Space-based data provides coverage and vertical information complementary to ground-based data.   [LEFT-upper] GAIM ionosphere with SSULI data along 210°E longitude for 19 Apr 2012 at 0645UT; [LEFT-lower] GAIM ionosphere without SSULI data; [RIGHT-upper] Location of GPS and SSULI data; [RIGHT-lower] Difference between the LEFT-upper and LEFT-lower GAIM ionospheres.
Space-based data provides coverage and vertical information complementary to ground-based data. [LEFT-upper] GAIM ionosphere with SSULI data along 210°E longitude for 19 Apr 2012 at 0645UT; [LEFT-lower] GAIM ionosphere without SSULI data; [RIGHT-upper] Location of GPS and SSULI data; [RIGHT-lower] Difference between the LEFT-upper and LEFT-lower GAIM ionospheres.

Objective
NRL SSD has been the technical lead for the DoD operational Global Assimilation of Ionospheric Measurements (GAIM) program since its inception by ONR in 1998. The assimilative model, which was developed by Utah State University, is the centerpiece of a large team effort which includes NRL, ONR, Air Force Weather Agency (AFWA), USAF Space and Missile Systems Center (SMC) Air Force Space Command (AFSPC), Johns Hopkins Applied Physics Laboratory (JHU/APL), the Aerospace Corporation, Northrop Grumman, NASA, and a wide-ranging User Community.

Approach
Technical: GAIM is based on a background physics model, the Ionospheric Forecast Model (IFM), which generates a climatological estimate of the ionosphere using near-real-time geophysical parameters. A Kalman filter and near-real-time ionospheric data are then used to perturb the climatological estimate in order to generate an accurate nowcast of the ionosphere that includes transient space weather phenomena. A global ionosphere is generated in a 15-minute cadence, from 90-1400 km. A 24-hour Forecast, in one-hour increments, is also generated each hour

Programmatic: Each new version of GAIM is transitioned from Utah State University to NRL SSD for computational testing and validation and verification while being transitioned for operational use at AFWA. New data types are evaluated for GAIM ingest, data impact studies are conducted, and operational metrics studies are provided for the US Air Force

Deliverable/Value/Accomplishment

  • Under NRL’s leadership, the GAIM program began as a Multidisciplinary University Research Initiative (MURI) in 1998 and transitioned to Initial Operational Capability (IOC ) at AFWA in February 2006. Since then, there have been many upgrades as the model has improved and new ionospheric data sets have been added for ingest
  • GAIM is the current state-of-the-art ionospheric operational model in the DoD. GAIM products, such as ionospheric nowcasts and forecasts, are used for higher-level applications such as HF communications and GPS positioning