National Academies Press: OpenBook
« Previous: 1 Introduction
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

2

Mesosphere, Thermosphere, and Ionosphere

Presentations and discussions at the workshop highlighted the particular potential of ionospheric modification experiments to advance understanding of the mesosphere-lower thermosphere (MLT) and thermosphere regions of the atmosphere, with which the ionosphere is collocated. It was noted that the state parameters of the neutral gas in this region are difficult to measure with ground-based instruments, and the measurements that are possible are often poorly resolved in range or time, or available only within narrow altitude ranges. In particular, a workshop participant noted that neutral winds and densities in the thermosphere are poorly specified, introducing uncertainty into virtually all lines of theoretical investigation in aeronomy. Moreover, because neutral winds and densities control satellite drag, their poor specification was said to have important operational consequences.

It was noted by a participant that ionospheric modifications can also be used to explore coupling between neutral and charged species, because the radio frequency (RF) directly pumps the electrons, but neutral species are responsible for the subsequent relaxation back to radiative and chemical equilibrium. Further, it was asserted that heating experiments can explore this coupling more systematically and over a broader range of conditions than would be otherwise possible. Plasma-neutral coupling is one of the central themes of the National Science Foundation (NSF) Coupling, Energetic, and Dynamics of Atmospheric Regions (CEDAR) program.

Diagnostics generally monitor how the upper atmosphere responds to both RF heating and to its cessation. Ground-based instruments measure airglow, scattered radio signals, and stimulated radio signals from the modified volume. This information allows estimates of neutral winds, densities, temperatures, composition, plasma drifts, and rates of diffusion and cooling.

RECENT RESEARCH HIGHLIGHTS1

Multipolar Diffusion

At the workshop, the utility of ionospheric modification for understanding natural aeronomic processes was said to be exemplified by research into polar mesospheric summer echoes (PMSEs). PMSE refers to coherent radar scatter from thin layers in the polar summer mesosphere where charged dust particles and ice crystals associated with polar mesospheric clouds are present. The echoes arise from fluctuations in electron density driven by neutral atmospheric turbulence. It was noted by a workshop participant that the puzzle of how electron density fluctuations at small scale sizes could be sustained in the presence of ordinary ambipolar diffusion was resolved with the help of heating experiments.

In these experiments, an overshoot in echo intensity was consistently observed after heater turn-off (Havnes et al., 2003; Havnes, 2004). The overshoot led to a belated appreciation of multi-polar diffusion, a fundamental process in multi-component plasmas. Mahmoudian et al. (2011) accounted for

__________________

1 This section includes recent research cited by one or more participants as being particularly noteworthy.

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

the time history of the echoes by modeling temperature-dependent multipolar diffusion, charging, and recombination processes. According to one workshop participant, the result substantially advanced understanding of mesospheric turbulence, chemistry, and transport.

Sporadic E-Layer Patches

Another example cited at the workshop in which ionospheric modification facilitated discovery science in aeronomy concerns the morphology of sporadic E ionization layers. These layers, which were evident in the earliest days of radio, are known often to be non-blanketing and patchy, but observers note that conventional remote sensing instrumentation affords no easy way to image their horizontal structure. Bernhardt et al. (2003) introduced an imaging method, termed “radio-induced aurora,” or RIA, that combines RF heating with optical imaging.

Paul Bernhardt and others at the workshop discussed how ionospheric modification induces enhanced optical emissions via induced electron impact on neutral species that can be used as a diagnostic of background aeronomic processes. Both thermal and suprathermal processes are believed to be at work, with red-line excitation through direct electron heating and green-line excitation through electron acceleration. The red-line emission has a lower excitation energy and dominates green-line emission at F-region altitudes. Since the red-line emission is collisionally quenched at E-region altitudes, however, the green line dominates there.

RIA involves emitting pump-mode radiation at a frequency below the F-region critical frequency. Where there are no sporadic E-layer patches, the radiation propagates into the F region and produces red-line emissions at the F-region interaction height. Where there are sporadic E-layer patches, however, the pump-mode radiation interacts in the E layer. Not only does this produce gaps or “shadows” in the red-line emissions, it also produces green-line emission at E region altitudes. Bernhardt et al. (2003) used this technique to reveal kilometric structure in sporadic E layers over Arecibo.

Neutral Wind and Diffusion

Presentations at the workshop included references to combining RF heating with airglow imaging as a way to measure the neutral wind and diffusivity in the thermosphere. This method involves observing clouds of metastable O(1D) atoms over the heater after heating is discontinued. During this time, these atoms drift with the neutral wind and spread under the influence of diffusion, all the time decaying by radiation and collisional quenching. Using airglow imagery of bright, distinct clouds created by ionospheric modification, Bernhardt et al. (2012) estimated the drift velocity, diffusion rate, and quenching rate of the O(1D) atoms, in effect using ionospheric modification to perform a kind of repeatable chemical-release experiment.

HAARP-Induced Ionization (“Artificial Ionization”)

As noted in Chapter 1, Todd Pedersen and colleagues (Pedersen et al., 2010) recently demonstrated the capability of the High Frequency Active Auroral Research Program’s (HAARP’s) 3.6-MW transmitter to produce significant artificial plasma in the upper atmosphere. In addition to their fundamental interest, it was pointed out that these results could have important practical implications in communication and over-the-horizon radar as they present the possibility of creating long-path propagation channels on demand that would be otherwise unavailable. The artificial “layers” (the structure of these enhanced ionization regions is an area of current study) are also highly turbulent and so could be used to inhibit as well as promote long-path radio-wave propagation, depending on the desired application.

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

FUTURE OPPORTUNITIES

Summarized below from workshop presentations, and with additional references added for clarity, are what some participants described as the most promising techniques for basic and applied research into the MLT, thermosphere, and ionosphere using ionospheric modification.

Neutral Density

At the workshop, Elizabeth Kendall described NSF-funded research that has shown—using techniques that are at a research stage and not routine measurement by any means—that ionospheric modification experiments coupled with airglow observations can also be used to estimate neutral density. The long radiative lifetime of O(1D) means that it is controlled by collisional deactivation (quenching). The quenching rate, in turn, varies with the density of the neutral species in the thermosphere, so, in principle, it is possible to estimate density profiles. The technique requires optical triangulation and the ability to discern emissions from different altitudes. Gustavsson et al. (2001) used a tomographic approach to estimate the decay time of O(1D) as a function of altitude. Kalogerakis et al. (2009) went further, using the methodology to estimate density profiles of atomic oxygen, which they found dominates the quenching rate above about 200 km.

A workshop participant noted that for all of the methodologies under discussion, knowledge of the ionospheric interaction height is essential for accurate data interpretation. Ionospheric density profiles provided by an incoherent scatter radar (ISR) were said to be the most accurate source of this information. Moreover, electron temperature profiles from an ISR, being diagnostic of electron heating and acceleration, were said to provide vital context for interpreting artificial airglow data. Thus, this researcher stated, quantitatively accurate neutral density profiles at HAARP will most likely require a collocated ISR.

Winds and Temperatures

At the workshop, it was noted that several researchers have suggested a technique for studying the background ionosphere and thermosphere via artificial periodic inhomogeneities (APIs) (Belikovich et al., 1975; Fejer et al., 1984; Rietveld et al., 1996; Djuth et al., 1997; Bakhmet’eva and Belikovich, 2007). In this technique, high-power polarized (X- and O-mode) heating is used to induce very weak variations in the ionospheric index of refraction that follow the structure of the heating standing-wave pattern. Horizontally stratified, vertically periodic structure is thus induced at altitudes from the D region (starting at about 50 km) through the reflection height. Inhomogeneity is created by a combination of ponderomotive and thermal forcing and by photochemical effects, and possibly additional processes.

Once created, the ionospheric structure is diagnosed using HF sounding at frequencies calculated to match to the probe signal to the pump standing-wave pattern. Probing can be done using the same frequency and polarization as the pumping, in which case matching occurs at all heights. It can also be done with the opposing polarization at a different frequency, in which case matching only occurs over a narrow range of heights. The research results note that the advantage of the latter method is that probing and pumping can occur simultaneously, which is generally necessary in the E and F regions where the inhomogeneity decays rapidly.

The decay of the structuring is measured as a function of altitude and in the E and F regions is generally indicative of the ambipolar diffusion rate. Below that, turbulent mixing and photochemistry dominate. From the decay time constant, the electron density and temperature and the neutral density can be estimated. Research has shown that the measurement is straightforward, requires no true-height inversion, and it works in the valley region between the E and F region density maxima, as well as the

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

main E and F regions themselves. In the D region, electron number density can be measured, and complex photochemical and dynamical processes can be investigated.

Working at EISCAT (European Incoherent Scatter Scientific Association), Rietveld et al. (1996) also examined the Doppler shift of the API backscatter and tentatively associated it with the vertical neutral wind in the D and lower E regions. They reported small (few m/s), zero-mean winds with signs of gravity wave fluctuations. Many workshop participants agreed that this is a remarkable result that holds the promise of very accurate vertical wind measurements in daytime in over a range of altitudes not readily probed by other means. However, it was also noted that implementing the API technique at HAARP would require HF radar capability, either through the use of a collocated system or through the upgrade of HAARP itself.

Diffusion and Cooling Rates and E × B Drifts

In discussions at the workshop, it was noted that coherent radar scatter from induced plasma density irregularities provides another diagnostic of background parameters in the MLT and thermosphere. A signature feature of ionospheric-modification experiments is the generation of field-aligned plasma density irregularities (FAIs) (Hysell, 2008, p. 117). As noted in Hysell and Nossa (2009), “The irregularities are generated mainly by thermal parametric instabilities (Grach et al., 1978; Das and Fejer, 1979; Fejer, 1979; Kuo and Lee, 1982; Dysthe et al., 1983; Mjølhus, 1990) and, having entered nonlinear stages of development, by resonance instability (Vas’kov and Gurevich, 1977; Inhester et al., 1981; Grach et al., 1981; Dysthe et al., 1982; Lee and Kuo, 1983; Mjølhus, 1993)” (p. 2711). At the workshop, Herbert Carlson and others stated that these irregularities were interesting in their own right and because they also provide bright, regular targets of opportunity for study by coherent scatter radars. Most research has concentrated on F-region FAIs, although irregularities can be generated in the E region by pump waves with low enough frequency.

An example of coherent radar backscatter from E-region FAIs generated over the HAARP facility was provided by David Hysell and is shown in Figure 2.1. In this experiment, the heating pump power was ramped upward and then downward, allowing the determination of the threshold pump electric field required for initiation of thermal parametric instability. This threshold is a function of a number of parameters, including the inelastic electron cooling rate in the E region (Dysthe et al., 1983; Hysell et al., 2010). Because the altitude of the irregularities (where the heating frequency matches the local upper hybrid frequency) is well known, it is possible with this experiment to determine the electron cooling rate accurately as a function of altitude.

Whereas FAIs are created using O-mode heater emissions, research was reported at the workshop that found that simultaneous X-mode emissions can be used simply to heat the modified region. This facilitates tests of the temperature dependence of ionospheric relaxation processes. In the experiment described above (Miceli et. al.; see Figure 2.1), X-mode heating doubled the O-mode power required to generate FAIs. The doubling in this case can be attributed to enhanced absorption caused by heating the D region to approximately 2000 K. The increase in absorption is due both to the temperature dependence of the electron-neutral collision frequency and to changes in electron density arising from temperature-dependent D-region photochemistry. Both processes can be studied and quantified through ionospheric heating.

Moreover, Hysell pointed out that the diffusion rate of FAIs can be studied by monitoring how the coherent radar echoes decline in intensity after the heater is turned off. The decay timescale depends on the probe radar wavelength but is of the order of 100 ms for very-high-frequency (VHF) radars in the E region and a few seconds in the F region. Remarkably, the decay of the irregularities has been found to follow two power laws—one fast, and one slow (Hysell et al., 1996). The faster rate is consistent with ambipolar diffusion and consequently affords another estimate of the temperature, electron-neutral, and ion-neutral collision frequencies and composition at the ionospheric interaction height.

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

image

FIGURE 2.1 Range-time intensity plot of coherent echoes from heater-induced field-aligned irregularities over HAARP. The true range to the echoes is the apparent range (shown) plus 370 km. The echoes shown arose from altitudes close to 100 km. Both X- and O-mode emissions were used during the first interval whereas only O-mode emissions were used during the second. SOURCE: Adapted from: R.J. Miceli, D.L. Hysell, J. Munk, M. McCarrick, and J.D. Huba, Reexamining X-mode suppression and fine structure in artificial E region field-aligned plasma density irregularities, Radio Science 48:482-490, doi:10.1002/rds.20054, 2013. Available at http://onlinelibrary.wiley.com/doi/10.1002/rds.20054/full. Courtesy of D. Hysell.

In addition to the backscatter power, reported research found that the Doppler shift of the coherent echoes can also be measured during ionospheric modification experiments. Because the echoes have a much longer correlation time than incoherent scatter, the Doppler shifts can be measured far more accurately in a short time. In the F region, the Doppler shifts are indicative of E × B drifts. Heating experiments, consequently, afford extraordinarily accurate measurements of ionospheric electric fields using SuperDARN-class and similar radars, even where natural ionospheric irregularities are not present.

A workshop participant noted that as with airglow experiments, experiments involving coherent scatter benefit enormously from accurate knowledge of the heating interaction height. This information was said to be most gainfully provided by a collocated ISR.

Ionospheric Conductances

When micropulsations are present, the electric fields inferred from coherent radar scatter are indicative of the electric fields of the Alfvén waves that carry them. Such micropulsations are frequently observed over the Sura heater (Belenov et al., 1997). In what one participant described as a remarkable result, Sinitsin et al. (1999) measured the Doppler shifts of heater-induced FAIs over Sura at three different places along a single magnetic flux tube and found that the three signatures could not be accounted for by a single, shear Alfvén wave. Attributing the signatures to an incident shear wave, a reflected shear wave, and a reflected magnetosonic wave, they were able to infer the Pedersen and Hall conductances at the foot of the flux tube. The authors concluded that this unique experimental capability holds great promise for magnetosphere-ionosphere coupling studies because it has the potential to provide dynamic lower boundary conditions for magnetospheric models in real time.

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

Ionospheric Instabilities

It was noted repeatedly at the workshop that many important instabilities in the ionosphere can only be created by injecting a large amount of power, such as that available at HAARP. Further, although other instabilities occur naturally, some participants stated that they could be investigated more systematically than is otherwise generally possible using active experiments. An example of the latter kind is the Farley-Buneman instability, which occurs naturally under conditions of strong auroral forcing and creates waves that heat the electrons and modify the ionospheric conductivity. This instability is very sensitive to diffusion and collision rates and their temperature dependencies. Thus, some participants thought it could be possible to modify or even shut off the instability by increasing the E-region temperature with a heater like HAARP.

Another important heater-induced phenomenon is Langmuir turbulence, which has been investigated at Arecibo and EISCAT, where ISRs are available for diagnostics (Isham et al., 2012). As David Hysell explained, Langmuir turbulence enhances the plasma lines seen by ISRs above background levels through a variety of mechanisms, and understanding the effects offers insights into fundamental plasma physics, much in the same way that large colliders offer insights into fundamental particle physics. Langmuir turbulence also appears to generate suprathermal electrons, which cause much of the airglow seen during heating experiments (Djuth et al., 1999).

Making Waves

As noted at the workshop by Mike Taylor and others, the location of HAARP at a subauroral latitude is very interesting for studying the plasmasphere boundary layer and processes that lead to electromagnetic ion-cyclotron waves. At its location, they noted that HAARP can launch waves into this region and do stimulated experiments in radiation modification. It can also be used in studies involving highly elevated electron temperature, excited neutron gas, and the effects they produce, all of which would contribute to the understanding of the mechanisms that generate space weather in subauroral geospace.

Some participants claim that heaters could also potentially produce propagating responses in the ionosphere-thermosphere system, which could then be used to test sophisticated models of the ionosphere. Three-dimensional models have been used, for example, to describe how a localized disturbance at Arecibo would propagate in terms of ion acoustic waves, thermal pulse, density pulse, and so forth, all the way to the conjugate hemisphere, that could be detected by various instruments, especially ISR, at the conjugate point.

It was noted that many questions remain about the day-to-day variations in the ionosphere-thermosphere system and that there has been an increasing appreciation of the importance of “forcing from below,” thought to account for perhaps 20 to 30 percent of variability.2 Discussions among participants pointed to the use of heaters at other latitudes and HAARP to help understand how the complex system responds to such energy inputs. It was suggested that injecting energy into the ionosphere might also clarify the degree to which the ionosphere is involved in substorms and magnetospheric processes; for example, whether there are instabilities or other phenomena in the ionosphere that limit the electric fields or currents that can be carried in the magnetosphere-ionosphere system.

__________________

2 The importance of forcing from below was emphasized by the Panel on Atmosphere-Ionosphere-Magnetosphere Interactions, whose report to the decadal survey committee comprises Chapter 8 of the 2013 report Solar and Space Physics: A Science for a Technological Society (NRC, 2013).

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

Testing Models and Sensor Networks

Participants at the workshop considered how HF modification experiments could be used to provide quantitative parameter assessments for ionosphere-thermosphere models. One participant noted that measuring the response to a local heat input can validate the overall model behavior. Another participant observed that comprehensive study of the global coupled atmosphere will require distributed sensor networks (NRC, 2013), and it was asserted that HAARP could be used as a testbed to provide controlled perturbations for ground-based instrument development.

REFERENCES

Bakhmet’eva, N.V., and V.V.Belikovich. 2007. Modification of the Earth s ionosphere by high-power HF radio emission: Artificial periodic inhomogeneities and the sporadic E layer. Radiophysics and Quantum Electronics 50:633-644.

Belenov, A.F., L.M. Erukhimov, P.V. Ponomarenko, and Y.M. Yampolski. 1997. Interaction between artificial ionospheric turbulence and geomagnetic-pulsations. Journal of Atmospheric and Solar-Terrestrial Physics 59(18):2367-2372.

Belikovich, V.V., E.A. Benediktov, G.G. Getmantsev, Y.A. Ignat′ ev, and G.P. Komrako. 1975. Scattering of radio waves from the artificially perturbed F region. JETP Letters (English Translation) 22:243-244.

Bernhardt, P.A., N.A. Gondarenko, P.N. Guzdar, F.T. Djuth, C.A. Tepley, M.P. Sulzer, S.L. Ossakow, and D.L. Newman. 2003. Using radio-induced aurora to measure the horizontal structure of ion layers in the lower thermosphere. Journal of Geophysical Research 108(A9):1336, doi:10.1029/2002JA009,712.

Bernhardt, P.A., M. Wong, J.D. Huba, B.G. Fejer, L.S. Wagner, J.A. Goldstein, C.A. Selcher, V.L. Frolov, and E.N. Sergeev. 2012. Optical remote sensing of the thermosphere with HF pumped artificial airglow. Journal of Geophysical Research 105:10657-10671.

Das, A.C., and J.A. Fejer. 1979. Resonance instability of small-scale field-aligned irregularities. Journal of Geophysical Research 84:6701-6704.

Djuth, F.T., K.M. Groves, J.H. Elder, E.R. Shinn, J.M. Quinn, J. Villasenor, and A.Y. Wong. 1997. Measurements of artificial periodic inhomogeneities at HIPAS Observatory. Journal of Geophysical Research 102:24023-24035.

Djuth, F.T., P.A. Bernhardt, C.A. Tepley, J.A. Gardner, M.C. Kelley, A.L. Broadfoot, L.M. Kagan, M.P. Sulzer, J.H. Elder, C. Selcher, B. Isham, C. Brown, and H.C. Carlson. 1999. Large airglow enhancements produced via wave-plasma interactions in sporadic E. Geophysical Research Letters 26:1557-1560.

Dysthe, K., E. Mjølhus, H. P′ ecseli, and K. Rypdal. 1982. Thermal cavitons. Physica Scripta T 2:548-559.

Dysthe, K., E. Mjølhus, H. P′ ecseli, and K. Rypdal. 1983. A thermal oscillating two-stream instability. Physics of Fluids 26:146-157.

Fejer, J.A. 1979. Ionospheric modification and parametric instabilities. Reviews of Geophysics and Space Physics17:135-153.

Fejer, J.A., F.T. Djuth, and C.A. Gonzalez. 1984. Bragg backscatter from plasma inhomogenieties due to a powerful ionospherically reflected radio wave. Journal of Geophysical Research 89:9145.

Grach, S.M., A.N. Karashtin, N.A. Mityzkov, V.O. Rapoport, and V.Y. Trakhtengerts. 1978. Theory of thermal parametric instability in an inhomogenous plasma. Soviet Journal of Plasma Physics (English Translation) 4:737-741.

Grach, S., N. Mityakov, V. Rapoport, and V. Trakhtengertz. 1981. Thermal parametric turbulence in a plasma. Physica D 2:102-106.

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×

Gustavsson, B., T. Sergienko, M.T. Rietveld, F. Honary, A. Steen, B.U.E. Brändström, T.B. Leyser, A.L. Aruliah, T. Aso, M. Ejiri, and S. Marple. 2001. First tomographic estimate of volume distribution of HF-pump enhanced airglow emission. Journal of Geophysical Research 106:29105-29124.

Havnes, O. 2004. Polar Mesospheric Summer Echoes (PMSE) overshoot effect due to cycling of artificial electron heating. Journal of Geophysical Research 109:A02309, doi:10.1029/2003JA010159.

Havnes, O., C.L. Hoz, L.L. Naesheim, and M.T. Rietveld. 2003. First observations of the PMSE overshoot effect and its use for investigating the conditions in the summer mesosphere. Geophysical Research Letters 30:2229.

Hysell, D.L. 2008. 30MHz radar observations of artificial E region field-aligned plasma irregularities, Annales Geophysicae 26:117-129.

Hysell, D.L., and E. Nossa. 2009. Artificial E-region field-aligned plasma irregularities generated at pump frequencies near the second electron gyroharmonic. Annales Geophysicae 27:2711-2720.

Hysell, D.L., M.C. Kelley, Y.M. Yampolski, V.S. Beley, A.V. Koloskov, P.V. Ponomarenko, and O.F. Tyrnov. 1996. HF radar observations of decaying artificial field aligned irregularities. Journal of Geophysical Research 101:26981.

Hysell, D.L., E. Nossa, and M. McCarrick. 2010. Excitation threshold and gyroharmonic suppression of artificial E region field-aligned plasma density irregularities. Radio Science 45:RS6003, doi:10.1029/2010RS004360.

Inhester, B., A.C. Das, and J.A. Fejer. 1981. Generation of small-scale field-aligned irregularities in ionospheric heating experiments. Journal of Geophysical Research 86:9101-9105.

Isham, B., M.T. Rietveld, F.R.E. Forme, P. Guio, T. Grydeland, and E. Mjølhus. 2012. Cavitating Langmuir turbulence in the terrestrial aurora. Physical Review Letters 108:105003.

Kalogerakis, K.S., T.G. Slanger, E.A. Kendall, T.R. Pedersen, M.J. Kosch, B. Gustavsson, and M.T. Rietveld. 2009. Remote oxygen sensing by ionospheric excitation (ROSIE). Annales Geophysicae 27:2183-2189.

Kuo, S.P., and M.C. Lee. 1982. On the parametric excitation of plasma modes at upper hybrid resonance. Physics Letters A 91:444-446.

Lee, M.C., and S.P. Kuo. 1983. Excitation of upper hybrid waves by a thermal parametric instability. Journal of Plasma Physics 30:463-478.

Mahmoudian, A., W.A. Scales, M.J. Kosch, A. Senior, and M. Rietveld. 2011. Dusty space plasma diagnosis using temporal behavior of polar mesospheric summer echoes during active modification. Annales Geophysicae 29:2169-2179.

Miceli, R.J., D.L. Hysell, J. Munk, M. McCarrick, and J.D. Huba. 2013. Reexamining X-mode suppression and fine structure in artificial E-region field-aligned plasma density irregularities. Radio Science 48:482-490, doi:10.1002/rds.20054.

Mjølhus, E. 1990. On linear conversion in magnetized plasmas. Radio Science 6:1321-1339.

Mjølhus, E. 1993. On the small scale striation effect in ionospheric modification experiments near harmonics of the electron gyro frequency. Journal of Atmospheric and Solar-Terrestrial Physics 55(6):907-918.

NRC (National Research Council). 2013. Solar and Space Physics: A Science for a Technological Society. The National Academies Press, Washington, D.C.

Pedersen, T., B. Gustavsson, E. Mishin, E. Kendall, T. Mills, H.C. Carlson, and A.L. Snyder. 2010. Creation of artificial ionospheric layers using high-power HF waves. Geophysical Research Letters 37:L02106, doi:10.1029/2009GL041895.

Rietveld, M.T., E. Turunen, H. Matveinen, N.P. Goncharov, and P. Pollar. 1996. Artificial periodic irregularities in the auroral ionosphere. Annales Geophysicae 14:1437-1453.

Sinitsin, V.G., M.C. Kelley, Y.M. Yampolski, D.L. Hysell, and A.V. Zalizovski. 1999. Ionospheric conductivities according to Doppler radar observations of stimulated turbulence. Journal of Atmospheric and Solar-Terrestrial Physics 61(12):903-912.

Vas’kov, V.V., and A.V. Gurevich. 1977. Resonance instability of smallscale plasma perturbations. Soviet Physics, JEPT (English Translation) 46:487-494.

Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 21
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 22
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 23
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 24
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 25
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 26
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 27
Suggested Citation:"2 Mesosphere, Thermosphere, and Ionosphere." National Research Council. 2014. Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/18620.
×
Page 28
Next: 3 Magnetospheric Physics »
Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research: Report of a Workshop Get This Book
×
Buy Paperback | $39.00 Buy Ebook | $31.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research is the summary of a workshop convened by the Space Studies Board of the National Research Council in May 2013. The request for this workshop was informed by the sponsors' awareness of the possibility that tight budgets would result in the Department of Defense's curtailment or even termination1 of support for the High Frequency Active Auroral Research Program (HAARP), which includes the world's highest-power and most capable high-frequency transmitter - "heater" - for ionospheric research. Although the workshop was organized to consider the utility of heaters in upper atmospheric research in general, it had a specific focus on the HAARP transmitter facility, which is located in a remote part of southeastern Alaska.

Research conducted by the ionospheric modifications community - a community that uses high-frequency transmitters to inject energy in the ionosphere and measure its effects using ground and space-based diagnostics - is focused on understanding the interaction of radio waves with the ionospheric plasma, the local consequences of heating in the ionosphere, and studies of non-linear plasma physics processes. The workshop provided a forum for information exchange between the comparatively small group of scientists engaged in programs of upper atmospheric research using high-power high-frequency radar transmitters and the larger ionospherethermosphere-magnetosphere research community.

This report examines the state of the art in active ionospheric and thermospheric research; considers the fundamental research areas in ionospheric science that can be addressed using high-power high-frequency-band transmitters; discusses emerging science questions that might benefit from active ionospheric experiments in the sub-auroral zone; and considers ways to combine similar facilities to perform global ionospheric science. The report also examines research opportunities that might arise from the relocation of the AMISR incoherent scatter radar from the Poker Flat Research Facility in Poker Flat, AK to Gakona, AK, the location of the HAARP facility.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!