Thermospheric Mass Density Research Articles

A method to predict thermospheric mass density response to geomagnetic disturbances using time‐integrated auroral electrojet index

AbstractUsing the thermospheric mass density measurements from the European Space Agency's Gravity field and steady state Ocean Circulation Explorer (GOCE) satellite, we develop a new empirical geomagnetic disturbance time correction based on integrating the auroral electrojet (AE) index. For this, a US Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar (NRLMSISE‐00) model with no geomagnetic parametrization is subtracted from the GOCE densities, and the regressions between the time‐integrated AE index and density residuals are computed as a function of latitude, solar time, and day of year. When we add this correction to the quiet time reference NRLMSISE‐00 model, it increases the model's disturbance time correlation with the 270 km normalized GOCE densities from 0.71 to 0.86. We assess the effect of integrating thermospheric density proxies with respect to time using both geomagnetic and solar indices and discover that the integration of AE, ap, and the epsilon parameter significantly increase their correlation with the orbit‐averaged GOCE densities. We compare the predictions of our empirical correction with the NRLMSISE‐00 and Jacchia‐Bowman (JB2008) models, and significant deviations from the measurements are discovered. The NRLMSISE‐00 is confirmed to generally underestimate the density enhancement, and the latitudinal shape of the predicted response shows too low enhancements at middle latitudes. Even though these are not issues for the JB2008 model, it performs weaker than the NRLMSISE‐00 at reproducing the orbit‐averaged densities. This unexpected result is attributed to the weakness of the ap parametrization, which is used in the model during smaller disturbances.

Pathways of F region thermospheric mass density enhancement via soft electron precipitation

AbstractThe efficiencies of pathways of thermospheric heating via soft electron precipitation in the dayside cusp region are investigated using the coupled magnetosphere‐ionosphere‐thermosphere model (CMIT). Event‐based data‐model comparisons show that the CMIT model is capable of reproducing the thermospheric mass density variations measured by the CHAMP satellite during both quite and active periods. During the 24 August 2005 storm event (Kp = 6−) while intense Joule heating rate occurs in the polar cusp region, including soft electron precipitation is important for accurately modeling the F region thermospheric mass density distribution near the cusp region. During the 27 July 2007 event (Kp = 2−) while little Joule heating rate occurs in the polar cusp region, the controlled CMIT simulations suggest that the direct pathway through the energy exchange between soft electrons and thermospheric neutrals is the dominant process during this event, which only has a small effect on the neutral temperature and mass density at 400 km altitude. Comparisons between the two case studies show that the indirect pathway via increasing the F region Joule heating rate is a dominant process during the 24 August 2005 storm event, which is much more efficient than the direct heating process.

Statistical analysis of thermospheric density response to solar wind sector structure

AbstractThe global averaged thermospheric mass density data during 1967–2007 are analyzed to investigate thermospheric response to solar wind sector structure. Well‐defined solar wind sectors have polarities of interplanetary magnetic field (IMF) toward (+Bx, −By) or away (−Bx, +By) from the Sun for multiple days. In March, thermospheric mass densities increase from the away to toward polarities, with a maximum density perturbation of ~23% at 400 km with respect to the 11 day averages; they decline from the toward to away polarities, and the maximum reduction at 400 km can reach 12%, which is associated with a weakened heating effect of the geomagnetic activity. In September, thermospheric densities respond in an opposite way to the same sector structure as compared with the March results. In solstice seasons, thermospheric density variations in response to solar wind sector structure are typically smaller than 10% relative to the 11 day averages. Besides the seasonal dependence, relative density changes tend to become greater at higher altitude and lower solar activity. However, during solar minimum the density variations at 550 km are not substantially larger than those at 400 km due to the possible descending of the transition altitude between helium and atomic oxygen. Moreover, the corotating interaction region (CIR) has a high probability to occur around the sector boundary. Consequently, the CIR effects account for one third of the density enhancement at 400 km during ineffective‐effective sectors, whereas the density reduction associated with effective‐ineffective sectors can be impaired by about 50%, which is independent of altitude.

Altitude and solar activity dependence of 1967–2005 thermospheric density trends derived from orbital drag

AbstractWe examine 1967–2005 thermospheric mass density trends (as well as 1967–2013 trends) derived from satellite orbit data, as a function of altitude, solar flux, and geomagnetic activity. At 400 km altitude, the estimated 1967–2005 trend is −2.0 ± 0.5% per decade. The estimated trends become increasingly negative with increasing height between 250 and 575 km, suggesting an exospheric temperature trend of −1 to −2 K per decade, which is much smaller than temperature trends that have been inferred from ground‐based incoherent scatter radar measurements. The orbit‐derived trend height profiles are in good agreement with model simulations of the enhanced cooling that results from increasing concentration of CO2 in the mesosphere and lower thermosphere. In contrast to earlier results, the solar flux dependence of the estimated trends is weak, relative to the trend uncertainty. There is some indication that the trends may be stronger during very low geomagnetic activity conditions. Estimation of the solar flux and geomagnetic activity dependence of the trends is complicated by monotonic decreases in these drivers over the past four solar minima together with the CO2 increase, all of which drive interminima decreases in density.

Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Abstract. By using the accelerometer measurements from CHAMP and GRACE satellites, the tidal signatures of the thermospheric mass density and zonal wind at midlatitudes have been analyzed in this study. The results show that the mass density and zonal wind at southern midlatitudes are dominated by a longitudinal wave-1 pattern. The most prominent tidal components in mass density and zonal wind are the diurnal tides D0 and DW2 and the semidiurnal tides SW1 and SW3. This is consistent with the tidal signatures in the F region electron density at midlatitudes as reported by Xiong and Lühr (2014). These same tidal components are observed both in the thermospheric and ionospheric quantities, supporting a mechanism that the non-migrating tides in the upper atmosphere are excited in situ by ion–neutral interactions at midlatitudes, consistent with the modeling results of Jones Jr. et al. (2013). We regard the thermospheric dynamics as the main driver for the electron density tidal structures. An example is the in-phase variation of D0 between electron density and mass density in both hemispheres. Further research including coupled atmospheric models is probably needed for explaining the similarities and differences between thermospheric and ionospheric tidal signals at midlatitudes.

Correction of the photoelectron heating efficiency within the global ionosphere‐thermosphere model using Retrospective Cost Model Refinement

Many physics-based models are used to study and monitor the terrestrial upper atmosphere. Each of these models has internal parameterizations that introduce bias if they are not tuned for a specific set of run conditions. This study uses Retrospective Cost Model Refinement (RCMR) to remove internal model bias in the Global Ionosphere Thermosphere Model (GITM) through parameter estimation. RCMR is a low-cost method that uses the error between truth data and a biased estimate to improve the biased model. Neutral mass density measurements are used to estimate an appropriate photoelectron heating efficiency, which is shown to drive the modeled thermosphere closer to the real thermosphere. Observations from the Challenging Mini-Payload (CHAMP) satellite taken under active and quiet solar conditions show that RCMR successfully drives the GITM thermospheric mass density to the observed values, removing model bias and appropriately accounting for missing physical processes in the thermospheric heating through the photoelectron heating efficiency.

Characteristics and mechanisms of the annual asymmetry of thermospheric mass density

In this paper, globally-averaged, thermospheric total mass density, derived from the orbits of ∼5000 objects at 250, 400, and 550 km that were tracked from 1967 to 2006, has been used to quantitatively study the annual asymmetry of thermospheric mass density and its mechanism(s). The results show that thermospheric mass density had a significant annual asymmetry, which changed from year to year. The annual asymmetry at the three altitudes varied synchronously and its absolute value increased with altitudes. The results suggest that there is an annual asymmetry in solar EUV radiation that is caused by the difference in the Sun-Earth distance between the two solstices and the random variation of solar activity within a year. This change in radiation results in an annual change in the thermospheric temperature and thus the scale height of the neutral gas, and is the main cause of the annual asymmetry of thermospheric mass density. The annual asymmetry of mass density increases with altitude because of the accumulating effect of the changes in neutral temperature and scale height in the vertical direction.

Remote Sensing of Earth's Limb by TIMED/GUVI: Retrieval of thermospheric composition and temperature

AbstractThe Global Ultraviolet Imager (GUVI) onboard the Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics (TIMED) satellite senses far ultraviolet emissions from O and N2 in the thermosphere. Transformation of far ultraviolet radiances measured on the Earth limb into O, N2, and O2 number densities and temperature quantifies these responses and demonstrates the value of simultaneous altitude and geographic information. Composition and temperature variations are available from 2002 to 2007. This paper documents the extraction of these data products from the limb emission rates. We present the characteristics of the GUVI limb observations, retrievals of thermospheric neutral composition and temperature from the forward model, and the dramatic changes of the thermosphere with the solar cycle and geomagnetic activity. We examine the solar extreme ultraviolet (EUV) irradiance magnitude and trends through comparison with simultaneous Solar Extreme EUV (SEE) measurements on TIMED and find the EUV irradiance inferred from GUVI averaged (2002–2007) 30% lower magnitude than SEE version 11 and varied less with solar activity. The smaller GUVI variability is not consistent with the view that lower solar EUV radiation during the past solar minimum is the cause of historically low thermospheric mass densities. Thermospheric O and N2 densities are lower than the NRLMSISE‐00 model, but O2 is consistent. We list some lessons learned from the GUVI program along with several unresolved issues.

Attribution of interminima changes in the global thermosphere and ionosphere

AbstractWe present a statistical attribution analysis of the changes in global annual average thermospheric mass density and ionospheric total electron content (TEC) between the cycle 22/23 solar minimum (which occurred at epoch 1996.4) and the prolonged cycle 23/24 minimum (2008.8). The mass density data are derived from orbital drag, and the TEC data are derived from ground‐based GPS receivers. The interminima change in mass density was −36% relative to the 1996.4 yearly average. Considering each multiplicative forcing independently, lower average geomagnetic activity during the cycle 23/24 minimum produced an interminima density change of at least −14%, solar extreme ultraviolet (EUV) irradiance forcing produced a density change of −1% to −13%, and changes in thermospheric CO2 concentration produced a density change of −5%. There was essentially no interminima change in global TEC derived from ground‐based GPS receivers or space‐based altimeters, even though past behavior suggests that it should have changed −3% (0.2 TEC units (1 TECU = 1016 el m−2)) in response to lower geomagnetic activity and −1% to −9% (0.1–0.8 TECU) in response to lower EUV irradiance. There is large uncertainty in the interminima change of solar EUV irradiance; the mass density and TEC data suggest a plausible range of 0% to −6%.

Geospace variability during the 2008–2009 Whole Heliosphere Intervals

AbstractWe simulate the ionosphere and thermosphere throughout the extended solar minimum epoch from 2008 to 2009 using geospace models, systematically validating the models with databases of observed geospace composition. We isolate and quantify observed changes of as much as 4 total electron content unit (TECU) (1 TECU = 1016 elections m−2) (~36%) in global (60°S−60°N) ionospheric total electron density and as much as 19 × 10−12 kg m−3 (~75%) in global thermospheric mass density at 250 km associated with fluctuating solar EUV radiation and geomagnetic activity during this nominally “quiet” period. Corresponding modeled responses to both solar EUV radiation and geomagnetic activity are about a factor of 2 smaller than is observed. We identify, as well, semiannual and annual oscillations that produce geospace variability comparable to that produced by external solar and geomagnetic influences, and which cause distinct differences among the three individual Whole Heliosphere Intervals. From the first Whole Heliosphere Interval (March–April 2008) to the third Whole Heliosphere Interval (June–July 2009) total electron content (60°S−60°N) decreased 3.6 TECU (~32%) and mass density at 250 km decreased 9 × 10−12 kg m−3 (~34%) due to these oscillations. Reliable attribution of the geospace base state during the 2008–2009 solar minimum epoch and geospace comparisons among the Whole Heliosphere Intervals thus requires that the semiannual and annual oscillations be properly distinguished in addition to the concurrent solar and heliospheric effects which have been the primary goal of the majority of Whole Heliosphere Interval (WHI) characterizations.

Altitude variations in the thermosphere mass density response to geomagnetic activity during the recent solar minimum

AbstractAccelerometer data from coplanar orbits of Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites were used to study the complex altitude and latitude variations of the thermosphere mass density response to geomagnetic activity during 1–10 December 2008 near 09 LT. Helium number densities near 500 km altitude were extracted from the CHAMP and GRACE measurements and clearly show the presence of a winter hemisphere helium bulge. This recent extreme solar minimum indicates that wintertime helium concentrations exceed NRLMSISE‐00 model estimates by 30%–70% during quiet geomagnetic activity after adjusting F10.7 input into MSIS. The perturbation in mass density from quiet to active conditions is found to be less enhanced in the winter hemisphere at the higher GRACE altitudes (25%) than at the lower CHAMP altitudes (60%) and is attributed to dynamic behavior in the helium/oxygen transition. The investigation revealed the maximum storm time density perturbation to occur near the He/O transition region with a much weaker maximum near the O/N2 transition region. The altitude of maximum density perturbation occurs where the perturbation in the weighted pressure scale height is equal and opposite to the perturbation in the weighted mean molecular weight scale height. The altitude structure of density scale height perturbation is significantly influenced by the changes in the molecular weight scale height and can account for 50% of the change in mass density scale height in a region correspondingly close to the He/O transition during the 2008 solar minimum period.

Introduction to the special section on Sun‐Earth system response to extreme solar and seismic events

Introduction to the special section on Sun‐Earth system response to extreme solar and seismic events

The Anemomilos prediction methodology for Dst

AbstractThis paper describes new capabilities for operational geomagnetic Disturbance storm time (Dst) index forecasts. We present a data‐driven, deterministic algorithm called Anemomilos for forecasting Dst out to a maximum of 6 days for large, medium, and small storms, depending upon transit time to the Earth. This capability is used for operational satellite management and debris avoidance in Low Earth Orbit (LEO). Anemomilos has a 15 min cadence, 1 h time granularity, 144 h prediction window (+6 days), and up to 1 h latency. A new finding is that nearly all flare events above a certain irradiance threshold, occurring within a defined solar longitude/latitude region and having sufficient estimated liftoff velocity of ejected material, will produce a geoeffective Dst perturbation. Three solar observables are used for operational Dst forecasting: flare magnitude, integrated flare irradiance through time, and event location. Magnitude is a proxy for ejecta quantity or mass and, combined with speed derived from the integrated flare irradiance, represents the kinetic energy. Speed is estimated as the line‐of‐sight velocity for events within 45° radial of solar disk center. Storms resulting from high‐speed streams emanating from coronal holes are not modeled or predicted. A new result is that solar disk, not limb, observable features are used for predictive techniques. Comparisons between Anemomilos predicted and measured Dst for every hour over 25 months in three continuous time frames between 2001 (high solar activity), 2005 (low solar activity), and 2012 (rising solar activity) are shown. The Anemomilos operational algorithm was developed for a specific customer use related to thermospheric mass density forecasting. It is an operational space weather technology breakthrough using solar disk observables to predict geomagnetically effective Dst up to several days at 1 h time granularity. Real‐time forecasts are presented at http://sol.spacenvironment.net/~sam_ops/index.html?

The relationship of thermospheric density anomaly with electron temperature, small-scale FAC, and ion up-flow in the cusp region, as observed by CHAMP and DMSP satellites

Abstract. We present in a statistical study a comparison of thermospheric mass density enhancements (ρrel) with electron temperature (Te), small-scale field-aligned currents (SSFACs), and vertical ion velocity (Vz) at high latitudes around noon magnetic local time (MLT). Satellite data from CHAMP (CHAllenging Minisatellite Payload) and DMSP (Defense Meteorological Satellite Program) sampling the Northern Hemisphere during the years 2002–2005 are used. In a first step we investigate the distribution of the measured quantities in a magnetic latitude (MLat) versus MLT frame. All considered variables exhibit prominent peak amplitudes in the cusp region. A superposed epoch analysis was performed to examine causal relationship between the quantities. The occurrence of a thermospheric relative mass density anomaly, ρrel >1.2, in the cusp region is defining an event. The location of the density peak is taken as a reference latitude (Δ MLat = 0°). Interestingly, all the considered quantities, SSFACs, Te, and Vz are co-located with the density anomaly. The amplitudes of the peaks exhibit different characters of seasonal variation. The average relative density enhancement of the more prominent density peaks considered in this study amounts to 1.33 during all seasons. As expected, SSFACs are largest in summer with average amplitudes equal to 2.56 μA m−2, decaying to 2.00 μA m−2 in winter. The event related enhancements of Te and Vz are both largest in winter (Δ Te =730 K, Vz =136 m s−1) and smallest in summer (Δ Te = 377 K, Vz = 57 m s−1. Based on the similarity of the seasonal behaviour we suggest a close relationship between these two quantities. A correlation analysis supports a linear relation with a high coefficient greater than or equal to 0.93, irrespective of season. Our preferred explanation is that dayside reconnection fuels Joule heating of the thermosphere causing air upwelling and at the same time heating of the electron gas that pulls up ions along affected flux tubes.

Empirical model of the thermospheric mass density based on CHAMP satellite observations

The decadal observations from CHAMP satellite have provided ample information on the Earth's upper thermosphere, reshaping our understandings of the vertical coupling in the atmosphere and near‐Earth space. An empirical model of the thermospheric mass density is constructed from these high‐resolution observations using the multivariable least‐squares fitting method. It describes the density variation with latitude, longitude, height, local time, season, and solar and geomagnetic activity levels within the altitude range of 350–420 km. It represents well prominent thermosphere structures like the equatorial mass density anomaly (EMA) and the wave‐4 longitudinal pattern. Furthermore, the empirical model reveals two distinct features. First, the EMA is found to have a clear altitude dependence, with its crests moving equatorward with increasing altitude. Second, the equinoctial asymmetry is found to strongly depend on solar cycle, with its magnitude and phase being strongly regulated by solar activity levels. The equinoctial density maxima occur significantly after the actual equinox dates toward solar minimum, which may signal growing influence from the lower atmosphere forcing. This empirical model provides an instructive tool in exploring thermospheric density structures and dynamics. It can also be easily incorporated into other models to have a more accurate description of the background thermosphere, for both scientific and practical purposes.

Controlling of merging electric field and IMF magnitude on storm-time changes in thermospheric mass density

Abstract. The controls of merging electrical field, Em, and IMF (interplanetary magnetic field) magnitude, B, on the storm-time changes in upper thermospheric mass density are statistically investigated using GRACE accelerometer observations and the OMNI data of solar wind and IMF for 35 great storms during 2002–2006. It reveals the following: (1) The correlation coefficients between the air mass density changes and the parameters of Em and B are generally larger at lower latitudes than at higher latitudes, and larger in noon and midnight sectors than in dawn and dusk. (2) The most likely delay time (MLDT) of mass density changes in respect to Em is about 1.5 h (4.5 h) at high (low) latitudes, having no distinct local time dependence, while it is 6 h at middle latitudes in all the local time sectors except for noon, which is longer than at low latitudes. A similar fact of longer delay time at mid-latitude is also seen for B. The MLDTs for B at various latitudes are all local time dependent distinctly with shorter delay time in noon/midnight sector and larger in dawn/dusk. Despite of widely spread of the delay time, IMF B exhibits still larger correlation coefficients with mass density changes among the interplanetary parameters. (3) The linear control factor of B on the density changes increases for large B, in contrast to somewhat saturation trend for larger Em. (4) The influence of B and Em on the mass densities shows different behavior for different types of storms. The influence intensity of Em is much stronger for CIR-driven than for CME-driven storm, while it is not so distinct for B. On the local time asymmetry of the influence, both Em and B have largest influence at noon sector for CME-driven storms, while an obviously larger intensification of the influence is found in dawn/dusk sector during CIR storms, especially for parameter Em.

The longitudinal variation of the daily mean thermospheric mass density

This study uses the GRACE (Gravity Recovery And Climate Experiment) and CHAMP (CHAllenging Minisatellite Payload) accelerometer measurements from 2003 to 2008. These measurements gave thermospheric mass densities at ~480 km (GRACE) and ~380 km (CHAMP), respectively. We found that there are strong longitude variations in the daily mean thermospheric mass density. These variations are global and have the similar characteristics at the two heights under geomagnetically quiet conditions (Ap < 10). The largest relative longitudinal changes of the daily mean thermospheric mass density occur at high latitudes from October to February in the Northern Hemisphere and from March to September in the Southern Hemisphere. The positive density peaks locate always near the magnetic poles. The high density regions extend toward lower latitudes and even into the opposite hemisphere. This extension appears to be tilted westward, but mostly is confined to the longitudes where the magnetic poles are located. Thus, the relative longitudinal changes of the daily mean thermospheric mass density have strong seasonal variations and show an annual oscillation at high and middle latitudes but a semiannual oscillation around the equator. Our results suggest that heating of the magnetospheric origin in the auroral region is most likely the cause of these observed longitudinal structures. Our results also show that the relative longitude variation of the daily mean thermospheric mass density is hemispherically asymmetric and more pronounced in the Southern Hemisphere.

Observations of increasing carbon dioxide concentration in Earth’s thermosphere

Carbon dioxide occurs naturally throughout Earth’s atmosphere. In the thermosphere, CO2 is the primary radiative cooling agent and fundamentally affects the energy balance and temperature of this high-altitude atmospheric layer 1,2 . Anthropogenic CO2 increases are expected to propagate upward throughout the entire atmosphere, which should result in a cooler, more contracted thermosphere 3‐5 . This contraction, in turn, will reduce atmospheric drag on satellites and may have adverse consequences for the orbital debris environment that is already unstable 6,7 . However, observed thermospheric mass density trends derived from satellite orbits are generally stronger than model predictions 8,9 , indicating that our quantitative understanding of these changes is incomplete. So far, CO2 trends have been measured only up to 35 km altitude 10‐12 . Here, we present direct evidence that CO2 concentrations in the upper atmosphere—probably the primary driver of long-term thermospheric trends—are increasing. We analyse eight years of CO2 and carbon monoxide mixing ratios derived from satellite-based solar occultation spectra. After correcting for seasonal‐latitudinal and solar influences, we obtain an estimated global increase in COx (CO2 and CO, combined) concentrations of 23:5 6:3 ppm per decade at an altitude of 101 km, about 10 ppm per decade faster than predicted by an upper atmospheric model. We suggest that this discrepancy may explain why the thermospheric density decrease is stronger than expected. In the mesosphere (5090km altitude) and thermosphere (>90km), almost all carbon is partitioned between CO2 and CO through ultraviolet photolysis of CO2 to create CO and chemical loss of CO to re-form CO2 (refs 1,13). The photochemistry and atmospheric dynamics introduce solar cycle, seasonal and latitudinal dependences into the partitioning and the overall carbon abundance 13,14 . The CO2 volume mixing ratio (VMR) is approximately constant up to 6580km and falls off rapidly at higher altitudes owing to molecular diffusion and photolysis 13 . The proportion of carbon in the form of CO increases from less than 3% below 80km to more than 20% above 100km (refs 13,14). CO2 cools the mesosphere and thermosphere through collisional excitation (by atomic oxygen) of its bending vibrational mode and subsequent 15m

Enhancement of thermospheric mass density by soft electron precipitation

Enhancements in F‐region electron density and temperature and bottomside Pedersen conductivity caused by soft electron precipitation are shown to enhance the Joule heating per unit mass and the mass density of the thermosphere atF‐region altitudes. The results are derived from the coupled magnetosphere‐ionosphere‐thermosphere model (CMIT) including two types of causally specified soft electron precipitation—direct‐entry cusp precipitation and Alfvén‐wave induced, broadband electron precipitation—the effects of which are self‐consistently included for the first time in a coupled global simulation model. The simulation results provide a causal explanation of CHAMP satellite measurements of statistical enhancements in thermospheric mass density at 400 km altitudes in the cusp and premidnight auroral region.

Numerical modeling of solar wind influences on the dynamics of the high-latitude upper atmosphere

Abstract. Neutral thermospheric wind patterns at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both polar regions are used to deduce statistical neutral wind vorticity distributions and were analyzed in their dependence on the Interplanetary Magnetic Field (IMF). The average pattern confirms the large duskside anticyclonic vortex seen in the average wind pattern and reveals a positive (cyclonic) vorticity on the dawnside, which is almost equal in magnitude to the duskside negative one. The IMF dependence of the vorticity pattern resembles the characteristic field-aligned current (FAC) and ionospheric plasma drift pattern known from various statistical studies obtained under the same sorting conditions as, e.g., the EDI Cluster statistical drift pattern. There is evidence for hemispheric differences in the average magnitudes of the statistical patterns both for plasma drift and even more for the neutral wind vorticity. The paper aims at a better understanding of the globally interconnected complex plasma physical and electrodynamic processes of Earth's upper atmosphere by means of first-principle numerical modeling using the Upper Atmosphere Model (UAM). The simulations of, e.g., thermospheric neutral wind and mass density at high latitudes are compared with CHAMP observations for varying IMF conditions. They show an immediate response of the upper atmosphere and its high sensitivity to IMF changes in strength and orientation.