Examination of Three Empirical Atmospheric Models

Transcription

1 Examination of Three Empirical Atmospheric Models A Presentation Given to The Department of Physics Utah State University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy by David B. Hansen 4 February 2010 Space Weather Center Technical Report TR

2 Overview Motivation for empirical models Models to be discussed IRI MSIS HWM Items to consider for each model Model input and output parameters Valid domains within the model Model formulation Examples of model output 2

3 Why Create an Analytic Empirical Model? Provides a model based on observation More useful than data tables Theoretical models Initialization (background atmosphere) Verification of results Satellites Design Instrument data verification 3

4 (National Research Council, 1981) 4

5 International Reference Ionosphere 2007 (IRI2007) 5

6 IRI Description Empirical model ISO/TS (ISO Standard) Input Default: year, time of year, time of day, altitude, location Output Electron number density Ion number densities H, He, N, O, NO, O 2 Electron, ion, and neutral temperatures 6

7 Valid IRI Domains Year 1958-Present Time of year and time of day: no constraints Altitude Electron density: km Ion densities: km Temperatures: km Coordinates: global Best at mid-latitudes 7

8 IRI Data Sources Ground: Ionosonde: ne altitude profile Incoherent scatter radar: Te, ne, Ti, ni, mi, ui Satellite: Ionosonde: ne inverse altitude profile In-situ measurements along satellite trajectory Rocket: In-situ measurements along rocket trajectory Empirical Models: MSIS-86: Tn IGRF: geomagnetic field 8

9 Ionosonde Locations ( 9

10 Incoherent Scatter Radar Locations ( 10

11 IRI Data Fitting Altitude profile Epstein transition function Day of year Linear interpolation Latitude vs. longitude Spherical harmonics Time of day Epstein step function Magnetic and solar activity Linear interpolation 11

12 (Bradley and Dudendy, 1973) 12

13 Profile Parameters hmf2: height of F2 peak fof2: plasma frequency at F2 peak NmF2: plasma density at F2 peak ymf2: half thickness 13

14 (Anderson and Roble, 1981) 14

15 (Schunk and Nagy, 2000) 15

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22 March ; 14:22 (LT) o o 42.6 N; E (Roble, R. W., 1975) 22

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25 Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar 2000 (NRLMSISE-00) 25

26 MSIS Description Empirical Model Input Day of year, time of day, altitude, location, solar activity, magnetic activity Output Number densities of neutral species H, He, N, O, N2, O2, Ar Total mass density Temperature of neutral atmosphere 26

27 Valid MSIS Domains Day of year and time of day: no constraints Altitude He, N2, O2, and Ar densities: ground to exosphere O, H, and N densities: 72.5 km to exosphere Temperature: ground to exosphere Coordinates: global Solar and magnetic activity Above 80 km: user input Below 80 km: f10.7 = 150.0, Ap = 4.0 (recommended) 27

28 MSIS Data Sources Incoherent scatter radar: neutral temperature, N density 2 Satellite Mass spectrometer: neutral composition UV absorption: O2 density Accelerometer: total neutral mass density Drag: total neutral mass density Rocket Mass spectrometer: neutral composition UV absorption: O2 density Falling sphere: total neutral mass density Grenade: total neutral mass density Pressure gauge: total neutral mass density Handbook for MAP (Middle Atmosphere Program) Neutral temperature Total neutral mass density 28

29 MSIS Data Fitting Altitude profile Bates profile (low altitude) Inverse polynomial (high altitude) Latitude vs. longitude Spherical harmonics Solar and magnetic activity Polynomials Time variations (day of year, time of day) Fourier series 29

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36 Horizontal Wind Model 2007 (HWM07) 36

37 HWM Description Empirical model Input Day of year, time of day, altitude, geographic location, geomagnetic activity Output Northern wind speed Eastern wind speed 37

38 Valid HWM Domains Day of year and time of day: no constraints Altitude: km Coordinates: global Best at low and mid-latitudes Low solar activity 38

39 HWM Data Sources Ground Fabry-Perot interferometer Incoherent scatter radar Medium-frequency radar LIDAR Rocket Falling sphere Rocketsonde Trimethyl aluminum release Satellite In-situ measurements along satellite trajectory Fabry-Perot interferometer Numerical TIME-GCM NOAA GFS Analysis NASA GEOS4 Analysis 39

40 HWM Data Fitting Altitude profile Cubic spline (low altitude) Bates-Walker function (high altitude) Latitude vs. longitude Vector spherical harmonics Time variations Fourier series Magnetic activity Polynomial 40

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47 References AIAA PR G-003C-2010: Guide to Reference and Standard Atmosphere Models. American Institude of Aeronautics and Astronautics, Reston, VA. < Anderson, D. N., and R. G. Roble, Neutral wind effects on the equatorial F-region ionosphere, J. Atmos. Terr. Phys., 43, 835, Bilitza, D., and B. Reinisch, International Reference Ionosphere 2007: Improvements and new parameters, Advances in Space Research, 42, 4, , Bradley, P. A., and J. R. Dudeney, A simple model of the vertical distribution of the electron concentration in the ionosphere, J. Atmos. Terr. Phys., 35, 2131, Drob, D. P., et al., An empirical model of the Earth's horizontal wind fields: HWM07, Journal of Geophysical Research, 113, A12304, ISO/TS 16457:2009: Space systems - Space environment (natural and artificial) - The Earth's ionosphere model: international reference ionosphere (IRI) model and extensions to the plasmasphere. International Organization for Standardization, Geneva, Switzerland. < 47

48 References (continued) Picone, J. M., A. E. Hedin, D. P. Drob, and A. C. Aikin, NRLMSISE-00 empirical model of the atmosphere: Statistical comparisons and scientific issues, Journal of Geophysical Research, 107, A12, 1468, National Research Council, Solar-Terrestrial Research for the 1980's, National Academy Press, Washington, D.C., Roble, R. G., The calculated and observed diurnal variation of the ionosphere over Millstone Hill on March 23-24, 1970, Planet. Space Sci., 23, 1017, Schunk, R. W., and Nagy, A. F., Ionospheres: Physics, Plasma Physics, and Chemistry, Cambridge University Press, Cambridge, UK, 2000: 2nd Ed., Richard Stamper. Ionospheric Stations-The World. 6 May UK Solar System Data Center. 1 Feb < URSI Incoherent Scatter Working Group: Incoherent Scatter Radars. MIT Haystack Observatory. 1Feb < 48