[1] Atmospheric gravity waves have been a subject of intense research activity in recent years because of their myriad effects and their major contributions to atmospheric circulation, structure, and variability. Apart from occasionally strong lower-atmospheric effects, the major wave influences occur in the middle atmosphere, between ∼ 10 and 110 km altitudes because of decreasing density and increasing wave amplitudes with altitude. Theoretical, numerical, and observational studies have advanced our understanding of gravity waves on many fronts since the review by Fritts [1984a]; the present review will focus on these more recent contributions. Progress includes a better appreciation of gravity wave sources and characteristics, the evolution of the gravity wave spectrum with altitude and with variations of wind and stability, the character and implications of observed climatologies, and the wave interaction and instability processes that constrain wave amplitudes and spectral shape. Recent studies have also expanded dramatically our understanding of gravity wave influences on the large-scale circulation and the thermal and constituent structures of the middle atmosphere. These advances have led to a number of parameterizations of gravity wave effects which are enabling ever more realistic descriptions of gravity wave forcing in large-scale models. There remain, nevertheless, a number of areas in which further progress is needed in refining our understanding of and our ability to describe and predict gravity wave influences in the middle atmosphere. Our view of these unknowns and needs is also offered.

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Gravity wave dynamics and effects in the middle atmosphere

https://www.lpl.arizona.edu/~yelle/eprints/Yelle04b.pdf

Aeronomy of extra-solar giant planets at small orbital distances

Atmosphere: State of the Art and Challenges Barbara Nozier̀e,*,† Markus Kalberer,*,‡ Magda Claeys,* James Allan, Barbara D’Anna,† Stefano Decesari, Emanuela Finessi, Marianne Glasius, Irena Grgic,́ Jacqueline F. Hamilton, Thorsten Hoffmann, Yoshiteru Iinuma, Mohammed Jaoui, Ariane Kahnt, Christopher J. Kampf, Ivan Kourtchev,‡ Willy Maenhaut, Nicholas Marsden, Sanna Saarikoski, Jürgen Schnelle-Kreis, Jason D. Surratt, Sönke Szidat, Rafal Szmigielski, and Armin Wisthaler †Ircelyon/CNRS and Universite ́ Lyon 1, 69626 Villeurbanne Cedex, France ‡University of Cambridge, Cambridge CB2 1EW, United Kingdom University of Antwerp, 2000 Antwerp, Belgium The University of Manchester & National Centre for Atmospheric Science, Manchester M13 9PL, United Kingdom Istituto ISAC C.N.R., I-40129 Bologna, Italy University of York, York YO10 5DD, United Kingdom University of Aarhus, 8000 Aarhus C, Denmark National Institute of Chemistry, 1000 Ljubljana, Slovenia Johannes Gutenberg-Universitaẗ, 55122 Mainz, Germany Leibniz-Institut für Troposphar̈enforschung, 04318 Leipzig, Germany Alion Science & Technology, McLean, Virginia 22102, United States Max Planck Institute for Chemistry, 55128 Mainz, Germany Ghent University, 9000 Gent, Belgium Finnish Meteorological Institute, FI-00101 Helsinki, Finland Helmholtz Zentrum München, D-85764 Neuherberg, Germany University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States University of Bern, 3012 Bern, Switzerland Institute of Physical Chemistry PAS, Warsaw 01-224, Poland University of Oslo, 0316 Oslo, Norway

/pdf/the-molecular-identification-of-organic-compounds-in-the-1rs6wk4d8f.pdf

The molecular identification of organic compounds in the atmosphere : state of the art and challenges

Global warming is expected to drive increasing extreme sea levels (ESLs) and flood risk along the world's coastlines. In this work we present probabilistic projections of ESLs for the present century taking into consideration changes in mean sea level, tides, wind-waves, and storm surges. Between the year 2000 and 2100 we project a very likely increase of the global average 100-year ESL of 34-76 cm under a moderate-emission-mitigation-policy scenario and of 58-172 cm under a business as usual scenario. Rising ESLs are mostly driven by thermal expansion, followed by contributions from ice mass-loss from glaciers, and ice-sheets in Greenland and Antarctica. Under these scenarios ESL rise would render a large part of the tropics exposed annually to the present-day 100-year event from 2050. By the end of this century this applies to most coastlines around the world, implying unprecedented flood risk levels unless timely adaptation measures are taken.

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Global probabilistic projections of extreme sea levels show intensification of coastal flood hazard.

Forcing of the ionosphere by waves from below

Venus mountain waves in the upper atmosphere simulated by a time-invariant linear full-wave spectral model

A therapeutic optimization platform is described that encompasses a bio data filter interpretation apparatus for the purpose of selecting, validating and optimizing digital health content by way of linking the clinician and patient with meaningful medical data.

Bio Data Filter Interpretation Apparatus

Ground-based Global Positioning System (GPS) measurements of ionospheric Total Electron Content (TEC) show variations consistent with atmospheric internal gravity waves caused by ocean tsunamis. We have observed such traveling ionospheric disturbances (TIDs) following recent seismic events, including the Tohoku tsunami of March 11, 2011. We analyze fluctuations correlated in time, space, and wave properties with this tsunami in TEC estimates processed using JPL’s Global Ionospheric Mapping Software. The TEC estimates were band-pass filtered to remove ionospheric TEC variations with periods outside the typical range of internal gravity waves caused by tsunamis. Observable variations in TEC appear correlated with the Tohoku tsunami near the epicenter, at Hawaii, and near the west coast of North America. Disturbance magnitudes are 1-10% of the background TEC value. Observations near the epicenter are compared to estimates of expected tsunami-driven TEC variations produced by Embry Riddle Aeronautical University’s Spectral Full Wave Model, an atmosphere-ionosphere coupling model, and found to be in good agreement. The potential exists to apply these detection techniques to real-time GPS TEC data, providing estimates of tsunami speed and amplitude that may be useful for future early warning systems.

Observing Tsunamis in the Ionosphere Using Ground Based GPS Measurements

Introduction. Natural hazards, including earthquakes, volcanic eruptions, and tsunamis, have been significant threats to humans throughout recorded history. The Global Positioning System satellites have become primary sensors to measure the effects of such natural hazards. Signatures in the GPS data include seismic deformation displacements, co-seismic vertical displacements, and real-time ocean buoy positioning estimates. Another way to use GPS observables is to measure and monitor ionospheric total electron content (TEC) variations generated by post-seismic atmospheric disturbances caused by earthquakes, volcanic eruptions, tsunamis, meteors and nuclear explosions [e.g., Artru et al., 2005].

Prior JPL Work. Advances in very high precision ionospheric GPS data processing at JPL have demonstrated that ground-based GPS receivers are capable of detecting TEC perturbations generated by atmospheric acoustic and gravity waves [Komjathy et al., 2012]. The 2011 Tohoku earthquake and tsunami data processing results have, for instance, demonstrated that the gravity-wave-derived TEC perturbations are visible 45 minutes after the earthquake [Galvan et al., 2012]. Applying JPL’s data processing techniques to multiple events, we have found that a 2004 volcanic eruption in Japan showed approximately 1-minute period waves in ionospheric TEC, whereas the September 2009 earthquake near Samoa produced signatures with an 8-minute period [Galvan et al., 2011]. There remains much to learn about the characteristics of these interactions between the Earth’s surface and ionosphere, including how and why they differ from one event to the next.

Recent Natural Hazard Event of High Interest. The Chelyabinsk meteor provided a unique opportunity to observe TEC disturbances generated by a fireball in the atmosphere. The small asteroid entered the atmosphere at 3:20 UT on February 15, 2013 moving at a speed of about 20 km/s. The object, with an almost 20 meters in diameter, then burst into pieces at a height of 30-50 km above the ground. Large fragments moving at a high speed caused a powerful flash and a strong shockwave, with most of the meteor’s energy released at a height of 5 to 15 km above the earth. 

Technical Approach. We use JPL’s PyIono package (a bias-fixing algorithm) to generate high-precision calibrated TEC measurements. Calibrating TEC measurements serves multiple purposes for us including quality checking (QC) of processed data, leveling the phase measurements using pseudoranges and comparing modeled TEC perturbations with measured ones [Mannucci et al, 1998]. Obtaining absolute TEC values is useful to understand background conditions for the perturbations [e.g., Komjathy et al, 2005]. However, we are primarily interested in monitoring small-scale variations in ionospheric electron density, hence the changes in TEC are of interest, rather than absolute TEC values. Subsequently, JPL’s PyIono uses TEC observations to compute de-trended TEC data. A Butterworth band-pass filter (corresponding to waves with periods between 33 and 3.3 minutes ranging between 0.5 and 5 mHz) is applied to focus on acoustic and gravity wave generated TEC observations. This type of filtering allows us to more easily detect perturbations within an expected range of frequencies, which we can infer from previous observations of tsunami periods, for example [Galvan et al., 2012].

Summary and Anticipated Results. We have processed data from 23 GPS stations within a radius of 1500 km from the impact location in Russia for February 15 and the surrounding days. Initial results of monitoring TEC perturbations using the JPL technique suggest a strong impact of the individual explosions on the ionosphere. Furthermore, we observed a statistically significant correlation between the reported meteor trajectory and the ionospheric signatures measured by GPS. Preliminary modeling results of wave structures are presented and compared with the observed perturbations to investigate the possible generation and propagation of waves associated with this unique hazard event.

Acknowledgements. The authors would like to thank NASA Headquarters and the Earth Science and Interior NASA ROSES Grant (NNH07ZDA001N-ESI). This research was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration.

REFERENCES

Artru, J., V. Ducic, H. Kanamori, P. Lognonne, and M. Murakami (2005), Ionospheric detection of gravity waves induced by tsunamis, Geophysical Journal International, 160, 840–848, 10.1111/j.1365-246X.2005.02552.x.

Galvan, D. A., A. Komjathy, M. P. Hickey, P. Stephens, J. Snively, Y. Tony Song, M. D. Butala, and A. J. Mannucci (2012), Ionospheric Signatures of Tohoku-Oki Tsunami of March 11, 2011: Model Comparisons Near the Epicenter. Radio Science, 2012RS005023.

Galvan, D. A., A. Komjathy, M. P. Hickey, and A. J. Mannucci (2011), The 2009 Samoa and 2010 Chile tsunamis as observed in the ionosphere using GPS total electron content, Journal of Geophysical Research (Space Physics), 116, A06, 318, 10.1029/2010JA016204. http://dx.doi.org/10.1029/2010JA016204

Komjathy, A., L. Sparks, B. D. Wilson, and A. J. Mannucci (2005), Automated daily processing of more than 1000 ground-based GPS receivers for studying intense ionospheric storms, Radio Sci., 40, RS6006, doi:10.1029/2005RS003279.

Komjathy, A., D.A. Galvan, P. Stephens, M.D. Butala, V. Akopian, B.D. Wilson, O. Verkhoglyadova, A.J. Mannucci, and M. Hickey (2012). “Detecting Ionospheric TEC Perturbations Caused by Natural Hazards Using a Global Network of GPS Receivers: the Tohoku Case Study.” Earth Planets Space, Vol. 64, 1-8, 2012.

Mannucci, A. J., B. D. Wilson, D. N. Yuan, C. H. Ho, U. J. Lindqwister, and T. F. Runge (1998), A global mapping technique for GPS-derived ionospheric total electron content measurements, Radio Science, 33, 565–582, 10.1029/97RS02707.

Investigating Natural Hazards Using GNSS Measurements: The Chelyabinsk Meteor Ionospheric Impact

/pdf/applications-of-the-technology-acceptance-model-to-wcorrysa4i.pdf

Michael P. Hickey

Papers

Venus mountain waves in the upper atmosphere simulated by a time-invariant linear full-wave spectral model

Bio Data Filter Interpretation Apparatus

Observing Tsunamis in the Ionosphere Using Ground Based GPS Measurements

Investigating Natural Hazards Using GNSS Measurements: The Chelyabinsk Meteor Ionospheric Impact

Applications of the Technology Acceptance Model to Integration of the Automatic Ground Collision Avoidance System in Fighter Aircraft Operations