Dear Roger Thanks for your proposals and the useful background. I agree that these quantities should have standard names. I have some suggestions:
> standard name electrical potential gradient I suggest this should have "in_air" suffixed since CF stdnames apply to all domains of geophysics. Also, it needs to indicate its sign. If it's positive, does that mean the + is above and - below, or vice-versa? CF stdnames always include an explicit sign convention when relevant. If you need both conventions we can define two names. It should perhaps include "vertical" too but if the sign convention implies it's vertical that wouldn't be needed. > standard name vertical component of the conduction current density Again, "in_air" and the sign convention are needed, and "electrical" as well, but "component of the" can be omitted, as in many other component names e.g. upward_heat_flux_in_air, eastward_sea_ice_velocity. > standard name positive electrical conductivity > standard name upward negative electrical conductivity Again we need "in_air". These ones are scalars, I think, with no direction, so I don't understand why the second one says "upward". They should have the same form anyway. If I understand your description correctly, CF-like names would be electrical_conductivity_of_air_due_to_positive_ions electrical_conductivity_of_air_due_to_negative_ions Is that the right meaning? You give variable names and long_names too, but CF doesn't standardise these. Best wishes Jonathan On Fri, Aug 05, 2016 at 08:15:38AM +0000, Roger Brugge wrote: > Date: Fri, 5 Aug 2016 08:15:38 +0000 > From: Roger Brugge <[email protected]> > To: "[email protected]" <[email protected]> > Subject: [CF-metadata] Atmospheric electrical measurements > > Some proposed new CF standard variable names for electrical properties of the > atmosphere > > On behalf of the members of GLOCAEM > (http://gtr.rcuk.ac.uk/projects?ref=NE/N013689/1) I would like to propose > four new variables for the CF naming conventions, relating to the electrical > properties of the atmosphere. > > Each of these can be measured/modelled at any height of the atmosphere but as > they are often measured at near-ground level I have also included a ‘close to > the ground’ version with the ending ‘s’ in each case. > > From: > https://www.ngdc.noaa.gov/stp/space-weather/online-publications/miscellaneous/afrl_publications/handbook_1985/Chptr20.pdf > > Electric fields, currents, and conductivities as well positive and negative > ions of greatly varying size and composition constitute the principal > electrical properties of the atmosphere in fair weather. Air mass motions, > pressure systems, winds, turbulence, temperature, and water vapour > distributions have an important influence on the electrical properties in the > troposphere through their control over the distributions of charged and > uncharged aerosols and radioactive particles of terrestrial origin. These > influences are greatest in the atmospheric exchange layer which is generally > restricted to 2.5 km above the earth's surface. In the altitude region 30 to > 90 km there is a transition from classical concepts of atmospheric > electricity to the phenomena of ionospheric physics chiefly because of the > changing atmospheric composition and increasing mean free path resulting in > an increase in the concentration of free electrons. Recent studies have shown > that the ionosphere, with its relatively high conductivity, can no longer be > regarded as the upper bound for atmospheric electrical processes. The exact > nature of electrical coupling to the ionospheric and magnetospheric regions > is currently under investigation. > > Good references for these quantities are D.R. McGorman and W.D. Rust, The > Electrical Nature of Storms, Oxford University Press, Oxford, 1998 and E.P > Krider et al The Earth’s Electrical Environment, Studies in Geophysics, > National Academy Press, Washington, 1986 > http://www.nap.edu/openbook.php?record_id=898&page=R1 > but the role and importance of each may be summarised as follows: > > 1. Electrical potential gradient. As a result of charge separation in > disturbed weather regions and ionization sources in the atmosphere (including > cosmic radiation) there exists a vertical electric potential gradient through > the atmosphere. In fair weather conditions remote from pollution, this varies > in a diurnal fashion (the so-called “Carnegie curve”). In disturbed weather > it becomes highly variable. > > 2. Vertical conduction current density. The potential gradient causes > charged particles (ions) in the atmosphere to flow vertically. At the surface > this is known as the air-Earth current. > > 3. positive (negative) electrical conductivity of the atmosphere. This is > the polar (positive or negative) electrical conductivity resulting from > positive (negative) small ions in atmospheric air. The conductivity is the > product of the ion concentration and the ion mobility, and the elementary > charge. > > Variable 1: > long name vertical component of the atmospheric electrical > potential gradient > variable name pg (pgs when measured at station height close to the > ground) > standard name electrical potential gradient > unit_name V/m > note The potential gradient is considered positive in fair > weather. (The vertical component of the electric field is negative in fair > weather.) > > Variable 2: > long name vertical conduction current density > variable name jcz (jczss when measured at station height close to > the ground) > standard name vertical component of the conduction current density > unit_name pA/m2 > note jczss is known as the air-Earth current at the surface > > Variable 3: > long name positive electrical conductivity of the atmosphere > variable name sigp (sigps when measured at station height close to > the ground) > standard name positive electrical conductivity > unit_name fS/m > note S denotes Sievert > > Variable 4 > long name negative electrical conductivity of the atmosphere > variable name sign (signs when measured at station height close to > the ground) > standard name upward negative electrical conductivity > unit_name fS/m > note S denotes Sievert > > I'd be interested in any comments, > > Regards > Roger Brugge > University of Reading > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
