1. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 1 Neutral Atmosphere Density Interdisciplinary Research: (NADIR) A Multidisciplinary University Research Initiative (MURI) Sponsored by the Air Force Office of Scientific Research The objective of NADIR is to significantly advance understanding of drag forces on satellites, including density, winds, and factors affecting the drag coefficient. We seek a level of understanding that will enable specification and prediction at the “next level” of performance. Actual Position Predicted Position Co-Principal Investigators: Jeff Forbes and Tim Fuller-Rowell University of Colorado at Boulder Aug 2007 - Aug 2012 $7.2 M http://ccar.colorado.edu/muri/

2. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 2

3. 3 NADIR Participants Co-Investigators Rashid Akmaev, Brian Argrow, George Born, Geoff Crowley, David Falconer, Delores Knipp, USAFA Juan Fontenla, Tomoko Matsuo, Dusan Odstrcil, Joachim Raeder, Jeff Thayer, DoD Oversight Kent Miller, AFOSR; Joseph Liu, AFSPC; Robert McCoy, ONR Collaborators Jeffrey Anderson, NCAR Eugene Avrett, Harvard-SAO Christopher Bass, AFSPC Bruce Bowman, AFSPC Gary Bust, UTSA Mihail Codrescu, SEC, NOAA Doug Drob, NRL Irene Gonzalez-Hernandez, NSO Cheryl Huang, AFRL Chin Lin, AFRL Charles Lindsey, Co-RA Frank Marcos, AFRL Matthew McHarg, USAFA Craig McLaughlin, U Kansas Cliff Minter, NGA Steve Nerem, CU Andrew Nicholas, NRL Jens Oberheide, U Wuppertal Vic Pizzo, SEC, NOAA Eric Quemaris, CNRS Arthur Richmond, NCAR Stan Solomon, NCAR Thomas Woods, CU Administration Sarah Melssen, CU

4. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 4 1000 km

5. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 5 NADIR Methodology Better understand the physical processes Determine which of the processes create structure on a scale that is important to satellite drag. Determine the driver-response relationships - internal and external. Improve forecasts of the drivers. Determine the most valuable datasets required to specify the system state and forecast the drivers

6. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 6 Eight Focus Areas I.Scales of Density Variability, Winds, and Drag Prediction: What spatial and temporal scales of drag variability are most relevant to in- track error? II.Internal Processes and Thermosphere-Ionosphere Coupling: CHAMP Densities How do cooling processes regulate the response and recovery of magnetic storms? What is the impact of T-I coupling on the neutral density structure? What is the source of the semiannual variation and its solar cycle dependence?

7. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 7 Eight Focus Areas III.Energy Partitioning at High Latitudes and Density Implications How is magnetospheric energy input partitioned (Joule heating, momentum transfer, etc.) and what are the implications for density and density-driver -relationships? IV. Wave Forcing from the Lower Atmosphere What are the meteorological influences on thermosphere density, and can a predictive capability be developed? -- Joule Heating -- Density (Geoff Crowley - Numerical Experiments Using TIMEGCM Model)  4 hr delay

8. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 8 Eight Focus Areas V.Forecasting Geomagnetic Activity Objective: Use observations in the photosphere, corona, at L1 and numerical models of the heliosphere and magnetosphere to: (1)Improve existing empirical and numerical models of the heliosphere and geospace; and (2)Achieve more realistic short-term and probabilistic long-term forecasting. VI.Forecasting Solar EUV/UV Radiation Objective: Develop EUV & UV solar flux forecasts up to a few weeks using: (1)near-side solar observations and (2)far-side helio-seismological and L  -scattering observations

9. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 9 Eight Focus Areas VII.Driver-Response Relationships What are the dominant modes of density variability, and how do they relate to the drivers? VIII.Satellite Drag in the Transition Region Utilize Direct Simulation Monte Carlo (DSMC) methods to simulate and understand drag coefficient changes In the re-entry regime (ca. 150-90 km). Use tidal theory, wind and temperature Observations to model density variability in the re-entry regime.

10. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 10 Research Highlight: Rotating Solar Coronal Holes and Periodic Modulation of the Upper Atmosphere Lei, J., Thayer, J.P., Forbes, J.M., Sutton, E.K., and R.S. Nerem, Rotating Solar Coronal Holes and Periodic Modulation of the Upper Atmosphere, Geophys. Res. Lett., in press, 2008. Thayer, J.P., Lei, J., Forbes, J.M., Sutton, E.K., and R.S. Nerem, Thermospheric Density Oscillations due to Periodic Solar Wind Fast Streams, J. Geophys. Res., in press, 2008. Lei, J., Thayer, J.P., Forbes, J.M., Sutton, E.K.,Nerem, R.S., Temmer, M., and A.M. Veronig, Periodic oscillations in thermospheric density measured by the CHAMP satellite during the declining phase of solar cycle 23, J. Geophys. Res., submitted, 2008.

11. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 11 During declining and low solar activity, multiple rotating coronal holes produce periodic high-speed solar wind streams. At Earth, these high-speed streams modulate geomagnetic activity in the geospace environment with the same periodicity.

12. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 12 Thermosphere Density - 400 km F10.7 Solar Wind Speed Kp

13. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 13 TIMED/SEE Thermosphere Density - 400 km F10.7 Solar Wind Speed Kp Spectra for all of 2005 A triad of coronal holes during 2005 leads to a 27d/3 = 9d periodicity in thermosphere density

14. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 14 Density at 400 km An element of predictability is inherent in this phenomenon! Latitude Structure of Density Response A: Actual Data B: Band-Pass Filtered Data Percent density change

15. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 15 27d/3 = 9.0 27d Thermosphere Density - 400 km F10.7 Solar Wind Speed Kp Thermosphere Density - 400 km 27d/4 = 6.8 27d/2 = 13.5

16. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 16 google: ‘asen-5335’

17. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 17 Additional Slides More Details of Focus Areas

18. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 18 Focus Area I: Scales of Density Variability, Winds, and Drag Prediction Forbes, Born, McLaughlin, Thayer, Fuller-Rowell Methodology: A test bed of satellites will be used to perform satellite orbit predictions, and to evaluate predicted versus actual in-track satellite positions (“in- track errors”) in terms of characteristics of density variability (e.g., scale size). Anticipated Outcome: Understand what spatial and temporal resolutions that both empirical and first-principles models should seek to achieve, as well as the required temporal resolution of geophysical indices or data that drive the models. Sample Question: What spatial and temporal scales of drag variability are most relevant to in-track error? Objectives Gain quantitative knowledge and a deeper understanding of how prediction error depends on the various facets of density variability. Connect our scientific research activities to the actual prediction of satellite ephemerides. CHAMP Densities

19. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 19 Sample Questions: What is the impact of T-I coupling on the neutral density structure? What is the source of the semiannual variation and its solar cycle dependence? How do cooling processes regulate the response and recovery of magnetic storms? Focus Area II: Internal Processes and Thermosphere-Ionosphere Coupling Fuller-Rowell, Forbes, Thayer, Codrescu, Crowley, Solomon, Richmond Relationship between  and N e - from CHAMP Objective: Attain improved understanding of internal processes, and capture this understanding in the next generation of hybrid empirical/physical models.

20. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 20 Focus Area III: Energy Partitioning at High Latitudes and Density Implications Thayer, Fuller-Rowell, Codrescu, Crowley, Knipp, Forbes, Richmond Objectives Improve scientific understanding of the high latitude energy input; energy partitioning into other forms; neutral density and wind responses to these high latitude energy inputs. Develop driver-response relationships to improve empirical model specifications. Methodology: Numerical experiments to evaluate solar flux production of electron density and the concomitant change in the Joule heating rate; assess impact on global temperatures and density. Perform similar numerical experiments using empirical relations with kinetic energy flux and Poynting flux. Anticipated Outcome: Understand the correlations amongst the fluxes to develop driver-response relationships that may depend on multiple energy sources. Sample Question: In what ways are the solar flux, kinetic energy flux and Poynting flux related? 00 12 0618

21. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 21 Sample questions What are the observed characteristics? How are they connected to dynamical variations in the strato-mesosphere? Can PW-period density variations be empirically accounted for in models such as J70 and JB2006? Can PW periodicities in density be reliably predicted with whole-atmosphere models on time scales of ~one to two weeks in advance? Focus Area IV: Wave Forcing from the Lower Atmosphere Akmaev, Forbes, Fuller-Rowell Objectives Delineate density variations at planetary-wave (PW) periods (2-20 days) and understand their origin. Develop driver - response relationships to enable predictive capability.

22. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 Focus Area V: Forecasting Geomagnetic Activity Odstrcil, Pizzo, Falconer, Raeder, Fuller-Rowell Methodology: Use observations in the photosphere (left-top), corona (left-bottom), at L1 (bottom-center), and numerical models of the heliosphere (top-center) and magnetosphere (right). Anticipated Outcome: Improved forecasting ability with the lead times:  30-60 min: driving magnetospheric models by L1 observations;  1-3 days: driving heliospheric models by coronal observations;  3-5 days: using probability of solar magnetic eruptions. Objectives: Improve existing empirical and numerical models of the heliosphere and geospace to achieve more realistic short- term and probabilistic long- term forecasting.

23. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 23 Focus Area VI: Forecasting Solar EUV/UV Radiation Fontenla, Woods, Avrett, Quemaris, Lindsey Objective Develop forecasts of EUV and UV solar flux variability up to a few weeks in advance. Methodology Using various measurements of solar properties on the near-side (Earth-facing) part of the Sun, models of the solar atmosphere, and existing empirical relationships, construct solar spectra or “masks” for 10 positions on the solar disk each day. Validate against SORCE and other measurements. Use helio-seismological and L  scattering observations of the far- side of the Sun to apply corrections to the “obsolete”parts of the mask. (Active regions change since the last time they were seen on the near- side)

24. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 24

25. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 25 Focus Area VIII: Satellite Drag in the Re-Entry Region: Satellite Drag Brian Argrow and Jeff Forbes Motivation Accurate C D essential for drag prediction DSMC can be applied for transition flow regime Gas surface interaction models are the source of most error for current C D computations Methodology: Application of the Direct Simulation Monte Carlo (DSMC) for vehicle simulations from free-molecular flow to slip-flow regimes with emphasis on the gas- surface interaction model. Anticipated Outcome: Data base of altitude-dependent C D values for representative satellite geometries. Simulate aerodynamic forces for trajectory analysis DSMC Simulations of a Hypersonic Waverider at 100 km and 145 km (density contours) 100 km 145 km

26. AFOSR MURI: Neutral Atmosphere Interdisciplinary Research (NADIR) Space Weather Workshop, 2008 26 Focus Area VIII: Satellite Drag in the Re-Entry Region: Tidal and Longitude Variations in Density Jeff Forbes and Jens Oberheide Motivation Re-entry prediction an important problem. Few density measurements exist at re- entry altitudes (ca. 80-200 km) Strong longitude variations in tides known to exist in temperature and wind measurements Methodology: A fitting scheme using “Hough Mode Extensions” will be applied to TIMED/SABER and TIMED/TIDI measurements of temperatures and winds over 80- 120 km and -50 o to +50 o latitude during 2002-2006. Anticipated Outcome: global specifications of longitude-dependent tidal variations in density, winds, and temperature over the 80-200 km height region. Reconstructed Density Diurnal Amplitudes 110 km, September 2005