Instruments:gcm

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Thermosphere Ionosphere General Circulation Model (TIGCM)

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(for new TIE-GCM and TIME-GCM runs for 365 days in 2002 using 10.7 cm flux and Kp as inputs, or with constant conditions of 18.3 GW auroral input and 53.8 kV potential drop for additional TIE-GCM runs in netCDF format)

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Description of Instrument/Model

The NCAR TIGCM models output neutral winds and temperature. Specific TIGCM results are shown for the storm of March 22, 1979. The other results are of generic runs with the TIGCM which are described in Fesen (1997, JASTP, 785).

The TIGCM model solves and saves 16 parameters: ht, Tn, un, vn, wn, N2, O2, O, N(4S), N(2D), NO, Te, Ti, Ne, O+, and O2+. The O+-O collision frequency was increased by a factor of 1.7 in the model over the laboratory value, as recommended by Burnside et al (1988, JGR, 8642) and Salah (1993, GRL, 1543).

The model has 36 latitudes between -87.5 and +87.5 degrees geographic every 5 degrees apart, 72 longitudes between -180 and +175 geographic every 5 degrees apart, and 25 pressure levels between 97.5 km and approximately 500 km.

This data set has interpolated (or extrapolated) values of the neutral zonal and meridional wind and neutral temperature at 22 heights between 100 and 500 km for all 36 latitudes at 24 longitudes every 15 degrees apart between -165 and +180 degrees. The diurnally reproducible results were saved for 25 UTs, and then harmonic analyses of these parameters were computed.

Eighteen generic runs were made in 1993 for solar minimum (1976, with an assumed solar flux (350) of 75) and solar maximum (1979 with an assumed solar flux of 195), for three seasons (days 80, 172, and 355), and for three levels of activity (5 GW + 30 kV, 11 GW + 60 kV, and 33 GW + 90 kV). The activity is based on the hemispheric power and the polar cap potential drop. The IMF By was assumed to be 0 nT in the parameterizations. The 1989 Forbes and Vial semidiurnal tides appropriate for March, June and December were put at the lower boundary (97 km). Another version of these runs was for 70W only.

The summary plots show the wind fields on the temperature over the globe at 300 and 140 km every 4 UT hours on March 22, 1979, and at 0 and 12 UT for the generic runs. Only the 60 kV case was plotted for the generic runs in solar minimum (sflux=75) and solar maximum (sflux=195) for March, June and December.

The tidal fields for the neutral temperature and neutral zonal and meridional wind are shown at 140 and 300 km for the generic runs as a function of longitude and latitude. The 4 plots show the mean and the 24, 12 and 8-hr tidal amplitudes. Only the 60 kV case was plotted for the generic runs in solar minimum (sflux=75) and solar maximum (sflux=195) for March, June and December. The Fesen (JASTP, 1997) reference shows the tidal variations also as a function of height and magnetic activity for 70W.

References for the model

Dickinson, R.E., E.C. Ridley, and R.G. Roble, A three-dimensional general circulation model of the thermosphere, J. Geophys. Res., 86, 1499-1512, 1981.
Roble, R.G., R.E. Dickinson, and E.C. Ridley, Global circulation and temperature structure of thermosphere with high-latitude plasma convection, J. Geophys. Res., 87, 1599-1614, 1982.
Roble, R.G., E.C. Ridley, A.D. Richmond, and R.E. Dickinson, A coupled thermosphere/ionosphere general circulation model, Geophys. Res. Lett., 15, 1325-1328, 1988.

Further references concerning tidal components of the model

Fesen, C. G., Geomagnetic activity effects on thermospheric tides: A compendium of theoretical predictions, J. Atmos. Solar-Terr. Phys., 59, 785-803, 1997.
Fesen, C. G., A. D. Richmond and R. G. Roble, Theoretical effects of geomagnetic activity on thermospheric tides, J. Geophys. Res., 98, 15599-15612, 1993.
Fesen, C. G., R. G. Roble, and E. C. Ridley, Thermospheric tides simulated by the National Center for Atmospheric Research Thermosphere-Ionosphere General Circulation Model at equinox, J. Geophys. Res., 98, 7805-7820, 1993.

Notes

  • Many of the data sets offered on this page are quite large and thus can take a few miniutes to download.

Summary Plots for the TIGCM Model Results for 22 March 1979

Summary Plots for the TIGCM Generic Model Results

Tidal

Non-Tidal

GSWM solar tides

Forbes-Vial Semidiurnal solar tides


-Revised 03 Nov 2003 by Barbara Emery