### Physical Variables written by CTIP simulations

The**coordinate system**consists of

- Longitude
**Lon**with**positive**vector components meaning**eastward**,

- Latitude
**Lat**from -90 at the south pole to 90 at the north pole with**positive**being**northward**,

- pressure level
**IP**or height**H**in km.

**Vector (arrow) plots**of the velocities only make sense as:

**vertical cuts**(meridional or at constant-latitude) if**UseHeight**is selected,

**synoptic maps**of velocity vectors (over local time and latitude) if plotted at**constant height**(not constant pressure level IP).

**basic plasma and electrodynamic field variables in 3D**are:

**H (height)**in [km] corresponding to pressure level number**IP**

The height of a pressure level varies spatially and with time. Heights covered start at about 80 km (**IP**=0) and reach a few hundred km above ground (the maximum found for**IP**=14, the top layer, is typically between 450 km and 1000 km).

The height can be used as an alternative 3rd coordinate for plotting.- Particle number density
**N**in [m^{-3}] with species identifier (after the "_"):**e**: electrons,**O**: oxygen ions,**N2**: nitrogen molecules,**O2**: oxygen molecules.

- Neutral gas temperature
**T_n**in [K]. - Mean molecular mass
**Rmt**in [amu]. - Hall and Pedersen conductivities
**sigma_H**,**sigma_P**in [mho/m]. - Neutral gas velocity
**Vn**in [m/s] with its three components

**Vn_Lat**(meridional; CTIP name "V_x"),

**Vn_Lon**(zonal, longitudinal; CTIP name "V_y") and

**Vn_IP**(vertical, radial; CTIP name "V_z"). - Plasma (ion) velocity
**Vi**in [m/s] with its components

**Vi_Lat**("Vi_x"),

**Vi_Lon**("Vi_y").

**Vi_IP**("Vi_z") is missing in the model output and assumed to be zero for vector arrow plots. **sigmaP**,**sigmaH**: Pedersen and Hall conductivities [S/m],

**Height-integrated quantities in 3D data**

available at each position in local time and latitude (obtained from 3D CTIP variables above)

**NmF2**: maximum electron density**N_e**in [m^{-3}] in the vertical profile**HmF2**: height in [km] of the maximum of**N_e**(see**NmF2**)**TEC,**total electron content, integrated over altitudes between 80 and 2000 km [TECU=10electrons/m ^{2}]**O/N2**: ratio of N_O and N_N2 in the vertical column. The ratio is calculated from the pressure level where**SH*N_N2=10**with^{21}m^{-2}**SH=k_B T_n/(g*m(N**being the scale height of the N_{2}))_{2}gas species (m(N_{2})=28 amu). The O-column density is obtained by interpolation at this pressure level using model outputs at pressure levels 8 and 9.

Last updated: Sept. 10, 2010 - Lutz Rastätter