  Rocket exhaust plumes have been observed to cause large-scale depletions of
ionospheric plasmas ("ionospheric holes"). In the F-region, charge exchange
reactions occur between O^+ ions and exhaust species such as H$_2$O, H$_2$, and
CO$_2$ to form ions which then undergo rapid dissociative recombination. The
Global Ionosphere-Thermosphere Model (GITM) was extended to include these
chemical reactions and appropriate source terms to represent rocket exhaust
plumes. The resulting model was applied to ionospheric depletions resulting
from the launches of Jason-3 and FORMOSAT-5 on SpaceX Falcon 9 rockets from
Vandenberg Air Force Base. Outputs from the model were compared with GNSS,
ionosonde, and satellite Langmuir probe measurements. Simulation indicated that
the FORMOSAT-5 launch resulted in a far larger and longer-lived ionospheric
depletion than the Jason-3 launch, consistent with observations.
