Science.gov

Sample records for advanced ionospheric sounder

  1. Topside sounders as mobile ionospheric heaters

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    2006-01-01

    There is evidence that satellite-borne RF sounders can act as mobile ionospheric heaters in addition to performing topside sounding. The main objective of topside sounding is to use sounder-generated electromagnetic (em) waves to obtain ionospheric topside vertical electron-density (N(sub e) profiles. These profiles are obtained from mathematical inversions of the frequency vs. delay-time ionospheric reflection traces. In addition to these em reflection traces, a number of narrowband intense signals are observed starting at zero delay times after the transmitted pulses. Some of these signals, termed plasma resonances, appear at characteristic frequencies of the ambient medium such as at the electron cyclotron frequency f(sub ce), the harmonics nf(sub ce), the electron plasma frequency f(sub pe) and the upper-hybrid frequency f(sub uh), where (f(sub uh))(exp 2) = (f(sub ce))(exp 2) + (f(sub pe))(exp 2) . These signals have been attributed to the oblique echoes of sounder-generated electrostatic (es) waves. These resonances provide accurate in situ f(sub pe) and f(sub ce) values which, in turn, lead to accurate N(sub e) and [B] values where B is the ambient magnetic field. Resonances are also observed between the nf(sub ce) harmonics both above and below f(sub uh). The former, known as the Qn plasma resonances, are mainly attributed to the matching of the wave group velocity of sounder-generated (Bernstein-mode) es waves to the satellite velocity. The frequency spectrum of these waves in the magnetosphere can be used to detect non-Maxwellian electron velocity-distributions. In addition, these resonances also exhibit components that appear to be the result of plasma emissions stimulated by the sounder pulses. The plasma resonances observed between the nf(sub ce) harmonics and below f(sub uh), known as the Dn plasma resonances, are entirely attributed to such sounder-stimulated plasma emissions. There are other sounder-stimulated plasma phenomena that also fall into

  2. Results of the international ionospheric Doppler sounder network

    NASA Astrophysics Data System (ADS)

    Lastovicka, Jan; Chum, Jaroslav

    2016-07-01

    This paper summarizes main recent results reached by the Czech-lead international network of ionospheric Doppler sounders. The network consists of Doppler sounders in the western half of Czechia (5 measuring paths, 3 frequencies with central receivers in Prague), northern Taiwan (3 transmitters, two separated receivers, 1 frequency), and three similar systems (3 measuring paths with 1 receiver and 1 frequency) in Tucuman (north-western Argentina), Hermanus (the southernmost South Africa) and Luisville (northern South Africa). Three main areas of research have been (1) statistical properties of gravity waves, (2) ionospheric effects of earthquakes, and (3) low latitude/equatorial phenomena. Some results: (1) the theoretically expected dominance of gravity wave propagation against wind has been confirmed; (2) impact of the Tohoku 2001 M9.0 earthquake was registered in the ionosphere over the Czech Republic as long-period infrasound on the distance of about 9000 km from epicenter; analysis of ionospheric infrasound excited by the Nepal 2015 M7.8 earthquake observed by the Czech and Taiwan Doppler sounders showed that the intensity of ionospheric signal is significantly height dependent and that the Doppler shift depends not only on the advection (up and down motion) of the reflecting layer but also on the compression/rarefaction of the electron gas; (3) spread F structures observed by Doppler sounders in Tucuman and Taiwan (both under the crest of equatorial ionization anomaly) provide results consistent with S4 scintillation data and with previous optical, GPS and satellite measurements.

  3. Design of a flexible and low-power ionospheric sounder

    NASA Astrophysics Data System (ADS)

    Morris, Alex

    Characterizing the structure of the ionosphere has practical applications for telecommunications and scientific applications for studies of the near-Earth space environment. Among several methods for measuring parameters of the ionosphere is ionospheric sounding, a radar technique that determines the electron content of the ionosphere as a function of height. Various research, military, and commercial institutions operate hundreds of ground-based ionosondes throughout the globe, and new ionosondes continue to be deployed in increasingly remote and distant locations. This thesis presents the design of an ionospheric sounder that reduces the power, size, and cost compared to existing systems. Key improvements include the use of an open-source software-defined radio platform and channel-aware dynamic sounding scheduling.

  4. The DST group ionospheric sounder replacement for JORN

    NASA Astrophysics Data System (ADS)

    Harris, T. J.; Quinn, A. D.; Pederick, L. H.

    2016-06-01

    The Jindalee Over-the-horizon Radar Network (JORN) is an integral part of Australia's national defense capability. JORN uses a real-time ionospheric model as part of its operations. The primary source of data for this model is a set of 13 vertical-incidence sounders (VIS) scattered around the Australian coast and inland locations. These sounders are a mix of Lowell digisonde portable sounder (DPS)-1 and DPS-4. Both of these sounders, the DPS-1 in particular, are near the end of their maintainable life. A replacement for these aging sounders was required as part of the ongoing sustainment program for JORN. Over the last few years the High-Frequency Radar Branch (HFRB) of the Defence Science and Technology (DST) Group, Australian Department of Defence, has been developing its own sounders based on its successful radar hardware technology. The DST Group VIS solution known as PRIME (Portable Remote Ionospheric Monitoring Equipment) is a 100% duty cycle, continuous wave system that receives the returned ionospheric signal while it is still transmitting and operates the receiver in the near field of the transmitter. Of considerable importance to a successful VIS is the autoscaling software, which takes the ionogram data and produces an ionogram trace (group delay as a function of frequency), and from that produces a set of ionospheric parameters that represent the (bottomside) overhead electron density profile. HFRB has developed its own robust autoscaling software. The performance of DST Group's PRIME under a multitude of challenging ionospheric conditions has been studied. In December 2014, PRIME was trialed at a JORN VIS site collocated with the existing Lowell Digisonde DPS-1. This side-by-side testing determined that PRIME was fit for purpose. A summary of the results of this comparison and example PRIME output will be discussed. Note that this paper compares PRIME with the 25 year old Lowell Digisonde DPS-1, which is planned to be replaced. Our future plans include

  5. Influence of geophysical factors on oblique-sounder ionospheric characteristics

    SciTech Connect

    Baranets, A.N.; Blagoveshchenskaya, N.F.; Borisova, T.D.; Bubnov, V.A.

    1988-10-01

    The purpose of this paper is to study the influence of geophysical factors, including magnetoionospheric disturbances, on decameter wave propagation over extended paths using oblique sounding (OS) data, and also to compare experimental and calculated OS ionograms for various conditions of radio waver propagation (season, time of day). Variations of oblique-sounder ionospheric characteristics along a 9000 km long subauroral path for various geophysical conditions are considered. A comparison is made of experimental and calculated ionograms of oblique sounding.

  6. Advanced Atmospheric Sounder and Imaging Radiometer (AASIR)

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Design information for the Advanced Atmospheric Sounder and Imaging Radiometer is reported, which was developed to determine the configuration of a sensor for IR and visible imaging. The areas of technology reported include: systems design, optics, mechanics, electronics, detectors, radiative cooler, and radiometric calibration.

  7. Advanced microwave sounding unit study for atmospheric infrared sounder

    NASA Technical Reports Server (NTRS)

    Rosenkranz, Philip W.; Staelin, David H.

    1992-01-01

    The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU-A), and the Microwave Humidity Sounder (MHS, formerly AMSU-B) together constitute the advanced sounding system facility for the Earth Observing System (EOS). A summary of the EOS phase B activities are presented.

  8. Advanced Meteorological Temperature Sounder (AMTS) study

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The results of a system definition study (theoretical) for an Advanced Meteorological Temperature Sounder (AMTS) is described. From the data the atmospheric temperature and humidity profiles can be determined over the entire earth's surface with a spatial resolution of 45 km. x 45 km; amounts and type of cloud cover as well as surface temperatures of the earth are also determined. The major purpose of the study was to determine the feasibility of cooling twenty-eight detectors to the 80-90 Kelvin region by means of a radiative cooler. Other related considerations were achieving high signal-to-noise ratios, maximizing optical throughput through the grating spectrometer, and reducing preamplifier noise. A detailed optical design of an f/5 Ebert-Fastie spectrometer was carried out to verify that image quality is adequate; field lenses near the spectrometer focal plane were designed to image the grating onto the smallest size detectors for each channel.

  9. Spectral Resolution and Coverage Impact on Advanced Sounder Information Content

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Liu, Xu; Zhou, Daniel K.; Smith, William L.

    2010-01-01

    Advanced satellite sensors are tasked with improving global measurements of the Earth s atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Achieving such measurement improvements requires instrument system advancements. This presentation focuses on the impact of spectral resolution and coverage changes on remote sensing system information content, with a specific emphasis on thermodynamic state and trace species variables obtainable from advanced atmospheric sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and Cross-track Infrared Sounder (CrIS) systems on the MetOp and NPP/NPOESS series of satellites. Key words: remote sensing, advanced sounders, information content, IASI, CrIS

  10. Ducted electromagnetic waves in the Martian ionosphere detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenfei; Orosei, Roberto; Huang, Qian; Zhang, Jie

    2016-07-01

    In the data of the Mars Advanced Radar for Subsurface and Ionosphere Sounding on board the European Space Agency (ESA) mission Mars Express (MEX), a distinctive type of signals (called the "epsilon signature"), which is similar to that previously detected during radio sounding of the terrestrial F region ionosphere, is found. The signature is interpreted to originate from multiple reflections of electromagnetic waves propagating along sounder pulse-created, crustal magnetic field-aligned plasma bubbles (waveguides). The signatures have a low (below 0.5%) occurrence rate and apparent cutoff frequencies 3-5 times higher than the theoretical one for an ordinary mode wave. These properties are explained by the influence of the perpendicular ionospheric plasma density gradient and the sounder pulse frequency on the formation of waveguides.

  11. Geophysical Information from Advanced Sounder Infrared Spectral Radiance

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Zhou, Daniel K.; Liu, Xu; Smith, William L.

    2012-01-01

    Advanced satellite sensors are tasked with improving global observations of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Satisfying this type of improvement for inferred geophysical information from these observations requires optimal usage of data from current systems as well as enhancements to future sensors. This presentation addresses the information content present in infrared spectral radiance from advanced atmospheric sounders with an emphasis on knowledge of thermodynamic state and trace species. Results of trade-off studies conducted to evaluate the impact of spectral resolution, spectral coverage, instrument noise, and a priori knowledge on remote sensing system information content will be discussed. A focus is placed on information achievable from the Atmospheric InfraRed Sounder (AIRS) on the NASA EOS Aqua satellite in orbit since 2002, the Infrared Atmospheric Sounding Interferometer (IASI) aboard MetOp-A since 2006, and the Cross-track Infrared Sounder (CrIS) instrument aboard the NPP and JPSS series of satellites which began 28 October 2011.

  12. Estimation of the Total Electron Content of the Martian Ionosphere using Radar Sounder Surface Echoes

    NASA Technical Reports Server (NTRS)

    Safaeinili, Ali; Kofman, Wlodek; Mouginot, Jeremie; Gim, Yonggyu; Herique, Alain; Ivanov, Anton B.; Plaut, Jeffrey J.; Picardi, Giovanni

    2007-01-01

    The Martian ionosphere's local total electron content (TEC) and the neutral atmosphere scale height can be derived from radar echoes reflected from the surface of the planet. We report the global distribution of the TEC by analyzing more than 750,000 echoes of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS). This is the first direct measurement of the TEC of the Martian ionosphere. The technique used in this paper is a novel 'transmission-mode' sounding of the ionosphere of Mars in contrast to the Active Ionospheric Sounding experiment (AIS) on MARSIS, which generally operates in the reflection mode. This technique yields a global map of the TEC for the Martian ionosphere. The radar transmits a wideband chirp signal that travels through the ionosphere before and after being reflected from the surface. The received waves are attenuated, delayed and dispersed, depending on the electron density in the column directly below the spacecraft. In the process of correcting the radar signal, we are able to estimate the TEC and its global distribution with an unprecedented resolution of about 0.1 deg in latitude (5 km footprint). The mapping of the relative geographical variations in the estimated nightside TEC data reveals an intricate web of high electron density regions that correspond to regions where crustal magnetic field lines are connected to the solar wind. Our data demonstrates that these regions are generally but not exclusively associated with areas that have magnetic field lines perpendicular to the surface of Mars. As a result, the global TEC map provides a high-resolution view of where the Martian crustal magnetic field is connected to the solar wind. We also provide an estimate of the neutral atmospheric scale height near the ionospheric peak and observe temporal fluctuations in peak electron density related to solar activity.

  13. Impact of Measurement System Characteristics on Advanced Sounder Information Content

    NASA Technical Reports Server (NTRS)

    Larar, Allen M.; Liu, Xu; Zhou, Daniel K.

    2011-01-01

    Advanced satellite sensors are tasked with improving global observations of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Achieving such an improvement in geophysical information inferred from these observations requires optimal usage of data from current systems as well as instrument system enhancements for future sensors. This presentation addresses results of tradeoff studies evaluating the impact of spectral resolution, spectral coverage, instrument noise, and a priori knowledge on remote sensing system information content, with a specific emphasis on thermodynamic state and trace species information obtainable from advanced atmospheric sounders. Particular attention will be devoted toward information achievable from the Atmospheric InfraRed Sounder (AIRS) on the NASA EOS Aqua satellite in orbit since 2002, the Infrared Atmospheric Sounding Interferometer (IASI) aboard MetOp-A since 2006, and the Cross-track Infrared Sounder (CrIS) instrument to fly aboard the NPP and JPSS series of satellites expected to begin in late 2011. While all of these systems cover nearly the same infrared spectral extent, they have very different number of channels, instrument line shapes, coverage continuity, and instrument noise. AIRS is a grating spectrometer having 2378 discrete spectral channels ranging from about 0.4 to 2.2/cm resolution; IASI is a Michelson interferometer with 8461 uniformly-spaced spectral channels of 0.5/cm (apodized) resolution; and CrIS is a Michelson interferometer having 1305 spectral channels of 0.625, 1.250, and 2.50/cm (unapodized) spectral resolution, respectively, over its three continuous but non-overlapping bands. Results of tradeoff studies showing information content sensitivity to assumed measurement system characteristics will be presented.

  14. Alouette and ISIS topside sounder measurements -A data source for improvements of the IRI model in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Bilitza, Dieter; Benson, Robert; Reinisch, Bodo; Huang, Xueqin

    The Alouette and ISIS topside sounder satellites recorded a great wealth of information about the topside ionosphere during their long period of operations (from 1962 to 1990). So much though that only a small percentage was analyzed during the mission life time. The soundings were stored on more than 100,000 seven-track analog telemetry tapes. In the mid-nineties space limitations and storage costs threatened an imminent loss of these tapes. Only a last minute intervention spear-headed by NASA's Ionosphere, Thermosphere, Mesosphere (ITM) Data Evaluation Panel saved a significant portion of these tapes and with funding from the AISRP program these data were first digitized and then converted into electron density profiles. This data restoration effort more than tripled the Alouette/ISIS topside sounder data base and has led to significant improvements of models for the topside ionosphere, e.g., about a factor of 2 improvement in the case of the IRI-2007 topside electron density profile. We will present a brief history of this successful data restoration effort and its current status. The homepage for the ISIS project is at http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html.

  15. Two classes of medium-scale traveling ionospheric disturbances observed with an array on HF-Doppler sounders

    NASA Technical Reports Server (NTRS)

    Shibata, T.; Okuzawa, T.

    1985-01-01

    The importance of the quasi-evanescent mode of acoustic-gravity waves (AGW) was recently stressed to elaborate on the daytime dispersion characteristics of horizontal velocity of medium-scale traveling ionospheric disturbances (MS-TID) which were observed by a high frequency Doppler (HFD) sounder array in central Japan. Observed MS-TIDs were classified into two categories: the internal mode and the quasi-evanescent mode as regards physical implication. Nonlinear wave-wave interaction is proposed in an attempt to explain salient features of the latter-class TID.

  16. Automatic ionospheric layers detection: Algorithms analysis

    NASA Astrophysics Data System (ADS)

    Molina, María G.; Zuccheretti, Enrico; Cabrera, Miguel A.; Bianchi, Cesidio; Sciacca, Umberto; Baskaradas, James

    2016-03-01

    Vertical sounding is a widely used technique to obtain ionosphere measurements, such as an estimation of virtual height versus frequency scanning. It is performed by high frequency radar for geophysical applications called ;ionospheric sounder; (or ;ionosonde;). Radar detection depends mainly on targets characteristics. While several targets behavior and correspondent echo detection algorithms have been studied, a survey to address a suitable algorithm for ionospheric sounder has to be carried out. This paper is focused on automatic echo detection algorithms implemented in particular for an ionospheric sounder, target specific characteristics were studied as well. Adaptive threshold detection algorithms are proposed, compared to the current implemented algorithm, and tested using actual data obtained from the Advanced Ionospheric Sounder (AIS-INGV) at Rome Ionospheric Observatory. Different cases of study have been selected according typical ionospheric and detection conditions.

  17. Assimilation of thermodynamic information from advanced infrared sounders under partially cloudy skies for regional NWP

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Li, Jun; Goldberg, Mitchell D.; Schmit, Timothy J.; Lim, Agnes H. N.; Li, Zhenglong; Han, Hyojin; Li, Jinlong; Ackerman, Steve A.

    2015-06-01

    Generally, only clear-infrared spectral radiances (not affected by clouds) are assimilated in weather analysis systems. This is due to difficulties in modeling cloudy radiances as well as in observing their vertical structure from space. To take full advantage of the thermodynamic information in advanced infrared (IR) sounder observations requires assimilating radiances from cloud-contaminated regions. An optimal imager/sounder cloud-clearing technique has been developed by the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin-Madison. This technique can be used to retrieve clear column radiances through combining collocated multiband imager IR clear radiances and the sounder cloudy radiances; no background information is needed in this method. The imager/sounder cloud-clearing technique is similar to that of the microwave/IR cloud clearing in the derivation of the clear-sky equivalent radiances. However, it retains the original IR sounder resolution, which is critical for regional numerical weather prediction applications. In this study, we have investigated the assimilation of cloud-cleared IR sounder radiances using Atmospheric Infrared Sounder (AIRS)/Moderate Resolution Imaging Spectroradiometer for three hurricanes, Sandy (2012), Irene (2011), and Ike (2008). Results show that assimilating additional cloud-cleared AIRS radiances reduces the 48 and 72 h temperature forecast root-mean-square error by 0.1-0.3 K between 300 and 850 hPa. Substantial improvement in reducing track forecasts errors in the range of 10 km to 50 km was achieved.

  18. Single Site Location with Ionospheric Specification from Oblique-Incidence Sounders.

    DTIC Science & Technology

    2014-09-26

    the sounder network has been made. Several tasks remain in the analysis of SSL- ICT data. Several of the other time periods in the data base can be...0, - , . , * - - 6 Elt -,R W CL CL a. a. a. a. a. a. I I * et I, 14 -NAI.,N I if. APPENDIX C Plots of tinV2 vs. cosx

  19. Ionosphere Explorer I Satellite: First Observations from the Fixed-Frequency Topside Sounder.

    PubMed

    Calvert, W; Knecht, R W; Vanzandt, T E

    1964-10-16

    The satellite has yielded new information on the arrangement of irregularities in sheets and the structure of plasma resonances in the ionosphere. Studies of the geographical distributions of the different kinds of spread F, sporadic E, and other phenomena will be facilitated by the satellite. More phenomena will undoubtedly be recognized as the records are studied.

  20. Advanced infrared sounder subpixel cloud detection with imagers and its impact on radiance assimilation in NWP

    NASA Astrophysics Data System (ADS)

    Wang, Pei; Li, Jun; Li, Jinlong; Li, Zhenglong; Schmit, Timothy J.; Bai, Wenguang

    2014-03-01

    Accurate cloud detection is very important for infrared (IR) radiance assimilation; improved cloud detection could reduce cloud contamination and hence improve the assimilation. Although operational numerical weather prediction (NWP) centers are using IR sounder radiance data for cloud detection, collocated high spatial resolution imager data could help sounder subpixel cloud detection and characterization. IR sounder radiances with improved cloud detection using Atmospheric Infrared Sounder (AIRS)/Moderate Resolution Imaging Spectroradiometer (MODIS) were assimilated for Hurricane Sandy (2012). Forecast experiments were run with Weather Research and Forecasting (WRF) as the forecast model and the Three-Dimensional Variational Assimilation (3DVAR)-based Gridpoint Statistical Interpolation (GSI) as the analysis system. Results indicate that forecasts of both hurricane track and intensity are substantially improved when the collocated high spatial resolution MODIS cloud mask is used for AIRS subpixel cloud detection for assimilating radiances. This methodology can be applied to process Crosstrack Infrared Sounder (CRIS)/Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPOESS Preparatory Project (NPP)/Joint Polar Satellite System (JPSS) and Infrared Atmospheric Sounding Interferometer (IASI)/Advanced Very High Resolution Radiometer (AVHRR) onboard the Metop series for improved radiance assimilation in NWP.

  1. Limb sounders tracking topographic gravity wave activity from the stratosphere to the ionosphere around midlatitude Andes

    NASA Astrophysics Data System (ADS)

    Alexander, P.; Torre, A.; Schmidt, T.; Llamedo, P.; Hierro, R.

    2015-10-01

    Several studies have shown that the surroundings of the highest Andes mountains at midlatitudes in the Southern Hemisphere exhibit gravity waves (GWs) generated by diverse sources which may traverse the troposphere and then penetrate the upper layers if conditions are favorable. There is a specific latitude band where that mountain range is nearly perfectly aligned with the north-south direction, which favors the generation of wavefronts parallel to this orientation. This fact may allow an optimization of procedures to identify topographic GW in some of the observations. We analyze data per season to the east and west of these Andes latitudes to find possible significant differences in GW activity between both sectors. GW effects generated by topography and convection are expected essentially on the eastern side. We use satellite data from two different limb sounding methods: the Global Positioning System radio occultation (RO) technique and the Sounding of the Atmosphere using Broadband Emission Radiometry instrument, which are complementary with respect to the height intervals, in order to study the effects of GW from the stratosphere to the ionosphere. Activity becomes quantified by the GW average potential energy in the stratosphere and mesosphere and by the electron density variance content in the ionosphere. Consistent larger GW activity on the eastern sector is observed from the stratosphere to the ionosphere (night values). However, this fact remains statistically significant at the 90% significance level only during winter, when GWs generated by topography dominate the eastern sector. On the contrary, it is usually assumed that orographic GWs have nearly zero horizontal phase speed and will therefore probably be filtered at some height in the neutral atmosphere. However, this scheme relies on the assumption that the wind is uniform and constant. Our results also suggest that it is advisable to separate night and day cases to study GWs in the ionosphere, as

  2. Ionospheric duct parameters from a dual-payload radio-frequency sounder

    NASA Astrophysics Data System (ADS)

    James, H. G.

    2000-09-01

    Observed characteristics of extraordinary (X) mode reflection pulses in the Observations of Electric-field Distributions in the Ionospheric Plasma-A Unique Strategy C (OEDIPUS-C) topside sounding ionograms have been analyzed to yield the parameters of depletion irregularities that trap and guide (duct) high-frequency waves. The amplitude of successive ionospheric reflection pulses fluctuates by 10 dB or more during frequency sweeps with 50 kHz steps. The pulse period is 3 ms. At the fixed frequency of 4.5 MHz the reflected amplitudes fluctuate much more slowly. The direct pulse from the OEDIPUS-C transmitter to the receiver, consisting of an interference signal between the ordinary and extraordinary modes, is very sensitive to local density changes but shows fluctuations of 10 dB over even longer timescales of ˜1 s. An analysis based on the radiation properties of the transmitter dipoles and on ray optics in cylindrical field-aligned density depletion ducts shows that very shallow depletions of <1% of the ambient density can explain the magnitudes and fluctuations observed in the reflected pulses. Duct density models with steep isodensity contours produce more realistic predictions of signal levels and their fluctuations with frequency than models with gently sloping contours.

  3. HIRS-AMTS satellite sounding system test - Theoretical and empirical vertical resolving power. [High resolution Infrared Radiation Sounder - Advanced Moisture and Temperature Sounder

    NASA Technical Reports Server (NTRS)

    Thompson, O. E.

    1982-01-01

    The present investigation is concerned with the vertical resolving power of satellite-borne temperature sounding instruments. Information is presented on the capabilities of the High Resolution Infrared Radiation Sounder (HIRS) and a proposed sounding instrument called the Advanced Moisture and Temperature Sounder (AMTS). Two quite different methods for assessing the vertical resolving power of satellite sounders are discussed. The first is the theoretical method of Conrath (1972) which was patterned after the work of Backus and Gilbert (1968) The Backus-Gilbert-Conrath (BGC) approach includes a formalism for deriving a retrieval algorithm for optimizing the vertical resolving power. However, a retrieval algorithm constructed in the BGC optimal fashion is not necessarily optimal as far as actual temperature retrievals are concerned. Thus, an independent criterion for vertical resolving power is discussed. The criterion is based on actual retrievals of signal structure in the temperature field.

  4. Recent Advances in Ionospheric Anomalies detection

    NASA Astrophysics Data System (ADS)

    Titov, Anton; Vyacheslav, Khattatov

    2016-07-01

    The variability of the parameters of the ionosphere and ionospheric anomalies are the subject of intensive research. It is widely known and studied in the literature ionospheric disturbances caused by solar activity, the passage of the terminator, artificial heating of high-latitude ionosphere, as well as seismic events. Each of the above types of anomalies is the subject of study and analysis. Analysis of these anomalies will provide an opportunity to improve our understanding of the mechanisms of ionospheric disturbances. To solve this problem are encouraged to develop a method of modeling the ionosphere, based on the assimilation of large amounts of observational data.

  5. A New Inversion Routine to Produce Vertical Electron-Density Profiles from Ionospheric Topside-Sounder Data

    NASA Technical Reports Server (NTRS)

    Wang, Yongli; Benson, Robert F.

    2011-01-01

    Two software applications have been produced specifically for the analysis of some million digital topside ionograms produced by a recent analog-to-digital conversion effort of selected analog telemetry tapes from the Alouette-2, ISIS-1 and ISIS-2 satellites. One, TOPIST (TOPside Ionogram Scalar with True-height algorithm) from the University of Massachusetts Lowell, is designed for the automatic identification of the topside-ionogram ionospheric-reflection traces and their inversion into vertical electron-density profiles Ne(h). TOPIST also has the capability of manual intervention. The other application, from the Goddard Space Flight Center based on the FORTRAN code of John E. Jackson from the 1960s, is designed as an IDL-based interactive program for the scaling of selected digital topside-sounder ionograms. The Jackson code has also been modified, with some effort, so as to run on modern computers. This modification was motivated by the need to scale selected ionograms from the millions of Alouette/ISIS topside-sounder ionograms that only exist on 35-mm film. During this modification, it became evident that it would be more efficient to design a new code, based on the capabilities of present-day computers, than to continue to modify the old code. Such a new code has been produced and here we will describe its capabilities and compare Ne(h) profiles produced from it with those produced by the Jackson code. The concept of the new code is to assume an initial Ne(h) and derive a final Ne(h) through an iteration process that makes the resulting apparent-height profile fir the scaled values within a certain error range. The new code can be used on the X-, O-, and Z-mode traces. It does not assume any predefined profile shape between two contiguous points, like the exponential rule used in Jackson s program. Instead, Monotone Piecewise Cubic Interpolation is applied in the global profile to keep the monotone nature of the profile, which also ensures better smoothness

  6. The Advanced Technology Microwave Sounder (ATMS): The First 10 Months On-Orbit

    NASA Technical Reports Server (NTRS)

    Kim, Edward; Lyu, C-H Joseph; Blackwell, Willaim; Leslie, R. Vince; Baker, Neal; Mo, Tsan; Sun, Ninghai; Bi, Li; Anderson, Kent; Landrum, Mike; DeAmici, Giovanni; Gu, Degui; Foo, Alex; Ibrahim, Wael; Robinson, Kris; Chidester, Lynn; Shiue, James

    2012-01-01

    The Advanced Technology Microwave Sounder (ATMS) is a new satellite microwave sounding sensor designed to provide operational weather agencies with atmospheric temperature and moisture profile information for global weather forecasting and climate applications. A TMS will continue the microwave sounding capabilities first provided by its predecessors, the Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU). The first ATMS was launched October 28, 2011 on board the NPOESS Preparatory Project (NPP) satellite. Microwave soundings by themselves are the highest-impact input data used by Numerical Weather Prediction (NWP) models, especially under cloudy sky conditions. ATMS has 22 channels spanning 23-183 GHz, closely following the channel set of the MSU, AMSU-A1/2, AMSU-B, Microwave Humidity Sounder (MHS), and Humidity Sounder for Brazil (HSB). All this is accomplished with approximately 1/4 the volume, 1/2 the mass, and 1/2 the power of the three AMSUs. A description of ATMS cal/val activities will be presented followed by examples of its performance after its first 10 months on orbit.

  7. Development of the Advanced Technology Microwave Sounder (ATMS) for NPOESS C1

    NASA Astrophysics Data System (ADS)

    Brann, C.; Kunkee, D.

    2008-12-01

    The National Polar-orbiting Operational Environmental Satellite System's Advanced Technology Microwave Sounder (ATMS) is planned for flight on the first NPOESS mission (C1) in 2013. The C1 ATMS will be the second instrument of the ATMS series and will provide along with the companion Cross-track Infrared Sounder (CrIS), atmospheric temperature and moisture profiles for NPOESS. The first flight of the ATMS is scheduled in 2010 on the NPOESS Preparatory Project (NPP) satellite, which is an early instrument risk reduction component of the NPOESS mission. This poster will focus on the development of the ATMS for C1 including aspects of the sensor calibration, antenna beam and RF characteristics and scanning. New design aspects of the C1 ATMS, required primarily by parts obsolescence, will also be addressed in this poster.

  8. Ionospheric physics

    SciTech Connect

    Sojka, J.J. )

    1991-01-01

    Advances in all areas of ionospheric research are reviewed for the 1987-1990 time period. Consideration is given to the equatorial ionosphere, the midlatitude ionosphere and plasmasphere, the auroral ionosphere, the polar ionosphere and polar wind, ionospheric electrodynamic inputs, plasma waves and irregularities, active experiments, ionospheric forecasting, and coupling the ionosphere with other regions.

  9. Vensis: Venus Advanced Radar For Subsurface And Ionosphere Sounding

    NASA Astrophysics Data System (ADS)

    Biccari, D.; Gurnett, D.; Jordan, R.; Huff, R.; Marinangeli, L.; Nielsen, E.; Ori, G. G.; Picardi, G.; Plaut, J.; Provvedi, F.; Seu, R.; Zampolini, E.

    Due to optically opaque atmosphere of Venus radar is the best way to observe the surface of the planet from orbit. Magellan has obtained global SAR imaging, as well as altimetry and emissivity. As a subsurface sounder, working at low frequency and preferably in the night time, VENSIS would obtain fundamentally different kinds of geologic information than Magellan, mapping of interfaces of geologic units (e.g. tessera, plains, lava flows, impact debris) could in fact be extended into the third di- mension. A subsurface investigation of the first 1-2 Km will show the internal defor- mations of the Venusian surface and will depict the structural styles of old crust which are essential to define the crust dynamics, an improved understanding of the evolu- tion of complex Venusian features is a key to define the geological evolution of the planet. Furthermore in standard subsurface sounding mode VENSIS will be able to transmit four different bandwidth, so the possibility of multi frequency observations will allow the estimate of the material attenuation in the crust and will give significant indications on the dielectric properties of the detected interfaces. Thus the Primary Scientific Objectives of VENSIS are the following: 1-Characterize surface roughness, composition and electrical properties at long wavelengths (orders of magnitude longer than Magellan) 2-Probe the subsurface of Venus (to few km depth) to detect and map geologic materials and large scale structures at planetary level VENSIS sounder, using active sounding in a frequency range of 100 kHz to 7 MHz, would also allow detailed characterization of the Venus ionosphere while in passive mode it can be used to detect lightning, the presence of which remains both controversial and critical to understand the behavior of the atmosphere and the possibility of present day volcanism. Therefore a secondary objective is to Probe the ionosphere to characterize interactions between the solar wind and the Venusian

  10. The Advanced Technology Microwave Sounder (ATMS): First Year On-Orbit

    NASA Technical Reports Server (NTRS)

    Kim, Edward J.

    2012-01-01

    The Advanced Technology Microwave Sounder (ATMS) is a new satellite microwave sounding sensor designed to provide operational weather agencies with atmospheric temperature and moisture profile information for global weather forecasting and climate applications. A TMS will continue the microwave sounding capabilities first provided by its predecessors, the Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU). The first flight unit was launched a year ago in October, 2011 aboard the Suomi-National Polar-Orbiting Partnership (S-NPP) satellite, part of the new Joint Polar-Orbiting Satellite System (JPSS). Microwave soundings by themselves are the highest-impact input data used by Numerical Weather Prediction models; and A TMS, when combined with the Cross-track Infrared Sounder (CrIS), forms the Cross-track Infrared and Microwave Sounding Suite (CrIMSS). The microwave soundings help meet sounding requirements under cloudy sky conditions and provide key profile information near the surface. ATMS was designed & built by Aerojet Corporation in Azusa, California, (now Northrop Grumman Electronic Systems). It has 22 channels spanning 23-183 GHz, closely following the channel set of the MSU, AMSU-AI/2, AMSU-B, Microwave Humidity Sounder (MHS), and Humidity Sounder for Brazil (HSB). It continues their cross-track scanning geometry, but for the first time, provides Nyquist sample spacing. All this is accomplished with approximately V. the volume, Y, the mass, and Y, the power of the three AMSUs. A description will be given of its performance from its first year of operation as determined by post-launch calibration activities. These activities include radiometric calibration using the on-board warm targets and cold space views, and geolocation determination. Example imagery and zooms of specific weather events will be shown. The second ATMS flight model is currently under construction and planned for launch on the "Jl" satellite of the JPSS program in

  11. Advanced sounder validation studies from recent NAST-I airborne field campaigns

    NASA Astrophysics Data System (ADS)

    Larar, Allen M.; Zhou, Daniel K.; Liu, Xu; Tian, Jialin; Smith, William L.

    2016-05-01

    The evolution of satellite measurement systems continues to improve their research and operational impact and is essential for advancing global observations of the Earth's atmosphere, clouds, and surface. Measurement system and data product validation is required to fully exploit these data for enabling their intended enhancements in weather prediction, climate monitoring capability, and environmental change detection. Airborne field campaigns can play a vital role in such validation and contribute to assessing and improving satellite sensor measurements and associated data products. The NASA LaRC National Airborne Sounder Testbed - Interferometer (NAST-I) was part of the aircraft payload for the two field experiments conducted to address Suomi NPP (SNPP) validation since the satellite's launch in late 2011: 1) mid-latitude flights based out of Palmdale, CA during May 2013 (SNPP-1), and 2) flights over Greenland during March 2015 while based out of Keflavik, Iceland (SNPP-2). This presentation focuses on radiance analysis from the SNPP airborne field campaigns with a particular emphasis on NAST-I inter-comparisons with the Cross-track Infrared Sounder (CrIS) for challenging cold scene conditions as observed during SNPP-2.

  12. Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) after nine years of operation: A summary

    NASA Astrophysics Data System (ADS)

    Orosei, R.; Jordan, R. L.; Morgan, D. D.; Cartacci, M.; Cicchetti, A.; Duru, F.; Gurnett, D. A.; Heggy, E.; Kirchner, D. L.; Noschese, R.; Kofman, W.; Masdea, A.; Plaut, J. J.; Seu, R.; Watters, T. R.; Picardi, G.

    2015-07-01

    Mars Express, the first European interplanetary mission, carries the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) to search for ice and water in the Martian subsurface. Developed by an Italian-US team, MARSIS transmits low-frequency, wide-band radio pulses penetrating below the surface and reflected by dielectric discontinuities linked to structural or compositional changes. MARSIS is also a topside ionosphere sounder, transmitting a burst of short, narrow-band pulses at different frequencies that are reflected by plasma with varying densities at different altitudes. The radar operates since July 2005, after the successful deployment of its 40 m antenna, acquiring data at altitudes lower than 1200 km. Subsurface sounding (SS) data are processed on board by stacking together a batch of echoes acquired at the same frequency. On ground, SS data are further processed by correlating the received echo with the transmitted waveform and compensating de-focusing caused by the dispersive ionosphere. Ground processing of active ionospheric sounding (AIS) data consists in the reconstruction of the electron density profile as a function of altitude. MARSIS observed the internal structure of Planum Boreum outlining the Basal Unit, an icy deposit lying beneath the North Polar Layered Deposits thought to have formed in an epoch in which climate was markedly different from the current one. The total volume of ice in polar layered deposits could be estimated, and parts of the Southern residual ice cap were revealed to consist of ≈ 10 m of CO2 ice. Radar properties of the Vastitas Borealis Formation point to the presence of large quantities of ice buried beneath the surface. Observations of the ionosphere revealed the complex interplay between plasma, crustal magnetic field and solar wind, contributing to space weather studies at Mars. The presence of three-dimensional plasma structures in the ionosphere was revealed for the first time. MARSIS could

  13. The Advanced Technology Microwave Sounder (ATMS): A New Operational Sensor Series

    NASA Technical Reports Server (NTRS)

    Kim, Edward; Lyu, Cheng-H Joseph; Leslie, R. Vince; Baker, Neal; Mo, Tsan; Sun, Ninghai; Bi, Li; Anderson, Mike; Landrum, Mike; DeAmici, Giovanni; Gu, Degui; Foo, Alex; Ibrahim, Wael; Robinson, Kris; Chidester, Lynn; Shiue, James

    2012-01-01

    ATMS is a new satellite microwave sounding sensor designed to provide operational weather agencies with atmospheric temperature and moisture profile information for global weather forecasting and climate applications. ATMS will continue the microwave sounding capabilities first provided by its predecessors, the Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU). The first ATMS was launched October 28, 2011 on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite. Microwave soundings by themselves are the highest-impact input data used by Numerical Weather Prediction (NWP) models; and ATMS, when combined with the Cross-track Infrared Sounder (CrIS), forms the Cross-track Infrared and Microwave Sounding Suite (CrIMSS). The microwave soundings help meet NWP sounding requirements under cloudy sky conditions and provide key profile information near the surface

  14. Hurricane Sandy warm-core structure observed from advanced Technology Microwave Sounder

    NASA Astrophysics Data System (ADS)

    Zhu, Tong; Weng, Fuzhong

    2013-06-01

    The warm-core structures of Hurricane Sandy and other nine tropical cyclones (TCs) are studied using the temperatures retrieved from Advanced Technology Microwave Sounder (ATMS). A new algorithm is developed for the retrieval of atmospheric temperature profiles from the ATMS radiances. Since ATMS observation has a higher spatial resolution and better coverage than its predecessor, Advanced Microwave Sounding Unit-A, the retrieved temperature field explicitly resolves TC warm core throughout troposphere and depicts the cold temperature anomalies in the eyewall and spiral rainbands. Unlike a typical TC, the height of maximum warm core of Hurricane Sandy is very low, but the storm size is quite large. Based on the analysis of 10 TCs in 2012, close correlations are found between ATMS-derived warm core and the TC maximum sustained wind (MSW) or minimum sea level pressure (MSLP). The estimation errors of MSW and MSLP from ATMS-retrieved warm core are 13.5 mph and 13.1 hPa, respectively.

  15. Characterization of geolocation accuracy of Suomi NPP Advanced Technology Microwave Sounder measurements

    NASA Astrophysics Data System (ADS)

    Han, Yang; Weng, Fuzhong; Zou, Xiaolei; Yang, Hu; Scott, Deron

    2016-05-01

    The Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership satellite has 22 channels at frequencies ranging from 23 to 183 GHz for probing the atmospheric temperature and moisture under all weather conditions. As part of the ATMS calibration and validation activities, the geolocation accuracy of ATMS data must be well characterized and documented. In this study, the coastline crossing method (CCM) and the land-sea fraction method (LFM) are utilized to characterize and quantify the ATMS geolocation accuracy. The CCM is based on the inflection points of the ATMS window channel measurements across the coastlines, whereas the LFM collocates the ATMS window channel data with high-resolution land-sea mask data sets. Since the ATMS measurements provide five pairs of latitude and longitude data for K, Ka, V, W, and G bands, respectively, the window channels 1, 2, 3, 16, and 17 from each of these five bands are chosen for assessing the overall geolocation accuracy. ATMS geolocation errors estimated from both methods are generally consistent from 40 cases in June 2014. The ATMS along-track (cross-track) errors at nadir are within ±4.2 km (±1.2 km) for K/Ka, ±2.6 km (±2.7 km) for V bands, and ±1.2 km (±0.6 km) at W and G bands, respectively. At the W band, the geolocation errors derived from both algorithms are probably less reliable due to a reduced contrast of brightness temperatures in coastal areas. These estimated ATMS along-track and cross-track geolocation errors are well within the uncertainty requirements for all bands.

  16. Biases in Total Precipitable Water Vapor Climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Eldering, Annmarie; Aumann, Hartmut H.; Chahine, Moustafa T.

    2006-01-01

    We examine differences in total precipitable water vapor (PWV) from the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Scanning Radiometer (AMSR-E) experiments sharing the Aqua spacecraft platform. Both systems provide estimates of PWV over water surfaces. We compare AIRS and AMSR-E PWV to constrain AIRS retrieval uncertainties as functions of AIRS retrieved infrared cloud fraction. PWV differences between the two instruments vary only weakly with infrared cloud fraction up to about 70%. Maps of AIRS-AMSR-E PWV differences vary with location and season. Observational biases, when both instruments observe identical scenes, are generally less than 5%. Exceptions are in cold air outbreaks where AIRS is biased moist by 10-20% or 10-60% (depending on retrieval processing) and at high latitudes in winter where AIRS is dry by 5-10%. Sampling biases, from different sampling characteristics of AIRS and AMSR-E, vary in sign and magnitude. AIRS sampling is dry by up to 30% in most high-latitude regions but moist by 5-15% in subtropical stratus cloud belts. Over the northwest Pacific, AIRS samples conditions more moist than AMSR-E by a much as 60%. We hypothesize that both wet and dry sampling biases are due to the effects of clouds on the AIRS retrieval methodology. The sign and magnitude of these biases depend upon the types of cloud present and on the relationship between clouds and PWV. These results for PWV imply that climatologies of height-resolved water vapor from AIRS must take into consideration local meteorological processes affecting AIRS sampling.

  17. Stimulated plasma instability and nonlinear phenomena in the ionosphere

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1982-01-01

    Several hundred topside ionograms were used to study simulated wave-particle interactions in the ionosphere. The study combined the benefits of high-frequency-resolution Alouette 2 analog sounder data with advanced digital graphics techniques. The study shows that the sounder phase can cause significant plasma heating when the plasma parameter is confined to specific ranges. The observations support the Harris instability generation process and the nonlinear Landau damping maintaining process for long-duration diffuse resonances. The observations also suggest that the so-called Q resonances have characteristics which imply that generation processes in a sounder-stimulated plasma turbulence may be involved.

  18. Requirements for an Advanced Low Earth Orbit (LEO) Sounder (ALS) for Improved Regional Weather Prediction and Monitoring of Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Chahine, Moustafa T.; Susskind, Joel

    2008-01-01

    Hyperspectral infrared atmospheric sounders (e.g., the Atmospheric Infrared Sounder (AIRS) on Aqua and the Infrared Atmospheric Sounding Interferometer (IASI) on Met Op) provide highly accurate temperature and water vapor profiles in the lower to upper troposphere. These systems are vital operational components of our National Weather Prediction system and the AIRS has demonstrated over 6 hrs of forecast improvement on the 5 day operational forecast. Despite the success in the mid troposphere to lower stratosphere, a reduction in sensitivity and accuracy has been seen in these systems in the boundary layer over land. In this paper we demonstrate the potential improvement associated with higher spatial resolution (1 km vs currently 13.5 km) on the accuracy of boundary layer products with an added consequence of higher yield of cloud free scenes. This latter feature is related to the number of samples that can be assimilated and has also shown to have a significant impact on improving forecast accuracy. We also present a set of frequencies and resolutions that will improve vertical resolution of temperature and water vapor and trace gas species throughout the atmosphere. Development of an Advanced Low Earth Orbit (LEO) Sounder (ALS) with these improvements will improve weather forecast at the regional scale and of tropical storms and hurricanes. Improvements are also expected in the accuracy of the water vapor and cloud properties products, enhancing process studies and providing a better match to the resolution of future climate models. The improvements of technology required for the ALS are consistent with the current state of technology as demonstrated in NASA Instrument Incubator Program and NOAA's Hyperspectral Environmental Suite (HES) formulation phase development programs.

  19. Advanced Ionospheric Sensing using GROUP-C and LITES aboard the ISS

    NASA Astrophysics Data System (ADS)

    Budzien, S. A.; Stephan, A. W.; Chakrabarti, S.; Finn, S. C.; Cook, T.; Powell, S. P.; O'Hanlon, B.; Bishop, R. L.

    2015-12-01

    The GPS Radio Occultation and Ultraviolet Photometer Co-located (GROUP-C) and Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) experiments are manifested for flight aboard the International Space Station (ISS) in 2016 as part of the Space Test Program Houston #5 payload. The two experiments provide technical development and risk-reduction for future DoD space weather sensors suitable for ionospheric specification, space situational awareness, and data products for global ionosphere assimilative models. In addition, the combined instrument complement of these two experiments offers a unique opportunity to study structures of the nighttime ionosphere. GROUP-C includes an advanced GPS receiver providing ionospheric electron density profiles and scintillation measurements and a high-sensitivity far-ultraviolet photometer measuring horizontal ionospheric gradients. LITES is an imaging spectrograph that spans 60-140 nm and will obtain high-cadence limb profiles of the ionosphere and thermosphere from 150-350 km altitude. In the nighttime ionosphere, recombination of O+ and electrons produces optically thin emissions at 91.1 and 135.6 nm that can be used to tomographically reconstruct the two-dimensional plasma distribution in the orbital plane below ISS altitudes. Ionospheric irregularities, such as plasma bubbles and blobs, are transient features of the low and middle latitude ionosphere with important implications for operational systems. Irregularity structures have been studied primarily using ground-based systems, though some spaced-based remote and in-situ sensing has been performed. An ionospheric observatory aboard the ISS would provide new capability to study low- and mid-latitude ionospheric structures on a global scale. By combining for the first time high-sensitivity in-track photometry, vertical ionospheric airglow spectrographic imagery, and recent advancements in UV tomography, high-fidelity tomographic reconstruction of

  20. Advances in remote sensing of the daytime ionosphere with EUV airglow

    NASA Astrophysics Data System (ADS)

    Stephan, Andrew W.

    2016-09-01

    This paper summarizes recent progress in developing a method for characterizing the daytime ionosphere from limb profile measurements of the OII 83.4 nm emission. This extreme ultraviolet emission is created by solar photoionization of atomic oxygen in the lower thermosphere and is resonantly scattered by O+ in the ionosphere. The brightness and shape of the measured altitude profile thus depend on both the photoionization source in the lower thermosphere and the ionospheric densities that determine the resonant scattering contribution. This technique has greatly matured over the past decade due to measurements by the series of Naval Research Laboratory Special Sensor Ultraviolet Limb Imager (SSULI) instruments flown on Defense Meteorological Satellite Program (DMSP) missions and the Remote Atmospheric and Ionospheric Detection System (RAIDS) on the International Space Station. The volume of data from these missions has enabled a better approach to handling specific biases and uncertainties in both the measurement and retrieval process that affect the accuracy of the result. This paper identifies the key measurement and data quality factors that will enable the continued evolution of this technique into an advanced method for characterization of the daytime ionosphere.

  1. Recent advances in real-time analysis of ionograms and ionospheric drift measurements with digisondes

    NASA Astrophysics Data System (ADS)

    Reinisch, B. W.; Huang, X.; Galkin, I. A.; Paznukhov, V.; Kozlov, A.

    2005-08-01

    Reliable long distance RF communication and transionospheric radio links depend critically on space weather, and specifically ionospheric conditions. Modern ground-based ionosondes provide space weather parameters in real-time including the vertical electron density distribution up to ˜1000 km and the velocity components of the ionospheric F region drift. A global network of digisondes distributes this information in real-time via internet connections. The quality of the automatic scaling of the echo traces in ionograms was a continuous concern ever since first attempts have been reported. The modern low-power ionosonde with ˜100 W transmitters (compared to several kilowatt for the older ionosondes) relies on more sophisticated signal processing to enhance the signal-to-noise ratio and to retrieve the essential ionospheric characteristics. Recent advances in the automatic scaling algorithm ARTIST have significantly increased the reliability of the autoscaled data, making the data, in combination with models, more useful for ionospheric now-casting. Vertical and horizontal F region drift velocities are a new real-time output of the digisondes. The “ionosonde drift” is derived from the measured Doppler frequency shift and angle of arrival of ionospherically reflected HF echoes, a method similar to that used by coherent VHF and incoherent scatter radars.

  2. Lessons Learned from Previous Space-Borne Sounders as a Guide to Future Sounder Development

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Deshpande, Manohar D.; Farrell,William M.; Fung, Shing F.; Osherovich, Vladimir A.; Pfaff, Rovert E.; Rowland, Douglas E.; Adrian, Mark L.

    2008-01-01

    Space-borne radio sounding is considered to be the gold standard for electron-density (N(sub e)) measurements compared to other techniques even under low-density conditions, such as N(sub e) < 1/cu cm, when other techniques are known to experience difficulties. These reliable measurements are not restricted to in-situ N(sub e) determinations since a spaceborne sounder can provide vertical N(sub e) profiles (N(sub e)(h)) from the spacecraft altitude to the altitude of maximum N(sub e). Near-conjunction studies involving the International Satellites for Ionospheric Studies (ISIS) satellites in the topside ionosphere and Dynamics Explorer 2 (DE 2) near the altitude of the F-region peak density have verified that, even at the greatest distance from the sounder, the ISIS-derived N(sub e)(h) profiles agree with the DE-2 Langmuir-probe measurements to within about 30% over a density range of more than two decades. Space-borne sounders can also provide N(sub e) profiles along the magnetic-field B, by inverting echoes that are ducted along field-aligned irregularities (FAI), and can provide information about the terrain beneath the satellite by examining surface reflections in the frequency range above the ionospheric penetration frequency. Many nations have launched rocket and satellite radio sounders in geospace over more than 4 decades and there have been sounders on space-probes and in orbit around other planets. Here we will summarize some of the lessons learned from these accomplishments by analyzing data from radio sounders on the Alouette and ISIS satellites and the OEDIPUS and other rockets in the terrestrial ionosphere, the IMAGE satellite in the terrestrial magnetosphere, the Ulysses space probe in Jupiter's 10 plasma torus and the MARSIS satellite in orbit around Mars. The emphasis will be on information deduced concerning (1) fundamental plasma processes and gradients in N, and B in the vicinity of the sounders from sounder-stimulated plasma resonances and

  3. Advancing spaceborne tools for the characterization of planetary ionospheres and circumstellar environments

    NASA Astrophysics Data System (ADS)

    Douglas, Ewan Streets

    This work explores remote sensing of planetary atmospheres and their circumstellar surroundings. The terrestrial ionosphere is a highly variable space plasma embedded in the thermosphere. Generated by solar radiation and predominantly composed of oxygen ions at high altitudes, the ionosphere is dynamically and chemically coupled to the neutral atmosphere. Variations in ionospheric plasma density impact radio astronomy and communications. Inverting observations of 83.4 nm photons resonantly scattered by singly ionized oxygen holds promise for remotely sensing the ionospheric plasma density. This hypothesis was tested by comparing 83.4 nm limb profiles recorded by the Remote Atmospheric and Ionospheric Detection System aboard the International Space Station to a forward model driven by coincident plasma densities measured independently via ground-based incoherent scatter radar. A comparison study of two separate radar overflights with different limb profile morphologies found agreement between the forward model and measured limb profiles. A new implementation of Chapman parameter retrieval via Markov chain Monte Carlo techniques quantifies the precision of the plasma densities inferred from 83.4 nm emission profiles. This first study demonstrates the utility of 83.4 nm emission for ionospheric remote sensing. Future visible and ultraviolet spectroscopy will characterize the composition of exoplanet atmospheres; therefore, the second study advances technologies for the direct imaging and spectroscopy of exoplanets. Such spectroscopy requires the development of new technologies to separate relatively dim exoplanet light from parent star light. High-contrast observations at short wavelengths require spaceborne telescopes to circumvent atmospheric aberrations. The Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) team designed a suborbital sounding rocket payload to demonstrate visible light high-contrast imaging with a visible nulling coronagraph

  4. Spaceborne Infrared Atmospheric Sounder

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas; Macenka, Steven; Kampe, Thomas

    2004-01-01

    A report describes the development of the spaceborne infrared atmospheric sounder (SIRAS) - a spectral imaging instrument, suitable for observing the atmosphere of the Earth from a spacecraft, that utilizes four spectrometers to cover the wavelength range of 12 to 15.4 m with a spectral resolution that ranges between 1 part per 900 and 1 part per 1,200 in wavelength. The spectrometers are operated in low orders to minimize filtering requirements. Focal planes receive the dispersed energy and provide a spectrum of the scene. The design of the SIRAS combines advanced, wide-field refractive optics with high-dispersion gratings in a solid-state (no moving parts), diffraction-limited optical system that is the smallest such system that can be constructed for the specified wavelength range and resolution. The primary structure of the SIRAS has dimensions of 10 by 10 by 14 cm and has a mass of only 2.03 kg

  5. Pre-Launch Characterization of the Advanced Technology Microwave Sounder (ATMS) on the Joint Polar Satellite System-1 Satellite (JPSS-1)

    NASA Astrophysics Data System (ADS)

    Kim, Edward; Leslie, Vince; Lyu, Joseph; Smith, Craig; McCormick, Lisa; Anderson, Kent

    2016-04-01

    The Advanced Technology Microwave Sounder (ATMS) is the newest generation of microwave sounder in the international fleet of polar-orbiting weather satellites, replacing the Advanced Microwave Sounding Unit (AMSU) which first entered service in 1998. The first ATMS was launched aboard the Suomi NPP (S-NPP) satellite in late 2011. The second ATMS is manifested on the Joint Polar Satellite System-1 Satellite (JPSS-1). ATMS provides 22 channels of temperature and humidity sounding observations over a frequency range from 23 to 183 GHz. These microwave soundings provide the highest impact data ingested by operational Numerical Weather Prediction (NWP) models, and are the most critical of the polar-orbiting satellite observations, particularly because microwave sensing can penetrate clouds. This paper will present performance characterizations from pre-launch calibration measurements of the JPSS-1 ATMS just completed in December, 2015. The measurements were conducted in a thermal vacuum chamber with blackbody targets simulating cold space, ambient, and a variable Earth scene. They represent the best opportunity for calibration characterization of the instrument since the environment can be carefully controlled. We will present characterizations of the sensitivity (NEDT), accuracy, nonlinearity, noise spectral characteristics, gain stability, repeatability, and inter-channel correlation. An estimate of expected "striping" will be presented, and a discussion of reflector emissivity effects will also be provided. Comparisons will be made with the S-NPP flight unit. Finally, we will describe planned on-orbit characterizations - such as pitch and roll maneuvers - that will further improve both the measurement quality and the understanding of various error contributions.

  6. Ionospheric topside sounding.

    PubMed

    Calvert, W

    1966-10-14

    Over the past few years, the satellite topside sounders have significantly contributed to the understanding of the upper ionosphere. A great quantity of radio echo data has been accumulated, from which the ionospheric electrondensity distribution can be determined. The topside measurements of electron density essentially agree with similar measurements from the ground, except for an occasional 10-percent discrepancy near the peak of the ionosphere. While horizontal non-uniformity is a likely cause, this discrepancy has not yet been adequately explained. The electron-density scale heights measured at a constant altitude indicate both a higher temperature and a heavier mean ion mass at high latitudes. At low latitudes the topside measurements have shown the detailed latitudinal structure of the equatorial anomaly, demonstrating control by the geomagnetic field. A variety of electron-density irregularities have been studied. Most are greatly elongated along the magnetic field, and produce echoes either by lateral scattering, if they are thin, or by longitudinal ducting, if they are thick. Some of the thick irregularities are continuous between the hemispheres and support conjugate echo propagation. The topside sounders have revealed the complex structure of the ionosphere near the auroral zone and at higher latitudes. At night an east-west trough of greatly reduced electron density occurs equatorward of the auroral zone. At the auroral zone itself the electron density is high and quite variable, both in space and time. The electron density at the polar cap within the auroral zone is often uniform and smooth. Ionospheric irregularities are common in the area of the trough and the auroral zone. Among other satellites, the topside sounders have been used in various plasma studies involving the excitation and propagation of waves. These studies suggest that the ionosphere is an appropriate region for future plasma physics investigations, especially with rocket and

  7. Radiation budget studies using collocated observations from advanced Very High Resolution Radiometer, High-Resolution Infrared Sounder/2, and Earth Radiation Budget Experiment instruments

    NASA Technical Reports Server (NTRS)

    Ackerman, Steven A.; Frey, Richard A.; Smith, William L.

    1992-01-01

    Collocated observations from the Advanced Very High Resolution Radiometer (AVHRR), High-Resolution Infrared Sounder/2 (HIRS/2), and Earth Radiation Budget Experiment (ERBE) instruments onboard the NOAA 9 satellite are combined to describe the broadband and spectral radiative properties of the earth-atmosphere system. Broadband radiative properties are determined from the ERBE observations, while spectral properties are determined from the HIRS/2 and AVHRR observations. The presence of clouds, their areal coverage, and cloud top pressure are determined from a combination of the HIRS/2 and the AVHRR observations. The CO2 slicing method is applied to the HIRS/2 to determine the presence of upper level clouds and their effective emissivity. The AVHRR data collocated within the HIRS/2 field of view are utilized to determine the uniformity of the scene and retrieve sea surface temperature. Changes in the top of the atmosphere longwave and shortwave radiative energy budgets, and the spectral distribution of longwave radiation are presented as a function of cloud amount and cloud top pressure. The radiative characteristics of clear sky conditions over oceans are presented as a function of sea surface temperature and atmospheric water vapor structure.

  8. Atmospheric infrared sounder

    NASA Technical Reports Server (NTRS)

    Rosenkranz, Philip, W.; Staelin, David, H.

    1995-01-01

    This report summarizes the activities of two Atmospheric Infrared Sounder (AIRS) team members during the first half of 1995. Changes to the microwave first-guess algorithm have separated processing of Advanced Microwave Sounding Unit A (AMSU-A) from AMSU-B data so that the different spatial resolutions of the two instruments may eventually be considered. Two-layer cloud simulation data was processed with this algorithm. The retrieved water vapor column densities and liquid water are compared. The information content of AIRS data was applied to AMSU temperature profile retrievals in clear and cloudy atmospheres. The significance of this study for AIRS/AMSU processing lies in the improvement attributable to spatial averaging and in the good results obtained with a very simple algorithm when all of the channels are used. Uncertainty about the availability of either a Microwave Humidity Sensor (MHS) or AMSU-B for EOS has motivated consideration of possible low-cost alternative designs for a microwave humidity sensor. One possible configuration would have two local oscillators (compared to three for MHS) at 118.75 and 183.31 GHz. Retrieval performances of the two instruments were compared in a memorandum titled 'Comparative Analysis of Alternative MHS Configurations', which is attached.

  9. Oblique reflections in the Mars Express MARSIS data set: Stable density structures in the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Andrews, David; André, Mats; Opgenoorth, Hermann; Edberg, Niklas; Diéval, Catherine; Duru, Firdevs; Gurnett, Donald; Morgan, David; Witasse, Olivier

    2014-05-01

    The Mars Advanced Radar for Sub-surface and Ionospheric Sounding (MARSIS) on board ESA's Mars Express (MEX) spacecraft routinely detects evidence of horizontal plasma density structures in the Martian ionosphere. Such structures, likely taking the form of spatially-extended elevations in the plasma density at a given altitude, give rise to oblique reflections in the Active Ionospheric Sounder (AIS) data. These structures are likely related to the highly-varied Martian crustal magnetic field. In this study, we use the polar orbit of MEX to investigate the repeatability of the ionospheric structures producing these anomalous reflections, examining sequences of multiple orbits which pass over the same regions of the Martian surface under similar solar illuminations. Presenting three such examples, or case-studies, we show that the signatures of these ionospheric structures are often incredibly stable over periods of many tens of days. To further investigate the nature of these ionospheric structures, we use a 2D ray-tracing code to simulate MARSIS's response to a variety of anomalous ionospheric profiles.

  10. Radiation from sounder-accelerated electrons

    NASA Astrophysics Data System (ADS)

    James, H. G.

    2006-01-01

    Quasi-electrostatic Z-mode waves observed in the two-point OEDIPUS-C (OC) transmission experiment have been interpreted as incoherent radiation by sounder-accelerated electrons (SAE). A consistent interpretation of slow Z-mode waves created by SAE, based on wave and particle observations, has been built around the theory of incoherent radiation. The question therefore arises as to whether some transmitter-induced waves observed by monostatic sounder receivers in the same frequency domain, from the greater of the electron plasma and gyro frequencies to the upper-hybrid-resonance frequency, can also be explained as caused by SAE. Two candidate signal types routinely observed in the ISIS-II sounder receiver have been examined: (a) a diffuse resonance ’spike’ lasting a few milliseconds and (b) highly elongated pulses distributed smoothly throughout the entire frequency range observed when the ambient ionospheric plasma exhibits density irregularities. An examination of Z-mode wave phase and group velocities, combined with consideration of wave and spacecraft kinematics, indicate that the hypothesis of plane slow Z waves does not suffice. The particle detector located on the same payload as the OC transmitter measures SAE pulses lasting milliseconds. Consideration of the role of the transmitter payload body appears to be necessary to account for the retention around the payload of SAE at various pitch angles and energies up to about 100 eV.

  11. The topside sounder database - Data screening and systematic biases

    NASA Astrophysics Data System (ADS)

    Verhulst, Tobias; Stankov, Stanimir M.

    2013-06-01

    The ionospheric topside sounder measurement database developed at the US National Space Science Data Center (NSSDC) is a valuable source of information when investigating the composition and complex dynamics of the upper ionosphere. The database is increasingly used by many scientists around the world for both research and development of empirical models. However, there is always a danger of indiscriminately using the data without properly assessing the data quality and applicability for a given purpose. This paper is concerned with the issue of data screening and pre-processing of the Alouette/ISIS topside sounder database. An overview of the original database availability and formatting is given and the use of solar and geomagnetic indices is discussed. Data screening procedures, concerning detection and handling of erroneous profiles, are also presented. Special attention is drawn to the systematic biases observed in the database and the possibilities for their removal.

  12. AIRS - the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Lambrigsten, Bjorn H.; Fetzer, Eric; Fishbein, Evan; Lee, Sung-Yung; Paganao, Thomas

    2004-01-01

    The Atmospheric Infrared Sounder (AIRS) was launched in 2002, along with two companion microwave sounders. This AIRS sounding suite is the most advanced atmospheric sounding system to date, with measurement accuracies far surpassing those of current weather satellites. From its sun synchronous polar orbit, the AIRS system provides more than 90% of the globe every 24 hours. Much of the post-launch period has been devoted to optimizing the 'retrieval' system used to derive atmospheric and other parameters from the observations and to validate those parameters. The geophysical parameters have been produced since the beginning of 2003 - the first data were released to the public in mid-2003, and future improved versions will be released periodically. The ongoing calibration/validation effort has confirmed that the system is very accurate and stable. There are a number of applications for the AIRS products, ranging from numerical weather prediction - where positive impact on forecast accuracy has already been demonstrated, to atmospheric research - where the AIRS water vapor products near the surface and in the mid and upper troposphere as well as in the stratosphere promise to make it possible to characterize and model phenomena that are key for short-term atmospheric processes, from weather patterns to long-term processes, such as interannual variability and climate change.

  13. Oblique reflections in the Mars Express MARSIS data set: Stable density structures in the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Andrews, D. J.; André, M.; Opgenoorth, H. J.; Edberg, N. J. T.; Diéval, C.; Duru, F.; Gurnett, D. A.; Morgan, D.; Witasse, O.

    2014-05-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the European Space Agency's Mars Express (MEX) spacecraft routinely detects evidence of localized plasma density structures in the Martian dayside ionosphere. Such structures, likely taking the form of spatially extended elevations in the plasma density at a given altitude, give rise to oblique reflections in the Active Ionospheric Sounder data. These structures are likely related to the highly varied Martian crustal magnetic field. In this study we use the polar orbit of MEX to investigate the repeatability of the ionospheric structures producing these anomalous reflections, examining data taken in sequences of multiple orbits which pass over the same regions of the Martian surface under similar solar illuminations, within intervals lasting tens of days. Presenting three such examples, or case studies, we show for the first time that these oblique reflections are often incredibly stable, indicating that the underlying ionospheric structures are reliably reformed in the same locations and with qualitatively similar parameters. The visibility, or lack thereof, of a given oblique reflection on a single orbit can generally be attributed to variations in the crustal field within the ionosphere along the spacecraft trajectory. We show that, within these examples, oblique reflections are generally detected whenever the spacecraft passes over regions of intense near-radial crustal magnetic fields (i.e., with a "cusp-like" configuration). The apparent stability of these structures is an important feature that must be accounted for in models of their origin.

  14. Topside sounder observations of equatorial bubbles

    NASA Technical Reports Server (NTRS)

    Dyson, P. L.; Benson, R. F.

    1978-01-01

    Large scale regions of depleted equatorial ionospheric plasma, called equatorial bubbles, are investigated using topside sounder data. The sounder's unique remote measuring capability enables the magnetic field-aligned nature of the bubbles to be investigated. A search of all available Alouette 2 and ISIS 1 ionograms during nighttime perigee passes near the magnetic equator has revealed a variety of echo signatures associated with bubbles. In addition to a sudden drop in electron density, these signatures usually include in situ spread F and ducted traces. The ducted traces have been used to determine the electron density distribution and to infer changes in ion composition along the magnetic field line within the duct associated with the bubble. In some cases it can be determined that the bubble is asymmetric with respect to the magnetic equator. Even though such features require 3 dimensional models for their explanation, the great field-aligned extent of the bubbles (relative to their cross section) suggests that current theories, which ignore variations along the magnetic field, are still applicable.

  15. Recent Advances in Remote Sensing of Natural Hazards-Induced Atmospheric and Ionospheric Perturbations

    NASA Astrophysics Data System (ADS)

    Yang, Y. M.; Komjathy, A.; Meng, X.; Verkhoglyadova, O. P.; Langley, R. B.; Mannucci, A. J.

    2015-12-01

    Traveling ionospheric disturbances (TIDs) induced by acoustic-gravity waves in the neutral atmosphere have significant impact on trans-ionospheric radio waves such as Global Navigation Satellite System (GNSS, including Global Position System (GPS)) measurements. Natural hazards and solid Earth events, such as earthquakes, tsunamis and volcanic eruptions are actual sources that may trigger acoustic and gravity waves resulting in traveling ionospheric disturbances (TIDs) in the upper atmosphere. Trans-ionospheric radio wave measurements sense the total electron content (TEC) along the signal propagation path. In this research, we introduce a novel GPS-based detection and estimation technique for remote sensing of atmospheric wave-induced TIDs including space weather phenomena induced by major natural hazard events, using TEC time series collected from worldwide ground-based dual-frequency GNSS (including GPS) receiver networks. We demonstrate the ability of using ground- and space-based dual-frequency GPS measurements to detect and monitor tsunami wave propagation from the 2011 Tohoku-Oki earthquake and tsunami. Major wave trains with different propagation speeds and wavelengths were identified through analysis of the GPS remote sensing observations. Dominant physical characteristics of atmospheric wave-induced TIDs are found to be associated with specific tsunami propagations and oceanic Rayleigh waves. In this research, we compared GPS-based observations, corresponding model simulations and tsunami wave propagation. Results are shown to lead to a better understanding of the tsunami-induced ionosphere responses. Based on current distribution of Plate Boundary Observatory GPS stations, the results indicate that tsunami-induced TIDs may be detected about 60 minutes prior to tsunamis arriving at the U.S. west coast. It is expected that this GNSS-based technology will become an integral part of future early-warning systems.

  16. Low Frequency Rada Sounding Through Martian Ionosphere

    NASA Technical Reports Server (NTRS)

    Safaeinili, A.; Jordan, R.

    2000-01-01

    In remote radar sounding, it is highly desirable to operate at low frequencies to improve depth of penetration. For spaceborne sounders, the lowest operating frequency is limited by the effect of the ionosphere due to significant dispersion of the radar waves at near plasma frequency.

  17. Stimulated plasma waves in the ionosphere

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1977-01-01

    The reported discussion is concerned with longitudinal waves associated with electron motions. These waves are easily stimulated in the ionosphere by rocket- and satellite-borne RF sounders. Most of the observations of stimulated plasma waves in the ionosphere are based on ionograms obtained from the sounders carried on board five satellites, including Explorer 20, Alouette 1 and 2, and ISIS 1 and 2. The majority of the observations can be explained by considering the propagation of the sounder-stimulated plasma waves. Attention is given to aspects of plasma wave dispersion, linear phenomena, plasma wave instabilities and nonlinear phenomena, unexplained phenomena, diagnostic applications, geophysical and astrophysical applications, and a number of experiments planned for the future.

  18. Intensity of nightside MARSIS AIS surface reflections and implications for low-altitude ionospheric densities

    NASA Astrophysics Data System (ADS)

    Němec, F.; Morgan, D. D.; Diéval, C.; Gurnett, D. A.

    2015-04-01

    Spacecraft radar sounding signals at frequencies higher than the ionospheric peak plasma frequency are not reflected by the ionosphere. Instead, they make it to the ground where they are reflected by the planetary surface. We analyze the intensity of the surface reflections measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) ionospheric radar sounder on board the Mars Express spacecraft. Apart from the surface reflectivity and the spacecraft altitude, the detected intensity of surface reflections is controlled primarily by the signal attenuation during the ionospheric propagation. We focus on the nightside region, where the ionospheric densities in the main layer are too low to cause a significant attenuation and allow sampling of the surface reflections at frequencies down to 3 MHz. The attenuation occurs mainly at altitudes below 100 km, where the electron-neutral collision frequency is a maximum. The intensity of surface reflections can thus serve as a proxy for electron densities at low altitudes not accessible by the direct ionospheric radar sounding. We analyze the intensity of surface reflections as a function of relevant controlling parameters. The intensity of surface reflections is lower at higher solar zenith angles on the nightside and during the periods of larger solar activity. Moreover, it exhibits a seasonal variation that is related to the dust storm occurrence. The intensity of surface reflections is lower in areas of closed magnetic field lines, suggesting that nightside electron densities behave rather differently at low altitudes than at higher altitudes. This is confirmed by comparison with simultaneous observations of the main ionospheric layer.

  19. A Moderate-resolution Geosynchronous Microwave Sounder

    NASA Technical Reports Server (NTRS)

    Shiue, James

    2004-01-01

    The introduction of microwave radiometers for remote sensing of atmospheric temperature and humidity began in early 1970s, when NASA's Nimbus series experimental satellites tested a number of microwave payloads which are the precursors of today's operational microwave temperature and humidity sounders such as the Advanced Microwave Sounding Unit (AMSU-A and AMSU-B), now flying on several Lower Earth Orbiting (LEO) satellites, notably the National Oceanic and Atmospheric (NOAA)-series weather satellites. The Advanced Technology Microwave Sounder (ATMS) will be the next generation microwave sounder, now being developed by NASA for the future U.S. National Polar-orbiting Operational Environmental Satellites System (NPOESS), slated for operation late this decade. The unique feature of a microwave sensor is its cloud-penetrating capability. And the visible and IR sensors are usually greatly degraded by cloud covers. But under the cloud cover is where the weather can be most "active," and atmospheric measurements are most urgently needed. This unique capability has been well proven by AMSU-A, and AMSU-B on LEO satellites. The same capability is also true for a microwave sounder on a GEO satellite. The key advantage of a sensor on a GEO-platform is its "high temporal resolution." A sensor on a GEO-platform can almost "continuous" monitor a given scene on Earth. On the other hand, the major drawback the GEO-platform is its poor spatial resolution. This is probably the main reason why a geosynchronous microwave sounder has yet to be realized. Take the ATMS as an example. It has a 20 cm diameter antenna (temperature channels), producing a 2.2 degree beam, resulting in a footprint of 32 km (from the NPOESS 833 km orbit). From a GEO-orbit the same 32 km footprint would need an antenna 43 times larger, or 860 cm diameter. We will discuss the needs and advantages of such a GEO-microwave sounder with a straw-man design, and show the expected performance characteristics, such as

  20. Recent advances in the vertical coupling in the Atmosphere-Ionosphere System

    NASA Astrophysics Data System (ADS)

    Knížová, Petra Koucká; Georgieva, Katya; Ward, William; Yiğit, Erdal

    2015-12-01

    Welcome to this special issue of the Journal of Atmospheric and Solar-Terrestrial Physics, dedicated to the investigation of the coupling phenomena in the neutral Atmosphere-Ionosphere System. This special issue covers processes in the Atmosphere-Ionosphere System that significantly influence and/or rule the coupling within the regions. Earth's atmospheric regions are intricately coupled to one another via various dynamical, chemical, and electrodynamic processes. The coupling effects can be seen on the modulation of the waves from the lower to upper atmosphere as well as from low- to high-latitudes, electrodynamic and compositional changes, and plasma irregularities at different latitudinal regions around the globe due to the varying energy inputs. A special attention is paid to the Mesosphere-Lower Thermosphere region that represents a critical region in various coupling processes between the lower/middle atmosphere and the upper atmosphere/ionosphere since it forms physical processes filter and shape the flux of waves ascending through the mesosphere into the overlying thermosphere. Varying energy inputs from the Sun and from the lower atmosphere is one of the topics. Processes contributing to the vertical coupling in the atmosphere are discussed on theoretical basis and with respect to recent and long-term experimental measurements as well. Solar activity represents an important factor that directly or indirectly modulates the coupling processes.

  1. Probing disturbances over canadian ionosphere using advance data analysis of wave decomposition

    NASA Astrophysics Data System (ADS)

    Kherani, Esfhan

    2016-07-01

    Using CHAIN network of GPS receivers, we present disturbances in total electron content (TEC) of the ionosphere on magnetically quiet day of 8 December 2009 and construct travel-time diagram to understand the propagation characteristics of these disturbances. We employ the wave decomposition method to identify the TEC disturbances. We found N-shaped amplified TEC disturbances at higher latitude around 80 N that appear during intensification of ionospheric current at ˜11 UT, suggesting them to be associated with energy input from magnetosphere. These TEC disturbances have spectral peak in between 55-65 minutes, originate in the vicnity of (80N,270W), propagate both southeastward and southwestward with similar velocity ˜80 m/s and arrives at latitude ˜55N around 20 UT. These propagation characteristcs classify them as medium-scale Traveling ionospheric disturbances (MSTIDs) and possibly of gravity wave origin. Noteworthy results of our study are following: (1) presence of dayside MSTIDs whose nightside counterpart is recently reported by Shiokawa et al (2012), (2) long-distance ˜2500 km propagation of dayside MSTIDs that is not reported for the nightside counterpart, (3) dayside MSIDs acquire largest amplitudes in 65-75 during 15-17 UT, similar to the nightside MSTIDs, (4) amplification of amplitudes of MSTIDs in the auroral oval latitudes and (5) identification of driving sources in two latitudes that enable them to propagate long distance.

  2. A Microwave Pressure Sounder

    NASA Technical Reports Server (NTRS)

    Flower, D. A.; Peckham, G. E.

    1978-01-01

    An instrument to measure atmospheric pressure at the earth's surface from an orbiting satellite would be a valuable addition to the expanding inventory of remote sensors. The subject of this report is such an instrument - the Microwave Pressure Sounder (MPS). It is shown that global-ocean coverage is attainable with sufficient accuracy, resolution and observational frequency for meteorological, oceanographic and climate research applications. Surface pressure can be deduced from a measurement of the absorption by an atmospheric column at a frequency in the wing of the oxygen band centered on 60 GHz. An active multifrequency instrument is needed to make this measurement with sufficient accuracy. The selection of optimum operating frequencies is based upon accepted models of surface reflection, oxygen, water vapor and cloud absorption. Numerical simulation using a range of real atmospheres defined by radiosonde observations were used to validate the frequency selection procedure. Analyses are presented of alternative system configurations that define the balance between accuracy and achievable resolution.

  3. Variability in ionospheric total electron content at Mars

    NASA Astrophysics Data System (ADS)

    Mendillo, Michael; Narvaez, Clara; Withers, Paul; Matta, Majd; Kofman, Wlodek; Mouginot, Jeremie

    2013-09-01

    The Mars Express (MEX) mission includes a multi-purpose radio instrument called the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS). When used in its ionospheric-penetrating subsurface sounder (SS) radar mode, a by-product of the MARSIS observations is the ray-path-integral of electron densities, called the total electron content (TEC). We have used the initial TEC database of approximately 1.2 million TEC values spanning the period June 2005 to September 2007 to study the basic characteristics of TEC morphology and variability. We find quantitative agreement between the TEC values measured and those computed from model simulations of global diurnal behavior. With the basic photo-chemistry of the martian ionosphere a well understood process, it is the departures from average conditions that need specification and modeling. Here we use MARSIS TEC to do this quantitatively. We explore the specification of variability using different ways to define it: standard deviations from sample averages versus departures from control curves.

  4. MARSIS observations of the Martian nightside ionosphere dependence on solar wind conditions

    NASA Astrophysics Data System (ADS)

    Diéval, C.; Morgan, D. D.; Němec, F.; Gurnett, D. A.

    2014-05-01

    Despite the absence of solar radiation on the Martian nightside, a weak, irregular, and variable ionosphere is produced there. The nightside ionosphere is thought to be maintained by two main sources: dayside-nightside plasma transport and electron precipitation. Observations by Mars Express (MEX) and Mars Global Surveyor (MGS) have shown that these plasma sources are either hindered or favored by the presence of strong crustal magnetic fields and that these effects are modulated by external parameters, such as the solar wind dynamic pressure and the orientation of the interplanetary magnetic field (IMF). These external drivers are expected to influence the supply of plasma to the nightside and thus the formation of the irregular nightside ionosphere. We here present a statistical study of the Martian ionosphere at solar zenith angle greater than 107° from November 2005 to May 2006, using remote measurements of ionospheric echoes with the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) radar sounder onboard MEX and using MGS-based proxies for the solar wind dynamic pressure and the IMF clock angle. We find that the peak densities increase with the dynamic pressure and also that cases of very high peak density are almost always associated with Westward IMF orientation. We find that, using MEX/ASPERA-3 electron data, these cases often seem to be linked to accelerated electrons. Plasma transport is known to be important in the near nightside. On the other hand, electron precipitation prevails when the dynamic pressure is high enough to compress the ionosphere and in vertical field regions where the IMF orientation matters.

  5. Space Electron Density Gradient Studies using a 3D Embedded Reconfigurable Sounder and ESA/NASA CLUSTER Mission

    NASA Astrophysics Data System (ADS)

    Dekoulis, George

    2016-07-01

    This paper provides a direct comparison between data captured by a new embedded reconfigurable digital sounder, different ground-based ionospheric sounders spread around Europe and the ESA/NASA CLUSTER mission. The CLUSTER mission consists of four identical space probes flying in a formation that allows measurements of the electron density gradient in the local magnetic field. Both the ground-based and the spacecraft instrumentations assist in studying the motion, geometry and boundaries of the plasmasphere. The comparison results are in accordance to each other. Some slight deviations among the captured data were expected from the beginning of this investigation. These small discrepancies are reasonable and seriatim analyzed. The results of this research are significant, since the level of the plasma's ionization, which is related to the solar activity, dominates the propagation of electromagnetic waves through it. Similarly, unusually high solar activity presents serious hazards to orbiting satellites, spaceborne instrumentation, satellite communications and infrastructure located on the Earth's surface. Long-term collaborative study of the data is required to continue, in order to identify and determine the enhanced risk in advance. This would allow scientists to propose an immediate cure.

  6. NeMars empirical model for the dayside martian ionosphere and its use to validate MARSIS instrument techniques: Possible contribution to the Mars International Reference Ionosphere (MIRI)

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Witasse, Olivier; Radicella, Sandro M.; Cartacci, Marco; Orosei, Roberto; Herraiz, Miguel; Rodriguez-Caderot, Gracia

    NeMars is an empirical model of the two main electron density layers of the Martian dayside ionosphere [Sánchez - Cano et al., 2013]. It is mainly based on MARSIS AIS data (Active Ionospheric Sounding from the Mars Advanced Radar and Ionospheric Sounding experiment aboard Mars Express mission) and to a lesser extent on radio-occultation data from the Mars Global Surveyor mission. The model starts from Chapman theory, but allows variation of scale height and altitude of the main layer with solar zenith angle, and assumes the predominance of Chapman-like photochemical processes above 200 km of altitude. The model is able to reproduce with good approximation the main characteristics of both ionospheric regions: electron density and peak altitudes, scale heights, shape of the profiles and Total Electron Content (TEC) of the entire ionosphere. These can be computed in a simple and quick way starting from solar zenith angle, solar flux F10.7 (as a proxy of solar activity), and heliocentric distance. TEC is the integral of the electron density along the vertical direction and constitutes a very useful parameter in characterizing the ionosphere. In particular, in the case of Earth, it is critical for satellite communications and navigation. Independent measurements of the Martian TEC derived from MARSIS subsurface sounding data [Mouginot et al., 2008 and Cartacci et al., 2013] can be used to validate TEC estimates produced by NeMars. However, initial comparisons reveal that TEC estimates based on MARSIS AIS data are not consistent with those obtained from MARSIS subsurface sounding data: this is probably due to the fact that MARSIS in AIS mode is a topside sounder, measuring only the properties of the ionosphere above the maximum plasma frequency, while in subsurface mode it provides an integral information on the TEC for the entire ionosphere. In an attempt to face this problem, the NeMars model outputs are being used to simulate the radio-wave propagation, to study the

  7. Radio sounding in space: magnetosphere and topside ionosphere

    NASA Astrophysics Data System (ADS)

    Reinisch, B. W.; Haines, D. M.; Benson, R. F.; Green, J. L.; Sales, G. S.; Taylor, W. W. L.

    2001-01-01

    Modern sounding techniques have been developed for the space-borne exploration of Earth's magnetosphere and topside ionosphere. Two new satellite instruments will use the advanced techniques of the ground-based Digisondes. The Radio Plasma Imager (RPI), a low-frequency sounder with 500-m dipole antennas designed to sweep from 3 kHz to 3 MHz, will be part of NASA's IMAGE mission to be launched in February 2000 into an elliptical orbit with an altitude at apogee of 7Re. While in the magnetospheric cavity, RPI will receive echoes from the magnetopause and the plasmasphere and will measure the direct response of the magnetosphere's configuration to changes in the solar wind. With three orthogonal dipole antennas (two 500-m tip-to-tip antennas in the spin plane used for transmission and reception, one 20-m antenna along the spin axis for reception only) the arrival angle of returning echoes can be determined with high accuracy. The other instrument is the TOPside Automated Sounder (TOPAS), which was originally conceived for the Ukrainian WARNING mission with a launch date in 2001. Using one antenna for transmission and three orthogonal 10-m antennas for reception, TOPAS will be able to determine the arrival angle of ionospheric echoes and their wave polarization. It will then be possible to automatically scale the topside ionograms and calculate the electron density profiles in real time. Operating as a high-frequency radar, TOPAS will for the first time measure topside plasma velocities by tracking the motions of plasma irregularities.

  8. Instrument technology for magnetosphere plasma imaging from high Earth orbit. Design of a radio plasma sounder. Final report

    SciTech Connect

    Haines, D.M.; Reinisch, B.W.

    1995-01-01

    The use of radio sounding techniques for the study of the ionospheric plasma dates back to G. Briet and M. A. Tuve in 1926. Ground based swept frequency sounders can monitor the electron number density (N{sub e}) as a function of height (the N{sub e} profile). These early instruments evolved into a global network that produced high-resolution displays of echo time delay vs frequency on 35-mm film. These instruments provided the foundation for the success of the International Geophysical Year. The Alouette and International Satellites for Ionospheric Studies (ISIS) programs pioneered the used of spaceborne, swept frequency sounders to obtain N{sub e} profiles of the topside of the ionosphere, from a position above the electron density maximum. Repeated measurements during the orbit produced an orbital plane contour which routinely provided density measurements to within 10%. The Alouette/ISIS experience also showed that even with a high powered transmitter (compared to the low power sounder possible today) a radio sounder can be compatible with other imaging instruments on the same satellite. Digital technology was used on later spacecraft developed by the Japanese (the EXOS C and D) and the Soviets (Intercosmos 19 and Cosmos 1809). However, a full coherent pulse compression and spectral integrating capability, such as exist today for ground-based sounders (Reinisch et al.), has never been put into space. NASA`s 1990 Space Physics Strategy Implementation Study `The NASA Space Physics Program from 1995 to 2010` suggested using radio sounders to study the plasmasphere and the magnetopause and its boundary layers (Green and Fung). Both the magnetopause and plasmasphere, as well as the cusp and boundary layers, can be observed by a radio sounder in a high-inclination polar orbit with an apogee greater than 6 R{sub e} (Reiff et al.; Calvert et al.).

  9. Space Plasma Slab Studies using a new 3D Embedded Reconfigurable MPSoC Sounder

    NASA Astrophysics Data System (ADS)

    Dekoulis, George

    2016-07-01

    This paper presents recent ionospheric slab thickness measurements using a new mobile digital sounder system. The datasets obtained have been compared to the results of existing sounders in operation. The data validity has been verified. The slab thickness data allow constant monitoring of the lower ionosphere revealing the dynamic trends of the physical processes being involved. The prototype offers a tremendous amount of hardware processing power and a previously unseen response time in servicing the input and output data interfaces. This has been enabled by incorporating the latest three-dimensional Ultrascale+ technologies available commercially from the reconfigurable Field Programmable Gate Array (FPGA) computing industry. Furthermore, a previously developed Network-on-Chip (NoC) design methodology has been incorporated for connecting and controlling the application driven multiprocessor network. The system determines electron distributions, aggregate electromagnetic field gradients and plasma current density.

  10. Laser atmospheric wind sounder (LAWS)

    NASA Technical Reports Server (NTRS)

    Beranek, R. G.; Bilbro, J. W.; Fitzjarrald, D. E.; Jones, W. D.; Keller, V. W.

    1989-01-01

    The principle of operation of a space based Doppler lidar wind measuring system is discussed along with laser wavelength selection considerations. Differences in accommodating the Laser Atmospheric Wind Sounder (LAWS) on the Earth Observing System (EOS) polar platform and the Manned Space Station are presented. The impact of the LAWS instrument support subsystems are specifically discussed.

  11. Ionization effects due to solar flare on terrestrial ionosphere

    NASA Technical Reports Server (NTRS)

    Wu, S. T.; Tan, A.

    1976-01-01

    Sudden frequency deviation ionospheric disturbances related to the flares of May 18 and 19, 1973 were observed from the NASA/MSFC high frequency Doppler sounder array system in Huntsville, Alabama. The results are compared with those observed at Table Mountain near Boulder, Colorado and at the University of Hawaii.

  12. The multi-instrumental radio diagnostics of the ionosphere for Space Weather Program

    NASA Astrophysics Data System (ADS)

    Krankowski, Andrzej; Rothkaehl, Hanna; Pulinets, Sergey; Cherniak, Iurii; Zakharenkova, Irina

    2015-04-01

    To give a more detailed and complete understanding of physical plasma processes that govern the solar-terrestrial space, and to develop qualitative and quantitative models of the magnetosphere-ionosphere-thermosphere coupling, it is necessary to design and build the next generation of instruments for space diagnostics and monitoring. Novel ground- based wide-area sensor networks, such as the LOFAR (Low Frequency Array) radar facility, comprising wide band, and vector-sensing radio receivers and multi-spacecraft plasma diagnostics should help to solve outstanding problems of space physics and describe long-term environmental changes. The LOw Frequency ARray - LOFAR - is a new fully digital radio telescope designed for frequencies between 30 MHz and 240 MHz located in Europe. The three new LOFAR stations will be installed until summer 2015 in Poland. The LOFAR facilities in Poland will be distributed among three sites: Lazy (East of Krakow), Borowiec near Poznan and Baldy near Olsztyn. Each site will host one LOFAR station (96 high-band+96 low-band antennas). The new digital radio frequency analyzer (RFA) on board the low-orbiting RELEC satellite was designed to monitor and investigate the ionospheric plasma properties. In addition to the in-situ space plasma measurements the topside sounders will be installed onboard the "Ionosphere" spacecrafts to retrieve the vertical distribution of electron concentration in the topside ionosphere. The first two satellites are scheduled for launch at the first half of 2016. These two-point ground-based and topside ionosphere-located space plasma diagnostic can be a useful new tool for monitoring and diagnosing turbulent plasma properties. In order to improve and validate the large scale and small scale ionospheric structures we will also use the GPS observations collected at IGS/EPN: global and regional TEC maps created with high special and temporal resolution, ROTI maps over the Northern Hemisphere and the data retrieved from

  13. Report from ionospheric science

    NASA Technical Reports Server (NTRS)

    Raitt, W. J.; Banks, Peter M.; Nagy, A. F.; Chappell, C. R.

    1989-01-01

    The general strategy to advance knowledge of the ionospheric component of the solar terrestrial system should consist of a three pronged attack on the problem. Ionospheric models should be refined by utilization of existing and new data bases. The data generated in the future should emphasize spatial and temporal gradients and their relation to other events in the solar terrestrial system. In parallel with the improvement in modeling, it will be necessary to initiate a program of advanced instrument development. In particular, emphasis should be placed on the area of improved imaging techniques. The third general activity to be supported should be active experiments related to a better understanding of the basic physics of interactions occurring in the ionospheric environment. These strategies are briefly discussed.

  14. THz Limb Sounder (TLS) for Lower Thermospheric Wind, Oxygen Density, and Temperature

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Yee, Jeng-Hwa; Schlecht, Erich; Mehdi, Imran; Siles, Jose; Drouin, Brian J.

    2016-01-01

    Neutral winds are one of the most critical measurements in the lower thermosphere and E region ionosphere (LTEI) for understanding complex electrodynamic processes and ion-neutral interactions. We are developing a high-sensitivity, low-power, noncryogenic 2.06 THz Schottky receiver to measure wind profiles at 100-140 km. The new technique, THz limb sounder (TLS), aims to measure LTEI winds by resolving the wind-induced Doppler shift of 2.06 THz atomic oxygen (OI) emissions. As a transition between fine structure levels in the ground electronic state, the OI emission is in local thermodynamic equilibrium(LTE) at altitudes up to 350km. This LTE property, together with day-and-night capability and small line-of-sight gradient, makes the OI limb sounding a very attractive technique for neutral wind observations. In addition to the wind measurement, TLS can also retrieve [OI] density and neutral temperature in the LTEI region. TLS leverages rapid advances in THz receiver technologies including subharmonically pumped (SHP)mixers and Schottky-diode-based power multipliers. Current SHP Schottky receivers have produced good sensitivity for THz frequencies at ambient environment temperatures (120-150 K), which are achievable through passively cooling in spaceflight. As an emerging technique, TLS can fill the critical data gaps in the LTEI neutral wind observations to enable detailed studies on the coupling and dynamo processes between charged and neutral molecules.

  15. THz limb sounder (TLS) for lower thermospheric wind, oxygen density, and temperature

    NASA Astrophysics Data System (ADS)

    Wu, Dong L.; Yee, Jeng-Hwa; Schlecht, Erich; Mehdi, Imran; Siles, Jose; Drouin, Brian J.

    2016-07-01

    Neutral winds are one of the most critical measurements in the lower thermosphere and E region ionosphere (LTEI) for understanding complex electrodynamic processes and ion-neutral interactions. We are developing a high-sensitivity, low-power, noncryogenic 2.06 THz Schottky receiver to measure wind profiles at 100-140 km. The new technique, THz limb sounder (TLS), aims to measure LTEI winds by resolving the wind-induced Doppler shift of 2.06 THz atomic oxygen (OI) emissions. As a transition between fine structure levels in the ground electronic state, the OI emission is in local thermodynamic equilibrium (LTE) at altitudes up to 350 km. This LTE property, together with day-and-night capability and small line-of-sight gradient, makes the OI limb sounding a very attractive technique for neutral wind observations. In addition to the wind measurement, TLS can also retrieve [OI] density and neutral temperature in the LTEI region. TLS leverages rapid advances in THz receiver technologies including subharmonically pumped (SHP) mixers and Schottky-diode-based power multipliers. Current SHP Schottky receivers have produced good sensitivity for THz frequencies at ambient environment temperatures (120-150 K), which are achievable through passively cooling in spaceflight. As an emerging technique, TLS can fill the critical data gaps in the LTEI neutral wind observations to enable detailed studies on the coupling and dynamo processes between charged and neutral molecules.

  16. Comparative ionospheres

    NASA Astrophysics Data System (ADS)

    Cravens, T.

    2003-04-01

    Ionospheres are created as a consequence of the ionization of the neutral atoms and molecules in a planet’s upper atmosphere either by solar radiation or by fast charged particles. Ionospheres have been detected at all the planets except for Mercury and Pluto, either remotely or by in situ instruments. Active comets have ionospheres as do many planetary satellites, including Io, Europa, Ganymede, Titan, and Triton. A comparative review of ionospheres throughout the solar system will be given in this paper. Observations and theoretical models will be included in the review.

  17. Modeling the martian ionosphere

    NASA Astrophysics Data System (ADS)

    Matta, Majd Mayyasi

    The accessibility of the Martian atmosphere to spacecraft provides an opportunity to study an ionosphere that differs from our own. Yet, despite the half century of measurements made at Mars, the current state of the neutral atmosphere and its embedded plasma (ionosphere) remains largely uncharacterized. In situ measurements of the neutral and ionized constituents versus height exist only from the two Viking Landers from the 1970s. Subsequent satellite and remote sensing data offer sparse global coverage of the ionosphere. Thermal characteristics of the plasma environment are not well understood. Patchy crustal magnetic fields interact with the Martian plasma in a way that has not been fully studied. Hence, investigating the coupled compositional, thermal and crustal-field-affected properties of the ionosphere can provide insight into comparative systems at Earth and other planets, as well as to atypical processes such as the solar wind interaction with topside ionospheric plasma and associated pathways to escape. Ionospheric models are fundamental tools that advance our understanding of complex plasma systems. A pre-existing one-dimensional model of the Martian ionosphere has been upgraded to include more comprehensive chemistry and transport physics. This new BU Mars Ionosphere Model has been used to study the composition, thermal structure and dynamics of the Martian ionosphere. Specifically: the sensitivity of the abundance of ions to neutral atmospheric composition has been quantified, diurnal patterns of ion and electron temperatures have been derived self-consistently using supra-thermal electron heating rates, and the behavior of ionospheric plasma in crustal field regions was simulated by constructing a two-dimensional ionospheric model. Results from these studies were compared with measurements and show that (1) ion composition at Mars is highly sensitive to the abundance of neutral molecular and atomic hydrogen, (2) lighter ions heat up more efficiently

  18. Advanced Ion Mass Spectrometer for Giant Planet Ionosphere, Magnetospheres and Moons

    NASA Astrophysics Data System (ADS)

    Sittler, Edward; Cooper, John; Paschalidis, Nick; Jones, Sarah; Brinkerhoff, William; Paterson, William; Ali, Ashraf; Coplan, Michael; Chornay, Dennis; Sturner, Steve; Benna, Mehdi; Bateman, Fred; Fontaine, Dominique; Verdeil, Christophe; Andre, Nicolas; Blanc, Michel; Wurz, Peter

    2017-01-01

    We present our Advanced Ion Mass Spectrometer (AIMS) for outer planet missions which has been under development from various NASA sources (NASA Living with a Star Instrument Development (LWSID), NASA Astrobiology Instrument Development (ASTID), NASA Goddard Internal Research and Development (IRAD)s) to measure elemental, isotopic, and simple molecular composition abundances of 1 V to 25 kV hot ions with wide field-of-view (FOV) in the 1 - 60 amu mass range at mass resolution M/ ΔM <= 60 over a wide dynamic range of particle intensities and penetrating radiation background from the inner magnetospheres of Jupiter and Saturn to the outer magnetospheric boundary regions and the upstream solar wind. This instrument will work for both spinning spacecraft and 3-axis stabilized spacecraft. AIMS will measure the ion velocity distribution functions (VDF) for the individual ion species from which velocity moments will give their ion density, flow velocity and temperature.

  19. Instrument technology for magnetosphere plasma imaging from high Earth orbit. Design of a radio plasma sounder

    NASA Technical Reports Server (NTRS)

    Haines, D. Mark; Reinisch, Bodo W.

    1995-01-01

    The use of radio sounding techniques for the study of the ionospheric plasma dates back to G. Briet and M. A. Tuve in 1926. Ground based swept frequency sounders can monitor the electron number density (N(sub e)) as a function of height (the N(sub e) profile). These early instruments evolved into a global network that produced high-resolution displays of echo time delay vs frequency on 35-mm film. These instruments provided the foundation for the success of the International Geophysical Year (1958). The Alouette and International Satellites for Ionospheric Studies (ISIS) programs pioneered the used of spaceborne, swept frequency sounders to obtain N(sub e) profiles of the topside of the ionosphere, from a position above the electron density maximum. Repeated measurements during the orbit produced an orbital plane contour which routinely provided density measurements to within 10%. The Alouette/ISIS experience also showed that even with a high powered transmitter (compared to the low power sounder possible today) a radio sounder can be compatible with other imaging instruments on the same satellite. Digital technology was used on later spacecraft developed by the Japanese (the EXOS C and D) and the Soviets (Intercosmos 19 and Cosmos 1809). However, a full coherent pulse compression and spectral integrating capability, such as exist today for ground-based sounders (Reinisch et al., 1992), has never been put into space. NASA's 1990 Space Physics Strategy Implementation Study "The NASA Space Physics Program from 1995 to 2010" suggested using radio sounders to study the plasmasphere and the magnetopause and its boundary layers (Green and Fung, 1993). Both the magnetopause and plasmasphere, as well as the cusp and boundary layers, can be observed by a radio sounder in a high-inclination polar orbit with an apogee greater than 6 R(sub e) (Reiff et al., 1994; Calvert et al., 1995). Magnetospheric radio sounding from space will provide remote density measurements of

  20. Sounder-updated statistical model predictions of maximum usable frequency for HF sky wave predictions. Memorandum report

    SciTech Connect

    Reilly, M.H.; Daehler, M.

    1985-10-30

    Measured solar parameters, such as sunspot number or 10.7 cm flux, have traditionally been used as inputs to drive statistical-model predictions of maximum usable frequencies (MUFs) on HF radio sky wave paths of interest. Much greater accuracy can be obtained by using ionospheric sounder inputs to drive or update statistical-model predictions, and this is demonstrated here using oblique-incidence sounder data from the DoD Solid Shield exercises on May 12-14, 1981. From analysis of ionograms collected for several paths every fifteen minutes, it is found that deployment of a reasonable number of sounders in a large area, in order to update the simple statistical model, MINIMUF, yields MUF prediction capability on unsounded communication paths in the area within 0.4 MHz rms error. This value is obtained from real-time updating and a spatial interpolation process developed here, whereby data at sounder control points is interpolated to ionospheric reflection points for communication paths of interest. The results from the interpolation are found to be at least 20-30% more accurate than updating at any one of the nearby sounder control points. The updating procedure applies under day and night conditions, and also works well in a forecasting mode (not real-time), where it is found to work better in this case than a statistical trend line approach for daytime forecasting. (Author)

  1. Advanced Ion Mass Spectrometer for Giant Planet Ionospheres, Magnetospheres and Moons

    NASA Astrophysics Data System (ADS)

    Sittler, EC; Cooper, JF; Paschalidis, N.; Jones, SL; Rodriguez, M.; Ali, A.; Coplan, MA; Chornay, DJ; Sturner; Bateman, FB; Andre, N.; Fedorov, A.; Wurz, P.

    2015-10-01

    The Advanced Ion Composition Spectrometer (AIMS) has been under development from various NASA sources (NASA LWSID, NASA ASTID, NASA Goddard IRADs) to measure elemental, isotopic, and simple molecular composition abundances of 1 eV/e to 25 keV/e hot ions with wide field-of-view (FOV) in the 1 - 60 amu mass range at mass resolution M/ΔM ≤ 60 over a wide dynamic range of intensities and penetrating radiation background from the inner magnetospheres of Jupiter and Saturn to the outer magnetospheric boundary regions and the upstream solar wind. This instrument will work for both spinning spacecraft and 3-axis stabilized spacecraft with wide field-of-view capability in both cases. It will measure the ion velocity distribution functions (IVDF) for the individual ion species; ion velocity moments of the IVDF will give the fluid parameters (density, flow velocity and temperature) of the individual ion species. Outer planet mission applications are Io Observer, Jupiter Europa Orbiter/Europa Clipper, Enceladus Orbiter, and Uranus Orbiter as described in the decadal survey, but would also be valuable for inclusion on other missions to outer planet destinations such as Saturn- Titan and Neptune-Triton and for future missions to terrestrial planets, Venus and Mars, the Moon, asteroids, and comets, and of course for geospace applications to the Earth.

  2. Radar soundings of the ionosphere of Mars.

    PubMed

    Gurnett, D A; Kirchner, D L; Huff, R L; Morgan, D D; Persoon, A M; Averkamp, T F; Duru, F; Nielsen, E; Safaeinili, A; Plaut, J J; Picardi, G

    2005-12-23

    We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere to a wide variety of oblique and diffuse echoes. The oblique echoes are believed to arise mainly from ionospheric structures associated with the complex crustal magnetic fields of Mars. Echoes at the electron plasma frequency and the cyclotron period also provide measurements of the local electron density and magnetic field strength.

  3. Oblique-incidence sounder measurements with absolute propagation delay timing

    SciTech Connect

    Daehler, M.

    1990-05-03

    Timing from the Global Position Satellite (GPS) system has been applied to HF oblique incidence sounder measurements to produce ionograms whose propagation delay time scale is absolutely calibrated. Such a calibration is useful for interpreting ionograms in terms of the electron density true-height profile for the ionosphere responsible for the propagation. Use of the time variations in the shape of the electron density profile, in conjunction with an HF propagation model, is expected to provide better near-term (1-24 hour) HF propagation forecasts than are available from current updating systems, which use only the MUF. Such a capability may provide the basis for HF frequency management techniques which are more efficient than current methods. Absolute timing and other techniques applicable to automatic extraction of the electron-density profile from an ionogram will be discussed.

  4. Geostationary-satellite beacon-receiver array for studies of ionospheric irregularities

    SciTech Connect

    Carlos, R.C.; Jacobson, A.R.; Wu, Guanghui.

    1992-01-01

    Ionospheric irregularities can be studied by various techniques. These include widely spaced Doppler sounders or ionosondes, Faraday rotation polarimetry, and two-frequency differential Doppler, and radio interferometry. With geostationary satellites, one usually uses Faraday rotation of the beacon signal to measure the ionospheric TEC. With a network of polarimeters, the horizontal wave parameters of Traveling Ionospheric Disturbances (TIDS) can be deduced, but the shortcoming of this technique is its poor sensitivity. This paper describes a geostationary-satellite beacon-receiver array at Los Alamos, New Mexico, which will be employed for the studying of ionospheric irregularities, especially the fine-scale TIDS.

  5. Geostationary-satellite beacon-receiver array for studies of ionospheric irregularities

    SciTech Connect

    Carlos, R.C.; Jacobson, A.R.; Wu, Guanghui

    1992-09-01

    Ionospheric irregularities can be studied by various techniques. These include widely spaced Doppler sounders or ionosondes, Faraday rotation polarimetry, and two-frequency differential Doppler, and radio interferometry. With geostationary satellites, one usually uses Faraday rotation of the beacon signal to measure the ionospheric TEC. With a network of polarimeters, the horizontal wave parameters of Traveling Ionospheric Disturbances (TIDS) can be deduced, but the shortcoming of this technique is its poor sensitivity. This paper describes a geostationary-satellite beacon-receiver array at Los Alamos, New Mexico, which will be employed for the studying of ionospheric irregularities, especially the fine-scale TIDS.

  6. Ionosphere research

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A report is presented on on-going research projects in ionospheric studies. The topics discussed are planetary atmospheres, E and F region, D region, mass spectrometer measurements, direct measurements and atmospheric reactions.

  7. Ionospheric research

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Data from research on ionospheric D, E, and F, regions are reported. Wave propagation, mass spectrometer measurements, and atmospheric reactions of HO2 with NO and NO2 and NH2 with NO and O2 are summarized.

  8. Stimulation of the Harris instability in the ionosphere

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1974-01-01

    Observations made with a sweep frequency rf sounder on the satellite ISIS 1 in the topside ionosphere are reported, and the interpretation of diffuse signals at the lower harmonics of the electron cyclotron frequency is discussed. These signals are attributed to the stimulation of Harris instabilities of longitudinal plasma waves at multiples of the cyclotron frequency in a single electron distribution. The Harris instability is excited most readily when the frequency is near the midpoint between the harmonics of the cyclotron frequency. The cause of these instabilities is the large electron velocity anisotropy which results from collisionless cyclotron damping of the energy from the high power sounder pulse.

  9. Mars Climate Sounder (Artist's Concept)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This artist's concept of NASA's Mars Reconnaissance Orbiter at Mars features one of its instruments -- the Mars Climate Sounder -- in action. Using nine channels across the visible and thermal infrared ranges of the spectrum, the Mars Climate Sounder looks first at space through the atmosphere above the horizon of Mars to get a vertical profile with temperature, pressure, dust and water vapor concentration measurements every 5 kilometers (3 miles) vertically from the ground to about 80 kilometers (about 50 miles) high. It also looks down onto the planet to get surface temperature and column abundances of dust and water vapor between the spacecraft and the surface.

    These 'profiles' and surface measurements are combined into daily, three-dimensional global weather maps for both daytime and nighttime. Observations will be made through the martian year to characterize the large seasonal variations in atmospheric dust loading, humidity and thermal structure, providing scientists with the same type of information meteorologists use to understand and predict weather and climate here on Earth.

  10. Advanced Moisture and Temperature Sounder (AMTS) study

    NASA Technical Reports Server (NTRS)

    Kaplan, L. D.; Isaacs, R. G.; Worsham, R. D.; Deblonde, G.

    1985-01-01

    Retrieval of tropospheric humidity profiles from satellite-based upwelling radiances are shown to be improved by using physical methods for obtaining first-guess profiles as well as for inverting the radiative transfer equation by relaxation. The first guess is based on an empirically verified hypothesis, from theoretical considerations, that the brightness temperature corresponding to the radiance should be approximately equal to the actual temperatue at a channel-invariant optical depth provided that the surface and stratospheric contributions to the radiance are small. Even greater improvement of retrieved humidity profiles can be accomplished by increasing the number of channels used and by selecting their spectral location and bandpass to obtain sharper independent weighting functions. For example, the AMTS system, with high resolution water channels at 1650, 1700, 1839, 1850 and 1930 cm, is shown to be capable of reducing the retrieved water vapor errors in 200 mb thick layers by a factor of two or three relative to the HIRS-2 system errors. Expected AMTS errors in tropical layer water content are particularly low, less than 20% at all levels, and of the order of 10% or less in the middle troposphere.

  11. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop

    DTIC Science & Technology

    2013-05-01

    mechanisms of relativistic electrons around Earth during geospace storms . The project consists of the ERG satellite, ground-based network observations...is located inside the subauroral region and is mapped near the plasma pause; and during storms , it is inside the auroral zone. As a result, it was...Positioning System (GPS), and concerns about space weather. Plasma instabilities within the global ionosphere, especially during major magnetic storms

  12. Ionospheric Analysis and Ionospheric Modeling

    DTIC Science & Technology

    1975-07-01

    ionospheric data by numerical methods, ITU Tellecomm. Jour. 29, 129-149 4. Edwards, W. R., Rush, C. M. and Miller, D. C. (1975) Studies on the...data including 1958 and 1964 vertical incidence ionosonde measurements, and optical and satellite observations. The repre- sentation of the different...2) Jones, W. B,., and Gallet, R. M. (1962) Representation of divinaland geographic. variatioms of ionospheric data by numerical methods, ITU TeUeconrm

  13. Dayside induced magnetic field in the ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Akalin, F.; Morgan, D. D.; Gurnett, D. A.; Kirchner, D. L.; Brain, D. A.; Modolo, R.; Acuña, M. H.; Espley, J. R.

    2010-03-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the Mars Express spacecraft has occasionally displayed surprising features. One such feature is the occurrence of a series of broadband, low-frequency echoes at equally spaced delay times after the sounder transmitter pulse. The interval between the echoes has been shown to be at the cyclotron period of electrons orbiting in the local magnetic field. The electrons are believed to be accelerated by the large voltages applied to the antenna by the sounder transmitter. Measurements of the period of these "electron cyclotron echoes" provide a simple technique for determining the magnitude of the magnetic field near the spacecraft. These measurements are particularly useful because Mars Express carries no magnetometer, so this is the only method available for measuring the magnetic field magnitude. Using this technique, results are presented showing the large scale structure of the draped field inside the magnetic pile-up boundary. The magnitude of the draped field is shown to vary from about 40 nT at a solar zenith angle of about 25°, to about 25 nT at a solar zenith angle of 90°. The results compare favorably with similar results from the Mars Global Surveyor spacecraft. A fitting technique is developed to derive the vector direction and magnitude of the draped magnetic field in cases where the spacecraft passes through regions with significant variation in the crustal field. The magnetic field directions are consistent with current knowledge of the draping geometry of the magnetic field around Mars.

  14. Nonlinear Landau damping in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kiwamoto, Y.; Benson, R. F.

    1978-01-01

    A model is presented to explain the non-resonant waves which give rise to the diffuse resonance observed near 3/2 f sub H by the Alouette and ISIS topside sounders, where f sub H is the ambient electron cyclotron frequency. In a strictly linear analysis, these instability driven waves will decay due to Landau damping on a time scale much shorter than the observed time duration of the diffuse resonance. Calculations of the nonlinear wave particle coupling coefficients, however, indicate that the diffuse resonance wave can be maintained by the nonlinear Landau damping of the sounder stimulated 2f sub H wave. The time duration of the diffuse resonance is determined by the transit time of the instability generated and nonlinearly maintained diffuse resonance wave from the remote short lived hot region back to the antenna. The model is consistent with the Alouette/ISIS observations, and clearly demonstrates the existence of nonlinear wave-particle interactions in the ionosphere.

  15. Ionospheric specification with analytical profilers: Evidences of non-Chapman electron density distribution in the upper ionosphere

    NASA Astrophysics Data System (ADS)

    Verhulst, T.; Stankov, S. M.

    2015-04-01

    In relation to the development of an operational ionospheric monitoring and imaging system, the most frequently used analytical ionospheric profilers (Chapman, Epstein, Exponential) were investigated in terms of suitability for topside ionosphere modelling. For the purpose, topside sounder measurements onboard Alouette and ISIS satellites have been analysed. We have come to the conclusion that the use of the Chapman profiler should be exercised with precaution as there are evidences that there are conditions when other profilers are better fit for modelling purposes. This is highlighted during ionospheric disturbances (e.g. during geomagnetic storms), when the shape of the topside electron density distribution might be better described by an Epstein profiler rather than a Chapman profiler.

  16. Submillimeter Planetary Atmospheric Chemistry Exploration Sounder

    NASA Technical Reports Server (NTRS)

    Schlecht, Erich T.; Allen, Mark A.; Gill, John J.; Choonsup, Lee; Lin, Robert H.; Sin, Seth; Mehdi, Imran; Siegel, Peter H.; Maestrini, Alain

    2013-01-01

    Planetary Atmospheric Chemistry Exploration Sounder (SPACES), a high-sensitivity laboratory breadboard for a spectrometer targeted at orbital planetary atmospheric analysis. The frequency range is 520 to 590 GHz, with a target noise temperature sensitivity of 2,500 K for detecting water, sulfur compounds, carbon compounds, and other atmospheric constituents. SPACES is a prototype for a powerful tool for the exploration of the chemistry and dynamics of any planetary atmosphere. It is fundamentally a single-pixel receiver for spectral signals emitted by the relevant constituents, intended to be fed by a fixed or movable telescope/antenna. Its front-end sensor translates the received signal down to the 100-MHz range where it can be digitized and the data transferred to a spectrum analyzer for processing, spectrum generation, and accumulation. The individual microwave and submillimeter wave components (mixers, LO high-powered amplifiers, and multipliers) of SPACES were developed in cooperation with other programs, although with this type of instrument in mind. Compared to previous planetary and Earth science instruments, its broad bandwidth (approx. =.13%) and rapid tunability (approx. =.10 ms) are new developments only made possible recently by the advancement in submillimeter circuit design and processing at JPL.

  17. Cloud Clearing of Infrared Sounder Radiances.

    NASA Astrophysics Data System (ADS)

    Rizzi, R.; Serio, C.; Kelly, G.; Tramutoli, V.; McNally, A.

    1994-02-01

    R. RizziEuropean Centre for Medium-Range Weather Forecasts, Reading, England European Organization for the Exploitation of Meteorological Satellites, Darmstadt, Germany C. SerioDipartimento di Scienze Fisiche, Napoli, Italy G. KellyEuropean Centre for Medium-Range Weather Forecasts, Reading, England V. TramutoliDipartimento di Ingegneria e Fisica deil' Ambiente, Potenza, Italy A. McNallyEuropean Centre for Medium-Range Weather Forecasts, Reading, EnglandThe paper compares the performance of three different schemes for computing clear-sky brightness temperature from cloud-affected measurements. Both the ability to detect clouds and to estimate the equivalent clear-sky brightness temperature are examined. Simulated brightness temperatures computed from the ECMWF operational analysis are used as a reference, together with Advanced Very High Resolution Radiometer (AVHRR)-derived sea surface temperature and cloud content within High-Resolution Infrared Radiation Sounder (HIRS) fields of view. Cloud masks obtained from the cloud-detection schemes are compared with cloud masks obtained from AVHRR data; clear-column brightness temperatures for HIRS/2 channels 4, 7, and 13 are compared with the simulated ones; simulated clear-column brightness temperatures in the HIRS/2 window channel 8 are validated with equivalent products from AVHRR data. The comparison highlights some problems in the operational implementation of the NESDIS cloud-clearing scheme and with the operational filtering scheme of the United Kingdom Meteorological Office.

  18. RF Charging of Topside Sounder Spacecraft

    NASA Astrophysics Data System (ADS)

    James, H. G.

    1998-11-01

    Evidence concerning RF-induced charging of topside sounder spacecraft is reviewed. The most direct evidence from the orbital sounders ISIS II and Cosmos 1809 is observations of sounder-accelerated ions at energies up to a several tens of electron-volts. These ions are interpreted as the flux to the spacecraft body to discharge the negative electrical potential induced on the body by the action of sounder near fields on ambient electrons. The situation on ISIS II was modeled for frequencies well below the electron plasma and gyrofrequencies, fp and fc , respectively. During the RF pulse, the body was found to go to a negative potential about equal to the peak amplitude of the voltage waveform applied to the sounder dipole. Other observations from the sounders at frequencies around fp and fc, including "floating" resonant signals on ionograms and impedance measurements, attest to RF sheaths and hence to charging. The OEDIPUS-C spacecraft potential measurement has provided proof of RF charging through the whole range of electron characteristic frequencies.

  19. Online data base of satellite sounder and insitu measurements covering two solar cycles

    NASA Astrophysics Data System (ADS)

    Bilitza, D.; Reinisch, B.; Benson, R.; Grebowsky, J.; Papitashvili, N.; Huang, X.; Schar, W.; Hills, K.

    Accurate descriptions of the solar cycle variations of ionospheric parameters are an important goal of ionospheric modeling. Reliable predictions of these variations are of essential importance for almost all applications of ionospheric models. Unfortunately there are very few global data sources that cover a solar cycle or more. In an effort to expand the solar cycle coverage of data readily available for ionospheric modeling, we have processed a large number of satellite data sets from the sixties, seventies, and early eighties and have made them online accessible as part of NSSDC's ftp archive (http://nssdcftp.gsfc.nasa.gov/spacecraft data/) and it's ATMOWeb retrieval and plotting system (http://nssdc.gsfc.nasa.gov/atmoweb/). We report about two data restoration efforts supported through NASA's Applied Information Systems Research Program (AISRP). The first project deals with insitu data from a large number of US, Canadian, Japanese and German satellites that measured ionospheric densities and temperatures from 1964 to 1983. The accumulated data base includes data from the BE-B, DME-A, AE-B, Alouette 2, ISIS 1, 2, OGO-6, AEROS A, AE-C, -D, -E, Hinotori, ISS-b and DE-2 satellite missions. The second project involves the production of digital topside sounder ionograms from the ISIS 1 and 2 satellites and their subsequent inversion to produce electron-density profiles. Approximately 340,000 ionograms are available from NSSDC as of July 2002. An automatic topside ionogram scaler with true height algorithm (TOPIST) was developed as part of this project and is now being used to obtain electron density profiles from these ionograms. Providing global coverage over more than two solar cycles the database established by this two projects is a valuable asset for improvements of the International Reference Ionosphere model and for ionospheric research.

  20. Multipoint Geospace Science in 3D: The Paired Ionosphere-Thermosphere Orbiters(PITO) Mission

    NASA Technical Reports Server (NTRS)

    Clemmons, J.; Walterscheid, R.; Nigg, D.; Judnick, D.; Lang, J.; Spann, J.

    2010-01-01

    The science enabled by the Paired Ionosphere-Thermosphere Orbiters (PITO) mission is described and discussed. PITO has been designed to provide the concurrent, three-dimensional, multipoint measurements needed to advance geospace science while staying within a stringent resource envelope. The mission utilizes a pair of orbiting vehicles in eccentric, high-inclination, coplanar orbits. The orbits have arguments of perigee that differ by 180 degrees and are phased such that one vehicle is at perigee (200 km) while the second is at apogee (2000 km). Half an orbit later, the vehicles switch positions. Three complementary types of measurements exploit this scenario: local, in-situ measurements on both satellites, two-dimensional imaging from the higher satellite, and vertical sounders. The main idea is that two-dimensional context information for the low-altitude measurements is obtained by the high altitude imagers, while information on the third dimension is provided by vertical profiling. Such an observation system is capable of providing elements of global coverage, regional coverage, and concurrent coverage in three dimensions. Science goals are presented, as are the results of a detailed implementation plan, including several trade studies on key elements of the mission. The conclusion is that the mission would enable significant new understanding of the ionosphere-thermosphere system within a resource envelope that is consistent with that of NASA's Medium Explorer (MIDEX) line of science missions.

  1. Ionospheric Physics.

    DTIC Science & Technology

    1982-10-07

    system design and ionospheric modification and con- ~trol. In this report, the S3-4 satellite data analyses is summarized. D, JAN73 1473 EDITION OF INOV ...wavelength distribution of solar radiation and the time variations of such emissions as well as the resonant scattering of solar radiation by...ratio square (Ie/I1) 2), is more inside the depletions in most of the depletions suggesting more molecular ions inside the depletions. o The power

  2. Bimodal Solar Wind-Magnetosphere-Ionosphere Coupling

    NASA Astrophysics Data System (ADS)

    Siscoe, G.

    2005-05-01

    Regarding its coupling to the solar wind, the magnetosphere-ionosphere system appears to be schizophrenic. That is, it seems to manifest two modes with contradictory qualities, modes that alternate depending on solar wind conditions. Normal conditions elicit the normal mode (aka the solar wind-dominated mode). But extreme conditions bring out the un-normal mode (aka the ionosphere-dominated mode). This talk emphasizes the un-normal, ionosphere-dominated mode, which makes its presence during great magnetic storms. Then the magnetosphere-confining Chapman-Ferraro current system fades away to be replaced by the region 1 currents system which links the now dominant ionosphere to the whole of geospace out to and including the bow shock. Dst no longer responds to the ram pressure of the solar wind. The electrical potential across the polar cap stops growing as solar wind driving strengthens. Instead, it becomes bound to ionospheric conductance, which as the storm intensifies transforms under local instability. The ionosphere appears to lose its grip on magnetospheric convection, although this is not certain. The plasmasphere is stripped away, most likely to feed (by global circulation) an intensifying ring current. The outer magnetosphere begins a series of slow, macroscale convulsions. Huge parallel potentials possibly develop in the magnetosphere's outer regions, reacting against the ionosphere's domination. Compared to the solar wind-dominated magnetosphere, the ionosphere-dominated magnetosphere is comparatively unknown and, so, provides opportunities for significantly advancing our understanding of the coupled solar wind-magnetosphere-ionosphere system.

  3. Nonlinear Landau damping in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kiwamoto, Y.; Benson, R. F.

    1979-01-01

    A model which explains the nonresonant waves which produce the diffuse resonance observed near 3/2 f(H) by the Alouette and Isis topside sounders, where f(H) is the ambient electron cyclotron frequency, is presented. These waves are the result of plasma wave instabilities driven by anisotropic electron velocity distributions initiated by the high-power short-duration sounder pulse. Calculations of the nonlinear wave-particle coupling coefficients show that the diffuse resonance wave can be maintained by nonlinear Landau damping of the sounder-stimulated 2f(H) wave which is observed with a time duration longer than that of the diffuse resonance wave. The time duration of the diffuse resonance is determined by the transit time of the instability-generated and nonlinearly maintained diffuse resonance wave from the remote short-lived hot region back to the antenna. The model is consistent with the Alouette/Isis observations and it demonstrates the existence of nonlinear wave-particle interactions in the ionosphere.

  4. Role of ionospheric conductance in magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Tapas

    Magnetosphere-ionosphere (MI) coupling has been studied for a long time. However, not much work has been done on a systematic understanding of the relation between ionospheric Pedersen conductance, its effect on the evolution and modification of field-aligned currents (FACs), and the influence of conductance and FACs on the formation of parallel electric fields which cause particle precipitation. Though the roles of ionospheric conductance gradients for FACs and parallel electric field evolution are directly related, they are poorly understood. This dissertation advances the understanding of these areas and all results of this study are based on numerical simulations that employ a three-dimensional - two-fluid (ions and neutrals) simulation code. The first part of this dissertation presents a systematic study of the magnetospheric and ionospheric influences on the evolution and modification of FACs with focus on the role of ionospheric Pedersen conductance and its gradients. FACs are typically generated in the magnetosphere and are carried into the ionosphere by Alfven waves. During their reflection from the ionosphere these FACs are modified depending on the magnitude and distribution of ionospheric conductance. For conductance gradients along the polarization of the wave, strong Pedersen currents can be generated which in turn enhance the FAC as well. The second part of this dissertation addresses the properties and evolution of parallel electric fields in an attempt to better understand the formation of discrete auroral arcs in response to the evolution of FACs for predetermined ionospheric conductance patterns. Frequently, auroral acceleration is believed to occur through U or V shaped potentials. Therefore, this part examines the properties of localized parallel electric fields in a uniform magnetic field. It is demonstrated that localized parallel electric fields generate magnetic flux in the absence of source of free energy. It is also shown that parallel

  5. Assessment of error propagation in ultraspectral sounder data via JPEG2000 compression and turbo coding

    NASA Astrophysics Data System (ADS)

    Olsen, Donald P.; Wang, Charles C.; Sklar, Dean; Huang, Bormin; Ahuja, Alok

    2005-08-01

    Research has been undertaken to examine the robustness of JPEG2000 when corrupted by transmission bit errors in a satellite data stream. Contemporary and future ultraspectral sounders such as Atmospheric Infrared Sounder (AIRS), Cross-track Infrared Sounder (CrIS), Infrared Atmospheric Sounding Interferometer (IASI), Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS), and Hyperspectral Environmental Suite (HES) generate a large volume of three-dimensional data. Hence, compression of ultraspectral sounder data will facilitate data transmission and archiving. There is a need for lossless or near-lossless compression of ultraspectral sounder data to avoid potential retrieval degradation of geophysical parameters due to lossy compression. This paper investigates the simulated error propagation in AIRS ultraspectral sounder data with advanced source and channel coding in a satellite data stream. The source coding is done via JPEG2000, the latest International Organization for Standardization (ISO)/International Telecommunication Union (ITU) standard for image compression. After JPEG2000 compression the AIRS ultraspectral sounder data is then error correction encoded using a rate 0.954 turbo product code (TPC) for channel error control. Experimental results of error patterns on both channel and source decoding are presented. The error propagation effects are curbed via the block-based protection mechanism in the JPEG2000 codec as well as memory characteristics of the forward error correction (FEC) scheme to contain decoding errors within received blocks. A single nonheader bit error in a source code block tends to contaminate the bits until the end of the source code block before the inverse discrete wavelet transform (IDWT), and those erroneous bits propagate even further after the IDWT. Furthermore, a single header bit error may result in the corruption of almost the entire decompressed granule. JPEG2000 appears vulnerable to bit errors in a noisy channel of

  6. ISIS Topside-Sounder Plasma-Wave Investigations as Guides to Desired Virtual Wave Observatory (VWO) Data Search Capabilities

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Fung, Shing F.

    2008-01-01

    Many plasma-wave phenomena, observed by space-borne radio sounders, cannot be properly explained in terms of wave propagation in a cold plasma consisting of mobile electrons and infinitely massive positive ions. These phenomena include signals known as plasma resonances. The principal resonances at the harmonics of the electron cyclotron frequency, the plasma frequency, and the upper-hybrid frequency are well explained by the warm-plasma propagation of sounder-generated electrostatic waves, Other resonances have been attributed to sounder-stimulated plasma instability and non-linear effects, eigenmodes of cylindrical electromagnetic plasma oscillations, and plasma memory processes. Data from the topside sounders of the International Satellites for Ionospheric Studies (ISIS) program played a major role in these interpretations. A data transformation and preservation effort at the Goddard Space Flight Center has produced digital ISIS topside ionograms and a metadata search program that has enabled some recent discoveries pertaining to the physics of these plasma resonances. For example, data records were obtained that enabled the long-standing question (several decades) of the origin of the plasma resonance at the fundamental electron cyclotron frequency to be explained [Muldrew, Radio Sci., 2006]. These data-search capabilities, and the science enabled by them, will be presented as a guide to desired data search capabilities to be included in the Virtual Wave Observatory (VWO).

  7. Global Daily Atmospheric State Profiles from the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Aumann, Hartmut H.; Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Chahine, Moustafa T.

    2008-01-01

    The Atmospheric Infrared Sounder (AIRS) is a hyperspectral infrared instrument on the EOS Aqua Spacecraft, launched on May 4, 2002. AIRS has 2378 infrared channels ranging from 3.7 (micro)m to 15.4 (micro)m and a 13.5 km footprint. AIRS, in conjunction with the Advanced Microwave Sounding Unit (AMSU), produces temperature profiles with 1K/km accuracy on a global scale, as well as water vapor profiles, clouds, dust and trace gas amounts for CO2, CO, SO2, O3 and CH4.[1] AIRS data are used for weather forecasting and studies of global climate change. The AIRS is a 'facility' instrument developed by NASA as an experimental demonstration of advanced technology for remote sensing and the benefits of high resolution infrared spectra to science investigations.

  8. A case study of a density structure over a vertical magnetic field region in the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Duru, F.; Gurnett, D. A.; Diéval, C.; Morgan, D. D.; Pisa, D.; Lundin, R.

    2016-05-01

    One of the discoveries made by the radar sounder on the Mars Express spacecraft is the existence of magnetically controlled structures in the ionosphere of Mars, which result in bulges in the ionospheric electron density contours. These bulges lead in turn to oblique echoes, which show up as hyperbola-shaped features in the echograms. A hyperbola-shaped feature observed over an isolated region of strong crustal magnetic field is associated with a plasma cavity in the upper ionosphere and a corresponding density enhancement in the lower levels of the ionosphere. We suggest that along open magnetic field lines, the solar wind electrons are accelerated downward and the ionospheric ions are accelerated upward in a manner similar to the field line-driven auroral acceleration at Earth. This heating due to precipitating electrons may cause an increase in the scale height and may drive a loss of ionospheric plasma at high altitudes.

  9. LAWS (Laser Atmospheric Wind Sounder) earth observing system

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Wind profiles can be measured from space using current technology. These wind profiles are essential for answering many of the interdisciplinary scientific questions to be addressed by EOS, the Earth Observing System. This report provides guidance for the development of a spaceborne wind sounder, the Laser Atmospheric Wind Sounder (LAWS), discussing the current state of the technology and reviewing the scientific rationale for the instrument. Whether obtained globally from the EOS polar platform or in the tropics and subtropics from the Space Station, wind profiles from space will provide essential information for advancing the skill of numerical weather prediction, furthering knowledge of large-scale atmospheric circulation and climate dynamics, and improving understanding of the global biogeochemical and hydrologic cycles. The LAWS Instrument Panel recommends that it be given high priority for new instrument development because of the pressing scientific need and the availability of the necessary technology. LAWS is to measure wind profiles with an accuracy of a few meters per second and to sample at intervals of 100 km horizontally for layers km thick.

  10. A review of ionospheric effects on Earth-space propagation

    NASA Technical Reports Server (NTRS)

    Klobuchar, J. A.

    1984-01-01

    A short description is given of each ionospheric total electron content (TEC) effect upon radio waves, along with a representative value of the magnitude of each of these effects under normal ionospheric conditions. A discussion is given of the important characteristics of average ionospheric TEC behavior and the temporal and spatial variability of TEC. Radio waves undergo several effects when they pass through the Earth's ionosphere. One of the most important of these effects is a retardation, or group delay, on the modulation or information carried on the radio wave that is due to its encounter with the free, thermal electrons in the Earth's ionosphere. Other effects the ionosphere has on radio waves include: radio frequency (RF) carrier phase advance; Doppler shift of the RF carrier of the radio wave; Faraday rotation of the plane of polarization of linearly polarized waves; angular refraction or bending of the radio wave path as it travels through the ionosphere; and amplitude and phase scintillations.

  11. Mars Ionospheric Response to Solar Wind Variability

    NASA Astrophysics Data System (ADS)

    Opgenoorth, H. J.; Edberg, N.; Lester, M.; Williams, A.; Fränz, M.; Witasse, O.; Duru, F.; Morgan, D.

    2011-10-01

    At planets with induced magnetospheres the coupling between the ionosphere, the small draped magnetosphere and the solar wind is in a way much more direct than at Earth. On the other hand it is also much more complicated as the magnetosphere itself is created and in its total shape and strength dynamically depending on the prevailing Solar wind conditions. In early 2010 Mars was located behind Earth in the Solar wind. In this study we have utilized coordinated data from multiple near-Earth spacecraft (Stereo, ACE, Cluster, and even Earth groundbased data) to evaluate what kind of Solar wind disturbances have passed by Earth and might hit Mars consecutively (and when). We use plasma data from the ESA Mars- Express mission (mainly from the ASPERA particle instrument and the MARSIS topside ionospheric sounder) to investigate what kind of ionospheric and magnetospheric response is triggered at Mars in response to Solar wind variability in the magnetic field, density and velocity for a number of isolated events in March and April 2010.

  12. Ionospheric and satellite observations for studying the dynamic behavior of typhoons and the detection of severe storms and tsunamis

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Smith, R. E.

    1978-01-01

    Atmospheric acoustic-gravity waves associated with severe thunderstorms, tornadoes, typhoons (hurricanes) and tsunamis can be studied through the coupling between the ionosphere and the troposphere. Reverse ray tracing computations of acoustic-gravity waves observed by an ionospheric Doppler sounder array show that wave sources are in the nearby storm systems and that the waves are excited prior to the storms. Results show that ionospheric observations, together with satellite observations, can contribute to the understanding of the dynamical behavior of typhoons, severe storms and tsunamis.

  13. VAS demonstration: (VISSR Atmospheric Sounder) description

    NASA Technical Reports Server (NTRS)

    Montgomery, H. E.; Uccellini, L. W.

    1985-01-01

    The VAS Demonstration (VISSR Atmospheric Sounder) is a project designed to evaluate the VAS instrument as a remote sensor of the Earth's atmosphere and surface. This report describes the instrument and ground processing system, the instrument performance, the valiation as a temperature and moisture profiler compared with ground truth and other satellites, and assesses its performance as a valuable meteorological tool. The report also addresses the availability of data for scientific research.

  14. Space View Issues for Hyperspectral Sounders

    NASA Technical Reports Server (NTRS)

    Manning, Evan M.; Aumann, Hartmut H.; Broberg, Steven E.

    2013-01-01

    The expectation for climate quality measurements from hyperspectral sounders is absolute calibration accuracy at the 100 mK level and stability at the < 40 mK/decade level. The Atmospheric InfraRed Sounder (AIRS)1, Cross-track Infrared Sounder (CrIS), and Infrared Atmospheric Sounding Interferometer (IASI) hyperspectral sounders currently in orbit have been shown to agree well over most of their brightness temperature range. Some larger discrepancies are seen, however, at the coldest scene temperatures, such as those seen in Antarctic winter and deep convective clouds. A key limiting factor for the calibrated scene radiance accuracy for cold scenes is how well the effective radiance of the cold space view pertains to the scene views. The space view signal is composed of external sources and instrument thermal emission at about 270 K from the scan mirror, external baffles, etc. Any difference in any of these contributions between space views and scene views will impact the absolute calibration accuracy, and the impact can be critical for cold scenes. Any change over time in these will show up as an apparent trend in calibrated radiances. We use AIRS data to investigate the validity of the space view assumption in view of the 100 mK accuracy and 40 mK/decade trend expectations. We show that the space views used for the cold calibration point for AIRS v5 Level-1B products meet these standards except under special circumstances and that AIRS v6 Level-1B products will meet them under all circumstances. This analysis also shows the value of having multiple distinct space views to give operational redundancy and analytic data, and that reaching climate quality requires continuing monitoring of aging instruments and adjustment of calibration.

  15. Rocket/Nimbus Sounder Comparison (RNSC)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The experimental results for radiance and temperature differences in the Wallops Island comparisons indicate that the differences between satellite and rocket systems are of the same order of magnitude as the differences among the various satellite and rocket sounders. The Arcasondes produced usable data to about 50 km, while the Datasondes require design modification. The SIRS and IRIS soundings provided usable data to 30 mb; extension of these soundings was also investigated.

  16. Radiometric consistency assessment of hyperspectral infrared sounders

    NASA Astrophysics Data System (ADS)

    Wang, L.; Han, Y.; Jin, X.; Chen, Y.; Tremblay, D. A.

    2015-07-01

    The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared (IR) hyperspectral radiance benchmark datasets for both inter-calibration and climate-related studies. In this study, the CrIS radiance measurements on Suomi National Polar-orbiting Partnership (SNPP) satellite are directly compared with IASI on MetOp-A and -B at the finest spectral scale and with AIRS on Aqua in 25 selected spectral regions through one year of simultaneous nadir overpass (SNO) observations to evaluate radiometric consistency of these four hyperspectral IR sounders. The spectra from different sounders are paired together through strict spatial and temporal collocation. The uniform scenes are selected by examining the collocated Visible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightness temperature (BT) differences are then calculated by converting the spectra onto common spectral grids. The results indicate that CrIS agrees well with IASI on MetOp-A and IASI on MetOp-B at the longwave IR (LWIR) and middle-wave IR (MWIR) bands with 0.1-0.2 K differences. There are no apparent scene-dependent patterns for BT differences between CrIS and IASI for individual spectral channels. CrIS and AIRS are compared at the 25 spectral regions for both Polar and Tropical SNOs. The combined global SNO datasets indicate that, the CrIS-AIRS BT differences are less than or around 0.1 K among 21 of 25 comparison spectral regions and they range from 0.15 to 0.21 K in the remaining 4 spectral regions. CrIS-AIRS BT differences in some comparison spectral regions show weak scene-dependent features.

  17. Radiometric consistency assessment of hyperspectral infrared sounders

    NASA Astrophysics Data System (ADS)

    Wang, L.; Han, Y.; Jin, X.; Chen, Y.; Tremblay, D. A.

    2015-11-01

    The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared (IR) hyperspectral radiance benchmark data sets for both intercalibration and climate-related studies. In this study, the CrIS radiance measurements on Suomi National Polar-orbiting Partnership (SNPP) satellite are directly compared with IASI on MetOp-A and MetOp-B at the finest spectral scale and with AIRS on Aqua in 25 selected spectral regions through simultaneous nadir overpass (SNO) observations in 2013, to evaluate radiometric consistency of these four hyperspectral IR sounders. The spectra from different sounders are paired together through strict spatial and temporal collocation. The uniform scenes are selected by examining the collocated Visible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightness temperature (BT) differences are then calculated by converting the spectra onto common spectral grids. The results indicate that CrIS agrees well with IASI on MetOp-A and IASI on MetOp-B at the long-wave IR (LWIR) and middle-wave IR (MWIR) bands with 0.1-0.2 K differences. There are no apparent scene-dependent patterns for BT differences between CrIS and IASI for individual spectral channels. CrIS and AIRS are compared at the 25 spectral regions for both polar and tropical SNOs. The combined global SNO data sets indicate that the CrIS-AIRS BT differences are less than or around 0.1 K among 21 of 25 spectral regions and they range from 0.15 to 0.21 K in the remaining four spectral regions. CrIS-AIRS BT differences in some comparison spectral regions show weak scene-dependent features.

  18. Soviet ionospheric modification research

    SciTech Connect

    Duncan, L.M.; Carlson, H.C.; Djuth, F.T.; Fejer, J.A.; Gerson, N.C.; Hagfors, T.; Newman, D.B. Jr.; Showen, R.L.

    1988-07-01

    Soviet published literature in ionospheric modification research by high-power radio waves is assessed, including an evaluation of its impact on and applications to future remote-sensing and telecommunications systems. This assessment is organized to place equal emphasis on basic research activities, designed to investigate both the natural geophysical environment and fundamental plasma physics; advanced research programs, such as those studying artificial ionization processes and oblique high-power radio propagation and practical system applications and operational limitations addressed by this research. The assessment indicates that the Soviet Union sustains high-quality theoretical and experimental research programs in ionospheric modification, with a breadth and level of effort greatly exceeding comparable Western programs. Soviet theoretical research tends to be analytical and intuitive, as compared to the Western emphasis on numerical simulation techniques. The Soviet experimental approach is less exploratory, designed principally to confirm theoretical predictions. Although limited by inferior diagnostic capabilities, Soviet experimental facilities are more numerous, operate on a more regular basis, and transmit radio wave powers exceeding those os Western facilities. Because of its broad scope of activity, the Soviet Union is better poised to quickly exploit new technologies and system applications as they are developed. This panel has identified several key areas of Soviet research activity and emerging technology that may offer long-term opportunities for remote-sensing and telecommunications advantages. However, we have found no results that suggest imminent breakthrough discoveries in these fields.

  19. Photochemistry of planetary ionospheres

    NASA Technical Reports Server (NTRS)

    Nagy, Andrew F.

    1987-01-01

    The dominant photochemical reactions taking place in the ionospheres of Venus, Saturn, and Comet P/Halley are presented. It is shown that the differences in the ionospheres of these celestial bodies result from the different chemistry, energetics, and dynamics of the respective atmospheres. The role of photochemistry in the formation of the individual ionospheres is discussed.

  20. Integrated Verification Experiment data collected as part of the Los Alamos National Laboratory`s Source Region Program. Appendix D: Ionospheric measurements for IVEs

    SciTech Connect

    Fitzgerald, T.J.; Carlos, R.C.; Argo, P.E.

    1993-01-21

    As part of the integrated verification experiment (IVE), we deployed a network of hf ionospheric sounders to detect the effects of acoustic waves generated by surface ground motion following underground nuclear tests at the Nevada Test Site. The network sampled up to four geographic locations in the ionosphere from almost directly overhead of the surface ground zero out to a horizontal range of 60 km. We present sample results for four of the IVEs: Misty Echo, Texarkana, Mineral Quarry, and Bexar.

  1. Ionospheric redistribution during geomagnetic storms.

    PubMed

    Immel, T J; Mannucci, A J

    2013-12-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<-100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3-6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

  2. Coupling of ionosphere and troposphere during the occurrence of isolated tornadoes on November 20, 1973

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Phan, T.; Smith, R. E.

    1979-01-01

    The paper examines the coupling between the ionosphere and the troposphere during time periods with isolated tornadoes on the stormy day of November 20, 1973. Observations are made with a high-frequency CW Doppler array system, in which radio receivers located at a central site monitored signals transmitted from three independent remote sites on three sets of frequencies (4.0125, 4.759, 5.734 MHz) and reflected off the ionosphere approximately halfway between the transmitter and receiver sites. It is shown that the sources of the gravity waves associated with tornadoes are always on the squall lines and near the tornado touchdown locations, and that analyses of ionospheric Doppler sounder observations of medium-scale gravity waves can contribute to the understanding of the coupling between the ionosphere and the troposphere during periods of severe storm activity.

  3. Mars ionospheric response to solar wind variability

    NASA Astrophysics Data System (ADS)

    Opgenoorth, H. J.; Andrews, D. J.; Fränz, M.; Lester, M.; Edberg, N. J. T.; Morgan, D.; Duru, F.; Witasse, O.; Williams, A. O.

    2013-10-01

    planets with induced magnetospheres, the coupling between the ionosphere, the weak draped magnetosphere, and the solar wind is very direct in comparison to Earth. The weak induced magnetosphere itself is created by the prevailing Solar wind conditions and therefore in its shape and strength dynamically depending on it. In early 2010, Mars was located behind Earth in the Solar wind; thus, we can use coordinated data from multiple near-Earth spacecraft (Stereo, Wind) to evaluate what kind of Solar wind disturbances have passed by Earth and might consecutively hit Mars, and when. We employ plasma data from the ESA Mars-Express mission, the ASPERA-3 particle instrument, and the MARSIS Active Ionospheric Sounder (AIS) to investigate, for a number of isolated events in March and April 2010, how the ionosphere and the induced magnetosphere at Mars develop and decay in response to Solar wind variability in the magnetic field, density, and velocity. In a dedicated campaign mode, we use frequent long-duration MARSIS AIS operations for several consecutive orbits, to monitor for the first time the long-term development of the Martian plasma environment during solar wind disturbances. We find that the magnetosphere and ionosphere of Mars can become considerably compressed by solar wind dynamic pressure variations, which usually are also associated with changes in the magnetic draping of the interplanetary magnetic field around the planet. These are typically associated with corotating interaction regions and coronal mass ejections, and can last for several days. During such episodes of compression, we see signatures of increased plasma transport over the terminator and enhanced ion outflow from the upper atmosphere.

  4. Propagation studies using a theoretical ionosphere model

    NASA Technical Reports Server (NTRS)

    Lee, M.

    1973-01-01

    The mid-latitude ionospheric and neutral atmospheric models are coupled with an advanced three dimensional ray tracing program to see what success would be obtained in predicting the wave propagation conditions and to study to what extent the use of theoretical ionospheric models is practical. The Penn State MK 1 ionospheric model, the Mitra-Rowe D region model, and the Groves' neutral atmospheric model are used throughout this work to represent the real electron densities and collision frequencies. The Faraday rotation and differential Doppler velocities from satellites, the propagation modes for long distance high frequency propagation, the group delays for each mode, the ionospheric absorption, and the spatial loss are all predicted.

  5. Preliminary validation of the refractivity from the new radio occultation sounder GNOS/FY-3C

    NASA Astrophysics Data System (ADS)

    Liao, Mi; Zhang, Peng; Yang, Guang-Lin; Bi, Yan-Meng; Liu, Yan; Bai, Wei-Hua; Meng, Xiang-Guang; Du, Qi-Fei; Sun, Yue-Qiang

    2016-03-01

    As a new member of the space-based radio occultation sounders, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on Fengyun-3C (FY-3C) has been carrying out atmospheric sounding since 23 September 2013. GNOS takes approximately 800 daily measurements using GPS (Global Positioning System) and Chinese BDS (BeiDou navigation satellite) signals. In this work, the atmospheric refractivity profiles from GNOS were compared with the ones obtained from the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis. The mean bias of the refractivity obtained through GNOS GPS (BDS) was found to be approximately -0.09 % (-0.04 %) from the near surface to up to 46 km. While the average standard deviation was approximately 1.81 % (1.26 %), it was as low as 0.75 % (0.53 %) in the range of 5-25 km, where best sounding results are usually achieved. Further, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and MetOp/ GRAS (GNSS Receiver for Atmospheric Sounding) radio occultation data were compared with the ECMWF reanalysis; the results thus obtained could be used as reference data for GNOS. Our results showed that GNOS/FY-3C meets the design requirements in terms of accuracy and precision of the sounder. It possesses a sounding capability similar to COSMIC and MetOp/GRAS in the vertical range of 0-30 km, though it needs further improvement above 30 km. Overall, it provides a new data source for the global numerical weather prediction (NWP) community.

  6. Representation of the Auroral and Polar Ionosphere in the International Reference Ionosphere (IRI)

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter; Reinisch, Bodo

    2013-01-01

    This issue of Advances in Space Research presents a selection of papers that document the progress in developing and improving the International Reference Ionosphere (IRI), a widely used standard for the parameters that describe the Earths ionosphere. The core set of papers was presented during the 2010 General Assembly of the Committee on Space Research in Bremen, Germany in a session that focused on the representation of the auroral and polar ionosphere in the IRI model. In addition, papers were solicited and submitted from the scientific community in a general call for appropriate papers.

  7. Preliminary validation of refractivity from a new radio occultation sounder GNOS/FY-3C

    NASA Astrophysics Data System (ADS)

    Liao, M.; Zhang, P.; Yang, G. L.; Bi, Y. M.; Liu, Y.; Bai, W. H.; Meng, X. G.; Du, Q. F.; Sun, Y. Q.

    2015-09-01

    As a new member of space-based radio occultation sounder, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on FY-3C has been carrying out the atmospheric sounding since 23 September 2013. GNOS takes a daily measurement up to 800 times with GPS (Global Position System) and Chinese BDS (BeiDou navigation satellite) signals. The refractivity profiles from GNOS are compared with the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) analyses in this paper. Bias and standard deviation have being calculated as the function of altitude. The mean bias is about 0.2 % from the near surface to 35 km. The average standard deviation is within 2 % while it is down to about 1 % in the range 5-30 km where best soundings are usually made. To evaluate the performance of GNOS, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and GRAS/METOP-A (GNSS Receiver for Atmospheric Sounding) data are also compared to ECMWF analyses as the reference. The results show that GNOS/FY-3C meets the requirements of the design well. It possesses a sounding capability similar to COSMIC and GRAS in the vertical range of 0-30 km, though it needs improvement in higher altitude. Generally, it provides a new data source for global NWP (numerical weather prediction) community.

  8. Design and Evaluation of Compact Antennae for Ionospheric Sounding

    NASA Astrophysics Data System (ADS)

    Erjavec, T. J.; Vierinen, J.

    2014-12-01

    Compact high frequency (HF) antennas are crucial for enabling the use of HF radar sounding for ionospheric remote sensing using a dense network of sounders. Current ionosonde antennas are large and expensive. In this study, we investigate two compact HF antenna designs through modeling and prototypes: a folded resistively loaded dipole, and a capacitively tuned small magnetic loop. Both antennas were modeled using FEKO to investigate antenna efficiency and beam patterns. The folded dipole was bought off the shelf, while the compact magnetic loop prototype was built in house. In this study, we present both modeling and measurements of the antenna characteristics. We also present the first ionospheric soundings obtained using the prototype antennas.

  9. IONOSATS - ionospheric satellite cluster

    NASA Astrophysics Data System (ADS)

    Ivchenko, V.; Korepanov, V.; Lizunov, G.; Yampolsky, Yu.

    The IONOSATS project is proposed by National Space Agency of Ukraine for First European Space Program as well as for Space Weather SW Program as a part of GMES As it commonly accepted Space Weather means the changes of the conditions on the Sun in solar wind magnetosphere and ionosphere which may affect the operation and reliability of on-board and ground technological systems and threaten human health In this chain ionosphere is specific and integral part of SW formation Moreover namely in the ionosphere main part of the energy absorption of Sun-activated sporadic corpuscular and radiation fluxes takes places Short-wave part of solar flares radiation ultraviolet and roentgen dissipates mostly at ionospheric regions E and D heights triggering ionospheric storms The corpuscular fluxes energy absorption occurs in the polar parts of the ionosphere as a result in the auroral regions the current system of aurora causes the neutral atmosphere heating at the E and F regions heights In its turn this produces generation of a set of plasma instabilities including equator-spread large-scale ionospheric disturbances and electromagnetic waves emissions In other words the excitation of ionosphere by falling corpuscular and radiation fluxes produces its luminescence in wide frequency band - from radio waves till ultraviolet - and by this ionosphere works as an efficient screen or SW indicator The proposed project goal is long-term spatial-temporal monitoring of main field and plasma parameters of ionosphere with aim to further develop fundamental conceptions

  10. View to the south with the Two Sounder Antennas on ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the south with the Two Sounder Antennas on the left - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  11. Radar sounder performances for ESA JUICE mission

    NASA Astrophysics Data System (ADS)

    Berquin, Y. P.; Kofman, W. W.; Heggy, E.; Hérique, A.

    2012-12-01

    The Jupiter Icy moons Explorer (JUICE) is the first Large-class mission chosen as part of ESA's Cosmic Vision 2015-2025 program. The mission will study Jovian icy moons Ganymede and Europa as potential habitats for life, addressing two key themes of Cosmic Vision namely the conditions for planet formation and the emergence of life, and the Solar System interactions. The radar sounder instrument on this mission will have great potential to address specific science questions such as the presence of subsurface liquid water and ice shell geophysical structures. One major constraint for radar sounding is the roughness of the planetary surface. The work presented will focus on the characterization of Ganymede's surface topography to better understand its surface properties from a radar point of view. These results should help to put constraints on the design of JUICE's radar sounder. We use topographic data derived from the Voyager and Galileo missions images to try to characterize the surface structure and to quantify its geometry (in terms of slopes and RMS heights mainly). This study will help us evaluating the radar budget in a statistical approach. In addition, deterministic simulations of surface radar echoes conducted on synthetic surfaces -extrapolated from Digital Elevation Models- will be presented to better assess radar sounding performances.

  12. Science Highlights and Lessons Learned from the Atmospheric Infrared Sounder (AIRS)

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Fetzer, Eric J.; Suda, Jarrod; Licata, Steve

    2011-01-01

    The Atmospheric Infrared Sounder (AIRS) and companion instrument, the Advanced Microwave Sounding Unit (AMSU) on the NASA Earth Observing System Aqua spacecraft are facility instruments designed to support measurements of atmospheric temperature, water vapor and a wide range of atmospheric constituents in support of weather forecasting and scientific research in climate and atmospheric chemistry. This paper is an update to the science highlights from a paper by the authors released last year and also looks back at the lessons learned and future needs of the scientific community. These lessons not only include requirements on the measurements, but scientific shortfalls as well. Results from the NASA Science Community Workshop in IR and MW Sounders relating to AIRS and AMSU requirements and concerns are covered and reflect much of what has been learned and what is needed for future atmospheric sounding from Low Earth Orbit.

  13. Fluctuation of the Martian ionosphere observed by Mars Express ionospheric sounding

    NASA Astrophysics Data System (ADS)

    Morgan, D. D.; Gurnett, D. A.; Duru, F.; Akalin, F.; Brain, D. A.

    2009-12-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), on board the ESA spacecraft Mars Express, in its Active Ionospheric Sounding mode, produces ionograms that enable us to compute electron density profiles of the Martian ionosphere over a wide range of day-side solar zenith angles and planetary longitudes and latitudes at a maximum resolution of 7.543 s. An electron density profile contains the values of the ionospheric peak electron density and its corresponding altitude. In order to analyze the state of motion of the Martian ionosphere, we have computed the standard deviation of these two quantities for four-minute intervals spanning the time between 14 August 2005 and 19 April 2009 corresponding to 473 orbits of Mars Express between orbits 2032 and 6795. Our analysis shows that fluctuation of the Martian ionosphere, as indicated by both the peak electron density and the peak altitude, increases at solar zenith angles greater than 60° and that this increase is strongest in regions of high remanent magnetic field. Use of the MGS solar-wind magnetic-field-draping direction proxy indicates that these fluctuations are strongest when remanent and solar-wind-borne fields are oppositely directed. These measurements open the possibility that near-terminator fluctuation in the Martian ionosphere is related to magnetic reconnection coupled with bulk outflows from the Martian atmosphere.

  14. Preliminary investigation of ionospheric modifucation using oblique-incidence high-power h-f (high-frequency) radio waves. Technical report

    SciTech Connect

    Sales, G.S.; Reinisch, B.W.; Dozois, C.G.

    1986-09-01

    A special experiment was carried out using a high-powered transmitter and a high-gain rhombic antenna to heat the ionosphere at a distance of 1300 km from the transmitter. A Digisonde ionospheric sounder was located at the midpoint to sense any changes that might occur in the ionosphere at the heating cycle period of ten minutes. The measured phase data were processed using spectrum analysis in an attempt to detect this ten-minute period. The results are not conclusive, but there is some indication that the heating period was detected only during the nighttime in agreement with theoretical prediction.

  15. Regional Assimilation of NASA Atmospheric Infrared Sounder (AIRS) Data

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung; Lapenta, William; Jediovec, Gary J.; McCarty, William; Mecikalski, John R.

    2004-01-01

    The NASA Short-term Prediction Research and Transition (SPORT) Center seeks to accelerate the infusion of NASA Earth Science Enterprise (ESE) observations, data assimilation and modeling research into NW S forecast operations and decision-making. The Atmospheric Infrared Sounder (AIRS), is expected to advance climate research and weather prediction into the 21 st century. It is one of six instruments onboard Aqua, a satellite that is part of NASA s Earth Observing System. AIRS, along with two partner microwave sounding instruments, represents the most advanced atmospheric sounding system ever deployed in space. The system is capable of measuring the atmospheric temperature in the troposphere with radiosonde accuracies of 1 K over 1 km-thick layers under both clear and cloudy conditions, while the accuracy of the derived moisture profiles will exceed that obtained by radiosondes. It is imperative that the scientific community is prepared to take full advantage of next-generation satellite data that will become available within the next decade. The purpose of this paper is to describe a procedure designed to optimally assimilate AIRS data at high spatial resolution over both land and ocean. The assimilation system used in this study is the Local Analysis and Prediction System (LAPS) developed at the Forecast System Laboratory used extensively around the globe. Results will focus on quality control issues associated with AIRS, optimal assimilation strategies, and the impact of the AIRS data on subsequent numerical forecasts at 12 km produced by the next generation Weather Research and Forecast (WRF) model.

  16. Preface: International Reference Ionosphere - Progress in Ionospheric Modelling

    NASA Technical Reports Server (NTRS)

    Bilitza Dieter; Reinisch, Bodo

    2010-01-01

    The international reference ionosphere (lRI) is the internationally recommended empirical model for the specification of ionospheric parameters supported by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) and recognized by the International Standardization Organization (ISO). IRI is being continually improved by a team of international experts as new data become available and better models are being developed. This issue chronicles the latest phase of model updates as reported during two IRI-related meetings. The first was a special session during the Scientific Assembly of the Committee of Space Research (COSPAR) in Montreal, Canada in July 2008 and the second was an IRI Task Force Activity at the US Air Force Academy in Colorado Springs in May 2009. This work led to several improvements and additions of the model which will be included in the next version, IRI-201O. The issue is divided into three sections focusing on the improvements made in the topside ionosphere, the F-peak, and the lower ionosphere, respectively. This issue would not have been possible without the reviewing efforts of many individuals. Each paper was reviewed by two referees. We thankfully acknowledge the contribution to this issue made by the following reviewers: Jacob Adeniyi, David Altadill, Eduardo Araujo, Feza Arikan, Dieter Bilitza, Jilijana Cander, Bela Fejer, Tamara Gulyaeva, Manuel Hermindez-Pajares, Ivan Kutiev, John MacDougal, Leo McNamara, Bruno Nava, Olivier Obrou, Elijah Oyeyemi, Vadym Paznukhov, Bodo Reinisch, John Retterer, Phil Richards, Gary Sales, J.H. Sastri, Ludger Scherliess, Iwona Stanislavska, Stamir Stankov, Shin-Yi Su, Manlian Zhang, Y ongliang Zhang, and Irina Zakharenkova. We are grateful to Peggy Ann Shea for her final review and guidance as the editor-in-chief for special issues of Advances in Space Research. We thank the authors for their timely submission and their quick response to the reviewer comments and humbly

  17. RAWS: The spaceborne radar wind sounder

    NASA Technical Reports Server (NTRS)

    Moore, Richard K.

    1991-01-01

    The concept of the Radar Wind Sounder (RAWS) is discussed. The goals of the RAWS is to estimate the following three qualities: the echo power, to determine rain rate and surface wind velocity; the mean Doppler frequency, to determine the wind velocity in hydrometers; and the spread of the Doppler frequency, to determine the turbulent spread of the wind velocity. Researchers made significant progress during the first year. The feasibility of the concept seems certain. Studies indicate that a reasonably sized system can measure in the presence of ice clouds and dense water clouds. No sensitivity problems exist in rainy environments. More research is needed on the application of the radar to the measurement of rain rates and winds at the sea surface.

  18. RAWS: The spaceborne radar wind sounder

    NASA Astrophysics Data System (ADS)

    Moore, Richard K.

    1991-09-01

    The concept of the Radar Wind Sounder (RAWS) is discussed. The goals of the RAWS is to estimate the following three qualities: the echo power, to determine rain rate and surface wind velocity; the mean Doppler frequency, to determine the wind velocity in hydrometers; and the spread of the Doppler frequency, to determine the turbulent spread of the wind velocity. Researchers made significant progress during the first year. The feasibility of the concept seems certain. Studies indicate that a reasonably sized system can measure in the presence of ice clouds and dense water clouds. No sensitivity problems exist in rainy environments. More research is needed on the application of the radar to the measurement of rain rates and winds at the sea surface.

  19. EOS Laser Atmosphere Wind Sounder (LAWS) investigation

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In this final report, the set of tasks that evolved from the Laser Atmosphere Wind Sounder (LAWS) Science Team are reviewed, the major accomplishments are summarized, and a complete set of resulting references provided. The tasks included preparation of a plan for the LAWS Algorithm Development and Evolution Laboratory (LADEL); participation in the preparation of a joint CNES/NASA proposal to build a space-based DWL; involvement in the Global Backscatter Experiments (GLOBE); evaluation of several DWL concepts including 'Quick-LAWS', SPNDL and several direct detection technologies; and an extensive series of system trade studies and Observing System Simulation Experiments (OSSE's). In this report, some of the key accomplishments are briefly summarized with reference to interim reports, special reports, conference/workshop presentations, and publications.

  20. Assimilation of the Microwave Limb Sounder Radiances

    NASA Technical Reports Server (NTRS)

    Wargan, K.; Read, W.; Livesey, N.; Wagner, P.; Nguyen. H.; Pawson, S.

    2012-01-01

    It has been shown that the assimilation of limb-sounder data can significantly improve the representation of ozone in NASA's GEOS Data Assimilation Systems (GEOS-DAS), particularly in the stratosphere. The studies conducted so far utilized retrieved data from the MIPAS, POAM, ILAS and EOS Microwave Limb Sounder (EOS MLS) instruments. Direct assimilation of the radiance data can be seen as the natural next step to those studies. The motivation behind working with radiances is twofold. First, retrieval algorithms use a priori data which are either climatological or are obtained from previous analyses. This introduces additional uncertainty and, in some cases, may lead to "self-contamination"- when the a priori is taken from the same assimilation system in which subsequently ingests the retrieved observations. Second, radiances can be available in near real time thus providing an opportunity for operational assimilation, which could help improve the use of infrared radiance instruments from operational satellite instruments. In this presentation we summarize our ongoing work on an implementation of the assimilation of EOS MLS radiances into the GEOS-5 DAS. This work focuses on assimilation of band 7 brightness temperatures which are sensitive to ozone. Our implementation uses the MLS Callable Forward Model developed by the MLS team at NASA JPL as the observation operator. We will describe our approach and recent results which are not yet final. In particular, we will demonstrate that this approach has a potential to improve the vertical structure of ozone in the lower tropical stratosphere as compared with the retrieved MLS product. We will discuss the computational efficiency of this implementation.

  1. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<−100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow. PMID:26167429

  2. First Data from Mars Climate Sounder

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Mars Climate Sounder, an instrument on NASA's Mars Reconnaissance Orbiter designed to monitor daily changes in the global atmosphere of Mars, made its first observations of Mars on March 24, 2006.

    These tests were conducted to demonstrate that the instrument could, if needed, support the mission's aerobraking maneuvers (dips into the atmosphere to change the shape of the orbit) by providing hemisphere-scale coverage of atmospheric activity. The instrument scanned nine arrays of detectors four times across the entire disc of the planet, including the north pole, from an altitude of about 45,000 kilometers (28,000 miles). This is about 150 times farther away than the spacecraft will be during its main science phase. At this great range, the planet appears only 40 pixels wide, as suggested by the pixilation of the images. However, this is sufficient to identify regional dust storms in the lower atmosphere. Regional dust storms could perturb atmospheric densities at the higher altitudes (about 100 kilometers or 60 miles) where the orbiter will conduct more than 500 aerobraking passes during the next six months. Such storms are rare in the current season on Mars, early northern spring, and no large storms are present as the orbiter prepares for the start of aerobraking.

    Each of the Mars Climate Sounder's arrays looks in a different wavelength band, and three of the resulting images are shown here. The view on the left is from data collected in a broad spectral band (wavelengths of 0.3 microns to 3 microns) for reflected sunlight. The view in the center is from data collected in the 12-micron thermal-infrared band. This band was chosen to sense infrared radiation from the surface when the atmosphere is clear and from dust clouds when it is not. The view on the right is from data collected at 15 microns, a longer-wavelength band still in the thermal-infrared part of the spectrum. At this wavelength, carbon dioxide, the main ingredient in Mars

  3. Saturn ionosphere - Theoretical interpretation

    NASA Astrophysics Data System (ADS)

    Atreya, S. K.; Waite, J. H.

    1981-08-01

    Voyager 1 high latitude and Pioneer 11 equatorial ionospheric structure indicate a solar EUV-controlled ionosphere with a possible molecular ion in the topside. Vibrationally excited H2 in the high latitudes may be an important loss mechanism. Dynamical effects are expected to be important for determining the peak density and its location.

  4. Magnetosphere-ionosphere interactions

    NASA Technical Reports Server (NTRS)

    Vondrak, R. R.; Chiu, Y. T.; Evans, D. S.; Patterson, V. G.; Romick, G. J.; Stasiewicz, K.

    1979-01-01

    The present understanding of magnetosphere ionosphere interactions is described, and present and future predictive capabilities are assessed. Ionospheric features directly coupled to the magnetosphere to a significant degree are considered, with emphasis given to those phenomena of major interest to forecasters and users.

  5. International reference ionosphere 1990

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter; Rawer, K.; Bossy, L.; Kutiev, I.; Oyama, K.-I.; Leitinger, R.; Kazimirovsky, E.

    1990-01-01

    The International Reference Ionosphere 1990 (IRI-90) is described. IRI described monthly averages of the electron density, electron temperature, ion temperature, and ion composition in the altitude range from 50 to 1000 km for magnetically quiet conditions in the non-auroral ionosphere. The most important improvements and new developments are summarized.

  6. Estimation of volcanic ash refractive index from satellite infrared sounder data

    NASA Astrophysics Data System (ADS)

    Ishimoto, H.; Masuda, K.

    2014-12-01

    The properties of volcanic ash clouds (cloud height, optical depth, and effective radius of the particles) are planned to estimate from the data of the next Japanese geostationary meteorological satellite, Himawari 8/9. The volcanic ash algorithms, such as those proposed by NOAA/NESDIS and by EUMETSAT, are based on the infrared absorption properties of the ash particles, and the refractive index of a typical volcanic rock (i.e. andesite) has been used in the forward radiative transfer calculations. Because of a variety of the absorption properties for real volcanic ash particles at infrared wavelengths (9-13 micron), a large retrieval error may occur if the refractive index of the observed ash particles was different from that assumed in the retrieval algorithm. Satellite infrared sounder provides spectral information for the volcanic ash clouds. If we can estimate the refractive index of the ash particles from the infrared sounder data, a dataset of the optical properties for similar rock type of the volcanic ash can be prepared for the ash retrieval algorithms of geostationary/polar-orbiting satellites in advance. Furthermore, the estimated refractive index can be used for a diagnostic and a correction of the ash particle model in the retrieval algorithm within a period of the volcanic activities. In this work, optimal estimation of the volcanic ash parameters was conducted through the radiative transfer calculations for the window channels of the atmospheric infrared sounder (AIRS). The estimated refractive indices are proposed for the volcanic ash particles of some eruption events.

  7. Electrodynamics and plasma processes in the ionosphere

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1987-01-01

    The paper examines the advances achieved between 1983 and 1986 on understanding ionospheric electrodynamics and associated plasma processes, including an assessment of the roles of the E- and F-region neutral winds in providing the large-scale electric field in the ionosphere, as well as of the influence of electric fields of magnetospheric origin on the motion and distribution of plasma. Studies of the factors affecting the creation and evolution of plasma structure with many different scale sizes are discussed. Consideration is also given to the ground-based and in situ techniques used in these studies.

  8. Remote detection of the maximum altitude of equatorial ionospheric plasma bubbles

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1981-01-01

    Nearly 200 post-sunset low-altitude passes of the Alouette 2 and ISIS 1 satellites near the dip equator are studied in order to find the maximum ionospheric plasma bubble altitudes, which are determined by calculating the apex altitude of the magnetic field line passing through the satellite when it is immersed in a bubble. The calculations are made only upon the observation of conjugate hemisphere ionospheric echoes, which result from ducted HF sounder signals that are guided along field-aligned irregularities within the plasma depletion. The maximum bubble altitudes corresponding to the three longitude sectors centered on zero deg, 75 deg W, and 105 deg E, are found to often exceed 1000 km, but seldom 3000 km. The electron density depletions within these field-aligned bubbles, as measured at the point of satellite encounter with the topside ionosphere, are generally less than a factor of two but may exceed a factor of ten.

  9. The Atmospheric Infrared Sounder Version 6 Cloud Products

    NASA Technical Reports Server (NTRS)

    Kahn, B. H.; Irion, F. W.; Dang, V. T.; Manning, E. M.; Nasiri, S. L.; Naud, C. M.; Blaisdell, J. M.; Schreier, M. M..; Yue, Q.; Bowman, K. W.; Fetzer, E. J.; Hulley, G. C.; Liou, K. N.; Lubin, D.; Ou, S. C.; Susskind, J.; Takano, Y.; Tian, B.; Worden, J. R.

    2014-01-01

    The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter D(sub e), and ice cloud optical thickness (t) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of tau are found in the storm tracks and near convection in the tropics, while D(sub e) is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of tau is significantly larger than for the total cloud fraction, ice cloud frequency, and D(sub e), and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

  10. Middle Atmosphere Sounder and Thermal Emission Radiometer - Master

    NASA Astrophysics Data System (ADS)

    Mlynczak, M. G.; Scott, D. K.; Esplin, R. W.; Bailey, S. M.; Randall, C. E.

    2014-12-01

    The Middle Atmosphere Sounder and Thermal Emission Radiometer (MASTER) instrument is an advanced infrared limb-scanning instrument designed to measure the thermal structure, chemical composition, and energy balance from the stratosphere to the lower thermosphere. MASTER builds on NASA's long and successful heritage of infrared limb scanners including the LIMS, HIRDLS, and SABER instruments. MASTER has exceptional radiometric sensitivity with a more efficient, compact, and lightweight design. An updated focal plane enables critical new science in the areas of the carbon budget closure, geomagnetically-driven ozone destruction, and auroral energy deposition, while virtually eliminating out of band contributions via dual filtering. MASTER will continue the SABER-TIMED and EOS-Aura records of temperature, lower stratospheric water vapor, ozone, methane, and thermospheric cooling by nitric oxide and carbon dioxide. MASTER's size and mass are specifically designed to allow flexibility in the choice of small satellite buses and low cost launch vehicles. The expanded focal plane enables a choice of channels applicable to science objectives in NASA's Earth Science and Heliophysics enterprises. Due to the long and successful heritage the MASTER instrument is at an exceptionally high technology readiness level. No new technologies are required to build the MASTER flight instrument.

  11. Assessment of intercalibration methods for satellite microwave humidity sounders

    NASA Astrophysics Data System (ADS)

    John, Viju O.; Allan, Richard P.; Bell, William; Buehler, Stefan A.; Kottayil, Ajil

    2013-05-01

    Three methods for intercalibrating humidity sounding channels are compared to assess their merits and demerits. The methods use the following: (1) natural targets (Antarctica and tropical oceans), (2) zonal average brightness temperatures, and (3) simultaneous nadir overpasses (SNOs). Advanced Microwave Sounding Unit-B instruments onboard the polar-orbiting NOAA 15 and NOAA 16 satellites are used as examples. Antarctica is shown to be useful for identifying some of the instrument problems but less promising for intercalibrating humidity sounders due to the large diurnal variations there. Owing to smaller diurnal cycles over tropical oceans, these are found to be a good target for estimating intersatellite biases. Estimated biases are more resistant to diurnal differences when data from ascending and descending passes are combined. Biases estimated from zonal-averaged brightness temperatures show large seasonal and latitude dependence which could have resulted from diurnal cycle aliasing and scene-radiance dependence of the biases. This method may not be the best for channels with significant surface contributions. We have also tested the impact of clouds on the estimated biases and found that it is not significant, at least for tropical ocean estimates. Biases estimated from SNOs are the least influenced by diurnal cycle aliasing and cloud impacts. However, SNOs cover only relatively small part of the dynamic range of observed brightness temperatures.

  12. A Submillimeter Sounder for Measuring Martian Winds and Water

    NASA Astrophysics Data System (ADS)

    Tamppari, L. K.; Livesey, N. J.; Read, W. G.

    2016-10-01

    We review the scientific need for global vertically resolved observations of martian atmospheric winds, and show that a submillimeter limb sounder can provide such measurements, along with measurements of water vapor and other trace gases.

  13. Ionospheric Specifications for SAR Interferometry (ISSI)

    NASA Technical Reports Server (NTRS)

    Pi, Xiaoqing; Chapman, Bruce D; Freeman, Anthony; Szeliga, Walter; Buckley, Sean M.; Rosen, Paul A.; Lavalle, Marco

    2013-01-01

    The ISSI software package is designed to image the ionosphere from space by calibrating and processing polarimetric synthetic aperture radar (PolSAR) data collected from low Earth orbit satellites. Signals transmitted and received by a PolSAR are subject to the Faraday rotation effect as they traverse the magnetized ionosphere. The ISSI algorithms combine the horizontally and vertically polarized (with respect to the radar system) SAR signals to estimate Faraday rotation and ionospheric total electron content (TEC) with spatial resolutions of sub-kilometers to kilometers, and to derive radar system calibration parameters. The ISSI software package has been designed and developed to integrate the algorithms, process PolSAR data, and image as well as visualize the ionospheric measurements. A number of tests have been conducted using ISSI with PolSAR data collected from various latitude regions using the phase array-type L-band synthetic aperture radar (PALSAR) onboard Japan Aerospace Exploration Agency's Advanced Land Observing Satellite mission, and also with Global Positioning System data. These tests have demonstrated and validated SAR-derived ionospheric images and data correction algorithms.

  14. IONOSAT Ionospheric satellite cluster

    NASA Astrophysics Data System (ADS)

    Korepanov, V.; Lizunov, G.; Fedorov, O.; Yampolsky, Yu.; Ivchenko, V.

    2008-11-01

    The IONOSAT project (from IONOspheric SATellites) is proposed by National Space Agency of Ukraine for First European Space Program as a part of Space Weather (SW) Program. As it is commonly accepted, Space Weather means the changes of the conditions on the Sun, in solar wind, magnetosphere and ionosphere which may affect the operation and reliability of on-board and ground technological systems and threaten human health. In this chain ionosphere is specific and integral part of SW formation. Moreover, namely in the ionosphere main part of the energy absorption of Sun-activated sporadic corpuscular and radiation fluxes takes places. The excitation of ionosphere by falling fluxes produces its "luminescence" in wide frequency band - from ULF waves till ultraviolet - and by this ionosphere works as an efficient "screen" or SW indicator. A goal of the proposed project is long-term spatial-temporal monitoring of main field and plasma parameters of ionosphere with aim to further develop fundamental conceptions of solar-terrestrial connections physics, nowcasting and forecast of SW, and diagnostics of natural and technogenic hazards with the help of scientific payload installed on-board a cluster of 3 low-Earth orbit (LEO) microsatellites (tentative launch date - 2012 year). The state of the project proposal and realization plans are discussed.

  15. Extremely Low Ionospheric Peak Altitudes in the Polar-Hole Region

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Grebowsky, Joseph M.

    1999-01-01

    Vertical electron-density (N (sub e)) profiles, deduced from newly-available ISIS-II digital ionospheric topside-sounder data, are used to investigate the "polar-hole" region within the winter, nighttime polar cap ionosphere during solar minimum. The hole region is located around 0200 MLT near the poleward side of the auroral oval. Earlier investigations had revealed very low N (sub e) values in this region (down to 200/cu cm near 300 km). In the present study, such low N, values (approx. 100/cu cm) were only found near the ISIS (International Satellite for Ionospheric Study)-II altitude of 1400 km. The peak ionospheric concentration below the spacecraft remained fairly constant (approx. 10 (exp 5)/cu cm across the hole region but the altitude of the peak dropped dramatically. This peak dropped, surprisingly, to the vicinity of 100 km. These observations suggest that the earlier satellite in situ measurements, interpreted as deep holes in the ionospheric F-region concentration, could have been made during conditions of an extreme decrease in the altitude of the ionospheric N (sub e) peak. The observations, in combination with other data, indicate that the absence of an F-layer peak may be a frequent occurrence at high latitudes.

  16. GRIPS - The Geostationary Remote Infrared Pollution Sounder

    NASA Astrophysics Data System (ADS)

    Spackman, Ryan; Dickerson, Russell; Schoeberl, Mark; Bloom, Hal; Gordley, Larry; McHugh, Martin; Thompson, Anne; Burrows, John; Zeng, Ning; Marshall, Tom; Fish, Chad; Kim, Jhoon; Park, Rokjin; Warner, Juying; Bhartia, Pawan; Kollonige, Debra

    2013-04-01

    Climate change and air quality are the most pressing environmental issues of the 21st century for America and for the world as a whole. Despite decades of research, the sources and sinks of key greenhouse gases and other pollutants remain highly uncertain making atmospheric composition predictions difficult. The Geostationary Remote Infrared Pollution Sounder (GRIPS) will measure carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4). By using measurements of nitrous oxide (N2O) and the O2 A-band to help correct for clouds and aerosols, GRIPS will achieve unprecedented precision. Together these gases account for about 85% of all climate forcing and they impact atmospheric ozone (O3). GRIPS, employing gas-filter correlation radiometry, uses the target gases themselves in place of dispersive elements to achieve outstanding throughput, sensitivity, and specificity. Because it uses a combination of reflected and thermal IR, GRIPS will detect trace gas concentrations right down to the Earth's surface. When flown in parallel to a UV/VIS sensor such as GEMS on GEO-KOMPSAT-2B over East Asia or the Sentinel 4 on MTG over Europe/Africa, the combination offers powerful finger-printing capabilities to distinguish and quantify diverse pollution sources such as electricity generation, biomass burning, and motor vehicles. From geostationary orbit, GRIPS will be able to focus on important targets to quantify sources, net flux, diurnal cycles, and long-range transport of these key components in the Earth's radiative balance and air quality.

  17. GRIPS - The Geostationary Remote Infrared Pollution Sounder

    NASA Astrophysics Data System (ADS)

    Dickerson, R. R.; Schoeberl, M. R.; Gordley, L. L.; McHugh, M. J.; Thompson, A. M.; Burrows, J. P.; Zeng, N.; Marshall, B. T.; Fish, C. S.; Spackman, J. R.; Kim, J.; Park, R.; Warner, J. X.; Bhartia, P. K.; Kollonige, D. E.

    2012-12-01

    Climate change and air quality are the most pressing environmental issues of the 21st century - for America and for the world as a whole. Despite decades of research, the sources and sinks of key greenhouse gases and other pollutants remain highly uncertain making atmospheric composition predictions difficult. The Geostationary Remote Infrared Pollution Sounder (GRIPS) will measure carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4). By using measurements of nitrous oxide (N2O) and the O2 A-band to help correct for clouds and aerosols, GRIPS will achieve unprecedented precision. Together these gases account for about 85% of all climate forcing and they impact atmospheric ozone (O3). GRIPS, employing gas-filter correlation radiometry, uses the target gases themselves in place of dispersive elements to achieve outstanding throughput, sensitivity, and specificity. Because it uses a combination of reflected and thermal IR, GRIPS will detect trace gas concentrations right down to the Earth's surface. When flown in parallel to a UV/VIS sensor such as GEMS on GEO-KOMPSAT-2B over East Asia or the Sentinel 4 on MTG over Europe/Africa, the combination offers powerful finger-printing capabilities to distinguish and quantify diverse pollution sources such as electricity generation, biomass burning, and motor vehicles. From geostationary orbit, GRIPS will be able to focus on important targets to quantify sources, net flux, diurnal cycles, and long-range transport of these key components in the Earth's radiative balance and air quality.

  18. Planetary protection for Europa radar sounder antenna

    NASA Astrophysics Data System (ADS)

    Aaron, Kim M.; Moussessian, Alina; Newlin, Laura E.; Willis, Paul B.; Chen, Fei; Harcke, Leif J.; Chapin, Elaine; Jun, Insoo; Gim, Yonggyu; McEachen, Michael; Allen, Scotty; Kirchner, Donald; Blankenship, Donald

    2016-05-01

    The potential for habitability puts stringent requirements on planetary protection for a mission to Europa. A long-wavelength radar sounder with a large antenna is one of the proposed instruments for a future Europa mission. The size and construction of radar sounding antennas make the usual methods of meeting planetary protection requirements challenging. This paper discusses a viable planetary protection scheme for an antenna optimized for Europa radar sounding. The preferred methodology for this antenna is exposure to 100 kGy (10 Mrad) in water of gamma radiation using a Cobalt-60 source for both bulk and surface sterilization and exposure to vapor hydrogen peroxide for surface treatment for possible recontamination due to subsequent handling. For the boom-supported antenna design, selected tests were performed to confirm the suitability of these treatment methods. A portion of a coilable boom residual from an earlier mission was irradiated and its deployment repeatability confirmed with no degradation. Elasticity was measured of several fiberglass samples using a four-point bending test to confirm that there was no degradation due to radiation exposure. Vapor hydrogen peroxide treatment was applied to the silver-coated braid used as the antenna radiating element as it was the material most likely to be susceptible to oxidative attack under the treatment conditions. There was no discernable effect. These tests confirm that the radar sounding antenna for a Europa mission should be able tolerate the proposed sterilization methods.

  19. Thermosphere-Ionosphere-Magnetosphere Coupling and Mass Outflow - the Magnetosphere/Ionosphere Perspective (Invited)

    NASA Astrophysics Data System (ADS)

    Wiltberger, M. J.

    2010-12-01

    Global scale models of the solar wind-magnetosphere-ionosphere interaction have long established history of including magnetosphere-ionosphere coupling through the electrodynamic coupling. Typically this coupling includes closure of field aligned currents from the magnetosphere in the electrostatic ionosphere with the conductances being modified by particle precipitation processes. Recent advances in simulation technology, namely multi-fluid MHD, allow the scope of MI coupling in simulations to include mass outflows from the thermosphere-ionosphere into the magnetosphere. Multiple approaches to addressing this challenge have been developed. In one approach empirical parametrization of the outflow characteristics, namely velocity and flux, are used to include high intensity sources such as the auroral zone and cusp. Another approach starts by modeling the plasma flow along a single field line and then expands to include multiple field lines convecting over the polar cap. In both approaches the ionospheric outflow has profound effects on the state of the magnetosphere. Generally speaking it improves agreement with Dst observations, alters the cross polar cap potential, and can fundamentally alter the evolution of the modeled magnetospheric state. Initial indications from some of the model efforts show that including this plasma source may also alter the solar wind-magnetosphere interaction. While significant advances on including these effects in global scale models has been accomplished many challenges remain.

  20. Ionospheric plasma cloud dynamics

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Measurements of the thermospheric neutral wind and ionospheric drift made at Eglin AFB, Florida and Kwajalein Atoll are discussed. The neutral wind measurements at Eglin had little variation over a period of four years for moderate magnetic activity (Kp 4); the ionospheric drifts are small. Evidence is presented that indicates that increased magnetic activity has a significant effect on the neutral wind magnitude and direction at this midlatitude station. The neutral wind at dusk near the equator is generally small although in one case out of seven it was significantly larger. It is described how observations of large barium releases can be used to infer the degree of electrodynamic coupling of ion clouds to the background ionosphere. Evidence is presented that indicates that large barium releases are coupled to the conjugate ionosphere at midlatitudes.

  1. High Latitude Ionospheric Structures

    DTIC Science & Technology

    2006-06-01

    CADI are a mixture of ionograms and ‘fixed’ frequency. The fixed frequency is chosen so as to get continuous ionospheric echoes throughout the day...because of the very dynamic ionospheric behaviour at high latitudes. Ionograms (interleaved with the fixed frequency observations) are at less frequent...intervals, typically each minute. In general it is easier to identify structures on the fixed frequency recordings. Ionograms are mainly useful when

  2. Dayside Ionospheric Superfountain

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Verkhoglyadova, Olga P.; Mannucci, Anthony J.

    2010-01-01

    The Dayside Ionospheric Super-fountain modified SAMI2 code predicts the uplift, given storm-time electric fields, of the dayside near-equatorial ionosphere to heights of over 800 kilometers during magnetic storm intervals. This software is a simple 2D code developed over many years at the Naval Research Laboratory, and has importance relating to accuracy of GPS positioning, and for satellite drag.

  3. Tsunami Ionospheric warning and Ionospheric seismology

    NASA Astrophysics Data System (ADS)

    Lognonne, Philippe; Rolland, Lucie; Rakoto, Virgile; Coisson, Pierdavide; Occhipinti, Giovanni; Larmat, Carene; Walwer, Damien; Astafyeva, Elvira; Hebert, Helene; Okal, Emile; Makela, Jonathan

    2014-05-01

    The last decade demonstrated that seismic waves and tsunamis are coupled to the ionosphere. Observations of Total Electron Content (TEC) and airglow perturbations of unique quality and amplitude were made during the Tohoku, 2011 giant Japan quake, and observations of much lower tsunamis down to a few cm in sea uplift are now routinely done, including for the Kuril 2006, Samoa 2009, Chili 2010, Haida Gwai 2012 tsunamis. This new branch of seismology is now mature enough to tackle the new challenge associated to the inversion of these data, with either the goal to provide from these data maps or profile of the earth surface vertical displacement (and therefore crucial information for tsunami warning system) or inversion, with ground and ionospheric data set, of the various parameters (atmospheric sound speed, viscosity, collision frequencies) controlling the coupling between the surface, lower atmosphere and the ionosphere. We first present the state of the art in the modeling of the tsunami-atmospheric coupling, including in terms of slight perturbation in the tsunami phase and group velocity and dependance of the coupling strength with local time, ocean depth and season. We then show the confrontation of modelled signals with observations. For tsunami, this is made with the different type of measurement having proven ionospheric tsunami detection over the last 5 years (ground and space GPS, Airglow), while we focus on GPS and GOCE observation for seismic waves. These observation systems allowed to track the propagation of the signal from the ground (with GPS and seismometers) to the neutral atmosphere (with infrasound sensors and GOCE drag measurement) to the ionosphere (with GPS TEC and airglow among other ionospheric sounding techniques). Modelling with different techniques (normal modes, spectral element methods, finite differences) are used and shown. While the fits of the waveform are generally very good, we analyse the differences and draw direction of future

  4. Study of stratospheric-ionospheric coupling during thunderstorms and tornadoes

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Smith, R. E.

    1977-01-01

    A continuous-wave-spectrum high-frequency Doppler sounder array with three transmitters at each of three sites was used to observe the dynamics of the coupling of energy between the stratosphere and the ionosphere. During times of severe weather activity wavelike disturbances have been detected on ground-based ionospheric sounding records as perturbations in electron densities. Infrasonic waves with wave periods of 3-7 min and with horizontal phase velocities of 600-800 m/s were observed when there was thunderstorm activity; gravity waves with wave periods of 10-15 min and horizontal phase velocities of 100-200 m/s were detected when there was tornado activity. Both triangulations from the cross correlation functions of the Doppler records based on an assumption of no background wind shear and ray-tracing computations including an assumed background wind shear indicate that the waves originated in the vicinity of the thunderstorms and tornadoes. A comparison of the wavelengths of the infrasonic and gravity waves observed at ionospheric heights and those in cloud-top pictures from satellites show that they are all of the order of 100-300 km.

  5. Magnetospheric and Ionospheric Response to Solar Wind Variability at Mars

    NASA Astrophysics Data System (ADS)

    Opgenoorth, H. J.; Andrews, D.; Edberg, N.; Lester, M.; Williams, A.; Fraenz, M.; Witasse, O.; Duru, F.; Morgan, D.

    2012-04-01

    At planets with induced magnetospheres the coupling between the ionosphere, the small draped magnetosphere and the solar wind is very direct in comparison to Earth. On the other hand it is more complicated as the weak induced magnetosphere itself is created by and in its shape and strength dynamically depending on the prevailing Solar wind conditions. In early 2010 Mars was located behind Earth in the Solar wind. In this study we utilized coordinated data from multiple near-Earth spacecraft (Stereo, ACE) to evaluate what kind of Solar wind disturbances have passed by Earth and might hit Mars consecutively (and when). We use plasma data from the ESA Mars- Express mission (mainly from the ASPERA particle instrument and the MARSIS topside ionospheric sounder) to investigate, for a number of isolated events in March and April 2010, how the induced magnetosphere at Mars develops and decays in response to Solar wind variability in the magnetic field, density and velocity, and what kind of ionospheric dynamics are produced in association with such events.

  6. Multi-GNSS for Ionospheric Scintillation Studies

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2015-12-01

    GNSS have been widely used for ionospheric monitoring. We anticipate over 160 GNSS satellites broadcasting 400 signals by 2023, nearly double the number today. With their well-defined signal structures, high spatial density and spectral diversity, GNSS offers low cost and distributed passive sensing of ionosphere effects. There are, however, many challenges to utilize GNSS resources to characterize and forecast ionospheric scintillation. Originally intended for navigation purposes, GNSS receivers are designed to filter out nuisance effects due to ionosphere effects. GNSS measurements are plagued with errors from multipath, oscillator jitters, processing artifacts, and neutral atmosphere effects. Strong scintillation events are often characterized by turbulent structures in ionosphere, causing simultaneous deep amplitude fading and abrupt carrier phase changes. The combined weak signal and high carrier dynamics imposes conflicting requirements for GNSS receiver design. Therefore, GNSS receivers often experience cycle slips and loss of lock of signals during strong scintillation events. High quality, raw GNSS signals bearing space weather signatures and robust receiver algorithms designed to capture these signatures are needed in order for GNSS to be a reliable and useful agent for scintillation monitoring and forecasting. Our event-driven, reconfigurable data collection system is designed to achieve this purpose. To date, our global network has collected ~150TB of raw GNSS data during space weather events. A suite of novel receiver processing algorithms has been developed by exploitating GNSS spatial, frequency, temporal, and constellation diversity to process signals experiencing challenging scintillation impact. The algorithms and data have advanced our understanding of scintillation impact on GNSS, lead to more robust receiver technologies, and enabled high spatial and temporal resolution depiction of ionosphere responses to solar and geomagnetic conditions. This

  7. Electron Density Profiles of the Topside Ionosphere

    NASA Technical Reports Server (NTRS)

    Huang, Xue-Qin; Reinsch, Bodo W.; Bilitza, Dieter; Benson, Robert F.

    2002-01-01

    The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h,F2 to - 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis- status.htm1. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2) down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling - 70% of the ionograms. An <> is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle.

  8. A Campaign to Study Equatorial Ionospheric Phenomena over Guam

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Balthazor, R.; Dearborn, M.; Enloe, L.; Lawrence, T.; McHarg, M.; Petrash, D.; Reinisch, B. W.; Stuart, T.

    2007-05-01

    With the development of a series of ground-based and space-based experiments, the United States Air Force Academy (USAFA) is in the process of planning a campaign to investigate the relationship between equatorial ionospheric plasma dynamics and a variety of space weather effects, including: 1) ionospheric plasma turbulence in the F region, and 2) scintillation of radio signals at low latitudes. A Digisonde Portable Sounder DPS-4 will operate from the island of Guam (with a magnetic latitude of 5.6° N) and will provide measurements of ionospheric total electron content (TEC), vertical drifts of the bulk ionospheric plasma, and electron density profiles. Additionally, a dual-frequency GPS TEC/scintillation monitor will be located along the Guam magnetic meridian at a magnetic latitude of approximately 15° N. In campaign mode, we will combine these ground-based observations with those collected from space during USAFA's FalconSAT-3 and FalconSAT-5 low-earth orbit satellite missions, the first of which is scheduled to be active over a period of several months beginning in the 2007 calendar year. The satellite experiments are designed to characterize in situ irregularities in plasma density, and include measurements of bulk ion density and temperature, minority-to- majority ion mixing ratios, small scale (10 cm to 1 m) plasma turbulence, and ion distribution spectra in energy with sufficient resolution for observations of non-thermalized distributions that may be associated with velocity- space instabilities. Specific targets of investigation include: a) a comparison of plasma turbulence observed on- orbit with spread F on ionograms as measured with the Digisonde, b) a correlation between the vertical lifting of the ionospheric layer over Guam and the onset of radio scintillation activity along the Guam meridian at 15° N magnetic latitude, and c) a correlation between on-orbit turbulence and ionospheric scintillation at 15° N magnetic latitude. These relationships

  9. Seismo-ionospheric transfer function: dependence on time, location and other special features

    NASA Astrophysics Data System (ADS)

    Astafyeva, E.; Rolland, L. M.; Lognonne, P.

    2010-12-01

    Large earthquakes are known to generate ionospheric disturbances, called coseismic ionosphere disturbances (CID). Vertical displacements of the ground induce pressure waves in the neutral atmosphere that propagate upward and grow in amplitude by several orders of magnitude as they reach ionospheric heights, since the atmospheric density decreases exponentially with height. Then, an ionospheric perturbation is formed via the collisions between neutral and charged particles. During favourable atmospheric and ionospheric conditions, a 0.1 mm/s ground displacement induced by the passage of Rayleigh surface waves generated by an earthquake of magnitude M8 at teleseismic distance, ionospheric layers can oscillate with velocities of about 10 m/s at around 150-200 km height. Those velocities are easily measurable by HF-Doppler sounder and significant Total Electron Content (TEC) variations (typically 0.1 TECU = 1x10^15 e-/m^3) can also be detected by GPS (Global Positioning System). However, before the emitted from the ground neutral waves reach the ionosphere they evolve due to a variety of effects provided by the propagation medium, i.e. the atmosphere. Therefore, one of the most interesting and important questions is the so-called transfer function for coseismic ionospheric disturbances that provides information on evolution and transformation of the “initial” neutral waves into the ultimate ionospheric response. This study analyzes the peculiarities of the transfer function for seismic waves in the ionosphere with respect to local time, geographical location, solar activity, etc. The variability of the solid Earth-atmosphere coupling is first investigated by estimating the amount of seismic energy injected in the atmosphere under variable atmospheric conditions. We model the atmospheric perturbation excited by an earthquake by summation of the Earth spheroidal normal modes computed for a 1D model of solid Earth surrounded by a realistic atmosphere. Further, through

  10. View to the eastnortheast of the Sounder Antenna OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the east-northeast of the Sounder Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  11. View to the northeast of the Sounder Antenna OvertheHorizon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View to the northeast of the Sounder Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

  12. International Reference Ionosphere -2010

    NASA Astrophysics Data System (ADS)

    Bilitza, Dieter; Reinisch, Bodo

    The International Reference Ionosphere 2010 includes several important improvements and ad-ditions. This presentation introduces these changes and discusses their benefits. The electron and ion density profiles for the bottomside ionosphere will be significantly improved by using more ionosonde data as well as photochemical considerations. As an additional lower iono-sphere parameter IRI-2010 will include the transition height from molecular to cluster ions. At the F2 peak Neural Net models for the peak density and the propagation factor M3000F2, which is related to the F2 peak height, are introduced as new options. At high latitudes the model will benefit from the introduction of auroral oval boundaries and their variation with magnetic activity. Regarding the electron temperature, IRI-2010 now models variations with solar activity. The homepage for the IRI project is at http://IRI.gsfc.nasa.gov/.

  13. Sensor System Performance Evaluation and Benefits from the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I)

    NASA Technical Reports Server (NTRS)

    Larar, A.; Zhou, D.; Smith, W.

    2009-01-01

    Advanced satellite sensors are tasked with improving global-scale measurements of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring, and environmental change detection. Validation of the entire measurement system is crucial to achieving this goal and thus maximizing research and operational utility of resultant data. Field campaigns employing satellite under-flights with well-calibrated FTS sensors aboard high-altitude aircraft are an essential part of this validation task. The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed-Interferometer (NAST-I) has been a fundamental contributor in this area by providing coincident high spectral/spatial resolution observations of infrared spectral radiances along with independently-retrieved geophysical products for comparison with like products from satellite sensors being validated. This paper focuses on some of the challenges associated with validating advanced atmospheric sounders and the benefits obtained from employing airborne interferometers such as the NAST-I. Select results from underflights of the Aqua Atmospheric InfraRed Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI) obtained during recent field campaigns will be presented.

  14. Ionospheric S-shaped Doppler fluctuations produced by the tornadoes

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Rao, G. L.; Smith, R. E.

    1974-01-01

    A three-dimensional nine element HF-CW Doppler sounder array has been used to detect ionospheric disturbances which may be due to tornadoes. The typical events chosen in the present study occurred on November 20 and 27, 1973. Both events are apparently associated with tornadoes sighted in the Huntsville, Alabama area. The Doppler records show S-shaped waves rather than the quasi-sinusoidal waves observed in conjunction with and apparently due to thunderstorms. The wave-periods are in the range of 6 to 8 minutes instead of the 3 to 5 minute periods associated with thunderstorms. Dissipation of waves is mostly due to the evanescent effect and they cannot propagate very far from the path of the tornado center. A theory is presented which is in good agreement with the observations.

  15. Characterizing Extreme Ionospheric Storms

    NASA Astrophysics Data System (ADS)

    Sparks, L.; Komjathy, A.; Altshuler, E.

    2011-12-01

    Ionospheric storms consist of disturbances of the upper atmosphere that generate regions of enhanced electron density typically lasting several hours. Depending upon the storm magnitude, gradients in electron density can sometimes become large and highly localized. The existence of such localized, dense irregularities is a major source of positioning error for users of the Global Positioning System (GPS). Consequently, satellite-based augmentation systems have been implemented to improve the accuracy and to ensure the integrity of user position estimates derived from GPS measurements. Large-scale irregularities generally do not pose a serious threat to estimate integrity as they can be readily detected by such systems. Of greater concern, however, are highly localized irregularities that interfere with the propagation of a signal detected by a user measurement but are poorly sampled by the receivers in the system network. The most challenging conditions have been found to arise following disturbances of large magnitude that occur only rarely over the course of a solar cycle. These extremely disturbed conditions exhibit behavior distinct from moderately disturbed conditions and, hence, have been designated "extreme storms". In this paper we examine and compare the behavior of the extreme ionospheric storms of solar cycle 23 (or, more precisely, extreme storms occurring between January 1, 2000, and December 31, 2008), as represented in maps of vertical total electron content. To identify these storms, we present a robust means of quantifying the regional magnitude of an ionospheric storm. Ionospheric storms are observed frequently to occur in conjunction with magnetic storms, i.e., periods of geophysical activity as measured by magnetometers. While various geomagnetic indices, such as the disturbance storm time (Dst) and the planetary Kp index, have long been used to rank the magnitudes of distinct magnetic storms, no comparable, generally recognized index exists for

  16. Identification of rocket-induced acoustic waves in the ionosphere

    NASA Astrophysics Data System (ADS)

    Mabie, Justin; Bullett, Terence; Moore, Prentiss; Vieira, Gerald

    2016-10-01

    Acoustic waves can create plasma disturbances in the ionosphere, but the number of observations is limited. Large-amplitude acoustic waves generated by energetic sources like large earthquakes and tsunamis are more readily observed than acoustic waves generated by weaker sources. New observations of plasma displacements caused by rocket-generated acoustic waves were made using the Vertically Incident Pulsed Ionospheric Radar (VIPIR), an advanced high-frequency radar. Rocket-induced acoustic waves which are characterized by low amplitudes relative to those induced by more energetic sources can be detected in the ionosphere using the phase data from fixed frequency radar observations of a plasma layer. This work is important for increasing the number and quality of observations of acoustic waves in the ionosphere and could help improve the understanding of energy transport from the lower atmosphere to the thermosphere.

  17. Suomi NPP/JPSS Cross-track Infrared Sounder (CrIS): Calibration Validation With The Aircraft Based Scanning High-resolution Interferometer Sounder (S-HIS)

    NASA Astrophysics Data System (ADS)

    Taylor, J. K.; Revercomb, H. E.; Tobin, D.; Knuteson, R. O.; Best, F. A.; Adler, D. A.; Pettersen, C.; Garcia, R. K.; Gero, P.

    2013-12-01

    To better accommodate climate change monitoring and improved weather forecasting, there is an established need for higher accuracy and more refined error characterization of radiance measurements from space and the corresponding geophysical products. This need has led to emphasizing direct tests of on-orbit performance, referred to as validation. Currently, validation typically involves (1) collecting high quality reference data from airborne and/or ground-based instruments during the satellite overpass, and (2) a detailed comparison between the satellite-based radiance measurements and the corresponding high quality reference data. Additionally, for future missions technology advancements at the University of Wisconsin Space Science and Engineering Center (UW-SSEC) have led to the development of an on-orbit absolute radiance reference utilizing miniature phase change cells to provide direct on-orbit traceability to International Standards (SI). The detailed comparison between the satellite-based radiance measurements and the corresponding measurements made from a high-altitude aircraft must account for instrument noise and scene variations, as well as differences in instrument observation altitudes, view angles, spatial footprints, and spectral response. Most importantly, for the calibration validation process to be both accurate and repeatable the reference data instrument must be extremely well characterized and understood, carefully maintained, and accurately calibrated, with traceability to absolute standards. The Scanning High-resolution Interferometer Sounder (S-HIS) meets and exceeds these requirements and has proven to do so on multiple airborne platforms, each with significantly different instrument operating environments. The Cross-track Infrared Sounder (CrIS) on Suomi NPP, launched 28 October 2011, is designed to give scientists more refined information about Earth's atmosphere and improve weather forecasts and our understanding of climate. CrIS is an

  18. GNSS monitoring of the ionosphere for Space Weather services

    NASA Astrophysics Data System (ADS)

    Krankowski, A.; Sieradzki, R.; Zakharenkova, I. E.; Cherniak, I. V.

    2012-04-01

    The International GNSS Service (IGS) Ionosphere Working Group routinely provides the users global ionosphere maps (GIMs) of vertical total electron content (vTEC). The IGS GIMs are provided with spatial resolution of 5.0 degrees x 2.5 degrees in longitude and latitude, respectively. The current temporal resolution is 2 hours, however, 1-hour maps are delivered as a pilot project. There are three types IGS GIMs: the final, rapid and predicted. The latencies of the IGS ionospheric final and rapid products are 10 days and 1 day, respectively. The predicted GIMs are generated for 1 and 2 days in advance. There are four IGS Associate Analysis Centres (IAACs) that provide ionosphere maps computed with independent methodologies using GNSS data. These maps are uploaded to the IGS Ionosphere Combination and Validation Center at the GRL/UWM (Geodynamics Research Laboratory of the University of Warmia and Mazury in Olsztyn, Poland) that produces the IGS official ionospheric products, which are published online via ftp and www. On the other hand, the increasing number of permanently tracking GNSS stations near the North Geomagnetic Pole allow for using satellite observations to detect the ionospheric disturbances at high latitudes with even higher spatial resolution. In the space weather service developed at GRL/UWM, the data from the Arctic stations belonging to IGS/EPN/POLENET networks were used to study TEC fluctuations and scintillations. Since the beginning of 2011, a near real-time service presenting the conditions in the ionosphere have been operational at GRL/UWM www site. The rate of TEC index (ROTI) expressed in TECU/min is used as a measure of TEC fluctuations. The service provides 2-hour maps of the TEC variability. In addition, for each day the daily map of the ionospheric fluctuations as a function geomagnetic local time is also created. This presentation shows the architecture, algorithms, performance and future developments of the IGS GIMs and this new space

  19. Ionospheric Modification by High Power, Obliquely Propagated HF Radio Wave Transmissions. Part 1. Experimental

    DTIC Science & Technology

    1993-07-01

    frequency of the disturbing transmitter is greater than the i.. asma frequency in the ionospheric interaction region. In fact, with many practical radio...NY) lay in the Gulf of Mexico and it was not possible to use an oblique probe system similar to- the technique used by the Soviets in their...using a vertical incidence sounder at Albuquerque, New Mexico (35.11N, 106.8 0W) at the midpoint of the 2400 km path. This technique insures that the

  20. Laser Atmospheric Wind Sounder (LAWS) phase 1. Volume 1: Executive summary

    NASA Astrophysics Data System (ADS)

    1990-04-01

    The laser atmospheric wind sounder (LAWS) will provide a new space based capability for the direct measurement of atmospheric winds in the troposphere. LAWS will make a major contribution toward advancing the understanding and prediction of the total Earth system and NASA's Earth Observing System (EOS) Program. LAWS is designed to measure a fundamental atmospheric parameter required to advance weather forecasting accuracies and investigate global climatic change. LAWS has a potential added benefit of providing (global) concentration profiles of large aerosols including visible and subvisible cirrus clouds, volcanic dust, smoke, and other pollutants. The objective of this Phase One study was to develop a LAWS concept and configuration. The instrument design is outlined in this first volume of three.

  1. Laser Atmospheric Wind Sounder (LAWS) phase 1. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The laser atmospheric wind sounder (LAWS) will provide a new space based capability for the direct measurement of atmospheric winds in the troposphere. LAWS will make a major contribution toward advancing the understanding and prediction of the total Earth system and NASA's Earth Observing System (EOS) Program. LAWS is designed to measure a fundamental atmospheric parameter required to advance weather forecasting accuracies and investigate global climatic change. LAWS has a potential added benefit of providing (global) concentration profiles of large aerosols including visible and subvisible cirrus clouds, volcanic dust, smoke, and other pollutants. The objective of this Phase One study was to develop a LAWS concept and configuration. The instrument design is outlined in this first volume of three.

  2. Film handling procedures for Apollo 17 lunar sounder

    NASA Technical Reports Server (NTRS)

    Weinstein, M. S.

    1972-01-01

    Film handling procedures for the Apollo 17 Lunar Sounder are itemized, including purchase of flight film, establishment of processing standards, transportation of flight films, flight film certification, application of pre- and post-sensitometry, film loading and downloading, film processing, titling, and duplication.

  3. Multi-station observation of ionospheric irregularities over South Africa during strong geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Amabayo, Emirant Bertillas; Cilliers Pierre, J.

    2013-03-01

    This paper presents results pertaining to the response of the mid-latitude ionosphere to strong geomagnetic storms that occurred from 31 March to 02 April 2001 and 07-09 September 2002. The results are based on (i) Global Positioning Systems (GPSs) derived total electron content (TEC) variations accompanying the storm, (ii) ionosonde measurements of the ionospheric electrodynamic response towards the storms and (iii) effect of storm induced travelling ionospheric disturbances (TIDs) on GPS derived TEC. Ionospheric data comprising of ionospheric TEC obtained from GPS measurements, ionograms, solar wind data obtained from Advanced Composition Explorer (ACE) and magnetic data from ground based magnetometers were used in this study. Storm induced features in vertical TEC (VTEC) have been obtained and compared with the mean VTEC of quiet days. The response of the mid-latitude ionosphere during the two storm periods examined may be characterised in terms of increased or decreased level of VTEC, wave-like structures in VTEC perturbation and sudden enhancement in hmF2 and h‧F. The study reveals both positive and negative ionospheric storm effects on the ionosphere over South Africa during the two strong storm conditions. These ionospheric features have been mainly attributed to the travelling ionospheric disturbances (TIDs) as the driving mechanism for the irregularities causing the perturbations observed. TEC perturbations due to the irregularities encountered by the satellites were observed on satellites with pseudo random numbers (PRNs) 15, 17, 18 and 23 between 17:00 and 23:00 UT on 07 September 2002.

  4. The effects of 450 kg surface explosions at the E layer of the ionosphere. Los Alamos Source Region Project

    SciTech Connect

    Fitzgerald, T.J.; Carlos, R.C.

    1992-10-22

    A network of hf ionospheric sounders consisting of two transmitter and two receiver stations was deployed to detect the effects of acoustic waves generated by surface ground motion following an underground nuclear test (UGT) at the Nevada Test Site. The frequency of the transmissions were chosen so that the hf radio waves were totally reflected in the E layer of the ionosphere at an altitude of approximately 100 km. The transmissions were highly stable cw tones at two frequencies separated by 100 kHz so that two altitudes separated by approximately .5 km could be sensed. The network sampled four geographic locations in the ionosphere ranging from almost directly overhead of the UGT out to a horizontal range of 60 km. The ionospheric sounders detected disturbances on all the paths beginning at approximately 325 s after the UGT which persisted for up to 100 s. These disturbances will be described in detail in a later paper. Shortly after the UGT an extended series of ionospheric disturbances were detected which we ascribe to the arrival of acoustic shock waves at the E layer caused by the surface detonation of ordinance with effective yields of 450 kg of high explosive during an unrelated exercise conducted by the U. S. Air Force at a nearby bombing range. The conjunction of these disturbances produced a direct comparison of the effects of UGT`s and surface explosions in the ionosphere. In this paper we describe the effects produced by the surface explosions and interpret the disturbance in terms of diffraction induced by electron density changes accompanying the passage of the acoustic waves from the explosions through the reflection altitudes.

  5. Optical Ionospheric Mapping.

    DTIC Science & Technology

    1983-12-15

    0325 I OPTICAL IONOSPHERIC MAPPING Robert H. Eather KEO Consultants 00 27 Irving St. Lfl Brookline Massachusetts 02146 I J CI Final Report U July 28...Irving St. Brookline Ma. 02146 464306AL It. CONTROLLING OFFICE NAME AND ADDRESS 12 REPORT DA ,F Air Force Geophysics Laboratory December 15, 1983

  6. Global Ionospheric Processes

    DTIC Science & Technology

    2008-10-29

    the all-sky imager during the September 2008 Kwajalein C/NOFS campaign 5 3. Ionograms and optical images from conjugate hemispheres during...conjugacy of large-scale ionospheric structures. 6 Figure 3. Ionograms and optical images from conjugate hemispheres during the COPEX experiment

  7. RF Heating the Ionosphere,

    DTIC Science & Technology

    1987-08-01

    Kopka, Geophys. Res. Lett. 11, 523 (1984). 4. H.C. Carlson, V.B. Wickwar, and G. P. Mantas, J. Atmos. and Terr. Phys. 44, 1089 (1982) 5. E. Mjolhus and T...Ionosphere," G. J. Morales, presented at the Seventh APS Topical Conference, Kissimmee, Florida, May 4-6, 1987. PPG- 1089 "Self-Consistent Modification

  8. Ionospheric total-electron-content estimation for single-frequency Global-positioning-system receivers

    SciTech Connect

    Smith, C.A.

    1987-01-01

    The ionosphere delays transmissions from the Global Positioning System (GPS), as well as those from other satellite systems. At the GPS frequencies (L-Band), this delay is directly proportional to the total ionospheric electron content (TEC) along the line-of-sight to the satellite. Classified receivers have access to 2 frequencies to allow them to measure this delay through the difference in the ionospheric effect at the 2 frequencies, but commercial, single-frequency receivers have had no direct method for estimating the ionospheric delay; they have had to rely on a TEC prediction. Two methods are described for single-frequency GPS receivers to estimate the ionospheric TEC directly. These methods take advantage of the dispersive nature of the ionosphere at L-Band frequencies, which causes a phase advance of the carrier that is opposite to the group delay of the GPS code and data.

  9. Martian ionosphere response to solar wind variability during solar minimum

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Mays, M. Leila; Hall, Benjamin E. S.; Milan, Stephen E.; Cartacci, Marco; Blelly, Pierre-Louis; Andrews, David; Opgenoorth, Hermann; Odstrcil, Dusan

    2016-04-01

    Solar cycle variations in solar radiation create notable density changes in the Martian ionosphere. In addition to this long-term variability, there are numerous short-term and non-recurrent solar events that hit Mars which need to be considered, such as Interplanetary Coronal Mass Ejections (ICMEs), Co-Rotation Interaction Regions (CIRs), solar flares, or solar wind high speed streams. The response of the Martian plasma system to each of these events is often unusual, especially during the long period of extreme low solar activity in 2008 and 2009. This work shows the long-term solar cycle impact on the ionosphere of Mars using data from The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), and The Analyzer of Space Plasma and Energetic Atoms (ASPERA-3), and with empirical and numerical models on Mars Express. Particular attention is given to the different ionospheric responses observed during the last, extended solar minimum. Mars' ionospheric response followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to the inner-origin of the magnetic field of both planets. The ionospheric temperature was cooler, the topside scale height was smaller and almost constant with altitude, the secondary ionospheric layer practically disappeared and the whole atmospheric total electron content (TEC) suffered an extreme reduction of about 30-40%, not predicted before by models. Moreover, there is a larger probability for the induced magnetic field to be present in the ionosphere, than in other phases of the solar cycle. The short-term variability is also addressed with the study of an ICME followed by a fast stream that hit Mars in March 2008, where solar wind data are provided by ACE and STEREO-B and supported by simulations using the WSA-ENLIL Model. The solar wind conditions lead to the formation of a CIR centred on the interface of the fast and the slow solar wind streams. Mars' system reacted to

  10. 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.

  11. Ionospheric disturbances in Asian region of Russia during sudden stratospheric warmings

    NASA Astrophysics Data System (ADS)

    Kurkin, Vladimir; Chernigovskaya, Marina; Medvedeva, Irina; Orlov, Igor

    This paper presents an investigation of the subauroral and mid-latitude ionosphere variations in the Asian region of Russia during stratospheric warmings in 2008, 2009 and 2010. We used the data from network of vertical and oblique-incidence sounding ionosounders of ISTP SB RAS. Irkutsk chirp-sounder (vertical incidence sounding) run every 1 minute on 24-hour basis for 30 days in winter of 2008, 2009 and 2010 to study small-scale and medium-scale distur-bances. The experiments on the radio paths Magadan-Irkutsk, Khabarovsk-Irkutsk and Norilsk -Irkutsk were conducted in order to study large-scale ionospheric disturbances. The frequency range was from 4 to 30 MHz, the sweep rate used 500 kHz/sec. To identify the stratospheric warming events the Berlin Meteorological University data (http://strat-www.met.fu-berlin.de) on stratospheric warming at standard isobaric levels and the atmospheric temperature height profiles measured by the Microwave Limb Sounder (MLS) aboard the EOS Aura spacecraft were used. The increase of wave activity in upper ionosphere over Asian region of Russia has recorded during stratospheric warmings. Spectrums of multi-scale variations were derived from the data obtained during the prolonged experiments. The analysis of experimental data has revealed the amplitudes of planetary waves in ionosphere during stratospheric warmings in 2008 and 2010 larger than ones in winter 2009 as opposed to amplitude variations of temperature in stratosphere. This work was supported by Russian Foundation for Basic Research (grant 08-05-00658).

  12. Chemistry in the Thermosphere and Ionosphere.

    ERIC Educational Resources Information Center

    Roble, Raymond G.

    1986-01-01

    An informative review which summarizes information about chemical reactions in the thermosphere and ionosphere. Topics include thermal structure, ultraviolet radiation, ionospheric photochemistry, thermospheric photochemistry, chemical heating, thermospheric circulation, auroral processes and ionospheric interactions. Provides suggested followup…

  13. High-latitude ionospheric outflows characterized through analytic formulas

    NASA Astrophysics Data System (ADS)

    Zeng, W.; Horwitz, J. L.

    2008-12-01

    Recent advances involving multi-fluid treatments have begun to allow the prospect of global magnetospheric models to simulate the dynamics of multiple ion species, such as various ion species originating from sources in the solar wind and terrestrial ionosphere. Such opportunities for the dynamic treatment of ionospheric ions within the magnetosphere portend a need for realistic accessible methods of estimating ionospheric outflows as linked plasma sources for these global models. Toward this end, in this presentation, the results of numerous physics-based simulations of ionospheric plasma outflows under varied driving agents are distilled in terms of relatively compact analytic expressions. The simulations are conducted with the UT Arlington Dynamic Fluid (DyFK) ionospheric plasma transport code. These analytic expressions for O+ and H+ densities, temperatures and flow velocities are obtained at the 3 RE altitudes corresponding to typical inner boundary levels for certain current global magnetospheric models. These O+ and H+ parameters are expressed as functions of precipitation electron energy flux levels, characteristic energy levels of the precipitating electrons, the peak spectral wave densities for low-frequency electrostatic waves which transversely heat ionospheric ions, and solar zenith angle.

  14. Oblique ionospheric reflections in the MARSIS data set

    NASA Astrophysics Data System (ADS)

    Andrews, D. J.; Duru, F.; Morgan, D. D.; Opgenoorth, H. J.; Witasse, O. G.; Withers, P.

    2012-12-01

    In addition to reflections from the Martian ionosphere along the nadir direction, the Mars Advanced Radar for Sub-surface and Ionospheric Sounding (MARSIS) on board ESA's Mars Express (MEX) orbiter frequently detects 'oblique reflections' from additional targets away from the nadir direction. Such oblique reflections have been attributed to the presence of anomalous horizontal structure within the ionosphere, in which the ionospheric scale height is thought to have increased in regions where Mars' remnant crustal magnetic field has a 'open' or cusp-like configuration, possibly allowing for the heating of the ionosphere by precipitating solar wind plasma. This spatial structuring gives constant-density surfaces which are not parallel to the planet's surface, from which the sounding pulse from the MARSIS instrument can be reflected back towards the spacecraft at what would otherwise be oblique incidence. These oblique reflections form distinctive hyperbolas in time and apparent range, the apices of which are generally above the surrounding ionosphere, strongly suggesting that they have an extended horizontal structure. Here, employing the substantial MARSIS data set, we examine both the spatial distribution and repeatability of detection of these oblique reflections. These results are then related to the highly structured Martian crustal magnetic field, utilising a simplified ray-tracing code.

  15. Oblique ionospheric reflections in the MARSIS data set

    NASA Astrophysics Data System (ADS)

    Andrews, David; Duru, Firdevs; Morgan, David; Opgenoorth, Hermann; Witasse, Olivier; Withers, Paul

    2013-04-01

    In addition to reflections from the Martian ionosphere along the nadir direction, the Mars Advanced Radar for Sub-surface and Ionospheric Sounding (MARSIS) on board ESA's Mars Express (MEX) orbiter frequently detects 'oblique reflections' from additional targets away from the nadir direction. Such oblique reflections have been attributed to the presence of anomalous horizontal structure within the ionosphere, in which the ionospheric scale height is thought to have increased in regions where Mars' remnant crustal magnetic field has a 'open' or cusp-like configuration, possibly allowing for the heating of the ionosphere by precipitating solar wind plasma. This spatial structuring gives constant-density surfaces which are not parallel to the planet's surface, from which the sounding pulse from the MARSIS instrument can be reflected back towards the spacecraft at what would otherwise be oblique incidence. These oblique reflections form distinctive hyperbolas in time and apparent range, the apices of which are generally above the surrounding ionosphere, strongly suggesting that they have an extended horizontal structure. Here, employing the substantial MARSIS data set, we examine both the spatial distribution and repeatability of detection of these oblique reflections. These results are then related to the highly structured Martian crustal magnetic field, utilising a simplified ray-tracing code.

  16. Ensemble Ionospheric Total Electron Content Forecasting during Storms

    NASA Astrophysics Data System (ADS)

    Chartier, A.; Mitchell, C. N.; Lu, G.; Anderson, J. L.; Collins, N.; Hoar, T. J.; Bust, G. S.; Matsuo, T.

    2014-12-01

    Earth's ionosphere presents a threat to human activities such as satellite positioning and timing, radio communications and surveillance. Nowcasts and forecasts of the ionosphere could help mitigate these damaging effects. Recent advances in the field of ionospheric imaging, as well as new storm-time ionospheric forecasting results are presented here. The approach combines globally distributed GPS Total Electron Content (TEC) measurements with an ensemble of coupled thermosphere-ionosphere models in order to produce short-term forecasts during a storm. One-hour forecast accuracy is much better than a climatological model run. Using this ensemble approach, it is possible to infer the neutral O/N2 ratio from TEC measurements so that subsequent TEC forecasts are improved. A review of ionospheric physics and data assimilation will also be given. The term data assimilation refers to a group of techniques designed to estimate atmospheric or oceanic states. In practice, data assimilation techniques seek to improve modeled estimates of the atmospheric state by incorporating observations. The relationship between data assimilation and forecasting is explored with reference to the physics of the thermosphere-ionosphere system. The work presented here uses the Data Assimilation Research Testbed (DART), which is an ensemble Kalman filter data assimilation framework. This is combined with a version of the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) that has been modified to accept more detailed solar and geomagnetic driver specifications. Future directions of work include the inference of Solar and geomagnetic drivers from the data assimilation process as well as coupling with lower-atmospheric models.

  17. A regional adaptive and assimilative three-dimensional ionospheric model

    NASA Astrophysics Data System (ADS)

    Sabbagh, Dario; Scotto, Carlo; Sgrigna, Vittorio

    2016-03-01

    A regional adaptive and assimilative three-dimensional (3D) ionospheric model is proposed. It is able to ingest real-time data from different ionosondes, providing the ionospheric bottomside plasma frequency fp over the Italian area. The model is constructed on the basis of empirical values for a set of ionospheric parameters Pi[base] over the considered region, some of which have an assigned variation ΔPi. The values for the ionospheric parameters actually observed at a given time at a given site will thus be Pi = Pi[base] + ΔPi. These Pi values are used as input for an electron density N(h) profiler. The latter is derived from the Advanced Ionospheric Profiler (AIP), which is software used by Autoscala as part of the process of automatic inversion of ionogram traces. The 3D model ingests ionosonde data by minimizing the root-mean-square deviation between the observed and modeled values of fp(h) profiles obtained from the associated N(h) values at the points where observations are available. The ΔPi values are obtained from this minimization procedure. The 3D model is tested using data collected at the ionospheric stations of Rome (41.8N, 12.5E) and Gibilmanna (37.9N, 14.0E), and then comparing the results against data from the ionospheric station of San Vito dei Normanni (40.6N, 18.0E). The software developed is able to produce maps of the critical frequencies foF2 and foF1, and of fp at a fixed altitude, with transverse and longitudinal cross-sections of the bottomside ionosphere in a color scale. fp(h) and associated simulated ordinary ionogram traces can easily be produced for any geographic location within the Italian region. fp values within the volume in question can also be provided.

  18. Thermal structure of the ionosphere

    NASA Technical Reports Server (NTRS)

    Brace, L. H.

    1975-01-01

    A brief review is presented of recent progress made toward gaining a more complete understanding of the thermal structure of the ionosphere. Important heat sources for the ionosphere are described, including the solar EUV flux, midlatitude interactions between the magnetosphere and ionosphere, electric-field enhancements at high latitudes, particle precipitation in the auroral oval, and polar-wind heating. Discrepancies between electron-temperature measurements by satellite probes and incoherent-backscatter techniques are noted.

  19. Planetary waves in rotating ionosphere

    SciTech Connect

    Khantadze, A. G.; Jandieri, V. G.; Jandieri, G. V.

    2008-06-15

    The problem of propagation of ultralong planetary waves in the Earth's upper atmosphere is considered. A new exact solution to the MHD equations for the ionosphere is obtained in spherical coordinates with allowance for the geomagnetic field and Earth's rotation. A general dispersion relation is derived for planetary waves in the ionospheric E and F regions, and the characteristic features of their propagation in a weakly ionized ionospheric plasma are discussed.

  20. Ionospheric disturbance dynamo

    SciTech Connect

    Blanc, M.; Richmond, A.D.

    1980-04-01

    A numerical simulation study of the thermospheric winds produced by auroral heating during magnetic storms, and of their global dynamo effects, establishes the main features of the ionospheric disturbanc dynamo. Driven by auroral heating, a Hadley cell is created with equatorward winds blowing above about 120 km at mid-latitudes. The transport of angular momentum by these winds produces a subrotation of the midlatitude thermosphere, or westward motion with respect to the earth. The westward winds in turn drive equatorward Pedersen currents which accumulate charge toward the equator, resulting in the generation of a poleward electric field, a westward E x B drift, and an eastward current. When realistic local time conductivity variations are simulated, the eastward mid-latitude current is found to close partly via lower latitudes, resulting in an 'anti-Sq' type of current vortex. Both electric field and current at low latitudes thus vary in opposition to their normal quiet-day behavior. This total pattern of distrubance winds, electric fields, and currents is superimposed upon the background quiet-day pattern. When the neutral winds are artificially confined on the nightside, the basic pattern of predominantly westward E x B plasma drifts still prevails on the nightside but no longer extends into the dayside. Considerable observational evidence exists, suggesting that the ionospheric disturbance dynamo has an appreciable influence on storm-time ionospheric electric fields at middle and low latitudes.

  1. Relating OGO-5 H(+) Plasmapause Transitions to Mid-Latitude Topside-Ionospheric Signatures

    NASA Technical Reports Server (NTRS)

    Truhlik, Vladimir; Benson, Robert F.; Bilitza, Dieter; Grebowsky, Joseph M.; Wang, Yongli

    2009-01-01

    Plasmapause transitions, as seen in the H + and He+ density gradients measured by the Orbiting Geophysical Observatory 5 (OGO 5) ion spectrometer [Sharp, IEE Trans. in Geosci. Elect., 1969], have been investigated in an attempt to relate them to their topside ionospheric signatures as seen in the Alouette-1 & 2 and ISIS-1 data. The satellite data were obtained from the National Space Science Data Center (NSSDC). A search of the OGO-5 data revealed 54 sharp plasmapause crossings as evaluated from the H+ density. The ionospheric footprints (at 1400 km altitude) of the magnetic-field lines through the locations of these plasmapause crossings were then used to search for topside ionospheric electron-density profiles from the NSSDC. No profiles corresponding to these projections were identified. A similar search of the topside-sounder 35-mm ionogram-film database, however, identified 17 cases of candidate "conjunctions" involving Alouette l & 2 and ISIS 1. We will present samples of the plasmapause OGO-5 ion transitions and the related topside ionospheric signatures and discuss the observations in relation to the recent similar study based on Explorer-45 and ISIS-2 data [Grebowsky et al., JASTP, 2009].

  2. Next Generation Grating Spectrometer Sounders for LEO and GEO

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.

    2011-01-01

    AIRS and MODIS are widely used for weather, climate, composition, carbon cycle, cross-calibration, and applications. The community asking for new capability in the 2020 timeframe, capabilities desired: (1) Hyperspectral UV to LWIR, High Spatial ?1km IFOV (2) Maximize Synergies of Solar Reflected and IR. Synergies with OCO-2. We expect more users and applications of next gen LEO IR Sounder than GEO. These include: weather, climate, GHG monitoring, aviation, disaster response. There is a new direction for imagers and sounders: (1) Separate Vis/NIR/SWIR from MWIR/LWIR instruments reduces technology risk and complexity. (2) Expect Costs to be lower than CrIS & VIIRS Some additional ideas to reduce costs include: (1) minimum set of requirements (2) mini-grating spectrometers. supports constellation for higher revisit (3) new technology to reduce instrument size (large format fpa's) (4) hosted payloads

  3. High resolution microwave spectrometer sounder (HIMSS), volume 1, book 2

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The following topics are presented with respect to the high resolution microwave spectrometer sounder (HIMSS) that is to be used as an instrument for NASA's Earth Observing System (EOS): (1) preliminary program plans; (2) contract end item (CEI) specification; and (3) the instrument interface description document. Under the preliminary program plans section, plans dealing with the following subject areas are discussed: spares, performance assurance, configuration management, software implementation, contamination, calibration management, and verification.

  4. On Cirrus Cloud Fields Measured by the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Kahn, Brian H.; Eldering, Annmarie; Liou, Kuo Nan

    2006-01-01

    A viewgraph presentation showing trends in clouds measured by the Atmospheric Infrared Sounder (AIRS) is given. The topics include: 1) Trends in clouds measured by AIRS: Are they reasonable? 2) Single and multilayered cloud trends; 3) Retrievals of thin cirrus D(sub e) and tau: Single-layered cloud only; 4) Relationships between ECF, D(sub e), tau, and T(sub CLD); and 5) MODIS vs. AIRS retrievals.

  5. The Mars Climate Sounder on the Mars Reconnaissance Orbiter

    NASA Astrophysics Data System (ADS)

    McCleese, D.; Taylor, F.; Schofield, J.; Calcutt, S.

    2003-04-01

    There remains a need for an intensive effort to obtain a climatology of the martian atmosphere. This objective was to have been accomplished with the Mars Observer and with the Mars Climatology Orbiter, both of which failed at Mars. In 2005, the Mars Reconnaissance Orbiter will carry the Mars Climate Sounder (MCS) to aquire the necessary measurements of the vertical profiles of atmospheric temperature, water vapor, dust and condensates. This paper describes the climate objectives and measurement approach of MCS.

  6. High resolution microwave spectrometer sounder (HIMSS), volume 1, book 1

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The following topics are presented with respect to the high resolution microwave spectrometer sounder (HIMSS) that is to be used as an instrument for NASA's Earth Observing System (EOS): (1) an instrument overview; (2) an instrument description; (3) the instrument's conceptual design; (4) technical risks and offsets; (5) instrument reliability; (6) commands and telemetry; (7) mass and power budgets; (8) integration and test program; (9) program implementation; and (10) phase CD schedule.

  7. The Apollo 17 Lunar Sounder. [lunar orbit coherent radar experiment

    NASA Technical Reports Server (NTRS)

    Phillips, R. J.; Brown, W. E., Jr.; Jordan, R.; Adams, G. F.; Jackson, P.; Peeples, W. J.; Porcello, L. J.; Ryu, J.; Eggleton, R. E.; Schaber, G.

    1973-01-01

    The Apollo Lunar Sounder Experiment, a coherent radar operated from lunar orbit during the Apollo 17 mission, has scientific objectives of mapping lunar subsurface structure, surface profiling, surface imaging, and galactic noise measurement. Representative results from each of the four disciplines are presented. Subsurface reflections have been interpreted in both optically and digitally processed data. Images and profiles yield detailed selenomorphological information. The preliminary galactic noise results are consistent with earlier measurements by other workers.

  8. Sonic depth sounder for laboratory and field use

    USGS Publications Warehouse

    Richardson, E.V.; Simons, Daryl B.; Posakony, G.J.

    1961-01-01

    The laboratory investigation of roughness in alluvial channels has led to the development of a special electronic device capable of mapping the streambed configuration under dynamic conditions. This electronic device employs an ultrasonic pulse-echo principle, similar to that of a fathometer, that utilizes microsecond techniques to give high accuracy in shallow depths. This instrument is known as the sonic depth sounder and was designed to cover a depth range of 0 to 4 feet with an accuracy of ? 0.5 percent. The sonic depth sounder is capable of operation at frequencies of 500, 1,000 and 2,000 kilocycles. The ultrasonic beam generated at the transducer is designed to give a minimum-diameter interrogating signal over the extended depth range. The information obtained from a sonic depth sounder is recorded on a strip-chart recorder. This permanent record allows an analysis to be made of the streambed configuration under different dynamic conditions. The model 1024 sonic depth sounder was designed principally as a research instrument to meet laboratory needs. As such, it is somewhat limited in its application as a field instrument on large streams and rivers. The principles employed in this instrument, however, have many potentials for field applications such as the indirect measurement of bed load when the bed roughness is ripples and (or) dunes, depth measurement, determination of bed configuration, and determination of depth of scour around bridge piers and abutments. For field application a modification of the present system into a battery-operated lightweight instrument designed to operate at a depth range of 0 to 30 feet is possible and desirable.

  9. Daily global maps of carbon monoxide from NASA's Atmospheric Infrared Sounder

    NASA Astrophysics Data System (ADS)

    McMillan, W. W.; Barnet, C.; Strow, L.; Chahine, M. T.; McCourt, M. L.; Warner, J. X.; Novelli, P. C.; Korontzi, S.; Maddy, E. S.; Datta, S.

    2005-06-01

    We present the first observations of tropospheric carbon monoxide (CO) by the Atmospheric Infrared Sounder (AIRS) onboard NASA's Aqua satellite. AIRS daily coverage of ~70% of the planet represents a significant evolutionary advance in satellite trace gas remote sensing. Tropospheric CO abundances are retrieved from AIRS 4.55 μm spectral region using the full AIRS retrieval algorithm run in a research mode. The presented AIRS daily global CO maps from 22-29 September 2002 show large-scale, long-range transport of CO from anthropogenic and natural sources, most notably from biomass burning. The sequence of daily maps reveal CO advection from Brazil to the South Atlantic in qualitative agreement with previous observations. Forward trajectory analysis confirms this scenario and indicates much longer range transport into the southern Indian Ocean. Preliminary comparisons to in situ aircraft profiles indicate AIRS CO retrievals are approaching the 15% accuracy target set by pre-launch simulations.

  10. Efficient simultaneous image deconvolution and upsampling algorithm for low-resolution microwave sounder data

    NASA Astrophysics Data System (ADS)

    Qin, Jing; Yanovsky, Igor; Yin, Wotao

    2015-01-01

    Microwave imaging has been widely used in the prediction and tracking of hurricanes, typhoons, and tropical storms. Due to the limitations of sensors, the acquired remote sensing data are usually blurry and have relatively low resolution, which calls for the development of fast algorithms for deblurring and enhancing the resolution. We propose an efficient algorithm for simultaneous image deconvolution and upsampling for low-resolution microwave hurricane data. Our model involves convolution, downsampling, and the total variation regularization. After reformulating the model, we are able to apply the alternating direction method of multipliers and obtain three subproblems, each of which has a closed-form solution. We also extend the framework to the multichannel case with the multichannel total variation regularization. A variety of numerical experiments on synthetic and real Advanced Microwave Sounding Unit and Microwave Humidity Sounder data were conducted. The results demonstrate the outstanding performance of the proposed method.

  11. Application of Atmospheric Infrared Sounder (AIRS) Data to Climate Research

    NASA Technical Reports Server (NTRS)

    Aumann, Hartmut H.; Gregorich, David; Gaiser, Steve; Chahine, Moustafa T.

    2004-01-01

    The application of hyper spectral radiometric data to climate research requires very high absolute radiometric accuracy and stability. We use cloud-free tropical ocean data from the Atmospheric InfraRed Sounder (AIR) Calibration Data Subset (ADCS) to show that the radiometric precision and stability required climate applications has been achieved. The sea surface skin temperatures derived from the AIRS 2616cm-1 super window channel are stable relative to the RTG.SST at the better than 8 mK/year level, and the spectral calibration is stable at the 1 ppm/year level. The excellent stability and accuracy are the result of the implementation of AIRS as a grating array spectrometer, which is cooled and stabilized within 10 mK at 155 K. Analysis of daily measurements of the temperature gradient between the surface and 7 km altitude show that the AIRS Calibration Data Subset has applications which extend its original intent for calibration support to climate research. The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua satellite was launched into polar orbit in May 2002. AIRS covers the spectral region from 640 to 2700 cm-1 with 2378 independent channels and represents the first of a new generation of hyper spectral resolution sounders in support of global sounding data for weather forecasting and climate research.

  12. A laser sounder for U.S. Navy helicopters

    NASA Technical Reports Server (NTRS)

    Harris, Michael M.; Mesick, Hillary C.; Byrnes, H. Jerry; Curran, Thomas P.; Contarino, V. Michael

    1987-01-01

    The design and operating principles of the laser sounder developed for use in airborne coastal-zone bathymetric surveys with a U.S. Navy P-3 aircraft are described and illustrated with diagrams. The sounder components are listed and characterized, including the Nd:YAG transmitter (operating at 532 nm for bottom ranging and 1.064 microns for surface ranging), the scanning transceiver, the 10 x 6-inch-aperture controlled-FOV receiver/digitizer, the constant-fraction discriminator, the time-to-digital converter, the navigation and data-recording subsystems, and the parallel distributed processing computer (comprising a data collection and control system and a real-time processing system). Consideration is also given to the phase-I and phase-II data-reduction software being developed to process the approximately 228 million soundings to be obtained annually. The sounder can be used day or night to sound clear ocean water up to 20 m deep.

  13. Lossless data compression for infrared hyperspectral sounders: an update

    NASA Astrophysics Data System (ADS)

    Huang, Bormin; Huang, Hung-Lung A.; Ahuja, Alok; Schmit, Timothy J.; Heymann, Roger W.

    2004-10-01

    The compression of hyperspectral sounder data is beneficial for more efficient archive and transfer given its large 3-D volume. Moreover, since physical retrieval of geophysical parameters from hyperspectral sounder data is a mathematically ill-posed problem that is sensitive to the error of the data, lossless or near-lossless compression is desired. This paper provides an update into applications of state-of-the-art 2D and 3D lossless compression algorithms such as 3D EZW, 3D SPIHT, 2D JPEG2000, 2D JPEG-LS and 2D CALIC for hyperspectral sounder data. In addition, in order to better explore the correlations between the remote spectral regions affected by the same type of atmospheric absorbing constituents or clouds, the Bias-Adjusted Reordering (BAR) scheme is presented which reorders the data such that the bias-adjusted distance between any two neighboring vectors is minimized. This scheme coupled with any of the state-of-the-art compression algorithms produces significant compression gains.

  14. Satellite Sounder Data Assimilation for Improving Alaska Region Weather Forecast

    NASA Technical Reports Server (NTRS)

    Zhu, Jiang; Stevens, E.; Zhang, X.; Zavodsky, B. T.; Heinrichs, T.; Broderson, D.

    2014-01-01

    A case study and monthly statistical analysis using sounder data assimilation to improve the Alaska regional weather forecast model are presented. Weather forecast in Alaska faces challenges as well as opportunities. Alaska has a large land with multiple types of topography and coastal area. Weather forecast models must be finely tuned in order to accurately predict weather in Alaska. Being in the high-latitudes provides Alaska greater coverage of polar orbiting satellites for integration into forecasting models than the lower 48. Forecasting marine low stratus clouds is critical to the Alaska aviation and oil industry and is the current focus of the case study. NASA AIRS/CrIS sounder profiles data are used to do data assimilation for the Alaska regional weather forecast model to improve Arctic marine stratus clouds forecast. Choosing physical options for the WRF model is discussed. Preprocess of AIRS/CrIS sounder data for data assimilation is described. Local observation data, satellite data, and global data assimilation data are used to verify and/or evaluate the forecast results by the MET tools Model Evaluation Tools (MET).

  15. High-resolution Interferometer Sounder (HIS), phase 2

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The High-resolution Interferometer Sounder (HIS) was successfully built, tested, and flight proven on the NASA U-2/ER-2 high altitude aircraft. The HIS demonstration has shown that, by using the technology of Fourier Transform Spectroscopy (FTS), it is possible to measure the spectrum of upwelling infrared radiance needed for temperature and humidity sounding with high spectral resolution and high radiometric precision. By resolving individual carbon dioxide lines, the retrieved temperature profiles have vertical resolutions of 1 to 2 km and RMS errors less than 1 C, about 2 to 4 times better than possible with current sounders. Implementing this capability on satellite sounders will greatly enhance the dynamical information content of temperature measurements from space. The aircraft model HIS is now a resource which should be used to support field experiments in mesoscale meteorology, to monitor trace gas concentrations and to better understand their effects on climate, to monitor the surface radiation budget and the radiative effects of clouds, and to collect data for research into retrieval techniques, especially under partially cloudy conditions.

  16. Carbon Monoxide Distribution over Peninsular Malaysia from the Atmospheric Infrared Sounder (AIRS)

    NASA Astrophysics Data System (ADS)

    Rajab, Jaso M.; MatJafri, M. Z.; Lim, H. S.; Abdullah, K.

    2009-07-01

    The Atmospheric Infrared Sounder (AIRS) onboard NASA's Aqua satellite. It daily coverage of ˜70% of the planet represents a significant evolutionary advance in satellite traces gas remote sensing. AIRS, the part of a large international investment to upgrade the operational meteorological satellite systems, is first of the new generation of meteorological advanced sounders for operational and research use, Providing New Insights into Weather and Climate for the 21st Century. Carbon monoxide (CO) is a ubiquitous, an indoor and outdoor air pollutant, is not a significant greenhouse gas as it absorbs little infrared radiation from the Earth. However, it does have an influence on oxidization in the atmosphere through interaction with hydroxyl radicals (OH), which also react with methane, halocarbons and tropospheric ozone. It produced by the incomplete combustion of fossil fuels and biomass burning, and that it has a role as a smog. The aim of this investigation is to study the (CO) carbon monoxide distribution over Peninsular Malaysia. The land use map of the Peninsular Malaysia was conducted by using CO total column amount, obtained from AIRS data, the map & data was processed and analyzed by using Photoshop & SigmaPlot 11.0 programs and compared for timing of various (day time) (28 August 2005 & 29 August 2007) for both direct comparison and the comparison using the same a priori profile, the CO concentrations in 28/8/2005 higher. The CO maps were generated using Kriging Interpolation technique. This interpolation technique produced high correlation coefficient, R2 and low root mean square error, RMS for CO. This study provided useful information for influence change of CO concentration on varies temperature.

  17. Full-Wave Radio Characterization of Ionospheric Modification at HAARP

    DTIC Science & Technology

    2015-07-26

    V. Belyey. The spatial features of the up- and downshifted maxima in stimulated electromagnetic emissions, Advances in Space Research, (05 2012...Full-Wave Radio Characterization of Ionospheric Modification at HAARP We have studied electrostatic and electromagnetic turbulence stimulated by...frequency, radio, full wave, plasma waves, plasma instabilites, remote sensing, electromagnetic emissions, antenna, radio imaging, descending layer REPORT

  18. LOFAR as an ionospheric probe

    NASA Astrophysics Data System (ADS)

    Gaussiran, T. L., II; Bust, G. S.; Garner, T. W.

    2004-12-01

    At the Low-Frequency Array (LOFAR)(Planet. Space Sci. (2004) these proceedings) frequencies (HF/VHF), extraterrestrial radiation experiences substantial propagation delay as it passes through the ionosphere. The adaptive calibration technique to be employed by LOFAR will use signals from many known bright radio sources in the sky to estimate and remove the effects of this delay. This technique will operate along many simultaneous lines of sight for each of the stations. Measurements will be made on time scales of seconds or shorter, and with accuracies corresponding to path length variations of 1 cm or less. Tomographic techniques can be used to invert the thousands of changing and independent total electron content (TEC) measurements produced by LOFAR into three-dimensional electron density specifications above the array. These specifications will measure spatial and time scales significantly smaller and faster than anything currently available. These specifications will be used to investigate small-scale ionospheric irregularities, equatorial plasma structures, and ionospheric waves. In addition, LOFAR will improve the understanding of the solar drivers of the ionosphere by simultaneously measuring the solar radio bursts and the TEC. Finally, LOFAR, which will be situated to observed the galactic plane, will make continuous, high-resolution observations of the low-latitude ionosphere, an important but under-observed region. This paper will look at LOFAR as an ionospheric probe including comparisons to other ionospheric probes as well as possible methods of operation to optimize ionospheric measurements.

  19. Millimeter Wave Moisture Sounder Feasibility Study: The Effect of Cloud and Precipitation on Moisture Retrievals.

    DTIC Science & Technology

    1985-03-08

    D-A162 231 MILLIMETER WAVE MOISTURE SOUNDER FEASIBILITY STUDY- THE i/1 EFFECT OF CLOUD A (U) ATMOSPHERIC AND ENVIRONMENTAL RESEARCH INC CAMBRIDGE MA...34 ,,; - -., ,..-.,- -, ,.. . : .,,- ,.. ,- - - , . .. .-. ,=, .-,o.. .- .-,o ,-N . ,.-,."...,- ,,, .. .,..; .. ,., .:°B,.. ’ AFGL-TR-85-0040 MILLIMETER WAVE MOISTURE SOUNDER FEASIBILITY STUDY: THE EFFECT OF...REPORT A PERIOD COVERED Millimeter Wave Moisture Sounder Feasibility Final Report Study: The Effect of Cloud and Precipitation 8 Aug 1984-7 Feb 1985 on

  20. Forecasting Space Weather in the Upper Atmosphere and Ionosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    2013-12-01

    The feasibility of performing meaningful forecasts of the state of the thermosphere and ionosphere depends on the time scales of interest. Whether accomplished using empirical models derived from climatological information, or using numerical models describing the physics and dynamics of the coupled system, the reality of any forecast is dependent on the specification of the initial state, and the knowledge of the parameters that will impact it in the future. The zero-time forecast, or nowcast, is eminently possible, and basic systems have been implemented operationally using data assimilation techniques. This is considerably more advanced with respect to the ionosphere, because there are more ionospheric data currently available. But a fully coupled thermosphere is crucial for accomplishing accurate ionospheric specification and forecast, because the ionosphere responds strongly to thermospheric drivers, and because the effects of changing thermospheric dynamics are persistent. The prospects for short term (less than an hour) forecasts are also good. The 30 to 90 minute delay between measurements near the Sun-Earth L1 saddle point, and the arrival of solar wind and interplanetary field perturbations at the magnetopause, can be exploited to predict the effects of geomagnetic disturbances on the thermosphere-ionosphere. Lower atmosphere meteorology fields are sufficiently known and change slowly on these time scales, as do solar irradiance drivers (except during flares) so the boundary conditions to full-physics numerical models can be specified. The initial state of the system can be effectively characterized by data assimilation models. Sophisticated physical models using efficient parallel algorithms are available. Therefore, there are no fundamental obstacles to implementation of short-term thermosphere-ionosphere forecasting, only programmatic or technical ones. On longer time scales, magnetospheric forecasting is contingent on meaningful prediction of the

  1. Value-added Impact from Future Geostationary Hyperspectral Infrared Sounder Observations on Hurricane Forecasts

    NASA Astrophysics Data System (ADS)

    Li, J.; Schmit, T. J.; Li, Z.; Zhu, F.; Lim, A.; Atlas, R. M.; John, P.

    2015-12-01

    Future geostationary (Geo) advanced InfraRed (IR) sounders have finer spatial, spectral, and temporal resolutions compared with the existing GOES sounders, providing much improved resolving power of atmospheric thermodynamic information. When quantitatively assessing the value-added impact from such instruments over the current sounding systems onboard the Low Earth Orbit (Leo) satellites, the real question is what is the optimal impact using the current assimilation/forecast systems. More specifically, will assimilation of more observations from Geo IR sounders with the current assimilation/forecast systems yield improved forecast as expected? And if so, how to assimilate the high temporal resolution Geo sounding information and what is the impact on forecasts? Taken tropical cyclone (TC) forecasting as an example, this study tries to address these questions through a quick regional Observing System Simulation Experiments (r-OSSE) study. The synthetic observations are simulated from the sample ECMWF T1279 nature run (NR) for Hurricane Sandy (2012), including RAOB, the Leo AIRS, and Geo AIRS. Various experiments were carried out using WRF 3.6.1 and GSI 3.3 to study the impact on Sandy track forecast. And the study shows that a) it is critical to assign an appropriate observational error (observation error covariance matrix - O matrix) in order to show improved positive impacts from Geo AIRS over Leo AIRS; b) cycling of 3/6-hourly shows improved positive impacts over none cycling, but hourly cycling does not show further improvement on forecasts among all experiments, and c) with thinning (120 ~ 240 km), the impacts have the following order: hourly > 3-hourly > 6-hourly > none cycling. These experiments indicate that while more observations may improve forecasts, much more observations are difficult to show further improvement with the current assimilation/forecast system configurations. There exists a tradeoff between the number of observations to be assimilated

  2. Formation and ascent of nonisothermal ionospheric and chromospheric bubbles

    SciTech Connect

    Genkin, L.G.; Erukhimov, L.M.; Myasnikov, E.N.; Shvarts, M.M.

    1987-11-01

    The influences of nonisothermicity on the dynamics of ionospheric and chromospheric bubbles is discussed. The possibility of the existence in the ionosphere of a recombination-thermal instability, arising from the temperature dependence of the coefficient of charge exchange between molecules and atomic ions, is shown, and its influence on the formation and evolution of equatorial bubbles is analyzed. It is shown that the formation and dynamics of bubbles may depend on recombination processes and gravity, while plasma heating (predominantly by vertical electric fields) leads to the deepening and preservation of bubbles as they move to greater altitudes. The hypothesis is advanced that the formation of bubbles may be connected with the ascent of clumps of molecules in ionospheric tornados.

  3. All Ionospheres are not Alike: Reports from other Planets

    NASA Technical Reports Server (NTRS)

    Nagy, Andrew F.; Cravens, Thomas E.; Waite, H. J., Jr.

    1995-01-01

    Our understanding of planetary ionospheres made some progress during the last four years. Most of this progress was due to new and/or improved theoretical models, although some new data were also obtained by direct and remote sensing observations. The very basic processes such as ionization, chemical transformations and diffusive as well as convective transports are analogous in all ionospheres; the major differences are the result of factors such as different neutral atmospheres, intrinsic magnetic field strength, distance from the Sun, etc. Improving our understanding of any of the ionospheres in our solar system helps in elucidating the controlling physical and chemical processes in all of them. New measurements are needed to provide new impetus, as well as guidance, in advancing our understanding and we look forward to such information in the years ahead.

  4. An overview of radar soundings of the martian ionosphere from the Mars Express spacecraft

    NASA Astrophysics Data System (ADS)

    Gurnett, D. A.; Huff, R. L.; Morgan, D. D.; Persoon, A. M.; Averkamp, T. F.; Kirchner, D. L.; Duru, F.; Akalin, F.; Kopf, A. J.; Nielsen, E.; Safaeinili, A.; Plaut, J. J.; Picardi, G.

    The Mars Express spacecraft carries a low-frequency radar called MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) that is designed to study the subsurface and ionosphere of Mars. In this paper, we give an overview of the ionospheric sounding results after approximately one year of operation in orbit around Mars. Several types of ionospheric echoes are commonly observed. These include vertical echoes caused by specular reflection from the horizontally stratified ionosphere; echoes from a second layer in the topside ionosphere, possibly associated with O+ ions; oblique echoes from upward bulges in the ionosphere; and a variety of other echoes that are poorly understood. The vertical echoes provide electron density profiles that are in reasonable agreement with the Chapman photo-equilibrium model of planetary ionospheres. On the dayside of Mars the maximum electron density is approximately 2 × 105 cm-3. On the nightside the echoes are often very diffuse and highly irregular, with maximum electron densities less than 104 cm-3. Surface reflections are sometimes observed in the same frequency range as the diffuse echoes, suggesting that small isolated holes exist in the nightside ionosphere, possibly similar to those that occur on the nightside of Venus. The oblique echoes arise from upward bulges in the ionosphere in regions where the crustal magnetic field of Mars is strong and nearly vertical. The bulges tend to be elongated in the horizontal direction and located in regions between oppositely directed arch-like structures in the crustal magnetic field. The nearly vertical magnetic field lines in the region between the arches are thought to connect into the solar wind, thereby allowing solar wind electrons to heat the lower levels of the ionosphere, with an attendant increase in the scale height and electron density.

  5. Scale Height variations with solar cycle in the ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Milan, Stephen E.; Hall, Benjamin E. S.; Cartacci, Marco; Radicella, Sandro M.; Blelly, Pierre-Louis

    2015-04-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on board the Mars Express spacecraft has been probing the topside of the ionosphere of Mars since June 2005, covering currently almost one solar cycle. A good knowledge of the behaviour of the ionospheric variability for a whole solar period is essential since the ionosphere is strongly dependent on solar activity. Using part of this dataset, covering the years 2005 - 2012, differences in the shape of the topside electron density profiles have been observed. These variations seem to be linked to changes in the ionospheric temperature due to the solar cycle variation. In particular, Mars' ionospheric response to the extreme solar minimum between end-2007 and end-2009 followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to internal origin of the magnetic field between both planets. Plasma parameters such as the scale height as a function of altitude, the main peak characteristics (altitude, density), the total electron content (TEC), the temperatures, and the ionospheric thermal pressures show variations related to the solar cycle. The main changes in the topside ionosphere are detected during the period of very low solar minimum, when ionospheric cooling occurs. The effect on the scale height is analysed in detail. In contrast, a clear increase of the scale height is observed during the high solar activity period due to enhanced ionospheric heating. The scale height variation during the solar cycle has been empirically modelled. The results have been compared with other datasets such as radio-occultation and retarding potential analyser data from old missions, especially in low solar activity periods (e.g. Mariner 4, Viking 1 and 2 landers), as well as with numerical modelling.

  6. Total ionospheric electron content calibration using SERIES GPS satellite data

    NASA Technical Reports Server (NTRS)

    Lanyi, G.

    1986-01-01

    The current status of the Deep Space Network advanced systems research into ionospheric calibration techniques, based on Global Positioning System (GPS) data is described. A GPS-based calibration system is planned to replace the currently used Faraday rotation method by 1989. The SERIES receiver system determines the differential group delay of signals transmitted at two different carrier frequencies. This differential delay includes an ionospheric component and a GPS transmitter offset. The transmitter offsets are different for each GPS satellite. Tests were conducted to assess the effect of the offsets on the ionospheric calibration accuracy. From the obtained data, the total electron content and GPS transmitter offsets are calculated by a least squares estimation method employing a local model of total ionospheric electron content. The end product is an estimation of the total ionospheric content for an arbitrary line-of-sight direction. For the presented polynomial fitting technique, the systematic error due to mismodeling is estimated to be approximately 6 x 10 to the 16th power el/sq m, while the formal error is approximately 2 x 10 to the 16th power el/sq m. The final goal is an error of 3 x 10 to the 16th power el/sq m (approximately 0.7 ns at 2.3 GHz).

  7. Ionospheric mid-latitude response to solar wind discontinuities

    NASA Astrophysics Data System (ADS)

    Munteanu, Costel; Mosna, Zbysek; Kouba, Daniel; Echim, Marius

    2013-04-01

    We have compiled a database of 356 discontinuities detected by both the Advanced Composition Explorer ACE) and Cluster satellites in the solar wind between 2001-2012 and analyzed their ionospheric response. Each discontinuity of the data base is defined by a change of at least 5 nT in less than 5 min in one or more components of the interplanetary magnetic field (IMF). The discontinuities are observed in January-April every year, when Cluster enters the solar wind. The ionospheric effects of solar wind discontinuities are investigated by checking the variations of critical frequencies foF2, the heights of the F layer and the ionospheric plasma dynamics recorded using ground measurement with a time resolution of 15 minutes from mid-latitude digisondes located in Czech Republic. The time delay between solar wind input and the ionospheric response is analyzed using the characteristics and the shape of the ionograms. The geoeffectiveness of the solar wind discontinuities is expressed as correlation between key plasma parameters (e,g, the solar wind velocity, magnetic jump across the discontinuity) and the ionospheric variations. Solar cycle effects are also discussed.

  8. The microwave limb sounder for the Upper Atmosphere Research Satellite

    NASA Technical Reports Server (NTRS)

    Waters, J. W.; Peckham, G. E.; Suttie, R. A.; Curtis, P. D.; Maddison, B. J.; Harwood, R. S.

    1988-01-01

    The Microwave Limb Sounder was designed to map the concentrations of trace gases from the stratosphere to the lower thermosphere, to improve understanding of the photochemical reactions which take place in this part of the atmosphere. The instrument will measure the intensity of thermal radiation from molecules in the atmosphere at frequencies corresponding to rotational absorption bands of chlorine monoxide, ozone, and water vapor. Molecular concentration profiles will be determined over a height range of 15 to 80 km (20 to 45 km for C10). The 57 deg inclination orbit proposed for the Upper Atmosphere Research Satellite will allow global coverage.

  9. GEOSTAR - a microwave sounder for GOES-R

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn; Wilson, William; Tanner, Alan

    2005-01-01

    The National Oceanic and Atmospheric Administration (NOAA) has for many years operated two weather satellite systems, the Polar-orbiting Operational Environmental Satellite system (POES), using low-earth orbiting (LEO) satellites, and the Geostationary Operational Environmental Satellite system (GOES), using geostationary earth orbiting (GEO) satellites. Similar systems are also operated by other nations. The POES satellites have been equipped with both infrared (IR) and microwave (MW) atmospheric sounders, which together make it possible to determine the vertical distribution of temperature and humidity in the troposphere even under cloudy conditions.

  10. Multiorder etalon sounder (MOES) development and test for balloon experiment

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.; Wnag, Jinxue; Wu, Jian

    1993-01-01

    The Fabry-Perot interferometer (FPI), with its high throughput and high spectral resolution has been used in the remote-sensing measurements of the earth's atmospheric composition, winds, and temperatures. The most recent satellite instruments include the Fabry-Perot interferometer flown on the Dynamics Explorer-2 (DE-2), the High Resolution Doppler Imager (HRDI), and the Cryogenic Limb Array Etalon Spectrometer (CLAES) flown on the Upper Atmosphere Research Satellite (UARS). These instruments measure the Doppler line profiles of the emission and absorption of certain atmospheric species (such as atomic oxygen) in the visible and infrared spectral region. The successful space flight of DE-FPI, HRDI, and CLAES on UARS demonstrated the extremely high spectral resolution and ruggedness of the etalon system for the remote sensing of earth and planetary atmospheres. Recently, an innovative FPI focal plane detection technique called the Circle-to-Line Interferometer Optical (CLIO) system was invented at the Space Physics Research Laboratory. The CLIO simplifies the FPI focal plane detection process by converting the circular rings or fringes into a linear pattern similar to that produced by a conventional spectrometer, while retaining the throughput advantage of the etalon interferometer. The combination of FPI and CLIO allows the development of more sensitive Fabry-Perot interferometers in the infrared for the remote sensing of the lower atmospheres of Earth and possibly other planets. The Multiorder Etalon Sounder (MOES), a combination of the rugged etalon and the CLIO, compares very favorably to other space-borne optical instruments in terms of performance versus complexity. The new instrument is expected to be rugged, compact, and very suitable for an operational temperature and moisture sounder. With this technique, the contamination of radiance measurements by emissions of other gases is also minimized. At the Space Physics Research Laboratory (SPRL), the MOES

  11. Improving Regional Forecast by Assimilating Atmospheric InfraRed Sounder (AIRS) Profiles into WRF Model

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung; Zavodsky, Brad; Jedlovec, Gary J.

    2009-01-01

    In data sparse regions, remotely-sensed observations can be used to improve analyses and produce improved forecasts. One such source comes from the Atmospheric InfraRed Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), represents one of the most advanced space-based atmospheric sounding systems. The purpose of this paper is to describe a procedure to optimally assimilate high resolution AIRS profile data into a regional configuration of the Advanced Research WRF (ARW) version 2.2 using WRF-Var. The paper focuses on development of background error covariances for the regional domain and background type, and an optimal methodology for ingesting AIRS temperature and moisture profiles as separate overland and overwater retrievals with different error characteristics. The AIRS thermodynamic profiles are derived from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm and contain information about the quality of each temperature layer. The quality indicators were used to select the highest quality temperature and moisture data for each profile location and pressure level. The analyses were then used to conduct a month-long series of regional forecasts over the continental U.S. The long-term impacts of AIRS profiles on forecast were assessed against verifying NAM analyses and stage IV precipitation data.

  12. Investigations of atmospheric dynamics using a CW Doppler sounder array

    NASA Technical Reports Server (NTRS)

    Rao, G. L.

    1974-01-01

    A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

  13. Characterising the Ionosphere (La caracterisation de l’ionosphere)

    DTIC Science & Technology

    2009-01-01

    Conclusions: Space weather storms have induced power cuts in the U.S.A., Europe and South Africa. Such events demand a regional and global risk analysis , a...region in particular. By the same token, the ionospheric plasma can escape to space (polar wind and auroral bulk upflows of ions with energy of a...ionospheric currents to which they connect. While most of the energy dissipated though Joule heating is associated with the large scale slowly varying

  14. Ionospheric plasma drift and structure studies at high and mid-latitudes. Volume 1. Final report, October 1990-October 1993

    SciTech Connect

    Reinisch, B.W.; Scali, J.L.; Dozois, C.; Crowley, G.

    1993-12-01

    Ground-based observations of the high latitude ionosphere with Digisonde sounders at Quaanaaq, Sondrestrom, Goose Bay, Argentina and Millstone Hill provide a description of the patch structure and the convection pattern in the polar cap. Correlation analysis of observed F-region plasma drifts with the orientation of the interplanetary magnetic field (measured by IMP8) lead to a new technique of deducing the signs of Bz and By from the measured drifts. Real time calculation of the plasma drift was successfully introduced at one of the Digisonde stations (Sondrestrom) providing the possibility of determining the IMF components in real time. Analysis of mid-latitude trough observation shows large westward velocities in the trough region. Digisonde data from Quaanaaq and DMSP F8 and F9 satellite data showed the development of the ionospheric polar hole.

  15. Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere

    SciTech Connect

    Liu Yu; Cao Jinxiang; Wang Jian; Zheng Zhe; Xu Liang; Du Yinchang

    2012-09-15

    A new approach for investigating ionosphere chemical depletion in the laboratory is introduced. Air glow discharge plasma closely resembling the ionosphere in both composition and chemical reactions is used as the artificially created ionosphere. The ionospheric depletion experiment is accomplished by releasing chemicals such as SF{sub 6}, CCl{sub 2}F{sub 2}, and CO{sub 2} into the model discharge. The evolution of the electron density is investigated by varying the plasma pressure and input power. It is found that the negative ion (SF{sub 6}{sup -}, CCl{sub 2}F{sub 2}{sup -}) intermediary species provide larger reduction of the electron density than the positive ion (CO{sub 2}{sup +}) intermediary species. The negative ion intermediary species are also more efficient in producing ionospheric holes because of their fast reaction rates. Airglow enhancement attributed to SF{sub 6} and CO{sub 2} releases agrees well with the published data. Compared to the traditional methods, the new scheme is simpler to use, both in the release of chemicals and in the electron density measurements. It is therefore more efficient for investigating the release of chemicals in the ionosphere.

  16. TEC disturbances during major Sudden Stratospheric Warmings in the mid-latitude ionosphere.

    NASA Astrophysics Data System (ADS)

    Polyakova, Anna; Voeykov, Sergey; Chernigovskaya, Marina; Perevalova, Natalia

    Using total electron content (TEC) global ionospheric maps, dual-frequency GPS receivers TEC data and MLS (Microwave Limb Sounder, EOS Aura) atmospheric temperature data the ionospheric disturbances during the strong sudden stratospheric warmings (SSWs) of 2008/2009 and 2012/2013 winters are investigated in Russia's Asia region. It is established that during the SSW maximum the midday TEC decrease and the night/morning TEC increase compared to quiet days are observed in the mid-latitude ionosphere. As a result it caused the decrease of the diurnal TEC variations amplitude of about two times in comparison with the undisturbed level. The analysis of TEC deviations from the background level during the SSWs has shown that deviations dynamics vary depending on the observation point position. Negative deviations of TEC are registered in the ionosphere above the region of maximum stratosphere heating (the region of the stratospheric circulation change) as well as above the anticyclone. On the contrary, TEC values increase compared to the quiet day's values above the stratosphere cyclone. It is shown that during maximum phase of a warming, and within several days after it the amplification of wave TEC variations intensity with periods of up to 60 min is registered in ionosphere. The indicated effects may be attributed to the vertical transfer of molecular gas from a stratospheric heating region to the thermosphere as well as to the increase in activity of planetary and gravity waves which is usually observed during strong SSWs. The study is supported by the RF President Grant of Public Support for RF Leading Scientific Schools (NSh-2942.2014.5), the RF President Grant No. MK-3771.2012.5 and RFBR Grant No. 12-05-00865_а.

  17. The Behm Acoustic Sounder for Airplanes with Reference to Its Accuracy

    NASA Technical Reports Server (NTRS)

    Schreiber, Ernest

    1930-01-01

    Relative altimetry is of great importance for increasing the safety in aerial transportation, because it makes possible safe flying at night, by poor visibility, and when landing. Among the instruments of this type is the Behm sounder, which operates on an acoustic principle. Acoustic altimetry in general and the Behn sounder, in particular, are covered in this report.

  18. Sounding rockets explore the ionosphere

    SciTech Connect

    Mendillo, M. )

    1990-08-01

    It is suggested that small, expendable, solid-fuel rockets used to explore ionospheric plasma can offer insight into all the processes and complexities common to space plasma. NASA's sounding rocket program for ionospheric research focuses on the flight of instruments to measure parameters governing the natural state of the ionosphere. Parameters include input functions, such as photons, particles, and composition of the neutral atmosphere; resultant structures, such as electron and ion densities, temperatures and drifts; and emerging signals such as photons and electric and magnetic fields. Systematic study of the aurora is also conducted by these rockets, allowing sampling at relatively high spatial and temporal rates as well as investigation of parameters, such as energetic particle fluxes, not accessible to ground based systems. Recent active experiments in the ionosphere are discussed, and future sounding rocket missions are cited.

  19. Ionospheric chemistry of NO(+)

    NASA Technical Reports Server (NTRS)

    Breig, E. L.; Hanson, W. B.; Hoffman, J. H.

    1984-01-01

    An investigation is described of the behavior of NO(+) in the daytime F region, with basic ion concentration measurements from the Atmosphere Explorer C satellite. The data set was acquired along select orbits at low latitudes and exhibits substantial variations in the NO(+) concentration, both along and between nearby orbits. An excellent consistency is demonstrated between these observations and current chemical equilibrium theory, in contrast to differences that have been reported for the related N2(+) ion. Large variations in the concurrently observed electron temperature permit a relevant comparison between different laboratory determinations of the dissociative recombination rate coefficient. Contributions to the NO(+) production from several secondary sources are also evaluated. Results strengthen the basis for the current theoretical ionospheric chemistry of NO(+) and establish important constraints on resolution of the difficulties with N2(+).

  20. Ionospheric scintillation studies

    NASA Technical Reports Server (NTRS)

    Rino, C. L.; Freemouw, E. J.

    1973-01-01

    The diffracted field of a monochromatic plane wave was characterized by two complex correlation functions. For a Gaussian complex field, these quantities suffice to completely define the statistics of the field. Thus, one can in principle calculate the statistics of any measurable quantity in terms of the model parameters. The best data fits were achieved for intensity statistics derived under the Gaussian statistics hypothesis. The signal structure that achieved the best fit was nearly invariant with scintillation level and irregularity source (ionosphere or solar wind). It was characterized by the fact that more than 80% of the scattered signal power is in phase quadrature with the undeviated or coherent signal component. Thus, the Gaussian-statistics hypothesis is both convenient and accurate for channel modeling work.

  1. GeoSTAR - A Microwave Sounder for Geostationary Satellites

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn; Wilson, William; Tanner, Alan; Gaier, Todd; Ruf, Chris; Piepmeier, Jeff

    2004-01-01

    GeoSTAR represents a new approach to microwave atmospheric sounding that is now under development. It has capabilities similar to sensors currently operating on low earth orbiting weather satellites but is intended for deployment in geostationary orbit - where it will complement future infrared sounders and enable all-weather temperature and humidity soundings and rain mapping. The required spatial resolution of 50 km or better dictates an aperture of 4 meters or more at a sounding frequency of 50 GHz, which is difficult to achieve with a real aperture system - this is the reason why it has until now not been possible to put a microwave sounder on a geostationary platform. GeoSTAR is instead based on a synthetic aperture imaging approach. Among the advantages of such a system are that there are no moving parts, and the size of the aperture is easily expandable to meet future needs. A ground based prototype of GeoSTAR is currently under development in an effort led by the Jet Propulsion Laboratory.

  2. Requirements for a Moderate-Resolution Infrared Imaging Sounder (MIRIS)

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Aumann, Hartmut H.; Gerber, Andrew J.; Kuai, Le; Gontijo, I.; DeLeon, Berta; Susskind, Joel; Iredell, Lena; Bajpai, Shyam

    2013-01-01

    The high cost of imaging and sounding from space warrants exploration of new methods for obtaining the required information, including changing the spectral band sets, employing new technologies and merging instruments. In some cases we must consider relaxation of the current capability. In others, we expect higher performance. In general our goal is to meet the VIIRS and CrIS requirements while providing the enhanced next generation capabilities: 1) Hyperspectral Imaging in the Vis/NIR bands, 2) High Spatial Resolution Sounding in the Infrared bands. The former will improve the accuracy of ocean color products, aerosols and water vapor, surface vegetation and geology. The latter will enable the high-impact achieved by the current suite of hyperspectral infrared sounders to be achieved by the next generation high resolution forecast models. We examine the spectral, spatial and radiometric requirements for a next generation system and technologies that can be applied from the available inventory within government and industry. A two-band grating spectrometer instrument called the Moderate-resolution Infrared Imaging Sounder (MIRIS) is conceived that, when used with the planned NASA PACE Ocean Color Instrument (OCI) will meet the vast majority of CrIS and VIIRS requirements in the all bands and provide the next generation capabilities desired. MIRIS resource requirements are modest and the Technology Readiness Level is high leading to the expectation that the cost and risk of MIRIS will be reasonable.

  3. Channel alignment and radiometry in hyperspectral atmospheric infrared sounders

    NASA Technical Reports Server (NTRS)

    Elliott, Denis A.; Aumanna, H. H.; Pagano, Thomas S.; Overoye, Kenneth R.; Schindler, Rudolf A.

    2005-01-01

    The Atmospheric Infrared Sounder (AIRS) is a hyper-spectral infrared sounder which covers the 3.7 to 15,4 micron region with 2378 spectral channels. The AIRS instrument specification called for spatial co-registration of all channels to better than 2% of the field of view. Pre-launch testing confirmed that this requirement was met, since the standard deviations in the centroids was about 1% of the 13.5 km IFOV in scan and 3% in track. Detailed analysis of global AIRS data show that the typical scene gradient in 10 micron window channels is about I .3K/km rms. The way these gradients, which are predominantly caused by clouds, manifest themselves in the data depends on the details of the instrument design and the way the spectral channels are used in the data analysis, AIRS temperature and moisture retrievals use 328 of the 2378 channels from 17 independent arrays. As a result, the effect of the boresight misalignment averages to zero mean. Any increase in the effective noise is less than 0.2K. Also, there is no discernable performance degradation of products at the 45 km spatial resolution in the presence of partially cloudy scenes with up to 80% cloudiness. Single pixel radiometric differences between channels with boresight alignment differences can be appreciable and can affect scientific investigations on a single 15km footprint scale, particularly near coastlines, thunderstorms and surface emissivity inhomogeneities.

  4. The International Reference Ionosphere: Model Update 2016

    NASA Astrophysics Data System (ADS)

    Bilitza, Dieter; Altadill, David; Reinisch, Bodo; Galkin, Ivan; Shubin, Valentin; Truhlik, Vladimir

    2016-04-01

    The International Reference Ionosphere (IRI) is recognized as the official standard for the ionosphere (COSPAR, URSI, ISO) and is widely used for a multitude of different applications as evidenced by the many papers in science and engineering journals that acknowledge the use of IRI (e.g., about 11% of all Radio Science papers each year). One of the shortcomings of the model has been the dependence of the F2 peak height modeling on the propagation factor M(3000)F2. With the 2016 version of IRI, two new models will be introduced for hmF2 that were developed directly based on hmF2 measurements by ionosondes [Altadill et al., 2013] and by COSMIC radio occultation [Shubin, 2015], respectively. In addition IRI-2016 will include an improved representation of the ionosphere during the very low solar activities that were reached during the last solar minimum in 2008/2009. This presentation will review these and other improvements that are being implemented with the 2016 version of the IRI model. We will also discuss recent IRI workshops and their findings and results. One of the most exciting new projects is the development of the Real-Time IRI [Galkin et al., 2012]. We will discuss the current status and plans for the future. Altadill, D., S. Magdaleno, J.M. Torta, E. Blanch (2013), Global empirical models of the density peak height and of the equivalent scale height for quiet conditions, Advances in Space Research 52, 1756-1769, doi:10.1016/j.asr.2012.11.018. Galkin, I.A., B.W. Reinisch, X. Huang, and D. Bilitza (2012), Assimilation of GIRO Data into a Real-Time IRI, Radio Science, 47, RS0L07, doi:10.1029/2011RS004952. Shubin V.N. (2015), Global median model of the F2-layer peak height based on ionospheric radio-occultation and ground-based Digisonde observations, Advances in Space Research 56, 916-928, doi:10.1016/j.asr.2015.05.029.

  5. The worldwide ionospheric data base

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter

    1989-01-01

    The worldwide ionospheric data base is scattered over the entire globe. Different data sets are held at different institutions in the U.S., U.S.S.R., Australia, Europe, and Asia. The World Data Centers on the different continents archive and distribute part of the huge data base; the scope and cross section of the individual data holdings depend on the regional and special interest of the center. An attempt is made to pull together all the strings that point toward different ionospheric data holdings. Requesters are provided with the information about what is available and where to get it. An attempt is also made to evaluate the reliability and compatibility of the different data sets based on the consensus in the ionospheric research community. The status and accuracy of the standard ionospheric models are also discussed because they may facilitate first order assessment of ionospheric effects. This is a first step toward an ionospheric data directory within the framework of NSSDC's master directory.

  6. Application of the Dopplionogram to Doppler-sorted interferometry measurements of ionospheric drift velocity

    NASA Astrophysics Data System (ADS)

    Parkinson, M. L.; Breed, A. M.; Dyson, P. L.; Morris, R. J.

    1999-07-01

    The Dopplionogram was developed as a method of displaying Doppler shifts along the frequency axis of ionograms recorded using B-mode soundings of the Dynasonde, an early type of HF digital ionosonde. The basic idea of recording Doppler shifts in an ionogram format is applied and extended to the Doppler velocity mode of the Digisonde Portable Sounder-4 (DPS-4), a related and more recent type of digital ionosonde. In order to describe our mode of operation a Dopplionogram is redefined to mean a set of stepped-frequency soundings that yields a set of ionospheric Doppler shifts particular to the chosen transmission frequencies. Extension of the technique to include Doppler-sorted interferometry (DSI) analysis of the Doppler spectra facilitates a detailed analysis of ionospheric velocity variations in time and group height. This revitalized approach to DSI should prove useful for the study of ionospheric dynamics for which knowledge of the height profile of electric currents, drift velocity, and neutral winds is required. The technique is demonstrated using measurements of polar cap plasma winds obtained with a DPS-4 located at Casey, Antarctica (66.3°S, 110.5°E).

  7. Altitude Variation of the Plasmapause Signature in the Main Ionospheric Trough

    NASA Technical Reports Server (NTRS)

    Grebowsky, Joseph M.; Benson, Robert F.; Webb, Phillip A.; Truhlik, Vladimir; Bilitza, Dieter

    2009-01-01

    The projection of the plasmapause magnetic-field lines to low altitudes, where the light-ion chemistry is dominated by O(+), tends to occur near the minimum electron density in the main (midlatitude) electron density trough at night. With increasing attitude in the trough, where H(+) emerges as the dominant iota on the low-latitude boundary, we have found cases where the plasmapause field lines are located on the sharp low-Latitude side of the trough as expected if this topside ionosphere H(+) distribution varies in step with the plasmapause gradient in the distant plasmasphere. These conclusions are based on near-equatorial crossings of the plasmapause (corresponding to the steep gradient in the dominant species H(+) by the Explorer-45 satellite as determined from electric-field measurements by Maynard and Cauffman in the early 1970s and ISIS-2 ionospheric topside-sounder measurements. The former data have now been converted to digital form and made available at http://nssdcftp.gsfc.nasa.gov. The latter provide samples of nearly coincident observations of ionospheric main trough crossings near the same magnetic-field lines of the Explorer 45-determined equatorial plasmapause. The ISIS-2 vertical electron density profiles are used to infer where the F-region transitions from an O(+) to a H(+) dominated plasma through the main trough boundaries.

  8. Acoustic disturbance at ionospheric heights caused by the MILL RACE explosion

    SciTech Connect

    Rickel, D.G.; Simons, D.J.

    1982-01-01

    The principal objective of the Los Alamos National Laboratory in the MILL RACE experiment was to measure the over-head ionospheric response due to the MILL RACE explosion. Such a measurement enables one to test computer models designed to quantitatively predict ionospheric disturbances caused by known sources. The emphasis of the models has been directed at calculating effects on rf propagation associated with the predicted ionospheric disturbances. Consequently vertical incidence phase sounding measurements of a well-characterized source provide a direct and sensitive test of the computer models and, for this reason, a vertical incidence phase sounder was located 3300 meters to the west of the MILL RACE ground zero. Another area of interest is the development of an understanding of the atmospheric response to known sources at distances where the acoustic response no longer dominates. Such an undertaking requires measurements at these remote points. Deployment of a bistatic sounding network enabled the investigation of this area of interest. Results are reported.

  9. Evidence of Convective Redistribution of Carbon Monoxide in Aura Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) Observations

    NASA Technical Reports Server (NTRS)

    Manyin, Michael; Douglass, Anne; Schoeberl, Mark

    2010-01-01

    Vertical convective transport is a key element of the tropospheric circulation. Convection lofts air from the boundary layer into the free troposphere, allowing surface emissions to travel much further, and altering the rate of chemical processes such as ozone production. This study uses satellite observations to focus on the convective transport of CO from the boundary layer to the mid and upper troposphere. Our hypothesis is that strong convection associated with high rain rate regions leads to a correlation between mid level and upper level CO amounts. We first test this hypothesis using the Global Modeling Initiative (GMI) chemistry and transport model. We find the correlation is robust and increases as the precipitation rate (the strength of convection) increases. We next examine three years of CO profiles from the Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) instruments aboard EOS Aura. Rain rates are taken from the Tropical Rainfall Measuring Mission (TRMM) 3B-42 multi-satellite product. Again we find a correlation between mid-level and upper tropospheric CO, which increases with rain rate. Our result shows the critical importance of tropical convection in coupling vertical levels of the troposphere in the transport of trace gases. The effect is seen most clearly in strong convective regions such as the Inter-tropical Convergence Zone.

  10. Science Goals and Mission Objectives of Nasa's Laser Atmospheric Wind Sounder Program

    NASA Technical Reports Server (NTRS)

    Baker, Wayman E.

    1992-01-01

    Knowledge of the global wind field is widely recognized as fundamental to advancing our understanding and prediction of the total Earth system. Yet, because wind profiles are primarily measured by land-based rawinsondes, the oceanic areas (covering three quarters of the Earth's surface) and many regions of the less developed southern hemisphere land areas are poorly observed. The gap between our requirements for wind data and their availability continues to widen. For example, as faster computers become available to model the atmosphere with ever increasing resolution and sophistication, our ability to model the atmosphere will be hampered by a lack of data, particularly wind profiles. In order to address this important deficiency in wind observations, NASA plans to construct the Laser Atmospheric Wind Sounder (LAWS) instrument, with deployment tentatively scheduled between 2002 and 2005 as part of NASA's Earth Observing System (EOS) mission. Addressed here is the importance of wind measurements for advancing our understanding and prediction of the total Earth System. The current characteristics of the LAWS instrument under study are also summarized.

  11. Geo-STAR: A Geostationary Microwave Sounder for the Future

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn H.; Brown, S. T.; Dinardo, S. J.; Gaier, T. C.; Kangaslahti, P. P.; Tanner, A. B.

    2007-01-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a 'Decadal Survey' of NASA Earth Science activities1. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported

  12. Ionospheric Profiling using GPS/MET Data

    NASA Technical Reports Server (NTRS)

    Hajj, George; Romans, Larry

    1996-01-01

    A report on ionospheric profiling using GPS and MET data is presented. A description of the GPS occultation technique, some examples of GPS/MET data products, the data processing system and a preliminary validation of ionospheric profiles is discussed.

  13. Ionospheric disturbances in north eastern region of Asia during sudden stratospheric warming in January-February 2008

    NASA Astrophysics Data System (ADS)

    Kurkin, Vladimir; Medvedeva, Irina; Orlov, Igor; Pirog, Olga; Shpynev, Boris; Chernigovskaya, Marina

    This paper presents an investigation of the subauroral and mid-latitude ionosphere variations in the north eastern region of Asia from 18-th January until 17-th February, 2008. We used the data from network of vertical sounding ionosondes and Irkutsk incoherent scatter (IS) radar. To study small scales disturbances the observations using Irkutsk chirp-sounder and IS radar were conducted every 1 minute on 24-hour basis for 30 days. Vertical sounding stations operated in standard regime. To identify the stratospheric warming events the Berlin Meteorological University data (http://strat-www.met.fu-berlin.de) on stratospheric warming at standard isobaric levels and the atmospheric temperature height profiles measured by the Microwave Limb Sounder (MLS) aboard the EOS Aura spacecraft were used. Spectrums of multi-scale variations were derived from the data obtained during the prolonged experiment. We used the spectral analysis based on a modified Fourier transform with varying upper limit. The possible reasons of the ionospheric disturbances and their intensity spatial distribution are discussed. This work was supported by Russian Foundation for Basic Research (grant 08-05-00658).

  14. Cross-Track Infrared Sounder Science Data Record Pre-launch Calibration and On-Orbit Validation Plans

    NASA Astrophysics Data System (ADS)

    Hagan, D. E.; Bingham, G. E.; Predina, J.; Gu, D.; Sabet-Peyman, F.; Wang, C.; de Amici, G.; Plonski, M.; Farrow, S. V.; Hohn, J.; Esplin, M.; Zavyalov, V.; Fish, C. S.; Glumb, R.; Wells, S.; Suwinski, L.; Strong, J.; Behrens, C.; Kilcoyne, H.; Feeley, J.; Kratz, G.; Tremblay, D. A.

    2009-12-01

    The Cross-Track Infrared Sounder (CrIS) together with the Advanced Technology Microwave Sounder will provide retrievals of atmospheric moisture and temperature profiles for the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The NPOESS is the next generation of low Earth orbiting weather and climate satellites managed by the tri-agency Integrated Program Office, which includes the Department of Commerce, Department of Defense and the National Aeronautics and Space Administration. The CrIS is a Fourier-transform Michelson interferometer covering the spectral range of 3.9 to 15.4 microns (650 to 2550 wavenumbers) developed by ITT under contract to Northrop Grumman Aerospace Systems. The first deployment of the CrIS (Flight Model 1) is scheduled for 2010 on the NPOESS Preparatory Project (NPP) satellite, an early instrument risk reduction component of the NPOESS mission. The analysis and data results from comprehensive TVAC testing of the CrIS FM1 sensor demonstrate a very accurate radiometric and spectral calibration system. We describe instrument performance parameters, and the end-to-end plans and analysis tools for on-orbit verification of sensor characteristics and validation of the SDR radiance products.

  15. Stratospheric CH3CN from the UARS Microwave Limb Sounder

    NASA Astrophysics Data System (ADS)

    Livesey, Nathaniel J.; Waters, Joe W.; Khosravi, Rashid; Brasseur, Guy P.; Tyndall, Geoffrey S.; Read, William G.

    CH3CN in the stratosphere has been measured by the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS), providing the first global CH3CN dataset. The MLS observations are in broad agreement with past high and midlatitude observations of CH3CN, although concentrations are a little larger than previously observed. In the tropics, where CH3CN has not up to now been measured, a persistent ‘peak’ in the profiles is seen around 22 hPa, which may be evidence of a tropical stratospheric CH3CN source. Comparisons are made with the NCAR SOCRATES model, including runs having an artificial tropical stratospheric CH3CN source.

  16. Determination of cloud parameters from infrared sounder data

    NASA Technical Reports Server (NTRS)

    Yeh, H.-Y. M.

    1984-01-01

    The World Climate Research Programme (WCRP) plan is concerned with the need to develop a uniform global cloud climatology as part of a broad research program on climate processes. The International Satellite Cloud Climatology Project (ISCCP) has been approved as the first project of the WCRP. The ISCCP has the basic objective to collect and analyze satellite radiance data to infer the global distribution of cloud radiative properties in order to improve the modeling of cloud effects on climate. Research is conducted to explore an algorithm for retrieving cloud properties by utilizing the available infrared sounder data from polar-orbiting satellites. A numerical method is developed for computing cloud top heights, amount, and emissivity on the basis of a parameterized infrared radiative transfer equation for cloudy atmospheres. Theoretical studies were carried out by considering a synthetic atmosphere.

  17. Mechanical Description of the Mars Climate Sounder Instrument

    NASA Technical Reports Server (NTRS)

    Jau, Bruno M.

    2008-01-01

    This paper introduces the Mars Climate Sounder (MCS) Instrument of the Mars Reconnaissance Orbiter (MRO) spacecraft. The instrument scans the Martian atmosphere almost continuously to systematically acquire weather and climate observations over time. Its primary components are an optical bench that houses dual telescopes with a total of nine channels for visible and infrared sensing, and a two axis gimbal that provides pointing capabilities. Both rotating joints consist of an integrated actuator with a hybrid planetary/harmonic transmission and a twist cap section that enables the electrical wiring to pass through the rotating joint. Micro stepping is used to reduce spacecraft disturbance torques to acceptable levels while driving the stepper motors. To ensure survivability over its four year life span, suitable mechanical components, lubrication, and an active temperature control system were incorporated. Some life test results and lessons learned are provided to serve as design guidelines for actuator parts and flex cables.

  18. Satellite Sounder Data Assimilation for Improving Alaska Region Weather Forecast

    NASA Technical Reports Server (NTRS)

    Zhu, Jiang; Stevens, E.; Zavodsky, B. T.; Zhang, X.; Heinrichs, T.; Broderson, D.

    2014-01-01

    Data assimilation has been demonstrated very useful in improving both global and regional numerical weather prediction. Alaska has very coarser surface observation sites. On the other hand, it gets much more satellite overpass than lower 48 states. How to utilize satellite data to improve numerical prediction is one of hot topics among weather forecast community in Alaska. The Geographic Information Network of Alaska (GINA) at University of Alaska is conducting study on satellite data assimilation for WRF model. AIRS/CRIS sounder profile data are used to assimilate the initial condition for the customized regional WRF model (GINA-WRF model). Normalized standard deviation, RMSE, and correlation statistic analysis methods are applied to analyze one case of 48 hours forecasts and one month of 24-hour forecasts in order to evaluate the improvement of regional numerical model from Data assimilation. The final goal of the research is to provide improved real-time short-time forecast for Alaska regions.

  19. Slow Z-mode radiation from sounder-accelerated electrons

    NASA Astrophysics Data System (ADS)

    James, H. G.

    2004-12-01

    Quasi-electrostatic Z-mode waves created by the transmitting part of the OEDIPUS-C payload were measured on the receiving part at 1200 m distance. Solutions of the complete electromagnetic dispersion relation for a hot magnetoplasma reveal, however, that there is no solution that provides direct ray paths along the transmitter-receiver separation direction with the observed signal group delays. An interpretive model is therefore proposed in which sounder-accelerated electrons (SAE) radiate incoherently as they spiral along the magnetic field direction in the general direction of the receiving subpayload. Test-particle theory combined with the hot-plasma dispersion solution is used to predict the total electric field for previously reported SAE flux levels. It is found that voltage levels measured on the receiving dipoles have about the same order of magnitude as the predicted ones.

  20. Ionospheric electron density perturbations during the 7-10 March 2012 geomagnetic storm period

    NASA Astrophysics Data System (ADS)

    Belehaki, Anna; Kutiev, Ivan; Marinov, Pencho; Tsagouri, Ioanna; Koutroumbas, Kostas; Elias, Panagiotis

    2017-02-01

    From 7 to 10 March 2012 a series of magnetospheric disturbances caused perturbations in the ionospheric electron density. Analyzing the interplanetary causes in each phase of this disturbed period, in comparison with the total electron content (TEC) disturbances, we have concluded that the interplanetary solar wind controls largely the ionospheric response. An interplanetary shock detected at 0328UT on 7 March caused the formation of prompt penetrating electric fields in the dayside that transported plasma from the near-equatorial region to higher in attitudes and latitudes forming a giant plasma fountain which is part of the so-called dayside ionospheric super-fountain. The super-fountain produces an increase in TEC which is the dominant effect at middle latitude, masking the effect of the negative storm. Simultaneously, inspecting the TEC maps, we found evidence for a turbulence in TEC propagating southward probably caused by large scale travelling ionospheric disturbances (LSTIDs) linked to auroral electrojet intensification. On 8 March, a magnetospheric sudden impulse at 1130UT accompanied with strong pulsations in all interplanetary magnetic field (IMF) components and with northward Bz component during the growth phase of the storm. These conditions triggered a pronounced directly driven substorm phase during which we observe LSTID. However, the analysis of DMSP satellite observations, provided with strong evidence for Sub-Auroral Polarization Streams (SAPS) formation that erode travelling ionospheric disturbances (TID) signatures. The overall result of these mechanisms can be detected in maps of de-trended TEC, but it is difficult to identify separately each of the sources of the observed perturbations, i.e. auroral electrojet activity and LSTIDs, super-fountain and SAPS. In order to assess the capability of the ionospheric profiler called Topside Sounder Model - assisted Digisonde (TaD model) to detect such perturbations in the electron density, electron

  1. The International Reference Ionosphere - Climatological Standard for the Ionosphere

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter

    2006-01-01

    The International Reference Ionosphere (IRI) a joint project of URSI and COSPAR is the defacto standard for a climatological specification of ionospheric parameters. IRI is based on a wide range of ground and space data and has been steadily improved since its inception in 1969 with the ever-increasing volume of ionospheric data and with better mathematical descriptions of the observed global and temporal variation patterns. The IRI model has been validated with a large amount of data including data from the most recent ionospheric satellites (KOMPSAT, ROCSAT and TIMED) and data from global network of ionosondes. Several IRI teams are working on specific aspects of the IRI modeling effort including an improved representation of the topside ionosphere with a seamless transition to the plasmasphere, a new effort to represent the global variation of F2 peak parameters using the Neural Network (NN) technique, and the inclusion of several additional parameters in IRI, e.g., spread-F probability and ionospheric variability. Annual IRI workshops are the forum for discussions of these efforts and for all science activities related to IRI as well as applications of the IRI model in engineering and education. In this paper I will present a status report about the IRI effort with special emphasis on the presentations and results from the most recent IRI Workshops (Paris, 2004; Tortosa, 2005) and on the most important ongoing IRI activities. I will discuss the latest version of the IRI model, IRI-2006, highlighting the most recent changes and additions. Finally, the talk will review some of the applications of the IRI model with special emphasis on the use for radiowave propagation studies and communication purposes.

  2. Joule Heating as a Signature of Magnetosphere-Ionosphere-Thermosphere Coupling

    NASA Astrophysics Data System (ADS)

    Ceren Kalafatoglu Eyiguler, Emine; Kaymaz, Zerefsan

    2016-07-01

    Since its first proposal by Birkeland in the early 1900s, the link between magnetosphere and ionosphere (M-I) has been immensely studied but there are still great variety of unsolved problems ranging from how to correctly balance the field aligned current (FAC) closure in the ionosphere to the resulting interactions between ions and neutrals in the ionosphere, and how the ionospheric conductivity and neutral wind control the M-I feedback to the mapping of the ionospheric regions to the magnetotail. It is now well known that during magnetically disturbed periods, the energy deposited to the magnetosphere by the solar wind is partitioned mainly between three domains: the ring current, ionosphere (via auroral particle precipitation and Joule heating) and the plasmoid release in the magnetotail. It is previously found that large part of this transferred energy is in the form of Joule heating which is the increase in ion-neutral collisions due to the increased energy input. However, Joule heating is also affected by the enhanced neutral wind motion during geomagnetic storms and substorms. Thus, it is one of the key manifestations of the M-I-T coupling. In this talk, we first give a through review of the present studies and recent advancements in the M-I-T research area then show the link between the magnetosphere and ionosphere by investigating the activity-time Joule heating variations as well as paying special attention to the neutral wind effects on Joule heating.

  3. Assimilative modeling of ionospheric dynamics for nowcasting of HF propagation channels in the presence of TIDs

    NASA Astrophysics Data System (ADS)

    Nickisch, L. J.; Fridman, Sergey; Hausman, Mark; Kraut, Shawn; Zunich, George

    2016-03-01

    The ionospheric data assimilation algorithm called GPS Ionospheric Inversion (GPSII; pronounced "gypsy") has been extended and employed to model the dynamic ionosphere, including medium-scale traveling ionospheric disturbances (MS-TIDs). MS-TIDs are characterized by periods of 10-30 min. GPSII can assimilate many forms of ionospheric-related data, including ionogram data and GPS L1/L2 beacon data. For this present effort, GPSII was extended to assimilate propagation time delay, integrated Doppler shift, and angle-of-arrival (AoA) measurements of HF transmissions from known reference points (KRPs). GPSII applies a regularization technique that constrains the solver to find the smoothest 3-D ionosphere model that still reproduces the input data to within their respective errors of measurement. A companion paper documents the development of the assimilation capability for KRPs. In this paper we show test results of the model's performance in reproducing measured AoA variations in the presence of medium-scale traveling ionospheric disturbances (MS-TIDs) using near vertical incidence skywave data collected at White Sands Missile Range by the Intelligence Advanced Research Projects Activity HFGeo Program Government team. We find that using three KRPs within approximately 50 km of reference/check/nonassimilated transmitters, we can reproduce the measured AoAs of the nonassimilated transmitters to within 1.9° with 90% confidence even in the presence of highly dynamic MS-TIDs.

  4. A study of the Ionospheric electron density profile with FORMOSAT-3/COSMIC observation data

    NASA Astrophysics Data System (ADS)

    Chou, Min-Yang; Tsai, Ho-Fang; Lin, Chi-Yen; Lee, I.-Te; Lin, Charles; Liu, Jann-Yenq

    2015-04-01

    The GPS Occultation Experiment payload onboard FORMOSAT-3/COSMIC microsatellite constellation is capable of scanning the ionospheric structure by the radio occultation (RO) technique to retrieve precise electron density profiles since 2006. Due to the success of FORMOSAT-3/COSMIC, the follow-on mission, FORMOSAT-7/COSMIC-2, is to launch 12 microsatellites in 2016 and 2018, respectively, with the Global Navigation Satellite Systems (GNSS) RO instrument onboard for tracking GPS, Galileo and/or GLONASS satellite signals and to provide more than 8,000 RO soundings per day globally. An overview of the validation of the FORMOSAT-3/COSMIC ionospheric profiling is given by means of the traditional Abel transform through bending angle and total electron content (TEC), while the ionospheric data assimilation is also applied, based on the Gauss-Markov Kalman filter with the International Reference Ionosphere model (IRI-2007) and global ionosphere map (GIM) as background model, to assimilate TEC observations from FORMOSAT-3/COSMIC. The results shows comparison of electron density profiles from Abel inversion and data assimilation. Furthermore, an observing system simulation experiment is also applied to determine the impact of FORMOSAT-7/COSMIC-2 on ionospheric weather monitoring, which reveals an opportunity on advanced study of small spatial and temporal variations in the ionosphere.

  5. Ionospheric Profiles from Ultraviolet Remote Sensing

    DTIC Science & Technology

    1997-09-30

    The long-term goal of this project is to obtain ionospheric profiles from ultraviolet remote sensing of the ionosphere from orbiting space platforms... Remote sensing of the nighttime ionosphere is a more straightforward process because of the absence of the complications brought about by daytime

  6. Low-latitude ionospheric effects on SBAS

    NASA Astrophysics Data System (ADS)

    Arenas, J.; Sardón, E.; Sainz, A.; Ochoa, B.; Magdaleno, S.

    2016-06-01

    Satellite-based augmentation systems (SBAS) provide augmentation to Global Navigation Satellite Systems (GNSS) users in three areas: (1) broadcasting accurate corrections to GNSS satellite ephemeris, (2) providing a real-time empirical ionospheric model in the service area, and (3) providing integrity information in the form of estimates of the confidence of the ephemeris corrections and ionospheric delays. Ionospheric effects on SBAS are twofold: (a) the input data used by the SBAS will be affected by ionospheric effects, and (b) the more perturbed the ionosphere is, the more difficult it will be to provide accurate and reliable ionospheric information to the users. The ionosphere at low latitudes presents larger variability and more intense phenomena than at midlatitudes. Therefore, SBAS providing service to low-latitude regions will be more affected than those at other latitudes. From the different low-latitude ionospheric effects, this paper will focus on those having the largest impact on SBAS, which are total electron content temporal and spatial gradients, ionospheric scintillations, and depletions. This paper will present the impact of these effects on EGNOS (European Global Navigation Overlay System), the European SBAS. Although EGNOS can be considered as a midlatitude SBAS, it has to provide coverage down to rather low latitudes, so sometimes low-latitude ionospheric effects are observed in the EGNOS data. It will be shown how EGNOS performs under nominal conditions and how its performance is degraded when low-latitude ionospheric phenomena occur. Real EGNOS data affected by low-latitude ionospheric phenomena will be used.

  7. Doppler sounder observations of trade winds and sea breezes along the African west coast near 34 ° S, 19 ° E

    NASA Astrophysics Data System (ADS)

    Jury, Mark; Spencer-Smith, Garth

    1988-09-01

    Summer weather conditions along the west coast of Africa near 34 ° S, 18 ° E are investigated using doppler acoustic sounder profiles. Case studies were selected from a two-year record to form composite analyses over the diurnal cycle. The SE trade wind exhibited a low level jet at the level of the temperature inversion due to a sharp reversal in the thermal wind vector aloft. Mean wind speeds reached 14 m s-1 just before midnight as the surface and upper inversions strengthened. Seabreezes were categorised by the supporting gradient wind and found to have mean depths of 400 m, speeds of over 6 m s-1 at the 200 m level, and advance/retreat times of 09 hr and 16 20 hr. During seabreezes and weak on-shore gradient flow conditions, the thermal internal boundary layer (TIBL) was monitored with sounder transects in the first 12 km of the coastal zone. The growth height was observed to be 1:20 in the first 5 km and 1:50 farther inland. The sounder climatology, together with surface network and aerial survey results, illustrate the four-dimensional characteristics of trade winds and seabreezes near Cape Town.

  8. A Satellite Mission Concept to Study Thermosphere-Ionosphere Coupling

    NASA Astrophysics Data System (ADS)

    Pedersen, T. R.; Zesta, E.; Huang, C. Y.; Lin, C. S.; Marcos, F. A.; Roddy, P. A.; Ballenthin, J. O.; Sutton, E. K.; Cooke, D. L.

    2010-12-01

    A great number of space-based assets needed for Earth monitoring, research, and communications are used by a variety of agencies. Many of these assets orbit at altitudes within the upper thermosphere and ionosphere. At such altitudes the orbit of satellites can be greatly affected by the neutral atmosphere, whose dynamics are strongly driven by interactions with the ionosphere and ultimately by geospace phenomena like geomagnetic storms. Maintenance of the space catalogue and protection of our space-based assets requires fundamental understanding of this region of space and the coupling between the thermosphere and ionosphere. The TICOPS (Thermosphere Ionosphere Coupling and Orbit Prediction System) mission concept aims to achieve exactly this understanding through key measurements and advancement of models. TICOPS is a constellation of satellites to directly measure ALL the quantities in the satellite drag equation, enabling (1) immediate significant improvement in nowcasts and forecasts of atmospheric density, winds and composition; and (2) input to physics-based data assimilative models which will form the next generation products used in drag prediction. TICOPS consists of 3 satellites, two at high altitude (500-600km), I-COPS1 and 2, measuring incoming energy input, the third, T-COPS, at low altitude (~300km) measuring the thermospheric response. The mission goals are accomplished through 4 specific experiments: (1) Remote measurements of thermospheric neutral winds and validation, (2) In-situ thermospheric probe, (3) Energy input distribution over the thermosphere, and (4) Satellite drag coefficients.

  9. Ionospheric ion temperature forecasting in multiples of 27 days

    NASA Astrophysics Data System (ADS)

    Sojka, Jan J.; Schunk, Robert W.; Nicolls, Michael J.

    2014-03-01

    The ionospheric variability found at auroral locations is usually assumed to be unpredictable. The magnetosphere, which drives this ionospheric variability via storms and substorms, is at best only qualitatively describable. In this study we demonstrate that over a 3 year period, ionospheric variability observed from Poker Flat, Alaska, has, in fact, a high degree of long-term predictability. The observations used in this study are (a) the solar wind high speed stream velocity measured by the NASA Advanced Composition Explorer satellite, used to define the corotating interaction region (CIR), and (b) the ion temperature at 300 km altitude measured by the National Science Foundation Poker Flat Incoherent Scatter Radar over Poker Flat, Alaska. After determining a seasonal and diurnal climatology for the ion temperature, we show that the residual ion temperature heating events occur synchronously with CIR-geospace interactions. Furthermore, we demonstrate examples of ion temperature forecasting at 27, 54, and 81 days. A rudimentary operational forecasting scenario is described for forecasting recurrence 27 days ahead for the CIR-generated geomagnetic storms. These forecasts apply specifically to satellite tracking operations (thermospheric drag) and emergency HF-radio communications (ionospheric modifications) in the polar regions. The forecast is based on present-day solar and solar wind observations that can be used to uniquely identify the coronal hole and its CIR. From this CIR epoch, a 27 day forecast is then made.

  10. Chemical releases in the ionosphere

    NASA Technical Reports Server (NTRS)

    Davis, T. N.

    1979-01-01

    The study of the interaction between the atmosphere, ionosphere and magnetosphere is identified as a major task worthy of pursuit. The present review demonstrates the major contributions to this complex problem already made by active experiments involving the injection of chemicals and energetic electron beams into the atmosphere, ionosphere and magnetosphere. Through the use of chemical releases, it has been possible to investigate a number of quantities including high-altitude winds and electric fields, the detailed configurations of the geomagnetic field within the ionosphere and the magnetosphere, as well as the propagation of energetic particle beams and their interaction with natural neutral and ionized constituents of the high atmosphere. So far, virtually all of this effort has been accomplished using rockets. In the future, it is obvious that satellite platforms will play a greater role, both in making injections and in observing their effects.

  11. Distribution functions and statistical parameters that may be used to characterize limb sounders gravity wave climatologies in the stratosphere

    NASA Astrophysics Data System (ADS)

    Alexander, P.; Luna, D.; de la Torre, A.; Schmidt, T.

    2015-08-01

    The number of gravity wave (GW) activity climatologies in the stratosphere started to increase more than 10 years ago since the appearance of large amounts of limb and nadir satellite sounders data. There have been very few discussions regarding the adequate statistical description of GW activity in terms of a distribution function and its parameters. We put forward the question whether a general statistical functional representation adaptable to the characteristics of GW activity in diverse geographic regions and seasons exists. Here we approach this issue for two different types of limb sounders and in particular we try to find out which parameters may represent at best the climatological features. We study results for a region close to the Patagonian Andes and their prolongation in the Antarctic Peninsula, which is well-known for the generation by topography of intense stratospheric GW, specially during winter and spring. Global Positioning System (GPS) radio occultation (RO) records presently provide over 2000 profiles per day. We used 5 years of COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) mission GPS RO data, which supplied almost 150,000 retrievals for our study. Three different distribution functions have been approached to describe the GW activity climatologies: gaussian, log-normal and gamma. The latter function has not been used in previous work. It has been shown here that it is a competitive option to the log-normal distribution. In addition, its use allows not only to quantify the GW activity level of each climatology in the stratosphere, but also to find out the number of significant modes that essentially determine it. Alternative parameters to the mean like the median may be used to characterize the climatologies. The use of the median may exhibit advantages in cases where the presence of spurious large GW activity measurements are suspected in GPS RO data. The mean is equally suitable to establish GW activity

  12. LWS Investigation of Middle-Latitude Topside Ionospheric Vertical Electron-Density Profiles

    NASA Astrophysics Data System (ADS)

    Benson, R. F.; Grebowsky, J. M.; Webb, P. A.

    2005-05-01

    A Living With a Star (LWS) Targeted Research and Technology (TR&T) proposal has been selected to determine the dependence of the mid-latitude topside ionospheric electron-density (Ne) altitude distributions on long-term solar-cycle variations and short-term solar-wind and magnetic disturbances. The main focus is on Ne profiles from the height of the ionospheric Ne maximum to ~3,000 km as deduced from ISIS (International Satellites for Ionospheric Studies) topside-sounder data. These data, obtained over an 18-year time interval, can be used to investigate secular changes in the topside Ne profiles, which reflect altitude changes in plasma temperature and ion composition, over more than a solar cycle. In addition to providing average distributions the data, which extend from the O+ dominated high-altitude F region to the H+ dominated plasmasphere, provide a unique framework for delineating the altitude dependence of mid-latitude ionospheric structures associated with the plasmapause, plasmaspheric tails and Storm Enhanced Densities (SEDs). The approach used is to determine the locations of mid-latitude O+/H+ transition altitudes by fitting the topside Ne profiles with modeled H+ and O+ profiles that have the base electron temperature and temperature gradient at 400 km as variables. The investigation makes use of existing topside Ne profiles obtained from 1960's manual scaling of 35-mm film-format ionograms, available from ftp://nssdcftp.gsfc.nasa.gov/, and profiles deduced from digital topside ionograms available from http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html.

  13. On the determination of the effect of horizontal ionospheric gradients on ranging errors in GNSS positioning

    NASA Astrophysics Data System (ADS)

    Danilogorskaya, Ekaterina A.; Zernov, Nikolay N.; Gherm, Vadim E.; Strangeways, Hal J.

    2016-12-01

    An alternative approach to the traditionally employed method is proposed for treating the ionospheric range errors in transionospheric propagation such as for GNSS positioning or satellite-borne SAR. It enables the effects due to horizontal gradients of electron density (as well as vertical gradients) in the ionosphere to be explicitly accounted for. By contrast with many previous treatments, where the expansion of the solution for the phase advance is represented as the series in the inverse frequency powers and the main term of the expansion corresponds to the true line-of-sight distance from the transmitter to the receiver, in the alternative technique the zero-order term is the rigorous solution for a spherically layered ionosphere with any given vertical electron density profile. The first-order term represents the effects due to the horizontal gradients of the electron density of the ionosphere, and the second-order correction appears to be negligibly small for any reasonable parameters of the path of propagation and its geometry for VHF/UHF frequencies. Additionally, an "effective" spherically symmetric model of the ionosphere has been introduced, which accounts for the major contribution of the horizontal gradients of the ionosphere and provides very high accuracy in calculations of the phase advance.

  14. International Reference Ionosphere: Plasma densities - Status 1988

    NASA Technical Reports Server (NTRS)

    Rawer, K.; Bilitza, D.

    1990-01-01

    An account is given of the changes proposed in 1988 for the International Reference Ionosphere electron density profile, as well as the status of their implementation. The fully analytical profile function under development for the entire ionosphere can be achieved with a linear combination of several LAY functions. Although four LAY functions are required to describe the density features of the middle ionosphere, three LAY functions suffice to reproduce electron densities in both the topside ionosphere and lower ionosphere. Attention is given to the way in which the LAY parameters are computationally derivable from characteristic profile points.

  15. Investigation of ionospheric effects on SAR Interferometry (InSAR): A case study of Hong Kong

    NASA Astrophysics Data System (ADS)

    Zhu, Wu; Ding, Xiao-Li; Jung, Hyung-Sup; Zhang, Qin; Zhang, Bo-Chen; Qu, Wei

    2016-08-01

    Synthetic Aperture Radar Interferometry (InSAR) has demonstrated its potential for high-density spatial mapping of ground displacement associated with earthquakes, volcanoes, and other geologic processes. However, this technique may be affected by the ionosphere, which can result in the distortions of Synthetic Aperture Radar (SAR) images, phases, and polarization. Moreover, ionospheric effect has become and is becoming further significant with the increasing interest in low-frequency SAR systems, limiting the further development of InSAR technique. Although some research has been carried out, thorough analysis of ionospheric influence on true SAR imagery is still limited. Based on this background, this study performs a thorough investigation of ionospheric effect on InSAR through processing L-band ALOS-1/PALSAR-1 images and dual-frequency Global Positioning System (GPS) data over Hong Kong, where the phenomenon of ionospheric irregularities often occurs. The result shows that the small-scale ionospheric irregularities can cause the azimuth pixel shifts and phase advance errors on interferograms. Meanwhile, it is found that these two effects result in the stripe-shaped features in InSAR images. The direction of the stripe-shaped effects keep approximately constant in space for our InSAR dataset. Moreover, the GPS-derived rate of total electron content change index (ROTI), an index to reflect the level of ionospheric disturbances, may be a useful indicator for predicting the ionospheric effect for SAR images. This finding can help us evaluate the quality of SAR images when considering the ionospheric effect.

  16. HF Radio Wave Production of Artificial Ionospheres

    NASA Astrophysics Data System (ADS)

    Carlson, Herbert

    In 1993 it was predicted that artificial ionospheres would be produced by high power HF radio waves, once HF transmitters approached a GWatt ERP. When that threshold was very recently achieved, such production was indeed detected and published at two high latitude high power HF facilities. Here we review: the first-principles logic behind that prediction, which aspects of such production are critically dependent on magnetic latitude, and which aspects of such production depend only on physical parameters independent of latitude. These distinctions follow directly from decomposition of the problem of ionization production into its components of: radio-wave propagation, wave-particle interactions, electron transport, and quantitative elastic/inelastic cross-sections. We outline this analysis to show that, within the context of early observations, the production of ionization is inevitable, and only a question of competing instability thresholds, and scale of ionization production. This illustrates complimentary aeronomy and plasma physics to advance understanding of both.

  17. Development and initial assessment of a new land index for microwave humidity sounder cloud detection

    NASA Astrophysics Data System (ADS)

    Qin, Zhengkun; Zou, Xiaolei

    2016-02-01

    This paper describes a new quality control (QC) scheme for microwave humidity sounder (MHS) data assimilation. It consists of a cloud detection step and an O-B (i.e., differences of brightness temperatures between observations and model simulations) check. Over ocean, cloud detection can be carried out based on two MHS window channels and two Advanced Microwave Sounding Unit-A (AMSU-A) window channels, which can be used for obtaining cloud ice water path (IWP) and liquid water path (LWP), respectively. Over land, cloud detection of microwave data becomes much more challenging due to a much larger emission contribution from land surface than that from cloud. The current MHS cloud detection over land employs an O-B based method, which could fail to identify cloudy radiances when there is mismatch between actual clouds and model clouds. In this study, a new MHS observation based index is developed for identifying MHS cloudy radiances over land. The new land index for cloud detection exploits the large variability of brightness temperature observations among MHS channels over different clouds. It is shown that those MHS cloudy radiances that were otherwise missed by the current O-B based QC method can be successfully identified by the new land index. An O-B check can then be employed to the remaining data after cloud detection to remove additional outliers with model simulations deviated greatly from observations. It is shown that MHS channel correlations are significantly reduced by the newly proposed QC scheme.

  18. Data Assimilation and Regional Forecasts Using Atmospheric InfraRed Sounder (AIRS) Profiles

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung; Zavodsky, Bradley; Jedlovec, Gary

    2009-01-01

    In data sparse regions, remotely-sensed observations can be used to improve analyses, which in turn should lead to better forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), provides temperature and moisture profiles with an accuracy comparable to that of radiosondes. The purpose of this paper is to describe a procedure to optimally assimilate AIRS thermodynamic profiles--obtained from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm-into a regional configuration of the Weather Research and Forecasting (WRF) model using WRF-Var. The paper focuses on development of background error covariances for the regional domain and background field type, a methodology for ingesting AIRS profiles as separate over-land and over-water retrievals with different error characteristics, and utilization of level-by-level quality indicators to select only the highest quality data. The assessment of the impact of the AIRS profiles on WRF-Var analyses will focus on intelligent use of the quality indicators, optimized tuning of the WRF-Var, and comparison of analysis soundings to radiosondes. The analyses will be used to conduct a month-long series of regional forecasts over the continental U.S. The long-tern1 impact of AIRS profiles on forecast will be assessed against verifying radiosonde and stage IV precipitation data.

  19. The Geostationary Remote Infrared Pollution Sounder (GRIPS): measurement of the carbon gases from space

    NASA Astrophysics Data System (ADS)

    Schoeberl, M.; Dickerson, R.; Marshall, B. T.; McHugh, M.; Fish, C.; Bloom, H.

    2013-09-01

    Climate change and air quality are the most pressing environmental issues of the 21st century. Despite decades of research, the sources and sinks of key greenhouse gases remain highly uncertain [IPCC1] making quantitative predictions of atmospheric composition and their impacts. The Geostationary Remote Infrared Pollution Sounder (GRIPS) is a multi-purpose instrument designed to reduce uncertainty associated with atmospheric radiative forcing. GRIPS will measure will measure greenhouse gases and aerosols - two of the most important elements in the earth's radiation budget. GRIPS will observe carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), - the carbon gases, nitrous oxide (N2O), water vapor and aerosols with unprecedented precision through the atmosphere. The GRIPS instrument uses gas filter correlation radiometry (GFCR) to detect reflected and thermal IR radiation to detect the gases and the reflected solar radiation in the visible and short-wave infrared bands for aerosols. GRIPS is designed to have sensitivity down to the Earth's surface at ~2-8km nadir resolution. GRIPS can resolve CO2, CO, and CH4 anomalies in the planetary boundary layer and the free troposphere to quantify lofting, diurnal variations and longrange transport. With repeated measurements throughout the day GRIPS can maximize the number of cloud free measurements determining biogenic and anthropogenic sources, sinks, and fluxes. GRIPS is highly complementary to the Orbiting Carbon Observatory, OCO-2, the geostationary Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Advanced Baseline Imager (ABI) and other existing and planned missions.

  20. Atmospheric, Cloud, and Surface Parameters Retrieved from Satellite Ultra-spectral Infrared Sounder Measurements

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Yang, Ping; Schluessel, Peter; Strow, Larrabee

    2007-01-01

    An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. This physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multivariable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. This retrieval algorithm is applied to the MetOp satellite Infrared Atmospheric Sounding Interferometer (IASI) launched on October 19, 2006. IASI possesses an ultra-spectral resolution of 0.25 cm(exp -1) and a spectral coverage from 645 to 2760 cm(exp -1). Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI measurements are obtained and presented.

  1. Data Assimilation and Regional Forecasts using Atmospheric InfraRed Sounder (AIRS) Profiles

    NASA Technical Reports Server (NTRS)

    Zabodsky, Brad; Chou, Shih-Hung; Jedlovec, Gary J.

    2009-01-01

    In data sparse regions, remotely-sensed observations can be used to improve analyses, which in turn should lead to better forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which, together with the Advanced Microwave Sounding Unit (AMSU), provides temperature and moisture profiles with an accuracy comparable to that of radionsondes. The purpose of this poster is to describe a procedure to optimally assimilate AIRS thermodynamic profiles, obtained from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm, into a regional configuration of the Weather Research and Forecasting (WRF) model using WRF-Var. The poster focuses on development of background error covariances for the regional domain and background field type, a methodology for ingesting AIRS profiles as separate over-land and over-water retrievals with different error characteristics, and utilization of level-by-level quality indicators to select only the highest quality data. The assessment of the impact of the AIRS profiles on WRF-Var analyses will focus on intelligent use of the quality indicators, optimized tuning of the WRF-Var, and comparison of analysis soundings to radiosondes. The analyses are used to conduct a month-long series of regional forecasts over the continental U.S. The long-term impact of AIRS profiles on forecast will be assessed against NAM analyses and stage IV precipitation data.

  2. Airborne Deployment and Calibration of Microwave Atmospheric Sounder on 6U CubeSat

    NASA Astrophysics Data System (ADS)

    Padmanabhan, S.; Brown, S. T.; Lim, B.; Kangaslahti, P.; Russell, D.; Stachnik, R. A.

    2015-12-01

    To accurately predict how the distribution of extreme events may change in the future we need to understand the mechanisms that influence such events in our current climate. Our current observing system is not well-suited for observing extreme events globally due to the sparse sampling and in-homogeneity of ground-based in-situ observations and the infrequent revisit time of satellite observations. Observations of weather extremes, such as extreme precipitation events, temperature extremes, tropical and extra-tropical cyclones among others, with temporal resolution on the order of minutes and spatial resolution on the order of few kms (<10 kms), are required for improved forecasting of extreme weather events. We envision a suite of low-cost passive microwave sounding and imaging sensors on CubeSats that would work in concert with traditional flagship observational systems, such as those manifested on large environmental satellites (i.e. JPSS,WSF,GCOM-W), to monitor weather extremes. A 118/183 GHz sensor would enable observations of temperature and precipitation extremes over land and ocean as well as tropical and extra-tropical cyclones. This proposed project would enable low cost, compact radiometer instrumentation at 118 and 183 GHz that would fit in a 6U Cubesat with the objective of mass-producing this design to enable a suite of small satellites to image the key geophysical parameters needed to improve prediction of extreme weather events. We take advantage of past and current technology developments at JPL viz. HAMSR (High Altitude Microwave Scanning Radiometer), Advanced Component Technology (ACT'08) to enable low-mass, low-power high frequency airborne radiometers. In this paper, we will describe the design and implementation of the 118 GHz temperature sounder and 183 GHz humidity sounder on the 6U CubeSat. In addition, we will discuss the maiden airborne deployment of the instrument during the Plain Elevated Convection at Night (PECAN) experiment. The

  3. A Review of Ionospheric Scintillation Models.

    PubMed

    Priyadarshi, S

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

  4. Hyperspectral Microwave Atmospheric Sounder (HyMAS) Architecture and Design Accommodations

    NASA Technical Reports Server (NTRS)

    Hilliard, Lawrence; Racette, Paul; Blackwell, William; Galbraith, Christopher; Thompson, Erik

    2013-01-01

    The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term "hyperspectral microwave" is used to indicate an all-weather sounding that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earth s atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions. The simulations proposed for HyMAS 118/183-GHz system should yield surface precipitation rate and water path retrievals for small hail, soft hail, or snow pellets, snow, rainwater, etc. with accuracies comparable to those of the Advanced Technology Microwave Sounder. Further improvements in retrieval methodology (for example, polarization exploitation) are expected. The CoSMIR instrument is a packaging concept re-used on HyMAS to ease the integration features of the scanhead. The HyMAS scanhead will include an ultra-compact Intermediate Frequency Processor (IFP) module that is mounted inside the door to improve thermal management. The IFP is fabricated with materials made of Low-Temperature Co-fired Ceramic (LTCC) technology integrated with detectors, amplifiers, A/D conversion and data aggregation. The IFP will put out 52 channels of 16 bit data comprised of 4-9 channel data streams for temperature profiles and 2-8 channel streams for water vapor. With the limited volume of the existing CoSMIR scanhead and new HyMAS front end components, the HyMAS team at Goddard began preliminary layout work inside the new drum. Importing and re-using models of the shell, the scan head computer

  5. Hyperspectral Microwave Atmospheric Sounder (HyMAS) architecture and design accommodations

    NASA Astrophysics Data System (ADS)

    Hilliard, L.; Racette, P.; Blackwell, W.; Galbraith, C.; Thompson, E.

    The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term “ hyperspectral microwave” is used to indicate an all-weather sounding that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earth's atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions. The simulations proposed for HyMAS 118/183-GHz system should yield surface precipitation rate and water path retrievals for small hail, soft hail, or snow pellets, snow, rainwater, etc. with accuracies comparable to those of the Advanced Technology Microwave Sounder. Further improvements in retrieval methodology (for example, polarization exploitation) are expected. The CoSMIR instrument is a packaging concept re-used on HyMAS to ease the integration features of the scanhead. The HyMAS scanhead will include an ultra-compact Intermediate Frequency Processor (IFP) module that is mounted inside the door to improve thermal management. The IFP is fabricated with materials made of Low-Temperature Co-fired Ceramic (LTCC) technology integrated with detectors, amplifiers, A/D conversion and data aggregation. The IFP will put out 52 channels of 16 bit data comprised of 4 - 9 channel data streams for temperature profiles and 2-8 channel streams for water vapor. With the limited volume of the existing CoSMIR scanhead and new HyMAS front end components, the HyMAS team at Goddard began preliminary layout work inside the new drum. Importing and re-using models of the shell, the s- an head

  6. Recent microwave sounder observations from aircraft during the HS3 field campaign

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, B.; Brown, S. E.

    2014-12-01

    The High Altitude MMIC Sounding Radiometer (HAMSR) is a microwave sounder similar to but more capable and accurate than current satellite microwave sounders. Since 2010 it has operated on NASA's Global Hawk UAVs and has been participating in the multiyear Hurricane and Severe Storm Sentinel (HS3) hurricane campaign. We present recent results from HS3, including analysis of the thermodynamic and precipitation structure in and around tropical storm systems sampled during HS3. Copyright 2014 California Institute of Technology. Government sponsorship acknowledged.

  7. Limits of Precipitation Detection from Microwave Radiometers and Sounders

    NASA Astrophysics Data System (ADS)

    Munchak, S. J.; Skofronick-Jackson, G.; Johnson, B. T.

    2012-04-01

    The Global Precipitation Measurement (GPM) mission will unify and draw from numerous microwave conical scanning imaging radiometers and cross-track sounders, many of which already in operation, to provide near real-time precipitation estimates worldwide at 3-hour intervals. Some of these instruments were designed for primary purposes unrelated to precipitation remote sensing. Therefore it is worthwhile to evaluate the strengths and weaknesses of each set of channels with respect to precipitation detection to fully understand their role in the GPM constellation. The GPM radiometer algorithm will use an observationally-based Bayesian retrieval with common databases of precipitation profiles for all sensors. Since these databases are still under development and will not be truly complete until the GPM core satellite has completed at least one year of dual-frequency radar observations, a screening method based upon retrieval of non-precipitation parameters related to the surface and atmospheric state is used in this study. A cost function representing the departure of modeled radiances from their observed values plus the departure of surface and atmospheric parameters from the TELSEM emissivity atlas and MERRA reanalysis is used as an indicator of precipitation. Using this method, two datasets are used to evaluate precipitation detection: One year of matched AMSR-E and AMSU-B/MHS overpasses with CloudSat used as validation globally; and SSMIS overpasses over the United States using the National Mosaic and QPE (NMQ) as validation. The Heidke Skill Score (HSS) is used as a metric to evaluate detection skill over different surfaces, seasons, and across different sensors. Non-frozen oceans give the highest HSS for all sensors, followed by bare land and coasts, then snow-covered land and sea ice. Negligible skill is present over ice sheets. Sounders tend to have higher skill than imagers over complex surfaces (coast, snow, and sea ice), whereas imagers have higher skill

  8. Validation of the Radiometric Stability of the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Aumann, H. H.; Elliott, D.; Strow, L. L.

    2012-01-01

    It has been widely accepted that an infrared sounder in low polar orbit is capable of producing climate quality data, if the spectral brightness temperatures have instrumental trends of less than 10 mK/yr. Achieving measurement stability at this level is not only very demanding of the design of the instrument, it is also pushes the state of art of measuring on orbit what stability is actually achieved. We discuss this using Atmospheric Infrared Sounder (AIRS) L1B data collected between 2002 and 2011. We compare the L1B brightness temperature observed in cloud filtered night tropical ocean spectra (obs) to the brightness temperature calculated based on the known surface emissivity, temperature and water vapor profiles from the ECMWF ReAnalysis (ERA) and the growth rates of CO2, N2O and Ozone. The trend in (obs-calc) is a powerful tool for the evaluation of the stability of the 2378 AIRS channels. We divided the channels into seven classes: All channels which sound in the stratosphere (at pressure levels below 150 hPa), 14 micron CO2 sounding, 4 micron CO2 P-branch sounding, 4 micron CO2 R-branch sounding, water vapor sounding, shortwave surface sounding and longwave surface sounding. The peak in the weighting function at 1050 hPa separates sounding and surface channels. The boundary between shortwave and longwave is 5 microns. Except for the stratosphere sounding channels, the remaining six groups have (obs-calc) trends of less than 20 mK/yr. The longwave surface channels have trends of 2 mK/yr, significantly less than the 8 mK/yr trend seem in the shortwave window channels. Based on the design of the instrument, trends within a group of channels should be the same. While the longwave and shortwave trends are less than the canonical 10 mK/yr, the larger trend in the shortwave channels could be an artifact of using the pre-launch determined calibration coefficients. This is currently under evaluation. The trend in (obs-calc) for the non-surface sounding channels, in

  9. Magnetospheric-ionospheric Poynting flux

    NASA Technical Reports Server (NTRS)

    Thayer, Jeffrey P.

    1994-01-01

    Over the past three years of funding SRI, in collaboration with the University of Texas at Dallas, has been involved in determining the total electromagnetic energy flux into the upper atmosphere from DE-B electric and magnetic field measurements and modeling the electromagnetic energy flux at high latitudes, taking into account the coupled magnetosphere-ionosphere system. This effort has been very successful in establishing the DC Poynting flux as a fundamental quantity in describing the coupling of electromagnetic energy between the magnetosphere and ionosphere. The DE-B satellite electric and magnetic field measurements were carefully scrutinized to provide, for the first time, a large data set of DC, field-aligned, Poynting flux measurement. Investigations describing the field-aligned Poynting flux observations from DE-B orbits under specific geomagnetic conditions and from many orbits were conducted to provide a statistical average of the Poynting flux distribution over the polar cap. The theoretical modeling effort has provided insight into the observations by formulating the connection between Poynting's theorem and the electromagnetic energy conversion processes that occur in the ionosphere. Modeling and evaluation of these processes has helped interpret the satellite observations of the DC Poynting flux and improved our understanding of the coupling between the ionosphere and magnetosphere.

  10. Calibrating for Ionospheric Phase Delays

    NASA Technical Reports Server (NTRS)

    Macdoran, P. F.

    1985-01-01

    Technique determines ionospheric phase delay on real-time universally applicable basis in terms of electrons per meter squared by coherently modulating two L-band carrier frequencies received from two Global Positioning System satelites. Two pseudorandom number sequences cross-correlated to derive delay time.

  11. Global measurements of wind fields using the Laser Atmospheric Wind Sounder (LAWS) on the Earth Observing System (EOS)

    NASA Technical Reports Server (NTRS)

    Fitzjarrald, Daniel E.

    1988-01-01

    The technology for measuring global wind fields in space by the Laser Atmospheric Wind Sounder (LAWS) to be flown on the Earth Observing System (EOS) is discussed. Studies initiated by NASA to determine the feasibility of using Doppler lidar from a platform in space to measure the wind globally have shown the general feasibility of the technique and have identified the technological problems that need to be resolved. Among the lidar systems being evaluated, CO2 coherent detection lidar is given special consideration. A comprehensive research program, the Global Backscatter Experiment, has been established to study global distribution of naturally occurring atmospheric aerosols that provide signal return at the wavelengths used by the techniques under consideration. Wind profiles from space will provide essential information for advancing the skill of numerical weather prediction, furthering the present knowledge of the large-scale atmospheric circulation and climate dynamics, and of global biogeochemical and hydrologic cycles.

  12. Multiparametric study of polar ionosphere on both hemispheres

    NASA Astrophysics Data System (ADS)

    D'Angelo, Giulia; Alfonsi, Lucilla; Spogli, Luca; Cesaroni, Claudio; Sgrigna, Vittorio

    2016-04-01

    The polar ionosphere is a complex system in which several actors concur to establish the observed medium. Indeed the coupling between the interplanetary magnetic field and the earth magnetic field determines a high degree of complexity of the polar ionosphere, which is directly exposed to the variations of the solar wind. This configuration results in a strong sensitivity of the polar ionosphere to the perturbation phenomena caused by solar events which may result in a wide variety of spatial and temporal dimensions of the plasma electron density irregularities. Polar ionospheric irregularities may seriously jeopardize performance and reliability level of the navigation and positioning technological systems, such as GPS or the nascent Galileo. Therefore, knowledge of the physical state of the upper atmosphere ionized layers becomes essential to predict and mitigate events that may affect the use of modern technology, causing economic damage and, in severe cases, even jeopardizing the safety of human beings. In this context, a careful and thorough investigation that covers a wide range of geospatial different disturbances, observed in circumterrestrial space and on the ground, can provide the necessary basis for a real advance of the current knowledge. In this frame, the aim of this work is to contribute to the study of the effects of perturbation induced by the Sun on the polar ionosphere of both the hemispheres, through the analysis and interpretation of the measures available before, during and after the occurrence of an event of disturbance. We propose a multiparametric approach, that combines the information derived from measurements acquired by ground-based and space-based stations, to have a broad spectrum of information necessary to characterize the ionospheric disturbances on different time scales (from milliseconds to days) and spatial scales (from millimetres to hundreds meters/kilometres). The period chosen for this study is the entire month of March

  13. IONOTOMO: A new approach for ionospheric tomography using OTH radar

    NASA Astrophysics Data System (ADS)

    Roy, Corinna; Occhipinti, Giovanni; Boschi, Lapo; Moliné, Jean-Philippe

    2013-04-01

    Most of the recent methods in ionospheric tomography are based on the inversion of the Total Electron Content (TEC) measured by ground-based GPS receivers [e.g., Garcia et al. 2008]. As a consequence of the high frequency of the GPS, the electron density structure is principally well reconstructed at the F2 region, where the ionosphere reaches the maximum of ionization, neglecting the lower ionosphere. Here, we develop a new 3D ionospheric tomography method based on the full analysis of over-the-horizon (OTH) radar data. Previous studies in ionospheric tomography by OTH radar (Fridman and Fridman, 1994; Ruelle and Landeau, 1994; Landeau et al., 1997; Fridman, 1998) are all based on the inversion of the leading edge echo curve, consequently an important amount of valuable information present in the data is necessarily neglected. To overcome this limit, we set up a new method, based on the ray-tracing tool TDR [Occhipinti, 2006], to invert the propagation time of electromagnetic waves emitted by monostatic OTH radars. The major advance of our methodology is taking into account, numerically and jointly, not only the speed variation of EM wave induced by the electron density variation (solved analytically with a linear inversion) but also the perturbation in the raypath (nonlinear numerical method). As the present problem is an ill posed problem we calculate the matrix inversion numerically, using a regularisation method (Tikhonov, 1963). We determine the best regularisation parameter using the Lcurve method (Hansen, 2000). We present here the originality and the advantage of our method with a full set of synthetic benchmark highlighting the sensitivity of our tomography to the plasma heterogeneities. Some preliminary test on real data will be presented with a full coverage over Europe. Indeed, the ionospheric tomography by OTH radar, jointly with GPS, could open new exciting perspective in the plasma density estimation with a good resolution to the entire ionosphere

  14. Ionospheric corrections to precise time transfer using GPS

    NASA Technical Reports Server (NTRS)

    Snow, Robert W.; Osborne, Allen W., III; Klobuchar, John A.; Doherty, Patricia H.

    1994-01-01

    The free electrons in the earth's ionosphere can retard the time of reception of GPS signals received at a ground station, compared to their time in free space, by many tens of nanoseconds, thus limiting the accuracy of time transfer by GPS. The amount of the ionospheric time delay is proportional to the total number of electrons encountered by the wave on its path from each GPS satellite to a receiver. This integrated number of electrons is called Total Electron Content, or TEC. Dual frequency GPS receivers designed by Allen Osborne Associates, Inc. (AOA) directly measure both the ionospheric differential group delay and the differential carrier phase advance for the two GPS frequencies and derive from this the TEC between the receiver and each GPS satellite in track. The group delay information is mainly used to provide an absolute calibration to the relative differential carrier phase, which is an extremely precise measure of relative TEC. The AOA Mini-Rogue ICS-4Z and the AOA TurboRogue ICS-4000Z receivers normally operate using the GPS P code, when available, and switch to cross-correlation signal processing when the GPS satellites are in the Anti-Spoofing (A-S) mode and the P code is encrypted. An AOA ICS-Z receiver has been operated continuously for over a year at Hanscom AFB, MA to determine the statistics of the variability of the TEC parameter using signals from up to four different directions simultaneously. The 4-channel ICS-4Z and the 8-channel ICS-4000Z, have proven capabilities to make precise, well calibrated, measurements of the ionosphere in several directions simultaneously. In addition to providing ionospheric corrections for precise time transfer via satellite, this dual frequency design allows full code and automatic codeless operation of both the differential group delay and differential carrier phase for numerous ionospheric experiments being conducted. Statistical results of the data collected from the ICS-4Z during the initial year of

  15. A Case Study of the Density Structure over a Vertical Magnetic Field Region in the Martian Ionosphere

    NASA Astrophysics Data System (ADS)

    Duru, F.; Gurnett, D. A.; Morgan, D. D.; Dieval, C.; Pisa, D.; Lundin, R. N. A.

    2014-12-01

    One of the discoveries made by Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on the Mars Express spacecraft is the existence of magnetically controlled structures in the ionosphere of Mars, which result in irregularities in the ionospheric electron density contours. These irregularities lead in turn to oblique echoes, which show up as hyperbola-shaped features on the plots of echo intensity measured by MARSIS as a function of altitude and universal time. The study of a hyperbola-shaped feature observed in a pass over an isolated region of strong crustal magnetic field shows that this kind of feature can be associated with a plasma cavity in the upper ionosphere and a corresponding density enhancement in the lower levels of the ionosphere. At the location where the hyperbola-shaped echo is observed, the electron and ion fluxes measured by ASPERA-3 at the location of the spacescraft are depleted and the local electron density from MARSIS shows a small decrease, as well. However, the peak ionospheric density obtained by MARSIS remote sounding shows a clear increase as Mars Express passes over the same region. We conclude that through the open magnetic field lines, the electrons are accelerated downward and ions are accelerated upward in a manner similar to the field-line driven auroral acceleration at Earth. This heating due to precipitating electrons causes a bulge at the altitude of the main ionosphere, which in turn leads to a hyperbola shaped echo, and loss of ionospheric plasma at high altitudes.

  16. The energetics of Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Roboz, A.; Nagy, A. F.

    1994-02-01

    We have developed a comprehensive model to study the dynamics and energetics of the ionosphere of Titan. We solved the one-dimensional, time-dependent, coupled continuity and momentum equations for several ion species, together with single ion and electron energy equations, in order to calculate density, velocity, and temperature profiles. Calculations were carried out for several cases corresponding to different local times and configurations of the Titan-Saturn system. In our model the effects of horizontal magnetic fields were assumed to be negligible, except for their effect on reducing the electron and ion thermal conductivities and inhibiting vertical transport in the subram region. The ionospheric density peak was found to be at an altitude of about 1100 km, in accordance with earlier model calculations. The ionosphere is chemically controlled below an altitude of about 1500 km. Above this level, ion densities differ significantly from their chemical equilibrium values due to strong upward ion velocities. Heat is deposited in a narrow region around the ionospheric peak, resulting in temperature profiles increasing sharply and reaching nearly constant values of 800-1000 deg K for electrons and 300 deg K for ions in the topside, assuming conditions appropriate for the wake region. In the subram region magnetic correction factors make the electron heat conductivities negligible, resulting in electron temperatures increasing strongly with altitude and reaching values in the order of 5000 deg K at our upper boundary located at 2200 km. Ion chemical heating is found to play an important role in shaping the ion energy balance in Titan's ionosphere.

  17. The energetics of Titan's ionosphere

    NASA Technical Reports Server (NTRS)

    Roboz, A.; Nagy, A. F.

    1994-01-01

    We have developed a comprehensive model to study the dynamics and energetics of the ionosphere of Titan. We solved the one-dimensional, time-dependent, coupled continuity and momentum equations for several ion species, together with single ion and electron energy equations, in order to calculate density, velocity, and temperature profiles. Calculations were carried out for several cases corresponding to different local times and configurations of the Titan-Saturn system. In our model the effects of horizontal magnetic fields were assumed to be negligible, except for their effect on reducing the electron and ion thermal conductivities and inhibiting vertical transport in the subram region. The ionospheric density peak was found to be at an altitude of about 1100 km, in accordance with earlier model calculations. The ionosphere is chemically controlled below an altitude of about 1500 km. Above this level, ion densities differ significantly from their chemical equilibrium values due to strong upward ion velocities. Heat is deposited in a narrow region around the ionospheric peak, resulting in temperature profiles increasing sharply and reaching nearly constant values of 800-1000 deg K for electrons and 300 deg K for ions in the topside, assuming conditions appropriate for the wake region. In the subram region magnetic correction factors make the electron heat conductivities negligible, resulting in electron temperatures increasing strongly with altitude and reaching values in the order of 5000 deg K at our upper boundary located at 2200 km. Ion chemical heating is found to play an important role in shaping the ion energy balance in Titan's ionosphere.

  18. Microwave Limb Sounder/El Nino Watch - December, 1997

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This image shows differences in atmospheric water vapor relative to a normal (average) year in the Earth's upper troposphere about 10 kilometers (6 miles) above the surface. The measurements were taken by the Microwave Limb Sounder (MLS) instrument aboard NASA's Upper Atmosphere Research Satellite (UARS). These data, collected in late December 1997, show higher than normal levels of water vapor (red) over the central and eastern Pacific which indicates the presence of an El Nino condition. At the same time, the western Pacific (blue) is much drier than normal. The unusually moist air above the central and eastern Pacific is a consequence of the much warmer-than-normal ocean waters which occur during El Nino. Warmer water evaporates at a higher rate and the resulting warm moist air rises and forms tall cloud towers. In the tropics, the warm water and the resulting tall cloud towers typically produce large amounts of rain. These data show significant increases in the amount of atmospheric moisture off the coast of Peru and Ecuador since measurements were made in November 1997. The maximum water temperature in the eastern tropical Pacific, as measured by the National Oceanic and Atmospheric Administration (NOAA), is still higher than normal and these high ocean temperatures are likely responsible for an increase in evaporation and the subsequent rise in humidity.

  19. The WHISPER Relaxation Sounder and the CLUSTER Active Archive

    NASA Astrophysics Data System (ADS)

    Trotignon, J. G.; Décréau, P. M. E.; Rauch, J. L.; Vallières, X.; Rochel, A.; Kougblénou, S.; Lointier, G.; Facskó, G.; Canu, P.; Darrouzet, F.; Masson, A.

    The Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation (WHISPER) instrument is part of the Wave Experiment Consortium (WEC) of the CLUSTER mission. With the help of the long double sphere antennae of the Electric Field and Wave (EFW) instrument and the Digital Wave Processor (DWP), it delivers active (sounding) and natural (transmitter off) electric field spectra, respectively from 4 to 82 kHz, and from 2 to 80 kHz. These frequency ranges have been chosen to include the electron plasma frequency, which is closely related to the total electron density, in most of the regions encountered by the CLUSTER spacecraft. Presented here is an overview of the WHISPER data products available in the CLUSTER Active Archive (CAA). The instrument and its performance are first recalled. The way the WHISPER products are obtained is then described, with particular attention being paid to the density determination. Both sounding and natural measurements are commonly used in this process, which depends on the ambient plasma regime. This is illustrated using drawings similar to the Bryant plots commonly used in the CLUSTER master science plan. These give a clear overview of typical density values and the parts of the orbits where they are obtained. More information on the applied software or on the quality/reliability of the density determination can also be highlighted.

  20. Scanning Mechanism of the FY-3 Microwave Humidity Sounder

    NASA Technical Reports Server (NTRS)

    Schmid, Manfred; Jing, Li; Hehr, Christian

    2010-01-01

    Astrium GmbH Germany, developed the scanning equipment for the instrument package of the MicroWave Humidity Sounder (MWHS) flying on the FY-3 meteorological satellite (FY means Feng Yun, Wind and Cloud) in a sun-synchronized orbit of 850-km altitude and at an inclination of 98.8 . The scanning mechanism rotates at variable velocity comprising several acceleration / deceleration phases during each revolution. The Scanning Mechanism contains two output shafts, each rotating a parabolic offset Antenna Reflector. The mechanism is operated in closed loop by means of redundant control electronics. MWHS is a sounding radiometer for measurement of global atmospheric water vapour profiles. An Engineering Qualification Model was developed and qualified and a first Flight Model was launched early 2008. The system is now working for more than two years successful in orbit. A second Flight Model of the Antenna Scanning Mechanism and of its associated control electronics was built and delivered to the customer for application on the follow-on spacecraft that will be launched by the end of 2010.

  1. The TIROS-N high resolution infrared radiation sounder

    NASA Technical Reports Server (NTRS)

    Koenig, E. W.

    1979-01-01

    The high-resolution infrared radiation sounder (HIRS/2) was developed and flown on the Television and Infrared Observation Satellite, N Series (TIROS-N) as one means of obtaining atmospheric vertical profile information. The HIRS/2 receives visible and infrared spectrum radiation through a single telescope and selects 20 narrow spectral channels by means of a rotating filter wheel. A passive radiant cooler provides an operating temperature of 106.7K for the HgCdTe and InSb detectors while the visible detector operates at instrument frame temperature. Low noise amplifiers and digital processing provide 13 bit data for spacecraft data multiplexing and transmission. The qualities of system performance that determine sounding capability are the dynamic range of data collection, the noise equivalent radiance of the system, the registration of the air columns sampled in each channel, and the ability to upgrade the calibration of the instrument to maintain the performance standard throughout life. The basic performance of the instrument in test is described. Early orbital information from the TIROS-N launched on October 13, 1978 are given and some observations on system quality are made.

  2. The Mars Climate Sounder In-Flight Positioning Anomaly

    NASA Technical Reports Server (NTRS)

    Jau, Bruno M.; Kass, David

    2008-01-01

    The paper discusses the Mars Climate Sounder (MCS) instrument s in-flight positioning errors and presents background material about it. A short overview of the instrument s science objectives and data acquisition techniques is provided. The brief mechanical description familiarizes the reader with the MCS instrument. Several key items of the flight qualification program, which had a rigorous joint drive test program but some limitations in overall system testing, are discussed. Implications this might have had for the flight anomaly, which began after several months of flawless space operation, are mentioned. The detection, interpretation, and instrument response to the errors is discussed. The anomaly prompted engineering reviews, renewed ground, and some in-flight testing. A summary of these events, including a timeline, is included. Several items of concern were uncovered during the anomaly investigation, the root cause, however, was never found. The instrument is now used with two operational constraints that work around the anomaly. It continues science gathering at an only slightly diminished pace that will yield approximately 90% of the originally intended science.

  3. Exploiting hyperspectral sounders for volcanic ash remote sensing

    NASA Astrophysics Data System (ADS)

    Western, Luke; Watson, Matthew; Francis, Peter

    2016-04-01

    Assumptions are made when retrieving properties of volcanic ash clouds using passive infrared satellite remote sensing. Assumptions in the retrieval method lead to larger uncertainties in the retrieved volcanic ash cloud properties. It is a general desire to reduce these uncertainties by removing some of the assumptions that must be made. Hyperspectral sounders provide the spectral capabilities to explore many of the physical parameters that describe volcanic ash clouds - the question is, which parameters is it possible to retrieve? We show that using the Infrared Atmospheric Sounding Interferometer (IASI) it is possible to retrieve the mass column loading and cloud top pressure of a volcanic ash cloud, together with the effective radius and spread of the ash particle size distribution, as well as the cloud top pressure of any underlying water cloud using an optimal estimation technique. We discuss the capabilities and shortcomings of the method. The consideration of an underlying water cloud is of importance for improving retrievals, and we place a particular focus on how well the particle size distribution can be described. More specifically, we investigate the viability of using either a lognormal or a gamma distribution to describe the distribution of ash particles, and we show that it is possible to retrieve information about the spread of a lognormal distribution of particles, whereas it is not for a gamma distribution. Some preliminary conclusions on the size distribution of volcanic ash are presented.

  4. Application of VISSR Atmospheric Sounder (VAS) data in weather analysis

    NASA Technical Reports Server (NTRS)

    Jedlovec, G. J.

    1984-01-01

    A technique which analyzes irregularly spaced satellite data is described. An experiment with rawinsonde and VISSR Atmospheric Sounder (VAS) radiance measurements collected on March 6-7, 1982 is conducted to reveal the applicability of the technique. The rawinsonde data are analyzed on a 16 x 12 grid using the two pass analysis scheme of Barnes (1973). A scheme similar to the Barnes (1973) procedure is employed to produce gridded analysis of VAS data over a 200 x 15000 km region in central part of the U.S. The use of a correction pass on the initial gridded field is described; the technique is extremely effective on uniformly spaced observations. The incorporation of the limited fine mesh model to the scheme to analyze data in sparse and cloudy regions is examined. A comparison of rawinsonde data with VAS data is provided. The technique proves effective for studying cloudy and sparse areas with VAS data and produces a four-dimensional data set with significant mesoscale structure.

  5. The Upper Atmosphere Research Satellite microwave limb sounder instrument

    NASA Technical Reports Server (NTRS)

    Barath, F. T.; Chavez, M. C.; Cofield, R. E.; Flower, D. A.; Frerking, M. A.; Gram, M. B.; Harris, W. M.; Holden, J. R.; Jarnot, R. F.; Kloezeman, W. G.

    1993-01-01

    The microwave limb sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) is the first satellite experiment using limb sounding techniques at microwave frequencies. Primary measurement objectives are stratospheric ClO, O3, H2O, temperature, and pressure. Measurements are of thermal emission: all are performed simultaneously and continuously and are not degraded by ice clouds or volcanic aerosols. The instrument has a 1.6-m mechanically scanning antenna system and contains heterodyne radiometers in spectral bands centred near 63, 183, and 205 GHz. The radiometers operate at ambient temperature and use Schottky-diode mixers with local oscillators derived from phase-locked Gunn oscillators. Frequency tripling by varactor multipliers generates the 183- and 205-GHz local oscillators, and quasi-optical techniques inject these into the mixers. Six 15-channel filter banks spectrally resolve stratospheric thermal emission lines and produce an output spectrum every 2 s. Thermal stability is sufficient for 'total power' measurements which do not require fast chopping. Radiometric calibration, consisting of measurements of cold space and an internal target, is performed every 65-s limb scan. Instrument in-orbit performance has been excellent, and all objectives are being met.

  6. Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST) Instrument Handbook

    SciTech Connect

    Flynn, Connor J.

    2016-03-01

    The Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST) measures the absolute infrared (IR) spectral radiance (watts per square meter per steradian per wavenumber) of the sky directly above the instrument. More information about the instrument can be found through the manufacturer’s website. The spectral measurement range of the instrument is 3300 to 520 wavenumbers (cm-1) or 3-19.2 microns for the normal-range instruments and 3300 to 400 cm-1 or 3-25 microns, for the extended-range polar instruments. Spectral resolution is 1.0 cm-1. Instrument field-of-view is 1.3 degrees. Calibrated sky radiance spectra are produced on cycle of about 141 seconds with a group of 6 radiance spectra zenith having dwell times of about 14 seconds each interspersed with 55 seconds of calibration and mirror motion. The ASSIST data is comparable to the Atmospheric Emitted Radiance Interferometer (AERI) data and can be used for 1) evaluating line-by-line radiative transport codes, 2) detecting/quantifying cloud effects on ground-based measurements of infrared spectral radiance (and hence is valuable for cloud property retrievals), and 3) calculating vertical atmospheric profiles of temperature and water vapor and the detection of trace gases.

  7. Wavelet-based coding of ultraspectral sounder data

    NASA Astrophysics Data System (ADS)

    Garcia-Vilchez, Fernando; Serra-Sagrista, Joan; Auli-Llinas, Francesc

    2005-08-01

    In this paper we provide a study concerning the suitability of well-known image coding techniques originally devised for lossy compression of still natural images when applied to lossless compression of ultraspectral sounder data. We present here the experimental results of six wavelet-based widespread coding techniques, namely EZW, IC, SPIHT, JPEG2000, SPECK and CCSDS-IDC. Since the considered techniques are 2-dimensional (2D) in nature but the ultraspectral data are 3D, a pre-processing stage is applied to convert the two spatial dimensions into a single spatial dimension. All the wavelet-based techniques are competitive when compared either to the benchmark prediction-based methods for lossless compression, CALIC and JPEG-LS, or to two common compression utilities, GZIP and BZIP2. EZW, SPIHT, SPECK and CCSDS-IDC provide a very similar performance, while IC and JPEG2000 improve the compression factor when compared to the other wavelet-based methods. Nevertheless, they are not competitive when compared to a fast precomputed vector quantizer. The benefits of applying a pre-processing stage, the Bias Adjusted Reordering, prior to the coding process in order to further exploit the spectral and/or spatial correlation when 2D techniques are employed, are also presented.

  8. Sensitivity Analysis for Atmospheric Infrared Sounder (AIRS) CO2 Retrieval

    NASA Technical Reports Server (NTRS)

    Gat, Ilana

    2012-01-01

    The Atmospheric Infrared Sounder (AIRS) is a thermal infrared sensor able to retrieve the daily atmospheric state globally for clear as well as partially cloudy field-of-views. The AIRS spectrometer has 2378 channels sensing from 15.4 micrometers to 3.7 micrometers, of which a small subset in the 15 micrometers region has been selected, to date, for CO2 retrieval. To improve upon the current retrieval method, we extended the retrieval calculations to include a prior estimate component and developed a channel ranking system to optimize the channels and number of channels used. The channel ranking system uses a mathematical formalism to rapidly process and assess the retrieval potential of large numbers of channels. Implementing this system, we identifed a larger optimized subset of AIRS channels that can decrease retrieval errors and minimize the overall sensitivity to other iridescent contributors, such as water vapor, ozone, and atmospheric temperature. This methodology selects channels globally by accounting for the latitudinal, longitudinal, and seasonal dependencies of the subset. The new methodology increases accuracy in AIRS CO2 as well as other retrievals and enables the extension of retrieved CO2 vertical profiles to altitudes ranging from the lower troposphere to upper stratosphere. The extended retrieval method for CO2 vertical profile estimation using a maximum-likelihood estimation method. We use model data to demonstrate the beneficial impact of the extended retrieval method using the new channel ranking system on CO2 retrieval.

  9. Validation of UARS Microwave Limb Sounder ClO Measurements

    NASA Technical Reports Server (NTRS)

    Waters, J. W.; Read, W. G.; Froidevaux, L.; Lungu, T. A.; Perun, V. S.; Stachnik, R. A.; Jarnot, R. F.; Cofield, R. E.; Fishbein, E. F.; Flower, D. A.; Burke, J. R.; Hardy, J. C.; Nakamura, L. L.; Ridenoure, B. P.; Shippony, Z.; Thurstans, R. P.; Thurstans, R. P.; Avallone, L. M.; Toohey, D. W.; deZafra, R. L.; Shindell, D. T.

    1996-01-01

    Validation of stratospheric ClO measurements by the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) is described. Credibility of the measurements is established by (1) the consistency of the measured ClO spectral emission line with the retrieved ClO profiles and (2) comparisons of ClO from MLS with that from correlative measurements by balloon-based, ground-based, and aircraft-based instruments. Values of "noise" (random), "scaling" (multiplicative), and "bias" (additive) uncertainties are determined for the Version 3 data, in the first version public release of the known artifacts in these data are identified. Comparisons with correlative measurements indicate agreement to within the combined uncertainties expected for MLS and the other measurements being compared. It is concluded that MLS Version 3 ClO data, with proper consideration of the uncertainties and "quality" parameters produced with these data, can be used for scientific analyses at retrieval surfaces between 46 and 1 hPa (approximately 20-50 km in height). Future work is planned to correct known problems in the data and improve their quality.

  10. The Impact of Atmospheric InfraRed Sounder (AIRS) Profiles on Short-term Weather Forecasts

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung; Zavodsky, Brad; Jedlovec, Gary J.; Lapenta, William

    2007-01-01

    The Atmospheric Infrared Sounder (AIRS), together with the Advanced Microwave Sounding Unit (AMSU), represents one of the most advanced spacebased atmospheric sounding systems. The combined AlRS/AMSU system provides radiance measurements used to retrieve temperature profiles with an accuracy of 1 K over 1 km layers under both clear and partly cloudy conditions, while the accuracy of the derived humidity profiles is 15% in 2 km layers. Critical to the successful use of AIRS profiles for weather and climate studies is the use of profile quality indicators and error estimates provided with each profile Aside form monitoring changes in Earth's climate, one of the objectives of AIRS is to provide sounding information of sufficient accuracy such that the assimilation of the new observations, especially in data sparse region, will lead to an improvement in weather forecasts. The purpose of this paper is to describe a procedure to optimally assimilate highresolution AIRS profile data in a regional analysis/forecast model. The paper will focus on the impact of AIRS profiles on a rapidly developing east coast storm and will also discuss preliminary results for a 30-day forecast period, simulating a quasi-operation environment. Temperature and moisture profiles were obtained from the prototype version 5.0 EOS science team retrieval algorithm which includes explicit error information for each profile. The error profile information was used to select the highest quality temperature and moisture data for every profile location and pressure level for assimilation into the ARPS Data Analysis System (ADAS). The AIRS-enhanced analyses were used as initial fields for the Weather Research and Forecast (WRF) system used by the SPORT project for regional weather forecast studies. The ADASWRF system will be run on CONUS domain with an emphasis on the east coast. The preliminary assessment of the impact of the AIRS profiles will focus on quality control issues associated with AIRS

  11. Impact of Atmospheric Infrared Sounder (AIRS) Thermodynamic Profiles on Regional Weather Forecasting

    NASA Technical Reports Server (NTRS)

    Chou, Shih-Hung; Zavodsky, Bradley T.; Jedlovee, Gary J.

    2010-01-01

    In data sparse regions, remotely-sensed observations can be used to improve analyses and lead to better forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), provides temperature and moisture profiles with accuracy comparable to that of radiosondes. The purpose of this paper is to describe a procedure to assimilate AIRS thermodynamic profile data into a regional configuration of the Advanced Research Weather Research and Forecasting (WRF-ARW) model using its three-dimension variational (3DVAR) analysis component (WRF-Var). Quality indicators are used to select only the highest quality temperature and moisture profiles for assimilation in both clear and partly cloudy regions. Separate error characteristics for land and water profiles are also used in the assimilation process. Assimilation results indicate that AIRS profiles produce an analysis closer to in situ observations than the background field. Forecasts from a 37-day case study period in the winter of 2007 show that AIRS profile data can lead to improvements in 6-h cumulative precipitation forecasts due to instability added in the forecast soundings by the AIRS profiles. Additionally, in a convective heavy rainfall event from February 2007, assimilation of AIRS profiles produces a more unstable boundary layer resulting in enhanced updrafts in the model. These updrafts produce a squall line and precipitation totals that more closely reflect ground-based observations than a no AIRS control forecast. The location of available high-quality AIRS profiles ahead of approaching storm systems is found to be of paramount importance to the amount of impact the observations will have on the resulting forecasts.

  12. Impact of Atmospheric Infrared Sounder (AIRS) Thermodynamic Profiles on Regional Precipitation Forecasting

    NASA Technical Reports Server (NTRS)

    Chou, S.-H.; Zavodsky, B. T.; Jedloved, G. J.

    2010-01-01

    In data sparse regions, remotely-sensed observations can be used to improve analyses and lead to better forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), provides temperature and moisture profiles in clear and cloudy regions with accuracy which approaches that of radiosondes. The purpose of this paper is to describe an approach to assimilate AIRS thermodynamic profile data into a regional configuration of the Advanced Research WRF (ARW) model using WRF-Var. Quality indicators are used to select only the highest quality temperature and moisture profiles for assimilation in clear and partly cloudy regions, and uncontaminated portions of retrievals above clouds in overcast regions. Separate error characteristics for land and water profiles are also used in the assimilation process. Assimilation results indicate that AIRS profiles produce an analysis closer to in situ observations than the background field. Forecasts from a 37-day case study period in the winter of 2007 show that AIRS profile data can lead to improvements in 6-h cumulative precipitation forecasts resulting from improved thermodynamic fields. Additionally, in a convective heavy rainfall event from February 2007, assimilation of AIRS profiles produces a more unstable boundary layer resulting in enhanced updrafts in the model. These updrafts produce a squall line and precipitation totals that more closely reflect ground-based observations than a no AIRS control forecast. The location of available high-quality AIRS profiles ahead of approaching storm systems is found to be of paramount importance to the amount of impact the observations will have on the resulting forecasts.

  13. The dynamics of the Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Miller, K. L.

    1988-01-01

    Data from the Pioneer-Venus orbiter has demonstrated the importance of understanding ion dynamics in the Venus ionosphere. The analysis of the data has shown that during solar maximum the topside Venus ionosphere in the dark hemisphere is generated almost entirely on the dayside of the planet during solar maximum, and flows with supersonic velocities across the terminator into the nightside. The flow field in the ionosphere is mainly axially-symmetric about the sun-Venus axis, as are most measured ionospheric quantities. The primary data base used consisted of the ion velocity measurements made by the RPA during three years that periapsis of the orbiter was maintained in the Venus ionosphere. Examples of ion velocities were published and modeled. This research examined the planetary flow patterns measured in the Venus ionosphere, and the physical implications of departures from the mean flow.

  14. Interaction of Titan's ionosphere with Saturn's magnetosphere.

    PubMed

    Coates, Andrew J

    2009-02-28

    Titan is the only Moon in the Solar System with a significant permanent atmosphere. Within this nitrogen-methane atmosphere, an ionosphere forms. Titan has no significant magnetic dipole moment, and is usually located inside Saturn's magnetosphere. Atmospheric particles are ionized both by sunlight and by particles from Saturn's magnetosphere, mainly electrons, which reach the top of the atmosphere. So far, the Cassini spacecraft has made over 45 close flybys of Titan, allowing measurements in the ionosphere and the surrounding magnetosphere under different conditions. Here we review how Titan's ionosphere and Saturn's magnetosphere interact, using measurements from Cassini low-energy particle detectors. In particular, we discuss ionization processes and ionospheric photoelectrons, including their effect on ion escape from the ionosphere. We also discuss one of the unexpected discoveries in Titan's ionosphere, the existence of extremely heavy negative ions up to 10000amu at 950km altitude.

  15. Analysis of direction-of-arrival aliasing for MF/HF Doppler-sorted interferometry measurements of ionospheric drift

    NASA Astrophysics Data System (ADS)

    Parkinson, M. L.; Dyson, P. L.; Smith, P. R.

    1997-05-01

    The determination of accurate direction of arrival (DOA) of echoes is paramount when performing Doppler-sorted interferometry (DSI) at MF/HF to measure the drift of ionospheric plasma. Important factors affecting the accuracy include inadequate signal-to-noise ratio (SNR) and coherency of ionospheric echoes. As the SNR deteriorates, there is an increase in the errors in the phases measured at the individual antennas of an array, and this leads to ambiguities in DOA equivalent to directional aliasing. In this paper we model this effect, the effects of Doppler-frequency aliasing, and the finite resolution of Doppler spectra. We thereby show the importance for vertical incident sounders of rejecting echoes with large off-vertical angles, and the choice of appropriate signal-processing parameters for the accurate estimation of ionospheric motions. As an example, we consider the situation for vertical incident ionosondes and show that a low SNR can produce spurious echoes at relatively large zenith angles, which can, however, be avoided or minimized by the suitable choice of operating parameters.

  16. Evidence and effects of the sunrise enhancement of the equatorial vertical plasma drift in the F region ionosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding

    2016-05-01

    Recent studies based on the satellite observations demonstrated that the equatorial vertical plasma drift can also enhance near sunrise in a way similar to the prereversal enhancement. However, it is not clear whether the signature of this sunrise enhancement appears in observations with other sounding techniques. In this work, we explore the Jicamarca (12°S, 283.2°E) incoherent scatter radar measurements to present the evidence of sunrise enhancement in vertical plasma drift on 12 May and 10 June 2004, which are under magnetically quiet and solar minimum conditions. The effects of the sunrise enhancement on the ionosphere are, for the first time, investigated by analyzing the ionograms recorded by the Digisonde Portable Sounder at Jicamarca and conducting the Theoretical Ionospheric Model of the Earth in Institute of Geology and Geophysics, Chinese Academy of Sciences. The observations showed that, during the sunrise enhancement, the F2 layer peak height is lifted remarkably, and the F2 layer peak density and bottomside electron density tend to decrease compared to the days without sunrise enhancements. The simulations indicated that the sunrise enhancement drift can lift the equatorial ionosphere to higher heights and distort the equatorial electron density profiles. What is more, the simulations display an F3 layer in the equatorial F region during the sunrise enhancement, and a new F2 layer develops at lower altitudes under the jointed control of the usual photochemical and dynamical processes.

  17. Studies based on global subsurface radar sounding of the Moon by SELENE (Kaguya) Lunar Radar Sounder (LRS): A summary

    NASA Astrophysics Data System (ADS)

    Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Kobayashi, T.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Goto, Y.

    2015-12-01

    The Lunar Radar Sounder (LRS) onboard the SELENE (Kaguya) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 130 million pulses worth of radar sounder data have been obtained [Ono et al., 2010]. Based on the datasets of the first lunar global subsurface radar sounding, Ono et al. [2009] revealed that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Based on the further survey, Pommerol et al. [2010] pointed out the negative correlation of clear subsurface echoes with the maps of ilmenite, and suggested that dense ilmenite attenuates the radar pulse in the basaltic mare lava, and cause the absence of the clear subsurface echoes. That also suggests there are undetected subsurface reflectors especially below the young lava flow units with high ilmenite abundance. Kobayashi et al. [2012] applied synthetic aperture radar (SAR) processing to SELENE LRS data in order to obtain distinct radargram. Taking advantage of analyzing waveform data sent via high data rate telemetry from the Moon, we can perform advanced data analyses on the ground. We started providing the both SAR processed and waveform datasets via SELENE Data Archive (http://l2db.selene.darts.isas.jaxa.jp/index.html.en) since 2015. Oshigami et al. [2014] estimated volumes of basalt units in the ages of 2.7 Ga to 3.8 Ga in the nearside maria. The volume was derived from the depth of subsurface reflectors measured by LRS. The volumes of the geologic units were 103 to 104 km3. The average eruption rates were 10-5 to 10-3 km3 yr-1. The estimated volumes

  18. Ionospheric Change and Solar EUV Irradiance

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    The ionosphere has been quantitatively monitored for the past six solar cycles. The past few years of observations are showing trends that differ from the prior cycles! Our good statistical relationships between the solar radio flux index at 10.7 cm, the solar EUV Irradiance, and the ionospheric F-layer peak density are showing indications of divergence! Present day discussion of the Sun-Earth entering a Dalton Minimum would suggest change is occurring in the Sun, as the driver, followed by the Earth, as the receptor. The dayside ionosphere is driven by the solar EUV Irradiance. But different components of this spectrum affect the ionospheric layers differently. For a first time the continuous high cadence EUV spectra from the SDO EVE instrument enable ionospheric scientists the opportunity to evaluate solar EUV variability as a driver of ionospheric variability. A definitive understanding of which spectral components are responsible for the E- and F-layers of the ionosphere will enable assessments of how over 50 years of ionospheric observations, the solar EUV Irradiance has changed. If indeed the evidence suggesting the Sun-Earth system is entering a Dalton Minimum periods is correct, then the comprehensive EVE solar EUV Irradiance data base combined with the ongoing ionospheric data bases will provide a most fortuitous fiduciary reference baseline for Sun-Earth dependencies. Using the EVE EUV Irradiances, a physics based ionospheric model (TDIM), and 50 plus years of ionospheric observation from Wallops Island (Virginia) the above Sun-Earth ionospheric relationship will be reported on.

  19. Periodic Structures in the Equatorial Ionosphere (Postprint)

    DTIC Science & Technology

    2012-05-13

    AFRL-RV-PS- AFRL-RV-PS- TP-2012-0004 TP-2012-0004 PERIODIC STRUCTURES IN THE EQUATORIAL IONOSPHERE (POSTPRINT) Cheryl Y. Huang...in the Equatorial Ionosphere (Postprint) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) 5d. PROJECT NUMBER 2301...International Reference Ionosphere model to remove variations in density due to changes in spacecraft altitude and latitude along the orbit. In this

  20. New method for deriving the topside ionospheric Vary-Chap scale height

    NASA Astrophysics Data System (ADS)

    Wang, Sicheng; Huang, Sixun; Fang, Hanxian

    2015-09-01

    An α-Chapman function with a continuously varying scale height H(h) can be used to describe the topside ionosphere electron density profile that seamlessly connects the ionosphere with the plasmasphere. Huang and Reinisch have derived the analytic expression of the scale height from the Vary-Chap function, which can be applied to the topside F2 region. However, the H(h) is still difficult to obtain because H(h) is a function of the unknown value H(h) at hmF2. In this paper, the maximum entropy method is introduced to solve this ill-posed problem, and the Vary-Chap scale height for each electron density profile is derived. Then the average percentage errors that defined as the differences between the measured electron density profiles and the Vary-Chap profiles obtained from the Vary-Chap scale heights are calculated with the Alouette/ISIS satellites topside sounder database. The results reveal that the average percentage errors are generally less than 5% and the Vary-Chap profiles can well represent the topside electron density profiles. What is more, the local time, seasonal, solar cycle, and latitudinal variations of the Vary-Chap scale height are preliminarily analyzed.

  1. HAARP-Induced Ionospheric Ducts

    SciTech Connect

    Milikh, Gennady; Vartanyan, Aram

    2011-01-04

    It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents observations of the plasma density perturbations caused by the HF-heating of the ionosphere by the HAARP facility. The low orbit satellite DEMETER was used as a diagnostic tool to measure the electron and ion temperature and density along the satellite orbit overflying close to the magnetic zenith of the HF-heater. Those observations will be then checked against the theoretical model of duct formation due to HF-heating of the ionosphere. The model is based on the modified SAMI2 code, and is validated by comparison with well documented experiments.

  2. Investigation of traveling ionospheric disturbances

    NASA Technical Reports Server (NTRS)

    Grossi, M.; Estes, R. D.

    1981-01-01

    Maximum entropy power spectra of the ionospheric electron density were constructed to enable PINY to compare them with the power independently obtained by PINY with in situ measurements of ionospheric electron density and neutral species performed with instrumentation carried by the Atmospheric Explorer (AE) satellite. This comparison corroborated evidence on the geophysical reality of the alleged electron density irregularities detected by the ASTP dual frequency Doppler link. Roughly half of the localized wave structures which are confined to dimensions of 1800 km or less (as seen by an orbiting Doppler baseline) were found to be associated with the larger crest of the geomagnetic anomaly in the Southern (winter) Hemisphere in the morning. The observed nighttime structures are also associated with local peaks in the electron density.

  3. Ionospheric limitations to time transfer by satellite

    NASA Technical Reports Server (NTRS)

    Knowles, S. H.

    1983-01-01

    The ionosphere can contribute appreciable group delay and phase change to radio signals traversing it; this can constitute a fundamental limitation to the accuracy of time and frequency measurements using satellites. Because of the dispersive nature of the ionosphere, the amount of delay is strongly frequency-dependent. Ionospheric compensation is necessary for the most precise time transfer and frequency measurements, with a group delay accuracy better than 10 nanoseconds. A priori modeling is not accurate to better than 25%. The dual-frequency compensation method holds promise, but has not been rigorously experimentally tested. Irregularities in the ionosphere must be included in the compensation process.

  4. Ionospheric research for space weather service support

    NASA Astrophysics Data System (ADS)

    Stanislawska, Iwona; Gulyaeva, Tamara; Dziak-Jankowska, Beata

    2016-07-01

    Knowledge of the behavior of the ionosphere is very important for space weather services. A wide variety of ground based and satellite existing and future systems (communications, radar, surveillance, intelligence gathering, satellite operation, etc) is affected by the ionosphere. There are the needs for reliable and efficient support for such systems against natural hazard and minimalization of the risk failure. The joint research Project on the 'Ionospheric Weather' of IZMIRAN and SRC PAS is aimed to provide on-line the ionospheric parameters characterizing the space weather in the ionosphere. It is devoted to science, techniques and to more application oriented areas of ionospheric investigation in order to support space weather services. The studies based on data mining philosophy increasing the knowledge of ionospheric physical properties, modelling capabilities and gain applications of various procedures in ionospheric monitoring and forecasting were concerned. In the framework of the joint Project the novel techniques for data analysis, the original system of the ionospheric disturbance indices and their implementation for the ionosphere and the ionospheric radio wave propagation are developed since 1997. Data of ionosonde measurements and results of their forecasting for the ionospheric observatories network, the regional maps and global ionospheric maps of total electron content from the navigational satellite system (GNSS) observations, the global maps of the F2 layer peak parameters (foF2, hmF2) and W-index of the ionospheric variability are provided at the web pages of SRC PAS and IZMIRAN. The data processing systems include analysis and forecast of geomagnetic indices ap and kp and new eta index applied for the ionosphere forecasting. For the first time in the world the new products of the W-index maps analysis are provided in Catalogues of the ionospheric storms and sub-storms and their association with the global geomagnetic Dst storms is

  5. Laser Atmospheric Wind Sounder (LAWS) phase 1. Volume 2

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This report summarizes and documents the results of the 12-month phase 1 work effort. The objective of phase 1 was to establish the conceptional definition of the laser atmospheric wind sounder (LAWS) sensor system, including accommodations analyses to ensure compatibility with the Space Station Freedom (SSF) and the Earth Observing System (EOS) Polar Orbiting Platform (POP). Various concepts were investigated with trade studies performed to select the configuration to be carried forward to the phase 2 Preliminary Design Definition. A summary of the LAWS system and subsystem trade studies that were performed leading to the baseline design configuration is presented in the appendix. The overall objective of the LAWS Project is to define, design, and implement an operational space based facility, LAWS, for accurate measurement of Earth wind profiles. Phase 1 addressed three major areas: (1) requirements definition; (2) instrument concepts and configurations; and (3) performance analysis. For the LAWS instrument concepts and configurations, the issues which press the technological state of the art are reliable detector lifetime and laser performance and lifetime. Lag angle compensation, pointing accuracy, satellite navigation, and telescope design are significant technical issues, but they are considered to be currently state of the art. The primary issues for performance analysis concern interaction with the atmosphere in terms of backscatter and attenuation, wind variance, and cloud blockage. The phase 1 tasks were formulated to address these significant technical issues and demonstrate the technical feasibility of the LAWS concept. Primary emphasis was placed on analysis/trade and identification of candidate concepts. Promising configurations were evaluated for performance, sensitivities, risks, and budgetary costs. Lockheed's baseline LAWS configuration is presented.

  6. Validation of Aura Microwave Limb Sounder HCl Measurements

    NASA Technical Reports Server (NTRS)

    Froidevaux, L.; Jiang, Y. B.; Lambert, A.; Livesey, N. J.; Read, W. G.; Waters, J. W.; Fuller, R. A.; Marcy, T. P.; Popp, P. J.; Gao, R. S.; Fahey, D. W.; Jucks, K. W.; Stachnik, R. A.; Toon, G. C.; Christensen, L. E.; Webster, C. R.; Bernath, P. F.; Boone, C. D.; Walker, K. A.; Pumphrey, H. C.; Harwood, R. S.; Manney, G. L.; Schwartz, M. J.; Daffer, W. H.; Drouin, B. J.

    2008-01-01

    The Earth Observing System (EOS) Microwave Limb Sounder (MLS) aboard the Aura satellite has provided daily global HCl profiles since August 2004. We provide a characterization of the resolution, random and systematic uncertainties, and known issues for the version 2.2 MLS HCl data. The MLS sampling allows for comparisons with many (1500 to more than 3000) closely matched profiles from the Halogen Occultation Experiment (HALOE) and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). These data sets provide HCl latitudinal distributions that are, overall, very similar to those from (coincident) MLS profiles, although there are some discrepancies in the upper stratosphere between the MLS and HALOE gradients. As found in previous work, MLS and ACE HCl profiles agree very well (within approximately 5%, on average), but the MLS HCl abundances are generally larger (by 10-20%) than HALOE HCl. The bias versus HALOE is unlikely to arise mostly from MLS, as a similar systematic bias (of order 15%) is not observed between average MLS and balloon-borne measurements of HCl, obtained over Fort Sumner, New Mexico, in 2004 and 2005. At the largest pressure (147 hPa) for MLS HCl, a high bias (approximately 0.2 ppbv) is apparent in analyses of low to midlatitude data versus in situ aircraft chemical ionization mass spectrometry (CIMS) HCl measurements from the Aura Validation Experiment (AVE) campaigns in 2004, 2005, and 2006; this bias is also observed in comparisons of MLS and aircraftHCl/O3 correlations. Good agreement between MLS and CIMS HCl is obtained at 100 to 68 hPa. The recommended pressure range for MLS HCl is from 100 to 0.15 hPa.

  7. Validation of UARS Microwave Limb Sounder Temperature and Pressure Measurements

    NASA Technical Reports Server (NTRS)

    Fishbein, E. F.; Cofield, R. E.; Froidevaux, L.; Jarnot, R. F.; Lungu, T.; Read, W. G.; Shippony, Z.; Waters, J. W.; McDermid, I. S.; McGee, T. J.; Singh, U.; Gross, M.; Hauchecorne, A.; Keckhut, P.; Gelman, M. E.; Nagatani, R. M.

    1996-01-01

    The accuracy and precision of the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) atmospheric temperature and tangent-point pressure measurements are described. Temperatures and tangent- point pressure (atmospheric pressure at the tangent height of the field of view boresight) are retrieved from a 15-channel 63-GHz radiometer measuring O2 microwave emissions from the stratosphere and mesosphere. The Version 3 data (first public release) contains scientifically useful temperatures from 22 to 0.46 hPa. Accuracy estimates are based on instrument performance, spectroscopic uncertainty and retrieval numerics, and range from 2.1 K at 22 hPa to 4.8 K at 0.46 hPa for temperature and from 200 m (equivalent log pressure) at 10 hPa to 300 m at 0.1 hPa. Temperature accuracy is limited mainly by uncertainty in instrument characterization, and tangent-point pressure accuracy is limited mainly by the accuracy of spectroscopic parameters. Precisions are around 1 K and 100 m. Comparisons are presented among temperatures from MLS, the National Meteorological Center (NMC) stratospheric analysis and lidar stations at Table Mountain, California, Observatory of Haute Provence (OHP), France, and Goddard Spaceflight Center, Maryland. MLS temperatures tend to be 1-2 K lower than NMC and lidar, but MLS is often 5 - 10 K lower than NMC in the winter at high latitudes, especially within the northern hemisphere vortex. Winter MLS and OHP (44 deg N) lidar temperatures generally agree and tend to be lower than NMC. Problems with Version 3 MLS temperatures and tangent-point pressures are identified, but the high precision of MLS radiances will allow improvements with better algorithms planned for the future.

  8. Mare volcanism: Reinterpretation based on Kaguya Lunar Radar Sounder data

    NASA Astrophysics Data System (ADS)

    Oshigami, Shoko; Watanabe, Shiho; Yamaguchi, Yasushi; Yamaji, Atsushi; Kobayashi, Takao; Kumamoto, Atsushi; Ishiyama, Ken; Ono, Takayuki

    2014-05-01

    The Lunar Radar Sounder (LRS) onboard Kaguya (SELENE) detected widespread horizontal reflectors under some nearside maria. Previous studies estimated that the depths of the subsurface reflectors were up to several hundreds of meters and suggested that the reflectors were interfaces between mare basalt units. The comparison between the reflectors detected in the LRS data and surface age maps indicating the formation age of each basalt unit allows us to discuss the lower limit volume of each basalt unit and its space and time variation. We estimated volumes of basalt units in the ages of 2.7 Ga to 3.8 Ga in the nearside maria including Mare Crisium, Mare Humorum, Mare Imbrium, Mare Nectaris, Mare Serenitatis, Mare Smythii, and Oceanus Procellarum. The lower limit volumes of the geologic units estimated in this study were on the order of 103 to 104 km3. This volume range is consistent with the total amount of erupted lava flows derived from numerical simulations of thermal erosion models of lunar sinuous rille formation and is also comparable to the average flow volumes of continental flood basalt units formed after the Paleozoic and calculated flow volumes of Archean komatiite flows on the Earth. The lower limits of average eruption rates estimated from the unit volumes were on the order of 10-5 to 10-3 km3/yr. The estimated volumes of the geologic mare units and average eruption rate showed clear positive correlations with their ages within the same mare basin, while they vary among different maria compared within the same age range.

  9. Validation of UARS Microwave Limb Sounder Ozone Measurements

    NASA Technical Reports Server (NTRS)

    Froidevaux, L.; Read, W. G.; Lungu, T. A.; Cofield, R. E.; Fishbein, E. F.; Flower, D. A.; Jarnot, R. F.; Ridenoure, B. P.; Shippony, Z.; Waters, J. W.; Margitan, J. J.; McDermid, I. S.; Stachnik, R. A.; Peckham, G. E.; Braathen, G.; Deshler, T.; Fishman, J.; Hofmann, D. J.; Oltmans, S. J.

    1996-01-01

    This paper describes the validation of ozone data from the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS). The MLS ozone retrievals are obtained from the calibrated microwave radiances (emission spectra) in two separate bands, at frequencies near 205 and 183 GHz. Analyses described here focus on the MLS Version 3 data (the first set of files made publicly available). We describe results of simulations performed to assess the quality of the retrieval algorithms, in terms of both mixing ratio and radiance closure. From actual MLS observations, the 205-GHz ozone retrievals give better closure (smaller radiance residuals) than that from the 183-GHz measurements and should be considered more accurate from the calibration aspects. However, the 183-GHz data are less noise limited in the mesosphere and can provide the most useful scientific results in that region. We compare the retrieved 205-GHz ozone profiles in the middle-to lower stratosphere to ozonesonde measurements at a wide range of latitudes and seasons. Ground-based lidar data from Table Mountain, California, provide a good reference for comparisons at higher altitudes. Based on these analyses, comparisons with balloon-borne measurements and others, as well as a detailed budget of estimated uncertainties, MLS results appear to be generally of high quality, with some biases worth mentioning. Results for the lowermost stratosphere (approx. 50 to 100 bPa) are still in need of improvement. A set of estimated precision and accuracy values is derived for the MLS ozone data sets. We also comment on recent updates in the retrieval algorithms and their impact on ozone values.

  10. The UARS and EOS Microwave Limb Sounder (MLS) Experiments.

    NASA Astrophysics Data System (ADS)

    Waters, J. W.; Read, W. G.; Froidevaux, L.; Jarnot, R. F.; Cofield, R. E.; Flower, D. A.; Lau, G. K.; Pickett, H. M.; Santee, M. L.; Wu, D. L.; Boyles, M. A.; Burke, J. R.; Lay, R. R.; Loo, M. S.; Livesey, N. J.; Lungu, T. A.; Manney, G. L.; Nakamura, L. L.;  Perun, V. S.;  Ridenoure, B. P.;  Shippony, Z.;  Siegel, P. H.;  Thurstans, R. P.;  Harwood, R. S.;  Pumphrey, H. C.;  Filipiak, M. J.

    1999-01-01

    The Microwave Limb Sounder (MLS) experiments obtain measurements of atmospheric composition, temperature, and pressure by observations of millimeter- and submillimeter-wavelength thermal emission as the instrument field of view is scanned through the atmospheric limb. Features of the measurement technique include the ability to measure many atmospheric gases as well as temperature and pressure, to obtain measurements even in the presence of dense aerosol and cirrus, and to provide near-global coverage on a daily basis at all times of day and night from an orbiting platform. The composition measurements are relatively insensitive to uncertainties in atmospheric temperature. An accurate spectroscopic database is available, and the instrument calibration is also very accurate and stable. The first MLS experiment in space, launched on the (NASA) Upper Atmosphere Research Satellite (UARS) in September 1991, was designed primarily to measure stratospheric profiles of ClO, O3, H2O, and atmospheric pressure as a vertical reference. Global measurement of ClO, the predominant radical in chlorine destruction of ozone, was an especially important objective of UARS MLS. All objectives of UARS MLS have been accomplished and additional geophysical products beyond those for which the experiment was designed have been obtained, including measurement of upper-tropospheric water vapor, which is important for climate change studies. A follow-on MLS experiment is being developed for NASA's Earth Observing System (EOS) and is scheduled to be launched on the EOS CHEMISTRY platform in late 2002. EOS MLS is designed for many stratospheric measurements, including HOx radicals, which could not be measured by UARS because adequate technology was not available, and better and more extensive upper-tropospheric and lower-stratospheric measurements.

  11. Heat budget of ionospheric electrons

    NASA Technical Reports Server (NTRS)

    Prasad, S. S.; Schneck, L. J.

    1976-01-01

    Heat input calculations were detached from solar extreme UV data and monatomic oxygen densities were derived from simultaneously measured data sets (ion composition 146-191 km) in a study of the heat budget of ionosphere electrons. Earlier inferences that cooling predominates over heating are supported. A search for additional heat sources or a revision of the cooling rates is recommended, by way of balancing the heat budget. Importance is attached to electron cooling by fine structure excitation of monatomic oxygen.

  12. Ionospheric Research Using Digital Ionosondes.

    DTIC Science & Technology

    1983-07-01

    employed by your organization, please notify AFGL/DAA, Hanscom AFB, MA 01731. This will assist us in maintaining a current mailing list. Do not return...know, that outputs the standard ionospheric param- eters and profiles in real time, even under disturbed condi- tions. This breakthrough will make it...Echo signals arriving from directions other than the programmed beam direction will be wrongly identified in the ionograms, depending upon which antenna

  13. Ionospheric very low frequency transmitter

    SciTech Connect

    Kuo, Spencer P.

    2015-02-15

    The theme of this paper is to establish a reliable ionospheric very low frequency (VLF) transmitter, which is also broad band. Two approaches are studied that generate VLF waves in the ionosphere. The first, classic approach employs a ground-based HF heater to directly modulate the high latitude ionospheric, or auroral electrojet. In the classic approach, the intensity-modulated HF heater induces an alternating current in the electrojet, which serves as a virtual antenna to transmit VLF waves. The spatial and temporal variations of the electrojet impact the reliability of the classic approach. The second, beat-wave approach also employs a ground-based HF heater; however, in this approach, the heater operates in a continuous wave mode at two HF frequencies separated by the desired VLF frequency. Theories for both approaches are formulated, calculations performed with numerical model simulations, and the calculations are compared to experimental results. Theory for the classic approach shows that an HF heater wave, intensity-modulated at VLF, modulates the electron temperature dependent electrical conductivity of the ionospheric electrojet, which, in turn, induces an ac electrojet current. Thus, the electrojet becomes a virtual VLF antenna. The numerical results show that the radiation intensity of the modulated electrojet decreases with an increase in VLF radiation frequency. Theory for the beat wave approach shows that the VLF radiation intensity depends upon the HF heater intensity rather than the electrojet strength, and yet this approach can also modulate the electrojet when present. HF heater experiments were conducted for both the intensity modulated and beat wave approaches. VLF radiations were generated and the experimental results confirm the numerical simulations. Theory and experimental results both show that in the absence of the electrojet, VLF radiation from the F-region is generated via the beat wave approach. Additionally, the beat wave approach

  14. Saturn's ionosphere - Inferred electron densities

    NASA Astrophysics Data System (ADS)

    Kaiser, M. L.; Desch, M. D.; Connerney, J. E. P.

    1984-04-01

    During the two Voyager encounters with Saturn, radio bursts were detected which appear to have originated from atmospheric lightning storms. Although these bursts generally extended over frequencies from as low as 100 kHz to the upper detection limit of the instrument, 40 MHz, they often exhibited a sharp but variable low frequency cutoff below which bursts were not detected. We interpret the variable low-frequency extent of these bursts to be due to the reflection of the radio waves as they propagate through an ionosphere which varies with local time. We obtain estimates of electron densities at a variety of latitude and local time locations. These compare well with the dawn and dusk densities measured by the Pioneer 11 Voyager Radio Science investigations, and with model predictions for dayside densities. However, we infer a two-order-of-magnitude diurnal variation of electron density, which had not been anticipated by theoretical models of Saturn's ionosphere, and an equally dramatic extinction of ionospheric electron density by Saturn's rings. Previously announced in STAR as N84-17102

  15. Challenges in Solar System Ionospheres

    NASA Astrophysics Data System (ADS)

    Mendillo, M.

    2001-12-01

    The solar system contains a robust set of ionospheres among its nine planets, many moons and comets. If one sets aside the transient atmospheres/ionospheres of comets, and those of larger bodies with tenuous surface-boundary-exospheres (e.g., Mercury, Moon, Europa, etc.), plus the under-sampled Pluto, then 10 case studies exist for detailed study and comparison (Venus, Earth, Mars, Jupiter & Io, Saturn & Titan, Uranus, and Neptune & Triton). The ionospheres of these bodies define the full range of natural processes that govern plasma environments in our solar system, and indeed for extra-solar-system planets: (a) photo-chemical mechanisms, (b) energetic (auroral) ionization sources, (c) mesospheric/thermospheric tides, winds and waves, (d) electrodynamics, and (e) solar wind impact and/or shielding by a magnetosphere. This brief review will summarize and compare the dominant production, loss and transport mechanisms thought to occur at each site. Major uncertainties are, surprisingly, not due entirely to remoteness of the bodies being studied.

  16. Dynamic Ionosphere Cubesat Experiment (DICE)

    NASA Astrophysics Data System (ADS)

    Crowley, G.; Fish, C. S.; Bust, G. S.; Swenson, C.; Barjatya, A.; Larsen, M. F.

    2009-12-01

    The Dynamic Ionosphere Cubesat Experiment (DICE) mission has been selected for flight under the NSF "CubeSat-based Science Mission for Space Weather and Atmospheric Research" program. The mission has three scientific objectives: (1) Investigate the physical processes responsible for formation of the midlatitude ionospheric Storm Enhanced Density (SED) bulge in the noon to post-noon sector during magnetic storms; (2) Investigate the physical processes responsible for the formation of the SED plume at the base of the SED bulge and the transport of the high density SED plume across the magnetic pole; (3) Investigate the relationship between penetration electric fields and the formation and evolution of SED. The mission consists of two identical Cubesats launched simultaneously. Each satellite carries a fixed-bias DC Langmuir Probe (DCP) to measure in-situ ionospheric plasma densities, and an Electric Field Probe (EFP) to measure DC and AC electric fields. These measurements will permit accurate identification of storm-time features such as the SED bulge and plume, together with simultaneous co-located electric field measurements which have previously been missing. The mission team combines expertise from ASTRA, Utah State University/Space Dynamics Laboratory (USU/SDL), Embry-Riddle Aeronautical University and Clemson University.

  17. Mechanisms of Ionospheric Mass Ejection

    NASA Technical Reports Server (NTRS)

    Moore, Thomas Earle; Khazanov, George V.; Hannah, Mei-Ching; Glocer, Alex

    2010-01-01

    Ionospheric outflows are directly responsive to solar wind disturbances, particularly in the dayside auroral cusp or cleft regions. Inputs of both electromagnetic energy (Poynting flux) and kinetic energy (particle precipitation) are closely correlated with these outflows. We assess the importance of processes thought to drive ionospheric outflows. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitation particles. Solar wind energy dissipation is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma and neutral gas. We assess the importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multi-species global simulation codes. We conclude by assessing outstanding obstacles to this objective.

  18. Ionospheric Drivers of ISS Charging

    NASA Astrophysics Data System (ADS)

    Minow, J. I.; Willis, E. M.

    2015-12-01

    Severe spacecraft surface charging in terrestrial environments typically results from exposure to energetic electrons at some 10's of keV within auroral environments at high latitudes in low Earth orbit or hot thermal plasma in geostationary orbit. Predicting surface charging of a vehicle in these environments depends on our ability to specify and forecast auroral acceleration events and geomagnetic storms. Measurements of ISS frame charging to date, in contrast, are dominated by US 160V solar array interactions with the ionospheric plasma environment with little evidence for strong charging during geomagnetic storms. Predicting ISS charging, therefore, requires an ability to specify and forecast components of ionospheric variability of importance to high voltage solar array interactions with the plasma environment. This presentation provides examples of the ionospheric conditions responsible for typical and extreme ISS charging and discusses current capabilities to forecast these events. Specific examples are given for ISS frame charging observed when the vehicle passes through low latitude dawn density depletions, high latitude plasma troughs, and plasma depletions associated with equatorial spread-f conditions.

  19. Saturn's ionosphere: Inferred electron densities

    NASA Technical Reports Server (NTRS)

    Kaiser, M. L.; Desch, M. D.; Connerney, J. E. P.

    1983-01-01

    During the two Voyager encounters with Saturn, radio bursts were detected which appear to have originated from atmospheric lightning storms. Although these bursts generally extended over frequencies from as low as 100 kHz to the upper detection limit of the instrument, 40 MHz, they often exhibited a sharp but variable low frequency cutoff below which bursts were not detected. We interpret the variable low-frequency extent of these bursts to be due to the reflection of the radio waves as they propagate through an ionosphere which varies with local time. We obtain estimates of electron densities at a variety of latitude and local time locations. These compare well with the dawn and dusk densitis measured by the Pioneer 11 Voyager Radio Science investigations, and with model predictions for dayside densities. However, we infer a two-order-of-magnitude diurnal variation of electron density, which had not been anticipated by theoretical models of Saturn's ionosphere, and an equally dramatic extinction of ionospheric electron density by Saturn's rings.

  20. Mechanisms of Ionospheric Mass Escape

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Khazanov, G. V.

    2010-01-01

    The dependence of ionospheric O+ escape flux on electromagnetic energy flux and electron precipitation into the ionosphere is derived for a hypothetical ambipolar pick-up process, powered the relative motion of plasmas and neutral upper atmosphere, and by electron precipitation, at heights where the ions are magnetized but influenced by photo-ionization, collisions with gas atoms, ambipolar and centrifugal acceleration. Ion pick-up by the convection electric field produces "ring-beam" or toroidal velocity distributions, as inferred from direct plasma measurements, from observations of the associated waves, and from the spectra of incoherent radar echoes. Ring-beams are unstable to plasma wave growth, resulting in rapid relaxation via transverse velocity diffusion, into transversely accelerated ion populations. Ion escape is substantially facilitated by the ambipolar potential, but is only weakly affected by centrifugal acceleration. If, as cited simulations suggest, ion ring beams relax into non-thermal velocity distributions with characteristic speed equal to the local ion-neutral flow speed, a generalized "Jeans escape" calculation shows that the escape flux of ionospheric O+ increases with Poynting flux and with precipitating electron density in rough agreement with observations.

  1. A Network of Direct Broadcast Antenna Systems to Provide Real-Time Infrared and Microwave Sounder Data for Numerical Weather Prediction

    NASA Astrophysics Data System (ADS)

    Gumley, L.

    2013-12-01

    The Space Science and Engineering Center at the University of Wisconsin-Madison is creating a network of direct broadcast satellite data reception stations to acquire and process infrared and microwave sounder data in real-time from polar orbiting meteorological satellites and deliver the resulting products to NOAA with low latency for assimilation in NCEP numerical weather prediction models. The network will include 4 antenna sites that will be operated directly by SSEC, including Madison WI, Honolulu HI, Miami FL, and Mayaguez PR. The network will also include partner antenna sites not directly controlled by SSEC, including Corvallis OR, Monterey CA, Suitland MD, Fairbanks AK, and Guam. All of the antenna sites will have a combined X/L-band reception system capable of receiving data via direct broadcast from polar orbiting satellites including Suomi NPP and JPSS-1, Metop-A/B, POES,Terra, and Aqua. Each site will collect raw data from these satellites locally, process it to Level 1 (SDR) and Level 2 (EDR) products, and transmit the products back to SSEC for delivery to NOAA/NCEP. The primary purpose of the antenna systems is to provide real-time infrared and microwave sounder data from Metop and Suomi-NPP to NOAA to support data assimilation for NOAA/NCEP operational numerical weather prediction models. At present, NOAA/NCEP use of advanced infrared (CrIS, IASI, AIRS) and microwave (ATMS, AMSU) sounder data over North America in NWP data assimilation is limited because of the latency of the products in relation to the cutoff times for assimilation runs. This network will deliver infrared and microwave sounder data to NCEP with the lowest latency possible, via the reception and processing of data received via direct broadcast. CIMSS/SSEC is managing the procurement and installation of the antenna systems at the two new sites, and will operate the stations remotely. NOAA will establish the reception priorities (Metop and SNPP will be at the highest priority) and

  2. Ionosphere dynamics over the Southern Hemisphere during the 31 March 2001 severe magnetic storm using multi-instrument measurement data

    NASA Astrophysics Data System (ADS)

    Yizengaw, E.; Dyson, P. L.; Essex, E. A.; Moldwin, M. B.

    2005-03-01

    The effects of the 31 March 2001 severe magnetic storm on the Southern Hemisphere ionosphere have been studied using ground-based and satellite measurements. The prime goal of this comprehensive study is to track the ionospheric response from high-to-low latitude to obtain a clear understanding of storm-time ionospheric change. The study uses a combination of ionospheric Total Electron Content (TEC) obtained from GPS signal group delay and phase advance measurements, ionosonde data, and data from satellite in-situ measurements, such as the Defense Metrological Satellite Program (DMSP), TOPographic EXplorer (TOPEX), and solar wind data from the Advanced Composition Explorer (ACE). A chain of Global Positioning System (GPS) stations near the 150° E meridian has been used to give comprehensive latitude coverage extending from the cusp to the equatorial region. A tomographic inversion algorithm has been applied to the GPS TEC measurements to obtain maps of the latitudinal structure of the ionospheric during this severe magnetic storm period, enabling both the spatial and temporal response of the ionosphere to be studied. Analysis of data from several of the instruments indicates that a strong density enhancement occurred at mid-latitudes at 11:00 UT on 31 March 2001 and was followed by equatorward propagating large-scale Travelling Ionospheric Disturbances (TIDs). The tomographic reconstruction revealed important features in ionospheric structure, such as quasi-wave formations extending finger-like to higher altitudes. The most pronounced ionospheric effects of the storm occurred at high- and mid-latitudes, where strong positive disturbances occurred during the storm main phase, followed by a long lasting negative storm effect during the recovery phase. Relatively minor storm effects occurred in the equatorial region.

  3. Field-aligned electron density irregularities near 500 km Equator to polar cap topside sounder observations

    NASA Astrophysics Data System (ADS)

    Benson, R. F.

    1985-06-01

    In addition to spread F, evidence for field-aligned electron density irregularities is commonly observed on Alouette 2 topside sounder ionograms recorded near perigee (500 km). This evidence is provided by distinctive signal returns from sounder-generated Z mode waves. At low latitudes these waves become guided in wave ducts caused by field-aligned electron density irregularities and give rise to strong long-duration echoes. At high latitudes, extending well into the polar cap, these Z mode waves (and stimulated electrostatic waves at the plasma frequency) produce a series of vertical bars on the ionogram display as the satellite traverses discrete field-aligned density structures. The radio frequency (RF) noise environment to be expected in the 400 to 500 km altitude region from low to high latitudes was examined by analyzing perigee Alouette 2 topside sounder data. All observed noise bands were scaled on nearly 200 topside sounder ionograms recorded near perigee at low, mid, and high latitude telemetry stations. The minimum and maximum frequencies of each noise band were entered into a data base or computer analysis. The signals of primary interest in the perigee study were found to be sounder-generated.

  4. From Aircraft to GEO: Using Microwave Sounders to Observe the Atmosphere

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, B.; Brown, S.; Gaier, T.; Tanner, A.; Kangaslahti, P.; Lim, B.; Tanabe, J.

    2010-12-01

    Although hyperspectral infrared sounders, such as AIRS and IASI, have become important weather and climate sensors for both operational and research use, microwave sounders, in spite of their coarser spatial resolution and poorer sounding accuracy, still play a crucial role. That is because infrared sounders do not sample certain weather and climate regimes well, particularly those associated with full cloud cover and storms. In part one this paper we review recent results obtained with the High Altitude MMIC Sounding Radiometer (HAMSR), an aircraft-based microwave sounder developed at the Jet Propulsion Laboratory and recently deployed on the NASA Global Hawk unmanned aircraft as part of the NASA Genesis and Rapid Intensification Processes (GRIP) hurricane field campaign. Here the emphasis is on the benefits of the high spatial resolution that is possible with suborbital sensors. In part two we will review plans to deploy a microwave sounder on a geostationary satellite in the relatively near future, where the emphasis is on the high temporal resolution that is possible from GEO. We focus on the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) now being developed at JPL for the Precipitation and All-weather Temperature and Humidity (PATH) mission - one of the 15 missions recommended by the National Research Council in its recent “decadal survey” of Earth satellite missions.

  5. Field-aligned electron density irregularities near 500 km Equator to polar cap topside sounder observations

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1985-01-01

    In addition to spread F, evidence for field-aligned electron density irregularities is commonly observed on Alouette 2 topside sounder ionograms recorded near perigee (500 km). This evidence is provided by distinctive signal returns from sounder-generated Z mode waves. At low latitudes these waves become guided in wave ducts caused by field-aligned electron density irregularities and give rise to strong long-duration echoes. At high latitudes, extending well into the polar cap, these Z mode waves (and stimulated electrostatic waves at the plasma frequency) produce a series of vertical bars on the ionogram display as the satellite traverses discrete field-aligned density structures. The radio frequency (RF) noise environment to be expected in the 400 to 500 km altitude region from low to high latitudes was examined by analyzing perigee Alouette 2 topside sounder data. All observed noise bands were scaled on nearly 200 topside sounder ionograms recorded near perigee at low, mid, and high latitude telemetry stations. The minimum and maximum frequencies of each noise band were entered into a data base or computer analysis. The signals of primary interest in the perigee study were found to be sounder-generated.

  6. Field-aligned electron density irregularities near 500 km Equator to polar cap topside sounder observations

    SciTech Connect

    Benson, R.F.

    1985-06-01

    In addition to spread F, evidence for field-aligned electron density irregularities is commonly observed on Alouette 2 topside sounder ionograms recorded near perigee (500 km). This evidence is provided by distinctive signal returns from sounder-generated Z mode waves. At low latitudes these waves become guided in wave ducts caused by field-aligned electron density irregularities and give rise to strong long-duration echoes. At high latitudes, extending well into the polar cap, these Z mode waves (and stimulated electrostatic waves at the plasma frequency) produce a series of vertical bars on the ionogram display as the satellite traverses discrete field-aligned density structures. The radio frequency (RF) noise environment to be expected in the 400 to 500 km altitude region from low to high latitudes was examined by analyzing perigee Alouette 2 topside sounder data. All observed noise bands were scaled on nearly 200 topside sounder ionograms recorded near perigee at low, mid, and high latitude telemetry stations. The minimum and maximum frequencies of each noise band were entered into a data base or computer analysis. The signals of primary interest in the perigee study were found to be sounder-generated. 15 references.

  7. How Well Can Infrared Sounders Observe the Atmosphere and Surface Through Clouds?

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

    2010-01-01

    Infrared sounders, such as the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared sounder (CrIS), have a cloud-impenetrable disadvantage in observing the atmosphere and surface under opaque cloudy conditions. However, recent studies indicate that hyperspectral, infrared sounders have the ability to detect cloud effective-optical and microphysical properties and to penetrate optically thin clouds in observing the atmosphere and surface to a certain degree. We have developed a retrieval scheme dealing with atmospheric conditions with cloud presence. This scheme can be used to analyze the retrieval accuracy of atmospheric and surface parameters under clear and cloudy conditions. In this paper, we present the surface emissivity results derived from IASI global measurements under both clear and cloudy conditions. The accuracy of surface emissivity derived under cloudy conditions is statistically estimated in comparison with those derived under clear sky conditions. The retrieval error caused by the clouds is shown as a function of cloud optical depth, which helps us to understand how well infrared sounders can observe the atmosphere and surface through clouds.

  8. An empirical probability density distribution of planetary ionosphere storms with geomagnetic precursors

    NASA Astrophysics Data System (ADS)

    Gulyaeva, Tamara; Stanislawska, Iwona; Arikan, Feza; Arikan, Orhan

    The probability of occurrence of the positive and negative planetary ionosphere storms is evaluated using the W index maps produced from Global Ionospheric Maps of Total Electron Content, GIM-TEC, provided by Jet Propulsion Laboratory, and transformed from geographic coordinates to magnetic coordinates frame. The auroral electrojet AE index and the equatorial disturbance storm time Dst index are investigated as precursors of the global ionosphere storm. The superposed epoch analysis is performed for 77 intense storms (Dst≤-100 nT) and 227 moderate storms (-100ionosphere storm, versus AE index and Dst index. It is found that AE index better suits to serve as a precursor of the ionosphere storm than Dst index with onset of the average auroral AE storm occurring 6 h before the equatorial Dst storm onset for intense storms and 3 h in advance of moderate Dst storm. The similar space zones advancement of the ionosphere storm is observed with W index (pW+ and pW-) depicting maximum localized in the polar magnetic zone and minimum at magnetic equator. An empirical relation for pW+ and pW- with AE storm precursor is derived which enables the probability of occurrence of the ionosphere storm to be predicted with leading time of 1-2 h for the positive ionosphere storm and 9-10 h for the negative ionosphere storm. The ionosphere storm probability model is validated using data for 2 intense and 20

  9. The Radiative Consistency of Atmospheric Infrared Sounder and Moderate Resolution Imaging Spectroradiometer Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Kahn, Brian H.; Fishbein, Evan; Nasiri, Shaima L.; Eldering, Annmarie; Fetzer, Eric J.; Garay, Michael J.; Lee, Sung-Yung

    2007-01-01

    The consistency of cloud top temperature (Tc) and effective cloud fraction (f) retrieved by the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit (AMSU) observation suite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on the EOS-Aqua platform are investigated. Collocated AIRS and MODIS TC and f are compared via an 'effective scene brightness temperature' (Tb,e). Tb,e is calculated with partial field of view (FOV) contributions from TC and surface temperature (TS), weighted by f and 1-f, respectively. AIRS reports up to two cloud layers while MODIS reports up to one. However, MODIS reports TC, TS, and f at a higher spatial resolution than AIRS. As a result, pixel-scale comparisons of TC and f are difficult to interpret, demonstrating the need for alternatives such as Tb,e. AIRS-MODIS Tb,e differences ((Delta)Tb,e) for identical observing scenes are useful as a diagnostic for cloud quantity comparisons. The smallest values of DTb,e are for high and opaque clouds, with increasing scatter in (Delta)Tb,e for clouds of smaller opacity and lower altitude. A persistent positive bias in DTb,e is observed in warmer and low-latitude scenes, characterized by a mixture of MODIS CO2 slicing and 11-mm window retrievals. These scenes contain heterogeneous cloud cover, including mixtures of multilayered cloudiness and misplaced MODIS cloud top pressure. The spatial patterns of (Delta)Tb,e are systematic and do not correlate well with collocated AIRS-MODIS radiance differences, which are more random in nature and smaller in magnitude than (Delta)Tb,e. This suggests that the observed inconsistencies in AIRS and MODIS cloud fields are dominated by retrieval algorithm differences, instead of differences in the observed radiances. The results presented here have implications for the validation of cloudy satellite retrieval algorithms, and use of cloud products in quantitative analyses.

  10. Impact of Solar Wind Variability on the Magnetosphere and Ionosphere at Mars

    NASA Astrophysics Data System (ADS)

    Opgenoorth, Hermann; Andrews, David; Edberg, Niklas; Lester, Mark; Fränz, Markus; Witasse, Olivier; Morgan, David

    2013-04-01

    At planets with induced magnetospheres the coupling between the ionosphere, the small draped magnetosphere and the solar wind is very direct in comparison to Earth. On the other hand it is more complicated as the weak induced magnetosphere itself is created by and in its shape and strength dynamically depending on the prevailing Solar wind conditions. In early 2010 Mars was located behind Earth in the Solar wind. And were able to utilize coordinated data from multiple near-Earth spacecraft (Stereo, ACE) to evaluate what kind of Solar wind disturbances have passed by Earth and might hit Mars consecutively (and when). Again during February to April, 2012, Mercury, Venus, Earth and Mars have been in perfect alignments - both radially and along the Parker spiral - to study the development of Solar wind variability in the inner heliosphere, and the corresponding space weather impact at all 4 terrestrial planets. Apart from missions at Mercury - Messenger, Mars - Mars Express, Venus - Venus Express, and Earth - Cluster, Themis, SDO, ACE, Wind, SOHO... - even STEREO A and B were located at strategic locations, about 120 deg offset in either direction from SDO at 1 AU. In addition MSL contributes to this unique dataset with an operating radiation monitor en-route to Mars, located right between Earth and Mars for the period of interest. During these two periods the Mars Express mission operated in an enhanced data mode, improving coverage from space plasma instruments like ASPERA, MARSIS and MaRS. We use plasma data from the ESA Mars- Express mission (mainly from the ASPERA particle instrument and the MARSIS topside ionospheric sounder) to investigate, for a number of isolated events, how the induced magnetosphere at Mars develops and decays in response to Solar wind variability in the magnetic field, density and velocity, and what kind of ionospheric dynamics are produced in association with such events.

  11. Constellation based DORIS receiver network for ionospheric data

    NASA Astrophysics Data System (ADS)

    Rainwater, D.; Gaussiran, T.; Barnum, B.

    2011-12-01

    Study of the upper and lower atmosphere has advanced to the point where a compelling need has emerged for global real-time specification of the most important observations as inputs to climate models. For the ionosphere, plasmasphere and magnetosphere this is the local free electron density (ED); for the troposphere it is the local water vapor content (WVC). We describe a proposal made to the GEOScan geoscience collaboration for a DORIS receiver to be flown on the Iridium-NEXT constellation that would provide precise, real-time measurements of both bulk ED WVC, as well as ionospheric scintillation; and precise orbit determination to the 1-3 cm level, thus valuable to the Earth gravity science community. Iridium-NEXT is a constellation of 66 satellites in six polar orbit planes, to be deployed starting in 2015. We describe how the DORIS frequency lever arm is superior to that of GPS for ionospheric purposes, and how DORIS data is currently being used to generate TWV data sets of comparable precision to GPS and VLBI data. GEOScan data would be persistent, global and real-time. Its data would be made available publicly in near-real-time.

  12. Medium-scale traveling ionospheric disturbances by three-dimensional ionospheric GPS tomography

    NASA Astrophysics Data System (ADS)

    Chen, C. H.; Saito, A.; Lin, C. H.; Yamamoto, M.; Suzuki, S.; Seemala, G. K.

    2016-02-01

    In this study, we develop a three-dimensional ionospheric tomography with the ground-based global position system (GPS) total electron content observations. Because of the geometric limitation of GPS observation path, it is difficult to solve the ill-posed inverse problem for the ionospheric electron density. Different from methods given by pervious studies, we consider an algorithm combining the least-square method with a constraint condition, in which the gradient of electron density tends to be smooth in the horizontal direction and steep in the vicinity of the ionospheric F2 peak. This algorithm is designed to be independent of any ionospheric or plasmaspheric electron density models as the initial condition. An observation system simulation experiment method is applied to evaluate the performance of the GPS ionospheric tomography in detecting ionospheric electron density perturbation at the scale size of around 200 km in wavelength, such as the medium-scale traveling ionospheric disturbances.

  13. Federal Funding and Knowledge Growth in Ionospheric Physics, 1945-81.

    ERIC Educational Resources Information Center

    Gillmor, C. Stewart

    1986-01-01

    Presents a historical overview of developments in ionospheric physics and examines relationships between federal funding and knowledge growth in this field. Summarizes the views of ionsphere researchers on funding, the role of funding program managers, and the nature of funding agencies. Reviews advancements related to entrepreneurs and resources…

  14. Investigations of magnetosphere-ionosphere coupling relevant to operational systems. Final scientific report, 1984-1987

    SciTech Connect

    Meng, C.I.; Newell, P.T.

    1988-02-01

    Important advances were made in understanding the dynamics of the magnetosphere and its coupling to the ionosphere. Significant progress was made in the areas of polar cusp precipitation and dynamics; dayside auroral morphology and auroral boundary dynamics; polar rain; the quiescent polar cap; the physics of impulsive injection phenomena; and problems of global magnetospheric plasma transport.

  15. Assimilation of Atmospheric InfraRed Sounder (AIRS) Profiles using WRF-Var

    NASA Technical Reports Server (NTRS)

    Zavodsky, Brad; Jedlovec, Gary J.; Lapenta, William

    2008-01-01

    The Weather Research and Forecasting (WRF) model contains a three-dimensional variational (3DVAR) assimilation system (WRF-Var), which allows a user to join data from multiple sources into one coherent analysis. WRF-Var combines observations with a background field traditionally generated using a previous model forecast through minimization of a cost function. In data sparse regions, remotely-sensed observations may be able to improve analyses and produce improved forecasts. One such source comes from the Atmospheric Infrared Sounder (AIRS), which together with the Advanced Microwave Sounding Unit (AMSU), represents one of the most advanced space-based atmospheric sounding systems. The combined AIRS/AMSU system provides radiance measurements used as input to a sophisticated retrieval scheme which has been shown to produce temperature profiles with an accuracy of 1 K over 1 km layers and humidity profiles with accuracy of 15% in 2 km layers in both clear and partly cloudy conditions. The retrieval algorithm also provides estimates of the accuracy of the retrieved values at each pressure level, allowing the user to select profiles based on the required error tolerances of the application. The purpose of this paper is to describe a procedure to optimally assimilate high-resolution AIRS profile data into a regional configuration of the Advanced Research WRF (ARW) version 2.2 using WRF-Var. The paper focuses on development of background error covariances for the regional domain and background field type using gen_be and an optimal methodology for ingesting AIRS temperature and moisture profiles as separate overland and overwater retrievals with different error characteristics in the WRF-Var. The AIRS thermodynamic profiles are obtained from the version 5.0 Earth Observing System (EOS) science team retrieval algorithm and contain information about the quality of each temperature layer. The quality indicators are used to select the highest quality temperature and moisture

  16. Effects of a strong ICME on the Martian ionosphere as detected by Mars Express and Mars Odyssey

    NASA Astrophysics Data System (ADS)

    Morgan, D. D.; Diéval, C.; Gurnett, D. A.; Duru, F.; Dubinin, E. M.; Fränz, M.; Andrews, D. J.; Opgenoorth, H. J.; Uluşen, D.; Mitrofanov, I.; Plaut, J. J.

    2014-07-01

    We present evidence of a substantial ionospheric response to a strong interplanetary coronal mass ejection (ICME) detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board the Mars Express (MEX) spacecraft. A powerful ICME impacted the Martian ionosphere beginning on 5 June 2011, peaking on 6 June, and trailing off over about a week. This event caused a strong response in the charged particle detector of the High-Energy Neutron Detector (HEND) on board the Odyssey spacecraft. The ion mass spectrometer of the Analyzer of Space Plasmas and Energetic Atoms instrument on MEX detected an increase in background counts, simultaneous with the increase seen by HEND, due to the flux of solar energetic particles (SEPs) associated with the ICME. Local densities and magnetic field strengths measured by MARSIS and enhancements of 100 eV electrons denote the passing of an intense space weather event. Local density and magnetosheath electron measurements and remote soundings show compression of ionospheric plasma to lower altitudes due to increased solar wind dynamic pressure. MARSIS topside sounding of the ionosphere indicates that it is extended well beyond the terminator, to about 116° solar zenith angle, in a highly disturbed state. This extension may be due to increased ionization due to SEPs and magnetosheath electrons or to plasma transport across the terminator. The surface reflection from both ionospheric sounding and subsurface modes of the MARSIS radar was attenuated, indicating increased electron content in the Mars ionosphere at low altitudes, where the atmosphere is dense.

  17. Ionospheric signatures of gravity waves produced by the 2004 Sumatra and 2011 Tohoku tsunamis: A modeling study

    NASA Astrophysics Data System (ADS)

    Yu, Yonghui; Wang, Wenqing; Hickey, Michael P.

    2017-01-01

    Ionospheric fluctuations inferred from observations of total electron content have previously been attributed to tsunamis and have confirmed the strong coupling between Earth's ocean and ionosphere via atmospheric gravity waves (AGWs). To further advance our understanding of this wave coupling process we employ a linear full-wave model and a nonlinear time-dependent model to examine the ionospheric response to the AGW perturbations induced by the 2004 Sumatra and the 2011 Tohoku tsunamis. In the 2004 case, our modeling analyses reveal that one component of the propagating AGWs becomes dynamically unstable in the E-region ionosphere at a range exceeding 2000 km in a direction 340° clockwise from north. Another component becomes convectively unstable in the E-region ionosphere at a range exceeding 700 km in a direction 250° clockwise from north. In the 2011 case, a significant enhancement in the ionospheric disturbance occurs in a direction northwest from the epicenter about 1 h following the tsunami onset, in general agreement with observations. Our simulations also indicate that the AGW propagating toward the southeast is responsible for a traveling ionospheric disturbance that remains of an observable amplitude for over 4 h during which time it propagates horizontally almost 4000 km.

  18. Sounder-accelerated electrons radiate slow-Z-mode waves

    NASA Astrophysics Data System (ADS)

    James, G.

    During the OEDIPUS-C (OC) double-payload rocket experiment, waves were transmitted from a 19-m dipole on one subpayload and received at a distance of 1200 m on a similar dipole. Bistatic propagation was obtained in the slow-Z mode of propagation, i.e., at frequencies f in max{fc, fp} < quad f quad < quad fuh, where fc is the electron gyrofrequency, fp the plasma frequency and fuh the upper-hybrid-resonance frequency. Auroral hiss is generated in the slow-Z mode. In OC, the separation vector between the transmitter and receiver lay along a direction at about 5 from the axis of the Earth's magnetic field B. The Z-mode pulses were strong and significantly dispersed. Propagation near the upper oblique resonance cone was investigated using solutions of the complete electromagnetic hot-plasma dispersion relation. No solutions were found at the operating frequencies with the observed group delays and ray directions. An explanation has been proposed involving incoherent radiation from sounder-accelerated electrons (SAE). Published observations of SAE on OC show that the OC transmitting dipole produces strong SAE at energies from 10 eV up to 10 keV when the transmitting frequency sweeps through Z-mode frequency range. The near field of the transmitting dipole pushes SAE helically downward in the general direction of the receiver. At every instant, each SAE particle creates radiation that obeys the resonance condition f - mfc = (nf/c)cosθ Vcosα , where m is a signed integer, n the Z-mode refractive index, θ the angle between the direction of propagation of the radiation and B, V the electron speed and α its pitch angle. Using the reported SAE energies, it is found that time delays like those observed can be explained with Z-mode n and θ values, for m = 0, 1 or 2. The resonance condition and dispersion relation together require θ values near the upper-oblique resonance cone. Test-particle theory combined with the hot-plasma dispersion solution is used to predict the

  19. Magnetospheric control of the bulk ionospheric plasma

    SciTech Connect

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

    1987-01-01

    The temperature, composition, and circulation of the high-latitude, ionosphere display a marked variation with altitude, latitude, longitude, universal time, season, solar cycle, and geomagnetic activity. This variation is largely a consequence of the effect that magnetospheric electric fields, particle precipitation, and heat flows have on the ionosphere. At F-region altitudes, the entire ionosphere drifts in response to magnetospheric electric fields, with the horizontal drift generally displaying a two-cell pattern of antisunward flow over the polar cap and return flow at lower latitudes. This ionospheric motion, in combination with downward magnetospheric heat flows and ion production due to energetic-particle precipitation, act to produce interesting ionospheric features such as ion and electron temperature hot spots, plasma blobs, localized ionization troughs, and extended tongue of ionization, and anomalous F-region peak altitudes and densities. The time delay for the ionosphere to respond to changing magnetospheric conditions is a strong function of altitude and can be as long as 3 to 4 hours in the upper F-region. The ionosphere's response to changing magnetospheric conditions are described using a time-dependent high-latitude ionospheric model.

  20. Plasma interactions in the Martian Nightside Ionosphere

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Fowler, C. M.; Ergun, R.; Weber, T. D.; Andrews, D. J.; Morooka, M. W.; Delory, G. T.; Eriksson, A. I.; Mitchell, D. L.; McFadden, J. P.; Connerney, J. E. P.

    2015-12-01

    Based on measurements from a number of missions at Mars the nightside ionosphere is patchy. The new mission MAVEN dedicated to observe the upper atmosphere and the plasma interactions provides the first comprehensive observations of the low altitude nightside ionosphere. Observations show that at density gradients the plasma is unstable and significant wave power, heated/accelerated electrons, and heated ions are co-located. Below 300 km, thermal electrons (>3 eV) are observed at the gradients to low density regions. The nightside ionosphere below 180 km is thought to be maintained by electron impact ionization and therefore these regions with thermal electrons may be the primary energy source for the low altitude ionosphere. Outside of the low density regions the plasma is cold. These observations suggest that the wave heating might be the primary process in the Matrian nightside ionosphere. The characteristics of these regions associated with density gradients will be presented and discussed in this presentation.

  1. Interactions between the polar ionosphere and thermosphere

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.

    1987-01-01

    The temperature, composition and circulation of the ionosphere and thermosphere in the polar regions are closely coupled and display a marked variation with altitude, latitude, longitude, universal time, season, solar cycle, and geomagnetic activity. To a large degree, this variation is a consequence of the effect that magnetospheric electric fields, particle precipitation, and heat flows have on the ionosphere-thermosphere system. These magnetospheric processes act to produce ionospheric hot spots, plasma blobs, localized ionization troughs, extended tongues of ionization and ion composition changes. These ionospheric features then affect the thermosphere because of ion-neutral momentum and energy coupling. The resulting interactions act to modify the thermospheric circulation, composition, and temperature, and this, in turn, affects the ionosphere. However, there are significant time delays associated with the various interactions. These and other results are reviewed.

  2. Modifying the ionosphere with intense radio waves.

    PubMed

    Utlaut, W F; Cohen, R

    1971-10-15

    The ionospheric modification experiments provide an opportunity to better understand the aeronomy of the natural ionosphere and also afford the control of a naturally occurring plasma, which will make possible further progress in plasma physics. The ionospheric modification by powerful radio waves is analogous to studies of laser and microwave heating of laboratory plasmas (20). " Anomalous" reflectivity effects similar to the observed ionospheric attenuation have already been noted in plasmas modulated by microwaves, and anomalous heating may have been observed in plasmas irradiated by lasers. Contacts have now been established between the workers in these diverse areas, which span a wide range of the electromagnetic spectrum. Perhaps ionospheric modification will also be a valuable technique in radio communications.

  3. Approaches to ionospheric modelling, simulation and prediction

    NASA Astrophysics Data System (ADS)

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

    1992-08-01

    The ionosphere is a complex, multispecies, anisotropic medium that exhibits a significant variation with time, space, season, solar cycle, and geomagnetic activity. In recent years, a wide range of models have been developed in an effort to describe ionospheric behavior. The modeling efforts include: (1) empirical models based on extensive worldwide data sets; (2) simple analytical models for a restricted number of ionospheric parameters; (3) comprehensive, 3D, time-dependent models that require supercomputers; (4) spherical harmonic models based on fits to output obtained from comprehensive numerical models; and (5) ionospheric models driven by real-time magnetospheric inputs. In an effort to achieve simplicity, some of the models have been restricted to certain altitude or latitude domains, while others have been restricted to certain ionospheric parameters, such as the F-region peak density, the auroral conductivity, and the plasma temperatures. The current status of the modeling efforts is reviewed.

  4. Ionospheric modification by rocket effluents. Final report

    SciTech Connect

    Bernhardt, P.A.; Price, K.M.; da Rosa, A.V.

    1980-06-01

    This report describes experimental and theoretical studies related to ionospheric disturbances produced by rocket exhaust vapors. The purpose of our research was to estimate the ionospheric effects of the rocket launches which will be required to place the Satellite Power System (SPS) in operation. During the past year, we have developed computational tools for numerical simulation of ionospheric changes produced by the injection of rocket exhaust vapors. The theoretical work has dealt with (1) the limitations imposed by condensation phenomena in rocket exhaust; (2) complete modeling of the ionospheric depletion process including neutral gas dynamics, plasma physics, chemistry and thermal processes; and (3) the influence of the modified ionosphere on radio wave propagation. We are also reporting on electron content measurements made during the launch of HEAO-C on Sept. 20, 1979. We conclude by suggesting future experiments and areas for future research.

  5. Charged particles in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Tripathi, Sachchida

    2010-05-01

    Charged particles in Titan's ionosphere Marykutty Michael1, Sachchida Nand Tripathi1,2,3, Pratima Arya1 1Indian Institute of Technology Kanpur 2Oak Ridge Associated Universities 3NASA Goddard Space Flight Center Observations by two instruments onboard the Cassini spacecraft, Ion Neutral Mass Spectrometer (INMS) and CAssini Plasma Spectrometer (CAPS), revealed the existence of heavy hydrocarbon and nitrile species with masses of several thousand atomic mass units at altitudes of 950 - 1400 km in the atmosphere of Titan (Waite et al., 2007; Crary et al., 2009). Though these particles were believed to be molecules, they are most likely aerosols formed by the clumping of smaller molecules (Waite et al., 2009). These particles were estimated to have a density of 10-3 kg m-3 and a size of up to 256 nm. The existence of very heavy ions has also been observed by the CAPS components with a mass by charge ratio of up to 10000 (Coates et al., 2007, 2009; Sittler et al., 2009). The goal of this paper is to find out whether the so called heavy ions (or charged particles) are generated by the charge transfer of ions and electrons to the particles. The charging of these particles has been studied by using the charge balance equations that include positive ions, negative ions, electrons, neutral and charged particles. Information on the most abundant ion clusters are obtained from Vuitton et al., (2009) and Wilson and Atreya, (2004). Mass by charge ratio thus calculated will be compared with those observed by Coates et al. (2007). References: Coates AJ, et al., Discovery of heavy negative ions in Titan's ionosphere, Geophys. Res. Lett., 34:L22103, 2007. Coates AJ, et al., Heavy negative ions in titan's ionosphere: altitude and latitude dependence. Planet. Space Sci., doi:10.1016/j.pss.2009.05.009, 2009. Crary F.J., et al., Heavy ions, temperatures and winds in titan's ionosphere: Combined cassini caps and inms observations. Planet. Space Sci., doi:10.1016/j.pss.2009.09.006, 2009

  6. Ionospheric data assimilation and forecasting during storms

    NASA Astrophysics Data System (ADS)

    Chartier, Alex T.; Matsuo, Tomoko; Anderson, Jeffrey L.; Collins, Nancy; Hoar, Timothy J.; Lu, Gang; Mitchell, Cathryn N.; Coster, Anthea J.; Paxton, Larry J.; Bust, Gary S.

    2016-01-01

    Ionospheric storms can have important effects on radio communications and navigation systems. Storm time ionospheric predictions have the potential to form part of effective mitigation strategies to these problems. Ionospheric storms are caused by strong forcing from the solar wind. Electron density enhancements are driven by penetration electric fields, as well as by thermosphere-ionosphere behavior including Traveling Atmospheric Disturbances and Traveling Ionospheric Disturbances and changes to the neutral composition. This study assesses the effect on 1 h predictions of specifying initial ionospheric and thermospheric conditions using total electron content (TEC) observations under a fixed set of solar and high-latitude drivers. Prediction performance is assessed against TEC observations, incoherent scatter radar, and in situ electron density observations. Corotated TEC data provide a benchmark of forecast accuracy. The primary case study is the storm of 10 September 2005, while the anomalous storm of 21 January 2005 provides a secondary comparison. The study uses an ensemble Kalman filter constructed with the Data Assimilation Research Testbed and the Thermosphere Ionosphere Electrodynamics General Circulation Model. Maps of preprocessed, verticalized GPS TEC are assimilated, while high-latitude specifications from the Assimilative Mapping of Ionospheric Electrodynamics and solar flux observations from the Solar Extreme Ultraviolet Experiment are used to drive the model. The filter adjusts ionospheric and thermospheric parameters, making use of time-evolving covariance estimates. The approach is effective in correcting model biases but does not capture all the behavior of the storms. In particular, a ridge-like enhancement over the continental USA is not predicted, indicating the importance of predicting storm time electric field behavior to the problem of ionospheric forecasting.

  7. Methods of alleviation of ionospheric scintillation effects on digital communications

    NASA Technical Reports Server (NTRS)

    Massey, J. L.

    1974-01-01

    The degradation of the performance of digital communication systems because of ionospheric scintillation effects can be reduced either by diversity techniques or by coding. The effectiveness of traditional space-diversity, frequency-diversity and time-diversity techniques is reviewed and design considerations isolated. Time-diversity signaling is then treated as an extremely simple form of coding. More advanced coding methods, such as diffuse threshold decoding and burst-trapping decoding, which appear attractive in combatting scintillation effects are discussed and design considerations noted. Finally, adaptive coding techniques appropriate when the general state of the channel is known are discussed.

  8. The Ionospheric Forerunners of Earthquakes.*

    NASA Astrophysics Data System (ADS)

    Oraevsky, V. N.; Depueva, A. Kh.; Ruzhin, Yu. Ya.; Stefan, V.

    1996-11-01

    A comprehensive analysis of various seismoionospheric precursors was carried out. This made it possible to select three main precursor types in ionosphere characterized by location and time of appearance. It is shown that common property of all seismoionospheric precursors is the fact that horizontal dimensions of precursor observations exist within the radius of earthquake epicenter originally defined by Dobrovolsky theory for ground precursor measurement. Our argument is in favor of atmospheric electricity as a possible cause for appearance of seismoionospheric precursors. Supported in part by Tesla Labs, Inc., La Jolla, CA 92038-2946. ^1Permanent address: IZMIRAN, Troitsk, Moscow Region, Russia.

  9. 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.

  10. Saturn: atmosphere, ionosphere, and magnetosphere.

    PubMed

    Gombosi, Tamas I; Ingersoll, Andrew P

    2010-03-19

    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and magnetosphere and briefly outlines the state of our knowledge after the Cassini prime mission. The mission has addressed a host of fundamental questions: What processes control the physics, chemistry, and dynamics of the atmosphere? Where does the magnetospheric plasma come from? What are the physical processes coupling the ionosphere and magnetosphere? And, what are the rotation rates of Saturn's atmosphere and magnetosphere?

  11. New Concepts in Ionospheric Modification

    DTIC Science & Technology

    1987-04-01

    30/8 198 Arl8 15. SUPPLEMENTARY NOTATION . 17 COSATI CODES ~ .SUBJECT TERMS (Continue on revro If necessary antd identify by block number) W. FIELD...reverse it neceuarY and identif,f by block .iu"boet) Thi repor t conlsiders the ionospheric modi fication that can be produced by energetic cr ,cc pa i. I...SECURITY CLASSIFICATION OF T,4lF PAGE So Block 19 Cont’d Sregions inaccessible to a charged particle beam from the same vhce I . ’ .°° .4.o. ° 4.. *1

  12. Determination of travelling ionospheric disturbances

    NASA Technical Reports Server (NTRS)

    Degenhardt, W.; Hartmann, G. H.; Davies, K.

    1978-01-01

    A total of 35 days of Faraday rotation data was obtained from the ATS-6 radio beacon experiment operating with the closely spaced network of Elbert, Table Mountain, and Fort Morgan. The 140-MHz Faraday bandpass data are uncorrelated in the transmission range from 8 to 45 minutes. There are distinct, well correlated, and time-displaced maxima and minima that allow the calculation of the speed and direction of horizontal motions of plane fronts of disturbances in the ionosphere. For some selected events, velocities between 88 and 278 m/sec were obtained.

  13. Low and Midlatitude Ionospheric Plasma Density Irregularities and Their Effects on Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tatsuhiro; Stolle, Claudia

    2017-03-01

    Earth's magnetic field results from various internal and external sources. The electric currents in the ionosphere are major external sources of the magnetic field in the daytime. High-resolution magnetometers onboard low-Earth-orbit satellites such as CHAMP and Swarm can detect small-scale currents in the nighttime ionosphere, where plasma density gradients often become unstable and form irregular density structures. The magnetic field variations caused by the ionospheric irregularities are comparable to that of the lithospheric contribution. Two phenomena in the nighttime ionosphere that contribute to the magnetic field variation are presented: equatorial plasma bubble (EPB) and medium-scale traveling ionospheric disturbance (MSTID). EPB is formed by the generalized Rayleigh-Taylor instability over the dip equator and grows nonlinearly to as high as 2000 km apex altitude. It is characterized by deep plasma density depletions along magnetic flux tubes, where the diamagnetic effect produced by a pressure-gradient-driven current enhances the main field intensity. MSTID is a few hundred kilometer-scale disturbance in the midlatitude ionosphere generated by the coupled electrodynamics between the ionospheric E and F regions. The field-aligned currents associated with EPBs and MSTIDs also have significant signatures in the magnetic field perpendicular to the main field direction. The empirical discovery of the variations in the magnetic field due to plasma irregularities has motivated the inclusion of electrodynamics in the physical modeling of these irregularities. Through an effective comparison between the model results and observations, the physical process involved has been largely understood. The prediction of magnetic signatures due to plasma irregularities has been advanced by modeling studies, and will be helpful in interpreting magnetic field observations from satellites.

  14. Low and Midlatitude Ionospheric Plasma Density Irregularities and Their Effects on Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tatsuhiro; Stolle, Claudia

    2016-10-01

    Earth's magnetic field results from various internal and external sources. The electric currents in the ionosphere are major external sources of the magnetic field in the daytime. High-resolution magnetometers onboard low-Earth-orbit satellites such as CHAMP and Swarm can detect small-scale currents in the nighttime ionosphere, where plasma density gradients often become unstable and form irregular density structures. The magnetic field variations caused by the ionospheric irregularities are comparable to that of the lithospheric contribution. Two phenomena in the nighttime ionosphere that contribute to the magnetic field variation are presented: equatorial plasma bubble (EPB) and medium-scale traveling ionospheric disturbance (MSTID). EPB is formed by the generalized Rayleigh-Taylor instability over the dip equator and grows nonlinearly to as high as 2000 km apex altitude. It is characterized by deep plasma density depletions along magnetic flux tubes, where the diamagnetic effect produced by a pressure-gradient-driven current enhances the main field intensity. MSTID is a few hundred kilometer-scale disturbance in the midlatitude ionosphere generated by the coupled electrodynamics between the ionospheric E and F regions. The field-aligned currents associated with EPBs and MSTIDs also have significant signatures in the magnetic field perpendicular to the main field direction. The empirical discovery of the variations in the magnetic field due to plasma irregularities has motivated the inclusion of electrodynamics in the physical modeling of these irregularities. Through an effective comparison between the model results and observations, the physical process involved has been largely understood. The prediction of magnetic signatures due to plasma irregularities has been advanced by modeling studies, and will be helpful in interpreting magnetic field observations from satellites.

  15. Ionospheric Challenges for GNSS Based Augmentation Systems

    NASA Astrophysics Data System (ADS)

    Doherty, P.; Valladares, C. E.

    2007-12-01

    The ionosphere is a highly dynamic physical phenomenon that presents a variable source of error for Global Navigation Satellite System (GNSS) signals and GNSS based operational systems. The Federal Aviation Administration's (FAA) Wide-Area Augmentation System (WAAS) was designed to enhance the GNSS standard positioning service by providing additional accuracy, availability and integrity that is sufficient for use in commercial aviation. It is the first of a number of planned regional Satellite Based Augmentation Systems (SBAS). Other systems in development include the European EGNOS system, the MSAS system in Japan and the GAGAN system in India. In addition, the South American countries are investigating the feasibility of operating an SBAS system in this region. Much of the WAAS ionospheric research and development focused on defining and mitigating ionospheric challenges characteristic of the mid-latitude regions, where the ionosphere is well studied and relatively quiescent. The EGNOS and MSAS systems will primarily operate under a similarly quiescent mid-latitude ionosphere. SBAS system development in South America, India and other low-latitude regions, however, will have to contend with much more extreme conditions. These conditions include strong spatial and temporal gradients, plasma depletions and scintillation. All of these conditions have a potential to limit SBAS performance in the low latitude regions. This presentation will review the effects that the ionosphere has on the mid-latitude WAAS system. It will present the techniques that are used to mitigate ionospheric disturbances induced on the system during severe geomagnetic activity and it will quantify the effect that this activity has on system performance. The presentation will then present data from the South American Low-latitude Ionospheric Sensor Network (LISN) that can be used to infer the ionospheric effects on SBAS performance in the most challenging low-latitude ionospheric environment

  16. Regional Precipitation Forecast with Atmospheric InfraRed Sounder (AIRS) Profile Assimilation

    NASA Technical Reports Server (NTRS)

    Chou, S.-H.; Zavodsky, B. T.; Jedloved, G. J.

    2010-01-01

    Advanced technology in hyperspectral sensors such as the Atmospheric InfraRed Sounder (AIRS; Aumann et al. 2003) on NASA's polar orbiting Aqua satellite retrieve higher vertical resolution thermodynamic profiles than their predecessors due to increased spectral resolution. Although these capabilities do not replace the robust vertical resolution provided by radiosondes, they can serve as a complement to radiosondes in both space and time. These retrieved soundings can have a significant impact on weather forecasts if properly assimilated into prediction models. Several recent studies have evaluated the performance of specific operational weather forecast models when AIRS data are included in the assimilation process. LeMarshall et al. (2006) concluded that AIRS radiances significantly improved 500 hPa anomaly correlations in medium-range forecasts of the Global Forecast System (GFS) model. McCarty et al. (2009) demonstrated similar forecast improvement in 0-48 hour forecasts in an offline version of the operational North American Mesoscale (NAM) model when AIRS radiances were assimilated at the regional scale. Reale et al. (2008) showed improvements to Northern Hemisphere 500 hPa height anomaly correlations in NASA's Goddard Earth Observing System Model, Version 5 (GEOS-5) global system with the inclusion of partly cloudy AIRS temperature profiles. Singh et al. (2008) assimilated AIRS temperature and moisture profiles into a regional modeling system for a study of a heavy rainfall event during the summer monsoon season in Mumbai, India. This paper describes an approach to assimilate AIRS temperature and moisture profiles into a regional configuration of the Advanced Research Weather Research and Forecasting (WRF-ARW) model using its three-dimensional variational (3DVAR) assimilation system (WRF-Var; Barker et al. 2004). Section 2 describes the AIRS instrument and how the quality indicators are used to intelligently select the highest-quality data for assimilation

  17. Investigating Solar Wind-Magnetosphere-Ionosphere Coupling with SuperDARN and AMPERE

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Coxon, J.; Imber, S. M.; Clausen, L.; Korth, H.; Anderson, B. J.

    2013-12-01

    The dynamics of the Earth's plasma environment are driven by coupling between the solar wind, with its embedded interplanetary magnetic field, and the magnetosphere through magnetic reconnection occurring at the magnetopause. Terrestrial magnetic field lines which are connected to interplanetary space in this way are subsequently released by magnetic reconnection occurring in the magnetotail. These two processes lead to increases and decreases in the proportion of the terrestrial flux that is open, as observed in changes in the latitude of the auroral zones. A circulation of plasma and magnetic flux is effected, the Dungey cycle, with a sympathetic plasma convection signature in the ionosphere. In this talk we review recent advances of our understanding of the coupling process, provided by measurements of ionospheric convection with the Super Dual Auroral Radar Network (SuperDARN) and the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) which measures the coupling currents that transfer stress from the magnetosphere into the ionosphere.

  18. Challenges for Future UV Imaging of the Earth's Ionosphere and High Latitude Regions

    NASA Technical Reports Server (NTRS)

    Spann, James

    2006-01-01

    Large scale imaging of Geospace has played a significant role in the recent advances in the comprehension of the coupled Solar-Terrestrial System. The Earth's ionospheric far ultraviolet emissions provide a rich tapestry of observations that play a key role in sorting out the dominant mechanisms and phenomena associated with the coupling of the ionosphere and magnetosphere (MI). The MI coupling is an integral part of the Solar-Terrestrial and as such, future observations in this region should focus on understanding the coupling and the impact of solar variability. This talk will focus on the outstanding problems associated with the coupled Solar-Terrestrial system that can be best addressed using far ultraviolet imaging of the Earthls ionosphere. Challenges of global scale imaging and high-resolution imaging will be discussed and how these are driven by unresolved compelling science questions of magnetospheric configuration, and auroral dynamics.

  19. An Interaction Region Near the Top of the Ionosphere Observed at Mars and Venus

    NASA Astrophysics Data System (ADS)

    Frahm, R. A.; Winningham, J.; Sharber, J. R.; Duru, F.; Gurnett, D. A.; Lundin, R.; Coates, A. J.; Tsang, S. M.; Delva, M.; Zhang, T.

    2009-05-01

    The European Space Agency (ESA) currently operates spacecraft at both Mars (Mars Express - MEx) and at Venus (Venus Express - VEx). On both MEx and VEx is the Analyzer of Space Plasmas and Energetic Atoms (ASPERA) experiment, which measures the electron spectrum with the Electron Spectrometer (ELS) and the ion spectrum with the Ion Mass Analyzer (IMA). The MEx spacecraft also contains the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) which can derive the thermal electron density and magnetic field magnitude from its ionograms. The VEx spacecraft also contains a magnetometer (MAG) experiment. At the top of the ionosphere of Mars and Venus is a region where there is mixing between plasma from the ionosphere and plasma from the solar wind. ASPERA-3 data shows high energy strahl from the solar wind penetrating through the bow shock and magnetosheath, and into the dayside ionosphere. At the same time, plasma showing electron peaks generated by the ionization of carbon dioxide and atomic oxygen by solar He 30.4 nm penetrates into the magnetosheath. This overlap region is located where the thermal electron density at Mars derived by MARSIS decreases. This region marks the beginning of ion acceleration as ions begin to flow down the tail. This region is also observed at Venus. All three experiments show turbulence near and through the ionosphere/solar wind interaction region. In this presentation we will show examples of this transition region from both Mars and Venus.

  20. High Resolution Infrared Radiation Sounder (HIRS) for the Nimbus F Spacecraft

    NASA Technical Reports Server (NTRS)

    Koenig, E. W.

    1975-01-01

    Flown on Nimbus F in June 1975, the high resolution infrared radiation sounder (HIRS) scans with a geographical resolution of 23KM and samples radiance in seventeen selected spectral channels from visible (.7 micron) to far IR (15 micron). Vertical temperature profiles and atmospheric moisture content can be inferred from the output. System operation and test results are described.

  1. The 4-Day Wave as Obvserved from the Upper Atmosphere Research Satellite Microwave Limb Sounder

    NASA Technical Reports Server (NTRS)

    Allen, D. R.; Stanford, J. L.

    1996-01-01

    The 4-day wave is an eastward moving quasi-nondispersive feature with period near 4 days occurring near the winter polar stratopause. This paper presents evidence of the 4-day feature in Microwave Limb Sounder (MLS) temperature, geopotential height and ozone data from the late Southern winters of 1992 and 1993.

  2. Calibration of the Microwave Limb Sounder on the Upper Atmosphere Research Satellite

    NASA Technical Reports Server (NTRS)

    Jarnot, Robert R.; Waters, Joe W.

    1994-01-01

    This paper describes pre-launch radiometric and spectral calibrations of the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS). Use of in-flight data for validation or refinement of calibration is described. The estimated uncertaint in calibrated radiance from pre-launch radiometric and spectral calibration data is better than 2% in most bands.

  3. Acoustic sounder system design for measurement of optical turbulence and wind profiles

    NASA Astrophysics Data System (ADS)

    Miller, Judith E.; Eaton, Frank D.; Stokes, Sheldon S.

    2000-07-01

    An Acoustic Sounder System has been installed on the side of the cliff at North Oscura Peak, WSMR to provide important refractive index structure parameter, Cn2 data for laser propagation tests. The acoustic sounder system records echo information that is used to provide 3D wind and optical turbulence profiles. The received signal is the product of the interaction of the transmitted acoustic pulse with the small scale atmospheric temperature variations. This information is displayed as a time-height display of the signal intensity. The frequency of the received signals are processed and converted into time histories of the horizontal wind field. The data from the Acoustic Sounder is calibrated with the hot-wire anemometer temperature structure parameter (Ct2) data, and meteorological data measured locally to produce the Cn2 profile. The design and location of the Acoustic Sounder System will be discussed along with the methodology of extracting the turbulence. Many days of data have been collected and representative data will be shown.

  4. Evolution of Satellite Imagers and Sounders for Low Earth Orbit and Technology Directions at NASA

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; McClain, Charles R.

    2010-01-01

    Imagers and Sounders for Low Earth Orbit (LEO) provide fundamental global daily observations of the Earth System for scientists, researchers, and operational weather agencies. The imager provides the nominal 1-2 km spatial resolution images with global coverage in multiple spectral bands for a wide range of uses including ocean color, vegetation indices, aerosol, snow and cloud properties, and sea surface temperature. The sounder provides vertical profiles of atmospheric temperature, water vapor cloud properties, and trace gases including ozone, carbon monoxide, methane and carbon dioxide. Performance capabilities of these systems has evolved with the optical and sensing technologies of the decade. Individual detectors were incorporated on some of the first imagers and sounders that evolved to linear array technology in the '80's. Signal-to-noise constraints limited these systems to either broad spectral resolution as in the case of the imager, or low spatial resolution as in the case of the sounder. Today's area 2-dimensional large format array technology enables high spatial and high spectral resolution to be incorporated into a single instrument. This places new constraints on the design of these systems and enables new capabilities for scientists to examine the complex processes governing the Earth System.

  5. Deep convective cloud characterizations from both broadband imager and hyperspectral infrared sounder measurements

    NASA Astrophysics Data System (ADS)

    Ai, Yufei; Li, Jun; Shi, Wenjing; Schmit, Timothy J.; Cao, Changyong; Li, Wanbiao

    2017-02-01

    Deep convective storms have contributed to airplane accidents, making them a threat to aviation safety. The most common method to identify deep convective clouds (DCCs) is using the brightness temperature difference (BTD) between the atmospheric infrared (IR) window band and the water vapor (WV) absorption band. The effectiveness of the BTD method for DCC detection is highly related to the spectral resolution and signal-to-noise ratio (SNR) of the WV band. In order to understand the sensitivity of BTD to spectral resolution and SNR for DCC detection, a BTD to noise ratio method using the difference between the WV and IR window radiances is developed to assess the uncertainty of DCC identification for different instruments. We examined the case of AirAsia Flight QZ8501. The brightness temperatures (Tbs) over DCCs from this case are simulated for BTD sensitivity studies by a fast forward radiative transfer model with an opaque cloud assumption for both broadband imager (e.g., Multifunction Transport Satellite imager, MTSAT-2 imager) and hyperspectral IR sounder (e.g., Atmospheric Infrared Sounder) instruments; we also examined the relationship between the simulated Tb and the cloud top height. Results show that despite the coarser spatial resolution, BTDs measured by a hyperspectral IR sounder are much more sensitive to high cloud tops than broadband BTDs. As demonstrated in this study, a hyperspectral IR sounder can identify DCCs with better accuracy.

  6. The validation of ozone measurements from the improved stratospheric and mesospheric sounder

    NASA Technical Reports Server (NTRS)

    Connor, Brian J.; Scheuer, Christopher J.; Chu, D. A.; Remedios, John J.; Marks, C. J.; Rodgers, Clive D.; Taylor, Fredric W.

    1994-01-01

    We present preliminary results of the validation of ozone measurements from the Improved Stratospheric and Mesospheric Sounder (ISAMS). The indications are that the ISAMS provides ozone data which generally agrees with other experiments and climatological values, except in regions of large thermal gradients or high aerosol loading. Corrections for these effects will be included in future reprocessing of the data.

  7. Shallow scattering layer in the subarctic pacific ocean: detection by high-frequency echo sounder.

    PubMed

    Barraclough, W E; Lebrasseur, R J; Kennedy, O D

    1969-10-31

    Shallow scattering layers consisting mainly of Calanus cristatus were detected on a trans-Pacific crossing to depths of 60 meters with a high-frequency echo sounder. Biomass estimates of these layers indicate concentrations of zoo-plankton that are greater and more extensive than previously reported in the open ocean.

  8. Determination of film processing specifications for the Apollo 17 S-209 lunar sounder experiment

    NASA Technical Reports Server (NTRS)

    Weinstein, M. S.

    1972-01-01

    The lunar sounder is described as a radar system operating at carrier frequencies of 5, 15, and 150 MHz. The radar echoes are recorded onto Kodak type S0-394 film through the use of an optical recorder utilizing a cathode ray tube as the exposing device. A processing configuration is determined with regard to linearity, dynamic range, and noise.

  9. High-powered Radar Sounders for the Investigation of Jupiter's Icy Moons

    NASA Technical Reports Server (NTRS)

    Safaeinili, A.; Rodriguez, E.; Edelstein, Wendy

    2003-01-01

    This talk will address the main drivers in the design of a radar sounder for the JIMO mission and provide a potential solution that will optimize the chances of success in the detection of ice/water interface and sub-surface stratigraphy.

  10. Inductive ionospheric solver for magnetospheric MHD simulations

    NASA Astrophysics Data System (ADS)

    Vanhamäki, H.

    2011-01-01

    We present a new scheme for solving the ionospheric boundary conditions required in magnetospheric MHD simulations. In contrast to the electrostatic ionospheric solvers currently in use, the new solver takes ionospheric induction into account by solving Faraday's law simultaneously with Ohm's law and current continuity. From the viewpoint of an MHD simulation, the new inductive solver is similar to the electrostatic solvers, as the same input data is used (field-aligned current [FAC] and ionospheric conductances) and similar output is produced (ionospheric electric field). The inductive solver is tested using realistic, databased models of an omega-band and westward traveling surge. Although the tests were performed with local models and MHD simulations require a global ionospheric solution, we may nevertheless conclude that the new solution scheme is feasible also in practice. In the test cases the difference between static and electrodynamic solutions is up to ~10 V km-1 in certain locations, or up to 20-40% of the total electric field. This is in agreement with previous estimates. It should also be noted that if FAC is replaced by the ground magnetic field (or ionospheric equivalent current) in the input data set, exactly the same formalism can be used to construct an inductive version of the KRM method originally developed by Kamide et al. (1981).

  11. Development of two new ionospheric indices

    NASA Astrophysics Data System (ADS)

    Noguera D., Cesar O.

    The solar terrestrial environment presently is characterized by a suite of indices that represent the system dynamics and indicate the degree of space weather effects. These indices have extended heritage based on measurements that are well calibrated and readily available. Examples of these are the solar radio flux at 10.7 cm (F10.7), magnetospheric currents inferred from ground-based magnetographs (Dst), and auroral electrojet also based on ground-based magnetograms (AE family of indices). At the present time, the ionosphere dynamics and response to space weather are not characterized by a "true" ionosphere index. However, because ionospheric plasma variability is a major adverse effect on makind's space technologies, the creation of such an index may be appropriate. The major adverse effects are associated with radio wave propagation, either communication or navigation, through the ionosphere. Over the past decade, thousands of ground-based dual frequency GPS receivers have been deployed, each of which measures ionospheric total electron content (TEC) continuously in multiple directions. Hence, with the standardized formatting of these measurements and their relatively real-time nature, a unique ionospheric data stream exists from which indices can, in principle, be developed. This study is an initial exploration of how purely an ionospheric index could be derived from these GPS-TEC data. Regional versus global issues are addressed, as well as diurnal issues.

  12. Ionospheric Indices Based on GPS TEC

    NASA Astrophysics Data System (ADS)

    Noguera, C.; Sojka, J. J.; Thompson, D. C.; Schunk, R. W.

    2005-12-01

    The solar terrestrial environment is presently characterized by a suite of indices that represent the system's dynamics and indicate the degree of space weather effects. These indices an have extended heritage based on measurements that are well calibrated and readily available. Examples of these are the solar radio flux at 10.7 cm (F10.7), magnetospheric currents inferred from ground-based magnetographs (Dst), and auroral electrojet also based on ground-based magnetograms (AE family of indices). At the present time, the ionosphere's dynamics and response to space weather are not characterized by a "true" ionosphere index. However, since ionospheric plasma variability has a major adverse effect on human space technologies, the creation of such an index may be appropriate. The major adverse effects are associated with radio wave propagation through the ionosphere either communications or navigation. Over the past decade thousands of ground-based dual frequency GPS receivers have been deployed. Each of these measures ionospheric total electron content (TEC) continuously in multiple directions. Hence, with the standardized formatting of these measurements and their near real-time nature, a unique ionospheric data stream exists from which indices can, in principle, be developed. This study is an initial exploration of how a purely ionospheric index could be derived from these GPS TEC data. Regional versus global issues are addressed, as well as diurnal issues.

  13. Integrated Analysis of Data from Impending Thermosphere-Ionosphere Missions

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    2013-12-01

    Physical understanding of the thermosphere-ionosphere system, and how it couples to the atmosphere below and the magnetosphere and Sun above, has progressed past the stage where single-point or even single-satellite measurements can significantly advance the field. In order to solve outstanding problems in explaining these complex coupled systems, and to improve the numerical models that describe them, a comprehensive approach is needed. This should include: global measurements of neutral temperature, density, and composition, global measurements of the ionosphere, continuous maps of magnetospheric currents and auroral precipitation, solar EUV irradiance at high temporal and spectral resolution, and detailed observations of high- and low-latitude ion-neutral coupling processes. With remarkable serendipity, multiple agencies from multiple nations are poised to create almost all of the required observational network during the next several years. The GOLD spectrograph will image the thermosphere from geostationary orbit, while the COSMIC-2 constellation surveys the ionosphere using GPS occultation. The SWARM satellites will measure neutral density and magnetic field perturbations, as AMPERE magnetometers on the Iridium constellation map the magnetospheric current system, while the CASSIOPE satellite investigates auroral processes. The ICON Explorer will explicate atmosphere-ionosphere coupling at low latitude. SDO/EVE will continue to measure solar EUV, and ACE will (hopefully) continue to monitor the solar wind and interplanetary magnetic field. Measurements from the ground, from suborbit, and perhaps from nano/micro/cube satellites, diversify the observational possibilities. This confluence does not emerge as an explicit goal in surveys or roadmaps, but it appears to be happening anyway, so we might as well make the most of it. What are the most challenging problems that we intend to solve? How will we employ physical and data assimilation models to support those

  14. Ionospheric calibration for single frequency altimeter measurements

    NASA Technical Reports Server (NTRS)

    Schreiner, William S.; Born, George H.

    1993-01-01

    This report investigates the potential of using Global Positioning System (GPS) data and a model of the ionosphere to supply a measure of the sub-satellite Total Electron Current (TEC) of the required accuracy (10 TECU rms) for the purpose of calibrating single frequency radar altimeter measurements. Since climatological (monthly mean) models are known to be in error by as much as 50 percent, this work focused on the Parameterized Real-Time Ionospheric Specification Model (PRISM) which has the capability to improve model accuracy by ingesting (adjusting to) in situ ionospheric measurements. A set of globally distributed TEC measurements were generated using GPS data and were used as input to improve the accuracy of the PRISM model. The adjusted PRISM TEC values were compared to TOPEX dual frequency TEC measurements (which are considered truth) for a number of TOPEX sub-satellite tracks. The adjusted PRISM values generally compared to the TOPEX measurements within the 10 TECU accuracy requirements when the sub-satellite track passed within 300 to 400 km of the GPS TEC data or when the track passed through a night time ionosphere. However, when the sub-satellite points were greater than 300 to 400 km away from the GPS TEC data or when a local noon ionosphere was sampled, the adjusted PRISM values generally differed by greater than 10 TECU rms with data excursions from the TOPEX TEC measurements of as much as 40 TECU (an 8 cm path delay error at K band). Therefore, it can be concluded from this analysis that an unrealistically large number of GPS stations would be needed to predict sub-satellite TEC at the 10 TECU level in the day time ionosphere using a model such as PRISM. However, a technique currently being studied at the Jet Propulsion Laboratory (JPL) may provide a means of supplying adequate TEC data to meet the 10 TECU ionospheric correction accuracy when using a realistic number of ionospheric stations. This method involves using global GPS TEC data to

  15. Ionospheric Profiles from Ultraviolet Remote Sensing

    DTIC Science & Technology

    1998-01-01

    remote sensing of the ionosphere from orbiting space platforms. Remote sensing of the nighttime ionosphere is a relatively straightforward process due to the absence of the complications brought about by daytime solar radiation. Further, during the nighttime hours, the O(+)-H(+) transition level in both the mid- and low-latitude ionospheres lies around 750 km, which is within the range of accuracy of the path matrix inversion. The intensity of the O(+)-e(-) recombination radiation as observed from orbiting space platforms can now be used to

  16. The solar wind-magnetosphere-ionosphere system

    PubMed

    Lyon

    2000-06-16

    The solar wind, magnetosphere, and ionosphere form a single system driven by the transfer of energy and momentum from the solar wind to the magnetosphere and ionosphere. Variations in the solar wind can lead to disruptions of space- and ground-based systems caused by enhanced currents flowing into the ionosphere and increased radiation in the near-Earth environment. The coupling between the solar wind and the magnetosphere is mediated and controlled by the magnetic field in the solar wind through the process of magnetic reconnection. Understanding of the global behavior of this system has improved markedly in the recent past from coordinated observations with a constellation of satellite and ground instruments.

  17. Artificial periodic irregularities in the auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Rietveld, M. T.; Turunen, E.; Matveinen, H.; Goncharov, N. P.; Pollari, P.

    1996-12-01

    Artificial periodic irregularities (API) are produced in the ionospheric plasma by a powerful standing electromagnetic wave reflected off the F region. The resulting electron-density irregularities can scatter other high-frequency waves if the Bragg scattering condition is met. Such measurements have been performed at mid-latitudes for two decades and have been developed into a useful ionospheric diagnostic technique. We report here the first measurements from a high-latitude station, using the EISCAT heating facility near Tromsø, Norway. Both F-region and lower-altitude ionospheric echoes have been obtained, but the bulk of the data has been in the E and D regions with echoes extending down to 52-km altitude. Examples of API are shown, mainly from the D region, together with simultaneous VHF incoherent-scatter-radar (ISR) data. Vertical velocities derived from the rate of phase change during the irregularity decay are shown and compared with velocities derived from the ISR. Some of the API-derived velocities in the 75-115-km height range appear consistent with vertical neutral winds as shown by their magnitudes and by evidence of gravity waves, while other data in the 50-70-km range show an unrealistically large bias. For a comparison with ISR data it has proved difficult to get good quality data sets overlapping in height and time. The initial comparisons show some agreement, but discrepancies of several metres per second do not yet allow us to conclude that the two techniques are measuring the same quantity. The irregularity decay time-constants between about 53 and 70 km are compared with the results of an advanced ion-chemistry model, and height profiles of recorded signal power are compared with model estimates in the same altitude range. The calculated amplitude shows good agreement with the data in that the maximum occurs at about the same height as that of the measured amplitude. The calculated time-constant agrees very well with the data below 60 km but

  18. Ionosphere/thermosphere heating determined from dynamic magnetosphere-ionosphere/thermosphere coupling

    NASA Astrophysics Data System (ADS)

    Tu, Jiannan; Song, Paul; Vasyliūnas, Vytenis M.

    2011-09-01

    Ionosphere/thermosphere heating driven by magnetospheric convection is investigated through a three-fluid inductive (including Faraday's law) approach to describing magnetosphere-ionosphere/thermosphere coupling, for a 1-D stratified ionosphere/thermosphere in this initial study. It is shown that the response of the ionosphere/thermosphere and thus the heating is dynamic and height-dependent. The heating is essentially frictional in nature rather than Joule heating as commonly assumed. The heating rate reaches a quasi-steady state after about 25 Alfvén travel times. During the dynamic period, the heating can be enhanced and displays peaks at multiple times due to wave reflections. The dynamic heating rate can be more than twice greater than the quasi-steady state value. The heating is strongest in the E-layer but the heating rate per unit mass is concentrated around the F-layer peak height. This implies a potential mechanism of driving O+ upflow from O+ rich F-layer. It is shown that the ionosphere/thermosphere heating caused by the magnetosphere-ionosphere coupling can be simply evaluated through the relative velocity between the plasma and neutrals without invoking field-aligned currents, ionospheric conductance, and electric field. The present study provides understanding of the dynamic magnetosphere-ionosphere/thermosphere coupling from the ionospheric/thermospheric view in addition to magnetospheric perspectives.

  19. Ionospheric Modelling using GPS to Calibrate the MWA. II: Regional Ionospheric Modelling using GPS and GLONASS to Estimate Ionospheric Gradients

    NASA Astrophysics Data System (ADS)

    Arora, B. S.; Morgan, J.; Ord, S. M.; Tingay, S. J.; Bell, M.; Callingham, J. R.; Dwarakanath, K. S.; For, B.-Q.; Hancock, P.; Hindson, L.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kapińska, A. D.; Lenc, E.; McKinley, B.; Offringa, A. R.; Procopio, P.; Staveley-Smith, L.; Wayth, R. B.; Wu, C.; Zheng, Q.

    2016-07-01

    We estimate spatial gradients in the ionosphere using the Global Positioning System and GLONASS (Russian global navigation system) observations, utilising data from multiple Global Positioning System stations in the vicinity of Murchison Radio-astronomy Observatory. In previous work, the ionosphere was characterised using a single-station to model the ionosphere as a single layer of fixed height and this was compared with ionospheric data derived from radio astronomy observations obtained from the Murchison Widefield Array. Having made improvements to our data quality (via cycle slip detection and repair) and incorporating data from the GLONASS system, we now present a multi-station approach. These two developments significantly improve our modelling of the ionosphere. We also explore the effects of a variable-height model. We conclude that modelling the small-scale features in the ionosphere that have been observed with the MWA will require a much denser network of Global Navigation Satellite System stations than is currently available at the Murchison Radio-astronomy Observatory.

  20. Ionospheric Stimulation By High Power Radio Waves

    NASA Astrophysics Data System (ADS)

    Minami, S.; Nishino, M.; Suzuki, Y.; Sato, S.; Tanikawa, T.; Nakamura, Y.; Wong, A. Y.

    1999-01-01

    We have performed an experiment to artificially stimulate the ionosphere using higher power radio waves at the HIPAS (High Power Auroral Stimulation) facility in Alaska. A radio transmission of 2.85 MHz was made at 80 MW (ERP). Diagnostics were made at the other site located 35 km from the transmission site. The results of cross-correlating the excited HF wave and observed with an 8 channel, 30 MHz scanning cosmic radio noise absorption records revealed the excited height of 90 km. Also atmospheric pressure waves observed on the ground show evident propagation of pressure waves which are generated in the ionosphere by the high-power HF wave. The results determine the excitation height of 90 km in the ionosphere and show evidence of the pressure wave coupling between the ionosphere and the lower atmosphere for periods of 10 min

  1. Digital Ionospheric Sounding in the Arctic.

    DTIC Science & Technology

    1977-07-01

    frequency-range bin. Goose Bay vertical ionograms were scaled in terms of 23 parameters. The monthly median curves of the most important ionospheric parameters for the period March 1975 to February 1976 are presented in the report.

  2. Magnetic Fluctuations in the Martian Ionosphere

    NASA Technical Reports Server (NTRS)

    Espley, Jared

    2010-01-01

    The Martian ionosphere is influenced by both the solar wind and the regional magnetic fields present in the Martian crust. Both influences ought to cause time variable changes in the magnetic fields present in the ionosphere. I report observations of these magnetic field fluctuations in the Martian ionosphere. I use data from the Mars Global Surveyor magnetometer instrument. By using data from the aerobraking low altitude passes (approx. 200 km) I find that there are numerous fluctuations both near and far from the strong crustal sources. Using data from the 400 km altitude mapping phase (which is near the topside of the primary ionosphere), I look at the comparative strength of the fluctuations relative to the solar wind and temporal variations. I discuss which wave modes and instabilities could be contributing to these fluctuations. I also discuss the implications of these fluctuations for understanding energy transfer in the Martian system and the effects on atmospheric escape.

  3. Space weather. Ionospheric control of magnetotail reconnection.

    PubMed

    Lotko, William; Smith, Ryan H; Zhang, Binzheng; Ouellette, Jeremy E; Brambles, Oliver J; Lyon, John G

    2014-07-11

    Observed distributions of high-speed plasma flows at distances of 10 to 30 Earth radii (R(E)) in Earth's magnetotail neutral sheet are highly skewed toward the premidnight sector. The flows are a product of the magnetic reconnection process that converts magnetic energy stored in the magnetotail into plasma kinetic and thermal energy. We show, using global numerical simulations, that the electrodynamic interaction between Earth's magnetosphere and ionosphere produces an asymmetry consistent with observed distributions in nightside reconnection and plasmasheet flows and in accompanying ionospheric convection. The primary causal agent is the meridional gradient in the ionospheric Hall conductance which, through the Cowling effect, regulates the distribution of electrical currents flowing within and between the ionosphere and magnetotail.

  4. On the Ionospheric Holes of Venus

    NASA Astrophysics Data System (ADS)

    Collinson, G.; Fedorov, A.; Futaana, Y.; Masunaga, K.; Hartle, R. E.; Stenberg, G.; Budnik, E.; Grebowsky, J. M.; Holmstrom, M.; andre, N.; Barabash, S. V.; Zhang, T.

    2013-12-01

    One of the most intriguing unsolved mysteries that endures from the Pioneer Venus Orbiter is that of ~1000km wide ``Holes" in the nightside Ionosphere. The phenomena remains unexplained, despite their frequent observation during the first three years of the mission, and more than thirty years having elapsed since their first description in the literature. We present new observations by the ESA Venus Express of Ionospheric Holes at very high altitudes, providing us with the opportunity to study this fascinating phenomena with modern instrumentation. We discuss the insight that these new data give us into the effect of Ionospheric Holes on atmospheric escape, and the evidence that suggests that Ionospheric Holes are due to an internal planetary magnetic field.

  5. 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.

  6. Pulsating aurora: The importance of the ionosphere

    SciTech Connect

    Stenbaek-Nielsen, H.C.

    1980-05-01

    A number of different, but mainly optical, observations made in pulsating auroras are presented. These observations indicate that active ionospheric processes are likely to play an important role in causing and/or modifying pulsating aurora.

  7. Thermospheric storms and related ionospheric effects

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Spencer, N. W.

    1976-01-01

    A comparative study of thermospheric storms for equinox and winter conditions is presented based on neutral-composition measurements from the Aeros-A neutral-atmosphere temperature experiment. The main features of the two storms as inferred from changes in N2, Ar, He, and O are described, and their implications for current theories of thermospheric storms are discussed. On the basis of the study of the F-region critical frequency measured from a chain of ground-based ionospheric stations during the two storm periods, the general characteristics of the ionospheric storms and the traveling ionospheric disturbances are described. It is suggested that the positive and negative phases of ionospheric storms are different manifestations of thermospheric storms.

  8. Magnetic Earth Ionosphere Resonant Frequencies

    NASA Technical Reports Server (NTRS)

    Spaniol, Craig

    1994-01-01

    The Community College Division is pleased to report progress of NASA funded research at West Virginia State College. During this reporting period, the project research group has continued with activities to develop instrumentation capability designed to monitor resonant cavity frequencies in the atmospheric region between the Earth's surface and the ionosphere. In addition, the project's principal investigator, Dr. Craig Spaniol, and NASA technical officer, Dr. John Sutton, have written and published technical papers intended to expand the scientific and technical framework needed for project research. This research continues to provide an excellent example of government and education working together to provide significant research in the college environment. This cooperative effort has provided many students with technical project work which compliments their education.

  9. Remote Sensing of Ionosphere by IONOLAB Group

    NASA Astrophysics Data System (ADS)

    Arikan, Feza

    2016-07-01

    Ionosphere is a temporally and spatially varying, dispersive, anisotropic and inhomogeneous medium that is characterized primarily by its electron density distribution. Electron density is a complex function of spatial and temporal variations of solar, geomagnetic, and seismic activities. Ionosphere is the main source of error for navigation and positioning systems and satellite communication. Therefore, characterization and constant monitoring of variability of the ionosphere is of utmost importance for the performance improvement of these systems. Since ionospheric electron density is not a directly measurable quantity, an important derivable parameter is the Total Electron Content (TEC), which is used widely to characterize the ionosphere. TEC is proportional to the total number of electrons on a line crossing the atmosphere. IONOLAB is a research group is formed by Hacettepe University, Bilkent University and Kastamonu University, Turkey gathered to handle the challenges of the ionosphere using state-of-the-art remote sensing and signal processing techniques. IONOLAB group provides unique space weather services of IONOLAB-TEC, International Reference Ionosphere extended to Plasmasphere (IRI-Plas) model based IRI-Plas-MAP, IRI-Plas-STEC and Online IRI-Plas-2015 model at www.ionolab.org. IONOLAB group has been working for imaging and monitoring of ionospheric structure for the last 15 years. TEC is estimated from dual frequency GPS receivers as IONOLAB-TEC using IONOLAB-BIAS. For high spatio-temporal resolution 2-D imaging or mapping, IONOLAB-MAP algorithm is developed that uses automated Universal Kriging or Ordinary Kriging in which the experimental semivariogram is fitted to Matern Function with Particle Swarm Optimization (PSO). For 3-D imaging of ionosphere and 1-D vertical profiles of electron density, state-of-the-art IRI-Plas model based IONOLAB-CIT algorithm is developed for regional reconstruction that employs Kalman Filters for state

  10. Upper tropospheric cloud systems derived from IR sounders: properties of cirrus anvils in the tropics

    NASA Astrophysics Data System (ADS)

    Protopapadaki, Sofia E.; Stubenrauch, Claudia J.; Feofilov, Artem G.

    2017-03-01

    Representing about 30 % of the Earth's total cloud cover, upper tropospheric clouds play a crucial role in the climate system by modulating the Earth's energy budget and heat transport. When originating from convection, they often form organized systems. The high spectral resolution of the Atmospheric Infrared Sounder (AIRS) allows reliable cirrus identification, both from day and nighttime observations. Tropical upper tropospheric cloud systems have been analyzed by using a spatial composite technique on the retrieved cloud pressure of AIRS data. Cloud emissivity is used to distinguish convective core, cirrus and thin cirrus anvil within these systems. A comparison with simultaneous precipitation data from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) shows that, for tropical upper tropospheric clouds, a cloud emissivity close to 1 is strongly linked to a high rain rate, leading to a proxy to identify convective cores. Combining AIRS cloud data with this cloud system approach, using physical variables, provides a new opportunity to relate the properties of the anvils, including also the thinner cirrus, to the convective cores. It also distinguishes convective cloud systems from isolated cirrus systems. Deep convective cloud systems, covering 15 % of the tropics, are further distinguished into single-core and multi-core systems. Though AIRS samples the tropics only twice per day, the evolution of longer-living convective systems can be still statistically captured, and we were able to select relatively mature single-core convective systems by using the fraction of convective core area within the cloud systems as a proxy for maturity. For these systems, we have demonstrated that the physical properties of the anvils are related to convective depth, indicated by the minimum retrieved cloud temperature within the convective core. Our analyses show that the size of the systems does in general increase with convective depth, though for

  11. Nighttime Cirrus Detection using Atmospheric Infrared Sounder Window Channels and Total Column Water Vapor

    NASA Technical Reports Server (NTRS)

    Kahn, Brian H.; Liou, Kuo Nan; Lee, Sung-Yung; Fishbein, Evan F.; DeSouza-Machado, Sergio; Eldering, Annmarie; Fetzer, Eric J.; Hannon, Scott E.; Strow, L. Larrabee

    2005-01-01

    A method of cirrus detection at nighttime is presented that utilizes 3.8 and 10.4 (micro)m infrared (IR) window brightness temperature differences (dBT) and total column precipitable water (PW) measurements. This technique is applied to the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit A (AMSU-A) instrument suite on board EOS-Aqua, where dBT is determined from sets of carefully selected AIRS window channels, while PW is derived from the synergistic AIRS and AMSU-A water vapor retrievals. Simulated and observed dBT for a particular value of PW are not constant; several physical factors impact dBT, including the variability in temperature and relative humidity profiles, surface emissivity, instrument noise, and skin/ near-surface air temperature differences. We simulate clear-sky dBT over a realistic range of PWs using 8350 radiosondes that have varying temperature and relative humidity profiles. Thresholds between cloudy and uncertain sky conditions are derived once the scatter in the clear-sky dBT is determined. Simulations of optically thin cirrus indicate that this technique is most sensitive to cirrus optical depth in the 10 (micro)m window of 0.1-0.15 or greater over the tropical and subtropical oceans, where surface emissivity and skin/near-surface air temperature impacts on the IR radiances are minimal. The method at present is generally valid over oceanic regions only, specifically, the tropics and subtropics. The detection of thin cirrus, and other cloud types, is validated using observations at the Atmospheric Radiation Measurement (ARM) program site located at Manus Island in the tropical western Pacific for 89 coincident EOS-Aqua overpasses. Even though the emphasis of this work is on the detection of thin cirrus at nighttime, this technique is sensitive to a broad cloud morphology. The cloud detection technique agrees with ARM-detected clouds 82-84% of the time, which include thin cirrus, as well as other cloud types. Most of

  12. A Model of Callisto's Ionosphere

    NASA Astrophysics Data System (ADS)

    Hartkorn, O. A.; Saur, J.; Bloecker, A.; Strobel, D. F.; Simon, S.

    2014-12-01

    We develop a model of the ionosphere of Jupiter's moon Callisto, where we assume a stationary balance between sources and sinks of electrons and electron energy. Hence, effects of electron transport and electron energy transport are neglected. At Callisto, the production of electrons and electron energy is basically driven by photoionization, which is implemented using the EUVAC model for solar activity. Dissociative recombination is the main electron loss process, whereas electron energy loss is further driven by dissociation, electron impact ionization as well as vibrational and rotational excitations of neutral atmospheric particles. All these effects are incorporated within our model by considering the associated cross sections. The neutral atmosphere is assumed to be stationary and consists of molecular oxygen with a column density of 3 to 4 x 1020 m-2 (e.g. Kliore et al. (2002), Liang et al. (2005)). Our results can be compared to radio occultation observations of four Galileo spacecraft flybys reported by Kliore et al. (2002), which shows that this simple model can explain the general pattern of the observational data. Indeed, our results indicate that the detection of enhanced electron densities is very sensitive to the exact position of the tangential point of the radio occultation method. Our model shows that photoionization produces a strong asymmetry of the electron density distribution between day and night-side of the moon. Further, model results for the electron energy allow for an estimation of the day glow of Callisto's atmosphere. This can be compared to HST observations (Strobel et al. (2002)) in order to evaluate the density of the neutral oxygen atmosphere. Future studies imply the modeling of the modification of the ionospheric structure through interaction with upstreaming jovian magnetospheric plasma.

  13. Artificial Aurora and Ionospheric Heating by HAARP

    NASA Astrophysics Data System (ADS)

    Hadavandkhani, S.; Nikouravan, Bijan; Ghazimaghrebi, F.

    2016-08-01

    A recent experiment was achieved at HAARP to study the scaling of the ionospherically generated ELF signal with power transmitted from the high frequency (HF) array. The results were in excellent agreement with computer simulations. The outcomes approving that the ELF power increases with the square of the incident HF power. This paper present a review on the situation of the ionized particles in Ionospheric layer when stimulated by artificial an ELF and VLF external high energy radio waves.

  14. Studies of Ionospheric Irregularities: Origins and Effects

    DTIC Science & Technology

    2007-09-30

    and Ionospheric Scintillations that can be found at: GPS and ionospheric scintillations, P.M. Kintner, B.M. Ledvina , and E.R. de Paula, Space... Ledvina , and P.M. Kintner, Measurements of equatorial scintillations on the WAAS satellite signal, Radio Sci., submitted, 2005. [refereed] 7...Adv. Space Res., 31(3), 741-747, 2003. [refereed] Humphreys, T.E., B.M. Ledvina , M.L. Psiaki, A.P. Cerruti, and P.M. Kintner, Analysis of

  15. Ionospheric true height profiles from oblique ionograms

    SciTech Connect

    Reilly, M.H.

    1985-06-01

    An improved direct technique in which HF oblique ionograms are reduced to ionospheric true height profiles is introduced. The benefits of this method result principally from the use of a more accurate Breit-Tuve relation to curved earth and ionosphere geometries. By comparing the results of calculations on known cases, the extent of improvement with this technique relative to the techniques by Gething and Maliphant (1967), George (1970), and Smith (1970), is demonstrated. 14 references.

  16. Digital processing of ionospheric electron content data

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.

    1979-01-01

    Ionospheric electron content data contain periodicities that are produced by a diversity of sources including hydromagnetic waves, gravity waves, and lunar tides. Often these periodicities are masked by the strong daily variation in the data. Digital filtering can be used to isolate the weaker components. The filtered data can then be further processed to provide estimates of the source properties. In addition, homomorphic filtering may be used to identify nonlinear interactions in the ionosphere.

  17. Tsunamis warning from space :Ionosphere seismology

    SciTech Connect

    Larmat, Carene

    2012-09-04

    Ionosphere is the layer of the atmosphere from about 85 to 600km containing electrons and electrically charged atoms that are produced by solar radiation. Perturbations - layering affected by day and night, X-rays and high-energy protons from the solar flares, geomagnetic storms, lightning, drivers-from-below. Strategic for radio-wave transmission. This project discusses the inversion of ionosphere signals, tsunami wave amplitude and coupling parameters, which improves tsunami warning systems.

  18. The Advanced Mars Climate Sounder (AMCS) - A Proven Atmospheric Profiler for Future Mars Orbiters

    NASA Astrophysics Data System (ADS)

    Kleinboehl, A.; Schofield, J. T.; Kass, D. M.; McCleese, D. J.

    2016-10-01

    We describe a mature, low-cost, and low-risk infrared atmospheric profiler based on MRO/MCS heritage for measuring atmospheric temperature, dust, water ice, carbon dioxide ice, and water vapor on a future Mars orbiter mission.

  19. MARSIS remote sounding of localized density structures in the dayside Martian ionosphere: A study of controlling parameters

    NASA Astrophysics Data System (ADS)

    Diéval, C.; Andrews, D. J.; Morgan, D. D.; Brain, D. A.; Gurnett, D. A.

    2015-09-01

    Enhanced topside electron densities in the dayside Martian ionosphere have been repetitively observed in areas of near-radial crustal magnetic fields, for periods of tens of days, indicating their long-term spatial and temporal stability despite changing solar wind conditions. We perform a statistical study of these density structures using the ionospheric mode of the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) onboard Mars Express. We estimate the apparent extents of these structures relative to the altitude of the surrounding ionosphere. The apex of the density structures often lies higher than the surrounding ionosphere (median vertical extent of 18 km), which indicates upwellings. These structures are much wider than they are high, with latitudinal scales of several degrees. The radar reflector regions are observed above both moderate and strong magnetic anomalies, and their precise locations and latitudinal extents match quite well with the locations and latitudinal extents of magnetic structures of given magnetic polarity (oblique to vertical fields), which happen to be regions where the field lines are open part of the time. The majority of the density structures occur in regions where ionospheric plasma is dominant, indicating closed field regions shielded from shocked solar wind plasma.

  20. Nitric oxide densities and their diurnal asymmetry in the upper middle atmosphere as revealed by ionospheric measurements

    NASA Astrophysics Data System (ADS)

    Laštovička, J.

    2001-01-01

    The nitric oxide (NO) density is of principal importance for the lower ionosphere as it is the source of the main ionized component. The mesospheric NO density climatology based on HALOE//UARS measurements (Siskind et al., Advances in Space Research 21 (1998) 1353-1362) and a comparison of the HALOE NO density data with some ionospheric data (Friedrich et al., Journal of Atmospheric and Solar-Terrestrial Physics 60 (1998) 1445-1457) revealed, among others, a large ``puzzling'' diurnal asymmetry of the NO density. In this paper, the existence of a diurnal asymmetry of the NO density is confirmed by independent data and is extended from the sunrise//sunset HALOE data to the entire daytime. We analyzed multi-frequency radio wave absorption measurements in the lower ionosphere over Central Europe, partly together with solar Lyman-/α and X-ray fluxes, in order to estimate the NO density. The results show that our ``ionospheric'' NO densities are comparable to, or somewhat higher than, the climatological NO densities of Siskind et al. (1998). They also show that the diurnal asymmetry in summer is a stable and regular feature of the lower ionosphere throughout the daytime, and that there is a substantial diurnal asymmetry in the NO density in the upper middle atmosphere that coincides with that revealed by the HALOE data and which is responsible for the asymmetry in the lower ionosphere.

  1. Measurement of middle and upper atmospheric horizontal winds with a submillimeter/THz limb sounder: results from JEM/SMILES and simulation study for SMILES-2

    NASA Astrophysics Data System (ADS)

    Baron, Philippe; Manago, Naohiro; Ozeki, Hiroyuki; Yoshihisa, Irimajiri; Donal, Murtagh; Yoshinori, Uzawa; Satoshi, Ochiai; Masato, Shiotani; Makoto, Suzuki

    2016-04-01

    In a near future, ESA will launch the Atmospheric Dynamics Mission (ADM) equipped with a lidar for measuring tropospheric and lower stratospheric winds. NASA will continue a long-term series of upper atmospheric wind measurements (altitudes >80 km) with the new Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) on the Ionospheric Connection Explorer (ICON) satellite. No mission is planned to observe winds in the middle atmosphere (30-80 km), though they are recognized as essential parameters for understanding atmospheric dynamics and the vertical coupling between atmospheric regions. They are also promising data for improving long-term weather forecast and climate modelling. It has been demonstrated with the Superconducting Submillimeter Wave Limb Emission Sounder (SMILES, Oct 2009 - Apr 2010) that a 4-K cooled microwave radiometer can provide data to fill the altitude gap in the wind measurements. Its possible successor named SMILES-2, is being designed in Japan for the study of the middle and upper atmospheric chemistry and dynamics (O3, H2O, T, atomic O, OH, HO2, ClO, BrO, ...). If realized, the instrument will measure sub-millimeter and THz molecular spectral lines (616-150 μm) with high sensitivity and frequency resolution. The SMILES-2 characteristics are very well suited for horizontal wind observations between 20 km to more than 160 km. The best performances are found between 35-90 km where the retrieval precision is better than 3 m/s for a vertical resolution of 2-3 km [1]. In this presentation, we summarize the results obtained from SMILES and assess the measurement performances of SMILES-2 to measure horizontal winds. [1] P. Baron, N. Manago, H. Ozeki, Y. Irimajiri, D. Murtagh, Y. Uzawa, S. Ochiai, M. Shiotani, M. Suzuki: "Measurement of stratospheric and mesospheric winds with a SubMillimeter wave limb sounder: Results from JEM/SMILES and simulation study for SMILES-2"; Proc. of SPIE Remote sensing, 96390N-96390N-20

  2. Ionospheric Response Due to Seismic Activity

    NASA Astrophysics Data System (ADS)

    Sharma, Dinesh Kumar

    2016-07-01

    Signatures of the seismic activity in the ionospheric F2 region have been studied by analyzing the measurement of electron and ion temperatures during the occurrence of earthquake. The ionospheric electron and ion temperatures data recorded by the RPA payload aboard the Indian SROSS-C2 satellite during the period from January 1995 to December 2000 were used for the altitude range 430-630 km over Indian region. The normal day's electron and ion temperatures have been compared to the temperatures recorded during the seismic activity. The details of seismic events were obtained from USGS earthquake data information website. It has been found that the average electron temperature is enhanced during the occurrence of earthquakes by 1.2 to 1.5 times and this enhancement was for ion temperature ranging from 1.1to 1.3 times over the normal day's average temperatures. The above careful quantitative analysis of ionospheric electron and ion temperatures data shows the consistent enhancement in the ionospheric electron and ion temperatures. It is expected that the seismogenic vertical electrical field propagates up to the ionospheric heights and induces Joule heating that may cause the enhancement in ionospheric temperatures.

  3. Computerized ionospheric tomography based on geosynchronous SAR

    NASA Astrophysics Data System (ADS)

    Hu, Cheng; Tian, Ye; Dong, Xichao; Wang, Rui; Long, Teng

    2017-02-01

    Computerized ionospheric tomography (CIT) based on spaceborne synthetic aperture radar (SAR) is an emerging technique to construct the three-dimensional (3-D) image of ionosphere. The current studies are all based on the Low Earth Orbit synthetic aperture radar (LEO SAR) which is limited by long repeat period and small coverage. In this paper, a novel ionospheric 3-D CIT technique based on geosynchronous SAR (GEO SAR) is put forward. First, several influences of complex atmospheric environment on GEO SAR focusing are detailedly analyzed, including background ionosphere and multiple scattering effects (induced by turbulent ionosphere), tropospheric effects, and random noises. Then the corresponding GEO SAR signal model is constructed with consideration of the temporal-variant background ionosphere within the GEO SAR long integration time (typically 100 s to 1000 s level). Concurrently, an accurate total electron content (TEC) retrieval method based on GEO SAR data is put forward through subband division in range and subaperture division in azimuth, obtaining variant TEC value with respect to the azimuth time. The processing steps of GEO SAR CIT are given and discussed. Owing to the short repeat period and large coverage area, GEO SAR CIT has potentials of covering the specific space continuously and completely and resultantly has excellent real-time performance. Finally, the TEC retrieval and GEO SAR CIT construction are performed by employing a numerical study based on the meteorological data. The feasibility and correctness of the proposed methods are verified.

  4. Local ionospheric corrections derived from GNSS - A case study with TerraSAR-X

    NASA Astrophysics Data System (ADS)

    Gisinger, Christoph; Balss, Ulrich; Cong, Xiao Ying; Steigenberger, Peter; Eineder, Michael; Pail, Roland; Hugentobler, Urs

    2013-04-01

    Germany's synthetic aperture radar (SAR) satellites TerraSAR-X and TanDEM-X belong to the latest generation of radar satellites which have moved radar remote sensing to a new level. Besides being an all weather and all day imaging system, radar remote sensing offers various advanced methods like SAR interferometry or persistent scatterer interferometry that exploit magnitude and phase information of the radar signal. In order to achieve centimeter to millimeter accuracy with these advanced methods, all occurring error contributions (internal signal delay, orbit, troposphere, ionosphere, solid earth tides, loading effects, ...) have to be taken into account by applying appropriate corrections. Within the project DLR@Uni funded by the German Helmholtz Association HGF, an experimental framework at Wettzell station has been set up to perform a detailed analysis of all the corrections required for high resolution radar satellites and to achieve the goal of a 1cm precision level for absolute radar coordinates. This framework involves a 1.5 meter corner reflector (CR), a 1.5 year series of data takes from TerraSAR-X, and it makes use of the multi-sensor environment of Wettzell station. Besides Satellite Laser Ranging (SLR) for orbit assessment and the local geodetic network to control the CR reference coordinates, the Wettzell GNSS receivers are used for generating tropospheric and ionospheric corrections. By comparing the reference radar times (range and azimuth) available from geodetic survey with those from the TerraSAR-X data takes, the quality of the corrections can be investigated. Although often being considered negligible for X-band observations, the conducted experiment has clearly shown the necessity for ionospheric corrections, if the capabilities of current SAR satellites are to be fully exploited. For every TerraSAR-X data take, the ionospheric impact was derived from the geometry-free linear combination of the GNSS measurements and modeled in terms of

  5. Validation of the Atmospheric Infrared Sounder Water Vapor Retrievals Using Global Positioning System: Case Study in South Korea

    NASA Astrophysics Data System (ADS)

    Won, Jihye; Park, Kwan-Dong; Kim, Dusik; Ha, Jihyun

    2011-12-01

    The atmospheric infrared sounder (AIRS) sensor loaded on the Aqua satellite observes the global vertical structure of atmosphere and enables verification of the water vapor distribution over the entire area of South Korea. In this study, we performed a comparative analysis of the accuracy of the total precipitable water (TPW) provided as the AIRS level 2 standard retrieval product by Jet Propulsion Laboratory (JPL) over the South Korean area using the global positioning system (GPS) TPW data. The analysis TPW for the period of one year in 2008 showed that the accuracy of the data produced by the combination of the Advanced Microwave Sounding Unit sensor with the AIRS sensor to correct the effect of clouds (AIRS-X) was higher than that of the AIRS IR-only data (AIRS-I). The annual means of the root mean square error with reference to the GPS data were 5.2 kg/m2 and 4.3 kg/m2 for AIRS-I and AIRS-X, respectively. The accuracy of AIRS-X was higher in summer than in winter while measurement values of AIRS-I and AIRS-X were lower than those of GPS TPW to some extent.

  6. Review and perspectives: Understanding natural-hazards-generated ionospheric perturbations using GPS measurements and coupled modeling

    NASA Astrophysics Data System (ADS)

    Komjathy, Attila; Yang, Yu-Ming; Meng, Xing; Verkhoglyadova, Olga; Mannucci, Anthony J.; Langley, Richard B.

    2016-07-01

    Natural hazards including earthquakes, volcanic eruptions, and tsunamis have been significant threats to humans throughout recorded history. Global navigation satellite systems (GNSS; including the Global Positioning System (GPS)) receivers have become primary sensors to measure signatures associated with natural hazards. These signatures typically include GPS-derived seismic deformation measurements, coseismic vertical displacements, and real-time GPS-derived ocean buoy positioning estimates. Another way to use GPS observables is to compute the ionospheric total electron content (TEC) to measure, model, and monitor postseismic ionospheric disturbances caused by, e.g., earthquakes, volcanic eruptions, and tsunamis. In this paper, we review research progress at the Jet Propulsion Laboratory and elsewhere using examples of ground-based and spaceborne observation of natural hazards that generated TEC perturbations. We present results for state-of-the-art imaging using ground-based and spaceborne ionospheric measurements and coupled atmosphere-ionosphere modeling of ionospheric TEC perturbations. We also report advancements and chart future directions in modeling and inversion techniques to estimate tsunami wave heights and ground surface displacements using TEC measurements and error estimates. Our initial retrievals strongly suggest that both ground-based and spaceborne GPS remote sensing techniques could play a critical role in detection and imaging of the upper atmosphere signatures of natural hazards including earthquakes and tsunamis. We found that combining ground-based and spaceborne measurements may be crucial in estimating critical geophysical parameters such as tsunami wave heights and ground surface displacements using TEC observations. The GNSS-based remote sensing of natural-hazard-induced ionospheric disturbances could be applied to and used in operational tsunami and earthquake early warning systems.

  7. Electric Field Double Probe Measurements for Ionospheric Space Plasma Experiments

    NASA Technical Reports Server (NTRS)

    Pfaff, R.

    1999-01-01

    Double probes represent a well-proven technique for gathering high quality DC and AC electric field measurements in a variety of space plasma regimes including the magnetosphere, ionosphere, and mesosphere. Such experiments have been successfully flown on a variety of spacecraft including sounding rockets and satellites. Typical instrument designs involve a series of trades, depending on the science objectives, type of platform (e.g., spinning or 3-axis stabilized), expected plasma regime where the measurements will be made, available telemetry, budget, etc. In general, ionospheric DC electric field instruments that achieve accuracies of 0.1 mV/m or better, place spherical sensors at large distances (10m or more) from the spacecraft body in order to extend well beyond the spacecraft wake and sheath and to achieve large signal-to-noise ratios for DC and long wavelength measurements. Additional sets of sensors inboard of the primary, outermost sensors provide useful additional information, both for diagnostics of the plasma contact potentials, which particularly enhance the DC electric field measurements on non-spinning spacecraft, and for wavelength and phase velocity measurements that use the spaced receiver or "interferometer" technique. Accurate attitude knowledge enables B times V contributions to be subtracted from the measured potentials, and permits the measured components to be rotated into meaningful geophysical reference frames. We review the measurement technique for both DC and wave electric field measurements in the ionosphere discussing recent advances involving high resolution burst memories, multiple baseline double probes, new sensor surface materials, biasing techniques, and other considerations.

  8. Testing Ionospheric Faraday Rotation Corrections in CASA

    NASA Astrophysics Data System (ADS)

    Kooi, Jason E.; Moellenbrock, George

    2015-04-01

    The Earth’s ionosphere introduces direction- and time-dependent effects over a range of physical and temporal scales and so is a major source for unmodeled phase offsets for low frequency radioastronomical observations. Ionospheric effects are often the limiting factor to making sensitive radioastronomical measurements to probe the solar corona or coronal mass ejections at low frequencies (< 5 GHz). It has become common practice to use global ionospheric models derived from the Global Positioning System (GPS) to provide a means of externally calibrating low frequency data. We have developed a new calibration algorithm in the Common Astronomy Software Applications (CASA) package. CASA, which was developed to meet the data post-processing needs of next generation telescopes such as the Karl G. Jansky Very Large Array (VLA), did not previously have the capability to mitigate ionospheric effects. This algorithm uses GPS-based global ionosphere maps to mitigate the first and second order ionospheric effects (dispersion delay and Faraday rotation, respectively). We investigated several data centers as potential sources for global ionospheric models and chose the International Global Navigation Satellite System Service data product because data from other sources are generally too sparse to use without additional interpolation schemes. This implementation of ionospheric corrections in CASA has been tested on several sets of VLA observations and all of them showed a significant reduction of the dispersion delay. In order to rigorously test CASA’s ability to mitigate ionospheric Faraday rotation, we made VLA full-polarization observations of the standard VLA phase calibrators J0359+5057 and J0423+4150 in August 2014, using L band (1 - 2 GHz), S band (2 - 4 GHz), and C band (4 - 6 GHz) frequencies in the D array configuration. The observations were 4 hours in duration, beginning near local sunrise. In this paper, we give a general description of how these corrections are

  9. Heat balance of the ionosphere - Implications for the International Reference Ionosphere

    NASA Technical Reports Server (NTRS)

    Bilitza, D.

    1985-01-01

    Theoretical considerations can be helpful tools in modeling ionospheric parameters in regions and for times where not enough experimental data are available. This study asks whether results of heat balance calculations should be introduced to supplement the data base for the International Reference Ionosphere. The present status of the theoretical understanding is discussed and the influence of the following unresolved or neglected times are examined: (1) electron heating rate, (2) electron cooling by fine structure excitation of atomic oxygen, and (3) height-dependent Coulomb Logarithm. The ambiguity introduced by these terms leads to up to 30 percent uncertainty in the electron temperature of the lower ionosphere. The electron temperature in the upper ionosphere is largely determined by heat conduction from above and depends critically on the conditions assumed at the boundary between ionosphere and plasmasphere.

  10. The Stratospheric Wind Ingrared Limb Sounder: Investigation of atmospheric dynamics and transport from Eos

    NASA Technical Reports Server (NTRS)

    Mccleese, D. J.

    1992-01-01

    The Stratospheric Wind Infrared Limb Sounder (SWIRLS) is one of the instruments in the atmospheric sounder package to be flown by NASA on the Earth Observing System (EOS) B platform in the late 1990's. SWIRLS is designed to measure the horizontal vector wind field, atmospheric temperature, and the abundances and distributions of ozone and nitrous oxide in the middle atmosphere. These measurements will constitute a dynamical climatology of the stratosphere covering time scales ranging from diurnal to interannual. In addition, the SWIRLS investigation will quantify the physical mechanisms responsible for the structure and variations of stratospheric circulation and temperature fields, including the transport of species, particularly ozone, heat and momentum. Existing data sets lack the combination of accuracy, global and temporal coverage, spatial resoultion and simultaneity required to distinguish unambiguosly between the roles of dynamical and chemical processes in determining the current distribution of ozone and its evolution in the future. The measurement objectives, measurement approach, and instrumentation of SWIRLS is described.

  11. GeoSTAR - A Synthetic Aperture Microwave Sounder for Geostationary Missions

    NASA Technical Reports Server (NTRS)

    Lambrigtsen, Bjorn; Wilson, William; Tanner, Alan; Kangaslahti, Pekka

    2004-01-01

    The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new microwave atmospheric sounder under development. It will bring capabilities similar to those now available on low-earth orbiting environmental satellites to geostationary orbit - where such capabilities have not been available. GeoSTAR will synthesize the multimeter aperture needed to achieve the required spatial resolution, which will overcome the obstacle that has prevented a GEO microwave sounder from being implemented until now. The synthetic aperture approach has until recently not been feasible, due to the high power needed to operate the on-board high-speed massively parallel processing system required for 2D-synthesis, as well as a number of system and calibration obstacles. The development effort under way at JPL, with important contributions from the Goddard Space Flight Center and the University of Michigan, is intended to demonstrate the measurement concept and retire much of the technology risk.

  12. Technology Development for a Hyperspectral Microwave Atmospheric Sounder (HyMAS)

    NASA Technical Reports Server (NTRS)

    Blackwell, W.; Galbraith, C.; Hilliard, L.; Racette, P.; Thompson, E.

    2014-01-01

    The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term hyperspectral microwave is used to indicate an all-weather sounding instrument that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earths atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions.

  13. Underwater Acoustic Transponders Tracking While Mapping With A Multibeam Echo-Sounder

    NASA Astrophysics Data System (ADS)

    de Moustier, C. P.; Franzheim, A.; Testa, W.; Burns, J. M.; Foy, R.

    2010-12-01

    A 160 kHz multibeam echo-sounder was used to interrogate and receive the replies from custom-built miniature underwater acoustic transponders attached to the carapace of king crabs in Womens Bay, Alaska. This new application of multibeam echo-sounders combines acoustic tracking and mapping, thus providing environmental context to the tracking information. Each transponder replies with its own coded sequence that stands out from other echoes received by the sonar. Range and bearing of the replies from multiple transponders can be obtained in a single sonar ping. The king crab experiment was done in 25-35 m of water depth, and the system was successfully tested without animals at 190 m depth. Work supported by NOAA's Undersea Research Program Grant G4768, with field work support from NOAA-NMFS/AFSC/RACE and Electronic Navigation Ltd.

  14. Photoconductive HgCdTe detector assemblies for the GOES imager and sounder instruments

    NASA Astrophysics Data System (ADS)

    Hartley, Jeanne M.; Reine, Marion B.; Terzis, C. L.; Verrilli, Anthony J.; Hassler, Richard A.; Lesondak, Edward P.

    1996-10-01

    The GOES Imager and Sounder instruments each utilize several HgCdTe photoconductive (PC) detectors and detector arrays for detection over the 6.5 to 14.7 micrometers region. These high performance detectors are integrated with germanium aplanat lenses and mounted in miniature hermetically sealed housings. There are demanding requirements on the radiometric performance of these detector assemblies. For LW Sounder detectors, the highest possible sensitivity achievable by a practical HgCdTe photoconductor at the operating temperatures of 100 to 105 K was required. Lockheed Martin designed, fabricated, tested, packaged, qualified, and delivered 7 of the 11 HgCdTe PC detector assemblies for GOES-8, and 9 of the 11 assemblies for GOES- 9. All the n-type HgCdTe starting material was grown at Lockheed Martin.

  15. Theoretical computation of trace gases retrieval random error from measurements of high spectral resolution infrared sounder

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Smith, William L.; Woolf, Harold M.; Theriault, J. M.

    1991-01-01

    The purpose of this paper is to demonstrate the trace gas profiling capabilities of future passive high spectral resolution (1 cm(exp -1) or better) infrared (600 to 2700 cm(exp -1)) satellite tropospheric sounders. These sounders, such as the grating spectrometer, Atmospheric InfRared Sounders (AIRS) (Chahine et al., 1990) and the interferometer, GOES High Resolution Interferometer Sounder (GHIS), (Smith et al., 1991) can provide these unique infrared spectra which enable us to conduct this analysis. In this calculation only the total random retrieval error component is presented. The systematic error components contributed by the forward and inverse model error are not considered (subject of further studies). The total random errors, which are composed of null space error (vertical resolution component error) and measurement error (instrument noise component error), are computed by assuming one wavenumber spectral resolution with wavenumber span from 1100 cm(exp -1) to 2300 cm(exp -1) (the band 600 cm(exp -1) to 1100 cm(exp -1) is not used since there is no major absorption of our three gases here) and measurement noise of 0.25 degree at reference temperature of 260 degree K. Temperature, water vapor, ozone and mixing ratio profiles of nitrous oxide, carbon monoxide and methane are taken from 1976 US Standard Atmosphere conditions (a FASCODE model). Covariance matrices of the gases are 'subjectively' generated by assuming 50 percent standard deviation of gaussian perturbation with respect to their US Standard model profiles. Minimum information and maximum likelihood retrieval solutions are used.

  16. Demonstrating the Operational Value of Atmospheric Infrared Sounder (AIRS) Profiles in the Pre-Convective Environment

    NASA Technical Reports Server (NTRS)

    Kozlowski, Danielle; Zavodsky, Bradley; Stano, Geoffrey; Jedlovec, Gary

    2011-01-01

    The Short-term Prediction Research and Transition (SPoRT) is a project to transition those NASA observations and research capabilities to the weather forecasting community to improve the short-term regional forecasts. This poster reviews the work to demonstrate the value to these forecasts of profiles from the Atmospheric Infrared Sounder (AIRS) instrument on board the Aqua satellite with particular assistance in predicting thunderstorm forecasts by the profiles of the pre-convective environment.

  17. Development of a micro-satellite compatible FTS sounder for sun-occultation measurements

    NASA Astrophysics Data System (ADS)

    Giaccari, Philippe; Moreau, Louis M.; Giroux, Jacques G.; Soucy, Marc-André

    2009-09-01

    The SciSat/ACE mission provided, and still provides, high quality and high spectral resolution measurements of the atmosphere with a FTS sounder in sun-occultation configuration. Based on the comprehensive results and models of SciSat/ACE it is foreseen that most of the desired information can also be retrieved from lower spectral resolution measurements with higher signal-to-noise ratio (SNR) and appropriate data treatment. With the Canadian Space Agency under the Space Technologies Development Program, ABB Analytical developed a small size sun-occultation sounder compatible with a micro-satellite platform that has identical throughput, spectral bandwidth and vertical resolution as ACE. The spectral resolution is decreased by a factor 25 (0.6 cm-1 instead of 0.024 cm-1 for ACE) whereas the SNR performance is highly increased with an equal factor (target of 2500 instead of 100 for ACE over most of the spectral bandwidth between 750 and 4000 cm-1).A prototype of the sun-occultation sounder was built, tested under various thermal conditions and subjected to vibrations similar to those expected at launch. An outdoor experiment was also conducted to test the instrument in sun-occultation conditions. The good behavior of the instrument indicates interesting opportunities for such small footprint sounder on a low-cost micro-satellite mission and potentially good earth coverage if several of such instruments are used in coordination. Depending on the scientific needs, it is possible to adapt the proposed instrument to increase the vertical resolution and/or to extend the measurements on lower altitudes due to the higher SNR performances.

  18. Ionospheric Variability and Storms on Mars

    NASA Technical Reports Server (NTRS)

    Mendillo, Michael

    2004-01-01

    The goal of this grant was to conduct the first-ever study of ionospheric variability on Mars. To do so, we used data from the Radio Science (RS) experiment onboard the Mars Global Surveyor (MGS) satellite. Dr. David Hinson of the RS team at Stanford University was a most helpful and valuable colleague throughout the studies we conducted. For the initial RS datasets available from the MGS mission, there were no severe storms caused by solar wind activity, so we concentrated on day-to-day effects. This turned out to be a wise approach since understanding "normal variability" had to be done before any claim could be made about "space weather" effects. Our approach was three-fold: (1) select a good dataset for characterization of ionosphere variability at Mars, one for which excellent terrestrial data were also available. This turned out to be the period 9-27 March 1999; (2) once the variability at Mars was described, develop and use a new photochemical model of the martian ionosphere to find the extent to which solar variability on those days caused or contributed to the observed patterns; (3) use the results from the above, together with additional datasets from the MGS/RS experiment, to describe some practical consequences that the martian ionosphere would have upon NASA s proposed navigation and communications systems for Mars. The results of these studies showed that: (a) solar variability is the dominant source of ionospheric variability at Mars (during periods of quiet solar wind), (b) that current models do a good job in portraying such effects at the height of the ionospheric peak electron density, and (c) that ionospheric structure on Mars can affect attempts at precise position-fixing at Mars should relatively high (GPS-like) frequencies not be used in a Mars communications and navigation system.

  19. Ionospheric Impacts on UHF Space Surveillance

    NASA Astrophysics Data System (ADS)

    Jones, J.; Ceron-Gomez, D.; Richards, G.

    2016-09-01

    Earth's atmosphere contains regions of ionized plasma caused by the interaction of highly energetic solar radiation. This region of ionization is called the ionosphere and varies significantly with altitude, latitude, local solar time, season, and solar cycle. Significant ionization begins at about 100 km (E layer) with a peak in the ionization at about 350 km (F2 layer). Above the F2 layer, the atmosphere is mostly ionized but the ion and electron densities are low due to the unavailability of neutral molecules for ionization so the electron density decreases exponentially with height to well over 1000 km. The gradients of these variations in the ionosphere play a significant role in radio wave propagation. These gradients induce variations in the index of refraction and cause some radio waves to refract. The amount of refraction depends on the magnitude and direction of the electron density gradient and the frequency of the radio wave. The refraction is significant at HF frequencies (3-30 MHz) with decreasing effects toward the UHF (300-3000 MHz) range. UHF is commonly used for tracking of space objects in low Earth orbit (LEO). While ionospheric refraction is small for UHF frequencies, it can cause errors in range, azimuth angle, and elevation angle estimation by ground-based radars tracking space objects. These errors can cause significant uncertainty in precise orbit determinations. For radio waves transiting the ionosphere, it is important to understand and account for these effects. Using a sophisticated radio wave propagation tool suite and an empirical ionospheric model, we calculate the errors induced by the ionosphere in a simulation of a notional space surveillance radar tracking objects in LEO. These errors are analyzed to determine correlations with ionospheric variability. Corrections to surveillance radar measurements can be adapted from our simulation capability.

  20. On the remote sensing of cloud properties from satellite infrared sounder data

    NASA Technical Reports Server (NTRS)

    Yeh, H. Y. M.

    1984-01-01

    A method for remote sensing of cloud parameters by using infrared sounder data has been developed on the basis of the parameterized infrared transfer equation applicable to cloudy atmospheres. The method is utilized for the retrieval of the cloud height, amount, and emissivity in 11 micro m region. Numerical analyses and retrieval experiments have been carried out by utilizing the synthetic sounder data for the theoretical study. The sensitivity of the numerical procedures to the measurement and instrument errors are also examined. The retrieved results are physically discussed and numerically compared with the model atmospheres. Comparisons reveal that the recovered cloud parameters agree reasonably well with the pre-assumed values. However, for cases when relatively thin clouds and/or small cloud fractional cover within a field of view are present, the recovered cloud parameters show considerable fluctuations. Experiments on the proposed algorithm are carried out utilizing High Resolution Infrared Sounder (HIRS/2) data of NOAA 6 and TIROS-N. Results of experiments show reasonably good comparisons with the surface reports and GOES satellite images.

  1. Wide Field Collimator 2 (WFC2) for GOES Imager and Sounder

    NASA Technical Reports Server (NTRS)

    Etemad, Shahriar; Bremer, James C.; Zukowski, Barbara J.; Pasquale, Bert A.; zukowski, Tmitri J.; Prince, Robert E.; O'Neill, Patrick A.; Ross, Robert W.

    2004-01-01

    Two of the GOES instruments, the Imager and the Sounder, perform scans of the Earth to provide a full disc picture of the Earth. To verify the entire scan process, an image of a target that covers an 18 deg. circular field-of-view is collimated and projected into the field of regard of each instrument. The Wide Field Collimator 2 (WFC2) has many advantages over its predecessor, WFC1, including lower thermal dissipation higher fir field MTF, smaller package, and a more intuitive (faster) focusing process. The illumination source is an LED array that emits in a narrow spectral band centered at 689 nm, within the visible spectral bands of the Imager and Sounder. The illumination level can be continuously adjusted electronically. Lower thermal dissipation eliminates the need for forced convection cooling and minimizes time to reach thermal stability. The lens system has been optimized for the illumination source spectral output and athernalized to remain in focus during bulk temperature changes within the laboratory environment. The MTF of the lens is higher than that of the WFC1 at the edge of FOV. The target is focused in three orthogonal motions, controlled by an ergonomic system that saves substantial time and produces a sharper focus. Key words: Collimator, GOES, Imager, Sounder, Projector

  2. A Fast Radiative Transfer Model for the Meteor- M satellite-based hyperspectral IR sounders

    NASA Astrophysics Data System (ADS)

    Uspensky, A. B.; Rublev, A. N.; Rusin, E. V.; Pyatkin, V. P.

    2014-12-01

    The methodological and computational aspects of Fast Radiative Transfer Model (FRTM) development designed for the analysis and validation of the data of measurements using satellite-based instrument-hyperspectral IR sounders of high spectral resolution—are considered. A description of the FRTM is given for the analysis and modeling of the measurements by the IRFS-2 IR Fourier spectrometer for polarorbiting meteorological satellites of the Meteor-M series based on the known RTTOV FRTM. Computational efficiency is estimated and the results of the verification of developed FRTM are presented. They were obtained from a comparison of model simulations with exact line-by-line calculations for the IRFS-2 IR sounder. The increase in computational performance and the accuracy of the FRTM, caused by the application of the algorithms of the principal components method, are discussed. The construction of radiative models, which use the algorithm of the Monte Carlo method and are applicable for the analysis and modeling of the data of IR sounders under conditions of cloudiness in the instrument field of view, is considered.

  3. Inter-Comparison of GOES-8 Imager and Sounder Skin Temperature Retrievals

    NASA Technical Reports Server (NTRS)

    Haines, Stephanie L.; Suggs, Ronnie J.; Jedlovec, Gary J.; Arnold, James E. (Technical Monitor)

    2001-01-01

    Skin temperature (ST) retrievals derived from geostationary satellite observations have both high temporal and spatial resolutions and are therefore useful for applications such as assimilation into mesoscale forecast models, nowcasting, and diagnostic studies. Our retrieval method uses a Physical Split Window technique requiring at least two channels within the longwave infrared window. On current GOES satellites, including GOES-11, there are two Imager channels within the required spectral interval. However, beginning with the GOES-M satellite the 12-um channel will be removed, leaving only one longwave channel. The Sounder instrument will continue to have three channels within the longwave window, and therefore ST retrievals will be derived from Sounder measurements. This research compares retrievals from the two instruments and evaluates the effects of the spatial resolution and sensor calibration differences on the retrievals. Both Imager and Sounder retrievals are compared to ground-truth data to evaluate the overall accuracy of the technique. An analysis of GOES-8 and GOES-11 intercomparisons is also presented.

  4. Understanding intersatellite biases of microwave humidity sounders using global simultaneous nadir overpasses

    NASA Astrophysics Data System (ADS)

    John, Viju O.; Holl, Gerrit; Buehler, Stefan A.; Candy, Brett; Saunders, Roger W.; Parker, David E.

    2012-01-01

    Simultaneous nadir overpasses (SNOs) of polar-orbiting satellites are most frequent in polar areas but can occur at any latitude when the equatorial crossing times of the satellites become close owing to orbital drift. We use global SNOs of polar orbiting satellites to evaluate the intercalibration of microwave humidity sounders from the more frequent high-latitude SNOs. We have found based on sensitivity analyses that optimal distance and time thresholds for defining collocations are pixel centers less than 5 km apart and time differences less than 300 s. These stringent collocation criteria reduce the impact of highly variable surface or atmospheric conditions on the estimated biases. Uncertainties in the estimated biases are dominated by the combined radiometric noise of the instrument pair. The effects of frequency changes between different versions of the humidity sounders depend on the amount of water vapor in the atmosphere. There are significant scene radiance and thus latitude dependencies in the estimated biases and this has to taken into account while intercalibrating microwave humidity sounders. Therefore the results obtained using polar SNOs will not be representative for moist regions, necessitating the use of global collocations for reliable intercalibration.

  5. Ionospheric response over Europe during the solar eclipse of March 20, 2015

    NASA Astrophysics Data System (ADS)

    Hoque, Mohammed Mainul; Wenzel, Daniela; Jakowski, Norbert; Gerzen, Tatjana; Berdermann, Jens; Wilken, Volker; Kriegel, Martin; Sato, Hiroatsu; Borries, Claudia; Minkwitz, David

    2016-10-01

    function. By modelling TEC depletion and knowing the Sun's obscuration function in advance, Global Navigation Satellite System (GNSS) operators may improve the broadcast ionospheric correction during a solar eclipse day.

  6. Modeling the global positioning system signal propagation through the ionosphere

    NASA Technical Reports Server (NTRS)

    Bassiri, S.; Hajj, G. A.

    1992-01-01

    Based on realistic modeling of the electron density of the ionosphere and using a dipole moment approximation for the Earth's magnetic field, one is able to estimate the effect of the ionosphere on the Global Positioning System (GPS) signal for a ground user. The lowest order effect, which is on the order of 0.1-100 m of group delay, is subtracted out by forming a linear combination of the dual frequencies of the GPS signal. One is left with second- and third-order effects that are estimated typically to be approximately 0-2 cm and approximately 0-2 mm at zenith, respectively, depending on the geographical location, the time of day, the time of year, the solar cycle, and the relative geometry of the magnetic field and the line of sight. Given the total electron content along a line of sight, the authors derive an approximation to the second-order term which is accurate to approximately 90 percent within the magnetic dipole moment model; this approximation can be used to reduce the second-order term to the millimeter level, thus potentially improving precise positioning in space and on the ground. The induced group delay, or phase advance, due to second- and third-order effects is examined for two ground receivers located at equatorial and mid-latitude regions tracking several GPS satellites.

  7. Experimental evidence of electromagnetic pollution of ionosphere

    NASA Astrophysics Data System (ADS)

    Pronenko, Vira; Korepanov, Valery; Dudkin, Denis

    The Earth’s ionosphere responds to external perturbations originated mainly in the Sun, which is the primary driver of the space weather (SW). But solar activity influences on the ionosphere and the Earth's atmosphere (i.e., the energy transfer in the direction of the Sun-magnetosphere-ionosphere-atmosphere-surface of the Earth), though important, is not a unique factor affecting its state - there is also a significant impact of the powerful natural and anthropogenic processes, which occur on the Earth’s surface and propagating in opposite direction along the Earth’s surface-atmosphere-ionosphere-magnetosphere chain. Numerous experimental data confirm that the powerful sources and consumers of electrical energy (radio transmitters, power plants, power lines and industrial objects) cause different ionospheric phenomena, for example, changes of the electromagnetic (EM) field and plasma in the ionosphere, and affect on the state of the Earth atmosphere. Anthropogenic EM effects in the ionosphere are already observed by the scientific satellites and the consequences of their impact on the ionosphere are not currently known. Therefore, it is very important and urgent task to conduct the statistically significant research of the ionospheric parameters variations due to the influence of the powerful man-made factors, primarily owing to substantial increase of the EM energy production. Naturally, the satellite monitoring of the ionosphere and magnetosphere in the frequency range from tens of hertz to tens of MHz with wide ground support offers the best opportunity to observe the EM energy release, both in the global and local scales. Parasitic EM radiation from the power supply lines, when entering the ionosphere-magnetosphere system, might have an impact on the electron population in the radiation belt. Its interaction with trapped particles will change their energy and pitch angles; as a result particle precipitations might occur. Observations of EM emission by

  8. Ionospheric calibration for single frequency altimeter measurements

    NASA Technical Reports Server (NTRS)

    Schreiner, William S.; Born, George H.; Markin, Robert E.

    1994-01-01

    This study is a preliminary analysis of the effectiveness (in terms of altimeter calibration accuracy) of various ionosphere models and the Global Positioning System (GPS) to calibrate single frequency altimeter height measurements for ionospheric path delay. In particular, the research focused on ingesting GPS Total Electron Content (TEC) data into the physical Parameterized Real-Time Ionospheric Specification Model (PRISM), which estimates the composition of the ionosphere using independent empirical and physical models and has the capability of adjusting to additional ionospheric measurements. Two types of GPS data were used to adjust the PRISM model: GPS receiver station data mapped from line-of-sight observations to the vertical at the point of interest and a grid map (generated at the Jet Propulsion Laboratory) of GPS derived TEC in a sun-fixed longitude frame. The adjusted PRISM TEC values, as well as predictions by the International Reference Ionosphere (IRI-90), a climatological (monthly mean) model of the ionosphere, were compared to TOPEX dual-frequency TEC measurements (considered as truth) for a number of TOPEX sub-satellite tracks. For a 13.6 GHz altimeter, a Total Electron Content (TEC) of 1 TECU 10(exp 16) electrons/sq m corresponds to approximately 0.218 centimeters of range delay. A maximum expected TEC (at solar maximum or during solar storms) of 10(exp 18) electrons/sq m will create 22 centimeters of range delay. Compared with the TOPEX data, the PRISM predictions were generally accurate within the TECU when the sub-satellite track of interest passed within 300 to 400 km of the GPS TEC data or when the track passed through a night-time ionosphere. If neither was the case, in particular if the track passed through a local noon ionosphere, the PRISM values differed by more than 10 TECU and by as much as 40 TECU. The IRI-90 model, with no current ability to unseat GPS data, predicted TEC to a slightly higher error of 12 TECU. The performance of

  9. Mesoscale ionospheric tomography at the Auroral region

    NASA Astrophysics Data System (ADS)

    Luntama, J.; Kokkatil, G. V.

    2008-12-01

    FMI (Finnish Meteorological Institute) has used observations from the dense GNSS network in Finland for high resolution regional ionospheric tomography. The observation system used in this work is the VRS (Virtual Reference Station) network in Finland operated by Geotrim Ltd. This network contains 86 GNSS ground stations providing two frequency GPS and GLONASS observations with the sampling rate of 1 Hz. The network covers the whole Finland and the sampling of the ionosphere is very good for observing mesoscale ionospheric structures at the Auroral region. The ionospheric tomography software used by FMI is the MIDAS (Multi-Instrument Data Analysis System) algorithm developed and implemented by the University of Bath (Mitchell and Spencer, 2003). MIDAS is a 3-D extension of the 2-D tomography algorithm originally presented by Fremouw et al. (1992). The research at FMI is based on ground based GNSS data collected in December 2006. The impacts of the two geomagnetic storms during the month are clearly visible in the retrieved electron density and TEC maps and they can be correlated with the magnetic field disturbances measured by the IMAGE magnetometer network. This is the first time that mesoscale structures in the ionospheric plasma can be detected from ground based GNSS observations at the Auroral region. The continuous high rate observation data from the Geotrim network allows monitoring of the temporal evolution of these structures throughout the storms. Validation of the high resolution electron density and TEC maps is a challenge as independent reference observations with a similar resolution are not available. FMI has compared the 3-D electron density maps against the 2-D electron density plots retrieved from the observations from the Ionospheric Tomography Chain operated by the Sodankylä Geophysical Observatory (SGO). Additional validation has been performed with intercomparisons with observations from the ground based magnetometer and auroral camera network

  10. The Jovian ionospheric E region

    NASA Astrophysics Data System (ADS)

    Kim, Y. H.; Fox, J. L.

    1991-02-01

    A model of the Jovian ionosphere was constructed, that includes direct photoionization of hydrocarbon molecules. A high-resolution solar spectrum was synthesized from Hinteregger's solar maximum spectrum (F79050N), and high-resolution cross sections for photoabsorption by H2 bands in the range 842 to 1116 A were constructed. Two strong solar lines and about 30 percent of the continuum flux between 912 and 1116 A penetrate below the methane homopause despite strong absorption by CH4 and H2. It is found that hydrocarbons (mainly C2H2 are ionized at a maximum rate of 55/cu cm per sec at 320 km above the ammonia cloud tops. The hydrocarbon ions produced are quickly converted to more complex hydrocarbon ions through reactions with CH4, C2H2, C2H6, and C2H4. It is found that a hydrocarbon ion layer is formed near 320 km that is about 50 km wide with a peak density in excess of 10,000/cu cm.

  11. Electric fields in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.

    1975-01-01

    F-region drift velocities, measured by incoherent-scatter radar were analyzed in terms of diurnal, seasonal, magnetic activity, and solar cycle effects. A comprehensive electric field model was developed that includes the effects of the E and F-region dynamos, magnetospheric sources, and ionospheric conductivities, for both the local and conjugate regions. The E-region dynamo dominates during the day but at night the F-region and convection are more important. This model provides much better agreement with observations of the F-region drifts than previous models. Results indicate that larger magnitudes occur at night, and that daily variation is dominated by the diurnal mode. Seasonal variations in conductivities and thermospheric winds indicate a reversal in direction in the early morning during winter from south to northward. On magnetic perturbed days and the drifts deviate rather strongly from the quiet days average, especially around 13 L.T. for the northward and 18 L.T. for the westward component.

  12. Meteoric Ions in Planetary Ionospheres

    NASA Technical Reports Server (NTRS)

    Pesnell, W. D.; Grebowsky, Joseph M.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Solar system debris, in the form of meteoroids, impacts every planet. The flux, relative composition and speed of the debris at each planet depends on the planet's size and location in the solar system. Ablation in the atmosphere evaporates the meteoric material and leaves behind metal atoms. During the ablation process metallic ions are formed by impact ionization. For small inner solar system planets, including Earth, this source of ionization is typically small compared to either photoionization or charge exchange with ambient molecular ions. For Earth, the atmosphere above the main deposition region absorbs the spectral lines capable of ionizing the major metallic atoms (Fe and Mg) so that charge exchange with ambient ions is the dominant source. Within the carbon dioxide atmosphere of Mars (and possibly Venus), photoionization is important in determining the ion density. For a heavy planet like Jupiter, far from the sun, impact ionization of ablated neutral atoms by impacts with molecules becomes a prominent source of ionization due to the gravitational acceleration to high incident speeds. We will describe the processes and location and extent of metal ion layers for Mars, Earth and Jupiter, concentrating on flagging the uncertainties in the models at the present time. This is an important problem, because low altitude ionosphere layers for the planets, particularly at night, probably consist predominantly of metallic ions. Comparisons with Earth will be used to illustrate the differing processes in the three planetary atmospheres.

  13. Ionospheric disturbances and gravity waves

    NASA Technical Reports Server (NTRS)

    Eun, H.; Gross, S. H.

    1976-01-01

    The response of ionization to a gravity wave moving through the ionosphere is studied. Hydrodynamic equations are used, and local thermodynamic equilibrium is imposed for simplicity. The treatment involves a perturbation analysis, and the background medium is assumed to be time stationary, horizontally stratified, and known. It is shown that ionization may be locally resonant at each level for certain frequencies and directions, for which condition neutral and ionized particles are considered closely or critically coupled. The phase direction for this critical coupling is always downward in the absence of a magnetic field. A magnetic field results in two resonant directions for the same frequency, and these directions are mostly downward. Observed TID's associated with gravity waves may be indicative of such resonances. It is also noted that strong coupling may occur to neutral acoustic waves at high altitudes. Previous investigations restrict their use of momentum equations to the diffusion equation. The analysis also shows that such restrictions result in the neglect of terms arising from momentum transport due to any background ambipolar diffusion velocity and wave motion. These terms are mostly relevant at higher altitudes.

  14. Atmospheric River Observations with the HAMSR Aircraft Microwave Sounder

    NASA Astrophysics Data System (ADS)

    Lambrigtsen, B.; Brown, S. T.; Schreier, M. M.; Dang, H. V. T.; Behrangi, A.

    2015-12-01

    The High Altitude MMIC Sounding Radiometer (HAMSR) was developed at the Jet Propulsion Laboratory in 2001 to serve as an aircraft based hurricane observatory. It initially flew on the high altitude ER-2 and later on the DC-8. More recently it was modified to fly on the Global Hawk UAV. It uses the most advanced technology and is among the most sensitive instruments of its kind. In addition to a number of NASA hurricane field campaigns - mostly in the North Atlantic, HAMSR has participated in two atmospheric river campaigns off the California coast, one in 2011 (WISPAR) and one in 2015 (CalWater2). We will discuss observations from the 2015 campaign, with particular focus on a flight over an atmsospheric river making landfall in central California in early February, as well as compare with highlights from the 2011 flights. Copyright 2015 California Institute of Technology. Government sponsorship acknowledged.

  15. Characteristics of High Latitude Ionosphere Scintillations

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2012-12-01

    As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

  16. Fast ionospheric feedback instability and substorm onset

    NASA Technical Reports Server (NTRS)

    Lysak, Robert L.; Grieger, John; Song, Yan

    1992-01-01

    A study suggesting that the Alfven resonator can play an important role in modifying the ionosphere on the time and space scales required to play a significant role in substorm formation is presented. Although the effect of magnetosphere-ionosphere coupling on the onset of substorms has been studied, the effects due to gradients of the Alfven speed along auroral field line were neglected. The large increase of the Alfven speed with altitude above the ionosphere creates an effective resonant cavity, which can lead to fluctuations in the electric and magnetic fields as well as in particle fluxes in the range 0.1 to 1 Hz. Such fluctuations can be observed from the ground as PiB pulsations associated with substorm onset. These fluctuations can be excited by a fast feedback instability, which can grow on time scales much less than the Alfven travel time between the ionosphere and the plasma sheet. The instability enhances the value of both the Pedersen and Hall conductivity, and may play a role in preparing the ionosphere for substorm onset.

  17. Geophysicochemical model of an ionospheric auroral gyroscope

    NASA Astrophysics Data System (ADS)

    Serban, Andreea I.; Geicu, Ovidiu I.; Serban, Florea

    2016-01-01

    This study presents a geophysicochemical model of an ionospheric auroral gyroscope. The gyroscopic effect occurs due to the electromagnetic interaction in Earth's polar regions between two types of vertical cavity auroras: the herpolhodic cone (proton cavity aurora), operating in the cusp polar region, and two polhodic cones (an electronic cone and a protonic cone), operating in the aurora region. The ratio between the angular speeds of the herpolhodic and polhodic cones is established by the angle between Earth's rotational axis and the geomagnetic dipole axis. We have developed a theory of the ionospheric auroral gyroscope as a kinematic part of the terrestrial magnetosphere and ionosphere that enables a unified explanation of important macroscopic phenomena that occur at this level. Accordingly, we have explained the oval shape of the polar auroras, Schumann resonances, geomagnetic micropulsation excitation, and the structuring of Earth's areas of radiation. The terrestrial gravitomagnetic field and dark matter are implicated in the initiation and behavior of the auroral ionospheric gyroscope, both of which provide stability and accuracy. Viewed in a wider context, the ionospheric auroral gyroscope theory could offer a way to experimentally investigate dark matter on Earth. Furthermore, it may have a potential value as a predictive tool, providing information about the large earthquakes and Earth's phenomena.

  18. Ionospheric TEC observations from TOPEX satellite

    SciTech Connect

    Vladimer, J.A.; Ewell, V.R.; Lee, M.C.; Doherty, P.H.; Decker, D.T.; Anderson, D.N.; Klobuchar, J.A.

    1996-12-31

    Variability of Total Electron Content (TEC) in the equatorial anomaly region of the ionosphere can be studied extensively using the results of measurements taken by the NASA/CNES satellite, TOPEX/Poseidon. The NASA radar altimeter (NRA) is the first space-borne dual-frequency altimeter capable of accurately measuring vertical ionospheric TEC below 1,340 km. TOPEX TEC observations have already been used to support results from an ionospheric measurement campaign that was conducted in equatorial anomaly regions of South America by Phillips Laboratory in Spring, 1994. The best agreement in TEC values is seen during intervals of longitudinal proximity of the satellites` paths. The TOPEX over-ocean data can be used as a supplement to land based measurements in applications to ionospheric research at low and middle latitudes. This study focuses on comparisons between TOPEX vertical TEC data and GPS equivalent vertical TEC measurements taken near the East and West coastal regions of South America. Also the Phillips Laboratory Global Parameterized Ionospheric Model (PIM) is utilized in an effort to estimate slant to vertical conversion errors.

  19. Estimating Ionosphere Conductance on Global Spatial Scales

    NASA Astrophysics Data System (ADS)

    Waters, C. L.; Anderson, B. J.; Green, D. L.; Korth, H.

    2014-12-01

    The ionosphere represents the Earthward boundary of space. For large scale processes, the height integrated conductivities (conductances) of the ionosphere are known to modulate the energy transfer between the magnetosphere and ionosphere. Estimating the Pedersen and Hall conductances on a global scale, particularly in the auroral regions, is fundamental to understanding the dynamics of the high latitude ionosphere and thermosphere. Experimental measurements with sufficient spatial coverage and with time scales of order of minutes or less are required. While the spatial coverage of HF radar and spacecraft measurements has recently improved, it turns out that the most challenging aspects for global estimates of ionosphere conductance are directly related to ground-based magnetometer data. The Iridium satellite constellation consists of more than 70 satellites in circular, polar, 780 km altitude orbits which provides a unique opportunity to obtain in-situ measurements of the global distribution of the Birkeland currents and associated magnetic field perturbations. In this paper, examples and challenges for combining the Iridium satellite, HF radar and ground magnetometer data in order to produce estimates of the Pedersen and Hall conductances on global spatial scales will be presented. We discuss limiting factors in the methodology and some possible alternatives.

  20. A Comparative Study of the Ionospheric TEC Measurements Using Global Ionospheric Maps of GPS, TOPEX Radar and the Bent Model

    NASA Technical Reports Server (NTRS)

    Ho, C.; Wilson, B.; Mannucci, A.; Lindqwister, U.; Yuan, D.

    1997-01-01

    Global ionospheric mapping (GIM) is a new, emerging technique for determining global ionospheric TEC (total electron content) based on measurements from a worldwide network of Global Positioning System (GPS) receivers.

  1. Cloud properties and bulk microphysical properties of semi-transparent cirrus from IR Sounders

    NASA Astrophysics Data System (ADS)

    Stubenrauch, Claudia; Feofilov, Artem; Armante, Raymond; Guignard, Anthony

    2013-04-01

    Satellite observations provide a continuous survey of the atmosphere over the whole globe. IR sounders have been observing our planet since 1979. The spectral resolution has improved from TIROS-N Operational Vertical Sounders (TOVS) to the Atmospheric InfraRed Sounder (AIRS), and to the InfraRed Atmospheric Sounding Interferometer (IASI); resolution within the CO2 absorption band makes these passive sounders most sensitive to semi-transparent cirrus (about 30% of all clouds), day and night. The LMD cloud property retrieval method developed for TOVS, has been adapted to the second generation of IR sounders like AIRS and, recently, IASI. It is based on a weighted χ2 method using different channels within the 15 micron CO2 absorption band. Once the cloud physical properties (cloud pressure and IR emissivity) are retrieved, cirrus bulk microphysical properties (De and IWP) are determined from spectral emissivity differences between 8 and 12 μm. The emissivities are determined using the retrieved cloud pressure and are then compared to those simulated by the radiative transfer model. For IASI, we use the latest version of the radiative transfer model 4A (http://4aop.noveltis.com), which has been coupled with the DISORT algorithm to take into account multiple scattering of ice crystals. The code incorporates single scattering properties of column-like or aggregate-like ice crystals provided by MetOffice (Baran et al. (2001); Baran and Francis (2004)). The synergy of AIRS and two active instruments of the A-Train (lidar and radar of the CALIPSO and CloudSat missions), which provide accurate information on vertical cloud structure, allowed the evaluation of cloud properties retrieved by the weighted χ2 method. We present first results for cloud properties obtained with IASI/ Metop-A and compare them with those of AIRS and other cloud climatologies having participated in the GEWEX cloud assessment. The combination of IASI observations at 9:30 AM and 9:30 PM complement

  2. An Antarctica-to-Spain HF ionospheric radio link: Sounding results

    NASA Astrophysics Data System (ADS)

    Vilella, C.; Miralles, D.; Pijoan, J. L.

    2008-08-01

    Our research group in Electromagnetism and Communications is involved in a project dealing with the channel characterization of an ionospheric radio link from the Spanish Antarctic Base (62.6°S, 60.4°W) to the Observatori de l'Ebre (40.8°N, 0.5°E) in Spain. Since the link was established for the first time on December 2003, the sounder and measurement techniques have been improved on the basis of the preliminary results. In this paper, the final results of the project corresponding to the 2006/2007 sounding survey are presented. First the hardware and measurement techniques used to probe the channel are described. Then the results in terms of channel availability (and its daily, hourly, and frequency variation), multipath and Doppler spreads, and signal-to-noise ratio are discussed. These results are being used to design the physical layer of a low data rate transmission system intended to send the information acquired by a geomagnetic sensor in the Antarctica.

  3. Investigation of the Accuracy of Ionospheric Models at Mid-Latitudes: Examining Ionospheric Metrics

    NASA Astrophysics Data System (ADS)

    Eccles, V.; Sojka, J. J.; Gonzalez, S.; Fuller-Rowell, T. J.; Howsden, M.

    2004-12-01

    The electron density specification of the ionosphere is the key parameter supporting many operational products. To assess the accuracy of tools based on space weather models of the ionosphere one must know the accuracy of the underlining models. We are developing a software/database package to assess the accuracy of ionospheric models. The package will be placed at the Community Coordinated Modeling Center (CCMC). Initial focus is on the mid-latitude ionosphere as observed by the Arecibo Incoherent Scatter Radar (ISR). This ISR database has extensive ionospheric coverage over variability in solar cycle, season, local time, and geomagnetic activity. The assessments of models need to be based on careful constructed metric definitions to compare the model specifications with the ISR "ground truth." Our goals for the assessment tool are (1) to provide reliable, metric assessment of models for users represented by agencies of the Nation Space Weather Program and, (2) to provide the scientific community with an assessment of conditions when models are adequate and inadequate. The second implementation plan of the NSWP (2000) has established the priority of metrics and has specified these metrics. We begin with the NSWP ionospheric metrics as a reasonable starting place, but examine other strategies to assess ionosphere weather specifications through several new metric definitions for the F region. We present our initial studies on the weaknesses and benefits of several different metric definitions for F region profile accuracy. Three models will be use in the metric assessment (1) the physics-based Ionospheric Forecast Model (IFM), (2) the physics-based and Coupled Thermospheric-Ionospheric-Plasmasphere-electrodynamics Model (CTIPe), and (3) the empirical International Reference Model (IRI). Central to creating reliable metric results is the need to quantify the quality and accuracy of the "ground truth" ISR database. Metric issues associated with ISR operational modes

  4. Excitation of Earth-Ionosphere Waveguide in the ELF and Lower VLF Bands by Modulated Ionospheric Current

    DTIC Science & Technology

    1993-05-21

    orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the...for HAARP there might be marginal value in modulating at altitudes as high as 100 km. 14. SUBJECT TERMS ionospheric modification ionospheric currents...34 ionospheric heating 16. PRICE CODE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF OF REPORT

  5. An Initial Investigation of Ionospheric Gradients for Detection of Ionospheric Disturbances over Turkey

    NASA Astrophysics Data System (ADS)

    Koroglu, Meltem; Arikan, Feza; Koroglu, Ozan

    2015-04-01

    Ionosphere is an ionized layer of earth's atmosphere which affect the propagation of radio signals due to highly varying electron density structure. Total Electron Content (TEC) and Slant Total Electron Content (STEC) are convenient measures of total electron density along a ray path. STEC model is given by the line integral of the electron density between the receiver and GPS satellite. TEC and STEC can be estimated by observing the difference between the two GPS signal time delays that have different frequencies L1 (1575 MHz) and L2 (1227 MHz). During extreme ionospheric storms ionospheric gradients becomes larger than those of quiet days since time delays of the radio signals becomes anomalous. Ionosphere gradients can be modeled as a linear semi-infinite wave front with constant propagation speed. One way of computing the ionospheric gradients is to compare the STEC values estimated between two neighbouring GPS stations. In this so-called station-pair method, ionospheric gradients are defined by dividing the difference of the time delays of two receivers, that see the same satellite at the same time period. In this study, ionospheric gradients over Turkey are computed using the Turkish National Permanent GPS Network (TNPGN-Active) between May 2009 and September 2012. The GPS receivers are paired in east-west and north-south directions with distances less than 150 km. GPS-STEC for each station are calculated using IONOLAB-TEC and IONOLAB-BIAS softwares (www.ionolab.org). Ionospheric delays are calculated for each paired station for both L1 and L2 frequencies and for each satellite in view with 30 s time resolution. During the investigation period, different types of geomagnetic storms, Travelling Ionospheric Disturbances (TID), Sudden Ionospheric Disturbances (SID) and various earthquakes with magnitudes between 3 to 7.4 have occured. Significant variations in the structure of station-pair gradients have been observed depending on location of station-pairs, the

  6. Ionospheric Cubeswarm Concept Study: using low-resource instrumentation for truly multipoint in situ ionospheric observations

    NASA Astrophysics Data System (ADS)

    Hampton, D.; Lynch, K. A.; Earle, G. D.; Mannucci, A. J.; Clayton, R.; Fisher, L. E.; Fernandes, P. A.; Roberts, M.; Zettergren, M. D.

    2015-12-01

    Magnetosphere-ionosphere coupling currents close in the nightside lower ionosphere. These spatially inhomogeneous and time varying volume currents are difficult to capture with in situ observations. Our understanding of M-I coupling systems is limited by our understanding of the actual structure of ionospheric current closure. A path forward includes assimilation of a variety of data sets into increasingly capable ionospheric models. While each data set provides only a piece of the picture, the assimilation process allows optimal use of each piece.An important development for the necessary in situ observations involves making them truly multi-point, and therefore, low-resource. For thermal particle observations, the high densities of the lower ionosphere allow the use of low-gain (current-sensing rather than particle-counting) particle sensors. One observational goal is the definition of the actual structure of ionospheric closure currents. This can be approached with a number of different measurement techniques, in tandem with an ionospheric model, since the closure currents need to follow the rules of electrodynamics and current continuity. Low resource thermal plasma sensors such as retarding potential analyzers and drift meters can provide valuable measurements of plasma parameters, including density and plasma flow, without the need for high voltages or deployable boom systems. These low-resource measurements, which can be reproduced on arrays of in situ observation platforms, used in tandem with proper plasma physics interpretation of their signatures in the disturbed observing environment, and as part of an assimilated data set into an ionospheric model, can allow us to progress in our understanding of ionospheric structuring and its effects on auroral coupling. Now, with increasingly capable multipoint arrays of spacecraft, and quantitative 2D-with-time context from cameras and imagery, we are moving toward truly multipoint studies of the system

  7. Ionosphere/microwave beam interaction study

    NASA Technical Reports Server (NTRS)

    Gordon, W. E.; Duncan, L. M.

    1978-01-01

    The microwave beam of the Solar Power Satellite (SPS) is predicted to interact with the ionosphere producing thermal runaway up to an altitude of about 100 kilometers at a power density threshold of 12 mW/cm sq (within a factor of two). The operation of the SPS at two frequencies, 2450 and 5800 MHz, is compared. The ionosphere interaction is less at the higher frequency, but the tropospheric problem scattering from heavy rain and hail is worse at the higher frequency. Microwave signals from communication satellites were observed to scintillate, but there is some concern that the uplink pilot signal may be distorted by the SPS heated ionosphere. The microwave scintillations are only observed in the tropics in the early evenings near the equinoxes. Results indicate that large phase errors in the uplink pilot signal can be reduced.

  8. Beacon satellite receiver for ionospheric tomography

    NASA Astrophysics Data System (ADS)

    Vierinen, J.; Norberg, J.; Lehtinen, M. S.; Amm, O.; Roininen, L.; Väänänen, A.; Erickson, P. J.; McKay-Bukowski, D.

    2014-12-01

    We introduce a new coherent dual-channel beacon satellite receiver intended for ionospheric tomography. The measurement equation includes neutral atmosphere and ionosphere propagation effects, relative errors in satellite and receiver clocks, and residual Doppler shifts caused by errors in the satellite ephemeris. We also investigate the distribution of errors for phase curve measurements and the use of phase curve measurements for limited angle tomography using the framework of statistical linear inverse problems. We describe the design of our beacon satellite receiver software and present one possible hardware configuration. Finally, we present results obtained using a network of four newly developed receivers and compare the results with those of an existing ionospheric tomography network at Sodankylä Geophysical Observatory.

  9. Whistlers. [in earth ionosphere and magnetosphere

    NASA Technical Reports Server (NTRS)

    Park, C. G.

    1982-01-01

    Theoretical models of ionospheric whistler phenomena are reviewed and compared with experimental data. Whistlers were characterized as lightning discharges through a dispersive medium in 1919, with the first observed appearance of whistler noises detected in telephone communications. Magneto-ionic theory is used to characterize whistlers, with the Appleton-Hartree equations applied to the wave fields arising from lightning interactions with ionospheric plasma. Large values of the refractive index or slow propagation speeds give rise to the whistler mode, i.e., propagation of the wave through plasmas of any density. Propagation through the ionosphere is examined with the Snell's law, and account is taken of absorption and the necessity of obtaining full-wave solutions. Finally, theories are under development to explain the occurrence of ducting, i.e., guiding of the whistler wave by field-aligned plasma density irregularities.

  10. Rocket studies of the lower ionosphere

    NASA Technical Reports Server (NTRS)

    Bowhill, Sidney A.

    1990-01-01

    The earth's ionosphere in the altitude range of 50 to 200 km was investigated by rocket-borne sensors, supplemented by ground-based measurement. The rocket payloads included mass spectrometers, energetic particle detectors, Langmuir probes and radio propagation experiments. Where possible, rocket flights were included in studies of specific phenomena, and the availability of data from other experiments greatly increased the significance of the results. The principal ionospheric phenomena studied were: winter anomaly in radiowave absorption, ozone and molecular oxygen densities, mid-latitude sporadic-E layers, energetic particle precipitation at middle and low latitudes, ionospheric instabilities and turbulence, and solar eclipse effects in the D and E regions. This document lists personnel who worked on the project, and provides a bibliography of resultant publications.

  11. Ionospheric density enhancement during relativistic electron precipitation

    NASA Technical Reports Server (NTRS)

    Foster, J. C.; Doupnik, J. R.; Stiles, G. S.

    1980-01-01

    The temporal evolution of the ionospheric density enhancement produced by a widespread relativistic electron precipitation (REP) has been observed with the Chatanika Radar. The REP was associated with a substorm particle energization event, and both the ionospheric absorption and density perturbation exhibited an approximately 90 min periodicity associated with the particles' longitudinal drift. A 80-keV characteristic energy for the precipitating electrons is deduced from ground-based and satellite data. At the maximum of the event, electrons deposited approximately 50 ergs/sq cm per sec in the ionosphere, producing a peak density of 500,000/cu cm at 89 km altitude. At that time the radar observed densities greater than 100,000/cu cm between 70 km and 110 km altitude and riometer absorption at 30 MHz was approximately 12 db.

  12. Travelling ionospheric disturbance over California mid 2000

    NASA Astrophysics Data System (ADS)

    Hawarey, M.

    2006-01-01

    In this paper, the GPS data collected by more than 130 permanent GPS stations that belong to the Southern California Integrated GPS Network (SCIGN) around the launch of a Minuteman-II missile on 8 July 2000 (UTC) is processed to reveal traveling ionospheric disturbance (TID) all over the network on average 15 min after the launch. This TID was initially perceived to be excited by the launch itself, but this conclusion is challenged by the propagation direction. This is because this TID seems to travel towards the air force base from where the launch took place, not far away from it. This challenge is based on the assumption that TID is occurring at one single ionospheric altitude. While the nature of ionosphere supports such horizontally-guided propagation, multi-altitude ionospheric pierce points are hypothesized, which would support the suggestion that detected TID is excited by the missile launch itself, despite the apparent reverse direction of propagation. The overall analysis rules out any extra-terrestrial sources like solar flares, or seismic sources like earthquakes, which confirms the conclusion of TID excitation by the launch. There is apparent coherence of the TID for about 45 min and the propagation speed of TID within the layer of ionosphere is calculated to be approximately equal to 1230 m/s. While the usual assumption for TID is that they occur around an altitude of 350 km, such sound speed can only occur at much higher altitudes. Further research is recommended to accurately pinpoint the ionospheric pierce points and develop an algorithm to locate the source of TID in case it is totally unknown.

  13. GNSS data filtering optimization for ionospheric observation

    NASA Astrophysics Data System (ADS)

    D'Angelo, G.; Spogli, L.; Cesaroni, C.; Sgrigna, V.; Alfonsi, L.; Aquino, M. H. O.

    2015-12-01

    In the last years, the use of GNSS (Global Navigation Satellite Systems) data has been gradually increasing, for both scientific studies and technological applications. High-rate GNSS data, able to generate and output 50-Hz phase and amplitude samples, are commonly used to study electron density irregularities within the ionosphere. Ionospheric irregularities may cause scintillations, which are rapid and random fluctuations of the phase and the amplitude of the received GNSS signals. For scintillation analysis, usually, GNSS signals observed at an elevation angle lower than an arbitrary threshold (usually 15°, 20° or 30°) are filtered out, to remove the possible error sources due to the local environment where the receiver is deployed. Indeed, the signal scattered by the environment surrounding the receiver could mimic ionospheric scintillation, because buildings, trees, etc. might create diffusion, diffraction and reflection. Although widely adopted, the elevation angle threshold has some downsides, as it may under or overestimate the actual impact of multipath due to local environment. Certainly, an incorrect selection of the field of view spanned by the GNSS antenna may lead to the misidentification of scintillation events at low elevation angles. With the aim to tackle the non-ionospheric effects induced by multipath at ground, in this paper we introduce a filtering technique, termed SOLIDIFY (Standalone OutLiers IDentIfication Filtering analYsis technique), aiming at excluding the multipath sources of non-ionospheric origin to improve the quality of the information obtained by the GNSS signal in a given site. SOLIDIFY is a statistical filtering technique based on the signal quality parameters measured by scintillation receivers. The technique is applied and optimized on the data acquired by a scintillation receiver located at the Istituto Nazionale di Geofisica e Vulcanologia, in Rome. The results of the exercise show that, in the considered case of a noisy

  14. Derivation of a planetary ionospheric storm index

    NASA Astrophysics Data System (ADS)

    Gulyaeva, T. L.; Stanislawska, I.

    2008-09-01

    The planetary ionospheric storm index, Wp, is deduced from the numerical global ionospheric GPS-IONEX maps of the vertical total electron content, TEC, for more than half a solar cycle, 1999-2008. The TEC values are extracted from the 600 grid points of the map at latitudes 60° N to 60° S with a step of 5° and longitudes 0° to 345° E with a step of 15° providing the data for 00:00 to 23:00 h of local time. The local effects of the solar radiant energy are filtered out by normalizing of the TEC in terms of the solar zenith angle χ at a particular time and the local noon value χ0. The degree of perturbation, DTEC, is computed as log of TEC relative to quiet reference median for 27 days prior to the day of observation. The W-index map is generated by segmentation of DTEC with the relevant thresholds specified earlier for foF2 so that 1 or -1 stands for the quiet state, 2 or -2 for the moderate disturbance, 3 or -3 for the moderate ionospheric storm, and 4 or -4 for intense ionospheric storm at each grid point of the map. The planetary ionospheric storm Wp index is obtained from the W-index map as a latitudinal average of the distance between maximum positive and minimum negative W-index weighted by the latitude/longitude extent of the extreme values on the map. The threshold Wp exceeding 4.0 index units and the peak value Wpmax≥6.0 specify the duration and the power of the planetary ionosphere-plasmasphere storm. It is shown that the occurrence of the Wp storms is growing with the phase of the solar cycle being twice as much as the number of the magnetospheric storms with Dst≤-100 nT and Ap≥100 nT.

  15. Does the Precipitation of Solar Wind Plasma Cause the Ionospheric Upwellings Detected by MARSIS on the Dayside of Mars?

    NASA Astrophysics Data System (ADS)

    Dieval, C.; Morgan, D. D.; Andrews, D. J.; Duru, F.; Gurnett, D. A.

    2014-12-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the Mars Express spacecraft possesses an ionospheric mode, which is used for local and remote sounding measurements of the Martian topside ionosphere. Ideally, the sounding pulse transmitted by MARSIS gives a vertical reflection from the horizontally stratified ionosphere, down to the ionospheric peak. In practice, this is usually the case, however oblique reflections are also detected. These oblique reflections are often found in regions where the remanent crustal magnetic field is nearly vertical and the sources of reflections are often at a higher apparent altitude than the surrounding ionosphere for the same electron density level. There are recurring observations of such ionospheric upwellings during repeated passes of Mars Express above certain regions over time periods of tens of days. An increased ionospheric scale height seems to create these plasma bulges. A possible cause is a localized heating of the neutral atmosphere due to the entrance of solar wind plasma through the magnetic cusps. We test this explanation by using in situ measurements of electron energy distributions made by the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) onboard Mars Express. The statistical study considers dayside oblique echoes (solar zenith angle ≤ 90°) with spacecraft altitude ≤1100 km, for orbits with sufficient MARSIS data coverage and corresponding to a criterion of repetitive passes above a given region. We keep only oblique echoes which are no further below than 10 km in apparent altitude compared to the surrounding ionosphere (most of the cases), to ensure the echoes most likely come from near the vertical direction, at the time of closest approach. Finally we take the oblique echoes with simultaneous ASPERA-3 data, with short time intervals (up to 2 minutes) before and after the time of closest approach. This leaves 761 oblique echoes. The intervals are then manually

  16. Radiowave Imaging of Ionospheric Electron Dynamics

    NASA Astrophysics Data System (ADS)

    van Bavel, Gregory Hugh

    1998-12-01

    This dissertation is a study of disturbances in the polar ionosphere. A relative ionospheric opacity meter (riometer) is a radio frequency instrument that enables the remote sensing of ionospheric disturbances by recording variations in the cosmic radio noise power received at a terrestrial antenna. The Imaging Riometer for Ionospheric Studies (IRIS) produces images of relative ionospheric opacity. In the ionosphere, the attenuation of a radio signal's amplitude is proportional to the electron number density n and the effective collision frequency ν. Therefore, a riometer is sensitive to variations of the product n/nu, but their effects are not separated. The theory of HF radiowave attenuation in a cold magetoplasma and electron continuity yield a pair of uni-directional wave equations that couple the dynamics of cosmic radio noise absorption to the vertical mean value of ν. These equations, and some simplifying assumptions, are the basis of a data analysis that transforms IRIS images into physical quantities related to the absorbing ionospheric electrons: mean velocity, mean effective collision frequency, net production rate and column density. A critical test case and coincident auroral observations support the reliability of the general results of the data analysis. Variations in the mean flow velocity indicate that the ionosphere is not in equilibrium. The mean effective collision frequency shows significant structural variations over 100 km and 1 minute intervals. Column density depletions lead enhancements in a geomagnetic poleward drift, while a net production region moves with the column density enhancement and intensifies as the pole-ward motion ceases. Regions of persistent electron production or loss are found where the collision frequency is relatively low, and specific locations can oscillate between net production and loss with periods of about 1 to 2 minutes. It is found that the spatial structure of a riometer image is chiefly determined by the

  17. Ionospheric tomography using the FORTE satellite

    SciTech Connect

    Murphy, T.C.

    1993-08-01

    The possibility of obtaining ionospheric profile data via tomographic techniques has elicited considerable interest in recent years. The input data for the method is a set of total electron content measurements along intersecting lines of sight which form a grid. This can conveniently be provided by a fast-moving satellite with a VHF beacon which will generate the multiple paths needed for effective tomography. Los Alamos and Sandia National Laboratories will launch and operate the FORTE satellite for the US Department of Energy, with launch scheduled in 1995. FORTE will provide such a beacon. Additionally, wideband VHF receivers aboard the satellite will allow corraborative measurements of ionospheric profile parameters in some cases.

  18. Lunar Variation of Several Ionospheric Parameters.

    DTIC Science & Technology

    1981-09-30

    ALBERCA , J 0 CARDUS, E GALDON AFOSR-79-0114 UNCLASSIFIED SCIENTIFIC-Z EOARD-TR-212 ML 111a 11m I.8 II1JIL2 111.6__II MICROCOPY RESOLUTION TEST CHART...X4 SCIENTIFIC REPORT No 2 LUNAR VARIATION OF SEVERAL IONOSPHERIC PARAMETERS L. F. Alberca S. I. J. 0. Card6s 5.1. * E. Gald6n S.I1. * LLCTE... Alberca , e.I. J.O. Cardds, s.1. E. Gald6n, 8., OBSERVATORIO DEL EBR0 IONOSPHERIC SECTION ROQUETES (Tarragona) Spain THE RESEARCH REPORTED IN THIS

  19. Model of traveling ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Fedorenko, Yury P.; Tyrnov, Oleg F.; Fedorenko, Vladimir N.; Dorohov, Vasiliy L.

    2013-10-01

    A multiscale semi-empirical model of traveling ionospheric disturbances (TIDs) is developed. The model is based on the following assumptions: (1) TIDs are generated by acoustic-gravity waves (AGWs) and propagate as pressure waves; (2) time intervals between adjacent extrema of atmospheric pressure oscillations in a disturbance source are constant; (3) the pressure extrema propagate from the source up to ~14 000 km at a constant horizontal velocity; (4) the velocity of each extremum is determined only by its number in a TID train. The model was validated using literature data on disturbances generated by about 20 surface and high-altitude nuclear explosions, two volcano explosions, one earthquake and by energetic proton precipitation events in the magnetospheric cusp of the northern hemisphere. Model tests using literature data show that the spatial and temporal TID periods may be predicted with an accuracy of 12%. Adequacy of the model was also confirmed by our observations collected using transionospheric sounding. The following TID parameters: amplitudes, horizontal spatial periods, and a TID front inclination angle in a vertical plane are increasing as the distance between an AGW and the excitation source is increasing. Diurnal and seasonal variability of the TID occurrence, defined as ratio of TID events to the total number of observations for the corresponding period, is not observed. However, the TID occurrence was growing from ~50% in 1987 to ~98% in 2010. The results of other studies asserting that the TID occurrence does not depend on the number of sunspots and magnetic activity are confirmed. The TID occurrence has doubled over the period from 1987 to 2010 indicating increasing solar activity which is not associated with sunspot numbers. The dynamics of spatial horizontal periods was studied in a range of 150-35 000 km.

  20. Studing Solar Flare Effects on Ionosphere Using AWESOME Receiver

    NASA Astrophysics Data System (ADS)

    Mustafa, Famil; Babayev, Elchin; Alekperov, Ilgar

    2015-08-01

    Ground based observations of Extremely Low Frequency (ELF) / Very Low Frequency (VLF) (300 Hz 30 kHz) waves are considered as an important remote sensing tool for the investigation of the ionosphere and the magnetosphere. VLF waves find their origin in various natural and artificial phenomena; the natural sources include thunderstorms, lightning and associated phenomena. Sub-ionospheric VLF transmissions propagating inside the Earth-ionosphere wave-guide is also being widely used for investigating sudden ionospheric perturbations (SIDs) in lower part of the ionosphere.

  1. Absorption of whistler mode waves in the ionosphere of Venus

    NASA Technical Reports Server (NTRS)

    Taylor, W. W. L.; Scarf, F. L.; Russell, C. T.; Brace, L. H.

    1979-01-01

    It is shown that whistler mode waves from the ionosheath of Venus are absorbed by Landau damping at the dayside ionosphere boundary. This process heats the ionospheric electrons and it may provide an important energy input into the dayside ionosphere. Cyclotron damping of the waves does not occur in the same region. However, Landau damping of ionosheath waves is apparently not an important energy source in the nightside ionosphere. Impulsive events in the nightside ionosphere seem to fall into two classes: (1) lightning signals (near periapsis) and (2) noise, which may be caused by gradient or current instabilities.

  2. Absorption of whistler mode waves in the ionosphere of venus.

    PubMed

    Taylor, W W; Scarf, F L; Russell, C T; Brace, L H

    1979-07-06

    It is shown that whistler mode waves from the ionosheath of Venus are absorbed by Landau damping at the dayside ionosphere boundary. This process heats the ionospheric electrons and it may provide an important energy input into the dayside ionosphere. Cyclotron damping of the waves does not occur in the same region. However, Landau damping of ionosheath waves is apparently not an important energy source in the nightside ionosphere. Impulsive events in the nightside ionosphere seem to fall into two classes: (i) lightning signals (near periapsis) and (ii) noise, which may be caused by gradient or current instabilities.

  3. Modifications of the ionosphere prior to large earthquakes: report from the Ionosphere Precursor Study Group

    NASA Astrophysics Data System (ADS)

    Oyama, K.-I.; Devi, M.; Ryu, K.; Chen, C. H.; Liu, J. Y.; Liu, H.; Bankov, L.; Kodama, T.

    2016-12-01

    The current status of ionospheric precursor studies associated with large earthquakes (EQ) is summarized in this report. It is a joint endeavor of the "Ionosphere Precursor Study Task Group," which was formed with the support of the Mitsubishi Foundation in 2014-2015. The group promotes the study of ionosphere precursors (IP) to EQs and aims to prepare for a future EQ dedicated satellite constellation, which is essential to obtain the global morphology of IPs and hence demonstrate whether the ionosphere can be used for short-term EQ predictions. Following a review of the recent IP studies, the problems and specific research areas that emerged from the one-year project are described. Planned or launched satellite missions dedicated (or suitable) for EQ studies are also mentioned.

  4. Studies of ionospheric plasma and electrodynamics and their application to ionosphere-magnetosphere coupling

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1988-01-01

    The contribution of the Dynamics Explorer (DE) program to the study of small-scale structure in the equatorial ionospheric number density and the bulk motion of the plasma in the equatorial ionosphere is considered. DE results have helped elucidate the role of E region and F region winds in decreasing the magnitude of variations in the east-west plasma drift at night, as a function of magnetic flux tube apex height, with increasing height above the altitude of the peak F region concentration. Other results concern the ionospheric convection pattern at high latitudes during periods of southward IMF, the magnetosphere/solar-wind interaction that may be involved in the production of the convection pattern, and the characteristics of the high-latitude ionospheric plasma motion during periods of northward IMF.

  5. The variability, morphology and outflow of Martian ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Barabash, S.; Winningham, D.

    2009-04-01

    ASPERA-3 measurements from Mars Express demonstrate that Martian ionospheric plasma escapes in a comet-like fashion. Low-energy (cold) ionospheric plasma is swept from the dayside, expanding into the nightside/tail of Mars. The primary energization processes brings ionospheric plasma to just above escape velocity (5 - 20 km/s). In analogy with the polar wind of the Earth, ionospheric plasma is expected to become energized by waves and electric fields generated by solar wind energy and momentum transfer processes. The rather symmetric and global comet-like escape of low-energy ionospheric plasma, streaming along the external sheath flow, suggest a "viscous-like" coupling between the sheath plasma and the expanding ionospheric plasma. The ionospheric ion outflow is very structured, fan-like and modulated in the ULF frequency range. The ionospheric densities measured vary correspondingly with time, altitude, latitude and local time. A similar variability of solar wind ions is found in the Martian magnetosheath. This implies that magnetosheath wave activity is involved, transferring energy and momentum to ionospheric ions. We demonstrate that the wave activity modulating ions and electrons, reaches down to the MEX pericenter (≈300 km), suggesting that heating/energization of ionospheric plasma extends deep into the ionosphere.

  6. A simplified traveling ionospheric disturbance (TID) specification model based on TID Detector Built In Texas (TIDDBIT) and GPS total electron content (TEC) measurements.

    NASA Astrophysics Data System (ADS)

    Duly, T. M.; Crowley, G.; Azeem, I.

    2015-12-01

    There is currently a great deal of interest in Traveling Ionospheric Disturbances (TIDs) from both an observational and modeling perspective, especially as they apply to operational systems that rely on nowcasting the ionospheric state. ASTRA has developed a new observational system to measure TID characteristics called TIDDBIT (TID Detector Built in Texas). TIDDBIT is a fully digital HF Doppler sounder that uses CW signals across a spaced array. TIDDBIT systems have been deployed in Texas, Virginia, Florida, Hawaii, and Peru. TIDDBIT measures the entire wave packet, including the horizontal and vertical phase propagation speeds as a function of TID period from the acoustic (1-min) to the gravity wave (10-90 min) part of the spectrum. It is desirable to be able to use these data to specify the TID structure not only at the measurement height, but to extend it in 3D to greater and lower heights, and beyond the immediate vicinity of the TIDDBIT system. We present a simplified model to specify TIDs based on the ion continuity equation for plasma density (Hooke 1970). Linearity of the neutral wind perturbations is assumed, and the different spectral components of the measured TID perturbations are added linearly. We use TID observations from the TIDDBIT sounder in Virginia and Peru as input into the model, and develop a 4D regional specification (spanning ~500 x 500 km in the horizontal direction and 90-1000 km altitude range) of both the perturbed electron density and the perturbed neutral wind from the corresponding atmospheric gravity wave (AGW). The model is also applied to TID measurements derived by GPS TEC measurements from the continental United States during the 11 March 2011 Tohoku Earthquake to study the theoretical launch angle of AGWs from the west coast of the United States.

  7. Electron temperature and heat flow in the nightside Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.; Brace, L. H.; Theis, R. F.; Mayr, H. G.

    1980-01-01

    A steady-state two-dimensional heat balance model is used to analyze the night side Venusian ionospheric electron temperatures given by the Pioneer Venus orbiter electron temperature probe. The energy calculation includes the solar EUV heating at the terminator, electron cooling to ions and neutrals, and heat conduction within the ionospheric plasma. An optimum magnetic field is derived by solving for the heat flux directions which force energy conservation while constrained by the observed temperatures within the range of 80-170 deg solar zenith angle and 160-170 km. The heat flux vectors indicate a magnetic field that connects the lower night side ionosphere to the day side ionosphere, and connects the upper ionosphere to the ionosheath. The lower ionosphere is heated through conduction of heat from the dayside, and the upper ionosphere is heated by the solar wind in the ionosheath with heat flowing downward and from the nightside to the day side.

  8. Ionospheric effects during severe space weather events seen in ionospheric service data products

    NASA Astrophysics Data System (ADS)

    Jakowski, Norbert; Danielides, Michael; Mayer, Christoph; Borries, Claudia

    Space weather effects are closely related to complex perturbation processes in the magnetosphere-ionosphere-thermosphere systems, initiated by enhanced solar energy input. To understand and model complex space weather processes, different views on the same subject are helpful. One of the ionosphere key parameters is the Total Electron Content (TEC) which provides a first or-der approximation of the ionospheric range error in Global Navigation Satellite System (GNSS) applications. Additionally, horizontal gradients and time rate of change of TEC are important for estimating the perturbation degree of the ionosphere. TEC maps can effectively be gener-ated using ground based GNSS measurements from global receiver networks. Whereas ground based GNSS measurements provide good horizontal resolution, space based radio occultation measurements can complete the view by providing information on the vertical plasma density distribution. The combination of ground based TEC and vertical sounding measurements pro-vide essential information on the shape of the vertical electron density profile by computing the equivalent slab thickness at the ionosonde station site. Since radio beacon measurements at 150/400 MHz are well suited to trace the horizontal structure of Travelling Ionospheric Dis-turbances (TIDs), these data products essentially complete GNSS based TEC mapping results. Radio scintillation data products, characterising small scale irregularities in the ionosphere, are useful to estimate the continuity and availability of transionospheric radio signals. The different data products are addressed while discussing severe space weather events in the ionosphere e.g. events in October/November 2003. The complementary view of different near real time service data products is helpful to better understand the complex dynamics of ionospheric perturbation processes and to forecast the development of parameters customers are interested in.

  9. Field-aligned electron density irregularities near 500 km. Equator to polar cap topside sounder Z mode observations

    NASA Astrophysics Data System (ADS)

    Benson, R. F.

    1984-04-01

    In addition to spread F, evidence for field-aligned electron density irregularities is commonly observed on Alouette 2 topside sounder ionograms recorded near perigee (500 km). This evidence is provided by distinctive signal returns from sounder-generated Z mode waves. At low latitudes these waves become guided in wave ducts caused by field-aligned electron density irregularities and give rise to strong long-duration echoes. At high latitudes, extending well into the polar cap, these Z mode waves (and stimulated electrostatic waves at the plasma frequency) produce a series of vertical bars on the ionogram display as the satellite traverses discrete field-aligned density structures. The radio frequency (RF) noise environment to be expected in the 400 to 500 km altitude region from low to high latitudes was examined by analyzing perigee Alouette 2 topside sounder data. All observed noise bands were scaled on nearly 200 topside sounder ionograms recorded near perigee at low, mid, and high latitude telemetry stations. The minimum and maximum frequencies of each noise band were entered into a data base or compuer analysis. The signals of primary interest in the perigee study were found to be sounder-generated.

  10. Field-aligned electron density irregularities near 500 km. Equator to polar cap topside sounder Z mode observations

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1984-01-01

    In addition to spread F, evidence for field-aligned electron density irregularities is commonly observed on Alouette 2 topside sounder ionograms recorded near perigee (500 km). This evidence is provided by distinctive signal returns from sounder-generated Z mode waves. At low latitudes these waves become guided in wave ducts caused by field-aligned electron density irregularities and give rise to strong long-duration echoes. At high latitudes, extending well into the polar cap, these Z mode waves (and stimulated electrostatic waves at the plasma frequency) produce a series of vertical bars on the ionogram display as the satellite traverses discrete field-aligned density structures. The radio frequency (RF) noise environment to be expected in the 400 to 500 km altitude region from low to high latitudes was examined by analyzing perigee Alouette 2 topside sounder data. All observed noise bands were scaled on nearly 200 topside sounder ionograms recorded near perigee at low, mid, and high latitude telemetry stations. The minimum and maximum frequencies of each noise band were entered into a data base or compuer analysis. The signals of primary interest in the perigee study were found to be sounder-generated.

  11. Femto-Satellite system for radio-occultation study of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Savio Bradford, Brandon; Gutierrez Cabello, Jordi

    This research project proposes the use of (a swarm of) Femto-Satellites in the study of Ionospheric properties using \\underline{Radio-Occultation} techniques. It makes use of GPS signals, a computing system, tiny on-board components and a data transfer module. This project is being done as a cheaper and lightweight alternative proposal to the higher cost, already running COSMIC program and other programs which use larger satellites to perform Radio-Occultation study of the Ionosphere. Being that these femto-satellites are capable of acting as a constellation, they will be able to provide higher accuracy radio-occultation readings of the Ionosphere due to the close proximity between each satellite positioned in low earth orbit. Important parameters attempted for this system include a weight of 100 grams per satellite system and an innovative power source using solar sails. The sails also serve to provide an anti-debris system of redundancy to make sure these tiny satellites don't add to the already alarming amount of space debris, in the event of a malfunction. Ultimately, having a large amount of tiny satellites serving to study the ionosphere at closer proximities and obtain more accurate results will give the scientific community a better understanding of the constant changes in the space environment at a given altitude. This could help humanity combat adverse changes in climate, which heavily affects some regions of agriculture. This could also help advance the scientific campaign against global warming, by providing real-time readings from different regions of the ionosphere.

  12. Simulating Storm Enhanced Densities (SEDs) Using Ionosphere-Plasmasphere-Electrodynamics (IPE) Model

    NASA Astrophysics Data System (ADS)

    Fedrizzi, M.; Maruyama, N.; Fuller-Rowell, T. J.; Richards, P. G.; Fang, T. W.; Codrescu, M.

    2015-12-01

    Storm-enhanced densities (SEDs) are increased ion concentrations seen in longitudinally narrow regions extending from middle latitudes to the polar cusp region. Signatures of SEDs have been observed in total electron content measurements obtained from networks of GPS receivers. They have also been observed as plasmaspheric plumes by the extreme ultraviolet imager onboard IMAGE spacecraft, and more recently by the Van Allen Probes. Various mechanisms have been suggested to explain these density enhancements. In order to assess these theories and advance the understanding of the processes causing the dynamical evolution of SEDs in the ionosphere, a global ionosphere-plasmasphere model with a realistic specification of storm time dependent electric field and neutral atmosphere is required. In this study, the recently developed Ionosphere-Plasmasphere-Electrodynamics (IPE) model is used to simulate the SED observed during the March 17th, 2013 geomagnetic storm event. The IPE model provides time dependent, global, three dimensional plasma densities for nine ion species, electron and ion temperatures, parallel and perpendicular velocities of ionosphere and plasmasphere. The geomagnetic storm high latitude drivers rely on the empirical models of the time-dependent Weimer magnetospheric convection and TIROS/NOAA auroral precipitation patterns. The neutral atmosphere composition and winds come from either empirical the MSIS and HWM models, or the Coupled model of the Thermosphere, Ionosphere, Plasmasphere and electrodynamics (CTIPe). The simulations are used to evaluate the relative importance between electric field, neutral wind and neutral composition in reproducing the SEDs. Furthermore, observations from ground and space are used to validate the model results.

  13. Global characteristics of the upper transition height derived from the topside Alouette/ISIS topside sounder electron density profiles, the Formosat-3/COSMIC density profiles and the IRI ion composition model

    NASA Astrophysics Data System (ADS)

    Truhlik, Vladimir; Triskova, Ludmila; Benson, Robert; Bilitza, Dieter; Chu, Philip; Richards, Phil G.; Wang, Yongli

    The upper transition height (Ht) (the altitude of the transition from heavy atomic ions to light ions or in the simplest form the transition from O+ to H+) is an important parameter, representing the boundary between the ionosphere and the plasmasphere. Ht is very sensitive to various geophysical parameters, like solar and magnetic activity and strongly depends on latitude and local time. There were numerous studies of this parameter in past decades. In spite of these efforts, no model satisfactorily represents this parameter so far. Moreover, surprising evidence of very low transition heights during the last prolonged solar minimum, of a level never obtained before, have been reported. We investigate the upper transition height on the global scale. We made progress in processing large data sets of Ht deduced from the Alouette/ISIS topside sounder and from the Formosat-3/COSMIC vertical electron-density profiles Ne(h) using the theoretical Global Plasma Ionosphere Density (GPID) model (Webb and Essex, 2004) and a revised non-linear function describing the scale height vs. altitude (Titheridge, 1976) to fit the vertical density profiles to the observed profiles and to determine the upper transition height. Since both methods require the plasma temperatures and their gradients as input, these are calculated using the IRI2012 model. Both methods are verified using a large amount of electron and ion density profiles simulated by the FLIP theoretical model and their accuracy is discussed. We compare the results from Alouette/ISIS and Formosat-3/COSMIC and present a global distribution of the calculated Ht and its dependence on geophysical parameters. Finally we compare it with Ht calculated using the IRI ion composition model. Titheridge, J.E., 1976. Ion Transition Heights from Topside Electron-Density Profiles. Planetary and Space Science 24 (3), 229-245. Webb, P.A., Essex, E.A., 2004. A dynamic global model of the plasmasphere. Journal of Atmospheric and Solar

  14. Tropical Storm Beryl as Observed by NASA's Spaceborne Atmospheric Infrared Sounder (AIRS)