World Meteorological Organization
WMO OMM
Working together in weather, climate and water
ICTSW-4 Doc 9.3.(1)
Space-based instrument categorization and evaluation
Required space weather variables and applicable layers in “OSCAR”
Jérôme Lafeuille
WMO Space Programme Office
WMO
www.wmo.int/sat
WMO OMM
Issues regarding the definition of space
weather variables and « layers »
• Type and list of variables
• Variables definitions and units
• Relevant « layers » and « coverage » for the
outer space domain
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Space Weather variables
WMO OMM
• ICTSW has defined 31 variables in 3 space weather themes :
– Ionospheric disturbances (e.g. Ionospheric scintillation)
– Space energetic particles (e.g. Proton flux density energy spectrum)
– Solar and interplanetary (e.g. Solar H-alpha image)
• Variables recorded under other themes
– Basic atmospheric: Wind and Density in thermosphere
– Solid Earth : Vector magnetic field
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WMO OMM
Issues with the type of variables (1)
• Variables are ideally the physical quantities needed to
understand/ model the environment
– E.g. magnetic field, radiative flux, velocity, density profile…
• Clearly defined
• Expressed in SI units
• Technology-free:
not pre-judging
any measurement
technique
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WMO OMM
Issues with the type of variables (2)
• Most of the Solar imagery variables do not meet these conditions
• A number of spectral bands:
– Solar Gamma-ray image, Solar X-Ray image, Solar EUV image, Solar UV image,
Solar VIS image, Solar Lyman-α image, Solar Ca II-K image, Solar H- α image,
Solar white light image….
• Are they all necessary or can measurements in some bands be
substituted by other bands ?
– High impact on the « Gap analysis »
• Are they the ultimate information needed to understand/model the solar
processes, or only proxy for e.g. detecting solar flares, active regions ?
– Possible confusion between measurements (image in certain bands) and
required information (e.g., detection of solar flares..)
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WMO OMM
Issues with the type of variables (3)
• Similar questions for ionospheric variables
– foEs, foF2, h’F, hmF2, h’P (spread F)
• Some of the variables are:
– complex: Spread F (h´P) « Vertical thickness of highly structured ion density in the
F-region of the ionosphere”
– linked with technology : FoEs « The highest ordinary-wave frequency reflected back
from a sporadic E layer and observed by an ionosonde”
• Can we instead define a requirement for a technology-free, physical
quantity to understand/model the ionosphere and derive these products?
– E.g., Electron density profile, Ion density profile, Refractivity index ?
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Issues with the list of variables
WMO OMM
• Current approach for imagery leads to a large number of variables
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–
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One for each spectral band, because instruments measure all these bands
Assumes a strict definition of the spectral bands
Shall we distinguish in each band: Flux, Image, Spectrum, Spectrum image?
In addition to Solar, Corona, Heliospheric and Aurora imagery, do we need
to consider other imagery ?
• « Vector magnetic field »
– Should it be renamed as « Vector Geomagnetic field » to avoid confusion
with Interplanetary and Solar magnetic fields?
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Issues with definitions and units
WMO OMM
• Use of SI units whenever possible
– E.g. replace (erg.cm-2 .s-1) by (mW.m-2 )
• Solar flux (γ-Ray, X-ray, EUV, UV, or VIS flux) in W/m2
– « Flux » or « Flux density » ? Could be clarified in the definition
– Same remark for « flux energy spectrum » vs « flux energy density
spectrum »
• [particle] flux density and [particle] flux density spectrum
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E.g. protons, electrons, heavy ions
Variable expressed in [particle]/area/time/solid angle
Unlike radiative flux density, refers to a solid angle around a given direction
Directional aspect should be clarified in the definition
What is actually required: 2.π average or directional information ?
(e.g. GOES Proton flux show major differences according to E-W direction )
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New variables – if we keep the current scheme !
WMO OMM
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Solar VIS flux, Solar VIS image, Solar VIS flux energy spectrum, Solar VIS flux energy spectrum
image, Solar UV flux energy spectrum, Solar UV flux energy spectrum image, Solar UV flux, Solar
UV image, Solar Lyman-alpha flux, Solar Lyman-alpha image, Solar X-ray flux energy spectrum,
Solar X-ray flux energy spectrum image, Solar gamma-ray flux energy spectrum, Solar gamma-ray
flux, Solar EUV flux energy spectrum, Solar EUV flux energy spectrum image ,
NIR flux, NIR image, SWIR flux, SWIR image, VIS flux energy spectrum, VIS flux energy spectrum
image, VIS flux, VIS image, UV flux energy spectrum, UV flux energy spectrum image, UV flux,
UV image, EUV flux energy spectrum, EUV flux energy spectrum image, EUV flux, EUV image, Xray flux, X-ray image, X-ray flux energy spectrum, X-ray flux energy spectrum image, Gamma-ray
flux’ Gamma-ray flux energy spectrum ,
Cosmic-ray flux density, Cosmic-ray flux density energy and mass spectrum, Neutron flux density
energy spectrum, Neutron flux density, Alpha-particle flux density energy spectrum, Alpha-particle
flux density,
Heavy ion flux density energy and mass spectrum image, Heavy ion flux density, Heavy ion flux
density image, Nuclei flux density energy and mass spectrum, Nuclei flux density energy and
mass spectrum image, Nuclei flux density, Nuclei flux density image, Electron flux density energy
spectrum image, Electron flux density, Electron flux density image
Electrostatic charge, Radio-waves, Electron flux density energy spectrum image, Electron flux
density, Electron flux density image
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WMO OMM
Applicable domain for a requirement:
layers and coverage
• « Layer » and « Coverage » refer to the vertical and
horizontal dimensions respectively
– Can be understood as « distance to Earth centre » and
« other dimensions »
• « Layer » are needed when
– Variable is likely to change along the vertical
– Requirement (uncertainty) may change as well.
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WMO OMM
Proposed new layer/coverage scheme
• Layers in Outer space domain
– Sun (?), Earth-Sun, GEO, MEO, LEO, Ionosphere
• Layers in Atmospheric domain
– High-thermosphere, Low-thermosphere, Near surface
• « Horizontal Coverage » to account for specific regions
such as:
– L1, L4/L5, polar regions, Sun-side, Shadow-side
– Magnetosphere ?
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