar wind, its propagation outward through the solar system all the way to its termination where it encounters the local interstellar medium. Special emphasis is placed on the study of solar coronal mass ejections (CME's), shock waves, and the structure and properties of the fast and slow solar wind. LEP planetary scientists study the chemistry and physics of planetary stratospheres and tropospheres and of solar system bodies including meteorites, asteroids, comets, and planets. The LEP conducts a focused program in astronomy, particularly in the infrared and in short as well as very long radio wavelengths. We also perform an extensive program of laboratory research, including spectroscopy and physical chemistry related to astronomical objects. The Laboratory proposes, develops, fabricates, and integrates experiments on Earth-orbiting, planetary, and heliospheric spacecraft to measure the characteristics of planetary atmospheres and magnetic fields, and electromagnetic fields and plasmas in space. We design and develop spectrometric instrumentation for continuum and spectral line observations in the x-ray, gamma-ray, infrared, and radio regimes; these are flown on spacecraft to study the interplanetary medium, asteroids, comets, and planets. Suborbital sounding rockets and groundbased observing platforms form an integral part of these research activities. This report covers the period from approximately October 1999 through September 2000.

Sun and Sky Radiance Measurements and Data Analysis Protocols. Chapter 5

NASA Technical Reports Server (NTRS)

Frouin, Robert; Holben, Brent; Miller, Mark; Pietras, Christophe; Porter, John; Voss, Ken

2001-01-01

This chapter is concerned with two types of radiometric measurements essential to verify atmospheric correction algorithms and to calibrate vicariously satellite ocean color sensors. The first type is a photometric measurement of the direct solar beam to determine the optical thickness of the atmosphere. The intensity of the solar beam can be measured directly, or obtained indirectly from measurements of diffuse global upper hemispheric irradiance. The second type is a measurement of the solar aureole and sky radiance distribution using a CCD camera, or a scanning radiometer viewing in and perpendicular to the solar principal plane. From the two types of measurements, the optical properties of aerosols, highly variable in space and time, can be derived. Because of the high variability, the aerosol properties should be known at the time of satellite overpass. Atmospheric optics measurements, however, are not easy to perform at sea, from a ship or any platform. This complicates the measurement protocols and data analysis. Some instrumentation cannot be deployed at sea, and is limited to island and coastal sites. In the following, measurement protocols are described for radiometers commonly used to measure direct atmospheric transmittance and sky radiance, namely standard sun photometers, fast-rotating shadow-band radiometers, automated sky scanning systems, and CCD cameras. Methods and procedures to analyze and quality control the data are discussed, as well as proper measurement strategies for evaluation of atmospheric correction algorithms and satellite-derived ocean color.

Solar atmospheric dynamics. II - Nonlinear models of the photospheric and chromospheric oscillations

NASA Technical Reports Server (NTRS)

Leibacher, J.; Gouttebroze, P.; Stein, R. F.

1982-01-01

The one-dimensional, nonlinear dynamics of the solar atmosphere is investigated, and models of the observed photospheric (300 s) and chromospheric (200 s) oscillations are described. These are resonances of acoustic wave cavities formed by the variation of the temperature and ionization between the subphotospheric, hydrogen convection zone and the chromosphere-corona transition region. The dependence of the oscillations upon the excitation and boundary conditions leads to the conclusion that for the observed amplitudes, the modes are independently excited and, as trapped modes, transport little if any mechanical flux. In the upper photosphere and lower chromosphere, where the two modes have comparable energy density, interference between them leads to apparent vertical phase delays which might be interpreted as evidence of an energy flux.

The polar thermosphere of Venus

NASA Astrophysics Data System (ADS)

Mueller-Wodarg, Ingo; Rosenblatt, Pascal; Bruinsma, Sean; Yelle, Roger; Svedhem, Håkan; Forbes, Jeffrey M.; Withers, Paul; Keating Sci. Gerald, Sr.; Lopez-Valverde, Miguel Angel

The thermosphere of Venus has been extensively observed in-situ primarily by the Pioneer Venus Orbiter, but those measurements concentrated on the low latitude regions. Until recently, no in-situ observations were made of the polar thermosphere of Venus, and reference atmospheres such as the VTS3 and VIRA models relied on solar zenith angle trends inferred at low latitudes in order to extrapolate to polar latitudes. The Venus Express Atmospheric Drag Experiment (VExADE) carries out accurate orbital tracking in order to infer for the first time ever the densities in Venus' polar thermosphere near 180 km altitude at solar minimum. During 3 recent tracking campaigns we obtained density measurements that allow us to compare actual densities in those regions with those predicted by the reference atmosphere models. We constructed a hydrostatic diffusive equilibrium at-mosphere model that interpolates between the Venus Express remote sensing measurements in the upper mesosphere and lower thermosphere region and the in-situ drag measurements by VExADE. This paper will present and discuss our latest findings.

The SUVIT Instrument on the Solar-C Mission

NASA Astrophysics Data System (ADS)

Tarbell, Theodore D.; Ichimoto, Kiyoshi

2014-06-01

Solar-C is a new space mission being proposed to JAXA, with significant contributions anticipated from NASA, ESA, and EU countries. The main scientific objectives are to: reveal the mechanisms for heating and dynamics of the chromosphere and corona and acceleration of the solar wind; determine the physical origin of the large-scale explosions and eruptions that drive short-term solar, heliospheric, and geospace variability; use the solar atmosphere as a laboratory for understanding fundamental physical processes; make unprecedented observations of the polar magnetic fields. The unique approaches of Solar-C to achieve these goals are to: determine the properties and evolution of the 3-dimensional magnetic field, especially on small spatial scales, and for the first time observed in the crucial low beta plasma region; observe all the temperature regimes of the atmosphere seamlessly at the highest spatial resolution ever achieved; observe at high cadence the prevailing dynamics in all regions of the atmosphere; determine physical properties from high resolution spectroscopic measurements throughout the atmosphere and into the solar wind. The powerful suite of instruments onboard Solar-C will be sensitive to temperatures from the photosphere 5500 K) to solar flares 20 MK) with no temperature gap, with spatial resolution at all temperatures of 0.3″ or less (0.1″ in the lower atmosphere) and at high cadence. The purpose of the Solar UV-Visible-IR Telescope (SUVIT) is to obtain chromospheric velocity, temperature, density and magnetic field diagnostics over as wide arange of heights as possible, through high cadence spectral line profiles and vector spectro-polarimetry. SUVIT is a meter-class telescope currently under study at 1.4m in order to obtain sufficientresolution and S/N. SUVIT has two complementary focal plane packages, the Filtergraph that makes high cadence imaging observations with the highest spatial resolution and the Spectro-polarimeter that makes precise spectro-polarimetric observations. With their powerful sets of spectral lines, FG and SP collect physical measurements from the lower photosphere to upper chromosphere with much better spatial and temporal resolution than Hinode SOT.

Apparatus and method for the horizontal, crucible-free growth of silicon sheet crystals

DOEpatents

Ciszek, T.F.

1984-09-12

Apparatus is provided for continuously forming a silicon crystal sheet from a silicon rod in a non-crucible environment. The rod is rotated and fed toward an RF coil in an inert atmosphere so that the upper end of the rod becomes molten and the silicon sheet crystal is pulled therefrom substantially horizontally in a continuous strip. A shorting ring may be provided around the rod to limit the heating to the upper end only. Argon gas can be used to create the inert atmosphere within a suitable closed chamber. By use of this apparatus and method, a substantially defect-free silicon crystal sheet is formed which can be used for micro-circuitry chips or solar cells.

Why CO2 cools the middle atmosphere - a consolidating model perspective

NASA Astrophysics Data System (ADS)

Goessling, Helge F.; Bathiany, Sebastian

2016-08-01

Complex models of the atmosphere show that increased carbon dioxide (CO2) concentrations, while warming the surface and troposphere, lead to lower temperatures in the stratosphere and mesosphere. This cooling, which is often referred to as "stratospheric cooling", is evident also in observations and considered to be one of the fingerprints of anthropogenic global warming. Although the responsible mechanisms have been identified, they have mostly been discussed heuristically, incompletely, or in combination with other effects such as ozone depletion, leaving the subject prone to misconceptions. Here we use a one-dimensional window-grey radiation model of the atmosphere to illustrate the physical essence of the mechanisms by which CO2 cools the stratosphere and mesosphere: (i) the blocking effect, associated with a cooling due to the fact that CO2 absorbs radiation at wavelengths where the atmosphere is already relatively opaque, and (ii) the indirect solar effect, associated with a cooling in places where an additional (solar) heating term is present (which on Earth is particularly the case in the upper parts of the ozone layer). By contrast, in the grey model without solar heating within the atmosphere, the cooling aloft is only a transient blocking phenomenon that is completely compensated as the surface attains its warmer equilibrium. Moreover, we quantify the relative contribution of these effects by simulating the response to an abrupt increase in CO2 (and chlorofluorocarbon) concentrations with an atmospheric general circulation model. We find that the two permanent effects contribute roughly equally to the CO2-induced cooling, with the indirect solar effect dominating around the stratopause and the blocking effect dominating otherwise.

Active Upper-atmosphere Chemistry and Dynamics from Polar Circulation Reversal on Titan

NASA Technical Reports Server (NTRS)

Teanby, Nicholas A.; Irwin, Patrick Gerard Joseph; Nixon, Conor A.; DeKok, Remco; Vinatier, Sandrine; Coustenis, Athena; Sefton-Nash, Elliot; Calcutt, Simon B.; Flasar, Michael F.

2012-01-01

Saturn's moon Titan has a nitrogen atmosphere comparable to Earth's, with a surface pressure of 1.4 bar. Numerical models reproduce the tropospheric conditions very well but have trouble explaining the observed middle-atmosphere temperatures, composition and winds. The top of the middle-atmosphere circulation has been thought to lie at an altitude of 450 to 500 kilometres, where there is a layer of haze that appears to be separated from the main haze deck. This 'detached' haze was previously explained as being due to the colocation of peak haze production and the limit of dynamical transport by the circulation's upper branch. Herewe report a build-up of trace gases over the south pole approximately two years after observing the 2009 post-equinox circulation reversal, from which we conclude that middle-atmosphere circulation must extend to an altitude of at least 600 kilometres. The primary drivers of this circulation are summer-hemisphere heating of haze by absorption of solar radiation and winter-hemisphere cooling due to infrared emission by haze and trace gases; our results therefore imply that these effects are important well into the thermosphere (altitudes higher than 500 kilometres). This requires both active upper-atmosphere chemistry, consistent with the detection of high-complexity molecules and ions at altitudes greater than 950 kilometres, and an alternative explanation for the detached haze, such as a transition in haze particle growth from monomers to fractal structures.

History of Chandra X-Ray Observatory

NASA Image and Video Library

2001-07-04

Giving scientists their first look, Chandra observed x-rays produced by fluorescent radiation from oxygen atoms of the Sun in the sparse upper atmosphere of Mars, about 120 kilometers (75 miles) above its surface. The x-ray power detected from the Martian atmosphere is very small, amounting to only 4 megawatts, comparable to the x-ray power of about ten thousand medical x-ray machines. At the time of the Chandra observation, a huge dust storm developed on Mars that covered about one hemisphere, later to cover the entire planet. This hemisphere rotated out of view over the 9-hour observation, but no change was observed in the x-ray intensity indicating that the dust storm did not affect the upper atmosphere. Scientists also observed a halo of x-rays extending out to 7,000 kilometers above the surface of Mars believed to be produced by collisions of ions racing away from the Sun (the solar wind).

KSC-2013-3366

NASA Image and Video Library

2013-08-21

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician inspects a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Jim Grossmann MAVEN is being prepared inside the facility for its scheduled November launch aboard a United Launch Alliance Atlas V rocket to Mars. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. Photo credit: NASA/Jim Grossmann

KSC-2013-3367

NASA Image and Video Library

2013-08-21

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician repairs a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Jim Grossmann MAVEN is being prepared inside the facility for its scheduled November launch aboard a United Launch Alliance Atlas V rocket to Mars. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. Photo credit: NASA/Jim Grossmann

KSC-2013-3372

NASA Image and Video Library

2013-08-21

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician cleans a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Jim Grossmann MAVEN is being prepared inside the facility for its scheduled November launch aboard a United Launch Alliance Atlas V rocket to Mars. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. Photo credit: NASA/Jim Grossmann

Chandra Image Gives First Look at Mars Emitted X-Rays

NASA Technical Reports Server (NTRS)

2001-01-01

Giving scientists their first look, Chandra observed x-rays produced by fluorescent radiation from oxygen atoms of the Sun in the sparse upper atmosphere of Mars, about 120 kilometers (75 miles) above its surface. The x-ray power detected from the Martian atmosphere is very small, amounting to only 4 megawatts, comparable to the x-ray power of about ten thousand medical x-ray machines. At the time of the Chandra observation, a huge dust storm developed on Mars that covered about one hemisphere, later to cover the entire planet. This hemisphere rotated out of view over the 9-hour observation, but no change was observed in the x-ray intensity indicating that the dust storm did not affect the upper atmosphere. Scientists also observed a halo of x-rays extending out to 7,000 kilometers above the surface of Mars believed to be produced by collisions of ions racing away from the Sun (the solar wind).

KSC-2013-3365

NASA Image and Video Library

2013-08-21

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician inspects a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/Jim Grossmann MAVEN is being prepared inside the facility for its scheduled November launch aboard a United Launch Alliance Atlas V rocket to Mars. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. Photo credit: NASA/Jim Grossmann

A solar radiation model for use in climate studies

NASA Technical Reports Server (NTRS)

Chou, Ming-Dah

1992-01-01

A solar radiation routine is developed for use in climate studies that includes absorption and scattering due to ozone, water vapor, oxygen, carbon dioxide, clouds, and aerosols. Rayleigh scattering is also included. Broadband parameterization is used to compute the absorption by water vapor in a clear atmosphere, and the k-distribution method is applied to compute fluxes in a scattering atmosphere. The reflectivity and transmissivity of a scattering layer are computed analytically using the delta-four-stream discrete-ordinate approximation. The two-stream adding method is then applied to compute fluxes for a composite of clear and scattering layers. Compared to the results of high spectral resolution and detailed multiple-scattering calculations, fluxes and heating rate are accurately computed to within a few percent. The high accuracy of the flux and heating-rate calculations is achieved with a reasonable amount of computing time. With the UV and visible region grouped into four bands, this solar radiation routine is useful not only for climate studies but also for studies on photolysis in the upper atmosphere and photosynthesis in the biosphere.

Analysis of data from spacecraft (stratospheric warmings)

NASA Technical Reports Server (NTRS)

1974-01-01

The details of the stratospheric warming processes as to time, area, and intensity were established, and the warmings with other terrestrial and solar phenomena occurring at satellite platform altitudes, or observable from satellite platforms, were correlated. Links were sought between the perturbed upper atmosphere (mesosphere and thermosphere) and the stratosphere that might explain stratospheric warmings.

Non-LTE models of Titan's upper atmosphere

NASA Technical Reports Server (NTRS)

Yelle, Roger V.

1991-01-01

Models for the thermal structure of Titan's upper atmosphere, between 0.1 mbar and 0.01 nbar are presented. The calculations include non-LTE heating/cooling in the rotation-vibration bands of CH4, C2H2, and C2H6, absorption of solar IR radiation in the near-IR bands of CH4 and subsequent cascading to the nu-4 band of CH4, absorption of solar EUV and UV radiation, thermal conduction and cooling by HCN rotational lines. Unlike earlier models, the calculated exospheric temperature agrees well with observations, because of the importance of HCN cooling. The calculations predict a well-developed mesopause with a temperature of 135-140 K at an altitude of approximately 600 km and pressure of about 0.1 microbar. The mesopause is at a higher pressure than predicted by earlier calculations because non-LTE radiative transfer in the rotation-vibration bands of CH4, C2H2, and C2H6 is treated in an accurate manner. The accuracy of the LTE approximation for source functions and heating rates is discussed.

A Magnetic Reconnection Event in the Solar Atmosphere Driven by Relaxation of a Twisted Arch Filament System

NASA Astrophysics Data System (ADS)

Huang, Zhenghua; Mou, Chaozhou; Fu, Hui; Deng, Linhua; Li, Bo; Xia, Lidong

2018-02-01

We present high-resolution observations of a magnetic reconnection event in the solar atmosphere taken with the New Vacuum Solar Telescope, Atmospheric Imaging Assembly (AIA), and Helioseismic and Magnetic Imager (HMI). The reconnection event occurred between the threads of a twisted arch filament system (AFS) and coronal loops. Our observations reveal that the relaxation of the twisted AFS drives some of its threads to encounter the coronal loops, providing inflows of the reconnection. The reconnection is evidenced by flared X-shape features in the AIA images, a current-sheet-like feature apparently connecting post-reconnection loops in the Hα + 1 Å images, small-scale magnetic cancelation in the HMI magnetograms and flows with speeds of 40–80 km s‑1 along the coronal loops. The post-reconnection coronal loops seen in the AIA 94 Å passband appear to remain bright for a relatively long time, suggesting that they have been heated and/or filled up by dense plasmas previously stored in the AFS threads. Our observations suggest that the twisted magnetic system could release its free magnetic energy into the upper solar atmosphere through reconnection processes. While the plasma pressure in the reconnecting flux tubes are significantly different, the reconfiguration of field lines could result in transferring of mass among them and induce heating therein.

On the Observed Changes in Upper Stratospheric and Mesospheric Temperatures from UARS HALOE

NASA Technical Reports Server (NTRS)

Remsberg, Ellis E.

2006-01-01

Temperature versus pressure or T(p) time series from the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) have been extended and re-analyzed for the period of 1991-2005 and for the upper stratosphere and mesosphere in 10-degree wide latitude zones from 60S to 60N. Even though sampling from a solar occultation experiment is somewhat limited, it is shown to be quite adequate for developing both the seasonal and longer-term variations in T(p). Multiple linear regression (MLR) techniques were used in the re-analyses for the seasonal and the significant interannual, solar cycle (SC-like or decadal-scale), and linear trend terms. A simple SC-like term of 11-yr period was fitted to the time series residuals after accounting for the seasonal and interannual terms. Highly significant SC-like responses were found for both the upper mesosphere and the upper stratosphere. The phases of these SC-like terms were checked for their continuity with latitude and pressure-altitude, and in almost all cases they are directly in-phase with that of standard proxies for the solar flux variations. The analyzed, max minus min, responses at low latitudes are of order 1 K, while at middle latitudes they are as large as 3 K in the upper mesosphere. Highly significant, linear cooling trends were found at middle latitudes of the middle to upper mesosphere (about -2 K/decade), at tropical latitudes of the middle mesosphere (about -1 K/decade), and at 2 hPa (or order -1 K/decade).

THE FORMATION OF IRIS DIAGNOSTICS. II. THE FORMATION OF THE Mg II h and k LINES IN THE SOLAR ATMOSPHERE

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

Leenaarts, J.; Pereira, T. M. D.; Carlsson, M.

NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission will study how the solar atmosphere is energized. IRIS contains an imaging spectrograph that covers the Mg II h and k lines as well as a slit-jaw imager centered at Mg II k. Understanding the observations requires forward modeling of Mg II h and k line formation from three-dimensional (3D) radiation-magnetohydrodynamic (RMHD) models. This paper is the second in a series where we undertake this modeling. We compute the vertically emergent h and k intensity from a snapshot of a dynamic 3D RMHD model of the solar atmosphere, and investigate whichmore » diagnostic information about the atmosphere is contained in the synthetic line profiles. We find that the Doppler shift of the central line depression correlates strongly with the vertical velocity at optical depth unity, which is typically located less than 200 km below the transition region (TR). By combining the Doppler shifts of the h and k lines we can retrieve the sign of the velocity gradient just below the TR. The intensity in the central line depression is anti-correlated with the formation height, especially in subfields of a few square Mm. This intensity could thus be used to measure the spatial variation of the height of the TR. The intensity in the line-core emission peaks correlates with the temperature at its formation height, especially for strong emission peaks. The peaks can thus be exploited as a temperature diagnostic. The wavelength difference between the blue and red peaks provides a diagnostic of the velocity gradients in the upper chromosphere. The intensity ratio of the blue and red peaks correlates strongly with the average velocity in the upper chromosphere. We conclude that the Mg II h and k lines are excellent probes of the very upper chromosphere just below the TR, a height regime that is impossible to probe with other spectral lines. They also provide decent temperature and velocity diagnostics of the middle chromosphere.« less

Solar Coronal Jets: Observations, Theory, and Modeling

NASA Technical Reports Server (NTRS)

Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.; Sterling, A. C.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.; DeVore, C. R.; Archontis, V.;

Solar Coronal Jets: Observations, Theory, and Modeling

NASA Technical Reports Server (NTRS)

Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.; Sterling, A.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.; Devore, C. R.; Archontis, V.;

NOy production, ozone loss and changes in net radiative heating due to energetic particle precipitation in 2002-2010

NASA Astrophysics Data System (ADS)

Sinnhuber, Miriam; Berger, Uwe; Funke, Bernd; Nieder, Holger; Reddmann, Thomas; Stiller, Gabriele; Versick, Stefan; von Clarmann, Thomas; Maik Wissing, Jan

2018-01-01

We analyze the impact of energetic particle precipitation on the stratospheric nitrogen budget, ozone abundances and net radiative heating using results from three global chemistry-climate models considering solar protons and geomagnetic forcing due to auroral or radiation belt electrons. Two of the models cover the atmosphere up to the lower thermosphere, the source region of auroral NO production. Geomagnetic forcing in these models is included by prescribed ionization rates. One model reaches up to about 80 km, and geomagnetic forcing is included by applying an upper boundary condition of auroral NO mixing ratios parameterized as a function of geomagnetic activity. Despite the differences in the implementation of the particle effect, the resulting modeled NOy in the upper mesosphere agrees well between all three models, demonstrating that geomagnetic forcing is represented in a consistent way either by prescribing ionization rates or by prescribing NOy at the model top.Compared with observations of stratospheric and mesospheric NOy from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument for the years 2002-2010, the model simulations reproduce the spatial pattern and temporal evolution well. However, after strong sudden stratospheric warmings, particle-induced NOy is underestimated by both high-top models, and after the solar proton event in October 2003, NOy is overestimated by all three models. Model results indicate that the large solar proton event in October 2003 contributed about 1-2 Gmol (109 mol) NOy per hemisphere to the stratospheric NOy budget, while downwelling of auroral NOx from the upper mesosphere and lower thermosphere contributes up to 4 Gmol NOy. Accumulation over time leads to a constant particle-induced background of about 0.5-1 Gmol per hemisphere during solar minimum, and up to 2 Gmol per hemisphere during solar maximum. Related negative anomalies of ozone are predicted by the models in nearly every polar winter, ranging from 10-50 % during solar maximum to 2-10 % during solar minimum. Ozone loss continues throughout polar summer after strong solar proton events in the Southern Hemisphere and after large sudden stratospheric warmings in the Northern Hemisphere. During mid-winter, the ozone loss causes a reduction of the infrared radiative cooling, i.e., a positive change of the net radiative heating (effective warming), in agreement with analyses of geomagnetic forcing in stratospheric temperatures which show a warming in the late winter upper stratosphere. In late winter and spring, the sign of the net radiative heating change turns to negative (effective cooling). This spring-time cooling lasts well into summer and continues until the following autumn after large solar proton events in the Southern Hemisphere, and after sudden stratospheric warmings in the Northern Hemisphere.

NASA’s MAVEN Mission Observes Ups and Downs of Water Escape from Mars

NASA Image and Video Library

2017-12-08

After investigating the upper atmosphere of the Red Planet for a full Martian year, NASA’s MAVEN mission has determined that the escaping water does not always go gently into space. Sophisticated measurements made by a suite of instruments on the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft revealed the ups and downs of hydrogen escape – and therefore water loss. The escape rate peaked when Mars was at its closest point to the sun and dropped off when the planet was farthest from the sun. The rate of loss varied dramatically overall, with 10 times more hydrogen escaping at the maximum. “MAVEN is giving us unprecedented detail about hydrogen escape from the upper atmosphere of Mars, and this is crucial for helping us figure out the total amount of water lost over billions of years,” said Ali Rahmati, a MAVEN team member at the University of California at Berkeley who analyzed data from two of the spacecraft’s instruments. Hydrogen in Mars’ upper atmosphere comes from water vapor in the lower atmosphere. An atmospheric water molecule can be broken apart by sunlight, releasing the two hydrogen atoms from the oxygen atom that they had been bound to. Several processes at work in Mars’ upper atmosphere may then act on the hydrogen, leading to its escape. Read more: go.nasa.gov/2dAgAV4 NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Living with a Star: New Opportunities in Sun-Climate Research

NASA Technical Reports Server (NTRS)

2003-01-01

Living With a Star is a NASA initiative employing the combination of dedicated spacecraft with targeted research and modeling efforts to improve what we know of solar effects of all kinds on the Earth and its surrounding space environment, with particular emphasis on those that have significant practical impacts on life and society. The highest priority among these concerns is the subject of this report: the potential effects of solar variability on regional and global climate, including the extent to which solar variability has contributed to the well-documented warming of the Earth in the last 100 years. Understanding how the climate system reacts to external forcing from the Sun will also greatly improve our knowledge of how climate will respond to other climate drivers, including those of anthropogenic origin. A parallel element of the LWS program addresses solar effects on space weather : the impulsive emissions of charged particles, short-wave electromagnetic radiation and magnetic disturbances in the upper atmosphere and near-Earth environment that also affect life and society. These include a wide variety of solar impacts on aeronautics, astronautics, electric power transmission, and national defense. Specific examples are (1) the impacts of potentially- damaging high energy radiation and atomic particles of solar origin on satellites and satellite operations, spacecraft electronics systems and components, electronic communications, electric power distribution grids, navigational and GPS systems, and high altitude aircraft; and (2) the threat of sporadic, high-energy solar radiation to astronauts and high altitude aircraft passengers and crews. Elements of the LWS program include an array of dedicated spacecraft in near- Earth and near-Sun orbits that will closely study and observe both the Sun itself and the impacts of its variations on the Earth's radiation belts and magnetosphere, the upper atmosphere, and ionosphere. These spacecraft, positioned to study and monitor changing conditions in the Sun-Earth neighborhood, will also serve as sentinels of solar storms and impulsive events.

Where does the Thermospheric Ionospheric GEospheric Research (TIGER) Program go?

NASA Astrophysics Data System (ADS)

Schmidtke, G.; Avakyan, S. V.; Berdermann, J.; Bothmer, V.; Cessateur, G.; Ciraolo, L.; Didkovsky, L.; Dudok de Wit, T.; Eparvier, F. G.; Gottwald, A.; Haberreiter, M.; Hammer, R.; Jacobi, Ch.; Jakowski, N.; Kretzschmar, M.; Lilensten, J.; Pfeifer, M.; Radicella, S. M.; Schäfer, R.; Schmidt, W.; Solomon, S. C.; Thuillier, G.; Tobiska, W. K.; Wieman, S.; Woods, T. N.

2015-10-01

At the 10th Thermospheric Ionospheric GEospheric Research (TIGER/COSPAR) symposium held in Moscow in 2014 the achievements from the start of TIGER in 1998 were summarized. During that period, great progress was made in measuring, understanding, and modeling the highly variable UV-Soft X-ray (XUV) solar spectral irradiance (SSI), and its effects on the upper atmosphere. However, after more than 50 years of work the radiometric accuracy of SSI observation is still an issue and requires further improvement. Based on the extreme ultraviolet (EUV) data from the SOLAR/SolACES, and SDO/EVE instruments, we present a combined data set for the spectral range from 16.5 to 105.5 nm covering a period of 3.5 years from 2011 through mid of 2014. This data set is used in ionospheric modeling of the global Total Electron Content (TEC), and in validating EUV SSI modeling. For further investigations the period of 3.5 years is being extended to about 12 years by including data from SOHO/SEM and TIMED/SEE instruments. Similarly, UV data are used in modeling activities. After summarizing the results, concepts are proposed for future real-time SSI measurements with in-flight calibration as experienced with the ISS SOLAR payload, for the development of a space weather camera for observing and investigating space weather phenomena in real-time, and for providing data sets for SSI and climate modeling. Other planned topics are the investigation of the relationship between solar EUV/UV and visible/near-infrared emissions, the impact of X-rays on the upper atmosphere, the development of solar EUV/UV indices for different applications, and establishing a shared TIGER data system for EUV/UV SSI data distribution and real-time streaming, also taking into account the achievements of the FP7 SOLID (First European SOLar Irradiance Data Exploitation) project. For further progress it is imperative that coordinating activities in this special field of solar-terrestrial relations and solar physics is emphasized.

STS-48 official crew insignia

NASA Image and Video Library

1999-08-27

STS048-S-001 (July 1991) --- Designed by the astronaut crew members, the patch represents the space shuttle orbiter Discovery in orbit about Earth after deploying the Upper Atmospheric Research Satellite (UARS) depicted in block letter style. The stars are those in the northern hemisphere as seen in the fall and winter when UARS will begin its study of Earth's atmosphere. The color bands on Earth's horizon, extending up to the UARS spacecraft, depict the study of Earth's atmosphere. The triangular shape represents the relationship among the three atmospheric processes that determine upper atmospheric structure and behavior: chemistry, dynamics and energy. In the words of the crew members, "This continuous process brings life to our planet and makes our planet unique in the solar system." The NASA insignia design for space shuttle flights is reserved for use by the astronauts and for other official use as the NASA Administrator may authorize. Public availability has been approved only in the form of illustrations by the various news media. When and if there is any change in this policy, which is not anticipated, it will be publicly announced. Photo credit: NASA

Preliminary Results on Mars and the Siding Spring Meteor Shower from MAVEN’s Imaging UV Spectrograph

NASA Astrophysics Data System (ADS)

Deighan, Justin; Schneider, Nicholas

2015-04-01

The MAVEN mission to Mars is designed to study the upper atmosphere and its response to external drivers, searching for clues to the cause of long-term atmospheric loss. MAVEN carries the Imaging UV Spectrograph (IUVS) for remote sensing studies of the atmosphere through vertical scans from the limb through the corona, UV imaging of the planet and stellar occultations. Each observational mode has successfully observed the spectral features and spatial distributions as intended, confirming and expanding our understanding of the Mars upper atmosphere as observed by the Mariner spacecraft and Mars Express. Furthermore, IUVS witnessed the aftermath of an intense meteor shower on Mars caused by Comet Siding Spring. For a period of many hours, the planet’s UV spectrum was dominated by emission from ionized magnesium deposited by meteor ablation in the upper atmosphere. Initial results from the originally-planned Mars observations include:• Significant persistent structures in the thermospheric day glow emissions, dependent primarily on solar zenith angle, along with significant variability on daily timescales• Nitric oxide nightglow and low-level auroral emissions of substantially greater nightside extent than previously seen• The first vertical profiles of the D/H ratio in the atmosphere and their evolution with Mars season• The most complete maps and vertical profiles of H, C and O in the Mars corona• The first global snapshot of the middle atmosphere obtained by a day-long stellar occultation campaignOther results from the missions’s preliminary phases will be included.

Energy transfer in O collisions with He isotopes and helium escape from Mars

NASA Astrophysics Data System (ADS)

Bovino, S.; Zhang, P.; Kharchenko, V.; Dalgarno, A.

2010-12-01

Helium is one of the dominant constituents in the upper atmosphere of Mars [1]. Thermal (Jeans’) escape of He is negligible on Mars [2] and major mechanism of escape is related to the collisional ejection of He atoms by energetic oxygen. Collisional ejection dominates over ion-related mechanisms [3] and evaluation of the escape flux of neutral He becomes an important issue. The dissociative recombination of O2+ is considered to be the major source of energetic oxygen atoms [4]. We report accurate data on energy-transfer collisions between hot oxygen atoms and the atmospheric helium gas. Angular dependent scattering cross sections for elastic collisions of O(3P) and O(1D) atoms with helium gas have been calculated quantum mechanically and found to be surprisingly similar. Cross sections, computed for collisions with both helium isotopes, 3He and 4He, have been used to construct the kernel of the Boltzmann equation, describing the energy relaxation of hot oxygen atoms. Computed rates of energy transfer in O + He collisions have been used to evaluate the flux of He atoms escaping from the Mars atmosphere at different solar conditions. We have identified atmospheric layers mostly responsible for production of the He escape flux. Our results are consistent with recent data from Monte Carlo simulations of the escape of O atoms: strong angular anisotropy of atomic cross sections leads to an increased transparency of the upper atmosphere for escaping O flux [5] and stimulate the collisional ejection of He atoms. References [1] Krasnopolsky, V. A., and G. R. Gladstone (2005), Helium on Mars and Venus: EUVE observations and modeling, Icarus, 176, 395. [2] Chassefiere E. and F. Leblanc (2004), Mars atmospheric escape and evolution; interaction with the solar wind, Planetary and Space Science, 52, 1039 [3] Krasnopolsky, V. (2010), Solar activity variations of thermospheric temperatures on Mars and a problem of CO in the lower atmoshpere, Icarus, 207, 638. [4] Fox, J. L. (1995), On the escape of oxygen and hydrogen from Mars, Geophy. Rev. Lett., 20, 1847. [5] Krestyanikova, M. A. and V. I. Shematovich (2006), Stochastic models of hot planetary and satellite coronas: a hot oxygen corona of Mars, Solar System Research, 40, 384.

A Reanalysis for the Seasonal and Longer-Period Cycles and the Trends in Middle Atmosphere Temperature from the HALOE

NASA Technical Reports Server (NTRS)

Remsberg, Ellis E.

2007-01-01

Previously published analyses for the seasonal and longer-period cycles in middle atmosphere temperature versus pressure (or T(p)) from the Halogen Occultation Experiment (HALOE) are extended to just over 14 years and updated to properly account for the effects of autocorrelation in its time series of zonally-averaged data. The updated seasonal terms and annual averages are provided, and they can be used to generate temperature distributions that are representative of the period 1991-2005. QBO-like terms have also been resolved and are provided, and they exhibit good consistency across the range of latitudes and pressure-altitudes. Further, exploratory analyses of the residuals from each of the 221 time series have yielded significant 11-yr solar cycle (or SC-like) and linear trend terms at a number of latitudes and levels. The amplitudes of the SC-like terms for the upper mesosphere agree reasonably with calculations of the direct solar radiative effects for T(p). Those SC amplitudes increase by about a factor of 2 from the lower to the upper mesosphere and are also larger at the middle than at the low latitudes. The diagnosed cooling trends for the subtropical latitudes are in the range, -0.5 to -1.0 K/decade, which is in good agreement with the findings from models of the radiative effects on pressure surfaces due to known increases in atmospheric CO2. The diagnosed trends are somewhat larger than predicted with models for the upper mesosphere of the northern hemisphere middle latitudes.

NASA's Earth Observing System (EOS): Observing the Atmosphere, Land, Oceans, and Ice from Space

NASA Technical Reports Server (NTRS)

King, Michael D.

2004-01-01

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During this year, the last of the first series of EOS missions, Aura, was launched. Aura is designed exclusively to conduct research on the composition, chemistry, and dynamics of the Earth's upper and lower atmosphere, employing multiple instruments on a single spacecraft. Aura is the third in a series of major Earth observing satellites to study the environment and climate change and is part of NASA's Earth Science Enterprise. The first and second missions, Terra and Aqua, are designed to study the land, oceans, atmospheric constituents (aerosols, clouds, temperature, and water vapor), and the Earth's radiation budget. The other seven EOS spacecraft include satellites to study (i) land cover & land use change, (ii) solar irradiance and solar spectral variation, (iii) ice volume, (iv) ocean processes (vector wind and sea surface topography), and (v) vertical variations of clouds, water vapor, and aerosols up to and including the stratosphere. Aura's chemistry measurements will also follow up on measurements that began with NASA's Upper Atmosphere Research Satellite and continue the record of satellite ozone data collected from the TOMS missions. In this presentation I will describe how scientists are using EOS data to examine the health of the earth's atmosphere, including atmospheric chemistry, aerosol properties, and cloud properties, with a special but not exclusive look at the latest earth observing mission, Aura.

NASA's Earth Observing System (EOS): Observing the Atmosphere, Land, Oceans, and Ice from Space

NASA Technical Reports Server (NTRS)

King, Michael D.

2005-01-01

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by whch scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During this year, the last of the first series of EOS missions, Aura, was launched. Aura is designed exclusively to conduct research on the composition, chemistry, and dynamics of the Earth's upper and lower atmosphere, employing multiple instruments on a single spacecraft. Aura is the third in a series of major Earth observing satellites to study the environment and climate change and is part of NASA's Earth Science Enterprise. The first and second missions, Terra and Aqua, are designed to study the land, oceans, atmospheric constituents (aerosols, clouds, temperature, and water vapor), and the Earth's radiation budget. The other seven EOS spacecraft include satellites to study (i) land cover & land use change, (ii) solar irradiance and solar spectral variation, (iii) ice volume, (iv) ocean processes (vector wind and sea surface topography), and (v) vertical variations of clouds, water vapor, and aerosols up to and including the stratosphere. Aura's chemistry measurements will also follow up on measurements that began with NASA's Upper Atmosphere Research Satellite and continue the record of satellite ozone data collected from the TOMS missions. In this presentation I will describe how scientists are using EOS data to examine the health of the earth's atmosphere, including atmospheric chemistry, aerosol properties, and cloud properties, with a special look at the latest earth observing mission, Aura.

Contributions of Lower Atmospheric Drivers to the Semiannual Oscillation in Thermospheric Global Mass Density

NASA Astrophysics Data System (ADS)

Jones, M., Jr.; Emmert, J. T.; Drob, D. P.; Siskind, D. E.

2016-12-01

The thermosphere exhibits intra-annual variations (IAV) in globally averaged mass density that noticeably impact the drag environment of satellites in low Earth orbit. Particularly, the annual and semiannual oscillations (AO and SAO) are collectively the second largest component, after solar variability, of thermospheric global mass density variations. Several mechanisms have been proposed to explain the oscillations, but they have yet to be reproduced by first-principles modeling simulations. Recent studies have focused on estimating the SAO in eddy diffusion required to explain the thermospheric SAO in mass density. Less attention has been paid to the effect of lower and middle atmospheric drivers on the lower boundary of the thermosphere. In this study, we utilize the National Center for Atmospheric Research Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM), to elucidate how the different lower atmospheric drivers influence IAV, and in particular the SAO of globally-averaged thermospheric mass density. We performed numerical simulations of a continuous calendar year assuming constant solar forcing, manipulating the lower atmospheric tidal forcing and gravity wave parameterization in order to quantify the SAO in thermospheric mass density attributable to different lower atmospheric drivers. The prominent initial results are as follows: (1) The "standard" TIME-GCM is capable of simulating the SAO in globally-averaged mass density at 400 km from first-principles, and its amplitude and phase compare well with empirical models; (2) The simulations suggest that seasonally varying Kzz driven by breaking GWs is not the primary driver of the SAO in upper thermospheric globally averaged mass density; (3) Preliminary analysis suggests that the SAO in the upper thermospheric mass density could be a by-product of dynamical wave transport in the mesopause region.

Ionospheric Irregularities at Mars Probed by MARSIS Topside Sounding

NASA Astrophysics Data System (ADS)

Harada, Y.; Gurnett, D. A.; Kopf, A. J.; Halekas, J. S.; Ruhunusiri, S.

2018-01-01

The upper ionosphere of Mars contains a variety of perturbations driven by solar wind forcing from above and upward propagating atmospheric waves from below. Here we explore the global distribution and variability of ionospheric irregularities around the exobase at Mars by analyzing topside sounding data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express. As irregular structure gives rise to off-vertical echoes with excess propagation time, the diffuseness of ionospheric echo traces can be used as a diagnostic tool for perturbed reflection surfaces. The observed properties of diffuse echoes above unmagnetized regions suggest that ionospheric irregularities with horizontal wavelengths of tens to hundreds of kilometers are particularly enhanced in the winter hemisphere and at high solar zenith angles. Given the known inverse dependence of neutral gravity wave amplitudes on the background atmospheric temperature, the ionospheric irregularities probed by MARSIS are most likely associated with plasma perturbations driven by atmospheric gravity waves. Though extreme events with unusually diffuse echoes are more frequently observed for high solar wind dynamic pressures during some time intervals, the vast majority of the diffuse echo events are unaffected by varying solar wind conditions, implying limited influence of solar wind forcing on the generation of ionospheric irregularities. Combination of remote and in situ measurements of ionospheric irregularities would offer the opportunity for a better understanding of the ionospheric dynamics at Mars.

The response of middle atmospheric ozone to solar UV irradiance variations with a period of 27 days

NASA Technical Reports Server (NTRS)

Chen, LI; Brasseur, Guy; London, Julius

1994-01-01

A one-dimensional photochemical-dynamical-radiative time-dependent model was used to study the response of middle atmospheric temperature and ozone to solar UV irradiance variations with the period of 27 days. The model solar UV O(x), HO(x), NO(x), and CIO(x)families and modeled solar UV variations. The amplitude of the primary temperature response to the solar UV variation is plus 0.4 K at 85-90 km with a phase lag of about 6 days. A secondary maximum response of plus 0.3 K at 45-50 km appears with a phase lag of 1 day. There is a maximum positive ozone response to the 27-day solar UV oscillation of 2.5 percent at 80-90 km with a phase lag of about 10 days after the solar irradiance maximum. At 70 km the ozone response is about 1.2 percent and is out of phase with the solar variation. In the upper stratosphere (40-50 km) the relative ozone variation is small, about 0.2 percent to 0.3 percent, and there is a negative phase of about 4 days between the ozone and solar oscillations. These oscillations are in phase in the middle stratosphere (35-40 km) where there is again a maximum relative response of about 0.6 percent. The reasons for these ozone amplitude and phase variations are discussed.

Solar Irradiance Variability and Its Impacts on the Earth Climate System

NASA Astrophysics Data System (ADS)

Harder, J. W.; Woods, T. N.

The Sun plays a vital role in the evolution of the climates of terrestrial planets. Observations of the solar spectrum are now routinely made that span the wavelength range from the X-ray portion of the spectrum (5 nm) into the infrared to about 2400 nm. Over this very broad wavelength range, accounting for about 97% of the total solar irradiance, the intensity varies by more than 6 orders of magnitude, requiring a suite of very different and innovative instruments to determine both the spectral irradiance and its variability. The origins of solar variability are strongly linked to surface magnetic field changes, and analysis of solar images and magnetograms show that the intensity of emitted radiation from solar surface features in active regions has a very strong wavelength and magnetic field strength dependence. These magnetic fields produce observable solar surface features such as sunspots, faculae, and network structures that contribute in different ways to the radiated output. Semi-empirical models of solar spectral irradiance are able to capture much of the Sun's output, but this topic remains an active area of research. Studies of solar structures in both high spectral and spatial resolution are refining this understanding. Advances in Earth observation systems and high-quality three-dimensional chemical climate models provide a sound methodology to study the mechanisms of the interaction between Earth's atmosphere and the incoming solar radiation. Energetic photons have a profound effect on the chemistry and dynamics of the thermosphere and ionosphere, and these processes are now well represented in upper atmospheric models. In the middle and lower atmosphere the effects of solar variability enter the climate system through two nonexclusive pathways referred to as the top-down and bottom-up mechanisms. The top-down mechanism proceeds through the alteration of the photochemical rates that establish the middle atmospheric temperature structure and circulation patterns. In the bottom-up mechanism, the increased solar cycle forcing at Earth's surface increases the latent heat flux and evaporation processes, thereby altering the tropical wind patterns.

Effects of Meteorological Variability on the Thermosphere-Ionosphere System during the Moderate Geomagnetic Disturbed January 2013 Period As Simulated By Time-GCM

NASA Astrophysics Data System (ADS)

Maute, A. I.; Hagan, M. E.; Richmond, A. D.; Liu, H.; Yudin, V. A.

2014-12-01

The ionosphere-thermosphere system is affected by solar and magnetospheric processes and by meteorological variability. Ionospheric observations of total electron content during the current solar cycle have shown that variability associated with meteorological forcing is important during solar minimum, and can have significant ionospheric effects during solar medium to maximum conditions. Numerical models can be used to study the comparative importance of geomagnetic and meterological forcing.This study focuses on the January 2013 Stratospheric Sudden Warming (SSW) period, which is associated with a very disturbed middle atmosphere as well as with moderately disturbed solar geomagntic conditions. We employ the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) with a nudging scheme using Whole-Atmosphere-Community-Climate-Model-Extended (WACCM-X)/Goddard Earth Observing System Model, Version 5 (GEOS5) results to simulate the effects of the meteorological and solar wind forcing on the upper atmosphere. The model results are evaluated by comparing with observations e.g., TEC, NmF2, ion drifts. We study the effect of the SSW on the wave spectrum, and the associated changes in the low latitude vertical drifts. These changes are compared to the impact of the moderate geomagnetic forcing on the TI-system during the January 2013 time period by conducting numerical experiments. We will present select highlights from our study and elude to the comparative importance of the forcing from above and below as simulated by the TIME-GCM.

Sun, Earth and man: The need to know. The quest for knowledge of Sun-Earth relations

NASA Technical Reports Server (NTRS)

Stafford, E. P.

1982-01-01

Solar physics and the effects of emanations from the Sun on communications and Earth's weather and climate are discussed. Scientific interest in the solar system from the old Stone Age to the present is reviewed with particular emphasis on the objectives sought and information obtained by Explorer satellites, Pioneer satellites, Skylab, Helios, ISEE, the solar maximum mission, and the Dynamics Explorer. The goals of missions planned for the 1980's are discussed including those using space shuttle, Spacelab, the Solar Mesosphere Explorer, the solar optical telescope, the upper atmosphere research satellite, and the solar probe. The objectives of the international solar polar mission and of the Origin of Plasma in Earth's Neighborhood mission are also delineated. Other missions being considered are reviewed and the prospect of taming the fusion process to provide clean, harmless electrical energy like that obtained from the Sun is entertained.

SUMER: Solar Ultraviolet Measurements of Emitted Radiation

NASA Technical Reports Server (NTRS)

Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuehne, M.; Lemaire, P.; Marsch, E.

1992-01-01

The experiment Solar Ultraviolet Measurements of Emitted Radiation (SUMER) is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. Specifically, SUMER will measure profiles and intensities of Extreme Ultraviolet (EUV) lines emitted in the solar atmosphere ranging from the upper chromosphere to the lower corona; determine line broadenings, spectral positions and Doppler shifts with high accuracy, provide stigmatic images of selected areas of the Sun in the EUV with high spatial, temporal and spectral resolution and obtain full images of the Sun and the inner corona in selectable EUV lines, corresponding to a temperature from 10,000 to more than 1,800,000 K.

Naval Research Laboratory 1986 Review

DTIC Science & Technology

1986-01-01

Behavior and Properties of Materials 84 Constrained- Layer Damping of Structure-Borne Sound 85 Computer-Controlled Emissivity Measurement System 87...Epitaxial Layers 128 Phase-Controlltd Gyrotron Oscillators 130 -SiC Transistor Development 133 Kinetic Inductance Microstrip Lines 136 Energetic...experiments in --- the areas of upper atmospheric, solar , and astro- ., ._ .nomical research aboard NASA, DoD, and foreign space projects. Division

Greenhouse Effect Detection Experiment (GEDEX). Selected data sets

NASA Technical Reports Server (NTRS)

Olsen, Lola M.; Warnock, Archibald, III

1992-01-01

This CD-ROM contains selected data sets compiled by the participants of the Greenhouse Effect Detection Experiment (GEDEX) workshop on atmospheric temperature. The data sets include surface, upper air, and/or satellite-derived measurements of temperature, solar irradiance, clouds, greenhouse gases, fluxes, albedo, aerosols, ozone, and water vapor, along with Southern Oscillation Indices and Quasi-Biennial Oscillation statistics.

Physics of the infrared spectrum

NASA Technical Reports Server (NTRS)

Deming, Drake; Jennings, Donald E.; Jefferies, John; Lindsey, Charles

1991-01-01

The IR bandpass is attractive for solar magnetic field studies in virtue of the proportionality to wavelength of the ratio of Zeeman splitting to line width. The large Zeeman splitting and optical thinness of the 12-micron observations render them especially useful for vector magnetic field derivations. The IR continuum, and many IR spectral lines, are formed in LTE and are useful in studies of the temperature structure of the solar atmosphere from the deepest observable photospheric layers to chromospheric altitudes. The far-IR continuum is an excellent thermometer for the upper photosphere and chromosphere.

Characterizing the UV environment of GJ1214b

NASA Astrophysics Data System (ADS)

Desert, Jean-Michel

2010-09-01

The recent detection of a super-Earth transiting a nearby low-mass star GJ1214 {Charbonneau et al., 2009} has opened the door to testing the predictions of low mass planet atmosphere theories. Theoretical models predict that low mass planets are likely to exist with atmospheres that can vary widely in their composition and structure. Some super-Earths may be able to retain massive hydrogen-rich atmospheres. Others might never accumulate hydrogen or experience significant escape of lightweight elements, resulting in atmospheres more like those of the terrestrial planets in our Solar System. Planets which orbit close to their parent stars, such as close-in hot-Jupiters and super-Earths, are exposed to strong XEUV flux that influence their atmospheres and may trigger atmospheric escape processes. This phenomenon, which shapes planetary atmospheres, determines the evolution of the planet. This can also dramatically enhance the detectability of a heavily irradiated hydrogen atmosphere when the planet transits in front of its parent star. We propose to use HST/STIS/G140M to determine the intensity and variability of the Lyman-alpha chromospheric emission line and provide observational constraints to super-Earth atmospheric models. We propose to coordinate this measurement with a planetary transit in order to detect large upper atmospheric signatures if present. This short measurement also enables us to determine whether a larger program dedicated to upper atmospheric study is feasible for a following cycle.

Understanding of Jupiter's Atmosphere after the Galileo Probe Entry

NASA Technical Reports Server (NTRS)

Fonda, Mark (Technical Monitor); Young, Richard E.

2003-01-01

Instruments on the Galileo probe measured composition, cloud properties, thermal structure, winds, radiative energy balance, and electrical properties of the Jovian atmosphere. As expected the probe results confirm some expectations about Jupiter's atmosphere, refute others, and raise new questions which still remain unanswered. This talk will concentrate on those aspects of the probe observations which either raised new questions or remain unresolved. The Galileo probe observations of composition and clouds provided some of the biggest surprises of the mission. Helium abundance measured by the probe differed significantly from the remote sensing derivations from Voyager. Discrepancy between the Voyager helium abundance determinations for Jupiter and the Galileo probe value have now led to a considerably increased helium determination for Saturn. Global abundance of N in the form of ammonia was observed to be super-solar by approximately the same factor as carbon, in contrast to expectations that C/N would be significantly larger than solar. This has implications for the formation and evolution of Jupiter. The cloud structure was not what was generally anticipated, even though most previous remote sensing results below the uppermost cloud referred to 5 micron hot spots, local regions with reduced cloud opacity. The Galileo probe descended in one of these hot spots. Only a tenuous, presumed ammomium hydrosulfide, cloud was detected, and no significant water cloud or super-solar water abundance was measured. The mixing ratios as a function of depth for the condensibles ammonia, hydrogen sulfide, and water, exhibited no apparent correlation with either condensation levels or with each other, an observation that is still a puzzle, although there are now dynamical models of hot spots which show promise in being able to explain such behavior. Probe tracked zonal winds show that wind magnitude increases with depth to pressures of about 4 bars, with the winds extending to at least as deep as the probe made measurements, 22 bars. Models of hot spot dynamics raise the possibility that the variation with depth of the probe measured zonal winds between 0.4 and 4 bars reflect the dynamics of the hot spot rather than the global wind pattern. Galileo upper atmosphere measurements established that there is a sharp temperature rise with altitude between about 350 and 800 km above the 1 bar pressure level, with the upper atmosphere reaching temperatures near 900 K. The energy sources for this upper atmosphere heating are not clearly established, but various mechanisms have been proposed. These and other aspects of the Galileo probe data will be discussed.

Comparative ionospheres: Terrestrial and giant planets

NASA Astrophysics Data System (ADS)

Mendillo, Michael; Trovato, Jeffrey; Moore, Luke; Müller-Wodarg, Ingo

2018-03-01

The study of planetary ionospheres within our solar system offers a variety of settings to probe mechanisms of photo-ionization, chemical loss, and plasma transport. Ionospheres are a minor component of upper atmospheres, and thus their mix of ions observed depends on the neutral gas composition of their parent atmospheres. The same solar irradiance (x-rays and extreme-ultra-violet vs. wavelength) impinges upon each of these atmospheres, with solar flux magnitudes changed only by the inverse square of distance from the Sun. If all planets had the same neutral atmosphere-with ionospheres governed by photochemical equilibrium (production = loss)-their peak electron densities would decrease as the inverse of distance from the Sun, and any changes in solar output would exhibit coherent effects throughout the solar system. Here we examine the outer planet with the most observations of its ionosphere (Saturn) and compare its patterns of electron density with those at Earth under the same-day solar conditions. We show that, while the average magnitudes of the major layers of molecular ions at Earth and Saturn are approximately in accord with distance effects, only minor correlations exist between solar effects and day-to-day electron densities. This is in marked contrast to the strong correlations found between the ionospheres of Earth and Mars. Moreover, the variability observed for Saturn's ionosphere (maximum electron density and total electron content) is much larger than found at Earth and Mars. With solar irradiance changes far too small to cause such effects, we use model results to explore the roles of other agents. We find that water sources from Enceladus at low latitudes, and 'ring rain' at middle latitudes, contribute substantially to variability via water ion chemistry. Thermospheric winds and electrodynamics generated at auroral latitudes are suggested causes of high latitude ionospheric variability, but remain inconclusive due to the lack of relevant observations.

Effect of the Solar UV/EUV Heating on the Intensity and Spatial Distribution of Jupiter's Synchrotron Radiation

NASA Astrophysics Data System (ADS)

Kita, Hajime; Misawa, H.; Tsuchiya, F.; Tao, C.; Morioka, A.

2012-10-01

Jupiter's synchrotron radiation (JSR) is the emission from relativistic electrons, and it is the most effective probe for remote sensing of Jupiter's radiation belt from the Earth. Recent observations reveal short term variations of JSR with the time scale of days to weeks. Brice and McDonough (1973) proposed that the solar UV/EUV heating for Jupiter's upper atmosphere causes enhancement of total flux density. If such a process occurs at Jupiter, it is also expected that diurnal wind system produces dawn-dusk asymmetry of the JSR brightness distribution. Preceding studies confirmed that the short term variations in total flux density correspond to the solar UV/EUV. However, the effect of solar UV/EUV heating on the brightness distribution has not been confirmed. Hence, the purpose of this study is to confirm the solar UV/EUV heating effect on total flux density and brightness distribution. We made radio imaging analysis using the National Radio Astronomy Observatory (NRAO) archived data of the Very Large Array (VLA) obtained in 2000, and following results were shown. 1, Total flux density varied corresponding to the solar UV/EUV. 2, Dawn side emission was brighter than dusk side emission almost every day. 3, Variations of the dawn-dusk asymmetry did not correspond to the solar UV/EUV. In order to explain the second result, we estimate the diurnal wind velocity from the observed dawn-dusk ratio by using the model brightness distribution of JSR. Estimated neutral wind velocity is 46+/-11 m/s, which reasonably corresponds to the numerical simulation of Jupiter's upper atmosphere. In order to explain the third result, we examined the effect of the global convection electric field driven by tailward outflow of plasma in Jupiter's magnetosphere. As the result, it is suggested that typical fluctuation of the convection electric field strength was enough to cause the observed variations of the dawn-dusk asymmetry.

Technical Note: A Time-Dependent I(sub 0) Correction for Solar Occultation Instruments

NASA Technical Reports Server (NTRS)

Burton, Sharon P.; Thomason, Larry W.; Zawodny, Joseph M.

2009-01-01

Solar occultation has proven to be a reliable technique for the measurement of atmospheric constituents in the stratosphere. NASA's Stratospheric Aerosol and Gas Experiments (SAGE, SAGE II, and SAGE III) together have provided over 25 years of quality solar occultation data, a data record which has been an important resource for the scientific exploration of atmospheric composition and climate change. Herein, we describe an improvement to the processing of SAGE data that corrects for a previously uncorrected short-term timedependence in the calibration function. The variability relates to the apparent rotation of the scanning track with respect to the face of the sun due to the motion of the satellite. Correcting for this effect results in a decrease in the measurement noise in the Level 1 line-of-sight optical depth measurements of approximately 40% in the middle and upper stratospheric SAGE II and III where it has been applied. The technique is potentially useful for any scanning solar occultation instrument, and suggests further improvement for future occultation measurements if a full disk imaging system can be included.

Molecular Oxygen in the Thermosphere: Issues and Measurement Strategies

NASA Astrophysics Data System (ADS)

Picone, J. M.; Hedin, A. E.; Drob, D. P.; Meier, R. R.; Bishop, J.; Budzien, S. A.

2002-05-01

We review the state of empirical knowledge regarding the distribution of molecular oxygen in the lower thermosphere (100-200 km), as embodied by the new NRLMSISE-00 empirical atmospheric model, its predecessors, and the underlying databases. For altitudes above 120 km, the two major classes of data (mass spectrometer and solar ultraviolet [UV] absorption) disagree significantly regarding the magnitude of the O2 density and the dependence on solar activity. As a result, the addition of the Solar Maximum Mission (SMM) data set (based on solar UV absorption) to the NRLMSIS database has directly impacted the new model, increasing the complexity of the model's formulation and generally reducing the thermospheric O2 density relative to MSISE-90. Beyond interest in the thermosphere itself, this issue materially affects detailed models of ionospheric chemistry and dynamics as well as modeling of the upper atmospheric airglow. Because these are key elements of both experimental and operational systems which measure and forecast the near-Earth space environment, we present strategies for augmenting the database through analysis of existing data and through future measurements in order to resolve this issue.

CLASP2: The Chromospheric LAyer Spectro-Polarimeter

NASA Technical Reports Server (NTRS)

Mckenzie, D. E.; Ishikawa, R.; Bueno, J. Trujillo; Auchere, F.; Rachmeler, L.; Kubo, M.; Kobayashi, K.; Winebarger, A.; Bethge, C.; Narukage, N.;

CLASP2: The Chromospheric LAyer Spectro-Polarimeter

NASA Technical Reports Server (NTRS)

McKenzie, D. E.; Ishikawa, R.; Bueno, J. Trujillo; Auchere, F.; Rachmeler, L; Kudo, M.; Kobayashi, K.; Winebarger, A.; Bethge, C.; Narukage, N.;

Pioneer Venus 1978

NASA Technical Reports Server (NTRS)

1976-01-01

An orbiter and a multiprobe spacecraft will be sent to Venus in 1978 to conduct a detailed examination of the planet's atmosphere and weather. The spin-stabilized multiprobe spacecraft consists of a bus, a large probe and three identical small probes, each carrying a complement of scientific instruments. The large probe will conduct a detailed sounding of the lower atmosphere, obtaining measurements of the clouds, atmospheric structure, wind speed, and atmospheric composition. Primary emphasis will be placed on the planet's energy balance and clouds. The three small probes will provide information on the circulation pattern of the lower atmosphere. The probe bus will provide data on the upper atmosphere and ionosphere down to an altitude of about 120 km. The orbiter is designed to globally map the atmosphere, ionosphere, and the solar wind/ionosphere interaction. In addition, it will utilize radar mapping techniques to study the surface.

Detection of acetylene in the Saturnian atmosphere, using the IUE satellite

NASA Technical Reports Server (NTRS)

Moos, H. W.; Clarke, J. T.

1979-01-01

Direct evidence for the presence of acetylene in the upper part of the Saturnian atmosphere is reported. This evidence consists of two spectra of Saturn obtained by using the low-dispersion mode of the short-wavelength spectrograph on the IUE satellite. A series of distinct absorption bands in the reflected solar radiation at 1750 A is attributed to acetylene. The reciprocal of the acetylene cross section at 1750 A is shown to imply 7 x 10 to the 17th molecules/sq cm in the reflecting layer. It is concluded that the radiation at 1750 A originates from less than 2.3 km-amagat within the atmosphere.

Solar cycle modulation of Southern Annular Mode -Energy-momentum analysis-

NASA Astrophysics Data System (ADS)

Kuroda, Y.

2016-12-01

Climate is affected by various factors, including oceanic changes and volcanic eruptions. 11-year solar cycle change is one of such important factors. Observational analysis shows that the Southern Annular Mode (SAM) in late-winter/spring show structural modulation associated with 11-year solar cycle. In fact, SAM-related signal tends to extend from surface to upper stratosphere and persistent longer period in the High Solar (HS) years, whereas it is restricted in the troposphere and not persist in the Low Solar (LS) years. In the present study, we used 35-year record of ERA-Interim reanalysis data and performed wave-energy and momentum analysis on the solar-cycle modulation of the SAM to examine key factors to create such solar-SAM relationship. It is found that enhanced wave-mean flow interaction tends to take place in the middle stratosphere in association with enhanced energy input from diabatic heating on September only in HS years. The result suggests atmospheric and solar conditions on September are keys to create solar-SAM relationship.

Middle Atmospheric Changes Caused by the January and March 2012 Solar Proton Events

NASA Technical Reports Server (NTRS)

Jackman, C. H.; Randall, C. E.; Harvey, V. L.; Wang, S.; Fleming, E. L.; Lopez-Puertas, M.; Funke, B.; Bernath, P. F.

2014-01-01

The recent 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic solar protons produced considerable ionization of the neutral atmosphere as well as HOx (H, OH, HO2) and NOx (N, NO, NO2). We compute a NOx production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which places these SPE periods among the 12 largest in the past 50 years. Aura Microwave Limb Sounder (MLS) observations of the peroxy radical, HO2, show significant enhancements of 0.9 ppbv in the northern polar mesosphere as a result of these SPE periods. Both MLS measurements and Goddard Space Flight Center (GSFC) two-dimensional (2D) model predictions indicated middle mesospheric ozone decreases of 20 percent for several days in the northern polar region with maximum depletions 60 percent as a result of the HOx produced in both the January and March 2012 SPE periods. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE) and the Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instruments measured NO and NO2 (NOx), which indicated enhancements of over 20 ppbv in most of the northern polar mesosphere for several days as a result of these SPE periods. The GSFC 2D model was used to predict the medium-term (months) influence and found that the polar Southern Hemisphere middle atmosphere ozone was most affected by these solar events due to the increased downward motion in the fall and early winter. The downward transport moved the SPE-produced NOy to lower altitudes and led to predicted modest destruction of ozone (5-9 percent) in the upper stratosphere days to weeks after the March 2012 event. Total ozone reductions were predicted to be a maximum of 1 percent in 2012 due to these SPEs.

Recent progress in empirical modeling of ion composition in the topside ionosphere

NASA Astrophysics Data System (ADS)

Truhlik, Vladimir; Triskova, Ludmila; Bilitza, Dieter; Kotov, Dmytro; Bogomaz, Oleksandr; Domnin, Igor

2016-07-01

The last deep and prolonged solar minimum revealed shortcomings of existing empirical models, especially of parameter models that depend strongly on solar activity, such as the IRI (International Reference Ionosphere) ion composition model, and that are based on data sets from previous solar cycles. We have improved the TTS-03 ion composition model (Triskova et al., 2003) which is included in IRI since version 2007. The new model called AEIKion-13 employs an improved description of the dependence of ion composition on solar activity. We have also developed new global models of the upper transition height based on large data sets of vertical electron density profiles from ISIS, Alouette and COSMIC. The upper transition height is used as an anchor point for adjustment of the AEIKion-13 ion composition model. Additionally, we show also progress on improvements of the altitudinal dependence of the ion composition in the AEIKion-13 model. Results of the improved model are compared with data from other types of measurements including data from the Atmosphere Explorer C and E and C/NOFS satellites, and the Kharkiv and Arecibo incoherent scatter radars. Possible real time updating of the model by the upper transition height from the real time COSMIC vertical profiles is discussed. Triskova, L.,Truhlik,V., Smilauer, J.,2003. An empirical model of ion composition in the outer ionosphere. Adv. Space Res. 31(3), 653-663.

The 1991 research and technology report, Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Soffen, Gerald (Editor); Ottenstein, Howard (Editor); Montgomery, Harry (Editor); Truszkowski, Walter (Editor); Frost, Kenneth (Editor); Sullivan, Walter (Editor); Boyle, Charles (Editor)

1991-01-01

The 1991 Research and Technology Report for Goddard Space Flight Center is presented. Research covered areas such as (1) earth sciences including upper atmosphere, lower atmosphere, oceans, hydrology, and global studies; (2) space sciences including solar studies, planetary studies, Astro-1, gamma ray investigations, and astrophysics; (3) flight projects; (4) engineering including robotics, mechanical engineering, electronics, imaging and optics, thermal and cryogenic studies, and balloons; and (5) ground systems, networks, and communications including data and networks, TDRSS, mission planning and scheduling, and software development and test.

Flight performance of the Pioneer Venus Orbiter solar array

NASA Technical Reports Server (NTRS)

Goldhammer, L. J.; Powe, J. S.; Smith, Marcie

1987-01-01

The Pioneer Venus Orbiter (PVO) solar panel power output capability has degraded much more severely than has the power output capability of solar panels that have operated in earth-orbiting spacecraft for comparable periods of time. The incidence of solar proton events recorded by the spacecraft's scientific instruments accounts for this phenomenon only in part. It cannot explain two specific forms of anomalous behavior observed: 1) a variation of output per spin with roll angle, and 2) a gradual degradation of the maximum output. Analysis indicates that the most probable cause of the first anomaly is that the solar cells underneath the spacecraft's magnetometer boom have been damaged by a reverse biasing of the cells that occurs during pulsed shadowing of the cells by the boom as the spacecraft rotates. The second anomaly might be caused by the effects on the solar array of substances from the upper atmosphere of Venus.

CIV VUV FPI Interferometer for Transition Region Magnetography

NASA Technical Reports Server (NTRS)

Gary, G. A.

2005-01-01

Much in the same way photonics harnesses light for engineering and technology applications, solar physics harnesses light for the remote sensing of the sun. In photonics the vacuum ultraviolet region offers shorter wavelength and higher energies per photon, while in solar physics the VUV allows the remote sensing of the upper levels of the solar atmosphere where magnetic fields dominate the physics. Understanding solar magnetism is a major aim for astrophysics and for understanding solar-terrestrial interaction. The poster is on our instrument development program for a high-spectral-resolution, high-finesse, Vacuum Ultraviolet Fabry-Perot Interferometer (VUV FPI) for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CIV (155nm). The poster will cover how the V W interferometer will allow us to understand solar magnetism, what is special about the MSFC VUV FPI, and why the University of Toronto F2 eximer has been of particular value to this program.

Empirical model of atomic nitrogen in the upper thermosphere

NASA Technical Reports Server (NTRS)

Engebretson, M. J.; Mauersberger, K.; Kayser, D. C.; Potter, W. E.; Nier, A. O.

1977-01-01

Atomic nitrogen number densities in the upper thermosphere measured by the open source neutral mass spectrometer (OSS) on Atmosphere Explorer-C during 1974 and part of 1975 have been used to construct a global empirical model at an altitude of 375 km based on a spherical harmonic expansion. The most evident features of the model are large diurnal and seasonal variations of atomic nitrogen and only a moderate and latitude-dependent density increase during periods of geomagnetic activity. Maximum and minimum N number densities at 375 km for periods of low solar activity are 3.6 x 10 to the 6th/cu cm at 1500 LST (local solar time) and low latitude in the summer hemisphere and 1.5 x 10 to the 5th/cu cm at 0200 LST at mid-latitudes in the winter hemisphere.

Chemistry and evolution of Titan's atmosphere

NASA Technical Reports Server (NTRS)

Strobel, D. F.

1982-01-01

The chemistry and evolution of Titan's atmosphere are reviewed, in light of the scientific findings from the Voyager mission. It is argued that the present N2 atmosphere may be Titan's initial atmosphere, rather than one photochemically derived from an original NH3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH4 is irreversibly converted to less hydrogen-rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of about 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N2 into hot, escaping N atoms to remove about 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar EUV energy deposition in Titan's atmosphere by an order of magnitude, and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region.

KSC-2013-2835

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, the Pegasus XL rocket with the attached Interface Region Imaging Spectrograph IRIS solar observatory rolled out of the hangar on its transporter to the runway at Vandenberg. There, the rocket and spacecraft were mated with the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2839

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, the Pegasus XL rocket with the attached Interface Region Imaging Spectrograph IRIS solar observatory rolled out of the hangar on its transporter to the runway at Vandenberg. There, the rocket and spacecraft were mated with the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2837

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, the Pegasus XL rocket with the attached Interface Region Imaging Spectrograph IRIS solar observatory rolled out of the hangar on its transporter to the runway at Vandenberg. There, the rocket and spacecraft were mated with the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2840

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, the Pegasus XL rocket with the attached Interface Region Imaging Spectrograph IRIS solar observatory rolled out of the hangar on its transporter to the runway at Vandenberg. There, the rocket and spacecraft were mated with the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

KSC-2013-2843

NASA Image and Video Library

2013-06-19

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, the Pegasus XL rocket with the attached Interface Region Imaging Spectrograph IRIS solar observatory rolled out of the hangar on its transporter to the runway at Vandenberg. There, the rocket and spacecraft were mated with the Orbital Sciences L-1011 carrier aircraft. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/Randy Beaudoin

Thermal structure and heat balance of the outer planets

NASA Technical Reports Server (NTRS)

Conrath, B. J.; Hanel, R. A.; Samuelson, R. E.

1989-01-01

Current knowledge of the thermal structure and energy balance of the outer planets is summarized. The Voyager spacecraft experiments have provided extensive new information on the atmospheric temperatures and energetics of Jupiter, Saturn and Uranus. All three planets show remarkably small global-scale horizontal thermal contrast, indicating efficient redistribution of heat within the atmospheres or interiors. Horizontal temperature gradients on the scale of the zonal jets indicate that the winds decay with height in the upper troposphere. This suggests that the winds are driven at deeper levels and are subjected to frictional damping of unknown origin at higher levels. Both Jupiter and Saturn have internal power sources equal to about 70 percent of the absorbed solar power. This result is consistent with the view that significant helium differentiation has occurred on Saturn. Uranus has an internal power no greater than 13 percent of the absorbed solar power, while earth-based observations suggest Neptune has an internal power in excess of 100 percent of the absorbed solar power.

Solar Storm's Radiation at Martian Orbit and Surface

NASA Image and Video Library

2017-09-29

Energetic particles from a large solar storm in September 2017 were seen both in Mars orbit and on the surface of Mars by NASA missions to the Red Planet. The horizontal axis for both parts of this graphic is the time from Sept. 10 to Sept. 15, 2017. The upper portion of this graphic shows the increase in protons in two ranges of energy levels (15- to-100 million electron volts and 80-to-220 million electron volts), as recorded by the Solar Energetic Particle instrument on NASA's on NASA's Mars Atmosphere and Volatile Evolution orbiter, or MAVEN. The lower portion shows the radiation dose on the Martian surface, in micrograys per day, as measured by the Radiation Assessment Monitor instrument on NASA' Curiosity Mars rover. Micrograys are unit of measurement for absorbed radiation dose. Note that only protons in the higher bracket of energy levels penetrate the atmosphere enough to be detected on the surface. https://photojournal.jpl.nasa.gov/catalog/PIA21856

Chromospheric Heating Driven by Cancellations of Internetwork Magnetic Flux

NASA Astrophysics Data System (ADS)

Gosic, M.; de la Cruz Rodriguez, J.; De Pontieu, B.; Bellot Rubio, L.; Esteban Pozuelo, S.; Ortiz-Carbonell, A. N.

2017-12-01

The heating of the solar chromosphere remains to be one of the most important questions in solar physics. It is believed that this phenomenon may significantly be supported by small-scale internetwork (IN) magnetic fields. Indeed, cancellations of IN magnetic flux can generate transient brightenings in the chromosphere and transition region. These bright structures might be the signature of energy release and plasma heating, probably driven by magnetic reconnection of IN field lines. Using high resolution, multiwavelength, coordinated observations recorded with the Interface Region Imaging Spectrograph (IRIS) and the Swedish 1-m Solar Telescope (SST), we analyzed cancellations of IN flux and their impact on the energetics and dynamics of the quiet Sun atmosphere. From their temporal and spatial evolution, we determine that these events can heat locally the upper atmospheric layers. However, employing multi-line inversions of the Mg II h & k lines, we show that cancellations, although occurring ubiquitously over IN regions, are not capable of sustaining the total radiative losses of the quiet Sun chromosphere.

Peculiarities of Ionospheric Response to Solar Eruptive Events

NASA Astrophysics Data System (ADS)

Cadez, V. M.; Nina, A.

2013-05-01

Solar eruptive events such as flares and coronal mass ejections (CMEs) affect the terrestrial upper atmosphere, the magnetosphere and ionosphere in particular, through sudden impacts of additional X-ray radiation and by increased intensity of the solar wind. As a consequence, a variety perturbation features occur locally as well as globally in the plasma medium in space around the Earth. We study some of such transient phenomena taking place at low altitudes of the ionosphere (below 90 km) by monitoring and analyzing registered amplitude and phase time variations of VLF radio waves with given frequencies. The main object of this research is gaining an additional insight into the structure and physical properties of the lower ionosphere.

Atmospheric Laboratory for Applications and Science (ATLAS), mission 1: Introduction

NASA Technical Reports Server (NTRS)

1988-01-01

The first Atmospheric Laboratory for Applications and Science (ATLAS 1) is a NASA mission with an international payload, with the European Space Agency providing operational support for the European investigations. The ATLAS 1 represents the first of a series of shuttle-borne payloads which are intended to study the composition of the middle atmosphere and its possible variations due to solar changes over the course of an 11-year solar cycle. One of the ATLAS missions will coincide with NASA's Upper Atmospheric Research Satellite (UARS) mission and will provide crucial parameters not measured by the instrument complement on the satellite. A first in this evolutionary program, the ATLAS 1 will carry a payload of instruments originally flown on the Spacelab 1 and Spacelab 3 missions. The ATLAS mission therefore exploits the shuttle capability to return sophisticated instruments to the ground for refurbishment and updating, and the multi-mission reflight of the instruments at intervals required by the scientific goals. In addition to the investigations specific to the ATLAS objectives, the first mission payload includes others that are intended to study or use the near earth environment.

Multi-wavelength search for complex molecules in Titan's Atmosphere

NASA Astrophysics Data System (ADS)

Nixon, C. A.; Cordiner, M. A.; Greathouse, T. K.; Richter, M.; Kisiel, Z.; Irwin, P. G.; Teanby, N. A.; Kuan, Y. J.; Charnley, S. B.

2017-12-01

Titan's atmosphere is one of the most complex astrochemical environments known: the photochemistry of methane and nitrogen, induced by solar UV and Saturn magnetospheric electron impacts, creates a bonanza of organic molecules like no other place in the solar system. Cassini has unveiled the first glimpses of Titan's chemical wonderland, but many gaps remain. In particular, interpreting the mass spectra of Titan's upper atmosphere requires external knowledge, to disentangle the signature of molecules from their identical-mass brethren. Cassini infrared spectroscopy with CIRS has helped to some extent, but is also limited by low spectral resolution. Potentially to the rescue, comes high-resolution spectroscopy from the Earth at infrared and sub-millimeter wavelengths, where molecules exhibit vibrational and rotational transitions respectively. In this presentation, we describe the quest to make new, unique identifications of large molecules in Titan's atmosphere, focusing specifically on cyclic molecules including N-heterocycles. This molecular family is of high astrobiological significance, forming the basic ring structure for DNA nucleobases. We present the latest spectroscopic observations of Titan from ALMA and NASA's IRTF telescope, discussing present findings and directions for future work.

New measurements quantify atmospheric greenhouse effect

NASA Astrophysics Data System (ADS)

Bhattacharya, Atreyee

2012-10-01

In spite of a large body of existing measurements of incoming short-wave solar radiation and outgoing long-wave terrestrial radiation at the surface of the Earth and, more recently, in the upper atmosphere, there are few observations documenting how radiation profiles change through the atmosphere—information that is necessary to fully quantify the greenhouse effect of Earth's atmosphere. Through the use of existing technology but employing improvements in observational techniques it may now be possible not only to quantify but also to understand how different components of the atmosphere (e.g., concentration of gases, cloud cover, moisture, and aerosols) contribute to the greenhouse effect. Using weather balloons equipped with radiosondes, Philipona et al. continuously measured radiation fluxes from the surface of Earth up to altitudes of 35 kilometers in the upper stratosphere. Combining data from flights conducted during both day and night with continuous 24-hour measurements made at the surface of the Earth, the researchers created radiation profiles of all four components necessary to fully capture the radiation budget of Earth, namely, the upward and downward short-wave and long-wave radiation as a function of altitude.

Influence of Suprathermal Atoms on the Escape and Evolution of Mars' CO2 Atmosphere

NASA Astrophysics Data System (ADS)

Lichtenegger, H.; Amerstorfer, U. V.; Gröller, H.; Tian, F.; Lammer, H.; Noack, L.; Johnstone, C.; Tu, L.

2017-09-01

Suprathermal oxygen and carbon atoms are produced by photochemical processes in the upper atmosphere of Mars. Due to their relatively high energies, these particle form an extended corona around Mars and can be picked up by the solar wind and emoved from the planet. The influence of an increased EUV flux, as it prevailed in the past, on the formation of the corona is studied and the corresponding loss rates are estimated. It is shown that the atmospheric loss due to the various processes varies with time and that most of the initial CO2 atmosphere is removed within the first few hundred million years after the formation of the planet. These results are important in order to better understand the atmosphere evolution of terrestrial planets.

Estimating Collisionally-Induced Escape Rates of Light Neutrals from Early Mars

NASA Astrophysics Data System (ADS)

Gacesa, M.; Zahnle, K. J.

2016-12-01

Collisions of atmospheric gases with hot oxygen atoms constitute an important non-thermal mechanism of escape of light atomic and molecular species at Mars. In this study, we present revised theoretical estimates of non-thermal escape rates of neutral O, H, He, and H2 based on recent atmospheric density profiles obtained from the NASA Mars Atmosphere and Volatile Evolution (MAVEN) mission and related theoretical models. As primary sources of hot oxygen, we consider dissociative recombination of O2+ and CO2+ molecular ions. We also consider hot oxygen atoms energized in primary and secondary collisions with energetic neutral atoms (ENAs) produced in charge-exchange of solar wind H+ and He+ ions with atmospheric gases1,2. Scattering of hot oxygen and atmospheric species of interest is modeled using fully-quantum reactive scattering formalism3. This approach allows us to construct distributions of vibrationally and rotationally excited states and predict the products' emission spectra. In addition, we estimate formation rates of excited, translationally hot hydroxyl molecules in the upper atmosphere of Mars. The escape rates are calculated from the kinetic energy distributions of the reaction products using an enhanced 1D model of the atmosphere for a range of orbital and solar parameters. Finally, by considering different scenarios, we estimate the influence of these escape mechanisms on the evolution of Mars's atmosphere throughout previous epochs and their impact on the atmospheric D/H ratio. M.G.'s research was supported by an appointment to the NASA Postdoctoral Program at the NASA Ames Research Center, administered by Universities Space Research Association under contract with NASA. 1N. Lewkow and V. Kharchenko, "Precipitation of Energetic Neutral Atoms and Escape Fluxes induced from the Mars Atmosphere", Astroph. J., 790, 98 (2014) 2M. Gacesa, N. Lewkow, and V. Kharchenko, "Non-thermal production and escape of OH from the upper atmosphere of Mars", arXiv:1607.03602 (2016) 3M. Gacesa and V. Kharchenko, "Non-thermal escape of molecular hydrogen from Mars", Geophys. Res. Lett., 39, L10203 (2012).

Ocean acidification in a geoengineering context

PubMed Central

Williamson, Phillip; Turley, Carol

2012-01-01

Fundamental changes to marine chemistry are occurring because of increasing carbon dioxide (CO2) in the atmosphere. Ocean acidity (H+ concentration) and bicarbonate ion concentrations are increasing, whereas carbonate ion concentrations are decreasing. There has already been an average pH decrease of 0.1 in the upper ocean, and continued unconstrained carbon emissions would further reduce average upper ocean pH by approximately 0.3 by 2100. Laboratory experiments, observations and projections indicate that such ocean acidification may have ecological and biogeochemical impacts that last for many thousands of years. The future magnitude of such effects will be very closely linked to atmospheric CO2; they will, therefore, depend on the success of emission reduction, and could also be constrained by geoengineering based on most carbon dioxide removal (CDR) techniques. However, some ocean-based CDR approaches would (if deployed on a climatically significant scale) re-locate acidification from the upper ocean to the seafloor or elsewhere in the ocean interior. If solar radiation management were to be the main policy response to counteract global warming, ocean acidification would continue to be driven by increases in atmospheric CO2, although with additional temperature-related effects on CO2 and CaCO3 solubility and terrestrial carbon sequestration. PMID:22869801

Inter-University Upper Atmosphere Global Observation Network (IUGONET) Metadata Database and Its Interoperability

NASA Astrophysics Data System (ADS)

Yatagai, A. I.; Iyemori, T.; Ritschel, B.; Koyama, Y.; Hori, T.; Abe, S.; Tanaka, Y.; Shinbori, A.; Umemura, N.; Sato, Y.; Yagi, M.; Ueno, S.; Hashiguchi, N. O.; Kaneda, N.; Belehaki, A.; Hapgood, M. A.

2013-12-01

The IUGONET is a Japanese program to build a metadata database for ground-based observations of the upper atmosphere [1]. The project began in 2009 with five Japanese institutions which archive data observed by radars, magnetometers, photometers, radio telescopes and helioscopes, and so on, at various altitudes from the Earth's surface to the Sun. Systems have been developed to allow searching of the above described metadata. We have been updating the system and adding new and updated metadata. The IUGONET development team adopted the SPASE metadata model [2] to describe the upper atmosphere data. This model is used as the common metadata format by the virtual observatories for solar-terrestrial physics. It includes metadata referring to each data file (called a 'Granule'), which enable a search for data files as well as data sets. Further details are described in [2] and [3]. Currently, three additional Japanese institutions are being incorporated in IUGONET. Furthermore, metadata of observations of the troposphere, taken at the observatories of the middle and upper atmosphere radar at Shigaraki and the Meteor radar in Indonesia, have been incorporated. These additions will contribute to efficient interdisciplinary scientific research. In the beginning of 2013, the registration of the 'Observatory' and 'Instrument' metadata was completed, which makes it easy to overview of the metadata database. The number of registered metadata as of the end of July, totalled 8.8 million, including 793 observatories and 878 instruments. It is important to promote interoperability and/or metadata exchange between the database development groups. A memorandum of agreement has been signed with the European Near-Earth Space Data Infrastructure for e-Science (ESPAS) project, which has similar objectives to IUGONET with regard to a framework for formal collaboration. Furthermore, observations by satellites and the International Space Station are being incorporated with a view for making/linking metadata databases. The development of effective data systems will contribute to the progress of scientific research on solar terrestrial physics, climate and the geophysical environment. Any kind of cooperation, metadata input and feedback, especially for linkage of the databases, is welcomed. References 1. Hayashi, H. et al., Inter-university Upper Atmosphere Global Observation Network (IUGONET), Data Sci. J., 12, WDS179-184, 2013. 2. King, T. et al., SPASE 2.0: A standard data model for space physics. Earth Sci. Inform. 3, 67-73, 2010, doi:10.1007/s12145-010-0053-4. 3. Hori, T., et al., Development of IUGONET metadata format and metadata management system. J. Space Sci. Info. Jpn., 105-111, 2012. (in Japanese)

Contamination and Micropropulsion Technology

DTIC Science & Technology

2012-07-01

23, 027101 (2011) Evaluation of active flow control applied to wind turbine blade section J. Renewable Sustainable Energy 2, 063101 (2010) Effect...field lines at high latitudes where solar wind electrons can readily access the upper atmosphere. The electron energy distribution in the auroral... slip behavior of n-hexadecane in large amplitude oscillatory shear flow via nonequilibrium molecular dynamic simulation J. Chem. Phys. 136, 104904

Mars, Venus, Earth and Titan UV Laboratory Aeronomy by Electron Impact

NASA Astrophysics Data System (ADS)

Malone, C. P.; Ajello, J. M.; McClintock, W. E.; Eastes, R.; Evans, J. S.; Holsclaw, G.; Schneider, N. M.; Jain, S.; Gerard, J. C. M. C.; Hoskins, A.

2017-12-01

The UV response of the Mars, Earth, Titan and Venus upper atmospheres to the solar radiation fields [solar wind and solar EUV] is the focus of the present generation of Mars, Earth, Titan and Venus missions. These missions are Mars Express (MEX), the Mars Atmosphere and Volatile Evolution Mission (MAVEN), Cassini at Titan, Global-scale Observations of the Limb and Disk (GOLD) mission for Earth and Venus Express (VEX). Each spacecraft is equipped with a UV spectrometer that senses far ultraviolet (FUV) emissions from 110-190 nm, whose dayglow intensities are proportional to three quantities:1) particle (electron, ion) fluxes, 2) the altitude distribution of species in the ionosphere: CO, CO2, O, N2 at Venus and Mars and N2, O and O2 at Titan and Earth and 3) the emission cross section for the interaction process. UV spectroscopy provides a benchmark to the present space environment and indicates pathways for removing upper atmosphere gas (e.g., water escape from Mars and Earth) or N2 escape at Titan over eons. We present a UV laboratory program that utilizes an instrument, unique in the world, at the University of Colorado that can measure excitation mechanisms by particle (electron, ion) impact and the resulting emission cross sections that include processes occurring in a planetary atmosphere, particularly the optically forbidden emissions presented by the Cameron bands, the Lyman Birge Hopfield bands and the OI 135.6 nm multiplet. There are presently uncertainties by a factor of two in the existing measurements of the emission cross section, affecting modeling of electron transport. We have utilized the MAVEN Imaging Ultraviolet Spectrograph (IUVS) engineering model which operates at moderate spectral resolution ( 0.5-1.0nm FWHM) to obtain the full vibrational spectra of the Cameron band system CO(a 3Π → X 1Σ+) from both CO direct excitation and CO2 dissociative excitation, and for the dipole-allowed Fourth Positive band system of CO, while for N2 we have studied molecular nitrogen (N2 LBH bands, a 1Πg → X 1Σg+). We have performed laboratory measurements using mono-energetic electrons in a large chamber to excite band systems by the same processes as occur at low densities in planetary atmospheres. We have ascertained vibrational structure and emission cross sections for the strongest band systems on solar system objects.

A High Speed, Radiation Hard X-Ray Imaging Spectroscometer for Planetary Investigations

NASA Technical Reports Server (NTRS)

Kraft, R. P.; Kenter, A. T.; Murray, S. S.; Martindale, A.; Pearson, J.; Gladstone, R.; Branduardi-Raymont, G.; Elsner, R.; Kimura, T.; Ezoe, Y.;

Teaching Planetary Sciences with the Master in Space Science and Technology at Universidad del País Vasco UPV/EHU: Theory and Practice works

NASA Astrophysics Data System (ADS)

Sanchez-Lavega, Agustin; Hueso, R.; Perez-Hoyos, S.

2012-10-01

The Master in Space Science and Technology is a postgraduate course at the Universidad del País Vasco in Spain (http://www.ehu.es/aula-espazio/master.html). It has two elective itineraries on space studies: scientific and technological. The scientific branch is intended for students aiming to access the PhD doctorate program in different areas of space science, among them the research of the solar system bodies. The theoretical foundations for the solar system studies are basically treated in four related matters: Astronomy and Astrophysics, Physics of the Solar System, Planetary Atmospheres, and Image Processing and Data Analysis. The practical part is developed on the one hand by analyzing planetary images obtained by different spacecrafts from public archives (e. g. PDS), and on the other hand from observations obtained by the students employing the 50 cm aperture telescope and other smaller telescopes from the Aula EspaZio Gela Observatory at the Engineering Faculty. We present the scheme of the practice works realized at the telescope to get images of the planets in different wavelengths pursuing to study the following aspects of Planetary Atmospheres: (1) Data acquisition; (2) Measurements of cloud motions to derive winds; (3) Measurement of the upper cloud reflectivity at the different wavelengths and position in the disk to retrieve the upper cloud properties and vertical structure. The theoretical foundations accompanying these practices are then introduced: atmospheric dynamics and thermodynamics, and the radiative transfer problem. Acknowledgments: This work was supported by Departamento de Promoción Económica of Diputación Foral Bizkaia through a grant to Aula EspaZio Gela at E.T.S. Ingeniería (Bilbao, Spain).

Diagnostics of electron-heated solar flare models. III - Effects of tapered loop geometry and preheating

NASA Technical Reports Server (NTRS)

Emslie, A. G.; Li, Peng; Mariska, John T.

1992-01-01

A series of hydrodynamic numerical simulations of nonthermal electron-heated solar flare atmospheres and their corresponding soft X-ray Ca XIX emission-line profiles, under the conditions of tapered flare loop geometry and/or a preheated atmosphere, is presented. The degree of tapering is parameterized by the magnetic mirror ratio, while the preheated atmosphere is parameterized by the initial upper chromospheric pressure. In a tapered flare loop, it is found that the upward motion of evaporated material is faster compared with the case where the flare loop is uniform. This is due to the diverging nozzle seen by the upflowing material. In the case where the flare atmosphere is preheated and the flare geometry is uniform, the response of the atmosphere to the electron collisional heating is slow. The upward velocity of the hydrodynamic gas is reduced due not only to the large coronal column depth, but also to the increased inertia of the overlying material. It is concluded that the only possible electron-heated scenario in which the predicted Ca XIX line profiles agree with the BCS observations is when the impulsive flare starts in a preheated dense corona.

Mars Aeronomy Explorer (MAX): Study Employing Distributed Micro-Spacecraft

NASA Technical Reports Server (NTRS)

Shotwell, Robert F.; Gray, Andrew A.; Illsley, Peter M.; Johnson, M.; Sherwood, Robert L.; Vozoff, M.; Ziemer, John K.

2005-01-01

An overview of a Mars Aeronomy Explorer (MAX) mission design study performed at NASA's Jet Propulsion Laboratory is presented herein. The mission design consists of ten micro-spacecraft orbiters launched on a Delta IV to Mars polar orbit to determine the spatial, diurnal and seasonal variation of the constituents of the Martian upper atmosphere and ionosphere over the course of one Martian year. The spacecraft are designed to allow penetration of the upper atmosphere to at least 90 km. This property coupled with orbit precession will yield knowledge of the nature of the solar wind interaction with Mars, the influence of the Mars crustal magnetic field on ionospheric processes, and the measurement of present thermal and nonthermal escape rates of atmospheric constituents. The mission design incorporates alternative design paradigms that are more appropriate for-and in some cases motivate-distributed micro-spacecraft. These design paradigms are not defined by a simple set of rules, but rather a way of thinking about the function of instruments, mission reliability/risk, and cost in a systemic framework.

A physics-based model for the ionization of samarium by the MOSC chemical releases in the upper atmosphere

NASA Astrophysics Data System (ADS)

Bernhardt, Paul A.; Siefring, Carl L.; Briczinski, Stanley J.; Viggiano, Albert; Caton, Ronald G.; Pedersen, Todd R.; Holmes, Jeffrey M.; Ard, Shaun; Shuman, Nicholas; Groves, Keith M.

2017-05-01

Atomic samarium has been injected into the neutral atmosphere for production of electron clouds that modify the ionosphere. These electron clouds may be used as high-frequency radio wave reflectors or for control of the electrodynamics of the F region. A self-consistent model for the photochemical reactions of Samarium vapor cloud released into the upper atmosphere has been developed and compared with the Metal Oxide Space Cloud (MOSC) experimental observations. The release initially produces a dense plasma cloud that that is rapidly reduced by dissociative recombination and diffusive expansion. The spectral emissions from the release cover the ultraviolet to the near infrared band with contributions from solar fluorescence of the atomic, molecular, and ionized components of the artificial density cloud. Barium releases in sunlight are more efficient than Samarium releases in sunlight for production of dense ionization clouds. Samarium may be of interest for nighttime releases but the artificial electron cloud is limited by recombination with the samarium oxide ion.

Mars dayside temperature from airglow limb profiles : comparison with in situ measurements and models

NASA Astrophysics Data System (ADS)

Gérard, Jean-Claude; Bougher, Stephen; Montmessin, Franck; Bertaux, Jean-Loup; Stiepen, A.

The thermal structure of the Mars upper atmosphere is the result of the thermal balance between heating by EUV solar radiation, infrared heating and cooling, conduction and dynamic influences such as gravity waves, planetary waves, and tides. It has been derived from observations performed from different spacecraft. These include in situ measurements of orbital drag whose strength depends on the local gas density. Atmospheric temperatures were determined from the altitude variation of the density measured in situ by the Viking landers and orbital drag measurements. Another method is based on remote sensing measurements of ultraviolet airglow limb profiles obtained over 40 years ago with spectrometers during the Mariner 6 and 7 flybys and from the Mariner 9 orbiter. Comparisons with model calculations indicate that they both reflect the CO_2 scale height from which atmospheric temperatures have been deduced. Upper atmospheric temperatures varying over the wide range 270-445 K, with a mean value of 325 K were deduced from the topside scale height of the airglow vertical profile. We present an analysis of limb profiles of the CO Cameron (a(3) Pi-X(1) Sigma(+) ) and CO_2(+) doublet (B(2) Sigma_u(+) - X(2) PiΠ_g) airglows observed with the SPICAM instrument on board Mars Express. We show that the temperature in the Mars thermosphere is very variable with a mean value of 270 K, but values ranging between 150 and 400 K have been observed. These values are compared to earlier determinations and model predictions. No clear dependence on solar zenith angle, latitude or season is apparent. Similarly, exospheric variations with F10.7 in the SPICAM airglow dataset are small over the solar minimum to moderate conditions sampled by Mars Express since 2005. We conclude that an unidentified process is the cause of the large observed temperature variability, which dominates the other sources of temperature variations.

Nature of the Venus thermosphere derived from satellite drag measurements (solicited paper)

NASA Astrophysics Data System (ADS)

Keating, G.; Theriot, M.; Bougher, S.

2008-09-01

From drag measurements obtained by Pioneer Venus and Magellan, the Venus upper atmosphere was discovered to be much colder than Earth's, even though Venus is much closer to the Sun than the Earth. On the dayside, exospheric temperatures are near 300K compared to Earth's of near 1200K [1]. This is thought to result principally from 15 micron excitation of carbon dioxide by atomic oxygen resulting in very strong 15 micron emission to space, cooling off the upper atmosphere [2]. On the nightside the Venus upper atmosphere is near 100K [3], compared to Earth where temperatures are near 900K. The nightside Venus temperatures drop with altitude contrary to a thermosphere where temperatures rise with altitude. As a result, the very cold nightside is called a "cryosphere" rather than a thermosphere. This is the first cryosphere discovered in the solar system [1]. Temperatures sharply drop near the terminator. Apparently, heat is somehow blocked near the terminator from being significantly transported to the nightside [4]. Recently, drag studies were performed on a number of Earth satellites to establish whether the rise of carbon dioxide on Earth was cooling the Earth's thermosphere similar to the dayside of Venus. Keating et al. [5] discovered that a 10 percent drop in density near 350km at solar minimum occurred globally over a period of 20 years with a 10 per cent rise in carbon dioxide. This should result in about a factor of 2 decline in density from 1976 values, by the end of the 21st century brought on by thermospheric cooling. Subsequent studies have confirmed these results. Thus we are beginning to see the cooling of Earth's upper atmosphere apparently from the same process cooling the Venus thermosphere. Fig. 1 VIRA Exospheric Temperatures Atmospheric drag data from the Pioneer Venus Orbiter and Magellan were combined to generate an improved version of the Venus International Reference Atmosphere (VIRA) [6], [7]. A "fountain effect" was discovered where the atmosphere rises on the dayside producing adiabatic cooling and drops on the nightside producing some adiabatic heating. (See figure 1). The thermosphere was discovered from drag measurements to respond to the near 27-day period of the rotating Sun, for which regions of maximum solar activity reappear every 27 days. The increased euv emission from active regions increased temperatures and thermospheric density, (See Figure 2). Fig. 2 Exospheric Temperatures Compared to 10.7cm Solar Index Second diurnal survey (12/5/79 - 3/6/80) Pioneer Venus Orbiter measurements (OAD) 11 day running means [2] Estimates were also made of the response to the 11- year Solar Cycle by combining the Pioneer Venus and Magellan data. Dayside exospheric temperatures changed about 80K over the solar cycle, [8]. Earlier estimates of temperature change gave 70K based on Lyman alpha measurements. The responses to solar variability were much weaker than on Earth due apparently to the much stronger O/CO2 cooling on Venus which tended to act as a thermostat on thermospheric temperatures. Another discovery from drag measurements was the 4 to 5 day oscillation of the Venus thermosphere [3], (See figure 3). These oscillations are interpreted as resulting from the 4-day super-rotation of the atmosphere near the cloud tops. Other indications of the super-rotation of the thermosphere come from displacement of the helium bulge and atomic hydrogen bulge from midnight to near 4AM. Fig. 3 Four to Five Day Oscillations in Thermospheric Densities Magellan 1992. During 2008, the Venus Express periapsis will be dropped from 250km down to approximately 180km to allow drag measurements to be made in the North Polar Region, [9]. Drag measurements above 200km have already been obtained from both Pioneer Venus and Magellan so measurements near 180km should be accurate. In 2009, the periapsis may be decreased to a lower altitude allowing accelerometer measurements to be obtained of drag as a function of altitude, to determine density, scale height, inferred temperature, pressure, and other parameters as a function of altitude. The risk involved in the orbital decay and accelerometer measurements is minimal. We have not lost any spacecraft orbiting Venus or Mars due to unexpected thermospheric drag effects in over 30 years. The Venus Express accelerometer drag experiment is very similar to accelerometer experiments aboard Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter which orbit Mars. The Venus Express drag measurements of the polar region will allow a global empirical model of the thermosphere to emerge. Previous drag measurements have been made principally near the equator. The experiment may help us understand on a global scale, tides, winds, gravity waves, planetary waves, and the damping of waves. Comparisons will be made between low and high latitude results; between the middle and upper atmosphere; and with other instruments that provide information from current and previous measurements. The character of the sharp temperature gradient near the day/night terminator needs to be studied at all latitudes. The cryosphere we discovered on the nightside needs to be studied at high latitudes. The rotating vortex dipole over the North Pole surrounded by a colder "collar" needs to be analyzed to identify how wave activity extends into the polar thermosphere. We have already discovered super-rotation in the equatorial thermosphere, but we need to study 4-day super-rotation at higher latitudes to obtain a global picture of the thermosphere. The super-rotation may affect escape rates and the evolution of the atmosphere. References: [1] Keating, G. M., et al: Venus Thermosphere and Exosphere: First Satellite Drag Measurements of an Extraterrestrial Atmosphere. Science, Vol. 203, No. 4382, 772-774, Feb. 23, 1979. [2] Keating, G. M. and Bougher, S.W.: Isolation of Major Venus Cooling Mechanism and Implications for Earth and Mars, Journal of Geophysical Research, Vol. 97, 4189-4197, 1992. [3] Keating, G.M.; Taylor, F.W.; Nicholson, J. V. II; and Hinson, E.W. : Short-Term Cyclic Variations and Diurnal Variations of the Venus Upper Atmosphere, Science, Vol. 205, No. 4401, 62-64, July 6, 1979. [4] Bougher, S. W.; Dickinson, R. E.; Ridley, E. C.; Roble, R. G.; Nagy, A. F.; and Cravens, T. E.: Venus mesosphere and thermosphere, II, Global circulation, temperature, and density variations, Icarus, Vol. 68, 284-312, 1986. [5] Keating, G. M. et al.: Evidence of Long-Term Global Decline in the Earth's Thermospheric Densities Apparently Related to Anthropogenic Effects, Geophysical Research Letters, Vol. 27, No. 10, 1522-1526, 2000. [6] Keating, G. M. et al.: Models of Venus Neutral Upper Atmosphere Structure and Composition: The Venus International Reference Atmosphere (Edited by A. L. Kliore, V. I. Moros, and G. M. Keating) Advances in Space Research, Vol. 5, No. 11, 117-171,1985. [7] Keating, G. M.; Hsu, N.C., and Lyu, J.: Improved Thermospheric Model for the Venus International Reference Atmosphere, Proceedings of the 31st Scientific Assembly of COSPAR, Birmingham, England, 139, 1996 (Invited) [8] Keating, G. M. and Hsu, N. C.: The Venus Atmospheric Response to Solar Cycle Variations, Geophysical Research Letters, Vol. 20, 2751-2754, 1993. [9] Keating, G.M. et al: Future drag measurements from Venus Express. Adv

Hot oxygen escape from Mars: Simple scaling with solar EUV irradiance

NASA Astrophysics Data System (ADS)

Cravens, T. E.; Rahmati, A.; Fox, Jane L.; Lillis, R.; Bougher, S.; Luhmann, J.; Sakai, S.; Deighan, J.; Lee, Yuni; Combi, M.; Jakosky, B.

2017-01-01

The evolution of the atmosphere of Mars and the loss of volatiles over the lifetime of the solar system is a key topic in planetary science. An important loss process for atomic species, such as oxygen, is ionospheric photochemical escape. Dissociative recombination of O2+ ions (the major ion species) produces fast oxygen atoms, some of which can escape from the planet. Many theoretical hot O models have been constructed over the years, although a number of uncertainties are present in these models, particularly concerning the elastic cross sections of O atoms with CO2. Recently, the Mars Atmosphere and Volatile Evolution mission has been rapidly improving our understanding of the upper atmosphere and ionosphere of Mars and its interaction with the external environment (e.g., solar wind), allowing a new assessment of this important loss process. The purpose of the current paper is to take a simple analytical approach to the oxygen escape problem in order to (1) study the role that variations in solar radiation or solar wind fluxes could have on escape in a transparent fashion and (2) isolate the effects of uncertainties in oxygen cross sections on the derived oxygen escape rates. In agreement with several more elaborate numerical models, we find that the escape flux is directly proportional to the incident solar extreme ultraviolet irradiance and is inversely proportional to the backscatter elastic cross section. The amount of O lost due to ion transport in the topside ionosphere is found to be about 5-10% of the total.

Space observations of aerosols and ozone; Proceedings of the Topical Meeting, Ottawa, Canada, May 16-June 2, 1982

NASA Technical Reports Server (NTRS)

Mccormick, M. P. (Editor); Lovill, J. E.

1982-01-01

The measurement of aerosols from space is discussed, taking into account the role of aerosols in climate, instrumentation and further measurement systems, retrieval procedures, measurements and observations, ground truth measurements, and effects on remote sensing and on climate. Aspects of ozone variability in the middle atmosphere are explored, giving attention to the quasi-biennial oscillation in equatorial stratospheric temperatures and total ozone, global pictures on the ozone field from high altitudes from DE-1, measurements of atmospheric ozone from aircraft and from balloons, a mesospheric ozone profile at sunset, periodic and aperiodic ozone variations in the middle and upper stratosphere, solar eclipse induced variations in mesospheric ozone concentrations, and solar UV and ozone balloon measurements. The determination of aerosol optical depth is considered along with a method for estimating cross radiance.

Dynamical buoyancy of hydrodynamic eddies. [in solar atmosphere

NASA Technical Reports Server (NTRS)

Parker, E. N.

1991-01-01

The dynamical pressure reduction within a vortex tube produces both a tension along the tube and a general buoyancy, analogous to magnetic flux tubes. The dynamical buoyancy causes convective cells to rise at speeds comparable to the rms fluid velocity within the cell. Consequently, the convective cells in a stratified atmosphere are more active than indicated by the standard anelastic approximation. The coherent convective cells at each level actively crowd upward into the convective cells above, elbowing weaker cells out of the way and flattening themselves and others against the upper surface of the convective region. These effects can be seen in the recent SOUP observations of the solar granulation. Deeper in the convective zone the inhomogeneity of the buoyancy may explain the random character of the convective motions that turns up in recent numerical simulations.

The radiative impact of cumulus cloudiness in a general circulation model

NASA Technical Reports Server (NTRS)

Moeng, C. H.; Randall, D. A.

1982-01-01

The effect of cumulus cloudiness on the radiational heating and, on other aspects of the climate were simulated by the GLAS Climate Model. An experiment in which the cumulus cloudiness is neglected completely for purposes of the solar and terrestrial radiation parameterizations was performed. The results are compared with those of a control run, in which 100% cumulus cloud cover is assumed. The net solar radiation input into the Earth atmosphere system is more realistic in the experiment, and the model's underprediction of the global mean outgoing thermal radiation at the top of the atmosphere is reduced. The results suggest that there is a positive feedback between cumulus convection and the radiation field. The upper troposphere is warmer in the experiment, the surface air temperature increases over land, and the thermal lows over the continents intensity.

Global upper ocean heat storage response to radiative forcing from changing solar irradiance and increasing greenhouse gas/aerosol concentrations

NASA Astrophysics Data System (ADS)

White, Warren B.; Cayan, Daniel R.; Lean, Judith

1998-09-01

We constructed gridded fields of diabatic heat storage changes in the upper ocean from 20°S to 60°N from historical temperature profiles collected from 1955 to 1996. We filtered these 42 year records for periods of 8 to 15 years and 15 to 30 years, producing depth-weighted vertical average temperature (DVT) changes from the sea surface to the top of the main pycnocline. Basin and global averages of these DVT changes reveal decadal and interdecadal variability in phase across the Indian, Pacific, Atlantic, and Global Oceans, each significantly correlated with changing surface solar radiative forcing at a lag of 0+/-2 years. Decadal and interdecadal changes in global average DVT are 0.06°+/-0.01°K and 0.04°K+/-0.01°K, respectively, the same as those expected from consideration of the Stefan-Boltzmann radiation balance (i.e., 0.3°K per Wm-2) in response to 0.1% changes in surface solar radiative forcing of 0.2 Wm-2 and 0.15 Wm-2, respectively. Global spatial patterns of DVT changes are similar to temperature changes simulated in coupled ocean-atmosphere models, suggesting that natural modes of Earth's variability are phase-locked to the solar irradiance cycle. A trend in global average DVT of 0.15°K over this 42 year record cannot be explained by changing surface solar radiative forcing. But when we consider the 0.5 Wm-2 increase in surface radiative forcing estimated from the increase in atmospheric greenhouse gas and aerosol (GGA) concentrations over this period [Intergovernmental Panel on Climate Change, 1995], the Stefan-Boltzmann radiation balance yields this observed change. Moreover, the sum of solar and GGA surface radiative forcing can explain the relatively sharp increase in global and basin average DVT in the late 1970's.

Study of long term effect of Solar UV and X-ray radiation on the VLF signals

NASA Astrophysics Data System (ADS)

Ray, Suman; Chakrabarti, Sandip Kumar; Sanki, Dipak

2016-07-01

Very Low Frequency (VLF) is one of the bands of Radio waves having frequencies lying between 3-30 KHz, with wavelengths 100-10 Km. It propagates through the Earth-ionosphere wave-guide which is formed by lower part of the ionosphere and upper part of Earth's surface. Ionosphere is the ionized component of upper atmosphere. In the present work, we have studied the long term effect of the high energy solar UV and X-ray radiation on the VLF signals. We have analyzed the VLF signal transmitted at 24 KHz from NAA (Cutler, Maine) and received at Moore Observatory in Brownsboro, Kentucky. Also we have collected X-ray and UV data to study the long term effect of UV and X-ray radiation on the VLF signal. We have analyzed the VLF signal for 2007 to 2015. We calculate the average diurnal peak amplitude of the VLF signal for each day and compare it with the UV and X-ray solar radiation. We found that the correlation coefficient of diurnal peak VLF signal amplitude with both solar X-ray and UV radiation is 0.7 indicating a strong correlation between these two phenomena.

The Influence of Large Solar Proton Events on the Atmosphere

NASA Technical Reports Server (NTRS)

Jackman, Charles H.

2012-01-01

Solar proton events (SPEs) can cause changes in constituents in the Earth s polar middle atmosphere. A number of large SPEs have occurred over the past 50 years and tend to happen most frequently near solar maximum. The highly energetic protons cause ionizations, excitations, dissociations, and dissociative ionizations of the background constituents. Complicated ion chemistry leads to HOx (H, OH, HO2) production and dissociation of N2 leads to NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2) production. Both the HOx and NOy increases can result in changes to ozone in the stratosphere and mesosphere. The HOx increases lead to short-lived (days) ozone decreases in the mesosphere and upper stratosphere. The NOy increases lead to long-lived (several months) stratospheric ozone changes because of the long lifetime of NOy constituents in this region. UARS HALogen Occultation Experiment (HALOE) instrument observations showed SPE-caused polar stratospheric NOx (NO+NO2) increases over 10 ppbv in September 2000 due to the very large SPE of July 2000, which are reasonably well simulated with the Whole Atmosphere Community Climate Model (WACCM). WACCM-computed SPE-caused polar stratospheric ozone decreases >10% continued for up to 5 months past the largest events in the past 50 years, however, SPE-caused total ozone changes were not found to be statistically significant. Small polar middle atmospheric temperature changes of <4 K have also been predicted to occur as a result of the larger SPEs. The polar atmospheric effects of large SPEs during solar cycle 23 and 24 will be emphasized in this presentation.

Middle Atmospheric Changes Caused by the January and March 2012 Solar Proton Events

NASA Astrophysics Data System (ADS)

Jackman, Charles; Bernath, Peter; Fleming, Eric; Randall, Cora; Harvey, V. Lynn; Funke, Bernd; Lopez-Puertas, Manuel; Wang, Shuhui

Solar proton events (SPEs) can cause changes in constituents in the Earth’s polar middle atmosphere. The 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic protons caused ionizations, excitations, dissociations, and dissociative ionizations of the background constituents. Complicated ion chemistry led to HOx (H, OH, HO2) production and dissociation of N2 leads to NOy (N, NO, NO2, NO3, N2O5, HNO2, HNO3, HO2NO2, ClONO2, BrONO2) production. Both the HOx and NOy increases resulted in changes to ozone in the stratosphere and mesosphere. The HOx increases led to short-lived (~days) ozone decreases in the mesosphere and upper stratosphere. These short-lived impacts on the atmosphere will be illustrated using Aura Microwave Limb Sounder (MLS) observations of the peroxy radical, HO2, and ozone. The longer-lived (~several months) atmospheric changes were coupled with the SPE-caused NOy increases. We computed a NOy production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which placed these SPE periods among the 12 largest in the past 50 yrs. SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE) and the Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instruments observations of NO and NO2 will be used to illustrate these longer-lived SPE-caused changes. The satellite observations will be compared with Goddard Space Flight Center (GSFC) two-dimensional (2-D) model and Global Modeling Initiative three-dimensional chemistry and transport model predictions. Polar total ozone reductions were predicted to be a maximum of 1.5 percent in 2012 due to these SPEs.

Atmospheric Responses from Radiosonde Observations of the 2017 Total Solar Eclipse

NASA Astrophysics Data System (ADS)

Fowler, J.

2017-12-01

The Atmospheric Responses from Radiosonde Observations project during the August 21st, 2017 Total Solar Eclipse was to observe the atmospheric response under the shadow of the Moon using both research and operational earth science instruments run primarily by undergraduate students not formally trained in atmospheric science. During the eclipse, approximately 15 teams across the path of totality launched radiosonde balloon platforms in very rapid, serial sonde deployment. Our strategy was to combine a dense ground observation network with multiple radiosonde sites, located within and along the margins of the path of totality. This can demonstrate how dense observation networks leveraged among various programs can "fill the gaps" in data sparse regions allowing research ideas and questions that previously could not be approached with courser resolution data and improving the scientific understanding and prediction of geophysical and hazardous phenomenon. The core scientific objectives are (1) to make high-resolution surface and upper air observations in several sites along the eclipse path (2) to quantitatively study atmospheric responses to the rapid disappearance of the Sun across the United States, and (3) to assess the performance of high-resolution weather forecasting models in simulating the observed response. Such a scientific campaign, especially unique during a total solar eclipse, provides a rare but life-altering opportunity to attract and enable next-generation of observational scientists. It was an ideal "laboratory" for graduate, undergraduate, citizen scientists and k-12 students and staff to learn, explore and research in STEM.

Dynamics of Venus Upper Atmosphere from Infrared Heterodyne Spectroscopy of CO2

NASA Astrophysics Data System (ADS)

Sornig, Manuela; Sonnabend, G.; Kroetz, P. J.; Stupar, D.; Schieder, R. T.; Sandor, B.; Clancy, T.

2009-09-01

Wind velocities in the upper atmosphere of Venus can be determined from Doppler-shifts of narrow non-LTE emission lines of CO2 at 10 µm with an precision of up to 10 m/s using infrared heterodyne spectroscopy. Such observations address a narrow altitude region in the upper atmosphere of Venus around 110 km. At the University of Cologne we developed a Tunable Infrared Heterodyne Spectrometer (THIS) capable of accomplishing such ground-based measurements of planetary atmospheres. Beside high spectral resolution (R>107) this method also guarantees high spatial resolution on the planet (FOV of 1.7 arcsec on an apparent diameter of Venus of 20 arcsec using the McMath-Pierce-Solar Telescope on Kitt Peak). Over the last two years we observed wind velocities with THIS at several characteristic orbital positions of Venus. In May and November 2007 Venus was at its maximum eastern and western elongation, respectively. This specific observing geometry with an illumination of about 50% of the apparent planetary disk allows us to detect dominantly the superrotation component in Venus upper atmosphere. So far results indicate surprisingly low wind velocities of a few tens of m/s with almost no wind at the equator and highest values at mid latitudes. Observations close to inferior conjunction have been accomplished in March and April 2009. This observing geometry gives wind velocities consisting of a combination of the superrotation and the SS-AS flow close to the terminator. Data analysis is still ongoing but first analysis indicate a higher wind velocity than found in the results from maximum elongation. We are going to present data and results from these runs as well as results from a first coordinated observation between our infrared group and JCMT sub-mm observations in March 2009.

Acquisition and Early Losses of Rare Gases from the Deep Earth

NASA Technical Reports Server (NTRS)

Porcelli, D.; Cassen, P.; Woolum, D.; Wasserburg, G. J.

1998-01-01

Direct observations show that the deep Earth contains rare gases of solar composition distinct from those in the atmosphere. We examine the implications of mantle rare gas characteristics on acquisition of rare gases from the solar nebula and subsequent losses due to a large impact. Deep mantle rare gas concentrations and isotopic compositions can be obtained from a model of transport and distribution of mantle rare gases. This model assumes the lower mantle closed early, while the upper mantle is open to subduction from the atmosphere and mass transfer from the lower mantle. Constraints are derived that can be incorporated into models for terrestrial volatile acquisition: (1) Calculated lower-mantle Xe-isotopic ratios indicate that the fraction of radiogenic Xe produced by I-129 and Pu-244 during the first about 10(exp 8) yr was lost, a conclusion also drawn for atmospheric Xe. Thus, either the Earth was made from materials that had lost >99% of rare gases about (0.7-2) x 10(exp 8) yr after the solar system formed, or gases were then lost from the fully formed Earth. (2) Concentrations of 3He and 20Ne in the lower mantle were established after these losses. (3) Neon-isotopic data indicates that mantle Ne has solar composition. The model allows for solar Ar/Ne and Xe/Ne in the lower mantle if a dominant fraction of upper mantle Ar and Xe are subduction-derived. If Earth formed in the presence of the solar nebula, it could have been melted by accretional energy and the blanketing effect of a massive, nebula-derived atmosphere. Gases from this atmosphere would have been sequestered within the molten Earth by dissolution at the surface and downward mixing. It was found that too much Ne would be dissolved in the Earth unless the atmosphere began to escape when the Earth was only partially assembled. Here we consider conditions required to initially dissolve sufficient rare gases to account for the present lower mantle concentrations after subsequent losses at 10(exp 8) yr. It is assumed that equilibration of the atmosphere with a thoroughly molten mantle was rapid, so that initial abundances of gases retained in any mantle layer reflected surface conditions when the layer solidified. For subsequent gas loss of 99.5% and typical solubility coefficients, a total pressure of 100 atm was required for an atmosphere of solar composition. Calculations of the pressure at the base of a primordial atmosphere indicate that this value might be exceeded by an order of magnitude or more for an atmosphere supported by accretional energy. Surface temperatures of about 4000 K would have been produced, probably high enough to melt the deep mantle. Initial distributions of retained rare gases would then be determined by the history of surface pressure and temperature during mantle cooling and solidification, i.e., the coupled cooling of Earth and atmosphere. The Earth's thermal state was determined by its surface temperature and the efficiency of convection in the molten mantle, estimated to be sufficient to maintain an adiabatic gradient. Because the melting curve is steeper than the adiabat, solidification of the mantle proceeded outward from the interior. Incorporation of atmospheric gases in the mantle therefore occurred over a range in surface temperature of a few thousand degrees Kelvin. The thermal state of the atmosphere was controlled by total luminosity of the Earth (energy) released by accreting planetesimals and the cooling Earth), nebular temperature and pressure, and atmospheric opacity. The energy released by accretion declined with time as did nebular pressure. Analytical solutions for an idealized (constant opacity radiative atmosphere show that declining energy sources under constant nebular conditions result in slowly diminishing surface temperature but dramatically increasing surface pressure. For such an atmosphere with declining nebular pressure but constant total luminosity, surface pressure decreases gradually with decreasing temperaure. A decline in accretion luminosity might be compensated by energy released as the mantle cools for about 10(exp 5) year, after which luminosity must decline. The total complement of dissolved rare gases will depend on the particular evolutionary path determined by the declining accretional luminosity, the Earth thermal history, removal of the nebula, and opacity variations of the atmosphere. Models for these coupled evolutionary histories for Earth's acquisition of nebular-derived noble gases are in progress. The later losses required at about 10(exp 8) yr (depleting the interior concentrations of the sequestered solar gases by a factor of > 100) were presumably related to the major impact in which the Moon formed.

Science Enhancements by the MAVEN Participating Scientists

NASA Technical Reports Server (NTRS)

Grebowsky, J.; Fast, K.; Talaat, E.; Combi, M.; Crary, F.; England, S.; Ma, Y.; Mendillo, M.; Rosenblatt, P.; Seki, K.

2014-01-01

NASA implemented a Participating Scientist Program and released a solicitation for the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) proposals on February 14, 2013. After a NASA peer review panel evaluated the proposals, NASA Headquarters selected nine on June 12, 2013. The program's intent is to enhance the science return from the mission by including new investigations that broaden and/or complement the baseline investigations, while still addressing key science goals. The selections cover a broad range of science investigations. Included are: a patching of a 3D exosphere model to an improved global ionosphere-thermosphere model to study the generation of the exosphere and calculate the escape rates; the addition of a focused study of upper atmosphere variability and waves; improvement of a multi-fluid magnetohydrodynamic model that will be adjusted according to MAVEN observations to enhance the understanding of the solar-wind plasma interaction; a global study of the state of the ionosphere; folding MAVEN measurements into the Mars International Reference Ionosphere under development; quantification of atmospheric loss by pick-up using ion cyclotron wave observations; the reconciliation of remote and in situ observations of the upper atmosphere; the application of precise orbit determination of the spacecraft to measure upper atmospheric density and in conjunction with other Mars missions improve the static gravity field model of Mars; and an integrated ion/neutral study of ionospheric flows and resultant heavy ion escape. Descriptions of each of these investigations are given showing how each adds to and fits seamlessly into MAVEN mission science design.

Science Enhancements by the MAVEN Participating Scientists

NASA Astrophysics Data System (ADS)

Grebowsky, J.; Fast, K.; Talaat, E.; Combi, M.; Crary, F.; England, S.; Ma, Y.; Mendillo, M.; Rosenblatt, P.; Seki, K.; Stevens, M.; Withers, P.

2015-12-01

NASA implemented a Participating Scientist Program and released a solicitation for the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) proposals on February 14, 2013. After a NASA peer review panel evaluated the proposals, NASA Headquarters selected nine on June 12, 2013. The program's intent is to enhance the science return from the mission by including new investigations that broaden and/or complement the baseline investigations, while still addressing key science goals. The selections cover a broad range of science investigations. Included are: a patching of a 3D exosphere model to an improved global ionosphere-thermosphere model to study the generation of the exosphere and calculate the escape rates; the addition of a focused study of upper atmosphere variability and waves; improvement of a multi-fluid magnetohydrodynamic model that will be adjusted according to MAVEN observations to enhance the understanding of the solar-wind plasma interaction; a global study of the state of the ionosphere; folding MAVEN measurements into the Mars International Reference Ionosphere under development; quantification of atmospheric loss by pick-up using ion cyclotron wave observations; the reconciliation of remote and in situ observations of the upper atmosphere; the application of precise orbit determination of the spacecraft to measure upper atmospheric density and in conjunction with other Mars missions improve the static gravity field model of Mars; and an integrated ion/neutral study of ionospheric flows and resultant heavy ion escape. Descriptions of each of these investigations are given showing how each adds to and fits seamlessly into MAVEN mission science design.

Solar Effects on Climate and the Maunder Minimum: Minimum Certainty

NASA Technical Reports Server (NTRS)

Rind, David

2003-01-01

The current state of our understanding of solar effects on climate is reviewed. As an example of the relevant issues, the climate during the Maunder Minimum is compared with current conditions in GCM simulations that include a full stratosphere and parameterized ozone response to solar spectral irradiance variability and trace gas changes. The GISS Global Climate/Middle Atmosphere Model coupled to a q-flux/mixed layer model is used for the simulations, which begin in 1500 and extend to the present. Experiments were made to investigate the effect of total versus spectrally-varying solar irradiance changes; spectrally-varying solar irradiance changes on the stratospheric ozone/climate response with both pre-industrial and present trace gases; and the impact on climate and stratospheric ozone of the preindustrial trace gases and aerosols by themselves. The results showed that: (1) the Maunder Minimum cooling relative to today was primarily associated with reduced anthropogenic radiative forcing, although the solar reduction added 40% to the overall cooling. There is no obvious distinguishing surface climate pattern between the two forcings. (2)The global and tropical response was greater than 1 C, in a model with a sensitivity of 1.2 C per W m-2. To reproduce recent low-end estimates would require a sensitivity 1/4 as large. (3) The global surface temperature change was similar when using the total and spectral irradiance prescriptions, although the tropical response was somewhat greater with the former, and the stratospheric response greater with the latter. (4) Most experiments produce a relative negative phase of the NAO/AO during the Maunder Minimum, with both solar and anthropogenic forcing equally capable, associated with the tropical cooling and relative poleward EP flux refraction. (5) A full stratosphere appeared to be necessary for the negative AO/NAO phase, as was the case with this model for global warming experiments, unless the cooling was very large, while the ozone response played a minor role and did not influence surface temperature significantly. (6) Stratospheric ozone was most affected by the difference between present day and preindustrial atmospheric composition and chemistry, with increases in the upper and lower stratosphere during the Maunder Minimum. While the estimated UV reduction led to ozone decreases, this was generally less important than the anthropogenic effect except in the upper middle stratosphere, as judged by two different ozone photochemistry schemes. (7) The effect of the reduced solar irradiance on stratospheric ozone and on climate was similar in Maunder Minimum and current atmospheric conditions.

Multi-fluid MHD Study of the Solar Wind Interaction with Mars' Upper Atmosphere during the 2015 March 8th ICME Event

NASA Astrophysics Data System (ADS)

Dong, C.; Ma, Y.; Bougher, S. W.; Toth, G.; Nagy, A. F.; Halekas, J. S.; Dong, Y.; Curry, S.; Luhmann, J. G.; Brain, D. A.; Connerney, J. E. P.; Espley, J. R.; Mahaffy, P. R.; Benna, M.; McFadden, J. P.; Mitchell, D. L.; DiBraccio, G. A.; Lillis, R. J.; Jakosky, B. M.; Grebowsky, J. M.

2015-12-01

The 3-D Mars multi-fluid BATS-R-US MHD code is used to study the solar wind interaction with the Martian upper atmosphere during the 2015 March 8th interplanetary coronal mass ejection (ICME). We studied four steady-state cases, corresponding to three major ICME phases: pre-ICME phase (Case 1), sheath phase (Cases 2--3), and ejecta phase (Case 4). Detailed data-model comparisons demonstrate that the simulation results are in good agreement with Mars Atmosphere and Volatile EvolutioN (MAVEN) measurements, indicating that the multi-fluid MHD model can reproduce most of the features observed by MAVEN, thus providing confidence in the estimate of ion escape rates from its calculation. The total ion escape rate is increased by an order of magnitude, from 2.05×1024 s-1 (pre-ICME phase) to 2.25×1025 s-1 (ICME sheath phase), during this time period. The calculated ion escape rates were used to examine the relative importance of the two major ion loss channels from the planet: energetic pickup ion loss through the dayside plume and cold ionospheric ion loss through the nightside plasma wake region. We found that the energetic pickup ions escaping from the dayside plume could be as much as ~23% of the total ion loss prior to the ICME arrival. Interestingly, the tailward ion escape rate is significantly increased at the ejecta phase, leading to a reduction of the dayside ion escape to ~5% of the total ion loss. Under such circumstance, the cold ionospheric ions escaping from the plasma wake comprise the majority of the ion loss from the planet. Furthermore, by comparing four simulation results along the same MAVEN orbit, we note that there is no significant variation in the Martian lower ionosphere. Finally, both bow shock and magnetic pileup boundary (BS, MPB) locations are decreased from (1.2 RMars, 1.57 RMars) at the pre-ICME phase to (1.16 RMars, 1.47 RMars) respectively during the sheath phase along the dayside Sun-Mars line. MAVEN has provided a great opportunity to study the evolution of the Martian atmosphere and climate over its history. A large quantity of useful data has been returned for future studies. These kinds of data-model comparisons can help the community to better understand the Martian upper atmosphere response to the (extreme) variation in the solar wind and its interplanetary environment from a global perspective.

Numerical simulation of the circulation of the atmosphere of Titan

NASA Technical Reports Server (NTRS)

Hourdin, F.; Levan, P.; Talagrand, O.; Courtin, Regis; Gautier, Daniel; Mckay, Christopher P.

1992-01-01

A three dimensional General Circulation Model (GCM) of Titan's atmosphere is described. Initial results obtained with an economical two dimensional (2D) axisymmetric version of the model presented a strong superrotation in the upper stratosphere. Because of this result, a more general numerical study of superrotation was started with a somewhat different version of the GCM. It appears that for a slowly rotating planet which strongly absorbs solar radiation, circulation is dominated by global equator to pole Hadley circulation and strong superrotation. The theoretical study of this superrotation is discussed. It is also shown that 2D simulations systemically lead to instabilities which make 2D models poorly adapted to numerical simulation of Titan's (or Venus) atmosphere.

IMPACT: Integrated Modeling of Perturbations in Atmospheres for Conjunction Tracking

NASA Astrophysics Data System (ADS)

Koller, J.; Brennan, S.; Godinez, H. C.; Higdon, D. M.; Klimenko, A.; Larsen, B.; Lawrence, E.; Linares, R.; McLaughlin, C. A.; Mehta, P. M.; Palmer, D.; Ridley, A. J.; Shoemaker, M.; Sutton, E.; Thompson, D.; Walker, A.; Wohlberg, B.

2013-12-01

Low-Earth orbiting satellites suffer from atmospheric drag due to thermospheric density which changes on the order of several magnitudes especially during space weather events. Solar flares, precipitating particles and ionospheric currents cause the upper atmosphere to heat up, redistribute, and cool again. These processes are intrinsically included in empirical models, e.g. MSIS and Jacchia-Bowman type models. However, sensitivity analysis has shown that atmospheric drag has the highest influence on satellite conjunction analysis and empirical model still do not adequately represent a desired accuracy. Space debris and collision avoidance have become an increasingly operational reality. It is paramount to accurately predict satellite orbits and include drag effect driven by space weather. The IMPACT project (Integrated Modeling of Perturbations in Atmospheres for Conjunction Tracking), funded with over $5 Million by the Los Alamos Laboratory Directed Research and Development office, has the goal to develop an integrated system of atmospheric drag modeling, orbit propagation, and conjunction analysis with detailed uncertainty quantification to address the space debris and collision avoidance problem. Now with over two years into the project, we have developed an integrated solution combining physics-based density modeling of the upper atmosphere between 120-700 km altitude, satellite drag forecasting for quiet and disturbed geomagnetic conditions, and conjunction analysis with non-Gaussian uncertainty quantification. We are employing several novel approaches including a unique observational sensor developed at Los Alamos; machine learning with a support-vector machine approach of the coupling between solar drivers of the upper atmosphere and satellite drag; rigorous data assimilative modeling using a physics-based approach instead of empirical modeling of the thermosphere; and a computed-tomography method for extracting temporal maps of thermospheric densities using ground based observations. The developed IMPACT framework is an open research framework enabling the exchange and testing of a variety of atmospheric density models, orbital propagators, drag coefficient models, ground based observations, etc. and study their effect on conjunctions and uncertainty predictions. The framework is based on a modern service-oriented architecture controlled by a web interface and providing 3D visualizations. The goal of this project is to revolutionize the ability to monitor and track space objects during highly disturbed space weather conditions, provide suitable forecasts for satellite drag conditions and conjunction analysis, and enable the exchange of models, codes, and data in an open research environment. We will present capabilities and results of the IMPACT framework including a demo of the control interface and visualizations.

Comparison of dayside current layers in Venus' ionosphere and earth's equatorial electrojet

NASA Technical Reports Server (NTRS)

Cole, Keith D.

1993-01-01

The major physical aspects of the equatorial electrojet of Earth and the dayside ionospheric current layers of Venus are compared, viz., the electric current intensity and total current, roles of electric field, pressure and gravity, diffusion time scales, and the Bernouille effect. The largest potential differences, of the order of 10 volts, horizontally across the dayside ionosphere of Venus, have important implications for possible dynamo action in the Venus ionosphere and the application of an electric field from the lower atmosphere or from the solar wind. An upper limit to the horizontal scale of vertical magnetic fields in the Venus ionosphere is estimated thereby for the first time. New upper limits on the velocity in, and thickness of, a possible S layer at Venus are presented. If an S layer exists, it is only for extreme conditions of the solar wind. A mechanism for formation of magnetic ropes in the Venus ionosphere is also proposed.

NASA’s Solar Dynamics Observatory Captured Trio of Solar Flares April 2-3

NASA Image and Video Library

2017-12-08

The sun emitted a trio of mid-level solar flares on April 2-3, 2017. The first peaked at 4:02 a.m. EDT on April 2, the second peaked at 4:33 p.m. EDT on April 2, and the third peaked at 10:29 a.m. EDT on April 3. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured images of the three events. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel. Learn more: go.nasa.gov/2oQVFju Caption: NASA's Solar Dynamics Observatory captured this image of a solar flare peaking at 10:29 a.m. EDT on April 3, 2017, as seen in the bright flash near the sun’s upper right edge. The image shows a subset of extreme ultraviolet light that highlights the extremely hot material in flares and which is typically colorized in teal. Credits: NASA/SDO NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The DYNAMO Orbiter Project: High Resolution Mapping of Gravity/Magnetic Fields and In Situ Investigation of Mars Atmospheric Escape

NASA Technical Reports Server (NTRS)

Smrekar, S.; Chassefiere, E.; Forget, F.; Reme, H.; Mazelle, C.; Blelly, P. -L.; Acuna, M.; Connerney, J.; Purucker, M.; Lin, R.

2000-01-01

Dynamo is a small Mars orbiter planned to be launched in 2005 or 2007, in the frame of the NASA/CNES Mars exploration program. It is aimed at improving gravity and magnetic field resolution, in order to better understand the magnetic, geologic and thermal history of Mars, and at characterizing current atmospheric escape, which is still poorly constrained. These objectives are achieved by using a low periapsis orbit, similar to the one used by the Mars Global Surveyor spacecraft during its aerobraking phases. The proposed periapsis altitude for Dynamo of 120-130 km, coupled with the global distribution of periapses to be obtained during one Martian year of operation, through about 5000 low passes, will produce a magnetic/gravity field data set with approximately five times the spatial resolution of MGS. Low periapsis provides a unique opportunity to investigate the chemical and dynamical properties of the deep ionosphere, thermosphere, and the interaction between the atmosphere and the solar wind, therefore atmospheric escape, which may have played a crucial role in removing atmosphere, and water, from the planet. There is much room for debate on the importance of current atmosphere escape processes in the evolution of the Martian atmosphere, as early "exotic" processes including hydrodynamic escape and impact erosion are traditionally invoked to explain the apparent sparse inventory of present-day volatiles. Yet, the combination of low surface gravity and the absence of a substantial internally generated magnetic field have undeniable effects on what we observe today. In addition to the current losses in the forms of Jeans and photochemical escape of neutrals, there are solar wind interaction-related erosion mechanisms because the upper atmosphere is directly exposed to the solar wind. The solar wind related loss rates, while now comparable to those of a modest comet, nonetheless occur continuously, with the intriguing possibility of important cumulative and/or enhanced effects over the several billion years of the solar system's life. If the detailed history of the Martian internal field could be traced back, and the current escape processes could be understood well enough to model the expected stronger losses under early Sun conditions, one could go a long way toward constraining this part of the mysterious history of Mars' atmosphere.

Solar Terrestrial programs: A five year plan

NASA Technical Reports Server (NTRS)

Stern, D. P.

1978-01-01

Major projects to be initiated in the 1980-1985 period, designed to study the Sun, the heliosphere, Earth's magnetosphere, and the upper atmosphere involve the use of spacelab as well as free flying spacecraft. Current and recent investigations in these areas are reviewed and the guiding principles followed in planning future missions are examined. The implementation strategy, the planning process, and supporting research and technology are discussed.

Data Assimilation with the Extended Cmam: Nudging to Re-Analyses of the Lower Atmosphere

NASA Astrophysics Data System (ADS)

Fomichev, V. I.; Beagley, S. R.; Shepherd, M. G.; Semeniuk, K.; Mclandress, C. W.; Scinocca, J.; McConnell, J. C.

2012-12-01

The extended CMAM is currently being run in a forecast mode allowing the use of the model to simulate specific events. The current analysis period covers 1990-2010. The model is forced using ERA-Interim re-analyses via a nudging technique for the troposphere/stratosphere in combination with the GCM evolution in the lower atmosphere. Thus a transient forced model state is created in the lower atmosphere. The upper atmosphere is allowed to evolve in response to the observed conditions occurring in the lower atmosphere and in response to other transient forcing's such as SSTs, solar flux, and CO2 and CFC boundary changes. This methodology allows specific events and observations to be more successfully compared with the model. The model results compared to TOMS and ACE observations show a good agreement.

Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

NASA Astrophysics Data System (ADS)

Perez-Hoyos, Santiago; Sánchez-Lavega, A.

2009-09-01

We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

A combined solar and geomagnetic index for thermospheric climate

PubMed Central

Mlynczak, Martin G; Hunt, Linda A; Marshall, B Thomas; Russell, James M; Mertens, Christopher J; Thompson, R Earl; Gordley, Larry L

2015-01-01

Infrared radiation from nitric oxide (NO) at 5.3 µm is a primary mechanism by which the thermosphere cools to space. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics satellite has been measuring thermospheric cooling by NO for over 13 years. In this letter we show that the SABER time series of globally integrated infrared power (watts) radiated by NO can be replicated accurately by a multiple linear regression fit using the F10.7, Ap, and Dst indices. This allows reconstruction of the NO power time series back nearly 70 years with extant databases of these indices. The relative roles of solar ultraviolet and geomagnetic processes in determining the NO cooling are derived and shown to vary significantly over the solar cycle. The NO power is a fundamental integral constraint on the thermospheric climate, and the time series presented here can be used to test upper atmosphere models over seven different solar cycles. Key Points F10.7, Ap, and Dst replicate time series of radiative cooling by nitric oxide Quantified relative roles of solar irradiance, geomagnetism in radiative cooling Establish a new index and extend record of thermospheric cooling back 70 years PMID:26709319

A combined solar and geomagnetic index for thermospheric climate.

PubMed

Mlynczak, Martin G; Hunt, Linda A; Marshall, B Thomas; Russell, James M; Mertens, Christopher J; Thompson, R Earl; Gordley, Larry L

2015-05-28

Infrared radiation from nitric oxide (NO) at 5.3 µm is a primary mechanism by which the thermosphere cools to space. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics satellite has been measuring thermospheric cooling by NO for over 13 years. In this letter we show that the SABER time series of globally integrated infrared power (watts) radiated by NO can be replicated accurately by a multiple linear regression fit using the F 10.7 , Ap , and Dst indices. This allows reconstruction of the NO power time series back nearly 70 years with extant databases of these indices. The relative roles of solar ultraviolet and geomagnetic processes in determining the NO cooling are derived and shown to vary significantly over the solar cycle. The NO power is a fundamental integral constraint on the thermospheric climate, and the time series presented here can be used to test upper atmosphere models over seven different solar cycles. F 10.7 , Ap , and Dst replicate time series of radiative cooling by nitric oxide Quantified relative roles of solar irradiance, geomagnetism in radiative cooling Establish a new index and extend record of thermospheric cooling back 70 years.

Comparative Study on Hot Atom Coronae of Solar and Extrasolar Planets

NASA Astrophysics Data System (ADS)

Shematovich, Valery

Solar/stellar forcing on the upper atmospheres of the solar and extrasolar planets via both absorption of the XUV (soft X-rays and extreme ultraviolet) radiation and atmospheric sputtering results in the formation of an extended neutral corona populated by the suprathermal (hot) H, C, N, and O atoms (see, e.g., Johnson et al., 2008). The hot corona, in turn, is altered by an inflow of the solar wind/magnetospheric plasma and local pick-up ions onto the planetary exosphere. Such inflow results in the formation of the superthermal atoms (energetic neutral atoms - ENAs) due to the charge exchange with the high-energy precipitating ions and can affect the long-term evolution of the atmosphere due to the atmospheric escape. The origin, kinetics and transport of the suprathermal H, C, N, and O atoms in the transition regions (from thermosphere to exosphere) of the planetary atmospheres are discussed. Reactions of dissociative recombination of the ionospheric ions CO _{2} (+) , CO (+) , O _{2} (+) , and N _{2} (+) with thermal electrons are the main photochemical sources of hot atoms. The dissociation of atmospheric molecules by the solar/stellar XUV radiation and accompanying photoelectron fluxes and the induced exothermic photochemistry are also the important sources of the suprathermal atoms. Such kinetic systems with the non-thermal processes are usually investigated with the different (test particles, DSMC, and hybrid) versions of the kinetic Monte Carlo method. In our studies the kinetic energy distribution functions of suprathermal and superthermal atoms were calculated using the stochastic model of the hot planetary corona (Shematovich, 2004, 2010; Groeller et al., 2014), and the Monte Carlo model (Shematovich et al., 2011, 2013) of the high-energy proton and hydrogen atom precipitation into the atmosphere respectively. These functions allowed us to estimate the space distribution of suprathermals in the planetary transition regions. An application of these numerical models to study the atmospheric gas flow in the transition region from the collision-dominated thermosphere to collisionless exosphere, and the non-thermal escape will be discussed and illustrated with the simple 1D-models of the hot coronae of the solar and extrasolar planets. This work is supported by the RFBR project No. 14-02-00838a and by the Basic Research Program of the Presidium of the Russian Academy of Sciences (Program 22). begin{itemize} Johnson et al., Sp. Sci.Rev., 2008, v. 139, 355. Shematovich, Solar System Res., 2004, v.38, 28. Shematovich, Solar System Res., 2010, v.44, 96. Shematovich et al., J. Geophys. Res., 2011, v.116, A11320; 2013, v. 118, 1231. Groeller et al., Planet. Space Sci., 2014.

Time variations of solar UV irradiance as measured by the SOLSTICE (UARS) instrument

NASA Technical Reports Server (NTRS)

London, Julius; Rottman, Gary J.; Woods, Thomas N.; Wu, Fie

1993-01-01

An analysis is presented of solar ultraviolet irradiance measurements made by the SOLSTICE spectrometers on the Upper Atmosphere Research Satellite (UARS). Reported observations cover the wavelength interval 119-420 nm, and the analysis discussed here is for the time period 26 Nov 1991 to 31 Dec 1992, during which time solar activity decreased in intensity. At the time of peak activity, the average 27-day variation had a relative amplitude of about 8 percent at Ly-alpha, tailing off to about 0.6 percent at 260 nm. It is shown that over the spectral interval 119-260 nm, the relative 27-day harmonic was about a factor of two larger during the strongly disturbed as compared with the moderately disturbed period.

Organic chemistry on Titan

NASA Technical Reports Server (NTRS)

Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

1979-01-01

Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

Preliminary Results on Mars and the Siding Spring Meteor Shower from MAVEN's Imaging UV Spectrograph

NASA Astrophysics Data System (ADS)

Schneider, Nicholas

2015-04-01

The MAVEN mission to Mars is designed to study the upper atmosphere and its response to external drivers, searching for clues to the cause of long-term atmospheric loss. MAVEN carries the Imaging UV Spectrograph (IUVS) for remote sensing studies of the atmosphere through vertical scans from the limb through the corona, UV imaging of the planet and stellar occultations. Each observational mode has successfully observed the spectral features and spatial distributions as intended, confirming and expanding our understanding of the Mars upper atmosphere as observed by the Mariner spacecraft and Mars Express. Furthermore, IUVS witnessed the aftermath of an intense meteor shower on Mars caused by Comet Siding Spring. For a period of many hours, the planet's UV spectrum was dominated by emission from ionized magnesium deposited by meteor ablation in the upper atmosphere. Initial results from the originally-planned Mars observations include: • Significant persistent structures in the thermospheric day glow emissions, dependent primarily on solar zenith angle, along with significant variability on daily timescales; • Nitric oxide nightglow and low-level auroral emissions of substantially greater nightside extent than previously seen; • Confirmation of N2 emission in the VK band, as first reported by MEX/SPICAM; • The first vertical profiles of the D/H ratio in the atmosphere and their evolution with Mars season; • The most complete maps and vertical profiles of H, C and O in the Mars corona; • The first global snapshot of the middle atmosphere obtained by a day-long stellar occultation campaign; • Global ozone maps spanning several months of seasonal evolution. Other results from the missions's preliminary phases will be included.

KSC-2013-3478

NASA Image and Video Library

2013-08-27

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician cleans one of the cells of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/ Jim Grossmann

KSC-2013-3465

NASA Image and Video Library

2013-08-27

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians test a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/ Jim Grossmann

KSC-2013-3467

NASA Image and Video Library

2013-08-27

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician inspects a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/ Jim Grossmann

KSC-2013-3464

NASA Image and Video Library

2013-08-27

CAPE CANAVERAL, Fla. – Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, a technician tests a cell from one of the electricity-producing solar arrays for the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. MAVEN is being prepared for its scheduled launch in November from Cape Canaveral Air Force Station, Fla. atop a United Launch Alliance Atlas V rocket. Positioned in an orbit above the Red Planet, MAVEN will study the upper atmosphere of Mars in unprecedented detail. For more information, visit: http://www.nasa.gov/mission_pages/maven/main/index.html Photo credit: NASA/ Jim Grossmann

Phosphorus Chemistry in the Atmosphere of Jupiter: A Reassessment

NASA Astrophysics Data System (ADS)

Borunov, Sergei; Dorofeeva, Vera; Khodakovsky, Igor; Drossart, Pierre; Lellouch, Emmanuel; Encrenaz, Thérèse

1995-02-01

A new distribution of phosphorus compounds in the atmosphere of Jupiter is given, using revised values for the chemical constants. In contrast with previous works, it is shown that phosphine PH 3 remains the most abundant equilibrium gaseous compound even at the upper levels of Jupiter's troposphere. The observed PH 3 abundance is equal to the equilibrium value, at all temperatures above 535 K for solar P and O elemental abundances, and above 600 K for a reasonable range of P and O abundances. P 4O 6 does not take part in the phosphorus cycle on Jupiter.

In Situ Probe Science at Saturn

NASA Astrophysics Data System (ADS)

Atkinson, David H.; Lunine, Jonathan I.; Simon-Miller, Amy A.; Atreya, Sushil K.; Brinckerhoff, William B.; Colaprete, Anthony; Coustenis, Athena; Fletcher, Leigh N.; Guillot, Tristan; Lebreton, Jean-Pierre; Mahaffy, Paul; Mousis, Olivier; Orton, Glenn S.; Reh, Kim; Spilker, Linda J.; Spilker, Thomas R.; Webster, Chris R.

2014-05-01

A fundamental goal of solar system exploration is to understand the origin of the solar system, the initial stages, conditions, and processes by which the solar system formed, how the formation process was initiated, and the nature of the interstellar seed material from which the solar system was born. Key to understanding solar system formation and subsequent dynamical and chemical evolution is the origin and evolution of the giant planets and their atmospheres. Several theories have been put forward to explain the process of solar system formation, and the origin and evolution of the giant planets and their atmospheres. Each theory offers quantifiable predictions of the abundances of noble gases He, Ne, Ar, Kr, and Xe, and abundances of key isotopic ratios 4He/3He, D/H, 15N/14N, 18O/16O, and 13C/12C. Detection of certain disequilibrium species, diagnostic of deeper internal processes and dynamics of the atmosphere, would also help discriminate between competing theories. Many of the key atmospheric constituents needed to discriminate between alternative theories of giant planet formation and chemical evolution are either spectrally inactive or primarily located in the deeper atmosphere inaccessible to remote sensing from Earth, flyby, or orbiting spacecraft. Abundance measurements of these key constituents, including the two major molecular carriers of carbon, methane and carbon monoxide (neither of which condense in Saturn's atmosphere), sulfur which is expected to be well-mixed below the 4 to 5-bar ammonium hydrosulfide (NH4SH) cloud, and gradients of nitrogen below the NH4SH cloud and oxygen in the upper layers of the H2O and H2O-NH4 solution cloud, must be made in situ and can only be achieved by an entry probe descending through 10 bars. Measurements of the critical abundance profiles of these key constituents into the deeper well-mixed atmosphere must be complemented by measurements of the profiles of atmospheric structure and dynamics at high vertical resolution that also require in situ exploration. The atmospheres of the giant planets can also serve as laboratories to better understand the atmospheric chemistries, dynamics, processes, and climates on all planets in the solar system including Earth, and offer a context and provide a ground truth for exoplanets and exoplanetary systems. Additionally, Giant planets have long been thought to play a critical role in the development of potentially habitable planetary systems. In the context of giant planet science provided by the Galileo, Juno, and Cassini missions to Jupiter and Saturn, a small, relatively shallow Saturn probe capable of measuring abundances and isotopic ratios of key atmospheric constituents, and atmospheric structure including pressures, temperatures, dynamics, and cloud locations and properties not accessible by remote sensing can serve to test competing theories of solar system and giant planet origin, chemical, and dynamical evolution. Acknowledgements This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2013 California Institute of Technology. U.S. Government sponsorship acknowledged. O. Mousis acknowledges support from CNES.

UARS in-flight jitter study for EOS

NASA Technical Reports Server (NTRS)

Molnar, John; Garnek, Mike

1993-01-01

Response data collected from gyroscopes on board the Upper Atmosphere Research Satellite (UARS) provided a unique opportunity to analyze actual flight pointing jitter data. Flight modal frequencies and damping values are derived from the measured data using an Eigensystem Realization Algorithm (ERA). Flight frequencies at various solar array positions are compared to analytical predictions obtained with a Finite Element Model. The solar array modal frequencies change with position due to the modes acting about different spacecraft inertial axes. Higher order modes were difficult to identify due to the limited instrumentation. Future flight jitter studies on other spacecraft would be significantly aided by additional instrumentation. Spacecraft jitter due to continuous disturbance sources such as the 1.6 meter scanning microwave antenna, the solar array drive, and reaction wheels is presented. The solar array drive disturbance dominates the spacecraft response during normal operation.

SUMER: Solar Ultraviolet Measurements of Emitted Radiation

NASA Technical Reports Server (NTRS)

Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, M. C. E.; Lemaire, P.; Marsch, E.; Poland, A. I.

1988-01-01

The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established.

A comparison of photospheric electric current and ultraviolet and X-ray emission in a solar active region

NASA Astrophysics Data System (ADS)

Haisch, B. M.; Bruner, M. E.; Hagyard, M. J.; Bonnet, R. M.

1986-01-01

This paper presents an extensive set of coordinated observations of a solar active region, taking into account spectroheliograms obtained with the aid of the Solar Maximum Mission (SMM) Ultraviolet Spectrometer Polarimeter (UVSP) instrument, SMM soft X-ray polychromator (XRP) raster maps, and high spatial resolution ultraviolet images of the sun in Lyman-alpha and in the 1600 A continuum. These data span together the upper solar atmosphere from the temperature minimum to the corona. The data are compared to maps of the inferred photospheric electric current derived from the Marshall Space Flight Center (MSFC) vector magnetograph observations. Some empirical correlation is found between regions of inferred electric current density and the brightest features in the ultraviolet continuum and to a lesser extent those seen in Lyman-alpha within an active region.

Quantifying uncertainties of climate signals related to the 11-year solar cycle

NASA Astrophysics Data System (ADS)

Kruschke, T.; Kunze, M.; Matthes, K. B.; Langematz, U.; Wahl, S.

2017-12-01

Although state-of-the-art reconstructions based on proxies and (semi-)empirical models converge in terms of total solar irradiance, they still significantly differ in terms of spectral solar irradiance (SSI) with respect to the mean spectral distribution of energy input and temporal variability. This study aims at quantifying uncertainties for the Earth's climate related to the 11-year solar cycle by forcing two chemistry-climate models (CCMs) - CESM1(WACCM) and EMAC - with five different SSI reconstructions (NRLSSI1, NRLSSI2, SATIRE-T, SATIRE-S, CMIP6-SSI) and the reference spectrum RSSV1-ATLAS3, derived from observations. We conduct a unique set of timeslice experiments. External forcings and boundary conditions are fixed and identical for all experiments, except for the solar forcing. The set of analyzed simulations consists of one solar minimum simulation, employing RSSV1-ATLAS3 and five solar maximum experiments. The latter are a result of adding the amplitude of solar cycle 22 according to the five reconstructions to RSSV1-ATLAS3. Our results show that the climate response to the 11y solar cycle is generally robust across CCMs and SSI forcings. However, analyzing the variance of the solar maximum ensemble by means of ANOVA-statistics reveals additional information on the uncertainties of the mean climate signals. The annual mean response agrees very well between the two CCMs for most parts of the lower and middle atmosphere. Only the upper mesosphere is subject to significant differences related to the choice of the model. However, the different SSI forcings lead to significant differences in ozone concentrations, shortwave heating rates, and temperature throughout large parts of the mesosphere and upper stratosphere. Regarding the seasonal evolution of the climate signals, our findings for short wave heating rates, and temperature are similar to the annual means with respect to the relative importance of the choice of the model or the SSI forcing for the respective atmospheric layer. On the other hand, the predominantly dynamically driven signal in zonal wind is quite dependent on the choice of a CCM, mainly due to spatio-temporal shifts of similar responses. Within a given "model world" dynamical signals related to the different SSI forcings agree very well even under this monthly perspective.

Interannual Variations of MLS Carbon Monoxide Induced by Solar Cycle

NASA Technical Reports Server (NTRS)

Lee, Jae N.; Wu, Dong L.; Ruzmaikin, Alexander

2013-01-01

More than eight years (2004-2012) of carbon monoxide (CO) measurements from the Aura Microwave Limb Sounder (MLS) are analyzed. The mesospheric CO, largely produced by the carbon dioxide (CO2) photolysis in the lower thermosphere, is sensitive to the solar irradiance variability. The long-term variation of observed mesospheric MLS CO concentrations at high latitudes is likely driven by the solar-cycle modulated UV forcing. Despite of different CO abundances in the southern and northern hemispheric winter, the solar-cycle dependence appears to be similar. This solar signal is further carried down to the lower altitudes by the dynamical descent in the winter polar vortex. Aura MLS CO is compared with the Solar Radiation and Climate Experiment (SORCE) total solar irradiance (TSI) and also with the spectral irradiance in the far ultraviolet (FUV) region from the SORCE Solar-Stellar Irradiance Comparison Experiment (SOLSTICE). Significant positive correlation (up to 0.6) is found between CO and FUVTSI in a large part of the upper atmosphere. The distribution of this positive correlation in the mesosphere is consistent with the expectation of CO changes induced by the solar irradiance variations.

Venus atmosphere from Venus Express

NASA Astrophysics Data System (ADS)

Titov, Dmitri; Taylor, Fredric W.; Svedhem, Håkan; Titov, D.; Svedhem, H.; Taylor, F. W.; Bertaux, J.-L.; Drossart, P.; Haeusler, B.; Korablev, O. I.; Markiewicz, W. J.; Paetzold, M.; Piccioni, G.; Vandaele, A.-C.

Since April 2006 Venus Express has been performing a global survey of the remarkably dense, cloudy, and dynamic atmosphere of our near neighbour. A consistent picture of the climate on Venus is emerging on the basis of the new data on the global temperature structure, the com-position and its variations, the cloud morphology at various levels, the atmospheric dynamics and general circulation, and near-infrared emissions from trace species such as oxygen in the mesosphere. Vertical profiles of atmospheric temperature in the mesosphere and upper tropo-sphere show strong variability correlated with changes in the cloud top structure and many fine details indicating dynamical processes. Temperature sounding also shows that the main cloud deck at 50-60 km is convectively unstable over large portion of the planet, in agreement with the analysis of UV images. Imaging also reveals strong latitudinal variations and significant temporal changes in the global cloud top morphology, which will inevitably modulate the solar energy deposited in the atmosphere. The cloud top altitude varies from 72 km in the low and middle latitudes to 64 km in the polar region, marking vast polar depressions that form as a re-sult of the Hadley-type meridional circulation. Stellar and solar occultation measurements have revealed an extended upper haze of submicron particles and provided information on its optical properties. Solar occultation observations and deep atmosphere spectroscopy have quantified the distribution of the major trace gases H2O, SO2, CO, COS above and below the clouds, and so provided important input and validation for models of chemical cycles and dynamical trans-port. Cloud motion monitoring has characterised the mean state of the atmospheric circulation as well as its variability. Low and middle latitudes show an almost constant zonal wind speed of 100+/-20 m/s at the cloud tops and vertical wind shear of 2-3 m/s/km. Towards the pole, the wind speed drops quickly and the vertical shear vanishes. The meridional poleward wind ranges from 0 to about 15 m/s and there is some indication that it may change its direction at high latitudes. Comparison of the thermal wind field derived from temperature sounding to the cloud tracked winds confirms the approximate validity of cyclostrophic balance, at least in the latitude range from 30 S to 70 S. Maps of the non-LTE infrared emissions in the lines of O2, NO, CO2, OH originating near the mesopause at 95-105 km altitude show that the airglow peak intensity occurs close to the anti-solar point and its location depends on species. These observations promise significant improvement of thermospheric circulation models.

SMALL-SCALE STRUCTURING OF ELLERMAN BOMBS AT THE SOLAR LIMB

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

Nelson, C. J.; Doyle, J. G.; Scullion, E. M.

2015-01-01

Ellerman bombs (EBs) have been widely studied in recent years due to their dynamic, explosive nature and apparent links to the underlying photospheric magnetic field implying that they may be formed by magnetic reconnection in the photosphere. Despite a plethora of researches discussing the morphologies of EBs, there has been a limited investigation of how these events appear at the limb, specifically, whether they manifest as vertical extensions away from the disk. In this article, we make use of high-resolution, high-cadence observations of an Active Region at the solar limb, collected by the CRisp Imaging SpectroPolarimeter (CRISP) instrument, to identifymore » EBs and infer their physical properties. The upper atmosphere is also probed using the Solar Dynamic Observatory's Atmospheric Imaging Assembly (SDO/AIA). We analyze 22 EB events evident within these data, finding that 20 appear to follow a parabolic path away from the solar surface at an average speed of 9 km s{sup –1}, extending away from their source by 580 km, before retreating back at a similar speed. These results show strong evidence of vertical motions associated with EBs, possibly explaining the dynamical ''flaring'' (changing in area and intensity) observed in on-disk events. Two in-depth case studies are also presented that highlight the unique dynamical nature of EBs within the lower solar atmosphere. The viewing angle of these observations allows for a direct linkage between these EBs and other small-scale events in the Hα line wings, including a potential flux emergence scenario. The findings presented here suggest that EBs could have a wider-reaching influence on the solar atmosphere than previously thought, as we reveal a direct linkage between EBs and an emerging small-scale loop, and other near-by small-scale explosive events. However, as previous research found, these extensions do not appear to impact upon the Hα line core, and are not observed by the SDO/AIA EUV filters.« less

The SPICAV-SOIR instrument probing the atmosphere of Venus: an overview

NASA Astrophysics Data System (ADS)

Trompet, Loïc; Mahieux, Arnaud; Wilquet, Valérie; Robert, Séverine; Chamberlain, Sarah; Thomas, Ian; Carine Vandaele, Ann; Bertaux, Jean-Loup

2016-04-01

The Solar Occultation in the Infrared (SOIR) channel mounted on top of the SPICAV instrument of the ESA's Venus Express mission has observed the atmosphere of Venus during more than eight years. This IR spectrometer (2.2-4.3 μm) with a high spectral resolution (0.12 cm-1) combined an echelle grating with an acousto-optic tunable filter for order selection. SOIR performed more than 1500 solar occultation measurements leading to about two millions spectra. The Royal Belgian Institute for Space Aeronomy (BIRA-IASB) was in charge of SOIR's development and operations as well as its data pipeline. BIRA-IASB carried out several studies on the composition of Venus mesosphere and lower thermosphere: carbon dioxide, carbon monoxide, hydrogen halide (HF, HCl, DF, DCl), sulfur dioxide, water (H2O, HDO) as well as sulphuric acid aerosols in the upper haze of Venus. Density and temperature profiles of the upper atmosphere of Venus (60 km to 170 km) at the terminator have been retrieved from SOIR's spectra using different assumptions, wherein the hydrostatic equilibrium and the local thermodynamical equilibrium in the radiative transfer calculations. These results allow us to produce an Atmospheric model of Venus called Venus Atmosphere from SOIR measurements at the Terminator (VAST). Data obtained by SOIR will also contribute to update the Venus International Reference Atmosphere (VIRA). Recently, the treatment of the raw data to transmittance has been optimized, and a new dataset of spectra has been produced. All raw spectra (PSA level 2) as well as calibrated spectra (PSA level 3) have been delivered to ESA's Planetary Science Archive (PDSPSA). Consequently the re-analysis of all spectra has been undergone. We will briefly present the improvements implemented in the data pipeline. We will also show a compilation of results obtained by the instrument considering the complete mission duration.

He bulge revealed: He and CO2 diurnal and seasonal variations in the upper atmosphere of Mars as detected by MAVEN NGIMS

NASA Astrophysics Data System (ADS)

Elrod, M. K.; Bougher, S.; Bell, J.; Mahaffy, P. R.; Benna, M.; Stone, S.; Yelle, R.; Jakosky, B.

2017-02-01

Analysis of the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere Volatiles and EvolutioN (MAVEN) spacecraft closed source data from all orbits with good pointing revealed an enhanced Helium [He] density on the nightside orbits and a depressed He density on the dayside by about a factor of 10-20. He was also found to be larger in the polar regions than in the equatorial regions. The northern polar winter nightside He bulge was approximately twice that of the northern polar summer nightside bulge. The first 6 weeks of the MAVEN prime mission had periapsis at high latitudes on the nightside during northern winter, followed by the midlatitudes on the dayside moving to low latitudes on the nightside returning to the high latitudes during northern summer. In this study we examined the NGIMS data not only in the different latitudes but sorted by solar longitude (Ls) in order to separate the diurnal or local solar time (LST) effects from the seasonal effects. The Mars Global Ionosphere-Thermosphere Model (M-GITM) has predicted the formation of a He bulge in the upper atmosphere of Mars on the nightside early morning hours (Ls = 2-5 h) with more He collecting around the poles. Taking a slice at constant altitude across all orbits indicates corresponding variations in He and CO2 with respect to LST and Ls and a diurnal and seasonal dependence.

Martian Meteorology: Determination of Large Scale Weather Patterns from Surface Measurements

NASA Technical Reports Server (NTRS)

Murphy, James R.; Haberle, Robert M.; Bridger, Alison F. C.

1998-01-01

We employed numerical modelling of the martian atmosphere, and our expertise in understanding martian atmospheric processes, to better understand the coupling between lower and upper atmosphere processes. One practical application of this work has been our involvement with the ongoing atmospheric aerobraking which the Mars Global Surveyor (MGS) spacecraft is currently undergoing at Mars. Dr. Murphy is currently a member of the Mars Global Surveyor (MGS) Aerobraking Atmospheric Advisory Group (AAG). He was asked to participate in this activity based upon his knowledge of martian atmospheric dynamical processes. Aerobraking is a process whereby a spacecraft, in an elliptical orbit, passes through the upper layers of the atmosphere (in this instance Mars). This passage through the atmosphere 'drags'upon the spacecraft, gradually reducing its orbital velocity. This has the effect, over time, of converting the elliptical orbit to a circular orbit, which is the desired mapping orbit for MGS. Carrying out aerobraking eliminates the need for carrying large amounts of fuel on the spacecraft to execute an engine burn to achieve the desired orbit. Eliminating the mass of the fuel reduces the cost of launch. Damage to one of MGS's solar panels shortly after launch has resulted in a less aggressive extended in time aerobraking phase which will not end until March, 1999. Phase I extended from Sept. 1997 through March 1998. During this time period, Dr. Murphy participated almost daily in the AAG meetings, and beginning in December 1997 lead the meeting several times per week. The leader of each of the daily AAG meetings took the results of that meeting (current state of the atmosphere, identification of any time trends or spatial patterns in upper atmosphere densities, etc.) forward to the Aerobraking Planning Group (APG) meeting, at which time the decision was made to not change MGS orbit, to lower the orbit to reach higher densities (greater 'drag'), or raise the orbit to avoid experiencing excessive, possibly damaging densities.

Geocoronal hydrogen studies using Fabry Perot interferometers, part 2: Long-term observations

NASA Astrophysics Data System (ADS)

Nossal, S. M.; Mierkiewicz, E. J.; Roesler, F. L.; Reynolds, R. J.; Haffner, L. M.

2006-09-01

Long-term data sets are required to investigate sources of natural variability in the upper atmosphere. Understanding the influence of sources of natural variability such as the solar cycle is needed to characterize the thermosphere + exosphere, to understand coupling processes between atmospheric regions, and to isolate signatures of natural variability from those due to human-caused change. Multi-year comparisons of thermospheric + exospheric Balmer α emissions require cross-calibrated and well-understood instrumentation, a stable calibration source, reproducible observing conditions, separation of the terrestrial from the Galactic emission line, and consistent data analysis accounting for differences in viewing geometry. We discuss how we address these criteria in the acquisition and analysis of a mid-latitude geocoronal Balmer α column emission data set now spanning two solar cycles and taken mainly from Wisconsin and Kitt Peak, Arizona. We also discuss results and outstanding challenges for increasing the accuracy and use of these observations.

A flavor symmetry model for bilarge leptonic mixing and the lepton masses

NASA Astrophysics Data System (ADS)

Ohlsson, Tommy; Seidl, Gerhart

2002-11-01

We present a model for leptonic mixing and the lepton masses based on flavor symmetries and higher-dimensional mass operators. The model predicts bilarge leptonic mixing (i.e., the mixing angles θ12 and θ23 are large and the mixing angle θ13 is small) and an inverted hierarchical neutrino mass spectrum. Furthermore, it approximately yields the experimental hierarchical mass spectrum of the charged leptons. The obtained values for the leptonic mixing parameters and the neutrino mass squared differences are all in agreement with atmospheric neutrino data, the Mikheyev-Smirnov-Wolfenstein large mixing angle solution of the solar neutrino problem, and consistent with the upper bound on the reactor mixing angle. Thus, we have a large, but not close to maximal, solar mixing angle θ12, a nearly maximal atmospheric mixing angle θ23, and a small reactor mixing angle θ13. In addition, the model predicts θ 12≃ {π}/{4}-θ 13.

Using the transit of Venus to probe the upper planetary atmosphere.

PubMed

Reale, Fabio; Gambino, Angelo F; Micela, Giuseppina; Maggio, Antonio; Widemann, Thomas; Piccioni, Giuseppe

2015-06-23

During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80 km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70 km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena.

The Upper Atmosphere Research Satellite (UARS) mission

NASA Technical Reports Server (NTRS)

Reber, Carl A.; Trevathan, Charles E.; Mcneal, Robert J.; Luther, Michael R.

1993-01-01

The Upper Atmosphere Research Satellite (UARS) is a NASA program aimed at improving our knowledge of the physical and chemical processes controlling the stratosphere, mesosphere, and lower thermosphere, emphasizing those levels that are known to be particularly susceptible to change by human activities. The spacecraft was launched by the Space Shuttle Discovery on September 12, 1991 into a near-circular orbit at 585 km altitude and 57 deg inclination. Measurements include vertical profiles of temperature, many trace gases, and horizontal wind velocities, as well as solar energy inputs. Many of the limb-scanning instruments can measure to as high as 80 deg latitude, providing near-global coverage. The mission is supported by a large international correlative measurement program, yielding data both for validation of the UARS measurements and for complementary scientific studies. A dedicated data system provides rapid processing to geophysical quantities and makes these data available to UARS scientists.

Fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum

NASA Astrophysics Data System (ADS)

Michaelian, K.; Simeonov, A.

2015-02-01

The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short wavelength UVC and UVB dissipation. On Earth's surface, water and organic pigments in water facilitate the near UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UVC that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by; (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state life times, (3) quenching radiative de-excitation channels (e.g. fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of photosynthesis.

Distributions and Seasonal Variations of Tropospheric Ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) Solar Occultation Spectra

NASA Technical Reports Server (NTRS)

Herbin, H.; Hurtmans, D.; Clarisse, L.; Turquety, S.; Clerbaux, C.; Rinsland, Curtis P.; Boone, C.; Bernath, P. F.; Coheur, P.-F.

2009-01-01

This work reports the first measurements of ethene (C2H4) distributions in the upper troposphere. These are obtained by retrieving vertical profiles from 5 to 20 km from infrared solar occultation spectra recorded in 2005 and 2006 by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS). Background volume mixin^ ratios (vmrs) ranging from a few to about 50 pptv (10(exp -1) are measured at the different altitudes, while for certain occultations, vmrs as high as 200 pptv are observed. Zonal distributions and vertically resolved latitudinal distributions are derived for the two year period analyzed, highlighting spatial - including a North-South gradient - as well as seasonal variations. We show the latter to be more pronounced at the highest latitudes, presumably as a result of less active photochemistry during winter. The observation of C2H4 enhancements in remote Arctic regions at high latitudes is consistent with the occurrence of fast transport processes of gaseous pollution from the continents leading to Arctic haze. Citation: Herbin, H., D. Hurtmans, L. Clarisse, S. Turquety, C. Clerbaux, C. P. Rinsland, C. Boone, P. F. Bernath, and P.-F. Colieur (2009), Distributions and seasonal variations of tropospheric ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) solar occultation spectra,

On the plasma flow inside magnetic tornadoes on the Sun

NASA Astrophysics Data System (ADS)

Wedemeyer, Sven; Steiner, Oskar

2014-12-01

High-resolution observations with the Swedish 1-m Solar Telescope (SST) and the Solar Dynamics Observatory (SDO) reveal rotating magnetic field structures that extend from the solar surface into the chromosphere and the corona. These so-called magnetic tornadoes are primarily detected as rings or spirals of rotating plasma in the Ca II 854.2 nm line core (also known as chromospheric swirls). Detailed numerical simulations show that the observed chromospheric plasma motion is caused by the rotation of magnetic field structures, which again are driven by photospheric vortex flows at their footpoints. Under the right conditions, two vortex flow systems are stacked on top of each other. We refer to the lower vortex, which extends from the low photosphere into the convection zone, as intergranular vortex flow (IVF). Once a magnetic field structure is co-located with an IVF, the rotation is mediated into the upper atmospheric layers and an atmospheric vortex flow (AVF, or magnetic tornado) is generated. In contrast to the recent work by Shelyag et al. (2013, ApJ, 776, L4), we demonstrate that particle trajectories in a simulated magnetic tornado indeed follow spirals and argue that the properties of the trajectories decisively depend on the location in the atmosphere and the strength of the magnetic field.

Cassini observations of carbon-based anions in Titan's ionosphere

NASA Astrophysics Data System (ADS)

Desai, Ravindra; Lewis, Gethyn; Waite, J. Hunter; Kataria, Dhiren; Wellbrock, Anne; Jones, Geraint; Coates, Andrew

2016-07-01

Cassini observations of Titan's ionosphere revealed an atmosphere rich in positively and negatively charged ions and organic molecules. The detection of large quantities of negatively charged ions was particularly surprising and adds Titan to the growing list of locations where anion chemistry has been observed to play an important role. In this study we present updated analysis on these negatively charged ions through an enhanced understanding of the Cassini CAPS Electron Spectrometer (CAPS-ELS) instrument response. The ionisation of Titan's dominant atmospheric constituent, N2, by the HeII Solar line, results in an observable photoelectron population at 24.1eV which we use to correct for differential spacecraft charging. Correcting for further energy-angle signatures within this dataset, we use an updated fitting procedure to show how the ELS mass spectrum, previously grouped into broad mass ranges, can be resolved into specific peaks at multiples of carbon-based anion species up to over 100amu/q. These peaks are shown to be ubiquitous within Titan's upper atmosphere and reminiscent of carbon-based anions identified in dense molecular clouds beyond our Solar System. It is thus shown how the moon Titan in the Outer Solar System can be used as an analogue to study these even more remote and exotic astrophysical environments.

Origin and stability of exomoon atmospheres: implications for habitability.

PubMed

Lammer, Helmut; Schiefer, Sonja-Charlotte; Juvan, Ines; Odert, Petra; Erkaev, Nikolai V; Weber, Christof; Kislyakova, Kristina G; Güdel, Manuel; Kirchengast, Gottfried; Hanslmeier, Arnold

2014-09-01

We study the origin and escape of catastrophically outgassed volatiles (H2O, CO2) from exomoons with Earth-like densities and masses of 0.1, 0.5 and 1 M⊕ orbiting an extra-solar gas giant inside the habitable zone of a young active solar-like star. We apply a radiation absorption and hydrodynamic upper atmosphere model to the three studied exomoon cases. We model the escape of hydrogen and dragged dissociation products O and C during the activity saturation phase of the young host star. Because the soft X-ray and EUV radiation of the young host star may be up to ~100 times higher compared to today's solar value during the first 100 Myr after the system's origin, an exomoon with a mass < 0.25 M⊕ located in the HZ may not be able to keep an atmosphere because of its low gravity. Depending on the spectral type and XUV activity evolution of the host star, exomoons with masses between ~0.25 and 0.5 M⊕ may evolve to Mars-like habitats. More massive bodies with masses >0.5 M⊕, however, may evolve to habitats that are a mixture of Mars-like and Earth-analogue habitats, so that life may originate and evolve at the exomoon's surface.

What can we learn from simulating Stratospheric Sudden Warming periods with the Thermosphere-Ionosphere-Mesosphere-Electrodynamics GCM?

NASA Astrophysics Data System (ADS)

Maute, A. I.; Hagan, M. E.; Roble, R. G.; Richmond, A. D.; Yudin, V. A.; Liu, H.; Goncharenko, L. P.; Burns, A. G.; Maruyama, N.

2013-12-01

The ionosphere-thermosphere system is not only influenced from geospace but also by meteorological variability. Ionospheric observations of GPS TEC during the current solar cycle have shown that the meteorological variability is important during solar minimum, but also can have significant ionospheric effects during solar medium to maximum conditions. Numerical models can be used to help understand the mechanisms that couple the lower and upper atmosphere over the solar cycle. Numerical modelers invoke different methods to simulate realistic, specified events of meteorological variability, e.g. specify the lower boundary forcing, nudge the middle atmosphere, data assimilation. To study the vertical coupling, we first need to assess the numerical models and the various methods used to simulate realistic events with respect to the dynamics of the mesosphere-lower thermosphere (MLT) region, the electrodynamics, and the ionosphere. This study focuses on Stratospheric Sudden Warming (SSW) periods since these are associated with a strongly disturbed middle atmosphere which can have effects up to the ionosphere. We will use the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation model (TIME-GCM) to examine several recent SSW periods, e.g. 2009, 2012, and 2013. The SSW period in TIME-GCM will be specified in three different ways: 1. using reanalysis data to specify the lower boundary; 2. nudging the neutral atmosphere (temperature and winds) with the Whole Atmosphere Community Climate Model (WACCM)/Goddard Earth Observing System Model, Version 5 (GEOS-5) results; 3. nudging the background atmosphere (temperature and winds) with WACCM/GEOS5 results. The different forcing methods will be evaluated for the SSW periods with respect to the dynamics of the MLT region, the low latitude vertical drift changes, and the ionospheric effects for the different SSW periods. With the help of ionospheric data at different longitudinal sectors it will be possible to assess the simulations of the SSW periods and provide guidance for future studies.

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.

Models of Solar Wind Structures and Their Interaction with the Earth's Space Environment

NASA Astrophysics Data System (ADS)

Watermann, J.; Wintoft, P.; Sanahuja, B.; Saiz, E.; Poedts, S.; Palmroth, M.; Milillo, A.; Metallinou, F.-A.; Jacobs, C.; Ganushkina, N. Y.; Daglis, I. A.; Cid, C.; Cerrato, Y.; Balasis, G.; Aylward, A. D.; Aran, A.

2009-11-01

The discipline of “Space Weather” is built on the scientific foundation of solar-terrestrial physics but with a strong orientation toward applied research. Models describing the solar-terrestrial environment are therefore at the heart of this discipline, for both physical understanding of the processes involved and establishing predictive capabilities of the consequences of these processes. Depending on the requirements, purely physical models, semi-empirical or empirical models are considered to be the most appropriate. This review focuses on the interaction of solar wind disturbances with geospace. We cover interplanetary space, the Earth’s magnetosphere (with the exception of radiation belt physics), the ionosphere (with the exception of radio science), the neutral atmosphere and the ground (via electromagnetic induction fields). Space weather relevant state-of-the-art physical and semi-empirical models of the various regions are reviewed. They include models for interplanetary space, its quiet state and the evolution of recurrent and transient solar perturbations (corotating interaction regions, coronal mass ejections, their interplanetary remnants, and solar energetic particle fluxes). Models of coupled large-scale solar wind-magnetosphere-ionosphere processes (global magnetohydrodynamic descriptions) and of inner magnetosphere processes (ring current dynamics) are discussed. Achievements in modeling the coupling between magnetospheric processes and the neutral and ionized upper and middle atmospheres are described. Finally we mention efforts to compile comprehensive and flexible models from selections of existing modules applicable to particular regions and conditions in interplanetary space and geospace.

KSC-2013-2939

NASA Image and Video Library

2013-06-27

VANDENBERG AIR FORCE BASE, Calif. – The Orbital Sciences L-1011 aircraft takes off from Vandenberg Air Force Base in California at 9:30 p.m. EDT, headed over the Pacific Ocean to release the Pegasus XL rocket carrying NASA's Interface Region Imaging Spectrograph, or IRIS, solar observatory. Release of the rocket from under the wing of the aircraft is scheduled for 10:27 p.m. EDT. IRIS will open a new window of discovery using spectrometry and imaging to trace the flow of energy and plasma through the chromospheres and transition region into the sun’s corona. The spacecraft will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. This interface region, located between the sun's visible surface and its upper atmosphere, is where most of its ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida is managing the countdown and launch. For more information, visit http://www.nasa.gov/iris. Photo credit: NASA/Daniel Casper

KSC-2013-2910

NASA Image and Video Library

2013-06-25

VANDENBERG AIR FORCE BASE, Calif. – At Vandenberg Air Force Base in California, NASA hosted a prelaunch mission briefing on the Interface Region Imaging Spectrograph, or IRIS, solar observatory scheduled to launch on a Pegasus XL rocket. Participating in the news conference are George Diller, NASA Public Affairs, Dr. S. Pete Worden, director of NASA's Ames Research Center in Calif., Jeffrey Newmark, IRIS Program scientist at NASA Headquarters in Washington D.C., and Alan Title, IRIS principal investigator with Lockheed Martin. Scheduled for launch from Vandenberg on June 26, 2013, IRIS will open a new window of discovery by tracing the flow of energy and plasma through the chromospheres and transition region into the sun’s corona using spectrometry and imaging. The IRIS mission will observe how solar material moves, gathers energy and heats up as it travels through a largely unexplored region of the solar atmosphere. The interface region, located between the sun's visible surface and upper atmosphere, is where most of the sun's ultraviolet emission is generated. These emissions impact the near-Earth space environment and Earth's climate. For more information, visit http://www.nasa.gov/iris Photo credit: NASA/ Daniel Casper

History of Martian Atmosphere and Volatiles Derived From MAVEN Observations

NASA Astrophysics Data System (ADS)

Jakosky, B. M.

2017-12-01

The MAVEN spacecraft has been observing loss of volatiles from the Mars upper atmosphere to space for more than a full Mars year. By understanding the present-day loss rates and the processes that drive loss, we can extrapolate to past epochs and estimate the total amount of gas lost to space through time. The current total loss rate is more than 2 kg/s. With the increased loss rate in the past due to the greater solar EUV flux and solar-wind intensity early in history, we estimate that more than 0.5 bar of CO2 might have been lost to space. This plausibility argument is augmented by observations of the 38Ar/36Ar ratio today that provide a direct indication of the integrated loss through time; the measurements indicate that the majority of atmospheric gas has, in fact, been lost to space. Combined with the lack of carbonates on the surface that can be a reservoir for CO2 from an earlier, thick atmosphere, these results point to loss to space as having been the major process for driving the changes in the atmosphere. Loss to space appears to have been responsible for changing the Martian climate from an early, warm, wet environment to the cold, dry climate that we see today.

Atmos/Atlas 3 Infrared Profile Measurements of Trace Gases in The November 1994 Tropical and Subtropical Upper Troposphere

NASA Technical Reports Server (NTRS)

Rinsland, C. P.; Gunson, M. R.; Wang, P.-H.; Arduini, R. F.; Baum, B. A.; Minnis, P.; Minnis, P.; Goldman, A.; Abrams, M. C.; Zander, R.;

USSR and Eastern Europe Scientific Abstracts, Geophysics, Astronomy and Space, Number 394.

DTIC Science & Technology

1977-04-13

Abstracts of Scientific Articles 10 Temperature and Wind Variations in Upper Atmosphere 10 Prediction of Precipitation for Five Days 10 Short...34 Method in Sea Gravimetry ... 30 Frequency Characteristics of Filter in "Points of Intersection" Method 30 Page Gravitational Anomalies in the...Inclination of Axes of Rotation and Orbits of Planets 47 Effect of Solar Activity on Precipitation Regime 47 Gravitational Orientation Systems with Two

The Inner Heliosphere at Fifty

NASA Astrophysics Data System (ADS)

Luhmann, Janet G.

2013-09-01

Recent observations show that the Sun's magnetic field is flipping, marking one of the weakest sunspot cycle maxima in recent history. Many consequences have been observed and are under study, from a significant diminishing of the upper atmosphere's density [Solomon et al., 2010] to record low levels of geomagnetic activity [Richardson, 2013] to the large increase of local galactic cosmic ray fluxes starting in the preceding solar minimum [Mewaldt et al., 2010].

Organ Dose Assessment and Evaluation of Cancer Risk on Mars Surface

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee; Cucinotta, Francis A.

2011-01-01

Organ specific fluence spectra and doses for large solar particle events (SPE) and galactic cosmic rays (GCR) at various levels of solar activity are simulated on the surface of Mars using the HZETRN/QMSFRG computer code and the 2010 version of the Badhwar and O Neill GCR model. The NASA JSC propensity model of SPE fluence and occurrence is used to consider upper bounds on SPE fluence for increasing mission lengths. To account for the radiation transmission through the Mars atmosphere, a vertical distribution of Mars atmospheric thickness is calculated from the temperature and pressure data of Mars Global Surveyor. To describe the spherically distributed atmospheric distance on the Mars surface at each elevation, the directional cosine distribution is implemented. The resultant directional shielding by Mars atmosphere at each elevation is then coupled with vehicle and body shielding for organ dose estimates. Finally, cancer risks for astronauts exploring Mars can be assessed by applying the NASA Space Radiation Cancer Risk 2010 model with the resultant organ dose estimates. Variations of organ doses and cancer risk quantities on the surface of Mars, which are due to a 16-km elevation range between the Tharsis Montes and the Hellas impact basin, are visualized on the global topography of Mars measured by the Mars Orbiter Laser Altimeter. It is found that cancer incidence risks are about 2-fold higher than mortality risks with a disproportionate increase in skin and thyroid cancers for male and female astronauts and in breast cancer for female astronauts. The number of safe days, defined by the upper 95% percent confidence level to be below cancer limits, on Mars is analyzed for several Mars mission design scenarios.

A Web Application For Visualizing Empirical Models of the Space-Atmosphere Interface Region: AtModWeb

NASA Astrophysics Data System (ADS)

Knipp, D.; Kilcommons, L. M.; Damas, M. C.

2015-12-01

We have created a simple and user-friendly web application to visualize output from empirical atmospheric models that describe the lower atmosphere and the Space-Atmosphere Interface Region (SAIR). The Atmospheric Model Web Explorer (AtModWeb) is a lightweight, multi-user, Python-driven application which uses standard web technology (jQuery, HTML5, CSS3) to give an in-browser interface that can produce plots of modeled quantities such as temperature and individual species and total densities of neutral and ionized upper-atmosphere. Output may be displayed as: 1) a contour plot over a map projection, 2) a pseudo-color plot (heatmap) which allows visualization of a variable as a function of two spatial coordinates, or 3) a simple line plot of one spatial coordinate versus any number of desired model output variables. The application is designed around an abstraction of an empirical atmospheric model, essentially treating the model code as a black box, which makes it simple to add additional models without modifying the main body of the application. Currently implemented are the Naval Research Laboratory NRLMSISE00 model for neutral atmosphere and the International Reference Ionosphere (IRI). These models are relevant to the Low Earth Orbit environment and the SAIR. The interface is simple and usable, allowing users (students and experts) to specify time and location, and choose between historical (i.e. the values for the given date) or manual specification of whichever solar or geomagnetic activity drivers are required by the model. We present a number of use-case examples from research and education: 1) How does atmospheric density between the surface and 1000 km vary with time of day, season and solar cycle?; 2) How do ionospheric layers change with the solar cycle?; 3 How does the composition of the SAIR vary between day and night at a fixed altitude?

Space physics strategy-implementation study. Volume 1: Goals, objectives, strategy. A report to the Space Physics Subcommittee of the Space Science and Applications Advisory Committee

NASA Technical Reports Server (NTRS)

1991-01-01

Space physics is defined as the study of the heliosphere as one system; that is, of the Sun and solar wind, and their interactions with the upper atmospheres, ionospheres, and magnetospheres of the planets and comets, with energetic particles, and with the interstellar medium. This report contains a number of reports by different panels on the major topics in the space physics program including: (1) the cosmic and heliospheric physics program for the years 1995 to 2010; (2) ionosphere, thermosphere, and mesosphere studies; (3) magnetospheric physics; (4) solar physics; and (5) space physics theory.

Mercury's helium exosphere after Mariner 10's third encounter

NASA Technical Reports Server (NTRS)

Curtis, S. A.; Hartle, R. E.

1977-01-01

From Mariner 10 third encounter UV data, a value of .00045 was calculated as the fraction of the solar wind He++ flux intercepted and captured by Mercury's magnetosphere if the observed He atmosphere is maintained by the solar wind. If an internal source for He prevails, the corresponding upper bound for the global outgassing rate is estimated to be 4.5 x 10 to the 22nd power per sec. A surface temperature distribution was used which satisfies the heat equation over Mercury's entire surface using Mariner 10 determined mean surface thermal characteristics. The means stand off distance of Mercury's magnetopause averaged over Mercury's orbit was also used.

Wavelength Dependence of Solar Irradiance Enhancement During X-Class Flares and Its Influence on the Upper Atmosphere

NASA Technical Reports Server (NTRS)

Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Chamberlin, Phillip C.; Qian, Liying; Solomon, Stanley C.; Roble, Raymond G.; Xiao, Zuo

2013-01-01

The wavelength dependence of solar irradiance enhancement during flare events is one of the important factors in determining how the Thermosphere-Ionosphere (T-I) system responds to flares. To investigate the wavelength dependence of flare enhancement, the Flare Irradiance Spectral Model (FISM) was run for 61 X-class flares. The absolute and the percentage increases of solar irradiance at flare peaks, compared to pre-flare conditions, have clear wavelength dependences. The 0-14 nm irradiance increases much more (approx. 680% on average) than that in the 14-25 nm waveband (approx. 65% on average), except at 24 nm (approx. 220%). The average percentage increases for the 25-105 nm and 122-190 nm wavebands are approx. 120% and approx. 35%, respectively. The influence of 6 different wavebands (0-14 nm, 14-25 nm, 25-105 nm, 105- 120 nm, 121.56 nm, and 122-175 nm) on the thermosphere was examined for the October 28th, 2003 flare (X17-class) event by coupling FISM with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) under geomagnetically quiet conditions (Kp=1). While the enhancement in the 0-14 nm waveband caused the largest enhancement of the globally integrated solar heating, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for the 25-105 nm waveband (EUV), which accounts for about 33 K of the total 45 K temperature enhancement, and approx. 7.4% of the total approx. 11.5% neutral density enhancement. The effect of 122-175 nm flare radiation on the thermosphere is rather small. The study also illustrates that the high-altitude thermospheric response to the flare radiation at 0-175 nm is almost a linear combination of the responses to the individual wavebands. The upper thermospheric temperature and density enhancements peaked 3-5 h after the maximum flare radiation.

Wavelength Dependence of Solar Irradiance Enhancement During X-class Flares and Its Influence on the Upper Atmosphere

NASA Technical Reports Server (NTRS)

Huang, Yanshi; Richmond, A. D.

2013-01-01

The wavelength dependence of solar irradiance enhancement during flare events is one of the important factors in determining how the Thermosphere-Ionosphere (TI) system responds to flares. To investigate the wavelength dependence of flare enhancement, the Flare Irradiance Spectral Model (FISM) was run for 61X-class flares. The absolute and the percentage increases of solar irradiance at flare peaks, compared to pre-flare conditions, have clear wavelength dependences. The 0-4 nm irradiance increases much more ((is) approximately 680 on average) than that in the 14-25 nm waveband ((is) approximately 65 on average), except at 24 nm ( (is) approximately 220). The average percentage increases for the 25-105 nm and 122-190 nm wave bands are approximately 120 and approximately 35, respectively. The influence of 6 different wavebands (0-14 nm, 14-25 nm, 25-105 nm, 105-120 nm, 121.56 nm,and122-175 nm) on the thermosphere was examined for the October 28th, 2003 flare (X17-class) event by coupling FISM with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model(TIE-GCM) under geomagnetically quiet conditions (Kp=1). While the enhancement in the0-14nm waveband caused the largest enhancement of the globally integrated solar heating, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for the 25-105 nm waveband (EUV), which accounts for about 33 K of the total 45 K temperature enhancement, and approximately 7.4% of the total approximately 11.5% neutral density enhancement. The effect of 122-175 nm flare radiation on the thermosphere is rather small. The study also illustrates that the high-altitude thermospheric response to the flare radiation at 0-175 nm is almost a linear combination of the responses to the individual wavebands. The upper thermospheric temperature and density enhancements peaked 3-5 h after the maximum flare radiation.

Correlations Between Surficial Sulfur and a REE Crustal Assimilation Signature in Martian Shergottites

NASA Technical Reports Server (NTRS)

Jones, J. H.; Franz, H. B.

2015-01-01

Compared to terrestrial basalts, the Martian shergottite meteorites have an extraordinary range of Sr and Nd isotopic signatures. In addition, the S isotopic compositions of many shergottites show evidence of interaction with the Martian surface/ atmosphere through mass-independent isotopic fractionations (MIF, positive, non-zero delta(exp 33)S) that must have originated in the Martian atmosphere, yet ultimately were incorporated into igneous sulfides (AVS - acid-volatile sulfur). These positive delta(exp 33)S signatures are thought to be governed by solar UV photochemical processes. And to the extent that S is bound to Mars and not lost to space from the upper atmosphere, a positive delta(exp 33)S reservoir must be mass balanced by a complementary negative reservoir.

Electrodynamics on extrasolar giant planets

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

Koskinen, T. T.; Yelle, R. V.; Lavvas, P.

2014-11-20

Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. Recent models of ion drag on these planets, however, are based on thermal ionization only and do not include the upper atmosphere above the 1 mbar level. These models are also based on simplified equations of resistive magnetohydrodynamics that are not always valid in extrasolar planet atmospheres. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of Hmore » and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. Based on these results and assumed magnetic fields, we constrain the conductivity regimes on close-in EGPs and use a generalized Ohm's law to study the basic effects of electrodynamics in their atmospheres. We find that ion drag is important above the 10 mbar level where it can also significantly alter the energy balance through resistive heating. Due to frequent collisions of the electrons and ions with the neutral atmosphere, however, ion drag is largely negligible in the lower atmosphere below the 10 mbar level for a reasonable range of planetary magnetic moments. We find that the atmospheric conductivity decreases by several orders of magnitude in the night side of tidally locked planets, leading to a potentially interesting large-scale dichotomy in electrodynamics between the day and night sides. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially be used to constrain electrodynamics in the future.« less

The Pluto system after the New Horizons flyby

NASA Astrophysics Data System (ADS)

Olkin, Catherine B.; Ennico, Kimberly; Spencer, John

2017-10-01

In July 2015, NASA's New Horizons mission performed a flyby of Pluto, revealing details about the geology, surface composition and atmospheres of this world and its moons that are unobtainable from Earth. With a resolution as small as 80 metres per pixel, New Horizons' images identified a large number of surface features, including a large basin filled with glacial ices that appear to be undergoing convection. Maps of surface composition show latitudinal banding, with non-volatile material dominating the equatorial region and volatile ices at mid- and polar latitudes. This pattern is driven by the seasonal cycle of solar insolation. New Horizons' atmospheric investigation found the temperature of Pluto's upper atmosphere to be much cooler than previously modelled. Images of forward-scattered sunlight revealed numerous haze layers extending up to 200 km from the surface. These discoveries have transformed our understanding of icy worlds in the outer Solar System, demonstrating that even at great distances from the Sun, worlds can have active geologic processes. This Review addresses our current understanding of the Pluto system and places it in context with previous investigations. 

Depth of a strong jovian jet from a planetary-scale disturbance driven by storms.

PubMed

Sánchez-Lavega, A; Orton, G S; Hueso, R; García-Melendo, E; Pérez-Hoyos, S; Simon-Miller, A; Rojas, J F; Gómez, J M; Yanamandra-Fisher, P; Fletcher, L; Joels, J; Kemerer, J; Hora, J; Karkoschka, E; de Pater, I; Wong, M H; Marcus, P S; Pinilla-Alonso, N; Carvalho, F; Go, C; Parker, D; Salway, M; Valimberti, M; Wesley, A; Pujic, Z

2008-01-24

The atmospheres of the gas giant planets (Jupiter and Saturn) contain jets that dominate the circulation at visible levels. The power source for these jets (solar radiation, internal heat, or both) and their vertical structure below the upper cloud are major open questions in the atmospheric circulation and meteorology of giant planets. Several observations and in situ measurements found intense winds at a depth of 24 bar, and have been interpreted as supporting an internal heat source. This issue remains controversial, in part because of effects from the local meteorology. Here we report observations and modelling of two plumes in Jupiter's atmosphere that erupted at the same latitude as the strongest jet (23 degrees N). The plumes reached a height of 30 km above the surrounding clouds, moved faster than any other feature (169 m s(-1)), and left in their wake a turbulent planetary-scale disturbance containing red aerosols. On the basis of dynamical modelling, we conclude that the data are consistent only with a wind that extends well below the level where solar radiation is deposited.

The abundance and distribution of water vapor in the Jovian troposphere as inferred from Voyager IRIS observations

NASA Technical Reports Server (NTRS)

Carlson, Barbara E.; Lacis, Andrew A.; Rossow, William B.

1992-01-01

The Voyager IRIS spectra of the Jovian North Equatorial Belt (NEB) hot spots are reanalyzed using a radiative transfer model which includes the full effects of anisotropic multiple scattering by clouds. The atmospheric model includes the three thermochemically predicted cloud layers, NH3, NH4SH, and H2O. Spectrally dependent cloud extinction is modeled using Mie theory and the refractive indices of NH3 ice, NH4SH ice, water, and H2O ice. The upper tropospheric temperature profile, gas abundances, height-dependent parahydrogen profile, and vertical distribution of NH3 cloud opacity are retrieved from an analysis of the far-infrared (180-1200/cm) IRIS observations. With these properties constrained, the 5-micron (1800-2300/cm) observations are analyzed to determine the atmospheric and cloud structure of the deeper atmosphere (P of greater than 1.5 bars). The results show that the abundance of water is at least 1.5 times solar with 2 times solar (0.00276 mixing ratio relative to H2) providing the best-fit to the Voyager IRIS hot spot observations.

New Horizons Upper Limits on O{sub 2} in Pluto’s Present Day Atmosphere

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

Kammer, J. A.; Gladstone, G. R.; Stern, S. A.

The surprising discovery by the Rosetta spacecraft of molecular oxygen (O{sub 2}) in the coma of comet 67P/Churyumov–Gerasimenko challenged our understanding of the inventory of this volatile species on and inside bodies from the Kuiper Belt. That discovery motivated our search for oxygen in the atmosphere of Kuiper Belt planet Pluto, because O{sub 2} is volatile even at Pluto’s surface temperatures. During the New Horizons flyby of Pluto in 2015 July, the spacecraft probed the composition of Pluto’s atmosphere using a variety of observations, including an ultraviolet solar occultation observed by the Alice UV spectrograph. As described in these reports, absorptionmore » by molecular species in Pluto’s atmosphere yielded detections of N{sub 2}, as well as hydrocarbon species such as CH{sub 4}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}. Our work here further examines this data to search for UV absorption from molecular oxygen (O{sub 2}), which has a significant cross-section in the Alice spectrograph bandpass. We find no evidence for O{sub 2} absorption and place an upper limit on the total amount of O{sub 2} in Pluto’s atmosphere as a function of tangent height up to 700 km. In most of the atmosphere, this upper limit in line-of-sight abundance units is ∼3 × 10{sup 15} cm{sup −2}, which, depending on tangent height, corresponds to a mixing ratio of 10{sup −6} to 10{sup −4}, far lower than in comet 67P/CG.« less

Absorption of solar energy heats up our planet's surface and the atmosphere and makes life for us po

NASA Technical Reports Server (NTRS)

2002-01-01

Credit: Image courtesy Barbara Summey, NASA Goddard Visualization Analysis Lab, based upon data processed by Takmeng Wong, CERES Science Team, NASA Langley Research Center Satellite: Terra Sensor: CERES Image Date: 09-30-2001 VE Record ID: 11546 Description: Absorption of solar energy heats up our planet's surface and the atmosphere and makes life for us possible. But the energy cannot stay bound up in the Earth's environment forever. If it did then the Earth would be as hot as the Sun. Instead, as the surface and the atmosphere warm, they emit thermal longwave radiation, some of which escapes into space and allows the Earth to cool. This false-color image of the Earth was produced on September 30, 2001, by the Clouds and the Earth's Radiant Energy System (CERES) instrument flying aboard NASA's Terra spacecraft. The image shows where more or less heat, in the form of longwave radiation, is emanating from the top of Earth's atmosphere. As one can see in the image, the thermal radiation leaving the oceans is fairly uniform. The blue swaths across the central Pacific represent thick clouds, the tops of which are so high they are among the coldest places on Earth. In the American Southwest, which can be seen in the upper righthand corner of the globe, there is often little cloud cover to block outgoing radiation and relatively little water to absorb solar energy. Consequently, the amount of outgoing radiation in the American Southwest exceeds that of the oceans. Also, that region was experiencing an extreme heatwave when these data were acquired. Recently, NASA researchers discovered that incoming solar radiation and outgoing thermal radiation increased in the tropics from the 1980s to the 1990s. (Click to read the press release .) They believe that the reason for the unexpected increase has to do with an apparent change in circulation patterns around the globe, which effectively reduced the amount of water vapor and cloud cover in the upper reaches of the atmosphere. Without the clouds, more sunlight was allowed to enter the tropical zones and more thermal energy was allowed to leave. The findings may have big implications for climate change and future global warming. 'This suggests that the tropical heat engine increased its speed,' observes Dr. Bruce Wielicki, of NASA Langley Research Center. 'It's as if the heat engine in the tropics has become less efficient, using more fuel in the 1990s than in the 1980s.'

Fiber-Optic Coupled Lidar Receiver System to Measure Stratospheric Ozone

NASA Technical Reports Server (NTRS)

Harper, David Brent; Elsayed-Ali, Hani

1998-01-01

The measurement of ozone in the atmosphere has become increasingly important over the past two decades. Significant increases of ozone concentrations in the lower atmosphere, or troposphere, and decreases in the upper atmosphere, or stratosphere, have been attributed to man-made causes. High ozone concentrations in the troposphere pose a health hazard to plants and animals and can add to global warming. On the other hand, ozone in the stratosphere serves as a protective barrier against strong ultraviolet (UV) radiation from the sun. Man-made CFC's (chlorofluorocarbons) act as a catalyst with a free oxygen atom and an ozone molecule to produce two oxygen molecules therefore depleting the protective layer of ozone in the stratosphere. The beneficial and harmful effects of ozone require the study of ozone creation and destruction processes in the atmosphere. Therefore, to provide an accurate model of these processes, an ozone lidar system must be able to be used frequently with as large a measurement range as possible. Various methods can be used to measure atmospheric ozone concentrations. These include different airborne and balloon measurements, solar occulation satellite techniques, and the use of lasers in lidar (high detection and ranging,) systems to probe the atmosphere. Typical devices such as weather balloons can only measure within the direct vicinity of the instrument and are therefore used infrequently. Satellites use solar occulation techniques that yield low horizontal and vertical resolution column densities of ozone.

The Hinode(Solar-B)Mission: An Overview

NASA Technical Reports Server (NTRS)

Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone, Y.; Tachikawa, S.; Minesugi, K.; Ohnishi, A.; Yamada, T.; Tsuneta, S.;

Digital solar edge tracker for the Halogen Occultation Experiment

NASA Technical Reports Server (NTRS)

Mauldin, L. E., III; Moore, A. S.; Stump, C. W.; Mayo, L. S.

1987-01-01

The optical and electronic design of the Halogen Occultation Experiment (Haloe) elevation sun sensor is described. The Haloe instrument is a gas-correlation radiometer now being developed at NASA Langley for the Upper Atmosphere Research Satellite. The system uses a Galilean telescope to form a solar image on a linear silicon photodiode array. The array is a self-scanned monolithic CCD. The addresses of both solar edges imaged on the array are used by the control/pointing system to scan the Haloe science instantaneous field of view (IFOV) across the vertical solar diameter during instrument calibration and then to maintain the science IFOV 4 arcmin below the top edge during the science data occultation event. Vertical resolution of 16 arcsec and a radiometric dynamic range of 100 are achieved at the 700-nm operating wavelength. The design provides for loss of individual photodiode elements without loss of angular tracking capability.

Comparison of photospheric electric current and ultraviolet and x-ray emission in a solar active region

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

Haisch, B.M.; Bruner, M.E.; Hagyard, M.J.

This paper presents an extensive set of coordinated observations of a solar active region, taking into account spectroheliograms obtained with the aid of the Solar Maximum Mission (SMM) Ultraviolet Spectrometer Polarimeter (UVSP) instrument, SMM soft x-ray polychromator (XRP) raster maps, and high spatial resolution ultraviolet images of the sun in Lyman-alpha and in the 1600 A continuum. These data span together the upper solar atmosphere from the temperature minimum to the corona. The data are compared to maps of the inferred photospheric electric current derived from the Marshall Space Flight Center (MSFC) vector magnetograph observations. Some empirical correlation is foundmore » between regions of inferred electric current density and the brightest features in the ultraviolet continuum and to a lesser extent those seen in Lyman-alpha within an active region. 29 references.« less

Investigation of the middle atmosphere of Venus as a key to understand its dynamics

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Khatountsev, I. V.; Ignatiev, N. I.; Moroz, V. I.; Formisano, V.; Bellucci, G.

2001-11-01

Middle atmosphere of Venus (50 - 100km) is a very important part of the atmosphere. More than 70 % of the absorbed solar energy deposits there, providing an important source of energy to support thermal structure and dynamics. We investigate the thermal tides distribution, which is possibly responsible for the support of the superrotation. Temperature and aerosol vertical profiles were retrieved in a self consistent way from Venera-15 IR spectrometry data with vertical resolution of several kilometers. The temperature variation at the isobaric levels vs. solar longitude was presented as a superposition of the cosines with periods of 1, 1/2, 1/3 and 1/4 Venusian days with amplitude and phase depending on latitude and altitude. In particular, in the upper clouds, where most of the solar energy absorbs, all four tidal components have significant amplitudes. For the midlatitude jet the solar related periods were also found with maximal amplitude of 1/2 days period. It was also discovered that the jet changes its position in such a way that the laws of the conservation of momentum and flux are satisfied. The Fourier spectrometer on Venera-15 may be considered as a precursor of the instrument of this kind for the future missions. A functioning of the Planetary Fourier Spectrometer, with spectral range 1-50 mkm, proposed for Venus Express mission together with UV (0.2-0.5 mm) mapping spectrometer, will be enable to get answers to the fundamental questions of the middle atmosphere: clouds formation, nature of the ``unknown" UV-absorber and the mechanism of support of the superrotation. This work was supported by the grant RFFI - 02-01-17841.

Alice Solar Occultation

NASA Image and Video Library

2015-07-17

This figure shows how the Alice instrument count rate changed over time during the sunset and sunrise observations. The count rate is largest when the line of sight to the sun is outside of the atmosphere at the start and end times. Molecular nitrogen (N2) starts absorbing sunlight in the upper reaches of Pluto's atmosphere, decreasing as the spacecraft approaches the planet's shadow. As the occultation progresses, atmospheric methane and hydrocarbons can also absorb the sunlight and further decrease the count rate. When the spacecraft is totally in Pluto's shadow the count rate goes to zero. As the spacecraft emerges from Pluto's shadow into sunrise, the process is reversed. By plotting the observed count rate in the reverse time direction, it is seen that the atmospheres on opposite sides of Pluto are nearly identical. http://photojournal.jpl.nasa.gov/catalog/PIA19716

Investigations of the Mars Upper Atmosphere with ExoMars Trace Gas Orbiter

NASA Astrophysics Data System (ADS)

López-Valverde, Miguel A.; Gerard, Jean-Claude; González-Galindo, Francisco; Vandaele, Ann-Carine; Thomas, Ian; Korablev, Oleg; Ignatiev, Nikolai; Fedorova, Anna; Montmessin, Franck; Määttänen, Anni; Guilbon, Sabrina; Lefevre, Franck; Patel, Manish R.; Jiménez-Monferrer, Sergio; García-Comas, Maya; Cardesin, Alejandro; Wilson, Colin F.; Clancy, R. T.; Kleinböhl, Armin; McCleese, Daniel J.; Kass, David M.; Schneider, Nick M.; Chaffin, Michael S.; López-Moreno, José Juan; Rodríguez, Julio

2018-02-01

The Martian mesosphere and thermosphere, the region above about 60 km, is not the primary target of the ExoMars 2016 mission but its Trace Gas Orbiter (TGO) can explore it and address many interesting issues, either in-situ during the aerobraking period or remotely during the regular mission. In the aerobraking phase TGO peeks into thermospheric densities and temperatures, in a broad range of latitudes and during a long continuous period. TGO carries two instruments designed for the detection of trace species, NOMAD and ACS, which will use the solar occultation technique. Their regular sounding at the terminator up to very high altitudes in many different molecular bands will represent the first time that an extensive and precise dataset of densities and hopefully temperatures are obtained at those altitudes and local times on Mars. But there are additional capabilities in TGO for studying the upper atmosphere of Mars, and we review them briefly. Our simulations suggest that airglow emissions from the UV to the IR might be observed outside the terminator. If eventually confirmed from orbit, they would supply new information about atmospheric dynamics and variability. However, their optimal exploitation requires a special spacecraft pointing, currently not considered in the regular operations but feasible in our opinion. We discuss the synergy between the TGO instruments, specially the wide spectral range achieved by combining them. We also encourage coordinated operations with other Mars-observing missions capable of supplying simultaneous measurements of its upper atmosphere.

Photochemical Modeling of CH3 Abundances in the Outer Solar System

NASA Technical Reports Server (NTRS)

Lee, Anthony Y. T.; Yung, Yuk L.; Moses, Julianne

2000-01-01

Recent measurements of methyl radicals (CH3) in the upper atmospheres of Saturn and Neptune by the Infrared Space Observatory (ISO) provide new constraints to photochemical models of hydrocarbon chemistry in the outer solar system. The derived column abundances of CH3 on Saturn above 10 mbar and Neptune above the 0.2 mbar pressure level are (2.5 - 6.0) x 10(exp 13) / sq cm and (0.7 - 2.8) x 10(exp 13) / sq cm, respectively. We use the updated Caltech/Jet Propulsion Laboratory photochemical model, which incorporates hydrocarbon photochemistry, vertical molecular and bulk atmospheric eddy diffusion, and realistic radiative transfer modeling, to study the CH3 abundances in the upper atmosphere of the giant planets and Titan. We identify the key reactions that control the concentrations of CH3 in the model, such as the three-body recombination reaction, CH3 + CH3 + M yields C2H6 + M. We evaluate and extrapolate the three-body rate constant of this reaction to the low-temperature limit (1.8 x 10(exp -16) T(sup -3.75) e(sup -300/T), T < 300 K) and compare methyl radical abundances in five atmospheres: Jupiter, Saturn, Uranus, Neptune, and Titan. The sensitivity of our models to the rate coefficients for the reactions H + CH3 + M yields CH4 + M, H + C2H3 yields C2H2 + H2, (sup 1)CH2 + H2 yields CH3 + H, and H + C2H5 yields 2CH3, the branching ratios of CH4 photolysis, vertical mixing in the five atmospheres, and Lyman alpha photon enhancement at the orbit of Neptune have all been tested. The results of our model CH3 abundances for both Saturn (5.1 x 10(exp 13) / sq cm) and Neptune (2.2 x 10(exp 13) / sq cm) show good agreement with ISO Short Wavelength Spectrometer measurements. Using the same chemical reaction set, our calculations also successfully generate vertical profiles of stable hydrocarbons consistent with Voyager and ground-based measurements in these outer solar system atmospheres. Predictions of CH3 column concentrations (for p <= 0.2 mbar) in the atmospheres of Jupiter (3.3 x 10(exp 13) /sq cm), Uranus (2.5 x 10(exp 12) / sq cm), and Titan (1.9 x 10(exp 15) / sq cm) may be checked by future observations.

Atmospheric consequences of cosmic ray variability in the extragalactic shock model: 2. Revised ionization levels and their consequences

NASA Astrophysics Data System (ADS)

Melott, Adrian L.; Atri, Dimitra; Thomas, Brian C.; Medvedev, Mikhail V.; Wilson, Graham W.; Murray, Michael J.

2010-08-01

It has been suggested that galactic shock asymmetry induced by our galaxy's infall toward the Virgo Cluster may be a source of periodicity in cosmic ray exposure as the solar system oscillates perpendicular to the galactic plane, thereby, inducing an observed terrestrial periodicity in biodiversity. There are a number of plausible mechanisms by which cosmic rays might affect terrestrial biodiversity. Here we investigate one of these mechanisms, the consequent ionization and dissociation in the atmosphere, resulting in changes in atmospheric chemistry that culminate in the depletion of ozone and a resulting increase in the dangerous solar UVB flux on the ground. We use a heuristic model of the cosmic ray intensity enhancement originally suggested by Medvedev and Melott (2007) to compute steady state atmospheric effects. This paper is a reexamination of an issue we have studied before with a simplified approximation for the distribution of incidence angles. The new results are based on an improved ionization background computation averaged over a massive ensemble (about 7 × 105) shower simulations at various energies and incidence angles. We adopt a range with a minimal model and a fit to full exposure to the postulated extragalactic background. The atmospheric effects are greater than they were with our earlier, simplified ionization model. At the lower end of the intensity range, we find that the effects are too small to be of serious consequence. At the upper end of this range, ˜6% global average loss of ozone column density exceeds that currently experienced due to anthropogenic effects such as accumulated chlorofluorocarbons. We discuss some of the possible effects. The intensity of the atmospheric effects is less than those of a nearby supernova or galactic γ ray burst, but the duration of the effects would be about 106 times longer. Present UVB enhancement from current ozone depletion ˜3% is a documented stress on the biosphere, but a depletion of the magnitude found at the upper end of our range would approximately double the global average UVB flux. We conclude that for estimates at the upper end of the reasonable range of the cosmic ray variability over geologic time, the mechanism of atmospheric ozone depletion may provide a major biological stress, which could easily bring about major loss of biodiversity. It is possible that future high-energy astrophysical observations will resolve the question of whether such depletion is likely.

Detection of CO and HCN in Pluto's atmosphere with ALMA

NASA Astrophysics Data System (ADS)

Lellouch, E.; Gurwell, M.; Butler, B.; Fouchet, T.; Lavvas, P.; Strobel, D. F.; Sicardy, B.; Moullet, A.; Moreno, R.; Bockelée-Morvan, D.; Biver, N.; Young, L.; Lis, D.; Stansberry, J.; Stern, A.; Weaver, H.; Young, E.; Zhu, X.; Boissier, J.

2017-04-01

Observations of the Pluto-Charon system, acquired with the ALMA interferometer on June 12-13, 2015, have led to the detection of the CO(3-2) and HCN(4-3) rotational transitions from Pluto (including the hyperfine structure of HCN), providing a strong confirmation of the presence of CO, and the first observation of HCN in Pluto's atmosphere. The CO and HCN lines probe Pluto's atmosphere up to ∼450 km and ∼900 km altitude, respectively, with a large contribution due to limb emission. The CO detection yields (i) a much improved determination of the CO mole fraction, as 515 ± 40 ppm for a 12 μbar surface pressure (ii) strong constraints on Pluto's mean atmospheric dayside temperature profile over ∼50-400 km, with clear evidence for a well-marked temperature decrease (i.e., mesosphere) above the 30-50 km stratopause and a best-determined temperature of 70 ± 2 K at 300 km, somewhat lower than previously estimated from stellar occultations (81 ± 6 K), and in agreement with recent inferences from New Horizons / Alice solar occultation data. The HCN line shape implies a high abundance of this species in the upper atmosphere, with a mole fraction >1.5 × 10-5 above 450 km and a value of 4 × 10-5 near 800 km. Assuming HCN at saturation, this would require a warm (>92 K) upper atmosphere layer; while this is not ruled out by the CO emission, it is inconsistent with the Alice-measured CH4 and N2 line-of-sight column densities. Taken together, the large HCN abundance and the cold upper atmosphere imply supersaturation of HCN to a degree (7-8 orders of magnitude) hitherto unseen in planetary atmospheres, probably due to a lack of condensation nuclei above the haze region and the slow kinetics of condensation at the low pressure and temperature conditions of Pluto's upper atmosphere. HCN is also present in the bottom ∼100 km of the atmosphere, with a 10-8-10-7 mole fraction; this implies either HCN saturation or undersaturation there, depending on the precise stratopause temperature. The HCN column is (1.6 ± 0.4)× 1014 cm-2 , suggesting a surface-referred vertically-integrated net production rate of ∼2 × 107 cm-2 s-1. Although HCN rotational line cooling affects Pluto's atmosphere heat budget, the amounts determined in this study are insufficient to explain the well-marked mesosphere and upper atmosphere's ∼70 K temperature, which if controlled by HCN cooling would require HCN mole fractions of (3-7) ×10-4 over 400-800 km. We finally report an upper limit on the HC3N column density (<2 × 1013 cm-2) and on the HC15N / HC14N ratio (<1/125).

Dynamics of the Upper Atmosphere X-ray Emission during the 23rd Solar Cycle

NASA Astrophysics Data System (ADS)

Pugacheva, Galina; Gusev, Anatoly; Martin, Inácio M.; Spjeldvik, Walther

Long-term observations with the RPS-1instrument on the CORONAS-F satellite (July 2001 to December 2005) permitted the evaluation of the low energy 3.0-31.5 keV X-ray emission flux radiated by the upper nocturnal atmosphere. This emission mostly results from the bremsstrahlung radiation from magnetospheric electrons. The entire nocturnal atmosphere emits energy in the range of 3 to 5 keV, especially in the southern hemisphere, over the Pacific and Indian ocean areas. In the northern hemisphere, the brightest emission from the atmo-sphere is observed at high latitudes in the region of Earth's radiation belt (ERB). In lower northern latitudes, the X-ray emission intensity is rather weak especially during the summer, and on 5-8 keV maps there are regions where there are no discernible emissions. At energies higher than 8 keV, only areas over the South-Atlantic magnetic anomaly and ERB at high latitudes are distinctly observed. This emission is produced by X-rays arising from interactions of ERB particles, descending to the altitude of 500 km in their bounce motion with the am-bient atmospheric matter, and by direct ERB particles passing through the lateral walls and entrance window of the detector (electrons with energies higher than 100 keV and protons with energies higher than 3 MeV). In order to determine the source mechanisms of soft X-rays in the energy range 3 to 8 keV from regions in the ERB, we studied the relationship between the seasonal variation of the X-ray atmospheric radiation and phases of the solar activity cycle. The global monthly, six-monthly, and yearly-averaged X-ray flux distributions were statistically determined for the five-year duration of the CORONAS-F mission. From these distributions, it is possible to infer about the influence of the phase of the solar activity and seasonal effects on the fluxes with energy in the range of 3 to 8 keV. Analysis of these data revealed important regularities in the behavior of this emission. We noted that the emission decreased about 10 times from 2001 to 2005, i.e. from maximum to almost minimum of the solar activity cycle 23 when mean annual values of sunspot number decreased from 110.6 to 28.9. Some compact terrestrial sources of unknown origin located outside of ERB zones were detected. Also, X-rays flux distributions out of ERB were obtained during five strong geomagnetic storms that oc-curred during the CORONAS-F mission on November 6 and 24, 2001; October 28 to November 4, 2003; November 20, 2004; and May15, 2005. (To the memory of V.M. Pankov and V.L. Prokhin, colleagues and coworkers in the Coronas-F mission.)

Infrared radiation and inversion population of CO2 laser levels in Venusian and Martian atmospheres

NASA Technical Reports Server (NTRS)

Gordiyets, B. F.; Panchenko, V. Y.

1983-01-01

Formation mechanisms of nonequilibrium 10 micron CO2 molecule radiation and the possible existence of a natural laser effect in the upper atmospheres of Venus and Mars are theoretically studied. An analysis is made of the excitation process of CO2 molecule vibrational-band levels (with natural isotropic content) induced by direct solar radiation in bands 10.6, 9.4, 4.3, 2.7 and 2.0 microns. The model of partial vibrational-band temperatures was used in the case. The problem of IR radiation transfer in vibrational-rotational bands was solved in the radiation escape approximation.

Climate and smoke - An appraisal of nuclear winter

NASA Technical Reports Server (NTRS)

Turco, R. P.; Toon, O. B.; Pollack, J. B.; Ackerman, T. P.; Sagan, C.

1990-01-01

A reevaluation is presented of the 'nuclear winter' scenario of Turco et al. (1983). New pertinent data have emerged from laboratory studies, field experiments, and numerical models on the smoke-plume, mesoscale, and global scales. A full-scale nuclear exchange's probable soot injections lead, in three-dimensional climate simulations, to midsummer land temperature decreases averaging 10-20 C in northern midlatitudes, with local cooling of as much as 35 C. Anomalous circulation patterns due to solar heating of the soot could stabilize the upper atmosphere against overturning, thereby prolonging the soot's residence time in the atmosphere. Monsoon disruptions and severe ozone layer depletion are also foreseen.

Diurnal observations of HCl altitude variation in the 70-100 km mesosphere of Venus

NASA Astrophysics Data System (ADS)

Sandor, Brad J.; Todd Clancy, R.

2017-07-01

First submm spectroscopic observations of the 625.9 GHz H35Cl absorption lines of the Venus dayside atmosphere were obtained with the James Clerk Maxwell Telescope (JCMT) on March 2, 2013. These data, which support retrieval of HCl altitude distributions in the Venus mesosphere (70-100 km), are presented here and compared with previously reported JCMT observations of Venus nightside HCl (Sandor et al., 2012). The measured dayside profile agrees with that of the nightside, indicating no diurnal variation is present. More specifically, the nightside spectra revealed a secular decrease of upper mesospheric HCl between observations one month apart, at fixed latitude and local time. The dayside profile reported here presents upper mesospheric abundances that are bracketed by the two previously measured nightside profiles, indicating that if diurnal variation is present, it must be weaker than the secular variations occurring at fixed local time. The previous study, which measured nightside HCl abundances above 85 km to be much smaller than predicted from photochemical modeling, suggested a dynamical explanation for the disagreement wherein nightside downwelling associated with the SubSolar to AntiSolar (SSAS) atmospheric circulation might suppress upper mesospheric abundances predicted purely from photochemistry. However a straightforward prediction from the proposed mechanism is that HCl abundance on the dayside, where the SSAS drives upward rather than downward transport should at least agree with, and perhaps exceed that of the photochemical model. The finding that dayside HCl abundance agrees with that of the nightside, hence also is much smaller than that of the model shows the SSAS hypothesis to be incorrect.

Upper Atmosphere Research Report Number 2

DTIC Science & Technology

1946-12-30

Laboratory personnel working under the direction 0-@. of U. S . Armj Ordnance and General Electric Company personnel. 45. *6 A", ., . . . . __V s ;... r.r.r...thanks are due to U. S . Army ordnance and General Electric Company person- nel for making the fin installation possible and for aid in recovering the...CONDUCTED IN THE-V-2 •....... . . . . . . A. Solar Spectroscopy - F. S . Johnson, J. J. Oberly, C. V. Strain and Re Tousey........ 44 1. Introduction

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

Kitiashvili, I. N.; Couvidat, S.; Lagg, A.

The solar atmosphere is extremely dynamic, and many important phenomena develop on small scales that are unresolved in observations with the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory. For correct calibration and interpretation of the observations, it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables, such as Doppler shift, continuum intensity, spectral line depth, and width. We use 3D radiative hydrodynamics simulations of the upper turbulent convective layer and the atmosphere of the Sun, and a spectro-polarimetric radiative transfer code to study observational characteristics of the Fe imore » 6173 Å line observed by HMI in quiet-Sun regions. We use the modeling results to investigate the sensitivity of the line Doppler shift to plasma velocity, and also sensitivities of the line parameters to plasma temperature and density, and determine effective line formation heights for observations of solar regions located at different distances from the disk center. These estimates are important for the interpretation of helioseismology measurements. In addition, we consider various center-to-limb effects, such as convective blueshift, variations of helioseismic travel-times, and the “concave” Sun effect, and show that the simulations can qualitatively reproduce the observed phenomena, indicating that these effects are related to a complex interaction of the solar dynamics and radiative transfer.« less

Solar forcing - implications for the volatile inventory on Mars and Venus. (Invited)

NASA Astrophysics Data System (ADS)

Lundin, Rickard

2015-04-01

Planets in the solar system are exposed to a persistent solar forcing by solar irradiation and the solar wind. The forcing, most pronounced for the inner Earth-like planets, ionizes, heats, modifies chemically, and gradually erodes the upper atmosphere throughout the lifetime of the planets. Of the four inner planets, the Earth is at present the only one habitable. Our kin Venus and Mars have taken different evolutionary paths, the present lack of a hydrosphere being the most significant difference. However, there are ample evidence for that an early Noachian, water rich period existed on Mars. Similarly, arguments have been presented for an early water-rich period on Venus. The question is, what made Mars and Venus evolve in such a different way compared to the Earth? Under the assumption of similar initial conditions, the planets may have experienced different externally driven episodes (e.g. impacts) with time. Conversely, internal factors on Mars and Venus made them less resilient, unable to sustain solar forcing on an evolutionary time-scale. The latter has been quantified from simulations, combining atmospheric and ionospheric modeling and empiric data from solar-like stars (Sun in time). In a similar way, semi-empirical models based on experimental data were used to determine the mass-loss of volatiles back in time from Mars and Venus. This presentation will review further aspects of semi-empirical modeling based on ion and energetic neutral atom (ENA) escape data from Mars and Venus - on short term (days), mid-term (solar cycle proxies), long-term (Heliospheric flux proxies, 10 000 year), and on time scales corresponding to the solar evolution.

Reply to comment "On the hydrogen escape: Comment to variability of the hydrogen in the Martian upper atmosphere as simulated by a 3D atmosphere-exosphere coupling by J.-Y. Chaufray et al." by V. Krasnopolsky, Icarus, 281, 262

NASA Astrophysics Data System (ADS)

Chaufray, J.-Y.; Gonzalez-Galindo, F.; Forget, F.; Lopez-Valverde, M.; Leblanc, F.; Modolo, R.; Hess, S.

2018-02-01

Krasnopolsky (2017) makes a careful review of our recent results about the Martian hydrogen content of the Martian upper atmosphere (Chaufray et al., 2015). We comment here on his two major points. First, he suggests that the non-thermal escape of H2, and particularly collisions with hot oxygen, not taken into account in our general circulation model (GCM), should modify our reported H2 and H density profiles. This is an important issue; we acknowledge that future effective coupling of our GCM with comprehensive models of the Martian solar wind interaction, ideally after being validated with the latest plasma observations of H2+, would allow for better estimations of the relative importance of the H2 non-thermal and thermal escape processes. For the time being we need assumptions in the GCM, with proper and regular updates. According to a recent and detailed study of the anisotropic elastic and inelastic collision cross sections between O and H2 (Gacesa et al., 2012), the escape rates used by Krasnopolsky (2010) for this process might be overestimated. We therefore do not include non thermal escape of H2 in the model. And secondly, in response to Krasnopolsky's comment on the H escape variability with the solar cycle, we revised our calculations and found a small bug in the computation of the Jeans effusion velocity. Our revised computed H escape rates are included here. They have a small impact on our key conclusions: similar seasonal variations, a reduced variation with the solar cycle but still larger than Krasnopolsky (2017), and again a hydrogen scape systematically lower than the diffusion-limited flux. This bug does not affect the latest Mars Climate Database v5.2.

Volatiles in the Earth and Moon: Constraints on planetary formation and evolution

NASA Astrophysics Data System (ADS)

Parai, Rita

The volatile inventories of the Earth and Moon reflect unique histories of volatile acquisition and loss in the early Solar System. The terrestrial volatile inventory was established after the giant impact phase of accretion, and the planet subsequently settled into a regime of long-term volatile exchange between the mantle and surface reservoirs in association with plate tectonics. Therefore, volatiles in the Earth and Moon shed light on a diverse array of processes that shaped planetary bodies in the Solar System as they evolved to their present-day states. Here we investigate new constraints on volatile depletion in the early Solar System, early outgassing of the terrestrial mantle, and the long-term evolution of the deep Earth volatile budget. We develop a Monte Carlo model of long-term water exchange between the mantle and surface reservoirs. Previous estimates of the deep Earth return flux of water are up to an order of magnitude too large, and incorporation of recycled slabs on average rehydrates the upper mantle but dehydrates the plume source. We find evidence for heterogeneous recycling of atmospheric argon and xenon into the upper mantle from noble gases in Southwest Indian Ridge basalts. Xenon isotope systematics indicate that xenon budgets of mid-ocean ridge and plume-related mantle sources are dominated by recycled atmospheric xenon, though the two sources have experienced different degrees of degassing. Differences between the mid-ocean ridge and plume sources were initiated within the first 100 million years of Earth history, and the two sources have never subsequently been homogenized. New high-precision xenon isotopic data contribute to an emerging portrait of two mantle reservoirs with distinct histories of outgassing and incorporation of recycled material in association with plate tectonics. Xenon isotopes indicate that the Moon likely formed within ˜70 million years of the start of the Solar System. To further investigate early Solar System chronology, we determined strontium isotopic compositions in a suite of planetary materials. If the Moon is derived from proto-Earth material, then rubidium-strontium systematics in the lunar anorthosite 60025 and Moore County plagioclase indicate that Moon formation occurred within ~62 million years of the start of the Solar System.

The effects of a hot outer atmosphere on acoustic-gravity waves

NASA Technical Reports Server (NTRS)

Hindman, Bradley W.; Zweibel, Ellen G.

1994-01-01

We examine the effects of a hot chromosphere and corona on acoustic-gravity waves in the Sun. We use a simple solar model consisting of a neutrally stable polytrope smoothly matched to an isothermal chromosphere or corona. The temperature of the isothermal region is higher than the minimum temperature of the model. We ignore sphericity, magnetic fields, changes in the gravitational potential, and nonadiabatic effects. We find a family of atmospheric g-modes whose cavity is formed by the extremum in the buoyancy frequency at the transition region. The f-mode is the zero-order member of this family. For large values of the harmonic degree l, f-mode frequencies are below the classic f-mode frequency, mu=(gk)(exp 1/2), whereas at small values of l, the f-mode is identical to the classical f-mode solution. We also find a family of g-modes residing in the low chromosphere. Frequency shifts of p-modes can be positive or negative. When the frequency is less than the acoustic cutoff frequency of the upper isothermal atmsophere, the frequency of the upper isothermal atmosphere, the frequency shift is negative, but when the frequency is above this cutoff, the shifts can be positive. High-frequency acoustic waves which are not reflected by the photospheric cutoff are reflected at the corona by the high sound speed for moderate values of l and v. This result is independent of the solar model as long as the corona is very hot. The data are inconsistent with this result, and reasons for this discrepancy are discussed.

Polar Northern Hemisphere Middle Atmospheric Influence due to Energetic Particle Precipitation in January 2005

NASA Technical Reports Server (NTRS)

Jackman, Charles H.

2010-01-01

Solar eruptions and geomagnetic activity led to energetic particle precipitation in early 2005, primarily during the January 16-21 period. Production of OH and destruction of ozone have been documented due to the enhanced energetic solar proton flux in January 2005 [e.g., Verronen et al., Geophys. Res. Lett.,33,L24811,doi:10.1029/2006GL028115, 2006; Seppala et al., Geophys. Res. Lett.,33,L07804, doi:10.1029/2005GL025571,2006]. These solar protons as well as precipitating electrons also led to the production of NO(x) (NO, NO2). Our simulations with the Whole Atmosphere Community Climate Model (WACCM) show that NO(x) is enhanced by 20-50 ppbv in the polar Northern Hemisphere middle mesosphere (approx.60-70 km) by January 18. Both the SCISAT-1 Atmospheric Chemistry Experiment (ACE) NO(x) measurements and Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIP AS) nighttime NO2 observations show large increases during this period, in reasonable agreement with WACCM predictions. Such enhancements are considerable for the mesosphere and led to simulated increases in polar Northern Hemisphere upper stratospheric odd nitrogen (NO(y)) of2-5 ppbv into February 2005. The largest ground level enhancement (GLE) of solar cycle 23 occurred on January 20, 2005 with a neutron monitor increase of about 270 percent [Gopalswamy et al., 29th International Cosmic Ray Conference, Pune,00,101-104,2005]. We found that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced stratospheric NO(y) of less than 1 percent as a result of this GLE. The atmospheric impact of precipitating middle energy electrons (30-2,500 keV) during the January 16-21, 2005 period is also of interest, and an effort is ongoing to include these in WACCM computations. This presentation will show both short- and longer-term changes due to the January 2005 energetic particle precipitation.

MOLECULAR-KINETIC SIMULATIONS OF ESCAPE FROM THE EX-PLANET AND EXOPLANETS: CRITERION FOR TRANSONIC FLOW

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

Johnson, Robert E.; Volkov, Alexey N.; Erwin, Justin T.

The equations of gas dynamics are extensively used to describe atmospheric loss from solar system bodies and exoplanets even though the boundary conditions at infinity are not uniquely defined. Using molecular-kinetic simulations that correctly treat the transition from the continuum to the rarefied region, we confirm that the energy-limited escape approximation is valid when adiabatic expansion is the dominant cooling process. However, this does not imply that the outflow goes sonic. Rather large escape rates and concomitant adiabatic cooling can produce atmospheres with subsonic flow that are highly extended. Since this affects the heating rate of the upper atmosphere andmore » the interaction with external fields and plasmas, we give a criterion for estimating when the outflow goes transonic in the continuum region. This is applied to early terrestrial atmospheres, exoplanet atmospheres, and the atmosphere of the ex-planet, Pluto, all of which have large escape rates.« less

The EISCAT_3D Project in Norway: E3DN

NASA Astrophysics Data System (ADS)

La Hoz, C.; Oksavik, K.

2013-12-01

EISCAT_3D (E3D) is a project to build the next generation of incoherent scatter radars endowed with 3-dimensional scalar and vector capabilities that will replace the current EISCAT radars in Northern Scandinavia. One active (transmitting) site in Norway and four passive (receiving) sites in the Nordic countries will provide 3-D vector imaging capabilities by rapid scanning and multi-beam forming. The unprecedented flexibility of the solid-state transmitter with high duty-cycle, arbitrary wave-forming and polarisation and its pulsed power of 10 MW will provide unrivalled experimental capabilities to investigate the highly non-stationary and non-homogeneous state of the polar upper atmosphere. Aperture Synthesis Imaging Radar (ASIR) will to endow E3D with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. The Norwegian scientific programme is inspired by the pioneer polar scientist Kristian Birkeland (picture) and includes pressing questions on polar upper atmospheric research, among others: (Q1) How to proceed beyond the present simplistic, static, stationary and homogeneous analysis of upper atmospheric and ionospheric processes? (Q2) How does space weather affect ionospheric processes and how to support modelling and space weather services? (Q3) How to advance fundamental plasma physics by employing the ionosphere as a natural plasma physics laboratory? (Q4) How does the influx of extraterrestrial material interact with the upper atmosphere and where does the material originate from? (Q5) How does solar activity couple from geospace into the lower atmosphere and climate system, and does this energy change the wave forcing of geospace from below? Kristian Birkeland, Norwegian scientist and pioneer in polar and auroral research.

Rarefied gas dynamic simulation of transfer and escape in the Pluto-Charon system

NASA Astrophysics Data System (ADS)

Hoey, William A.; Yeoh, Seng Keat; Trafton, Laurence M.; Goldstein, David B.; Varghese, Philip L.

2017-05-01

We apply the direct simulation Monte Carlo rarefied gas dynamic technique to simulations of Pluto's rarefied upper atmosphere motivated by the need to better understand New Horizons (NH) data. We present a novel three-dimensional DSMC model of the atmosphere that spans from several hundred km below the exobase - where continuum flow transitions to the rarefied regime - to fully free-molecular flow hundreds of thousands of km from Pluto's center. We find molecular collisions in Pluto's upper atmosphere to be significant in shaping the flowfield, both by promoting flux from the plutonian exobase to Charon and by increasing the proportion of that flux generated on the exobase's anti-Charon hemisphere. Our model accounts for the gravitational fields of both Pluto and Charon, the centripetal and Coriolis forces due to the rotation of Pluto in our reference frame, and the presence of Charon as a temporary sink for impacting particles. Using this model, we analyze the escape processes of N2 and CH4 from Pluto across different solar heating conditions, and evaluate the three-dimensional structure of the upper plutonian atmosphere, including gas transfer to and deposition on Charon. We find results consistent with the NH-determined escape rate, upper atmospheric temperature, and lack of a detectable Charon atmosphere. Gas-transfer structures are noted in a binary atmospheric configuration, including preferential deposition of material from Pluto's escaping atmosphere onto Charon's leading hemisphere that peaks at 315° E on the equator. As the moon gravitationally focuses incident flow, a high density structure forms in its wake. If molecules are permitted to escape from Charon in diffuse reflections from its surface, a returning flux forms to Pluto's exobase, preferentially directed toward its trailing hemisphere. Charon is capable of supporting a thin atmosphere at column densities as high as 1.5 × 1017 m-2 in simulations with a plutonian exobase condition similar to the NH encounter. Results computed from a fit to the NH encounter exobase (Gladstone et al., 2016) predict a system escape rate of 7 × 1025 CH4 s-1 in close agreement with those reported by NH (Bagenal et al., 2016; Gladstone et al., 2016), and a net depositional flux to Charon of 2 × 1024 s-1, of which ∼98% is methane.

A Reexamination of Deuterium Fractionation on Mars

NASA Astrophysics Data System (ADS)

Pathare, A.; Paige, D. A.

1997-07-01

The ratio of deuterium to hydrogen in the Martian atmosphere is enhanced by a factor of 5 with respect to the terrestrial value, probably due to fractionation associated with thermal Jeans escape from the top of the atmosphere. Theoretical analyses of the relative efficiency of H and D escape have suggested that the deuterium enrichment implies Mars has outgassed the vast majority of its H2O and that the Martian atmosphere is presently not exchanging water with a juvenile reservoir. However, measurements of high and variable D/H values within hydrous minerals in SNC meteorites strongly suggest that mixing between the atmosphere and juvenile water has taken place. Furthermore, the lack of any observed enrichment of atmospheric (18) O with respect to (16) O, in spite of fractionating nonthermal escape mechanisms, indicates buffering by some juvenile source of oxygen, most probably in the form of a surface or subsurface reservoir of water. We propose that this apparent paradox in the interpretation of isotopic hydrogen and oxygen fractionation --or lack thereof-- can be resolved by re-examining the standard model of deuterium fractionation efficiency on Mars. Specifically, we demonstrate the importance of using upper atmospheric temperatures more representative of the range experienced by the Martian exosphere over the course of the solar cycle. Preliminary calculations involving changes in effusion velocity and diffusive separation as a function of exospheric temperature indicate that incorporating these more representative lower exospheric temperatures will reduce the relative efficiency of D escape, in which case the observed enrichment of deuterium can indeed result from exchange with a juvenile source of water. We are in the process of confirming these computations with a one-dimensional upper atmospheric photochemical model that considers the effects of changing solar activity and exospheric temperature on ionospheric composition. If our initial calculations are correct, and the relative efficiency of D escape is low enough to produce the observed D enrichment by exchange with a juvenile reservoir, then attempts to use the present value of atmospheric D/H to infer the total water outgassed by Mars over billions of years would be in error, since the atmospheric D/H would approach its present value in less than a million years of continual exposure to juvenile water.

IRIS Observations of Magnetic Interactions in the Solar Atmosphere between Preexisting and Emerging Magnetic Fields. I. Overall Evolution

NASA Astrophysics Data System (ADS)

Guglielmino, Salvo L.; Zuccarello, Francesca; Young, Peter R.; Murabito, Mariarita; Romano, Paolo

2018-04-01

We report multiwavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the preexisting field of active region NOAA 12529 in the Sun. IRIS data are complemented by full-disk observations of the Solar Dynamics Observatory satellite, relevant to the photosphere and the corona. The photospheric configuration of the EFR is also analyzed by measurements taken with the spectropolarimeter on board the Hinode satellite, when the EFR was fully developed. Recurrent intense brightenings that resemble UV bursts, with counterparts in all coronal passbands, are identified at the edges of the EFR. Jet activity is also observed at chromospheric and coronal levels, near the observed brightenings. The analysis of the IRIS line profiles reveals the heating of dense plasma in the low solar atmosphere and the driving of bidirectional high-velocity flows with speed up to 100 km s‑1 at the same locations. Compared with previous observations and numerical models, these signatures suggest evidence of several long-lasting, small-scale magnetic reconnection episodes between the emerging bipole and the ambient field. This process leads to the cancellation of a preexisting photospheric flux concentration and appears to occur higher in the atmosphere than usually found in UV bursts, explaining the observed coronal counterparts.

Analysis of the UV-B Regime and Potential Effects on Alfalfa

NASA Technical Reports Server (NTRS)

Seitz, Jeffery C.

1998-01-01

Life at the surface of the Earth, over the last 400 m.y., evolved under conditions of decreased short-wave radiation (i.e., ultraviolet) relative to solar output due to absorption and scattering by constituents (e.g., ozone, water vapor, aerosols) in the upper atmosphere. However, a significant amount of ultraviolet radiation in the range from 280-320 nm, known as ultraviolet-B radiation, reaches the Earth's surface and has sufficient energy to be damaging to biologic tissue. Natural fluctuations in atmospheric constituents (seasonal variation, volcanic eruptions, etc.), changes in the orbital attitude of the Earth (precession, axial tilt, orbital eccentricity), and long-term solar variability contribute to changes in the total amount of ultraviolet radiation reaching the surface of the Earth, and thus, the biosphere. More recently, the atmospheric release of commercial propellants and refrigerants, known as chlorofluorocarbons (CFCs), has contributed to a significant depletion in naturally occurring ozone in the stratosphere. Thus, decreased stratospheric ozone has resulted in an increased UV-B flux at the Earth's surface which may have profound effects on terrestrial and marine organisms. In this study, we are investigating the effects of differing solar UV-B fluxes on alfalfa (Medicago sativa L.), an important agricultural crop. A long-term goal of this research is to develop spectral signatures to detect plant response to increased UV-B radiation from remote sensor platforms.

NON-EQUILIBRIUM HELIUM IONIZATION IN AN MHD SIMULATION OF THE SOLAR ATMOSPHERE

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

Golding, Thomas Peter; Carlsson, Mats; Leenaarts, Jorrit, E-mail: thomas.golding@astro.uio.no, E-mail: mats.carlsson@astro.uio.no, E-mail: jorrit.leenaarts@astro.su.se

The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only included non-equilibrium hydrogen ionization by performing a 2D radiation-magnetohydrodynamics simulation featuring non-equilibrium ionization of both hydrogen and helium. The simulation includes the effect of hydrogen Lyα and the EUV radiation from the corona on the ionization and heating of the atmosphere. Details on code implementation are given. We obtain helium ion fractions that are far from their equilibrium values. Comparison with models with local thermodynamicmore » equilibrium (LTE) ionization shows that non-equilibrium helium ionization leads to higher temperatures in wavefronts and lower temperatures in the gas between shocks. Assuming LTE ionization results in a thermostat-like behavior with matter accumulating around the temperatures where the LTE ionization fractions change rapidly. Comparison of DEM curves computed from our models shows that non-equilibrium ionization leads to more radiating material in the temperature range 11–18 kK, compared to models with LTE helium ionization. We conclude that non-equilibrium helium ionization is important for the dynamics and thermal structure of the upper chromosphere and transition region. It might also help resolve the problem that intensities of chromospheric lines computed from current models are smaller than those observed.« less

Method and apparatus for the in situ decontamination of underground water with the aid of solar energy

DOEpatents

Bench, Thomas R.; McCann, Larry D.

1989-01-01

A method for the in situ decontamination of underground water containing -volatile contaminants comprising continuously contacting in situ underground water containing non-volatile contaminants with a liquid-absorbent material possessing high capillary activity, allowing the non-volatile contaminants to deposit in the material while the water moves upwardly through the material by capillary action, allowing substantially decontaminated water to be volatilized by impinging solar radiation, and then allowing the volatilized water to escape from the material into the atmosphere. An apparatus for the in situ decontamination of underground water containing non-volatile contaminants comprising at least one water-impermeable elongated conduit having an upper portion and first and second open ends and containing a homogeneous liquid-absorbent material possessing high capillary activity, means for supporting said conduit, and means for accelerating the escape of the volatilized decontamined water from the material, said means being detachably connected to the second end of the elongated conduit; wherein when underground water contaminated with non-volatile contaminants is continuously contacted in situ with the material contained in the first end of the conduit and the second end of the conduit is placed in contact with atmospheric air, non-volatile contaminants deposit in said material as the water moves upwardly through the material by capillary action, is then volatilized by impinging solar energy and escapes to the atmosphere.

Comparison of precision orbit derived density estimates for CHAMP and GRACE satellites

NASA Astrophysics Data System (ADS)

Fattig, Eric Dale

Current atmospheric density models cannot adequately represent the density variations observed by satellites in Low Earth Orbit (LEO). Using an optimal orbit determination process, precision orbit ephemerides (POE) are used as measurement data to generate corrections to density values obtained from existing atmospheric models. Densities obtained using these corrections are then compared to density data derived from the onboard accelerometers of satellites, specifically the CHAMP and GRACE satellites. This comparison takes two forms, cross correlation analysis and root mean square analysis. The densities obtained from the POE method are nearly always superior to the empirical models, both in matching the trends observed by the accelerometer (cross correlation), and the magnitudes of the accelerometer derived density (root mean square). In addition, this method consistently produces better results than those achieved by the High Accuracy Satellite Drag Model (HASDM). For satellites orbiting Earth that pass through Earth's upper atmosphere, drag is the primary source of uncertainty in orbit determination and prediction. Variations in density, which are often not modeled or are inaccurately modeled, cause difficulty in properly calculating the drag acting on a satellite. These density variations are the result of many factors; however, the Sun is the main driver in upper atmospheric density changes. The Sun influences the densities in Earth's atmosphere through solar heating of the atmosphere, as well as through geomagnetic heating resulting from the solar wind. Data are examined for fourteen hour time spans between November 2004 and July 2009 for both the CHAMP and GRACE satellites. This data spans all available levels of solar and geomagnetic activity, which does not include data in the elevated and high solar activity bins due to the nature of the solar cycle. Density solutions are generated from corrections to five different baseline atmospheric models, as well as nine combinations of density and ballistic coefficient correlated half-lives. These half-lives are varied among values of 1.8, 18, and 180 minutes. A total of forty-five sets of results emerge from the orbit determination process for all combinations of baseline density model and half-lives. Each time period is examined for both CHAMP and GRACE-A, and the results are analyzed. Results are averaged from all solutions periods for 2004--2007. In addition, results are averaged after binning according to solar and geomagnetic activity levels. For any given day in this period, a ballistic coefficient correlated half-life of 1.8 minutes yields the best correlation and root mean square values for both CHAMP and GRACE. For CHAMP, a density correlated half-life of 18 minutes is best for higher levels of solar and geomagnetic activity, while for lower levels 180 minutes is usually superior. For GRACE, 180 minutes is nearly always best. The three Jacchia-based atmospheric models yield very similar results. The CIRA 1972 or Jacchia 1971 models as baseline consistently produce the best results for both satellites, though results obtained for Jacchia-Roberts are very similar to the other Jacchia-based models. Data are examined in a similar manner for the extended solar minimum period during 2008 and 2009, albeit with a much smaller sampling of data. With the exception of some atypical results, similar combinations of half-lives and baseline atmospheric model produce the best results. A greater sampling of data will aid in characterizing density in a period of especially low solar activity. In general, cross correlation values for CHAMP and GRACE revealed that the POE method matched trends observed by the accelerometers very well. However, one period of time deviated from this trend for the GRACE-A satellite. Between late October 2005 and January 2006, correlations for GRACE-A were very low. Special examination of the surrounding months revealed the extent of time this period covered. Half-life and baseline model combinations that produced the best results during this time were similar to those during normal periods. Plotting these periods revealed very short period density variations in the accelerometer that could not be reproduced by the empirical models, HASDM, or the POE method. Finally, densities produced using precision orbit data for the GRACE-B satellite were shown to be nearly indistinguishable from those produced by GRACE-A. Plots of the densities produced for both satellites during the same time periods revealed this fact. Multiple days were examined covering all possible ranges of solar and geomagnetic activity. In addition, the period in which GRACE-A correlations were low was studied. No significant differences existed between GRACE-A and GRACE-B for all of the days examined.

Water, Methane Depletion, and High-Altitude Condensates in the Atmosphere of the Warm Super-Neptune WASP-107b

NASA Astrophysics Data System (ADS)

Kreidberg, Laura; Line, Michael; Thorngren, Daniel; Morley, Caroline; Stevenson, Kevin

2018-01-01

The super-Neptune exoplanet WASP-107b is an exciting target for atmosphere characterization. It has an unusually large atmospheric scale height and a small, bright host star, raising the possibility of precise constraints on its current nature and formation history. In this talk, I will present the first atmospheric study of WASP-107b, a Hubble Space Telescope measurement of its near-infrared transmission spectrum. We determined the planet's composition with two techniques: atmospheric retrieval based on the transmission spectrum and interior structure modeling based on the observed mass and radius. The interior structure models set a 3σ upper limit on the atmospheric metallicity of 30x solar. The transmission spectrum shows strong evidence for water absorption (6.5σ confidence), and we infer a water abundance consistent with expectations for a solar abundance pattern. On the other hand, methane is depleted relative to expectations (at 3σ confidence), suggesting a low carbon-to-oxygen ratio or high internal heat flux. The water features are smaller than predicted for a cloudless atmosphere, crossing less than one scale height. A thick condensate layer at high altitudes (0.1 - 3 mbar) is needed to match the observations; however, we find that it is challenging for physically motivated cloud and haze models to produce opaque condensates at these pressures. Taken together, these findings serve as an illustration of the diversity and complexity of exoplanet atmospheres. The community can look forward to more such results with the high precision and wide spectral coverage afforded by future observing facilities.

Skylab

NASA Image and Video Library

1973-01-01

This montage is a sequence of soft x-ray photographs of the boot-shaped coronal hole rotating with the sun. The individual pictures were taken about 2 days apart by the Skylab telescope. Most of the apparent changes in this 6-day period resulted from a changing perspective. Skylab data helped demonstrate that coronal holes are sources of high-velocity streams in the solar wind. These high-velocity streams can be electrons, protons, and atomic nuclei that spray out from the Sun into interplanetary space. When the coronal hole is near the center of the Sun, as in view 2, the sprinkler is directed at Earth. These high-speed streams of solar wind distort Earth's magnetic field and disturb it's upper atmosphere.

A dynamical perspective on the energetic particles precipitation-middle atmosphere interaction

NASA Astrophysics Data System (ADS)

Karami, Khalil; Sinnhuber, Miriam; Versick, Stefan; Braesicke, Peter

2015-04-01

Energetic particles including protons, electrons and heavier ions, enter the Earth's atmosphere over polar region of both hemispheres, where the geomagnetic lines are considered to be open and connected to the interplanetary medium. This condition allows direct access for energetic particles of solar or galactic origin to directly deposit their own energy into the middle and upper atmosphere. Such particle precipitations can greatly disturb the chemical composition of the upper and middle atmosphere. At polar latitudes, these particles have the potential to penetrate from thermosphere deep into the mesosphere and in rare occasions into the stratosphere. The most important are changes to the budget of atmospheric nitric oxides, NOy, and to atmospheric reactive hydrogen oxides, HOx, which both contribute to ozone loss in the stratosphere and mesosphere. The chemistry-climate general circulation model ECHAM5/MESSy is used to investigate the impact of changed ozone concentration due to energetic particles precipitation on temperatures and wind fields. The simulated anomalies of both zonal mean temperature and zonal wind suggest that these changes are very unlikely to be caused in situ by ozone depletion and indirect dynamical condition is important. The results of our simulations suggests that ozone perturbation is a starting point for a chain of processes resulting in temperature and circulation changes in many areas of the atmosphere. Different dynamical analysis (e.g., frequency of sudden stratospheric warming, dates of stratospheric final warming, divergence of Eliassen-Palm flux and refractive index of planetary waves) are performed to investigate the impact of ozone anomaly originated from high energetic particle precipitation on middle atmospheric temperature and circulation.

Measuring the greenhouse effect and radiative forcing through the atmosphere

NASA Astrophysics Data System (ADS)

Philipona, Rolf; Kräuchi, Andreas; Brocard, Emmanuel

2013-04-01

In spite of a large body of existing measurements of incoming shortwave solar radiation and outgoing longwave terrestrial radiation at the Earth's surface and at the top of the atmosphere, there are few observations documenting how radiation profiles change through the atmosphere - information that is necessary to fully quantify the greenhouse effect of the Earth's atmosphere. Using weather balloons and specific radiometer equipped radiosondes, we continuously measured shortwave and longwave radiation fluxes from the surface of the Earth up to altitudes of 35 kilometers in the upper stratosphere. Comparing radiation profiles from night measurements with different amounts of water vapor, we show evidence of large greenhouse forcing. We show, that under cloud free conditions, water vapor increases with Clausius-Clapeyron ( 7% / K), and longwave downward radiation at the surface increases by 8 Watts per square meter per Kelvin. The longwave net radiation however, shows a positive increase (downward) of 2.4 Watts per square meter and Kelvin at the surface, which decreases with height and shows a similar but negative increase (upward) at the tropopause. Hence, increased tropospheric water vapor increases longwave net radiation towards the ground and towards space, and produces a heating of 0.42 Kelvin per Watt per square meter at the surface. References: Philipona et al., 2012: Solar and thermal radiation profiles and radiative forcing measured through the atmosphere. Geophys. Res. Lett., 39, L13806, doi: 10.1029/2012GL052087.

The role of partial ionization effects in the chromosphere

PubMed Central

Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo; Carlsson, Mats

2015-01-01

The energy for the coronal heating must be provided from the convection zone. However, the amount and the method by which this energy is transferred into the corona depend on the properties of the lower atmosphere and the corona itself. We review: (i) how the energy could be built in the lower solar atmosphere, (ii) how this energy is transferred through the solar atmosphere, and (iii) how the energy is finally dissipated in the chromosphere and/or corona. Any mechanism of energy transport has to deal with the various physical processes in the lower atmosphere. We will focus on a physical process that seems to be highly important in the chromosphere and not deeply studied until recently: the ion–neutral interaction effects in the chromosphere. We review the relevance and the role of the partial ionization in the chromosphere and show that this process actually impacts considerably the outer solar atmosphere. We include analysis of our 2.5D radiative magnetohydrodynamic simulations with the Bifrost code (Gudiksen et al. 2011 Astron. Astrophys. 531, A154 (doi:10.1051/0004-6361/201116520)) including the partial ionization effects on the chromosphere and corona and thermal conduction along magnetic field lines. The photosphere, chromosphere and transition region are partially ionized and the interaction between ionized particles and neutral particles has important consequences on the magneto-thermodynamics of these layers. The partial ionization effects are treated using generalized Ohm's law, i.e. we consider the Hall term and the ambipolar diffusion (Pedersen dissipation) in the induction equation. The interaction between the different species affects the modelled atmosphere as follows: (i) the ambipolar diffusion dissipates magnetic energy and increases the minimum temperature in the chromosphere and (ii) the upper chromosphere may get heated and expanded over a greater range of heights. These processes reveal appreciable differences between the modelled atmospheres of simulations with and without ion–neutral interaction effects. PMID:25897096

Reconstruction of solar UV irradiance since 1974

NASA Astrophysics Data System (ADS)

Krivova, N. A.; Solanki, S. K.; Wenzler, T.; Podlipnik, B.

2009-09-01

Variations of the solar UV irradiance are an important driver of chemical and physical processes in the Earth's upper atmosphere and may also influence global climate. Here we reconstruct solar UV irradiance in the range 115-400 nm over the period 1974-2007 by making use of the recently developed empirical extension of the Spectral And Total Irradiance Reconstruction (SATIRE) models employing Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) data. The evolution of the solar photospheric magnetic flux, which is a central input to the model, is described by the magnetograms and continuum images recorded at the Kitt Peak National Solar Observatory between 1974 and 2003 and by the Michelson Doppler Imager instrument on SOHO since 1996. The reconstruction extends the available observational record by 1.5 solar cycles. The reconstructed Ly-α irradiance agrees well with the composite time series by Woods et al. (2000). The amplitude of the irradiance variations grows with decreasing wavelength and in the wavelength regions of special interest for studies of the Earth's climate (Ly-α and oxygen absorption continuum and bands between 130 and 350 nm) is 1-2 orders of magnitude stronger than in the visible or if integrated over all wavelengths (total solar irradiance).

Reconstruction of solar spectral irradiance since the Maunder minimum

NASA Astrophysics Data System (ADS)

Krivova, N. A.; Vieira, L. E. A.; Solanki, S. K.

2010-12-01

Solar irradiance is the main external driver of the Earth's climate. Whereas the total solar irradiance is the main source of energy input into the climate system, solar UV irradiance exerts control over chemical and physical processes in the Earth's upper atmosphere. The time series of accurate irradiance measurements are, however, relatively short and limit the assessment of the solar contribution to the climate change. Here we reconstruct solar total and spectral irradiance in the range 115-160,000 nm since 1610. The evolution of the solar photospheric magnetic flux, which is a central input to the model, is appraised from the historical record of the sunspot number using a simple but consistent physical model. The model predicts an increase of 1.25 W/m2, or about 0.09%, in the 11-year averaged solar total irradiance since the Maunder minimum. Also, irradiance in individual spectral intervals has generally increased during the past four centuries, the magnitude of the trend being higher toward shorter wavelengths. In particular, the 11-year averaged Ly-α irradiance has increased by almost 50%. An exception is the spectral interval between about 1500 and 2500 nm, where irradiance has slightly decreased (by about 0.02%).

Temperature responses to the 11 year solar cycle in the mesosphere from the 31 year (1979-2010) extended Canadian Middle Atmosphere Model simulations and a comparison with the 14 year (2002-2015) TIMED/SABER observations

NASA Astrophysics Data System (ADS)

Gan, Quan; Du, Jian; Fomichev, Victor I.; Ward, William E.; Beagley, Stephen R.; Zhang, Shaodong; Yue, Jia

2017-04-01

A recent 31 year simulation (1979-2010) by extended Canadian Middle Atmosphere Model (eCMAM30) and the 14 year (2002-2015) observation by the Thermosphere Ionosphere Mesosphere and Dynamics/Sounding of the Atmosphere using Broadband Emssion Radiometry (TIMED/SABER) are utilized to investigate the temperature response to the 11 year solar cycle on the mesosphere. Overall, the zonal mean responses tend to increase with height, and the amplitudes are on the order of 1-2 K/100 solar flux unit (1 sfu = 10-22 W m-2 Hz-1) below 80 km and 2-4 K/100 sfu in the mesopause region (80-100 km) from the eCMAM30, comparatively weaker than those from the SABER except in the midlatitude lower mesosphere. A pretty good consistence takes place at around 75-80 km with a response of 1.5 K/100 sfu within 10°S/N. Also, a symmetric pattern of the responses about the equator agrees reasonably well between the two. It is noteworthy that the eCMAM30 displays an alternate structure with the upper stratospheric cooling and the lower mesospheric warming at midlatitudes of the winter hemisphere, in favor of the long-term Rayleigh lidar observation reported by the previous studies. Through diagnosing multiple dynamical parameters, it is manifested that this localized feature is induced by the anomalous residual circulation as a consequence of the wave-mean flow interaction during the solar maximum year.

Probing Venus' polar upper atmosphere in situ: Preliminary results of the Venus Express Atmospheric Drag Experiment (VExADE).

NASA Astrophysics Data System (ADS)

Rosenblatt, Pascal; Bruinsma, Sean; Mueller-Wodarg, Ingo; Haeusler, Bernd

On its highly elliptical 24 hour orbit around Venus, the Venus Express (VEx) spacecraft briefly reaches a pericenter altitude of nominally 250 km. Recently, however, dedicated and intense radio tracking campaigns have taken place in August 2008 (campaign1), October 2009 (cam-paign2), February and April 2010 (campaign3), for which the pericenter altitude was lowered to about 175 km in order to be able to probe the upper atmosphere of Venus above the North Pole for the first time ever in-situ. As the spacecraft experiences atmospheric drag, its trajectory is measurably perturbed during the pericenter pass, allowing us to infer total atmospheric mass density at the pericenter altitude. The GINS software (Géodésie par Intégration Numérique e e Simultanées) is used to accurately reconstruct the orbital motion of VEx through an iterative least-squares fitting process to the Doppler tracking data. The drag acceleration is modelled using an initial atmospheric density model (VTS model, A. Hedin). A drag scale factor is estimated for each pericenter pass, which scales Hedin's density model in order to best fit the radio tracking data. About 20 density scale factors have been obtained mainly from the second and third VExADE campaigns, which indicate a lower density by a factor of about one-third than Hedin's model predicts. These first ever polar density measurements at solar minimum have allowed us to construct a diffusive equilibrium density model for Venus' thermosphere, constrained in the lower thermosphere primarily by SPICAV-SOIR measurements and above 175 km by the VExADE drag measurements. The preliminary results of the VExADE cam-paigns show that it is possible to obtain reliable estimates of Venus' upper atmosphere densities at an altitude of around 175 km. Future VExADE campaigns will benefit from the planned further lowering of VEx pericenter altitude to below 170 Km.

The response of the temperature of cold-point mesopause to solar activity based on SABER data set

NASA Astrophysics Data System (ADS)

Tang, Chaoli; Liu, Dong; Wei, Heli; Wang, Yingjian; Dai, Congming; Wu, Pengfei; Zhu, Wenyue; Rao, Ruizhong

2016-07-01

The thermal structure and energy balance of upper atmosphere are dominated by solar activity. The response of cold-point mesopause (CPM) to solar activity is an important form. This article presents the response of the temperature of CPM (T-CPM) to solar activity using 14 year Sounding of the Atmosphere using Broadband Emission Radiometry data series over 80°S-80°N regions. These regions are divided into 16 latitude zones with 10° interval, and the spatial areas of 80°S-80°N, 180°W-180°E are divided into 96 lattices with 10°(latitude) × 60°(longitude) grid. The annual-mean values of T-CPM and F10.7 are calculated. The least squares regression method and correlation analysis are applied to these annual-mean series. First, the results show that the global T-CPM is significantly correlated to solar activity at the 0.05 level of significance with correlation coefficient of 0.90. The global solar response of T-CPM is 4.89 ± 0.67 K/100 solar flux unit. Then, for each latitude zone, the solar response of T-CPM and its fluctuation are obtained. The solar response of T-CPM becomes stronger with increasing latitude. The fluctuation ranges of solar response at middle-latitude regions are smaller than those of the equator and high-latitude regions, and the global distribution takes on W shape. The corelationship analysis shows that the T-CPM is significantly correlated to solar activity at the 0.05 level of significance for each latitude zone. The correlation coefficients at middle-latitude regions are higher than those of the equator and high-latitude regions, and the global distribution takes on M shape. At last, for each grid cell, the response of T-CPM to solar activity and their correlation coefficient are presented.

Satellite ozone measurements and the detection of trends

NASA Technical Reports Server (NTRS)

Hilsenrath, Ernest

1990-01-01

Due to the international scientific community's concern with the problem of anthropogenic gas-caused depletion of the ozone layer, an international observational program has been established to conduct stratospheric studies for at least a decade. These observations, which will be performed both by the Space Shuttle and the Upper Atmosphere Research Satellite, will encompass the energy input by solar UV irradiance, source and intermediate gases in ozone chemistry, and the global distributions of these ozone-affecting gases by winds.

High Resolution Observations of Escaping Ions in the Martian Magnetotail

NASA Astrophysics Data System (ADS)

Halekas, J. S.; Raman, C.; Brain, D.; DiBraccio, G. A.; Harada, Y.; McFadden, J. P.; Mitchell, D. L.; Connerney, J. E. P.; Jakosky, B. M.

2016-12-01

Ions escape from the Martian upper atmosphere via a number of channels, including the central plasmasheet of the magnetotail. Mars Express observations show that the heavy ions O+ and O2+ escaping through the central tail often have approximately the same energy, suggesting acceleration in a quasi-static electric field, which has been interpreted as a Hall electric field. The Solar Wind Ion Analyzer (SWIA) on MAVEN was designed to measure the upstream solar wind. However, during orbit segments with appropriate spacecraft attitude, SWIA can also make high resolution measurements of escaping ions in the tail. During the prime mission, these observations were only returned sporadically, during periods of intense escaping fluxes that fortuitously triggered a mode switch. Now, in the extended mission, we return high resolution observations from SWIA routinely. Some of these high resolution measurements reveal slight differences in both the direction and energy of escaping O+ and O2+ ions, which may help determine the acceleration process(es). We investigate the location and solar wind conditions for which the escaping ions separate in energy and angle and the systematics of their energies and flow vectors, and discuss the implications for ion acceleration and the overall picture of Martian atmospheric escape.

Large-scale traveling atmospheric disturbances (LSTADs) in the thermosphere inferred from CHAMP, GRACE, and SETA accelerometer data

NASA Astrophysics Data System (ADS)

Bruinsma, Sean L.; Forbes, Jeffrey M.

2010-08-01

Densities derived from accelerometer measurements on the GRACE, CHAMP, and Air Force/SETA satellites near 490, 390, and 220 km, respectively, are used to elucidate global-scale characteristics of traveling atmospheric disturbances (TADs). Several characteristics elucidated in numerical simulations are confirmed in this study, namely: (1) propagation speeds increase from the lower thermosphere to the upper thermosphere; (2) propagation to the equator and even into the opposite hemisphere can occur; (3) greater attenuation of TADs occurs during daytime and at higher levels of solar activity (i.e., more wave activity during nighttime and solar minimum), presumably due to the greater influence of ion drag. In addition, we find that the occurrence of significant TAD activity emanating from the auroral regions does not reflect a clear relation with the level of planetary magnetic activity as measured by Kp. There is also evidence of waves originating in the tropics, presumably due to convective sources; to some extent this may contribute to the Kp and solar flux relationships noted above. Further elucidation of local time, season, and altitude dependences of TAD propagation characteristics may be forthcoming from density measurements from the GOCE and Swarm missions.

Venus winds at cloud level from VIRTIS during the Venus Express mission

NASA Astrophysics Data System (ADS)

Hueso, Ricardo; Peralta, Javier; Sánchez-Lavega, Agustín.; Pérez-Hoyos, Santiago; Piccioni, Giuseppe; Drossart, Pierre

2010-05-01

The Venus Express (VEX) mission has been in orbit to Venus for almost four years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 μm) map the opacity of the lower cloud deck at 48 km. Here we present our latest results on the analysis of the global atmospheric dynamics at these cloud levels using a large selection over the full VIRTIS dataset. We will show the atmospheric zonal superrotation at these levels and the mean meridional motions. The zonal winds are very stable in the lower cloud at mid-latitudes to the tropics while it shows different signatures of variability in the upper cloud where solar tide effects are manifest in the data. While the upper clouds present a net meridional motion consistent with the upper branch of a Hadley cell the lower cloud present almost null global meridional motions at all latitudes but with particular features traveling both northwards and southwards in a turbulent manner depending on the cloud morphology on the observations. A particular important atmospheric feature is the South Polar vortex which might be influencing the structure of the zonal winds in the lower cloud at latitudes from the vortex location up to 55°S. Acknowledgements This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07.

Towards a complete caracterisation of Ganymede's environnement

NASA Astrophysics Data System (ADS)

Cessateur, Gaël; Barthélémy, Mathieu; Lilensten, Jean; Dudok de Wit, Thierry; Kretzschmar, Matthieu; Mbemba Kabuiku, Lydie

2013-04-01

In the framework to the JUICE mission to the Jovian system, a complete picture of the interaction between Ganymede's atmosphere and external forcing is needed. This will definitely allow us to constrain instrument performances according to the mission objectives. The main source of information regarding the upper atmosphere is the non LTE UV-Visible-near IR emissions. Those emissions are both induce by the incident solar UV flux and particle precipitations. This work aims at characterizing the impact from those external forcing, and then at deriving some key physical parameters that are measurable by an orbiter, namely the oxygen red line at 630 nm or the resonant oxygen line at 130 nm for example. We will also present the 4S4J instrument, a proposed EUV radiometer, which will provides the solar local EUV flux, an invaluable parameter for the JUICE mission. Based on new technologies and a new design, only two passbands are considered for reconstructing the whole EUV spectrum.

Solar polarimetry through the K I lines at 770 nm

NASA Astrophysics Data System (ADS)

Quintero Noda, C.; Uitenbroek, H.; Katsukawa, Y.; Shimizu, T.; Oba, T.; Carlsson, M.; Orozco Suárez, D.; Ruiz Cobo, B.; Kubo, M.; Anan, T.; Ichimoto, K.; Suematsu, Y.

2017-09-01

We characterize the K I D1 & D2 lines in order to determine whether they could complement the 850 nm window, containing the Ca II infrared triplet lines and several Zeeman sensitive photospheric lines, that was studied previously. We investigate the effect of partial redistribution on the intensity profiles, their sensitivity to changes in different atmospheric parameters, and the spatial distribution of Zeeman polarization signals employing a realistic magnetohydrodynamic simulation. The results show that these lines form in the upper photosphere at around 500 km, and that they are sensitive to the line-of-sight velocity and magnetic field strength at heights where neither the photospheric lines nor the Ca II infrared lines are. However, at the same time, we found that their sensitivity to the temperature essentially comes from the photosphere. Then, we conclude that the K I lines provide a complement to the lines in the 850 nm window for the determination of atmospheric parameters in the upper photosphere, especially for the line-of-sight velocity and the magnetic field.

Understanding of Jupiter's Atmosphere After the Galileo Probe Entry

NASA Technical Reports Server (NTRS)

Young, Richard E.; DeVincenzi, Donald (Technical Monitor)

2001-01-01

Instruments on the Galileo probe measured composition, cloud properties, thermal structure. winds, radiative energy balance, and electrical properties of the Jovian atmosphere. As expected the probe results confirm some expectations about Jupiter's atmosphere, refute others, and raise new questions which still remain unanswered. This talk will concentrate on those aspects of the probe observations which either raised new questions or remain unresolved. The Galileo probe observations of composition and clouds provided some of the biggest surprises of the mission. Helium abundance measured by the probe differed significantly from the remote sensing derivations from Voyager. discrepancy between the Voyager helium abundance determinations for Jupiter and the Galileo probe value have now led to a considerably increased helium determination for Saturn. Global abundance of N in the form of ammonia was observed to be supersolar by approximately the same factor as carbon, in contrast to expectations that C/N would be significantly larger than solar. This has implications for the formation and evolution of Jupiter. The cloud structure was not what was generally anticipated, even though most previous remote sensing results below the uppermost cloud referred to 5 micron hot spots, local regions with reduced cloud opacity. The Galileo probe descended in one of these hot spots. Only a tenuous, presumed ammonium hydrosulfide, cloud was detected, and no significant water cloud or super-solar water abundance was measured. The mixing ratios as a function of depth for the condensibles ammonia, hydrogen sulfide, and water, exhibited no apparent correlation with either condensation levels or with each other, an observation that is still a puzzle, although there are now dynamical models of hot spots which show promise in being able to explain such behavior. Probe tracked zonal winds show that wind magnitude increases with depth to pressures of about 4 bars, with the winds extending to at least as deep as the probe made measurements, 22 bars. Models of hot spot dynamics raise the possibility that the variation with depth of the probe measured zonal winds between 0.4 and 4 bars reflect the dynamics of the hot spot rather than the global wind pattern. Galileo upper atmosphere measurements established that there is a sharp temperature rise with altitude between about 350 and 800 km above the 1 bar pressure level, with the upper atmosphere reaching, temperatures near 900 K. The energy sources for this upper atmosphere heating are not clearly established, but various mechanisms have been proposed. These and other aspects of the Galileo probe data will be discussed.

An overview of atmosphere and plasma observations planned for the New Horizons flyby of 2014 MU69

NASA Astrophysics Data System (ADS)

Gladstone, R.; Young, L. A.; Parker, J. W.; Elliott, H. A.; Hill, M. E.; Piquette, M. R.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Spencer, J. R.

2017-12-01

Due to its small size, it is highly likely that all volatiles that might have once been present on 2014 MU69 are now gone, having long ago escaped to space. However, it is possible that 2014 MU69 retains some volatiles (e.g., methanol, acetylene, ethane, hydrogen cyanide, ammonia) at the present day. Although these volatiles are likely quite stable on the surface at their current temperature, ongoing radiation processing and occasional impacts provide a possible source for a transient atmosphere. Such a transient atmosphere will be searched for by the Alice ultraviolet spectrograph, e.g., in absorption, using stellar and solar appulses, and in emission, using resonantly scattered solar emissions. Dust associated with 2014 MU69 will be searched for with high phase angle LORRI and MVIC imaging, and with in situ SDC observations. In addition, the particle and plasma environment of KBOs is largely unknown. SWAP and PEPSSI observations will establish the interaction of the interplanetary medium with 2014 MU69, e.g., looking for pickup ions resulting from sputtering of surface materials. Although it is likely that only upper limits will be set on neutrals and ions in the vicinity of 2014 MU69, the New Horizons observations will characterize the fluxes of UV, solar wind, interstellar pickup ions, and energetic particles, i.e., space weathering, that can modify the surface of 2014 MU69 and other KBOs. In this presentation, we will outline the plans for New Horizons plasma and atmospheres observations during the flyby of 2014 MU69.

Solar and Space Physics: A Science for a Technological Society

NASA Technical Reports Server (NTRS)

2013-01-01

From the interior of the Sun, to the upper atmosphere and near-space environment of Earth, and outward to a region far beyond Pluto where the Sun's influence wanes, advances during the past decade in space physics and solar physics the disciplines NASA refers to as heliophysics have yielded spectacular insights into the phenomena that affect our home in space. This report, from the National Research Council's (NRC's) Committee for a Decadal Strategy in Solar and Space Physics, is the second NRC decadal survey in heliophysics. Building on the research accomplishments realized over the past decade, the report presents a program of basic and applied research for the period 2013-2022 that will improve scientific understanding of the mechanisms that drive the Sun's activity and the fundamental physical processes underlying near-Earth plasma dynamics, determine the physical interactions of Earth's atmospheric layers in the context of the connected Sun-Earth system, and enhance greatly the capability to provide realistic and specific forecasts of Earth's space environment that will better serve the needs of society. Although the recommended program is directed primarily to NASA (Science Mission Directorate -- Heliophysics Division) and the National Science Foundation (NSF) (Directorate for Geosciences -- Atmospheric and Geospace Sciences) for action, the report also recommends actions by other federal agencies, especially the National Oceanic and Atmospheric Administration (NOAA) those parts of NOAA charged with the day-to-day (operational) forecast of space weather. In addition to the recommendations included in this summary, related recommendations are presented in the main text of the report.

NASA's Best-Observed X-Class Flare of All Time

NASA Image and Video Library

2014-05-07

The March 29, 2014, X-class flare appears as a bright light on the upper right in this image from SDO, showing light in the 304 Angstrom wavelength. This wavelength shows material on the sun in what's called the transition region, where the chromosphere transitions into the upper solar atmosphere, the corona. Some light of the flare is clearly visible, but the flare appears brighter in other images that show hotter temperature material. Credit: NASA/SDO/AIA -- On March 29, 2014 the sun released an X-class flare. It was observed by NASA's Interface Region Imaging Spectrograph, or IRIS; NASA's Solar Dynamics Observatory, or SDO; NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager, or RHESSI; the Japanese Aerospace Exploration Agency's Hinode; and the National Solar Observatory's Dunn Solar Telescope located at Sacramento Peak in New Mexico. To have a record of such an intense flare from so many observatories is unprecedented. Such research can help scientists better understand what catalyst sets off these large explosions on the sun. Perhaps we may even some day be able to predict their onset and forewarn of the radio blackouts solar flares can cause near Earth - blackouts that can interfere with airplane, ship and military communications. Read more: 1.usa.gov/1kMDQbO Join our Google+ Hangout on May 8 at 2:30pm EST: go.nasa.gov/1mwbBEZ NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Extreme ultraviolet spectral irradiance measurements since 1946

NASA Astrophysics Data System (ADS)

Schmidtke, G.

2015-03-01

In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and long-term scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5% and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial irradiance camera (STI-Cam) and also be used investigating real-time space weather effects and deriving more detailed correction procedures for the evaluation of Global Navigation Satellite System (GNSS) signals. Progress in physics goes with achieving higher accuracy in measurements. This review historically guides the reader on the ways of exploring the impact of the variable solar radiation in the extreme ultraviolet spectral region on our upper atmosphere in the altitude regime from 80 to 1000 km.

Science of Opportunity: Heliophysics on the FASTSAT Mission and STP-S26

NASA Technical Reports Server (NTRS)

Rowland, Douglas E.; Collier, Michael R.; Sigwarth, John B.; Jones, Sarah L.; Hill, Joanne K.; Benson, Robert; Choi, Michael; Chornay, Dennis; Cooper, John; Feng, Steven;