New routine NLTE15μmCool-E v1.0 for calculating the non-local thermodynamic equilibrium (non-LTE) CO2 15 μm cooling in general circulation models (GCMs) of Earth’s atmosphere

Abstract

We present a new routine for calculating the non-local thermodynamic equilibrium (non-LTE) 15ĝ€¯μm CO2 cooling-heating of mesosphere and lower thermosphere in general circulation models. It uses the optimized models of the non-LTE in CO2 for day and night conditions and delivers cooling-heating with an error not exceeding 1ĝ€¯Kĝ€¯d-1 even for strong temperature disturbances. The routine uses the accelerated lambda iteration and opacity distribution function techniques for the exact solution of the non-LTE problem and is about 1000 times faster than the standard matrix and line-by-line solution. It has an interface for feedbacks from the model and is ready for implementation. It may use any quenching rate coefficient of the CO2(ν2)+O(3P) reaction, handles large variations in O(3P), and allows the user to vary the number of vibrational levels and bands to find a balance between the calculation speed and accuracy. The suggested routine can handle the broad variation in CO2 both below and above the current volume mixing ratio, up to 4000ĝ€¯ppmv. This allows the use of this routine for modeling Earth's ancient atmospheres and the climate changes caused by increasing CO2.