# Presentation: 874589

## Welcome to UM, LowellBodo ReinischCharge to the RPI NARJim BurchRobert Carovillano

## Charge to the RPI NAR

- The Review Team is to evaluate the IMAGE/RPI experiment with regard to the feasibility of accomplishing each of the mission science objectives. As stated in the Level 1 Requirements Definition document for IMAGE these objectives are:
- 1) What is the mechanism for injecting plasma into the magnetosphere on substorm and magnetic storm time scales?
- 2) What is the directly driven response of the magnetosphere to solar wind changes?
- 3) How and where are magnetospheric plasmas energized, transported, and subsequently lost during storms and substorms?
- Specific RPI measurement characteristics required to meet these science objectives are giving in Table 1 of the Level 1 Requirements Definition document.

## RPI Team IntroductionBodo Reinisch

## RPI Science Team

**Bodo W. Reinisch, Wynne Calvert, Mark Haines - University of Mass., Lowell**
**James L. Green****, ****Robert F. Benson****, ****Shing F. Fung, Mark Smith - GSFC**
**Dennis Gallagher - MSFC**
**Patricia H. Reiff - Rice University**
**William W. L. Taylor - Hughes STX**
**Donald Carpenter - Stanford University**
**Jean-Louis Bougeret, Robert Manning - Meudon Paris**
**RPI Science Team formed in October 1992 to support the IMI Science Definition teams study of radio imaging**

## RPI Team Publications

**Calvert, W., R. F. Benson, D. L. Carpenter, S. F. Fung, D. Gallagher, J. L. Green, P. H. Reiff, B. W. Reinisch, M. Smith, and W. W. L. Taylor, The feasibility of radio sounding of the magnetosphere, Radio Sci., 30, 5, 1577-1595, 1995.**
**Calvert, W., R. F. Benson, D. L. Carpenter, S. F. Fung, D. Gallagher, J. L. Green, D. M. Haines, P. H. Reiff, B. W. Reinisch, M. Smith and W. W. L.Taylor, Reply to R. A. Greenwald concerning the feasibility of radio sounding of the magnetosphere, Radio Sci., in press, 1996.**
**Fung, S. F., and J. L. Green, Global Imaging and Radio Remote Sensing of the Magnetosphere, To be published in Workshop on Radiation Belts: Models and Standards, AGU Monograph 97, 285-290, 1996.**
**Green, J. L., R. F. Benson, W. Calvert, S. F. Fung, P. H. Reiff, B. W. Reinisch, and W. W. L. Taylor, A Study of Radio Plasma Imaging for the proposed IMI mission, NSSDC Technical Publication, February 1993. **
**Green, J. L., W. W. L. Taylor, S. F. Fung, R. F. Benson, W. Calvert, B. W. Reinisch, D. Gallagher, and P. H. Reiff, Radio remote sensing of magnetospheric plasmas, To be published in Proceedings of the Chapman Conference on Measurement Techniques for Space Plasmas: What works and what doesn't, 1996. **
**Green, J. L., S. F. Fung, and J. L. Burch, Application of magnetospheric imaging techniques to global substorm dynamics, Proceedings of the 3rd International Conference on Substorms, Versailles, ESA, SP-389, 655-661, 1996.**
**Reiff, P. H., J. L. Green, R. F. Benson, D. L. Carpenter, W. Calvert, S. F. Fung, D. Gallagher, B. W. Reinisch, M. F. Smith, and W. W. L. Taylor, Radio imaging of the magnetosphere, Feature article in EOS, 75, 129, 133, and 134, 1994. **
**Reiff, P. H., J. L. Green, R. F. Benson, D. L. Carpenter, W. Calvert, S. F. Fung, D. Gallagher, Y. Omura, B. W. Reinisch, M. F. Smith, and W. W. L. Taylor, Remote sensing of substorm dynamics via radio sounding, Substorms 2, Proceedings of the Second International Conference on Substorms, Ed. J. R. Kan, J. D. Craven and S.-I. Akasofu, University of Alaska Press, Fairbanks, Alaska, 281-287, 1994.**
**Reiff, P. H., J. L. Green, S. F. Fung, R. F. Benson, W. Calvert, and W. W. L. Taylor,  Radio Sounding of Multiscale Plasmas, To be published in the Physics of Space Plasmas, 14, 1996.**

## IMAGE/ RPI Science Objectives

## IMAGE Science Objectives

**RPI observations:**
- Plasma entry at the magnetopause
- Determine thickness of the magnetopause boundary layer at several locations simultaneously under variable solar wind conditions
- Distinguish temporal and spatial variations
- Plasma entry via the polar cusp
- Obtain location, size, density profile of the polar cusp
- Distinguish temporal and spatial variations
**RPI supporting observations: **
- Plasma entry from the ionosphere: support  LENA observations
- Measure plasma density profile: to provide ground truth for EUV observations
- Observe cusp shape: support cusp footprint observations by FUV

**What are the dominant mechanisms for injecting plasma into the magnetosphere on substorm and magnetic storm time scales?**

## IMAGE Science Objective (cont.)

- Quantitative measurement of the structure and dynamics of the magnetopause, boundary layers, cusp, plasmapause and plasmaspheric outliers
- Global topology of the magnetopause
**RPI supporting observations:**
- Detection of periodic waves on the magnetopause: support simultaneous auroral observations by FUV
- Plasmapause/sphere erosion and refilling: support related EUV observations

**IMAGE Science Objective (cont.)**

**What is the directly driven response of the magnetosphere to solar wind changes?**

## IMAGE Science Objectives (cont.)

**RPI global context observations:**
- Identify the dynamic responses and connectivity between magnetospheric regions: support all IMAGE instruments
- Plasmapause/sphere erosion and refilling: support EUV observations
- Plasmasphere dynamics: support NAI ring current observations

**How and where are magnetospheric plasmas energized, transported, and subsequently lost during storms and substorms?**

## Remote sensing with RPIBodo Reinisch

## Representative RPI Targets

**Magnetopause boundary layer****	****5 -20****	****20 - 40**
**Polar Cusp ****	****7 - 30****	****25 - 50**
**Magnetopause****	****10 - 60****	****30 - 70**
**Plasmapause****	****30 - 800****	****50 - 250**
**Plasmasphere****	****800 - 8x10****3****	****250 - 800**
**Ionosphere****	****8x10****3  ****- 1x10****5****	****800 - 3000**
**	****RPI will detect these targets sufficiently often to define their structures and motions**

**	****Electron Density ****	****Plasma Freq.**
**Target****	****Range (cm****-3****)****	****Range (kHz)**

## Factors for Magnetospheric Sounding

**Plasma Scale Lengths**
**Plasma Dynamics**
**Plasma Density Gradients**
**Sounding Geometry**
**Signal To Noise Ratio**
**Extensive ionospheric sounding experience gives experimentally verifiable limits for the magnetospheric sounding**

## RPI Instrument Requirements

## RPI Performance Requirements

## RPI HeritageRadio Plasma ImagingBodo Reinisch

## RPI ScienceJames L. Green 

## Overview of Radio Plasma Imaging (RPI)

**RPI transmits coded electromagnetic waves and receives resulting echoes at 3 kHz to 3 MHz**
**RPI uses a tri-axial orthogonal antenna system**
- 500 meter tip-to-tip x and y axis dipole antennas
- 20 meters tip-to-tip z axis dipole antenna
- Transmitter can utilize either x or y or both x and y axis antennas
- Echo reception on all three axes
**Basic RPI measurements of an echo at a selected frequency **
- Amplitude
- Time delay (distance or range from target)
- Direction
- Wave polarization (ordinary or extra-ordinary)
- Doppler shift and frequency dispersion

## Principles of Wave Reflection in Plasmas

**Radio waves are reflected at wave cutoffs (n = 0)**
**In a cold, magnetized plasma**
- Ordinary (O-mode): Wave frequency =  *f**p*
- Extraordinary (X-mode): Wave frequency =
**Echo from reflections perpendicular to density contours**

**Echo**

**Refracted rays**

**Refracted rays**

- n=0

- n>0

- n<0

## Physics of Magnetospheric Radio SoundingWynne Calvert

## Characteristic Scales Near the Magnetopause(Song, 1995)

_**Length**_**	**_**Physical Scale**_**	**_**Phenomena**_
**20~500 m****	****Debye Length****	****Affect E field measurement**
**0.5 km****	****Electron gyroradius****	****No coherent macrostructure, waves**
**1 km****	****Electron skin depth****	****No coherent macrostructure, waves**
**5 km****	****Lower hybrid radius****	****Waves, sharp edges?**
**50~100 km****	****Ion gyroradius****	****Sharp edges, waves**
**10****2****~10****3**** km ****	****10~100 ion gyroradii****	****Layers, FTEs, waves, eddies?**
**(0.1~1 R****e****)**
**~10 Re****	****Size of magnetosphere****	****Tangential scale of MP surface waves**

## RPI Digital ProcessingMark Haines

## Noise EnvironmentJames Green

## Noise Environment Studies

**Extensive analysis on magnetospheric radio environment began during the IMI Science Definition Team (1993)**
**NRA proposals submitted for support **
- Plasma Wave Spectral Power Flux Model of the Inner Magnetosphere (93-OSS-01)
- Plasma Wave Imaging of the Earth's Magnetosphere (NRA-95-OSS-11)
**Completed Plasma and Radio Wave Imaging Survey placed results on the Web in April 1995**
- http://bolero.gsfc.nasa.gov/~wave/wsurvey.html
**Results used to support a polar orbit for IMAGE**
**Presented results at AGU (Fall ‘95, Spring ‘96, and Fall ‘96)**

## Natural Radio Emissions

**Natural radio emissions are “interference” for RPI**
- Characterized as either broad-band or narrow-band
**Natural noise interference at RPI frequencies include:**
- Solar Type III Radio Bursts
- Auroral Kilometric Radiation
- Non-thermal Continuum Radiation (trapped and escaping)
**Solar Type III Radio Bursts **
- Very intense drifting broad-band emissions from ~ 30 kHz to ~ 1 MHz
- Highly variable in their frequency of occurrence associated with solar active regions
- Electromagnetic radiation at 2fp of the local solar wind
- We do not expect RPI will be able to sound through bursts
**Auroral Kilometric Radiation**
- Very intense narrow-band emission from ~ 50 kHz to ~ 800 kHz
- Well known angular distribution
- Will utilize RPI’s frequency agility

## Continuum: Previous Results

**Key observations of the Earth’s non-thermal continuum:**
- Contains both “trapped” and “escaping” components
- Source region is at low latitude on the morning side near the plasmaspause
- Believed to be generated when Fuhr = (n+1/2)Fg
**Escaping continuum:**
- Frequency range: ~35 to ~ 100 kHz
- Seen both inside and outside the magnetosphere
- Observed as narrow “discrete” frequency bands
**Trapped Continuum:**
- Frequency range:~ 15 kHz to ~ 35 kHz
- Believe to occur due to Doppler shifting of multiple reflections off the magnetopause and plasmapause of the “discrete” emission
- Upper frequency limit believed to be the magnetopause plasma frequency
- Originally considered to be only a “broad-band” emission
- Because observations were at low latitudes, previously believed by some to completely fill the magnetosphere

## Continuum Previous: Results (Cont.)

**DE-1 observations of escaping continuum (Gurnett and Morgan, 1991)**
- Direction finding results show distinct outward beaming from the equatorial plasmapause
**DE-1 observations of trapped continuum(Gurnett, et al., 1983)**
- “Radiation comparable to the trapped continuum radiation detected by Gurnett and Shaw [1973] near the equatorial plane has not yet been identified in the DE-1 data over the polar region.”
- “The improved sensitivity and frequency resolution available with the DE-1 instrument now allows us to unambiguously resolve these (Z mode and continuum) different emissions to an extent that simply was not possible with the 16 channel spectrum analyzer on Hawkeye.”
- “The Z-mode radiation probably corresponds to the noise previously identified as ‘continuum radiation’ in the Hawkeye polar region data.”
**Z-mode radiation is limited by the F****uhr**

## Continuum: RPI Team Results

**Continuum radiation from Hawkeye wave intensity maps**
- Continuum source and beaming pattern seen at 31.1 and 56 kHz but not at 100 kHz
- Radiation beamed outward from source region located outside dawnside plasmasphere
- 60% of 4 years of data at 31.1 kHz in the IMAGE orbit are at the receiver noise level
- Hawkeye observes weak continuum radiation with discrete structure at high latitudes
**Results from the ray tracing calculations**
- Both trapped and escaping continuum radiation can easily“leak” out of the magnetosphere
- Continuum radiation over the polar cap
- Expect the emission to be very weak
- Expect the emission to be “discrete” and not broad-banded
- Ray tracing confirms observations
**Earth’s non-thermal continuum radiation does not uniformly fill the magnetosphere as previously believed**
- Expect large variations in the wave emission pattern with the polar cap the best location

## Response to Issues

**Issues: Background continuum emission has been underestimated**
- Broadband non-thermal continuum radiation claimed to extend to high latitudes
- Thus it is claimed that RPI will not have adequate S/N ratio at most times and the range will be limited to much less than 4 Re
**Response:**
- Basis is on extrapolation of equatorial continuum observations
- Even Gurnett and Frank [1976] Hawkeye observations of continuum pertained to low latitudes
- Continuum radiation observed quantitatively at high latitudes during 7 passes of Hawkeye data over a 4 yr interval (Boardsen et al 1997)
- Continuum radiation observed only at low latitudes during 3 years of DE-1 data [Gurnett et al., 1983]
**Conclusion: Impact on RPI operations due to background continuum radiation should be minimal**

## BACKUP

## Ray Tracing Calculations

**Ray Tracing Code**
- Developed by Shawhan [1967] & modified by Green [1976], has supported over 26 studies during the last 15 years
- Uses the Haselgrove [1955] formalism and cold plasma dispersion relations [Stix, 1992]
**Three-dimensional magnetospheric plasma model**
- Diffusive equilibrium plasmasphere [Angerami & Thomas, 1964]
- Plasmapause model [Aikyo & Ondoh, 1971]
- Magnetopause boundary [Roelof & Sibeck, 1993]
- With Gaussian or multi-Gaussian density profile
**Magnetopause density characteristic of MHD models**
- 4 times the solar wind density at subsolar point
- 1.1 times the solar density at the dawn-dusk meridian
- Solar Wind electron density = 10 /cc

## SummaryBodo Reinisch