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More progress on ‘linking together’ models

Nick AchilleosLecturer, Department of Physics

University College LondonWith thanks to Patrick Guio, Dugan Witherick and

William Nicholson

http://europlanet-ri.eu

Report from UCLWe have been pursuing activities which may produce some

useful ‘demonstrators’ and deliverables for the JRA3 Distributed Modelling Laboratory.

Modelling auroral dynamics at Jupiter (PhD project by J. N. Yates)

Coupling UCL Jovian magnetodisc model with a model of plasma flow (Achilleos, Guio)

Cpupling UCL Mars global model with Grenoble (LdP) model of suprathermal electron precipitation (Nicholson, Lilensten et al.)

http://europlanet-ri.euAuroral Dynamics at Jupiter

• Example 1

- The UCL global, axisymmetric model of Jupiter’s thermosphere and ionosphere (e.g. Smith and Aylward, Ann. Geo., 2009).

- Solves equations of fluid flow for the neutral thermosphere.

- Needs an algorithm for computing ionospheric current, esp. in the auroral region.

- Uses Model 2: the theoretical profile by Grodent and Gerard (JGR 2001) for auroral ionosphere (ion density versus altitude)

http://europlanet-ri.euModel Linkage

• Architecture: Auroral profile is built into a subroutine of UCL code

UCL model reads auroral profile as a ‘template’ for auroral ionosphere

The ion density profile is scaled at all altitudes by the same factor, according to the conductance properties calculated by the disc dynamics routine - gives plasma rotation rate and corresponding M-I currents.

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• For more information, see paper submitted to PSS by Yates, Achilleos and Guio (2010, arxiv)

• Grodent / Gerard profile (ascii files?) may be added to JRA3 Catalogue

• We need more 1D theoretical profiles of auroral structure so that we may use the UCL Jovian and Kronian models as a ‘testbed’ - this should be emphasised as a useful ‘byproduct’ of the DNML.

• Note also the work of Nicholson et al (MNRAS 2009) on precipitation at Mars, UCL are working on taking this further to a coupled model of Martian thermosphere and aurora.

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Example 2: UCL Magnetodisc model

What is it ? A model which calculates self-consistent magnetic field structure and plasma distributions for a `disc-like’, axisymmetric, rotating magnetosphere. Used for studies of magnetospheric structure at Saturn and Jupiter (giant rapid rotators) e.g. Achilleos, Guio and Arridge (MNRAS, 2010), Achilleos et al (GRL, 2010)

Giant Planet Magnetospheres

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• Present disc model assumes a fixed profile of plasma rotation (angular velocity M) versus radial distance.

• New configuration couples disc B-field model to an independent solver of plasma M

UCL Magnetodisc Model

M Solver

B Field Profile in Plasmadisc

M profile needed to

update force balance, re-compute B Field

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• New configuration links two independent Matlab codes on different nodes in a local network through a simple Java class using IP Sockets. Java code could be provided as part of a ‘JRA3 report’.

• We could do a similar exercise for the magnetopause field model - at present we use average value from the formulae of Alexeev et al (Ann. Geo. 2005) (Catalogue entry ?)

UCL Magnetodisc Model

M Solver

B Field Profile in Plasmadisc

M profile needed to

update force balance, re-compute B Field

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Example 3: MarTIM: Mars Thermosphere and Ionosphere GCM

MarTIM Description• General Circulation Model

• Finite difference solutions to the coupled non-linear Navier-Stokes equations of continuity and momentum as well as an energy equation.

• Calculations conducted on a co-rotating grid of variable size in the pressure coordinate system.

• Extends vertically from 0.883 Pa lower boundary (~60km) to 3.7x10-8 Pa (~200-350km).

• Evaluates main sources of solar forcing (EUV/UV and IR absorption).

• Evaluates principal cooling rate from the CO2 15-μm radiative band.

• Self-consistently determines the diffusion and advection of four gas species (CO2, N2, CO and O).

• Three dimensional variation in neutral atmospheric temperature, wind velocities and composition.

http://europlanet-ri.eu

Recent MarTIM DevelopmentNicholson, W.P., 2011, PhD Thesis, University College

London ftp://ftp.star.ucl.ac.uk/william

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MarTIM Results: Highlights

Nicholson, W.P., 2011, PhD Thesis, University College London ftp://ftp.star.ucl.ac.uk/william

• Nightside vertical temperature structure MarTIM versus SPICAM derived results.• Solid lines bin-average coupled MarTIM+MCD results, SMIN (low dust), SMED (annual average dust), SMAX (high dust).• Dashed lines bin-averaged SPICAM data, assuming upper atmosphere temperatures: 100 K, 175 K, 250 K.

http://europlanet-ri.eu

MarTIM + TransMars: The New Ionosphere SubroutineCouple MarTIM to a 1D kinetic model (TransMars,

Laboratoire de Planétologie, Université Joseph Fourier, Grenoble).

Calculate the degradation in energy of propagating suprathermal (primary) electrons and the production rate of secondary electrons.

Suprathermal electron sources photoelectronsSee e.g. Lilensten et al., 2005, Gronoff et al., 2007,

2008

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CO2+ Production efficiency (secondary / primary production) as a function of

altitude, solar zenith angle, season and solar conditions.

Production efficiency versus altitude Altitude of maximum efficiencydz(Χ) = zPeak,χ=0 + αcos(Χ) – β(cos(Χ))1/2 + ϒ

α=15, β=40, ϒ=25See Nicholson et al., 2009 (doi:10.1111/j.1365-2966.2009.15463.x)

Χ=0o

Χ=90o

Altitude of maximum primary CO2+ production

Altitude of maximum secondary CO2+ production

Altitude of maximum CO2+ production efficiency

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Model User Input Example in the Europlanet JRA3 Interactive Catalogue (only a ‘stub’ at present!)

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A reminder of what JRA3 activities may foster in the long term:My feeling is that these are beyond the scope of Europlanet (not enough resource) but they may

indicate ‘where we are headed’ if we follow some of the more simple ideas.

Example A: A time-dependent MHD model of Jovian or Kronian plasmadisc to couple to the appropriate atmospheric GCMs, to study transient auroral response.

Example B: A time- and space-dependent model of auroral precipitation associated with the Io-Jupiter ‘current circuit’, to investigate the nature of wind systems driven by such a localised source of auroral energy input.

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Catalogue-Linked Active Web Apps:•These are:

1. The H3+ cooling function calculator (code from S. Miller) JRA3T32. The VoiSe image segmentation tool (code from P. Guio) JRA3T4

•Web apps migrated to new webserver (beginning 2011) and are now live athttp://astroweb.projects.phys.ucl.ac.uk/europlanetjra3/

•Entries for these web apps have been update on the JRA3 catalogue.

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Input parameters

Input files?

Job detailsJob details

Results?

JobsQueue JobQueue Job

Process Job

Process Job

Results/Notification by Email

Job details

Validate Parameters

Validate Parameters

Process diagram for each web app:

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Technologies used for Web Apps

•Web Interface and Parameter Validation• Django web framework for Python

•Job Queuing System/Broker• RabbitMQ Advanced Message Queuing Protocol (AMQP) compliant

message queuing system

•Job Processing• Django-Celery asynchronous task queue/job queue.

•Database for Job Detail Storage• MySQL

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Upcoming Web Apps

• MarTIM• Mars Thermosphere and Ionosphere Model• 3D general circulation model of the Martian middle and upper

atmosphere from 0.883 to 9.9×10−8 Pa.• Developed by Will Nicholson• Possible coupling to TransMars

•UCL Magnetodisc Model• Described earlier…• A library of disc model outputs for community use to be placed in the

Catalog.

http://europlanet-ri.eu

Next steps? Action for all JRA3 Modellers: Whose work is relevant to what you are trying to achieve ? Are they in

the catalog - would they be willing to have an entry in the catalog ? The examples shown here illustrate the need in some areas of planetary science for progress by

‘coupling models’, even at a very basic level - e.g. GCMs as ‘testbeds’ for auroral profiles There may also be a possibility that we could provide force-balance models for theoretical models of

exoplanet discs (e.g. work by Khodachenko et al) Keep it simple, keep it realistic, make it a part of what you would ‘naturally’ want to do in your

own research programme Role of IDIS ? Enough material from UCL already (?) to compile a report of deliverables ?