HR: 11:40h
AN: SA42A-06 INVITED     [Abstracts]
TI: Why Fly ITSP and GEC or Don't We Understand the Ionosphere and Thermosphere?
AU: * Paxton, L J
EM: larry.paxton@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723, United States
AB: The ionosphere/thermosphere (I/T) community faces some significant challenges in the next few years. Principal among these challenges is that of conveying to the broader space science community the need for additional, focused space-based research missions that address the major problems of I/T physics. What do we say when we hear that 1) the I/T is basically understood, 2) I/T science is about improving the specification of the I/T rather than answering basic questions and 3) the only reason we study the I/T is for its practical applications to communications, navigation and orbit-dynamics? The ability of first principles models to produce a reasonable fit to observations seems to provide prima facie evidence that we do understand the physics, chemistry and dynamics of the I/T. However, we have so few systematic, well calibrated, unambiguous, global measurements of the I/T and there are so many poorly characterized inputs to the models that there is a great range in the ability of the model to be "tuned" to reproduce a particular set of measurements. The ability of the models to reproduce the general behavior should enable us to determine what our "known unknowns" are and provide valuable insight into those processes or quantities that we must measure in order to make further progress in our understanding. Future missions, especially those like GEC or ITSP as well as potential Explorer-class missions, that look at the I/T in a new way, will tell us if there are "unknown unknowns" that await our investigation.. There are still new and exciting questions at all spatial and temporal scales in the ionosphere and thermosphere. The pending missions - Ionosphere Thermosphere Storm Probes (ITSP) and Geospace Electrodynamics Connections (GEC) - are vital to testing our understanding of the physics of the storm-time response of the I/T and the electrodynamic connection of the ionosphere with geospace, respectively. With these missions we seek to characterize the spatial and temporal variability of the I/T and to understand the root cause of that variability on a global scale and in a global context.. Coupled with the rich variety and history of distributed ground-based measurements, we can address these issues that are at the heart of our need to understand the physical processes that are parameterized as sub-gridscale phenomena on the first principles models.
DE: 0355 Thermosphere: composition and chemistry
DE: 2407 Auroral ionosphere (2704)
DE: 2437 Ionospheric dynamics
DE: 2441 Ionospheric storms (7949)
DE: 2443 Midlatitude ionosphere
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly