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Thermospheric winds and temperatures must be correctly specified to understand the impacts of lower atmosphere processes on the upper atmosphere and to measure the global effects of high-latitude magnetospheric processes. Fabry-Perot interferometers can estimate these parameters by measuring the characteristic 630.0 nm emission that is produced at around 250 km altitude. These sophisticated instruments exist at only a few locations globally, so models are often employed to provide wind and temperature estimates elsewhere. This study is composed of two parts. First, observing system simulation experiments estimate the accuracy of Fabry-Perot interferometer observations using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) and the Whole Atmosphere Community Climate Model eXtended (WACCM-X). Atmospheric observational error sources are found to be very small across two test periods (September 2000 and September 2010) and using two different “truth” models. The largest magnitude wind observation error is found to be 16.9 m/s, root-mean-square errors are 2.3 m/s, and the bias is 0.9 m/s. The largest-magnitude temperature observation error is found to be 63.7 K, root-mean-square errors over the test period are 6.7 K, and the bias is 2.8 K. Modeled redline emission altitudes vary by over 100 km, far more than was expected. Second, several models (TIEGCM, WACCM-X, the Horizontal Wind Model, and the Mass Spectrometer Incoherent Scatter model) are assessed using interferometer winds and temperatures from Cariri and Cajazeiras, Brazil, as ground truth. In the best cases, the models reproduce wind variability without systematic biases but show no ability to predict instantaneous values, although temperatures are modeled more accurately.

[1] A new technique is presented for the incorporation of ionosonde observations into GPS ionospheric tomography. This approach greatly improves the vertical resolution of the images when using independent incoherent scatter radar observations as ground truth, addressing a traditional weakness of tomographic techniques. Ionosonde observations are used to set vertical basis functions adaptively within the inversion as well as providing electron density information for direct assimilation. The technique also improves slant total electron content (TEC) accuracy in the vicinity of the ionosonde. An experiment was performed in the equatorial region of South America as a 6-day case study due to the availability of incoherent scatter and ionosonde data during this period. Preliminary results were validated with the Jicamarca incoherent scatter radar and independent GPS slant TEC observations. Using the incoherent scatter radar as ground truth for the vertical profile, the new technique reduces mean NmF2 error to −0.07 × 1011 electrons/m3 compared with 0.27 × 1011 electrons/m3 in a control run with no ionosonde data, while root-mean square error is now 0.5 × 1011 electrons/m3 compared with 1.0 × 1011 electrons/m3 in the control. The new technique also results in 0.1 km mean error in hmF2, compared with −3.9 km in the control, while root-mean square hmF2 error is around 40 km in both cases. Using independent slant TEC observations, the mean error is −0.36 TECU compared with 0.64 TECU in the control run, while root-mean square error is 3.55 TECU down from 4.02 TECU, suggesting the new technique also improves TEC values.