Objective: Conduct research to observe, understand, model, and forecast the geospace environment and its connections to its lower and upper boundaries, toward facilitating and advancing functional capabilities for the Navy/Marine Corps and other agencies.

S&T Status: Research in the development and deployment of space-based sensors that measure the thermosphere and
ionosphere; in application of theoretical, experimental, and HPC computational techniques to understand near-Earth dynamics to gain a predictive capability and mitigate environmental effects; and, in problem-centric tasking and fusion processing systems and analysis architectures for increased situational awareness.

For more information, please contact nrl.ssd.code7600@nrl.navy.mil.

Selected Research

Infrasound Propagation


  • Specify and understand how the natural variability of the atmosphere from minutes to days influences regional to long-range, low-frequency acoustic propagation.
  • Advance the fundamental understanding of acoustic propagation in the atmosphere.
  • Understand the influence of acoustic waves on the atmosphere and ionosphere.
  • Improve US national and international treaty organization capabilities to detect, locate, and characterize infrasound events of interest.
Empirical Modeling of the Upper Atmosphere: NRLMSISE-00, HWM07, and G2S

Measurement-based specification of the upper atmosphere system and its response to solar and lower atmospheric drivers. The upper atmosphere is operationally important because of the drag it exerts on low Earth orbit satellites, and because of its fundamental influence on the ionosphere.
These empirical models are key components of upper atmospheric research and operations for:

  • Specification and prediction of the environment;
  • Benchmark for calibrating and validating new measurements and measurement techniques;
  • Interpolation and extrapolation of data; and,
  • Initial and/or boundary condition for general circulation models.
Schematic depiction of the prediction ranges of various atmospheric models relevant for this work, plotted versus altitude (y) and predictive time scale (x). Prediction over this entire space is the long-term goal of the collaborative Earth System Prediction Capability (ESPC). NAVGEM: Towards a Ground-to-Space Navy Global Earth System Prediction Capability (ESPC)


  • To extend the Navy Global Environmental Model (NAVGEM), as the DoD’s bridge strategy to a future ESPC, from its current upper boundary at ~65 km altitude, to altitudes of ~100 km
  • Use the system to improve the skill and range of atmospheric forecasts, with an emphasis on deep coupling pathways affecting seasonal prediction (e.g. Arctic sea ice)
  • Transition new capabilities to the operational NAVGEM at Fleet Numerical Meteorology & Oceanography Center (FNMOC) if/where they yield improved skill or new Navy-relevant capabilities
Deep-Propagating Gravity-Wave Experiment (DEEPWAVE)


  • To understand, model and parameterize atmospheric gravity waves (GWs) by observing and characterizing them over their entire life cycle (0-100 km altitude) in localized “hotspot” regions identified in the satellite record.
  • Coordinate models, theory, and observations to maximize scientific insight into open questions concerning GW generation, propagation, breakdown and predictability that can in turn improve parameterizations of unresolved GW dynamics in global weather and climate prediction models.
Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER)

SHIMMER, the primary payload of STPSat-1 from March 2007 through October 2009, had four main objectives:

  1. Fly in space, for the first time, a monolithic Spatial Heterodyne Spectrometer (SHS) to increase the technical readiness level for this innovative optical technique
  2. Observe mesospheric OH (hydroxyl) on a global scale at all (daytime) local times to investigate atmos. photochemistry
  3. Observe Polar Mesospheric Clouds (PMCs) at the edge of their polar occurrence region
  4. Validate NOGAPS-ALPHA/ NAVGEM saturation modeling
Observed and modeled monthly mean global temperatures are compared in the top panel. The model combines ENSO, volcanic  aerosols, solar irradiance and anthropogenic effects.  (Lean and Rind 2009) Natural and Anthropogenic Influences on Climate, the Atmosphere and Ozone

Inform new Navy/DoD mandate (Task Force Climate Change) to incorporate climate change on seasonal and decadal time scales into future operational planning, using state-of-the-art global Earth-system modeling to:

  • Understand how the major natural and human induced climate forcings combine to yield net climate sensitivities and impact DoD operations, both globally and regionally
  • Define the range of geophysical variability of future climate states and their associated predictive uncertainties
  • Develop data bases of projected climate variability and associated statistics (e.g., frequency of regional extreme events) for upcoming decades in formats easily incorporated into future operational scenarios by DoD planners and decision makers
Global average mass density at 400 km (near the altitude of the ISS) . The density data were derived from the orbits of thousands of objects. Orbital Drag Studies of the Upper Atmosphere

Develop methods for extracting thermospheric density from orbital drag and understand the response of the thermosphere to solar and lower atmospheric influences.
The thermosphere (90-800 km) is the operating environment of spacecraft in low Earth orbit (LEO); the drag it exerts on LEO objects is the largest source of uncertainty for orbit determination and prediction. The thermosphere expands in response to heating by solar UV irradiance and magnetospheric energy and contracts when these energy inputs are low. Thermospheric density also depends strongly on dynamics, chemical composition, and cooling efficiency at altitudes of 90-150 km.

The BSI reflects radio signals, useful for applications like medium and long range wavelength comms and radar. This highly variable layer depends on external drivers such as solar forcing and lower atmospheric dynamics. Combining several atmospheric models that cover the various regions from ground thru the BSI enables better specification and forecasting. Bottomside Ionosphere Weather Modeling

Demonstrate and validate a high-performance computing atmospheric simulation capability that includes sufficient atmospheric modeling of the variability of the bottom-side ionosphere (BSI) at low to mid latitudes, for accurate numerical forecast of HF radio wave propagation through Earth’s atmosphere and ionosphere.

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. Global Assimilation of Ionospheric Measurements (GAIM)

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.

(Left) Airglow and aurora viewed from STS-39.  (Right) The gold-blanketed RAIDS experiment (top left) views the aft atmospheric The inset shows thermosphere temperatures and NRLMSISE-00 model predictions (red) derived from airglow. (Photos: NASA) Remote Atmospheric and Ionospheric Detection System (RAIDS)

The Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of three photometers, three spectrometers, and two spectrographs which collectively span the wavelength range 50-874 nm and passively measures Earth's naturally-occurring airglow. RAIDS operates from the International Space Station (ISS) to remotely sense the Earth's thermosphere and ionosphere by scanning and imaging the atmospheric limb.

Special Sensor Ultraviolet Limb Imager (SSULI)


  • Measurements provide scientific data supporting military and civil systems
  • Assists in predicting atmospheric drag effects on satellites and re-entry vehicles
  • Ionospheric data products ingested by DoD state-of-the-art assimilative space weather model, GAIM
  • New models of global electron density variation
  • First operational instrument of its kind
  • Provides new technique for remote sensing of Ionosphere and Thermosphere from space
Special Sensor Ultraviolet Limb Imager Ground Data Analysis Software (SSULI GDAS)

NRL SSD has developed advanced operational software for the DMSP SSULI UV instruments, the SSULI GDAS, that uses state-of-the-art sensor and atmospheric algorithms to generate near-real-time ionospheric and thermospheric space weather data products for DoD.

The GDAS generates Sensor Data Records (SDRs) and Environmental Data Records (EDRs) from SSULI observational limb scan data. The GDAS products are used operationally at the Air Force Weather Agency (AFWA) for ingest into assimilative space weather models such as GAIM and as standalone space situational awareness (SSA) products.

Exploded view of the SWATS sensor Winds Ions Neutrals Composition Suite (WINCS) / Small Wind And Temperature Spectrometer (SWATS)

Develop low size, weight, and power (SWaP) in-situ instrument suite capable of measuring neutral winds, neutral temperature, neutral composition, ion drifts, ion temperature, and ion composition. The sensor suite is also known as the Winds Ions Neutrals Composition Suite (WINCS).

PRESAGE: Quantifying and Reducing Space Collision Risk w/ Sun-Earth System Forecasting & Probabilistic Dynamics

Quickly assimilate tracking data of new orbiting space objects while simultaneously shrinking the error ellipsoids in order to create more room to operate in space. To do this we need to know where all satellites and debris are and where they will be for the next seven days.

Current capabilities are inadequate to monitor the space objects population to avoid collisions. E.g., current practice did not prevent the Iridium-Cosmos collision that increased space debris by 10%. (False alarms are also bad and avoidance maneuvers are both costly and risky.) The biggest obstacles to achieving effective collision avoidance are inaccurate prediction of Sun-Earth system dynamics and atmospheric drag, and current manually intensive techniques for assimilating tracking data.

LARADO concept (patent pending): a light sheet is formed by a collimated light source and a conic mirror. Objects passing through the sheet will scatter light that can be detected by a camera with a wide angle lens to determine the location and potentially size of the object. Serendipitously, the camera will also sense nearby illuminated objects outside the laser sheet. Laser-sheet Anomaly Resolution and Debris Observation (LARADO)

Develop and demonstrate an innovative concept to perform real-time, on-orbit, local object detection to provide damage attribution and Space Situational Awareness. NRL is not aware of any comparable system. Currently, on-orbit data of particle impacts is typically collected from the inspection of satellite surfaces that are brought back to Earth. This simple concept can be tailored to specific applications e.g. by using different sheet geometries and sheet intensities to effectively cover larger or smaller areas.

Integrating the Sun-Earth System (ISES) for the Operational Environment

Characterize and simulate multiple chains of physical processes that link the Sun-Earth system, to advance space science and enable Naval/Marine Corps and wider DoD operations to better account for, adapt to, and exploit operational impacts of the space environment due to electrons, ions and neutrals.

Left: Image of monolithic DASH interferometer; Right: Conceptual Design of a DASH space flight instrument. Doppler Asymmetric Spatial Heterodyne (DASH) Spectroscopy

The objective of the DASH development effort is to increase the TRL of the innovative DASH spatial heterodyne spectroscopy (SHS) technique for future space-based thermospheric wind observations. (NRL Patent 7,773,229)

High quality global thermospheric wind observations are currently not available, but are essential for improving orbit determination and comms, geopositioning, via ingest into models such as ISES.