First Results From the Ionospheric Extension of WACCM‐X During the Deep Solar Minimum Year of 2008

Abstract

New ionosphere and electrodynamics modules have been incorporated in the thermosphere and ionosphere eXtension of the Whole Atmosphere Community Climate Model (WACCM‐X), in order to self‐consistently simulate the coupled atmosphere‐ionosphere system. The first specified dynamics WACCM‐X v.2.0 results are compared with several data sets, and with the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model (TIE‐GCM), during the deep solar minimum year. Comparisons with Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite of temperature and zonal wind in the lower thermosphere show that WACCM‐X reproduces the seasonal variability of tides remarkably well, including the migrating diurnal and semidiurnal components and the nonmigrating diurnal eastward propagating zonal wavenumber 3 component. There is overall agreement between WACCM‐X, TIE‐GCM, and vertical drifts observed by the Communication/Navigation Outage Forecast System (C/NOFS) satellite over the magnetic equator, but apparent discrepancies also exist. Both model results are dominated by diurnal variations, while C/NOFS observed vertical plasma drifts exhibit strong temporal variations. The climatological features of ionospheric peak densities and heights (NmF2 and hmF2) from WACCM‐X are in general agreement with the results derived from Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) data, although the WACCM‐X predicted NmF2 values are smaller, and the equatorial ionization anomaly crests are closer to the magnetic equator compared to COSMIC and ionosonde observations. This may result from the excessive mixing in the lower thermosphere due to the gravity wave parameterization. These data‐model comparisons demonstrate that WACCM‐X can capture the dynamic behavior of the coupled atmosphere and ionosphere in a climatological sense.

A Comparison of Quiet Time Thermospheric Winds Between FPI Observations and Model Calculations

“…Without ion drag, the wind circulation is much stronger and the day‐to‐night temperature difference is smaller. Recently, Liu et al () compared TIEGCM simulated ionospheric F 2 peak electron densities ( N m F 2 ) with COSMIC (the Constellation Observing System for Meteorology, Ionosphere, and Climate) observations and found that TIEGCM simulated N m F 2 values are significantly smaller than the observations during both day and night during the June solstice, consistent with other model‐data comparison studies (e.g., Lei et al, ; Qian et al, ). Thus, TIEGCM may underestimate the ion drag effect due to relatively low modeled N m F 2 values and produce larger winds than observations indicate in the summer.…”

“…Without ion drag, the wind circulation is much stronger and the day-to-night temperature difference is smaller. Recently, Liu et al (2018) compared TIEGCM simulated ionospheric F 2 peak electron densities (N m F 2 ) with COSMIC (the Constellation Observing System for Meteorology, Ionosphere, and Climate) observations and found that TIEGCM simulated N m F 2 values are significantly smaller than the observations during both day and night during the June solstice, consistent with other model-data comparison studies (e.g., Lei On the other hand, in the zonal direction, we find that TIEGCM-modeled WE winds in general have a larger speed at night at three stations, and that the reversal of wind direction from eastward to westward occurs at an earlier local time than the observed zonal winds from about March to August at XL and KL stations. This is consistent with overestimates of the equatorial meridional wind magnitude by the model in the same months.…”

The Effects of IMF Bz Periodic Oscillations on Thermospheric Meridional Winds

“…Because at night, there is no significant ion production and molecular recombination is faster at low pressure levels (lower altitudes); the F 2 layer occurs at higher altitudes than during the daytime. Furthermore, the hmF 2 in the winter hemisphere is much lower than that in the summer hemisphere (Liu, Liu, Wang, et al, ). The peaks in the winter hemisphere disappear faster than that in the summer hemisphere (Abur‐Robb & Windle, ).…”

Thermospheric Composition O/N Response to an Altered Meridional Mean Circulation During Sudden Stratospheric Warmings Observed by GOLD

“…The WACCM‐X is a whole atmosphere model extending from the surface to the upper thermosphere (4.1 hPa, 500–700 km) and includes necessary chemical, dynamical, and physical processes to model the whole atmosphere system. For a detailed description and validation of WACCM‐X, the reader is referred to Liu et al (, ). Simulations were performed as a free‐running climate simulation and are thus not representative of any specific year.…”