In this study, the Fast On-Orbit Recording of Transient Events (FORTE) derived TEC variabilities on a diurnal cycle, seasonal cycle, 11-year solar cycle, and 27-day solar cycle are compared with the TEC estimates from the Los Alamos ionospheric transfer function implemented with the International Reference Ionosphere model, the GPS-derived TEC maps from NOAA, the GPS measurements made at Los Alamos, and the ionosonde critical frequency data at the closest station, Boulder, Colorado. The results show good agreement on average (monthly, annual, or multiyear means) in TEC variability at Los Alamos between the various data sources with relative RMS errors of about 5--10%. The results also show RMS errors larger than 30% for point-to-point comparisons, with the most significant errors found during high solar activity years, during summer seasons, and during strong geomagnetic storm conditions. This comparative study suggests that the FORTE-derived TECs combined with other TEC sources can help to better understand the TEC variability at Los Alamos in providing more accurate time-dependent site TECs than those derived from a single source or extrapolated from global model predictions.