Boundary-Oriented Precipitation Model: Toward Developing Instantaneous Representation of Global Precipitation

Johns Hopkins University, Baltimore MD

Investigators

Abstract

This proposal seeks continuation of support, to characterize global electron precipitation patterns. Earlier results include basic research findings, such as suppression of intense discrete aurora in sunlight, and surprising results about solar cycle dependencies, as well as the development of a boundary-oriented precipitation model. The boundary-oriented model has several advantages, including that diffuse aurora is compared only to diffuse aurora, discrete to discrete, polar rain to polar rain, and so forth. A powerful advantage of the boundary-oriented model is that it allows extrapolation from observations at a few given local times to the rest of the oval on a much more reliable basis (e.g., intense discrete aurora at premidnight are not interpreted as implying much about diffuse aurora postmidnight). Thus the boundary-oriented model should prove more adaptable to estimating global precipitation patterns. Instead of organizing the precipitation data by solar wind inputs or magnetometer indices (KP or AE levels), the data is self-organized, in the sense that a particle boundary (b2i, corresponding to the stretching of the magnetotail) is used. Making the model a bivariant function, including the open flux in the polar cap extends this self-organization. These two variables, b2i (magnetotail stretching) and open flux collectively represent the instantaneous state of the magnetosphere better than does simply knowing the input (solar wind) or ground magnetometer values. Moreover, the self-organizing nature of the approach also lends itself well to using individual pairs of DMSP satellite oval crossing (giving four local time snapshots) to infer the global precipitation pattern.