Nowcast model of low energy electrons (1-150 keV)

for surface charging hazards

Natalia Ganushkina

Finnish Meteorological Institute, Helsinki, Finland

AMC 12 CEASE II ESA dataGeostationary satellite measures energy electron fluxes of 5 - 50 keV.

During the periods of increased low energy electron fluxes, there exist the clear increase in the spacecraft potential magnitudes.

Basic level

Basic level

100 times increase

100 times increase

3

Need to have a model for low energy electrons in the near -Earth space

• No continuous measurements of radiation environment.

• No continuous simultaneous measurements of spacecraft potential

• Need to know what level of low energy electron flux (level of risk of surface charging) is and will be at times and locations where we do not have any measurements.

KNOW NOW AND PREDICTWith the development of the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM), the computational view on the low energy electron fluxes in the near-Earth space is now feasible

What do we present?IMPTAM (Inner Magnetosphere Particle Transport and Acceleration model): nowcast model for low energy (< 200 keV) electrons in the near-Earth geospace, operating online

under the SPACECAST project (http://fp7-spacecast.eu)

Why this model is important?Low energy electron fluxes are very important to specify when hazardous satellite surface charging phenomena are considered. They constitute the low energy part of the seed population for the high energy MeV particles in the radiation belts

What does the model provide?The presented model provides the low energy electron flux at all locations and at all satellite orbits, when necessary, in the near-Earth space.

What are the drivers of the model?The model is driven by the real time solar wind and Interplanetary Magnetic Field parameters with 1 hour time shift for propagation to the Earth’s magnetopause, and by the real time geomagnetic activity index Dst.

The Model: IMPTAM

Aurinko-Maa-vuorovaikutus

149,600,000 km Earth’s magnetosphere

Solar wind driving the Earth’s magnetosphere

All dynamicsdriven bysolar windfrom the Sun

Sun-Earth interactions: Where do low energy electrons come from?

Sun-Earth interactions: Where do low energy electrons come from?

Challenges for modeling of low energy electrons in the near-Earth

• We model motion of electrons in magnetic and electric fields:Correct models for these fields are extremely hard to develop

• There is still a debate going on about the locations and timing of electron transport and energy increase when they come to geostationar and inside the geostationary

• Specification of a correct initial flux to start our modeling from is very nontrivial

We use the best available models to set our IMPTAM

Very good agreement with the measurements indicates that the assumptions and physics in IMPTAM are correct and model can be trusted when made operational

IMPTAM flux

February 28 – March 3, 2013 modeling resultsfor 15-50 keV (AMC 12 geostationary)

data

model

Basic level

Basic level

100 times increase

100 (up to 500) times increase

It is extremely difficult to have comparable to the observations model fluxes at the exact location of a real satellite – very reasonable agreement which we obtained is a remarkable achievement of IMPTAM modeling

February 28 – March 3, 2013 modeling resultsfor 5-15 keV (AMC12 geostationary)

100 times increase

100 (up to 500) times increase

data

model

Basic level

Basic level

It is extremely difficult to have comparable to the observations model fluxes at the exact location of a real satellite – very reasonable agreement which we obtained is a remarkable achievement of IMPTAM modeling

Summary of achievements

• Very challenging task to model time-dependent variations of low energy electron fluxes

• Model is operating online 24/7 giving the output very close to the observed low energy electron fluxes at GOES 13 geostationary satellite (Daniel Heynderickx’s presentation)

• Continuous work on past event modeling and comparison with available data in the near-Earth space to further validation and improvement of the model

• Model coupling to the models of higher energy electrons in radiation belts (BAS, ONERA) is under development (Vincent Maget’s presentation)

• Model output is AVAILABLE as nowcast and on demand