Research

Particle transport

Auroral electrons

Transport equation solved for electron flux as function of altitude, energy, and pitch angle.   Electrons are introduced at the upper boundary via precipitation as a function of energy and angle.  They can also be introduced internally via ionization by auroral protons and hydrogen atoms.   Energy range begins at 1 eV and extends to 10's of keV.   Solution is a composite of degraded primary electrons and secondary electrons.   Solution obtained by eigenvalue technique.

Auroral protons and hydrogen atoms

Coupled transport equations solved for proton and hydrogen atom fluxes as function of altitude, energy, and pitch angle.   Energy range goes from sub-keV energies to 10's of keV.

Photoelectrons

Transport equation solved for electron flux as function of altitude, energy, and pitch angle.   Source electrons are introduced internally via photoionization.   Energy range begins at 1 eV and extends to beyond 1 keV.   Solution obtained by Feautrier technique.

Photon transport

Equation of radiative transfer solved using Gladstone's Redister model contained in CPI's AURIC model.   Multiple scattering calculations can be performed for either partial or complete frequency redistribution.   Examples of emission features treated by the model are OI 130.4 nm, OI 135.6 nm, OII 83.4 nm, and NI 120.0 nm.

Photochemistry

Coupled non-linear rate equations solved for chemically active neutral species and ions.   Models are available for dayside and auroral applications.

Spectroscopy

Spectral radiances may be calculated for the key lines and molecular band systems from the far ultraviolet to the near infrared using CPI's AURIC model (dayglow and nightglow) and auroral model.

Data assimilation techniques

CPI has developed algorithms that apply the optimal interpolation (OI) formalism to the problem of data assimilation.   These algorithms have been used to assimilate irregularly sampled data sets of stratospheric trace gases (e.g., ozone) from multiple satellites into gridded, three-dimensional instrument-independent data sets.

Data simulations

Optical sensor data recorded on-board satellites may be simulated using CPI's first principles models for either measurements from a specific location or for extended observing periods (e.g., over complete obits).   Simulations for extended observing periods utilize orbit models and take into consideration details in viewing geometries.   Full orbit raw data simulations have been performed, e.g., for the DMSP SSUSI and SSULI instruments.

Distributed computing

Over the course of the last decade CPI has developed several models that employ the power of distributed computing.   Earlier applications of distributed computing utilized the Parallel Virtual Machine (PVM) technology to develop a fast limb radiance code that distributed viewing vectors on available processing nodes.   More recent applications employ the power of the Common Object Request Broker Architecture (CORBA) to develop component-based architectures for battlespace environment simulations as well as first-principles photochemistry and particle transport phenomenology models applicable to any planetary atmosphere.

Inversion algorithms

CPI has developed very general retrieval algorithms based on a generic implementation of the Optimal Estimation constrained linear inversion technique.   These algorithms have been successfully employed in the analysis of atmospheric remote sensing data from a number of satellite-based platforms.

Ray tracing

Two and three dimensional ray tracing models are used to determine ionospheric effects on signals originating from ground level.   Effects include bending, time delay, and frequency shifts (i.e.  ionospheric Doppler effects).   Applications are to radar tracking of space objects and geolocation.