SA31A-1105 0800h
Initial Results Of The Lower Thermospheric Vertical Wind Estimated With Incoherent-Scatter Radars At High Latitudes
We will present some recent results of the lower thermospheric vertical wind derived with incoherent-scatter (IS) radars at high latitudes. The coupled mesosphere-thermosphere-ionosphere system at high latitudes exhibits complicated temporal and spatial variations in association with the energy coupling between upper and lower regions. While our knowledge of this system has been extended during the last three decades, there remain various interesting phenomena in that region; one of them is the vertical motion in the lower thermosphere (from 90 to 130 km).A limited number of researchers have reported lower thermospheric vertical winds observed with Fabry Perot Interferometer (FPI, 557.7nm) and IS radar. Those results indicate that there is an unexpected level of small-scale structure in the polar thermospheric dynamics often with remarkably large amplitudes. These winds pose various important questions concerning, for example, the momentum transfer in association with atmospheric wave breaking, effects of the thermospheric constituent mixture on chemical reactions, and the energy budget as a part of the magnetosphere-ionosphere-thermosphere coupled system. Our understanding on the lower thermospheric vertical motions is inadequate to consistently explain the experimental data. IS radar data is available to calculate the neutral velocity through the steady state ion momentum equation neglecting ambipolar diffusion. This method has been applied by many other researchers to derive the horizontal component of the neutral wind during the last three decades. However, the conventional IS measurement method should not be applied simply to derivation of the vertical component because the method is subject to significantly large errors, which frequently exceed the calculated vertical neutral speeds. Furthermore, some beam configurations necessarily assume no vertical neutral winds. In this presentation, new radar beam configurations suitable for the vertical neutral wind estimation are introduced, and show some recent results using the new configuration applied to the Sondrestrom IS radar. This method can be applied to the Advanced Modular IS radar (AMISR), which will be planned for Poker Flat, Alaska, in near future. Some features of interest are large vertical shears in the vertical neutral wind below 120 km, and temporal variations with large amplitudes in excess of a few tens m/s.
SA31A-1106 0800h
Recent Incoherent Scatter Radar Experiments and Results at Arecibo
In this paper we describe recent experiments and techniques that push the boundary in terms of the information that can be extracted from the incoherent scatter (IS) spectrum, as well as an application of the Arecibo dual-beam system. One particular problem of the IS radar technique since its beginning has been measuring unambiguously the electron and ion temperature (Te and Ti) plus the molecular ion fraction in the F1 region during the day when Te is greater than Ti. So far, pretty much all IS radars make some assumptions in order to routinely process IS autocorrelation functions to get at least some values for temperatures or ion composition. In this paper we show one solution to this problem, which is based in the combination of plasma line and ion line portions of the IS spectrum to obtain unambiguous Te, Ti and molecular ion fraction during the day. During the nighttime, we cannot measure the plasma line and the F1 region is pretty much gone, but layers typically form at Arecibo in the E region ionosphere. Some of these layers can be very narrow in height and contain metallic ions, and we have in recent times performed spectral measurements with a very high altitude resolution (75 meters), to determine the ion composition within these thin layers. Another interesting recent result that we will discuss is related to the observations of photoelectron enhancement of the incoherent scatter gyrolines at dawn. These new observations at Arecibo confirm the photoelectron enhancement effect of the gyrolines previously observed by the EISCAT VHF radar. Finally, we will show a big improvement in the time resolution of Arecibo ion vector velocity measurements. Until recently, vector velocity measurements (2D or 3D) could only be done by physically rotating the antenna beam to point into different directions, but now we can take advantage of the dual-beam system to determine instantaneously the eastward electric field and the meridional neutral wind velocity in the F region with a time resolution of about one minute.
SA31A-1107 0800h
Inversion Algorithm for Auroral Emissions due to an e-Beam From an Electrically Floating Bare Tether
A (bare) conductive tether electrically floating in LEO orbit would be an effective e-beam source free of problems that marred standard beams producing artificial auroras. Ambient ions impacting the tether with KeV energies over most of its length liberate secondary electrons that result in emissions in the E-layer. Brightness measurements from the spacecraft for line-of-sight integrated emissions might allow determination of the (neutral) density vertical profile in that critical layer; mixed effects from the variation of beam flux and energy along the tether, and neutral density dependence on altitude, lead to a brightness peak in the beam footprint at the E-layer. Tomographic inversion to determine the density profile is made difficult by beam-broadening in elastic collisions, which tends to flatten the peak, and by the highly-nonlinear dependence of line-of-sight brightness on the density profile. A new inversion algorithm is here presented. The low densities prevailing near the tether, in the F-layer, allow neglecting the energy lost by the electrons down to some altitude. An average density in that region can be estimated using brightness of lines-of-sight farther from the magnetic dip angle. Tomographic inversion then proceeds forwards using brightness of subsequent lines of sight to get density values downwards. Brightness values for lines-of-sight closer to the dip angle allow algorithm iteration. Results for round-wire tethers and tape tethers are compared.
SA31A-1108 0800h
Vehicle Charging on the 29.036 and 29.037 Rockets of the EQUIS II Campaign.
The rocket investigation "Scattering Layer in the Bottomside Equatorial F-region Ionosphere", was part of the NASA EQUIS II campaign. Two salvos of sounding rockets were launched from Roi Namur in Kwajalein on August 7th and 15th of 2004. The project's mission was to investigate the thin scattering layers in the post sunset equatorial F region ionosphere that act as precursors to a fully developed equatorial spread F. Each of the salvos consisted of one instrumented and two chemical release payloads. The instrumented rockets were launched westward into equatorial spread F precursor that was first observed from ground using the Altair radar. The instrumented rockets reached an apogee of ~450 km. The instruments consisted of a Sweeping Langmuir Probe (SLP), a fixed bias DC Probe (DCP), a Plasma Impedance Probe consisting of a Plasma Frequency Probe and a Plasma Sweeping Probe built at Utah State University. The instrument suite also included an Electric Field Probe built by Penn State University. This poster presents observations of vehicle charging and preliminary data from the SLP and DCP.
SA31A-1109 0800h
In-Situ Measurements of Atomic Oxygen in the MLT Region: The ATOX Resonance Fluorescence/Absorption sensor
The Utah State University Atomic Oxygen sensor (ATOX) was launched aboard the Coupling of Dynamics and Aurora (CODA) payloads on January 22, 1999 from Poker Flat, Alaska and again on February 21, 2001, both into diffuse auroras. Atomic oxygen profiles were measured in-situ by a combination of resonance and florescence techniques. While a comparison of the data reveals significant structural differences between the two flights, a deeper investigation provides some insight into the inherent obstacles from which the resonant fluorescent/absorption technique suffers. Density flow field disturbances from the rocket motion shock effect and spin stabilization, Doppler shifts, fluctuations in lamp output, and variations in photometer sensitivity due to temperature change and contamination seem to be the primary contributors. Analysis shows that most if not all of these obstacles contribute to the degraded accuracy of the collected data. A comparison of each data set with atmospheric models and previously made measurements show good agreement on a large scale, a deeper investigation into its design and operation suggests modifications to the sensor and the data analysis technique may produce data with much higher accuracies.
SA31A-1110 0800h
Multi-year High Latitude Mesospheric Neutral Wind Observations Using a Fabry-Perot Interferometer
From 1995 to 1999, a Fabry-Perot Interferometer (FPI) was stationed at Resolute Bay, Canada (75N, 95W) to measure the mesospheric neutral winds in the polar cap from the OH nightglow emission during winter seasons. A 12-hour wave is the most prominent feature in the neutral winds. The wave amplitude has large day-to-day variations and inter-annual variability, whereas the phase of the wave appears to be largely consistent. Small phase shift from early winter to later winter was noticed during most of the seasons when early winter data were available. The 12-hour wave showed stronger variability during the 1995/1996 winter season, which may be related to the non-linear interaction with planetary waves. Large negative zonal winds were observed during stratospheric sudden warming events.
SA31A-1111 0800h
Characteristics of the mesospheric layers observed using resonance lidars from Arecibo
The resonance lidar at the Arecibo Observatory has been used for simultaneous observations of Na and Fe metallic layers. Such measurements are extremely useful for studying the characteristics of the sporadic layers, which are the regions of enhanced atomic densities as compared to the background layer. Na being alkali like metal behaves very differently from the heavy metal and so the coincident measurements can provide better insight about the two metallic layers. Earlier observations of the annual variation of the Fe metallic layer have revealed the latitudinal variations of the various parameters of the Fe layer at a low latitude station like Arecibo are very different from that observed from a mid latitude site. This paper will present some interesting simultaneous measurements of the Na and Fe layer from Arecibo made in February and March, 2004. On the night of 18 March 2004, we observed `C' type sporadic Na layers (Na$_{S}$) between 92 to 98 km altitude regions. This event occurred around 22:30 hours lasting for about one hour. This was followed by two more events that were less intensive than the first one with a half hour interval between them. However, there is an indication of very weak layers in the case of the Fe during such strong Na$_{S}$. This appears to be very different from the sporadic activity observed at high latitudes where the occurrence frequency for Fe$_{S}$ is more than that observed in the case of Na. This will be compared with the sporadic E layers.
SA31A-1112 0800h
Rayleigh-Lidar Observations of Mesospheric Mid-latitude Density Climatology Above Utah State University
Lidars have been used extensively to derive temperatures, but not absolute densities, in the mesospheric region of the atmosphere. We used observations since 1993 with the Rayleigh-scatter lidar at the Atmospheric Lidar Observatory (ALO) at Utah State University ($41.7\deg$N, $111.8\deg$W) to create an absolute density climatology between 45 and $\sim$95 km. The observations provide profiles of relative density to which an absolute scale is attached by normalizing the profiles at 45 km to the densities in the MSISe00 empirical model. We examine the density variations during the climatological year and from year to year. For instance, the annual density variation at 75 km is $\sim$60$%$ with a maximum in June and a minimum in early spring. The absolute densities are also compared with the MSISe00 model and are found to deviate by as much as 25$%$.
SA31A-1113 0800h
Mesospheric Inversion Layers above Utah State University
A 10-year, mesospheric temperature climatology was produced using the Rayleigh-scatter lidar at the Atmospheric Lidar Observatory at Utah State University. Each of approximately 600 nights in this mid-latitude (41.7$\deg$N, 111.8$\deg$W) climatology was examined for mesospheric inversion layers (MILs). Many of the MIL findings, in particular, the seasonal change in altitude, amplitude, and probability of occurrence are similar to those found at other mid-latitude locations. However, this detailed MIL analysis found several new results including a high probability of multiple inversions for a single profile, an increase in MIL amplitude with altitude, and little seasonal variation for large amplitude MILs.
SA31A-1114 0800h
Investigation of Dynamical Structures with OSIRIS on Odin
Limb measurements made with the OSIRIS infrared imager on the Odin satellite provide extensive proxy measurements of mesospheric ozone through observations of the Oxygen Infrared Atmospheric bands. Dynamical structures in mesospheric ozone bearing tidal signatures have been observed, and are the subject of this study. This work presents an analysis of the spatial distributions, time scales, and wavenumber modes of these structures.
SA31A-1115 0800h
Application of Electromagnetic Wave-Ionospheric Interactions to Global Warming in the Arctic Region
An approach to expel pollutants which can contribute to global warming from the upper atmosphere by the use of HF electromagnetic waves has been proposed [1]. Laboratory plasma experiments have shown significant gyro-resonance acceleration of minority ion species in a plasma is possible. The separation of ions differing in mass by one unit has been achieved. This method is applicable to the acceleration of selective ions perpendicular to the geomagnetic field in the ionosphere and involves the modulation of the auroral electrojet current to excite ion cyclotron waves. On account of the divergent geomagnetic field in the polar atmosphere the accelerated perpendicular ion velocity is converted into an upward motion along open magnetic field lines. The ions thus removed will not return to the upper atmosphere. Negatively charged particles move upward by the fair-weather electric field and by atmospheric convection. When these ions reach above 120 km altitude where the ion gyro frequency is comparable to or greater than the ion-neutral collision frequency, they can be accelerated by EM fields through the gyro resonance interaction. By modulating the auroral electrojet in the gyro frequency range for important minority ion species, ion cyclotron waves can be excited which propagate nearly along the magnetic field lines. Experimental evidence for this effect has been obtained with the HIPAS facility [1]. By exciting ELF waves over a range of ion gyro frequencies of dominant ion species, dips were observed in the magnetometer data at these frequencies. This suggests the ELF wave energy was absorbed by the ion species. Similar ion acceleration and expelling phenomenon over the polar regions occurs naturally in so called ion conics as observed by high latitude satellites. Field aligned currents might provide free energy needed to make this process practical. Field experiments are designed to observe directly this selective ion acceleration using the HIPAS Lidar together with ground-based and space-borne detectors. 1. Wong, A.Y. et al. AIP CIP 96-27719, Chap 3, pp 41-75, 1997
SA31A-1116 0800h
Short range VLF sky wave observations of lightning-induced ionospheric effects
At locations close (~100-km) to a VLF transmitter, observation of the sky wave signal from the transmitter is possible by aligning a proximate magnetic loop antenna to null the ground signal. Previous observations using this arrangement [e.g., Rodriguez et al. 1992], and [Pasko et al., 2002] show a very high degree of temporal variability in received signal amplitude. Consideration of Early/Fast and Lightning-induced Electron Precipitation (LEP) events under these constraints show an unusual number of remarkably large events. For example, we have observed Early/Fast events with positive amplitude changes up to ~8 dB and negative amplitude changes as high as ~19 dB. In addition we have observed possible LEP events with positive amplitude changes of ~5 dB and onset duration of 15 seconds. The recovery signatures of these events are also very unusual, often with non-exponential recovery, or no recovery at all. Combining the data from previous campaigns with a recent data set (August 2004) of observations at Arecibo, Puerto Rico we analyze three separate instances in which a magnetic loop antenna is deployed with the intent of observing the sky wave. In this paper we report the results of the analysis of this data to quantitatively determine whether the anomalous nature of these findings is primarily due to the high inherent variability of the observed amplitude signal or the close proximity of the receiver to the disturbed ionospheric region, which must necessarily be nearly overhead the receiver and/or transmitter.
SA31A-1117 0800h
Lidar-derived, long-term trends and variability in the mid-latitude middle atmosphere
The USU Rayleigh Lidar (41.74$\deg$N 111.81$\deg$W) data set spans more than ten years, containing 593 nightly profiles from September 1993 to the present. A least-squares method was used to fit a model to the data to determine a linear trend, the amplitude and phase of the annual and semiannual variations, and solar cycle effects. A large cooling trend of about 1K/year was observed at 80 km, while there was no statistically significant trend below 65 km. The annual variation closely matched the MSISe90 model in magnitude and phase, while the semiannual variation is close in magnitude only. A residual resampling technique was used to determine the error bars for the amplitudes and phase angles. An 80-day, smoothed, MgII index was used for the solar proxy. It gave better results than the F10.7 index. The solar-cycle effect from 68 to 72 km was -5.32 K/Cycle, which was statistically significant at the 95$%$ level. No other statistically significant solar-cycle effect was found.
SA31A-1118 0800h
Calibration of the Plasma Impedance Probe for the EQUIS II Sounding Rocket Campaign.
Two Plasma Impedance Probes (PIP) made nighttime measurements of the low latitude ionosphere as part of the EQUIS II sounding rocket campaign. The rockets were launched from Kwajalein on August 7th and 15th and reached 450 km in altitude. These probes operate by sensing the input impedance of an antenna immersed in the ionospheric plasma. Each probe made measurements using two different antenna geometries, a traditional monopole antenna and a patch antenna located on the rocket surface. There are several analytic theories for the impedance of monopole or dipole antenna in a space plasma. There are no analytic theories for a patch antenna. Utah State has developed a Plasma Fluid Finite Difference Time Domain (PF-FDTD) simulation that can be used to model various antenna geometries. Antenna impedance data from both geometries are presented and compared with analytic and the PF-FDTD simulation. Preliminary results of the extraction of electron density, electron neutral collision frequency, and electron temperature along the rocket trajectory are presented.
SA31A-1119 0800h
Absolute Intensity Calibration of Atmospheric Spectra Through Spectrophotometric Standard Stars
Astronomers use certain bright stars, known as spectrophotometric standard stars, as standard candles from which to calibrate their instrumental intensity responses [\textit{Oke, 1990}, \textit{Hamuy et al.,1994}]. These response curves can then be used to intensity calibrate their object images and spectra in absolute units. Spectrophotometric standard stars are being used to intensity calibrate our archived high-resolution astronomical spectra of the night sky, so as to increase their utility for aeronomic research. There are several fairly bright spectrophotometric standards which together provide a calibration source that can be accessed and referenced to on a night to night basis. We discuss here the advantages and difficulties in using spectrophotmetric standard stars for calibration, the techniques that are employed by us and astronomers to calibrate high resolution astronomical spectra, and these techniques' general applicability to atmospheric observations. This work was supported by NASA Applied Information Systems Research and NSF Aeronomy. Hamuy, M., N.B. Suntzeff, S.R. Heathcote, A.R. Walker, P. Gigoux, and M.M. Phillips, Southern Spectrophotometric Standards, 2, \textit{Pub. Astron. Soc. Pac., 106}, 566--589, 1994 Oke, J.B., Faint Spectrophotometric Standard Stars, \textit{Astron. J., 99}, 1621--1631, 1990
SA31A-1120 0800h
Polar Ground-Based Measurements of Mesospheric Carbon Monoxide
Carbon monoxide has often been studied as an important tracer of the dynamics of the middle and upper atmosphere, since its density depends heavily on the details of atmospheric chemistry and transport processes. The mesospheric region, difficult to measure with most remote sensing techniques, is of particular interest due to its role as a boundary between the neutral lower atmosphere and the highly charged upper atmosphere. Measuring atmospheric dynamics from the earth's rotational pole makes it possible to collect especially interesting results because many effects due to the earth';s rotation are minimized. In the past, most continuous measurements of atmospheric CO have been obtained by mid-latitude ground observations of the $J = 1 \rightarrow 0$ transition and more recently, by satellite measurements. Additionally, meteor radars and measurements of the aurora by optical telescopes have been used in studies of the thermosphere above about 80 km. The Antarctic Sub-millimeter Telescope/Remote Observatory (AST/RO) is capable of observing rotational emissions of CO at a broad range of altitudes in the upper mesosphere and lower thermosphere, between about 40 and 130 km. Due to the dry climate at the South Pole, it is possible to obtain higher frequency measurements with little interference from water vapor. By measuring the $J = 2 \rightarrow1$, $J =4 \rightarrow 3$, and $J = 7 \rightarrow 6$ rotational transitions of CO, AST/RO can observe processes in the mesosphere with greater accuracy than previous studies have obtained. First results using this technique have already produced mesospheric wind velocity data and density and mixing profile results. Additional analysis of the reduced data from these observations will be presented.
SA31A-1121 0800h
Hydroxyl and Atomic Oxygen Airglow Response to Short-Period Gravity Waves Undergoing Vertical Reflection
During the ALOHA93 campaign, a short period (4.4 minute) gravity wave was observed to perturb the hydroxyl (OH NIR) and atomic oxygen (OI 557.7 nm) airglow layers such that the intensities of the perturbed emissions were 180 degrees out of phase [Taylor et al., GRL, 22, 2849, 1995]. Explanations for this phenomena have been presented in terms of dynamic phase reversals associated with complex ducted wave structure [Munasinghe et al., JGR, 103(D6), 6467, 1998] or a mesospheric bore [Dewan and Picard, JGR, 103(D6), 6295, 1998]. We here demonstrate, in general form, that airglow chemistry alone may explain such phase variations between OH and OI emissions. The lower-thermosphere forms a stable ducting region for short-period atmospheric gravity waves. These waves may be excited by tropospheric convective sources through linear and nonlinear mechanisms [Walterscheid et al., JGR, 106, 31825, 2001; Snively and Pasko, GRL, 30(24), 2254, doi:10.1029/2003GL018436, 2003]. For waves with very short periods, near 5 minutes, the lower boundary of the lower-thermospheric duct is typically located at mesopause. This altitude also coincides with several commonly-measured airglow layers, including the OH and OI emissions. Thus, short-period ducted gravity waves propagating in the lower thermosphere may be reflected in the region of the airglow layers. Waves undergoing reflection exhibit very long vertical wavelengths; phase fronts of these waves may easily penetrate multiple airglow layers simultaneously with no significant vertical dynamic phase variations. Using a two-dimensional, fully-nonlinear model describing wave dynamics and OH and OI airglow chemistry, we examine the airglow response due to short-period gravity waves undergoing vertical reflection. Numerical model results are compared with a simplified analytical model. Due to time dependence of chemical reactions, we find that significant phase differences between the OH and OI airglow emissions may arise. This effect is discussed and compared with observations depicting anti-phase OH and OI emissions associated with short-period gravity wave motions [e.g., Taylor et al., 1995]
SA31A-1122 0800h
Multi-layer gravity wave reconstruction from multi-sensor spectroscopic airglow imaging
The extraction of gravity wave vertical profiles in the airglow layers is critical in studying wave propagation and wave breaking effects on the energy and thermal balance of the mesosphere and lower thermosphere (MLT) region. In this work, multi-sensor airglow imaging is explored in a common-volume observation configuration to reconstruct horizontal/vertical cross-sections of mesospheric wave structures by tomographic inversion. A forward model is constructed mapping the photometric brightness measurements from multiple sensors to height-dependent volume emission rates of relevant spectroscopic processes. Simulations are then performed to quantify the ability to resolve gravity wave structures from multiple airglow layers (OH, Na, O2, and O) at different signal to noise ratios with the goal of designing geometric baseline for imaging systems. The error in the reconstruction is used as a guideline for optimizing modeling of observations needed to recover horizontal/vertical gravity wave structure with different parameters including tilt angle, wavelength, and perturbation strength. Such modeling investigations provide valuable insight toward the optimal design of experiments aimed at resolving gravity wave structures in airglow layers.
SA31A-1123 0800h
Determination of high-altitude atomic oxygen density and temperature by a Raman LIDAR
It is shown that a Raman LIDAR (Light Detection And Ranging) has the potential of determining the densities of each of the three fine structure levels of the ground state of atomic oxygen. Since it was established earlier that the fine structure levels are in local thermodynamic equilibrium (LTE) up to at least 350 km altitude, the Raman LIDAR therefore also has the potential of determining the up to that altitude. Since a LIDAR can be gated as well as pointed in different directions, it has the potential of giving three dimensional maps of the density of atomic oxygen and temperature.
SA31A-1124 0800h
Arctic Strato-Mesospheric Temperature and Wind Variations
Upper stratosphere and mesosphere rocket measurements are actively used to investigate interaction between the neutral, electrical, and chemical atmospheres and between lower and upper layers of these regions. Satellite temperature measurements from HALOE and from inflatable falling spheres complement each other and allow illustrations of the annual cycle to 85 km altitude. Falling sphere wind and temperature measurements reveal variability that differs as a function of altitude, location, and time. We discuss the state of the Arctic atmosphere during the summer 2002 (Andoya, Norway) and winter 2003 (ESRANGE, Sweden) campaigns of MaCWAVE. Balloon-borne profiles to 30 km altitude and sphere profiles between 50 and 90 km show unique small-scale structure. Nonetheless, there are practical implications that additional measurements are very much needed to complete the full vertical profile picture. Our discussion concentrates on the distribution of temperature and wind and their variability. However, reliable measurements from other high latitude NASA programs over a number of years are available to help properly calculate mean values and the distribution of the individual measurements. Since the available rocket data in the Arctic's upper atmosphere are sparse the results we present are basically a snapshot of atmospheric structure.
SA31A-1125 0800h
Investigation of a `Wall' Wave Event Using Airglow and Na Wind/Temperature Lidar Measurements
A `wall' wave was observed on August 12, 2004 at Maui, HI ($20.7\deg$N, $156.3\deg$W) by an all-sky OH airglow imager. The `wall' wave emerged from the SW horizon at $\sim$ 0800 UT. It propagated toward the NE, passed the zenith at $\sim$ 0900 UT, and disappeared at $\sim$ 1200 UT. The brightness of the OH airglow in the whole sky increased by about 100% during the passage of the `wall' wave. Small-scale high-frequency gravity waves were observed to be phase-locked with the `wall' wave. The dynamical effects of the `wall' wave are investigated using simultaneous temperature and wind measurements made by a Na lidar system, and wind observations made with a meteor radar. It is found the sharp increase of the zenith airglow intensity is accompanied by a rapid increase of temperature of $\sim$ 60 K in 30 min in the 90-95 km range. The tidal structures in the horizontal winds were significantly changed during the time the `wall' wave was observed. The phases of the diurnal tidal winds were lagged by 4-5 hours comparing with the day before (August 11, 2004). The underlying mechanisms for these observed features are explored.
SA31A-1126 0800h
Potential distribution around sounding rockets in mesospheric layers with charged aerosol particles
It is shown that large potential variations can exist inside the wake of sounding rockets moving with supersonic velocity through the summertime mesopause region. The potential distribution is driven by charge separation induced by the shock wave of the rocket. The low conductivity conditions due to the attachment of free electrons to aerosol particles allow large electric fields, of the order of V/m, to be maintained. The numerical results from a simple model are consistent with recent electric field measurements carried out by the DROPPS-1 sounding rocket.