92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012
New Operational Algorithms for Charged Particle Data From Low-Altitude Polar-Orbiting Satellites
Hall E (New Orleans Convention Center )
Janet L. Machol, NOAA, Boulder, CO; and J. C. Green, J. V. Rodriguez, T. G. Onsager, W. F. Denig, and P. N. Purcell

As part of the algorithm development effort for the Defense Weather Satellite System (DWSS), the National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center (NGDC) is developing operational algorithms for space weather sensors on the next generation of low-altitude polar-orbiting weather satellites. This presentation reviews the two new algorithms on which NGDC has focused: Energetic Ions (EI) and Auroral Energy Deposition (AED). Both algorithms take advantage of the improved performance of the Space Environment Monitor Next (SEM-N) sensors over earlier SEM instruments flown on NOAA Polar Orbiting Environmental Satellites (POES). This presentation also describes methods that we are evaluating for creating higher level products that would specify the global particle environment based on real time measurements.

The EI algorithm input is count rates from the four SEM-N high energy omnidirectional detectors. The EI algorithm iterates a piecewise power law fit in order to derive a differential energy flux spectrum for protons with energies from 10-250 MeV. The algorithm provides the data in energy flux units (MeV cm-2 s -1 sr-1 MeV-1) instead of just count rates as was done in the past, making the data generally more useful and easier to integrate into higher level products. Proxy data generated from POES data are used with the algorithm for validation, threshold optimization, and estimation of errors.

The AED algorithm estimates the energy flux deposited into the atmosphere [W/m2] by precipitating low- and medium-energy charged particles (0.03 eV to >1 MeV). The algorithm input is differential energy flux for electrons and protons over a range of energies and look directions. The AED calculations include particle pitch-angle distributions and assume that all particles in the loss cone precipitate. Energy fluxes are migrated to ionospheric altitudes using Liouville's theorem.

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