The three-dimensional global numerical model CHARM-I: The incorporation of processes in the ionospheric D-region

Abstract

We describe the three dimensional numerical global photochemical model CHARM I (CHemical Atmospheric Research Model with Ions) and the results of numerical calculations of global distributions of neutral and charged atmospheric trace gases (in the height range of up to 90 km), such as ozone, nitrogen oxides, electrons, and positive and negative ions. This model is an improved version of the CHARM three dimensional photochemical model of neutral components with additional reactions with the involvement of ions (a total of 200 photochemical reactions). The model incorporates UV radiation fluxes on the Lyman α line and galactic cosmic rays as ionizing factors. The neutral components are calculated with the method of "chemical families" and the concentrations of charged components are calculated by the electroneutrality condition at each time step.The spatial transport of chemically active species is described in the model by the Prather scheme. The developed model makes it also possible to take into account solar flares and particle pre cipitations in the ionospheric D region.

Using the World Wide Lightning Location Network (WWLLN) to Study Very Low Frequency Transmission in the Earth‐Ionosphere Waveguide: 1. Comparison With a Full‐Wave Model

“…To a first-order approximation, the daytime ionization state of the D-region is most controlled by the local solar zenith angle. But beyond that approximation, there are important complications due to the dependence of the photochemistry on the global atmospheric circulation pattern (Krivolutsky, Cherepanova, V'yushkova, & Repnev, 2015;Kulyamin & Dymnikov, 2015;Turco & Sechrist, 1972a, 1972b. This spatially and temporally modulates the availability of readily ionizable species, foremost of which is the molecule NO.…”

“…This spatially and temporally modulates the availability of readily ionizable species, foremost of which is the molecule NO. According to both of the two modern numerical coupled D-region/global circulation models (Krivolutsky et al, 2015;…”

“…This spatially and temporally modulates the availability of readily ionizable species, foremost of which is the molecule NO. According to both of the two modern numerical coupled D‐region/global circulation models (Krivolutsky et al., 2015; Kulyamin & Dymnikov, 2015), the departures from a simple solar‐zenith‐angle control are most apparent at low latitudes and at the latitude of the sub‐solar point.…”

“…This will allow the model to focus on periods of rapid excursion, when there is the most reason to attribute control to the solar‐zenith‐angle changes occurring along the paths, but to avoid modeling the residual (and smaller) variations observed during pure‐day or pure‐night conditions. Logically, the latter are more likely related to complicated atmospheric‐circulation effects on the photochemistry (Krivolutsky et al., 2015; Kulyamin & Dymnikov, 2015) than they are simply to rapid changes of the solar illumination.…”

WACCM‐D—Whole Atmosphere Community Climate Model with D‐region ion chemistry

“…While the HNO 3 problem can be fixed with an improved parameterization during strong precipitation events [ Verronen and Lehmann , ], this parameterization cannot reproduce the longer‐term effects of ion chemistry on reactive nitrogen partitioning, ozone, and dynamics of the middle atmosphere [ Kvissel et al ., ]. These issues have led to ion chemistry experiments in global models [ Egorova et al ., ; Krivolutsky et al ., ], and prompted us to develop WACCM‐D, a variant of the Whole Atmosphere Community Climate Model (for a description of the standard WACCM model, see Marsh et al . [] and references therein), which incorporates a set of D‐region ion chemistry with the aim to produce the observed EPP effects in the mesosphere and upper stratosphere.…”